CHEMICAL RESEARCH IN ISRAEL

ר

-.

__ 1

.,,~~ .. ' .... ' . ,.-.;.,- .-.

JO({j ~ -rA N [L. 8'i; C/j04cDנ

.. '-'C ~ "':F Q •• ' ~ I"Lנ'ד .r . rb . ~\~'יין .;:.ז'ז" "...

*

I : INIS-mf'--9072 \

בושראלהכומוהמחקי ,_

CHEMICAL RESEARCH IN ISRAEL

לכימיההישראליתהחברהשל 49-ההכנס

אביב-רמתאביב-תלאוניברסטית ,

תשמ"גיבתשריכיין-כ"גי 1882באוקטובר 10-11

Ii\ ,פי."..".'

CHEMICAL RESEARCH IN ISRAEL

I .'''.היי.ק.';.""""""""""" "F ~ __________________ ' -_-~ l' בישראלהכימיהמחקר

CHEMICAL RESEARCH IN ISRAEL

לכימיההישראליתהחברהשל 49-ההכנס

אביב-רמתאביב-תלאוניברסיטת ,

תשמ"גבתשרי-כ"דכ"ג 1982באוקטובר 10-11 , ,

* (~ ,~I

._J ~_ " ,"_ ."_'"t ~ d? '"' ! .... _ .. 1'11"י i?t , 1 .ד ~ ...

- I -

__ .. r t.'·'· .................... .............................. " ..... ק.' .... ~

- 1 -

כנםדתהער== =:== ==== ==== =====

גרלדברגישראליר"ר

.. פנצינריעקבאברהמישמחהחברים

צירקזסטפובר-אליקדמה

צישנרבסקיארריגרטטפלדשמשרו

קרסרבראדראררמנדלרררה

שצפילרשמערימררנרעילה

שרףדפנהנבריגיל

זלץטל(תערוכה:נרכר;דעטל

לכימיהלחרגהערכתםאתמביעיםלכימיההישראליתיהחנרההכנטרעדת

פערלהשיתרףעלתל-אביבבארניברסיטתמדרייקיםלמדעיםרלפקרלטההכנס.בארגרועזרהרהענקת

ראגרדכימיתלהנדטההישראליתהאגררהעםבשתרףהראהכנטאיגךי

תעשייתית.לכימיההאינגינרים

._-_ . .,..,.,....,- .... _י_._ 1w ... pr _._י· _____ 1 __--.

•

f

..

,

- II -

_________ ~ SM -ייייי-י._________ r I

-זז-

תמיכתםעלמטההרשרמיםרחבררתלמרסדרתגםנתרנההמארגניםתררת

זה:לכנסותררמרתיהם

בע"מלישראלריסקרנטבנק

בע"מלישראללארמיבנק

בע"מלישראלאיגורבנק

כע"מאלקטררניצירדאלדו

בע"מישראמקסחברת

בע"מקרמירה

ב~זמ(ישראל)לנרסיס

בע"מאסטרגל

בע"ממרטכניקה

בע"מחמררד

בע"מאלקטריקפריד

בע"ממדעיצירדאנקור

בע"מרמדעירפראימיכשררררנר

בע"ממתקדמרתטכנרלרגירת-אפא

בע"מלישראלמדעימכשרר ,.איאס. .אי

בע"מאינסטרימנטססייאנטיפיק"מדע"

בע"מ(ישראל)דאטהקרגטררל

בע"מ ) 1972 (שיררקאל-חמה

מכיררתקידרםשיררק,פירסרם,-שילרב

בע"מ ) 1977 (רשרתיקרכומ.

בע"מכימיקליםגציגריותמרקררי

בע"ממדעימכשררלרמיטריו

בע"מתהליכיצירדלחמו

בע"ממדעילצירדחברהש.א.ק.

l'

,

-______ 1

..,

- I l l -

notnpaa

d i ' i i o ' T i t o Ton >A>ann nrpnan aunn pi ."\bt\b on>s

r\-\}pb i rro ci'bp niNpaoi ni>iy j

tPDioon d^jurnn .oianpn

pm I K nie/Aia rmiea n innx

an

4 'on no'osn nyv» !?in a'NSOi oj^n 'K^ nioib d>nniyn

5

oiaapn bw 'n'^an no©a nunb

d>annu»nn .

bob no^ja O>DID nuynaa n!?N ;iniN

fi nib ^ nin*> mapn!? d>BTTJ nirpcpn OKI

intn inw1* nx'm ^D^B ''na naie/n u mapn . lbnb oi iaai

I

_~J ך

. n.

- 111 -

===================יללכידעמ

מדרייקים;למדעיםבפקרלטהראירנשטייךשנקרבבנינימתקיימיםהכנסאריעי

בר-שירה.בארדיטררירםנעררהחגיגיהפתיחהמרשברקלהלך.פיררטראה

השרניםבמזנרניםלקנרתניתךקליםרמשקארתערגרתכריכים.קלרת.אררחרת

שנקר-פיסיקהבבניךנמצאיםהכנסלמקרםהסמרכיםהמזנרניםהקמפרס.בשטח

התפרצרת.ביתרבמרזיארךמשפטיםבניךגילמו.בניךלב).(מזנרך

הסטרדנט.בכיתהמרכזיתבמנזהררקאןמרגשרתבשרירתאריחרת

אחה"צ. 4שעהעדפתרחיםרהמנזההמזנרניםרבהלימרדיםפגרתבתקרפת

ירתר.מארחררתבשערתגםפתרחגילמךמזניך

4מסיהכניםהשערימילנמצאיםהכנסבאילרשרתהערמדיםלרכבחניהמגרשי

ניתךלא •לצערנרלהנדסה.הפקרלטהרבניךהתקניםמכרךלידלקמפרס, 5-ר

ה~מפיס.שלהפנימיבשטחלחנרתאישרר

רחרמרתגירתכתיבה,דפיהכנס,תכניתהתקצירים,חרברתעםאישייםתיקים

גביעלשמםאתלרשרםמתבקשיםהמשתתפיםההרשמה.שרלחךלידמחרלקיםאחר

הכנס.אררעילכלכניסהכרטיסמשמשרתאלהארתן;רלעברדהתגירת

שנקבעהזמניםלרחעליתרהלהקפדהנדרשיםהישיברתראשרירשביהמרצים

המרקצבהזמךיישמרמרצהשלכלכדיחשרבהזרהקפדהלהלן.רמפררטמראש

בישיברתהניתנרתהרצארתשמיעתלתכנךלמשתתפיםלאפשררכדילהרצאתר,מקבילרת.

f

1<

I

- IV -

I

------)

ך

~ ____________________ """"""",,"".כ.?".I • . ....."'-'-,_,, .. " , .:

- IV -

===========================הכנסאריעישלכלליתתכנית

1982באיקטיבר 10אי~יימ

09:45 - 08:30

11:30 - 09:45

ברכית:

(שנקר).הפיסטרימתציגתהכנתשירה),(ברהרשמה

שירה)(ברחגיגיפתיחהמישב

הברר.ד"ר

י.דינשטייךפריפ'

לביאא.פריפ'

לכימיההישראליתהחברהנשלא

תל-אביבאיניברסיטתרקסיר

יהמסחרהתעשיהמשרדשלראשלמדעך

כימיתלהנדסההישראליתהאגידהנשיא

תעשייתיתלכימיההאינגינריםאיגידנשיא

אברהמיש.ד"ר

שלדיבי.מר

-תשמ"ב)ישראלפרס(חתךיירטנריהישעפריפ'מרכזית:מליאההרצאת

הבסיסי"במחקרימגמית"כייינים

14:00 - 11:30

17:00 - 14:00

18:00 - 16:00

.'

~

18:00 - 17:00

19:00 - 18:00

,יאירנשטייך)(שנקרהשינימהכימיהבתחימיפיסטרימתציגתצהריים.הפסקתמתקדם,אנליטימיכשירעלמימחיםהרצאית

הכימיה.יבהיראתהשינלםהכימיהבתחימיהרצאיתישיבית

בישראל"הכימיהבהיראתיבעיית!וצרכימהנישאעלרב-שיח

לב)(אילם

סמיאלד.פריפיהדייך:מנחה

עבידיתעלתיכיךלתלמידיפרסיםייענקיזהמישבבמסגרת

בכימיה.מצטייניתגמר

(המשך).פיסטריםתציגת

הפקילטהדיקאךגלעדי,א.פריפימטעםפירמליתלאפניםקבלת

לכימיההחיגיי"רבך-ראיבך,א.יפריפימדיייקיםלמדעים

קל).(כיביד

~ _--. .•-...'oח ........ ~ ...... ~_,_ ..... _ ,.~,_, __>י ___- .,~ '-'

1;

- V - "-'' .. ,-.ר

- v -

1982באיקטיבר 11בו.יימ

09:30 - לב)(אילםמליאהמישב 08:30

יהפתיחהמדעשר-נאמיייבלפריפו :פתיחהדברי

-אייזנראיריד··רמרכזיתהרצאה .לישראלי·כימיקלימנחנריתיפתיח"מחקר

16:00 - פיסטרימשלרציפהתציגה 09:45

12:15 - השיניםהכימיהבתחימיהרצאיתישיבית 09:45

13:30 - צהרייםהפסקת 12:15

16:00 - השינימהכימיהנתחימיהרצאיתישיבית 13:30

18:00 - הנישאעלרב-שיח 16:00

הכימיתיהתעשיההמחקרשלהתפתחית·יכיייני

." 80-הנשניתבישראל

גלעדיא.פריפ'הדיין:מנחה

הכנס,נעילת

שנקר-פיסיקה.לבניןהכניסהבאילםהכנסימישניבמשךתתקייממדעיציידתציגת

אירנשטיין.בבנין 10.10.82-הא'בייםייערךתעסיקהמפגש

המוצגיחהעבידיתרשימתההרצאית,שלמפורטזמניםליחמיכאלהלן

לכנס.שהיגשיהתקציריםיאיסףהפיסטריםבתציגת

היאזינחיברתכליליםאשרהמסחריותהחבריתשלהפרסימיםתיכו

המפרסמים.שלהבלעדיתבאחריותם

___ f '-~--'''''''' -------~ - .... _-_ .. ~_.~

f

- vi -

14.00

14:45

15:05

15:25

.00

1

4

5

6

15:45

16:00 7

16:20 8

16:40

.5 O^IN ,14:00 - 17:00 'K 01

E. ZADOK and Y. MAZUR (Invited Lecture)Oxygen Atoms: Formation, Properties and Utilization in Organic Synthesis

S. HIRSH and D. BEN-ISHAIAmidoalkylations of Dienes with Adducts of Glyoxylic Acid.

S. BITTNER and Y. ASSAFSynthesis of Phospha(V)azenes by Redox Condensation Reactions.

S. BRAVERMAN and Y. DUARStereochemistry of the Electrophilic Fragmentation-Cyclization ofAllenic Sulfones and Sulfinates: Stereoselective Synthesis of Chiral<x,3-Unsaturated y-Sulfines.

Discussion (Coffee)

Y. ITTAHStereochemical and Electronic Factors in Hydrocarbon Carcinogenesis.

E.M. KOSOWERSingle Group Rotation. An Early Step in the Transduction of ChemicalStimuli: Neurotransmitters. A Structural and Mechanistic Model forIonic Channels in Biomembranes.

A. TABAK. N. LOTAN, S. SIDEMAN and U. TAITELMANComposite Sorbents - Applications in Biomedical Engineering.

ObiK ,09:45 - 12:10 O1>

09:45

10:30

10:50

11:10

11:30

11:50

2

10

11

12

13

14

Z. RAPPOPORT (Invited Lecture)Some Mechanistic Aspects of Nucleophilic Vinylic Substitution.

D. HUPPERT, H. KANETY and E.M. KOSOWERKinetics and Mechanism of Intramolecular Electron Transfer in Solution.

A. MINSKY and M. RABINOVITZ

Singlet-Triplet Equilibrium in Doubly Charged Benzenoid Polycyclic Systems.B. WEITMAN and E.A. HALEVIThe Mechanism of Thermal Decomposition of Diazofluorene in Solution.

S. HOZ and D. AURBACHNucleophilic "Vinylic-like" Substitution in Bicyclobutane System.

B.A. FEIT and U. MELAMEDConfigurational Stability of Vinyl Carbanions Derived fromMono-substituted Activated Ethylenes.

I f- VII -

.3!? D!HN ,13:30 - 15:45 'a DP

13:30 3 Z. GOLDSCHMIDT (Invited Lecture)Pentacoordinate Irontricarbonyl Complexes. Model Compounds forthe Study of Organometallic Pericyclic Reactions.

14:15 15 S. AVRAMOVICI-GRISARU and S. SARELNovel Macrocyclic Iron(II) Complexes.

14:35 16 G. SAGIV and L. NETZERSynthesis of Bifunctional Surfactants and Investigation of theirAbility to Form Multilayer Molecular Systems.

14:55 17 U. ZOLERQuaternary Imidazolium Salts: Electrophilic Substitutions andtheir Onium-anion as an Intermediate (?)

15:15 18 I . WILNER and Y. DEGANIPhotosensitized Electron Transfer Reactions in OrganizedEnvironments as Photosynthetic Models.

.111 1"DW311K ,09:45 - 12:15 '3 Dl '

09:45 60 R. REISFELD (Invited Lecture)Luminescent Solar Concentrators for Energy Conversion.

10:30 62 D. MEYERSTEIN (Invited Lecture)Chemical Reactions of Unstable Compounds with Metal-CarbonBonds in Aqueous Solutions.

11:15 63 Y. SOREK. H. COHEN and D. MEYERSTEINReactions of Iron(II) Protoporphyrin with Free Radicals.A Pulse Radiolytic Study.

11:35 64 M. COJOCARU andJ.M.E. GOLDSCHMIDTA Study of the Mechanism of Formation of Polymeric Species in theMass Spectra of Pentacarbonyltrimethylsilyl-iso-cyano- Complexesof Group VI Metals.

11:55 65 H. COHEN, E.S. GOULD, D. MEYERSTEIN, M. NUTKOVICH and C.E. RADLOWSKIIntermolecular Vs. Intramolecular-Electron Transfer Reactions inCobalt(III) Pentaamine Coordinated to Pyridinyl Radicals.

1- VIII -

i"i* ,in-p .b 'ana -

111 p»oer:niN ,13:30 - 15:55 !3 01

(v'Z. DORI (Invited Lecture)Macrocyclic Complexes of Iron and Cobalt

F. FROLOW, A. EFRATY and A. EISENSTADTA Novel [Ru4CC0) (y-CO)2(n

2,n5,n2-indenyl)(n5-dihydroindenyl)] Cluster.

A. EISENSTADT and A. EFRATYPreparation of Some Unusual u-Carbene Complexes of Ruthenium.U. OLSHER. E.R. BLOUT, G. SHOHAM and W.N. LIPSCOMBComplexes of Lithium Salts with the Macrocyclic PolyetherDibenzo-14-crown-4.

15:15 69 F.H. HERBSTEIN and W. SCHWOTZERExtended Donor-Acceptor Molecular Compounds Between Thionesand Chains of Bis (iodine) Molecules.

A. GIVAN, I . MAYER and L. BEN-DORUranium in Apati tes .

•,•"./. 13:30

14:15

14:35

14:55

61

66

67

68

.205 • p ' u e m i N ,13:30 - 15:55 '3 01*

13:30 74 J . BLUM (Invited Lecture)Catalyt ic Hydrogenation and Transfer Hydrogenation Reactions inMulti-phase Systems.

14:15 75 M. ROTEM and Y. SHVOFormation and Reactivity of Ruthenium Carboxylate Complexes.

14:35 76 I . PRI-BAR and J.K. STILLEFormation of New C-C and C-0 Bonds in Homogeneous CatalyzedOrganotin Coupling Reaction.

14:55 77 E. KEINAN. P.A. GLEIZE and N. GREENSPOONPalladium Catalyzed Reductions with Group IVa Hydrides.

15:15 78 Y. BLUM. Y. SHVO and M. KAMCatalyt ic Oxidative Coupling of Alcohols with Ru,(C0)12 .

15:35 79 A. EFRATI. I . FEINSTEIN-JAFFE and M. SEGALThe Application of Palladium(O)-Diisocyanide Matrices in theHeterogeneous Catalytic Hydrogenation of Alkenes and Alkynes.

- IX -

103 ,13:30 - 16:00 'N 01'

13:30 81

14:10 82

14:50

15:00 86

15:20 87

15:40 88

A. LIFSHITZ (Invited Lecture)Anatomy of Complex Reaction Systems. Kinetics of CombustionReactions from Ignition Delay Times.

A. PERSKY, M. BROIDA and R. RUBIN (Invited Lecture)Quasiclassical Trajectory Studies of the Dynamics ofThermoneutral Atom-Molecule Reactions.

Discussion

E. POLLAK and R.E. WYATTA Semiclassical Adiabatic Theory of Resonances in 3DReactive Scattering.

C. LIFSHITZ and P . BERGERKinetic Energy Release Distributions (KERDs) for Gas Phase Ions;C4Hg0

+.

M.G. KATZ and T. WYDEVEN, Jr.Grafted Microporous Reverse Osmosis (RO) Membranes.

"n -.103 p'oenilN ,09:45 - 12:15 0 1 '

09:45

10:25

—11:05

11:15

11:35

83

84.

89

9091

11:55 92

S. WEISS (Invited Lecture)Picosecond Kinetics by Infrared Line Broadening

0. KAFRI (Invited Lecture) ]Some Applications of a New Moire Technique in Chemistry.

Discussion

M. KAGAN, A. LEVI and D. AVNIRFormation of Spatial Dissipative Structures in a Photochemical System.

K BAR-ELI and W. GEISELER

The Minimal Chemical Oscillator and Perturbations of BistableChemical System.

N. LOTANOrder and Disorder in Nonaqueous Solutions of Electrolytes.

- X -

.a.103 "p^DBIiTiN ,13:30 - 15:45 '3 0 1 '

13:30 85 S. SPEISER (Invi ted Lecture)Novel Aspects of Electronic Energy Transfer in Solut ion .

14:15 93 P. PFEIFER, D. FARIN and D. AVNIRFracta l Surfaces: Chemistry in an Environment of a Non-integerDimension Greater than Two.

14:45 94 ri. BIRNHOLTZ. Ch. AHARONI, A. NIR and N. LOTANNon-equilibrium Chemisorption in Heterogeneous Systems.

15:05 95 A. GEDANKENMagnetic Circular Dichroism Studies of DABCO.

15:25 96 N. LOTANMolecular Dynamics of Polymers in Chaotropic Media.

.205 "p'OemiN ,09:45 - 12:20 '3 Dl

f 09:45 102"; D. CAHEN (Invited Lecture)V ____^^ Photoelectrochemical Solar Cells.

10:20 103 Ch. YARNITZKY (Invited Lecture)Double Layer Effects in Square Wave Polarography.

11:00 104 D. TALMOR and E. KIROWA-EISNERDelayed Open-Circuit Voltammetry.

11:20 105 J.Y. BECKER, D. DOLPHIN, J.B. PAINE III and S.F.B. PICKETTElectro-catalytic Reduction of O~ by Metallo-porphyrin Monomersand Dimers.

11:40 106 H. YAMIN and E. PELEDLow-rate Li/S Organic Cell.

12:00 107 JLJJABAI and J. BINETHThe Behaviour of the Li/SOCl2 System at Elevated Temperatures.

- XI -

.0

o!?lN ,14:00 - 15:55 'K Dl

nyc?

14:00 115 E.V. DEHMLOW (Invited Lecture)Phase Transfer Catalysis; Fundamentals and Recent Developments.

14:45 118 Ch. SHEINDORF, M. REBHUN and M. SHEINTUCHAdsorption from a Multicomponent Solution.

15:05 119 M. BERC2ELLER and H. ARTZIPreparation of a Dual Function Reforming Catalyst for the Productionof a-Naphtbol from Tetralon Based on Bond's Theory.

15:25 120 M. WEISS-YONOVITCH and Y. SASSONConverting of Alkyl Chlorides to Alkyl Bromides by PTC. Influence ofPTC on Equilibrium Position of Reversible Reactions.

15:40 121 L. MENDELOVICI and Y. SASSONGas Phase Halogen Exchange in Alkyl Halides Catalyzed by SupportedMolten Phosphonium Salts.

.a in -

.5 OtnK ,09:45 - 12:10 '3 Dl>

09:45 116 A. CANTONI (Invited Lecture)Problems of Scaling up to Jumbo Agitated Reactors, and ErgonomicInterrelation Between their Operators and their On-line Computer.

10:30 122 I. KOENIGSBERG and J. JAGUR-GRODZINSKIFlame Retarding Properties of the Block Copolymers of Bromostyreneand Styrene

10:50 123 L.M. SHORR. J. SEGALL and Z. BLUTSTEINThe Chemical Hygiene of Process Solvents. Systems ContainingTertiary Amines.

11:10 124 M. REBHUN. H. GRYNBERG, Ch. SHEINDORF and R. OFERTreatment of Industrial Waste from Oil Refineries

11:30 125 M. SHORR and E. WEINTRAUBInfluence of Chloride in Phosphoric Acid on the Corrosion and Electrochemical Behaviour of Irou and Nickel Alloys.

11:50 Discussion.

1- XII -

. 0

.5

•in - 'A 3'

,13

win ,r:30 -

pn16 :00 '3 D l '

Y. ZIMMELS (Invited Lecture)Applications of Magnetic Liquids.

14:20 126 K.S. SPIEGLER, T.S. BRUN and A. BERGWater and Salt Transport Through an Ion-exchange Membrane.

14:40 127 R. NEUMAN and Y. SASSONSimultaneous Reaction and Dis t i l l a t ion in a Packed Column.

15:00 128 E. WELLNER, N. GARTI and S. SARIGCrystal Structure Modification of Saturated Fats by Food Emulsifiers.

15:20 129 Z. KRAUS. M. FRENKEL and N. GARTIEmulsifiers as Weighting Agents.

15:40 130 H. ISAACS. N. GARTI and M. FRENKELDispersing Agents in Aqueous and Organic Systems.

.111 V>oenTiN ,14:30 - 17:30

14:30 136

15:10 137

15:5016:10

16:30

16:50

17:10

139

140

141

142

S. BERMAN (Invited Lecture)The Analysis of Seawater for Trace Metals - A Challenge toAnalytical Chemists.

M. ARIEL (Invited Lecture)

Anodic Stripping Analysis Applied to Environmental Surveillance.

Discussion (Coffee)

A. LORBER and Z. GOLDBARTElimination of Drift from Analytical Signals in MultielementAnalysis by the Generalized Internal Standard Method.R. BAR and Y. SASSONDetermination of Carbonate/Bicarbonate Ratio by C NMR.

E. SHOENBERGER and J. KASSOWITZMicro Dry Ashing for Trace Selenium Determination in Organic Matrices,

I.B. BRENNER. I. GAL, H. ELDAD, L. HALICZ and D. HOFFERApplication of the Inductively Coupled Plasma for the QuantitativeAnalysis of Geological and Related Materials,

1- XIII -

.111 I ^ D B J I I K ,11:30 - 13:30 «K Ql">

"Developments in Analytical Methods and Instrumentation"nye> v s p n

11:30 144 D. ORD and J . FREMAJERDistributed Local Area Networks for Chromatography Laboratories.

12:00 145 P. VAN HOUTRecent Development in High Resolution Chromatography: UltraPerformance Fused Si l ica Capillary Columns and Liquid On-columnSampling.

12:20 146 D. FUSTERDiode Array Technology Applications in UV/VIS Spectrophotometryand LC/UV Detection.

nr nunn imom rnaon imne/flN niNnn by romn

"n -.104 IN 222 np»tj*>3-1pJ» ,13:30 - 16:00 lH DT>

13:30 147 J . DUDLEY HERRON (Invited Lecture)"Turning Water into Wine": Student Difficulties in Solving Problems,

14:20 148 TIKQ .K

14:40 149naiynn !?ta pnan

15:00 150 taia .n

15:20 151 bam .KI >3v-p ."! . n i x .? "yau"n pbn x»n n'n>Dn o

15:40 152bw

- XIV -

.a 'ai ls : i" i> . V»OW31IKI ipjw »3'33 HN leipnn iimona JOIVJ ;uixnn

.on .onmay vspii yjo >iain

1 19 M. SAHAI. H.E. GOTTLIEB, A.B. RAY, A. ALI, E. GLOTTER and I. KIRSONSteroidal Lactones Related to the Withanolides from PhysalisPeruviana L.

2 20 D. BARKAN. S. CARMELY, A. GROWEISS, D. CZARKIE, Y. KASHMAN and U. SHMUELIMarine Diterpenes with a Cembrane Skeleton: Structure and Chemistry.

3 21 Y. KASHMAN and A. GROWEISSLatrunculin, a Marine Macrolide from the Sponge Latrunculia Magnifica.

4 22 R. SEGAL, I. FEUERSTEIN and A. DANINIdentification of Several Chemotypes of Artemisia herba alba Assofrom the Middle East.

5 23 I. TAMIR, A. ABRAMOVICI, R. SEGAL and I. MILO-GOLDZWEIGThe Red Blood Cell as a Model for Studying the Mechanism ofCitral Teratogenicity.

6 24 E. BREUER. J. DEUTSCH and P. LAZAROVICIA Convenient Synthesis of the Aggregation Pheromone of TriboliumCastaneum and T. Confusuro.

7 25 V. VANDE VELDE, D. LAVIE. R. ZELNIK, A.K. MATIDA and S. PANIZZACordialin A and B, Two New Triterpenes from Cordia verbenaceaeDC (Boraginaceae).

8 26 Y. SEGALL and J.E. CASIDASome Properties of the Phosphorothiolate 5 -oxide Intermediate.

9 27 I . I . ZIDERMAN and J . BELAYCHEAlkali-catalysed Depolymerisation of Cellulose in the Presenceof Anthraquinone.

10 28 E. MENACHEMOFF, 0. AWERBUCH and R. HABERNovel Derivatives of 6-Ethoxy-l,2-Dihydro-2,2,4-Trimethylquinoline(Ethoxyquin) and Their Biological Ac t iv i t i e s .

11 29 A. GAATHON. B. FRIDLENDER and N. ISRAELIThe Fluorescence of Thyroxi-Fluorescein Conjugate and i t s Applicationin a Diagnostic Immunoassay for Thyroxine.

12 30 J. VAN MIL. L. ADDADI, M. LAHAV and S. SIFNIADESA Model for the Generation and Amplification of Optical Activity.

13 31 I. WEISSBUCH. E. GATI, L. ADDADI, Z. BERKOVITCH-YELLIN, M. LAHAVand L. LEISEROWITZInduced Resolution of o-Amino Acids by Crystals of a-Glycine Growingat the Interface.

- XV -

14 32 A. BALAN. Y. SEGALL and A. TISHBEERacemic and Pseudoasyraraetric (±) Dialkyl MethylphosphonatesIsolation and NMR Studies.

15 33 Y.H. KIM, A. BALAN. A. TISHBEE and E. GIL-AVChiral Differentiation by P-(+)-Hexahelicene-7,7'-Dicarboxylic AcidDisodium Salt. Resolution of DNP-a-Amino Acid Esters by HighPerformance Liquid Chromatography.

16 34 S. WEINSTEINHPLC Resolution of Enantiomers Using Chiral Additives in theMobile Phase. Extension of the Method to Compounds other thanthe Protein Amino Acids.

17 35 P.A. RAMAIAH and E. GIL-AVIsolat ion and Assignment of Configuration of the Diastereomerictrans-Chloro(N,N-Dimethyl-D-phenylglycine)(3-ethylcyclopentene)Pt(I I ) Complexes.

18 36 A. RAMAIAH, E. GIL-AV and A. GEDANKENCorrelation between Circular Dichroism and the Absolute Configurationin the 3-Alkylcyclopentene System.

19

20

21

37

38

39

22

23

24

25

26

40

41

42

43

44

Z. GOLDSCHMIDT, B. CRAMMER and R. IKANThermal Acid-Catalysed Rearrangements of Trans Methyl Chrysanthemate.

S. SAREL, N. WONGVISETSIRIKUL and S. COHENThe Formation and Crystal Structure of a [2+5] Cycloadduct.

J. DEUTSCH and M. CHRIKIStereochemical Effects on Mass Spectral Hydrogen Rearrangements inBicyclic Diones under Electron Impact.

E.M. KOSOWER, N.S. KOSOWER and A. RADKOWSKYFluorescent Thiol Labeling and Other Reactions with Bromobimanes;Glutatitione Sulfide (GSG).

A.L. WEISTautomerism in Dihydro-1,3,5-Triazine Systems.J . ZIZUASHVILI and B. FUCHSPhotochemical Behaviour of Biased Homo-conjugated Ketones:2-Methylspiro[5.5]undeca-l,3-dien-7-one.

Z. GRAUER. D. AVNIR, S. YARIV and L. HELLER-KALLAISurface Effects on Conformation and Spectra of DibenzotroponeAdsorbed on Various Montmorillonites.

S. BRAVERMAN and J .C. MARTINOrtho Lithiat ions of Arenesulfinic Acids. New Method for Elect rophi l icAromatic Subst i tut ion.

1- XVI -

27 45 S. BRAVERMAN, D. REISMAN, M. FREUND, D. RABINOVICH and F. FROLOWSkeletal Rearrangement of a 2,6-Dithiaadamantane-2,2,6,6-TetraoxideDerivative during Thermal and Photochemical Sulfur Dioxide Extrusion.

28 46 A.L. WEIS and Z. PORATDynamic NMR Investigation of the Tautomerism in Dihydropyrimidines

29 47 Z. GOREN, P. DAN and I . WILLNERComplexation of Organic Compounds to Cyclodextrins - A r t i f i c i a lModels for Substrate-Receptor Interact ions in Enzymes.

30 48 Y. DEGANI and I . WILLNERControl of Photoinduced Electron Transfer Reactions in Posi t ivelyCharged CTAB Micelles, DODB Vesicles and ZrO2 Colloids.

31 49 J.Y. BECKER and B. ZINGERAnodic Oxidation of Allenic Hydrocarbons in CH^CN.

32 50 M. HALPERN. Y. SASSON and M. RABINOVITZEvidence of Hydroxide Ion Extraction in the Phase TransferCatalyzed Isomerization of Allybenzene.

33 51 S. SHATZMILLER, E. BAHAR and R. LIDORGeometrically Controlled Dimerization of Acetone-0-methyl Oxime,Uses for Pyrrole Synthesis.

34 52 A. KALIR, J.M. KAMENKA and P. GENESTEPreparation of Substi tuted Piperidinocyclohexanecarbonitri les.A New Variant of the Strecker Reaction.

35 53 S. BRAVERMAN, D. REISMAN and M. FREUNDNovel Synthesis of Vinylallenes and 1,3-DimethylenecyclobutanesThrough Base-Catalyzed Dimerization and Cyclodimerization ofAllenic Sulfones.

36 54 S. BRAVERMAN and M. FREUNDThe Synthesis of New 3,4-Dimethylenethiolane Derivatives:Potent ia l Tetramethyleneethane Precursors.

37 55 A.L. WEIS and M. BERNSTEINThe Reaction of Benzylidenacetylacetone with Benzamidine.

38 56 A.L. WEIS, F. FROLOW, M. BERNSTEIN and J . FAHIMASynthesis and Crystal Structure of 2,4-Diaza-6,7-Benzo-8-0xabicyclo[3.3.1]-Nonanes.

39 57 S. ANTEBI and Z. GOLDSCHMIDTThe Reaction of Carbenes with Cycloheptatriene-Fe(CO)_ Complex.

40 58 E. KEINAN and Z. ROTHA New Indicator Substrate for Classif icat ion of Nucleophiles.

41 59 E. KEINAN, M. SAHAI and I . KIRSONReductive Elimination of Vicinal Oxygen Function with Palladium(o).Applications in Withanolides Interconversions.

- XVII -

42 80 E. KEJCNAN and M. PERETZPalladium Catalysed Allylic Alkylation with Allenyl Stannane

43 143 N. GARTI, E. WELLNER. A. ASERIN and S. SARIGAnalysis of Sorbitan Fatty Acids Esters by HPLC.

44 131 J. SEGALL. L.M. SHORR and S. WEINERSynthesis of Dialkylphosphoric Acids from POC1,, P9O5 an(* Alcohols.

45 132 Y. SASSON, N. GARTI and A. ASERINPreparation of Monoglycerides of Fatty Acids from Epichlorohydrinby Phase Transfer Catalysis - Part I.

46 133 R. SHWARTZ. M. FRENKEL and N. GARTIMultiple Emulsions: A Novel Technique to Overcome the UnpleasantTaste of Drugs.

47 134 E. PROSS and Y. SASSONExtraction of Alkoxide Ions by Liquid Anion Exchangers.

48 135 M. BERCZELLERDetermination of the Crys ta l l in i ty of Aluminium Oxy-hydroxideUsing Thermal Analysis.

49 71 N. YELLINLow Temperature Synthesis of Chalcogenides.

50 72 E. FUCHS, H. COHEN, K. WIEGHARDT and D. MEYERSTEINOn the Difference in the Oxydation of 1,4,7 Triacetate-1,4,7Trazacyclonane Nickel(II), in Aqueous Solutions, by HydroxylRadicals and Electrochemically.

51 73 H. COHEN, G. GINZBURG, N. JUBRAN and D. MEYERSTEINEffect of Methylation on the Properties of 1,4,8,11 Tetraazacyclo-tetradecane Nickel(I) in Aqueous Solutions.

52 108 H. RELLER, E. KIROWA-EISNER and E. GILEADIEnsemble of Microelectrodes: Digital Simulation by the Two-DimensionalExpanding Grid Method Applied to Cyclic Voltammetry.

53 109 Z. HARZION, N. CROITORU, D. HUPPERT and S. GOTTESFELDTime Resolved Photocurrent Photopotential and PhotoluminescenceStudy of n Type CdS and CdSe Photoelectrodes.

54 110 J. RISHPON, I. RESHEF and S. GOTTESFELDEllipsometric and Impedance Measurements of Oxide Film Grown onRuthenium Electrodes.

55 111 D. ISSAHARY and D. KI3YERSTEINCooperative Phenomena in the Electrochemical Behaviour of AnodesModified by Anodic Deposition of Nickel Complexes.

56 112 G. GINZBURG (the late), B. ZINGER and J.Y. BECKERA Semi-Empirical Method for Resolving Overlapping Waves in CyclicVoltammetry.

57 113 M. ELAM, E. PELED and E. GILEADICyclic Voltammetry of Pb and Sn in Solutions of Aluminum Bromideand KBr in Aromatic Hydrocarbons.

- XVIII -

58 114 R. TULMAN. A. GOLAN, A. MEITAV and E. PELEDCalcium - Thionyl Chloride High-Rate Cell.

59 97 Z. KOTLER and A. NITZANLocal Field Enhancement in Aggregated Dielectric Films.

60 98 C. LIFSHITZ, M. GOLDENBERG and Y. MALINOVICHTime Resolved Photoionization Mass Spectrometry.

61 99 N. MANOR. R. REISFELD and D. AVNIRFluorescence Studies of Ruthenium Tris-Bipyridine and ofEuropium Tris-Benzoylacetonate Adsorbed on Porous Supports.

62 100 E. NISSANI, B. HAYMAN and R. KORENThe Kinetics of Binding of Bilirubin to Bovine Serum Albumin.

63 101 D. ROJANSKY and D. HUPPERTPicosecond Time Resolved Electronic Energy Transfer in MixedCrystals and Fluid Solutions.

64 101a D.A. WEITZ, S. GAROFF, J.I. GERSTEIN and A. NITZANResonance Raman Scattering and Fluorescence of MoleculesAdsorbed on Silver-Is?and Films.

o^Tinya o'Nain ojab lettirw nmayn ba bv

by

liny baa nji 'byn n»3n'n

1DD13 riA^n - P .fiNjnna ne/Aio rniay - 0 ,mnnn riKsin - L

manrn n»n>aORGANIC CHEMISTRY

- 1 -

OXYGEN ATOMS: FORMATION, PROPERTIES AND UTILISATION IN ORGANIC SYNTHESIS

Elazar Zadok and Yehuda Mazur

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot 76100, Israel

We have found that oxygen atoms formed by microwave discharge of 02 and CO2

can be used for oxidation of organic compounds in preparative scale.

The lecture will deal with the reactions of O-.atoms produced in this way with

saturated and unsaturated organic compounds. The main products of the oxidation

of the saturated compounds were tertiary alcohols formed with high retention of

configuration, while the oxidation products of olefins were epoxides and carbonyl

compounds. Aromatic compounds led mainly to hydroxylation at ortho and ipso

positions. A mechanism is postulated for this reactions,involving the intermediacy

of triplet diradicals, in the case of unsaturated compounds, and triplet radical

pairs in the case of saturated compounds.

- 2 -

SOME MECHANISTIC ASPECTS OF NUCLEOPHILIC VINYLIC SUBSTITUTION

Zvi Rappoport

Department of Organic Chemistry

The Hebrew University, Jerusalem 91904, Israel

Many mechanistic routes are available for the substitution of a nucleofuge X at-

tached to a vinylic carbon by a nucleophile Nu (eq. 1) « These involve addition-elimi-

R3R2C =C tX)RJ + Nu~-* R3R2C=C(Ru)R1 (1)p a

nation and elimination-addition routes, and reactions via carbocations, carbanions and

1 2radicals. The two most important routes, i.e., nucleophilic addition-elimination '

3and vinylic SM1 differ in many mechanistic respects. The nucleophilic addition-eli-

mination is activated by electron-withdrawing a-substituents, the nucleofugality of X

follows the order F>>Cl^Br and the stereochemistry is mostly retention of configu-

ration for good nucleofuges and stereoconversion for poor nucleofuges. The SN1 route

is facilitated by electron-donating a-substituents, the nucleofugality order is Br>Cl

and the stereochemistry is stereoconversion or partial inversion. These routes will be

discussed in relation to two mechanistic questions: (a) Whether the addition-elimina-

tion process is multi-step proceeding via an intermediate carbanion or is a single

step route and (b) The role of ion pairs in the S I route.

1. Z. Rappoport, Adv. Phys. Org. Chem., 7_, 1 (1969).

2. Z. Rappoport, Ace. Chem. Res., 14, 7 (.1981).

3. P.J. Stang, Z. Rappoport, M. Hanack and L.R. Subramanian, "Vinyl Cations", Aca-

demic Press, 1979.

1- 3 -

PENTACCORDINATE IRDNTRICARBONYL COMPLEXES.

MODEL COMPOUNDS FOR THE STUDY OF ORGANOMETALLIC PEPICYCLIC REACTIONS

Zeev Goldschmidt

Department of Chemistry, B a r - I l a n U n i v e r s i t y , Ramat-Gan

Despite current interest in symmetry-controlled organic reactions study of

peri cyclic reactions of transition metal organometallic compounds has so far

been rather limited. The recent extensive application by Hoffman of molecular

orbital theory to determine the electronic structure and bonding in organometallic

complexes provided a convenient framework for our search of pericyclic reactions

of these compounds.

A qualitative analysis of symmetry-allowed reactions of square pyramid (_1)

and trigonal bipyramid (2) pentaccordinate irontricarbonyl complexes will be pre-

sented. I t will include the presentation of correlation diagrams and frontier

orbital interactions for cycioaddition of cyclic heptatriene complexes, diene-diene

isomerizations and [1,3] sigmatropic shifts of c,n-allyl complexes. Symmetry-

allowed metal-hydrogen, metal-carbon and metal-metal dyotropic shifts involving

square pyramids to trigonal bipyramid interconversions will also be discussed.

V

- 4 -

Amidoalkylations of Dienes with Adducts

of Glyoxylic Acid.

S. Hirsh and D. Ben-Ishai

Department of Chemistry, Technion-Israel

Institute of Technology, Haifa.

Amidoalkylation of butadiene with glyoxylic acid-methyl-carbamate adduct 1_>

at room temp, and in the presence of an acid catalyst, afforded the neutral

vinylbutyrolactone derivative 2_ {12%~) and the acid pipecolic acid derivative

3 (9%).

H

HO-CH-CC" HI 2

NHCO2Me

1

R2NH

NHCO2Me HO CO2Me

HX V

NHCO2Me

CO2Me

NHCO2Me

i 5_ X=Br,SMe 16

Isoprene, 1,3-cyclohexadiene, 2,5-dimethyl-2,4-hexadiene, 2,4-dimethyl-l,3-

pentadiene and other dienes were found to react similarly and gave lactones as

the major reaction products.

Reacting the vinyllactone 2_ with amines as nucleophiles afforded the amides 4.

Soft nucleophiles like HBr and MeSH reacted with the vinyllactone 2 in an

SN2 type reaction and afforded the unsaturated derivatives 5. The bromo acid

(5, X=Br) was further converted to the methoxy ester 6 on refluxing with

methanol.

The mechanism of the formation of the lactones from the adduct 1 and

dienes will be discussed.

- 5 - 0

SYNTHESIS OF PHOSPHA(V)AZENES BY REDOX CONDENSATION REACTIONS

Shmuel Bittner and Yonit Assaf

Department of Chemistry, Ben-Gurion University of the Negev

Beer Sheva, 84120, ISRAEL

Triphenylphosphine reacts with primary amides in the presence of diethyl azodicar-

boxylate to produce N-substituted phospha(V)azenes along with diethyl hydrazinedi-

carboxylate. Aryl carboxamides, haloacetamides, and acrylamide produce the corres-0II

ponding phospha(V)azenes (R-C-N=PPh_), aromatic and aliphatic primary sulfonamides

gives rise to N-sulfonylphospha(V)azenes (R-SO_-N=PPh,), and diphenylphosphinamide0 ^ •* 0

II II(Ph-P-NH-) gives the phospha(V)azene containing two phosphorus atoms (Ph2P-N=PPh2).

The reaction of bis-amides with triphenylphosphine produces bis-phospha(V)azenes as

does the reaction of bis-phosphines with mono-amides. Heterocyclic systems, con-

taining two phospha(V)azene linkages, have been prepared from bis -amides and bis-

phosphines in the presence of diethyl azodicarboxylate. A novel variation of the

reaction of a phosphine, an amide and an azo ester is the reaction of azodicarbon-

amide with phosphines. This reaction, using a variety of phosphines, has been

shown to produce a new class of phospha(V)azenes with a semicarbazidoacyl group on

the nitrogen atom (R3P=N-C0-NH-NH-C0-NH2). Structure proof for these compounds

and mechanisms for these reactions will be discussed.

- 6 -

STEREOCHEMISTRY OF THE ELECTROPHILIC FRAGMENTATION-CYCLIZATION OF ALLENIC SULFONES

AND SULFINATES: STEREOSELECTIVE SYNTHESIS OF CHIRAL a,g-UNSATURATED y-SULTINES.

Samuel Braverman and Yizhak Duar

Department of Chemistry, Bar-Ilan University, Ramat-Gan

Following our ini t ia l reports on the spontaneous fragmentation-cyclization

of allenic sulfones and sulfinates to ysult ines, the stereochemistry of the

reaction was examined. Addition of Br9 or CH,SC1 to (+) and (-)-a-methylpropargyl

Y-methylallenesulfinates, as well as to (-J-y-methylallenyl and (-J-y-Jt-butyl-

allenyl t-tutyl sulfones, generated optically active 6-bromo-(or 8-methylthio)-

y-alky1-a,$-dehydro-y-sultines.

i lII

K R

R = CH, , t - B u R = CH, t - B u

X = B r , CH3S

0I;

CH,

CH,

The chirality of the allene was transferred to the allylic carbon of the

sultine as can be seen by oxidation of the sultines to sultones. The relative

structure of each diastereomeric sultine was determined by i ts NMR data. The

weight of evidence argues against the intermediacy of a vinyl sulfene and suggests

the intervention of an ionic mechanism wherein the sulfonyl oxygen attacks the

bridged carbonium ion. Assuming an ionic reaction mechanism and determination of

the absolute configuration of the allenyl sulfones, allows one to further deter-

mine the absolute configuration of each sultinic diastereomer.

1. S. Braverman and D. Reisman, J. Amer, Chem. Soc. , 99_, 605 (1977); TetrahedronLetters 1753 (1977).

1- 7 - 0

STEREOCHEMICAL AND ELECTRONIC FACTORS IN HYDROCARBON CARCINOGENESIS

Yitzhak Ittah

Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot.

D.R. Thakker, H. Yagi, M. Croisy-Delcey and D.M, Jerina

Laboratory of Bioorganic Chemistry, National Institutes of Health, Bethesda, Md. 20205

Two diastereomeric diol epoxides can be obtained on a benzo-ring of Polycyclic

Aromatic Hydrocarbons from vicinal trans-dihydrodiols (1). The oxirane oxygen and

the benzylic hydroxyl group can have either ds (diol epoxide-1, DE-1,2) or trans

(diol epoxide-2, DE-2,3) relative stereochemistry. DE's with quasi-diequatorial hy-

droxyls exhibit higher tumoregenicity than those with quasi-diaxial conformation C1D.

The steric hindrance at the bay-region of B[c]Ph causes its DE-1 and DE-2 (newly

synthesized) to prefer the quasi-diequatorial conformation. This was unequivocally

assigned by the large values of Ju u = 8-9 Hz. Both DE-1 and DE-2 have similarH3-Hu

high tumoregenic activity C2D.

HO*

l.NBA

l^^ 2. Amberlite OH

Fluorination of BCcHPh at any of the positions 1,2,3, or 4 hardly affects the

carcinogenicity relative to the parent hydrocarbon. However, the K-region 6-fluoro-

derivative was 5-fold more active than BCcDPh [3D.

1. H. Yagi, D.R. Thakker, R.E. Lehr and D.M. Jerina, J . Org. Chem., 44, 3439 (1979).2. W. Levin, A.M. Mood, R.L. Chang, Y. I t tah , M. Croisy-Delcey, H. Yagi, D.M.

Jerina and A.H. Conney, Cancer Res., 40, 3910 (1980).3. Y. I t tah and D.M. Jerina, J . Fluorine Chem., 16, 137 (1980).

j

- 8 -

Single Group Rotation. An Early Step in the Transduction ofChemical Stimuli: Neurotransmitters. A Structural and Mechanistic

Model for Ionic Channels in Biomembranes

Edward M.Kosower

Department of Chemistry, Tel-Aviv University, Ramat-Aviv,Tel-Aviv, Israel and Department of Chemistry, State University of

New York, Stony Brook, New York, USA 11794

The rotation of a single group ["SGR"] is postulated as anearly step in the transduction of certain molecular signals.Specific illustrations are given for several neurotransmitters.Simple formula drawings show the local motion within the stimulusmolecule-receptor combination. Molecular models for ion "gating"with acetylcholine, glutamate and q-aminobutyrate are presented.The model for the acetylcholine receptor (AChR) is compatiblewith d-tubocurarine inhibition of AChR, electron micrographicevidence for a 20A central "hole" in the AChR and desensitizationof AChR by two molecules of acetylcholine.

Models for the ion channel of the acetylcholine receptor(AChR) and the sodium channel in biomembranes are proposed,utilizing a-helical polypeptides with "channel-active" (CAl aminoa c i d s in the s e q u e n c e : g l u ( l ) , l y s ( 5 ) , g 1 u ( 8 ) ,lys (12) ...accompanied by a counterpart set: lys, glu, lys> glu...The channels conduct ions via similar mechanisms, in which thekey steps depend upon single group rotation (SGR) of CA sidechains.

The difference between t h i o l - r e a c t i v e agonists andantagonists for disulfide-reduced AChR may be explained using themodel. Diversion of the opening/closing mechanism of the Na4*channel can account for the action of channel-opening toxins (twoc la s ses : (A) grayanotoxin I, batrachotoxin, aconi t ine ,veratridine (B) scorpion and sea anemone toxins). Channel closingtoxins act by blocking (tetrodotoxin, saxitoxiix, with brevetoxinP proposed as channel-filling. Gating (charge motion within themembrane) and threshold voltage opening are natural properties ofthe model: the ionic select ivi ty of the channel may have a s ter icand kinetic basis.

The similari ty in molecular weight for AChR and the Na +

channel is utilized to suggest a composition for the latter. Thepossibi l i ty that other ion channels (K , Ca , Cl~) function inthe same way is noted.

1- 9 - 0

COMPOSITE SORBENTS - APPLICATIONS IN BIOMEDICAL ENGINEERING

A. Tabak, N. Lotan, S. Sideman and U. TaitelmanDepartments of Chemical and Biomedical Engineering, and theSchool of Medicine, Technion, Haifa, Israel.

Hemoperfusion is a clinical operation by which undesired materials areremoved .rom the blood of intoxicated persons, using an extracorporeal device.The key element of such a device is the toxin-removing unit, usually a columnpacked with adsorbed particles. The demands set for such a unit are: high speci-ficity, high capacity and appropriate blood flow-through characteristics. Thepresent report describes the development of hemoperfusion columns made up ofcomposite sorbent particles for the removal of Paraquat ( an herbicide), usingFullers' Earth.

The highly specific adsorbent considered is a finely divided powder mater-ial, of large surface area. This powder is not biocompatible. Furthermore, theflow characteristics through a powder bed are not appropriate. Hence, we haveincorporated the powdered adsorbent into a gel-type material (agarose), andobtained composite sorbent beads exhibiting desired properties.

A detailed investigation on the equilibrium and the dynamic performancesof the Fuller's Earth -containing beads was carried out. Langmuir-type equili-brium isotherms were obtained. The maximal adsorption capacity of the beads wasfound to be 51.2 mg Paraquat/gr Fullers' Earth, which is identical to the valueobtained with the uncoated material.

The mass transfer characteristics of the composite agarose beads were14established, by measuring the adsorption and the escape rates of C-labelled

Paraquat. The values obtained for the diffusion of Paraquat (D= 1.4-2.8x10cm /sec) have been related to the composite characteristics of the sorbent, aswell as to the structure of the rolysaccharide and of the water contained.

The application of another hemoperfusion column made of composite beads,containing Zirconia for the removal of excess inorganic phosphate ions from theblood, will also be discussed.

- 10 -

Kinetics and Mechanism ofIntramolecular Electron Transfer in Solution

Dan Huppert, Hannah Kanety and Edward M. Kosower ,Department of Chemistry, Tel-Aviv University, Ramat-Aviv

Tel-Aviv, Israel 69978 ( also Departmentof Chemistry, State University of New York,

Stony Brook, New York ]1794 USA)

The picosecond pulse generated S, n D state of 6-N-4-methyl-phenylamino-2-naphthalenesulfonic acid'NrN-dimethylamide (TNSDMA)decays by intramolecular electron transfer (IET) somewhat fasterthan the appearance of the product, an equilibrium mixture of the

solvent cluster motion (1/t-i, lowest dielectric relaxation rate)over a wide range of temperatures with log k linear in 2/31ogl/n. Up to ca -15°C, "slow" IET processes probably vary in thesame way, but at higher temperatures are controlled by localgroup motion (l/t2/ second lowest dielectric relaxation rate) .A molecular model for the S^ t state-methanol complex ispresented.

1- 11 - 0

SINGLET-TRIPLET EQUILIBRIUM IN DOUBLY CHARGED

BENZENOID POLYCYCLIC SYSTEMS

Abraham Minsky and Mordecai Rabinovitz

Department of Organic Chemistry, The Hebrew University ofJerusalem, Jerusalem 91904, Israel.

Fused benzenoid systems such as anthracene, phenanthrene, chrysene and

3,4-benzophenanthrene were reduced with lithium, sodium and potassium in various

solvents to the corresponding antiaromatic doubly charged species. The NMR

and ESR patterns of the dianionsrevealed a strong dependence on the counter-

cation, solvent and temperature. This dependence is interpreted by the existence

of an equilibrium process between the singlet ground state and a thermally

accessible excited triplet state of the antiaromatic dianions. The direction

and extent of the equilibrium is determined by the energy gaps between the LUMO

and HOMO of these charged species which depends, in turn, on the topology of the

hydrocarbon and on the solvation properties of the obtained salt. When the

equilibrium tends toward the triplet state, NMR line broadening process is2

observed - up to a total disappearance of the signals and, in frozen, rigid

solutions, a Am =2 ESR signal is revealed.

1. Bates, R.B. in "Comprehensive Carbanion Chemistry", Elsevier: N.Y. 1980,Part; A, pp. 1-54.

2. Gunther, M. "NMR Spectroscopy", John Wiley, N.Y. 1980; pp. 325-331.

3. Wertz, J.E. and Bolton, J.R. "ESR Elementary Theory and Practical Applications",McGraw-Hill: N.Y. 1972; pp. 232-246.

- 12 - 0

THE MECHANISM OF THERMAL DECOMPOSITION OFDIAZOFLUORENE IN SOLUTION.

by Berta Weitman and E. Amitaf HalevfDepartment of Chemistry, Technion-IsraelInstitute of Technology, Haifa.

The thermal decomposition of diazofluorene (DF) in benzene at 70°C is foundto differ from that of diphenyldiazomethane »^ in two important aspects:

(a) The reaction is cleanly first order when oxygen is completely excluded.Even traces of 0£ retard the reaction,which departs from first order kinetics.These are restablished, with a greatly reduced rate, at high concentrations ofdissolved O2.

(b) Neither fluorenone nor fluorenoneazine is produced in any of the aboveconditions,bifluorenylidine (BF) being the only product observed.

The Arrhenius parameters for the uninhibited reaction (Eg=2'».7±0.6 kcal/mole;log10A=12.0±0.A) and the limiting behavior of the 02"inh?bited rates at high andlow O2 concentrations are consistent with the following mechanism, which is alsosupported by semi-empirical (MNDO) computations:

k

3F + DF

Its principal features are: (i) reversible tntersystem crossing between singletand triplet DF; (ii) quenching of the latter by a still uncharacterized oxygen-ated product (FO2); (iii) independent formation of triplet fluorenylidene (3F)from both DF and 3QF; and (iiii) the absence of any role for the singlet carbene(IF).

The implications of our findings for the interpretation of recent studies ofthe photochemical decomposition of DF are discussed.

References

1. D. Bethell, D. Whittaker and J.D. Callister, J_. Chem. S o c , 2466 (1965).

2. (a) T. Oncescu, M. Continanu and G. Balaceanu, Rev. Roumaine Chim. 17, 213(1972); (b) M. Continanu, T. Oncescu and R.N. Schindler, ibidTUT, 559 (1973).

3. J.T. Zupancic and G.B. Schuster, J_. Amer. Chem. Soc. (a) 102, 5958 (I98O);(b) 103, 9*6 (1981).

- 13 -

NUCLEOPHILIC "VINYLIC-LIKE" SUBSTITUTION IN BICYCLOBUTANE SYSTEM.

S. Hoz and D. Aurbach, Dept. of Chemistry, Bar-Ilan University, Ramat-Gan, I s rae l .

The mechanisms and the kinet ics of the reactions of various nucleophiles

with 3-halobicyclobutanecarbonitrile (1) were investigated. The reactions of

alkoxides with 1^ produces the 3,3-dialkoxycyclobutanecarbonitrile ketals (2). The

mechanism of the i r formation involves haloethers which are formed in the f i r s t

stage. These then produce the appropriate oxocarbonium ions in the next s tep .

The oxccarbonium ions are capable of trapping t-BuOH (which i s otherwise unre-

ac t ive) . In a solution of CF-CH^O" in t-BuOH, among the other products of th is

reaction are mixed keta ls whose stereochemical composition i s k ine t ica l ly con-

t ro l led . This composition differs markedly from that found in the thermodynami-

cally equi l ibrated system. Substi tution of Br for Cl in 1^ a l t e r s the ra t io

between the mixed keta ls and the difluoroethoxy ketal but does not affect the

stereochemical compositon of the mixed ke t a l . The d i f ferent ia l behaviour of the

element effect on product d is t r ibut ion together with the general stereochemical

course of the reaction are consistent with the final step of the reaction being

protonation of the carbanion that resul ts from the nucleophilic attack on 1_.

When a nucleophile as CN~ is employed, the reaction takes a different course.

3-cyano-3-chlorocyclobutanecarbonitrile (3 ) , 1,3-dicyanobicydobutane (4) and

3,3-dicycanocyclobutanecarbonitrile (5) were isolated from the reaction mixture.

-CN

- 14 -

CONFIGURATION!. STABILITY OF VINYL CARBANIONS DERIVED

FROM MONO-SUBSTITUTED ACTIVATED ETHYLENES

B.A. Fei t and U. Melamed

I n s t i t u t e o f Chemistry, Tel-Aviv Univers i ty , 69978 Ramat-Aviv, Is rae l

R.R. Schmidt and H. Speer

Faculty of Chemistry, Konstanz Univers i ty , Konstanz, West Germany

2 1

Substituents a t one carbon o f 1.2-disubst i tuted act ivated ethylenes Y-CH=CH-Z

(Z,Y: CN.Ph; COgR.Ph; CN,OR; CN,NR2; COgR.NRg; COgR.SR; COgR.OR)1, a f f ec t

the conf igurat ional s t a b i l i t y o f the derived v inyl carbanion (V.C.) on the o ther

carbon atom:

H " "* H (-H+)

^ c = c ^ c = cH ^ x Z H ^ ^ E

A general approach was developed fo r studying the dependence of the conf igura-*"• H

tional stabil i ty of V.C. derived from ^C = CCZ on the substituent Z, without anyinfluence of a C2-substituent. The pure cis isomers H'C=C:-H a n d u ^ C s C ^ H

were synthesized and were each reacted with Ph2C=O in presence of a base in varioussolvents at low temperatures:

^ ^Z D^ ^C(OH)Ph2

„ - vc(0H)Ph2 H' ^Z,c=c

l . z -

" + P»>2C«0

CN

CO 2CH 3

1.

2.Bo*eCHCI3-H2O

H —' H ~

The vinyl carbanion o'C = c-CN was con-|ri"gurationally stable, while n^^C-co cu

isomerized completely. Experiments were carried out to test the involvement of addi-

tion-elimination type reactions in formation of the isomerized reaction products.

1 . B.A. F e i t , U. Melamed, R.R. Schmidt and H. Speer, J .C.S. , Perkin Trans. I ,1329(1981); Tetrahedron 37, 2143(1981) and references c i ted there in .

- 15 - 0

NOVEL MACROCYCLIC IRON(II) COMPLEXES

Schely Avramovici-Grisaru and Shalom Sarel

The Hebrew University of Jerusalem

1 oWe have shown earlier ' that pyridoxal isonicotinoyl hydrazones

tend to chelate iron(II) both in vivo and in vitro to form red-brown crystals

m.p. > 400°) of FeUO-bis-pyridoxal isonicotinoyl hydrazones (1_-2J in

which the phenolic group, the double-bonded nitrogen and the oxygen atom of

the carbonyl group participate in metal binding. They are noted for their

enhanced affinity for ferrous ions, with rather moderate association constants

(log K 8.67 to 5.74).

We assumed that the binding constants of the ligands could be enhanced

if they were more rigid, namely, if the two units of pyridoxal isonicotinoyl

hydrazone in (JJ and (2) could be linked by a chain of five or more atoms

to form a macrocyclic system. Towards this end we designed the use of

iron (I I)-complexes Q.-2.) as templates for the production of the hitherto unknown

macrocyclic complexes of structures (_3) and (4.) where X_ equals CHp-CHp, 0 and NH.

The formation and properties of (3) and (4), and their possible conversion

(.3), R=H; Y=C1, Br, I (4),R=C0CH3; Y=Cl,Br, I.

into artificial enzymes3 by inclusion other metals such as copper, will be

discussed.

1. C. Hershko, S. Avramovici-Grisaru, G. Link, L. Gelfand, S. Sarel,J.Ldb.Clin.Med., 98, 99 11981). •

2 S Avramovici-Grisaru, S. Sarel, G. Link and C. Hershko, J.Med.Chem., .... U98Z)3* A E. Martel in "Metal Ions in Biological Systems", Ed. H. Sigel, Marcel Dekker

Inc., 1973, Volume 2, p. 207.

1- 16 - 0

D'U3up3iiD myyim ni'juDP r>mnVipVin jnoiyn 70 rnpinn

maim ,yioV TQY'I ii3n ,i*3 ?PIV ,a»AP apy

07'9 np'm *"y ni'iVipVin in niaais n x ' u n*3nyj<nn v n (L-B) Blodgett-i Langmuirn m y n n"33,V nu'P imps on mtv D'emna '33V . T I N D'B ViaAa nw niV'ys mVipVin Vw

ni'nwBN HT Aipn nianynV .D'jmn a'nuwn Vy ni'iVipVin in ma3i» mayn "'y ni'na3i!> nni7ipnniy m'na3i!» am manynn .n'Ai7i33ua ini yina in ,D'3iB' D'Qinna ni3Tun mty>v

niman nna O"7'auoKnn D'3an im'na n'33nm n'li'Dn inu»3c ru'nan ni7aAin L-BDP npxinn man pa7 maaiyn p a i majpn ima mVipVinn Ta D'7yi9n

17 11 A1WJ

U3i7pg"iip 7ei m'E>7 nn'aD '"y K'n ni'i7ip7in 7n niaDw n'TaV i n i ' ni!"fnnimin) ni'aiaiK'ViN nm7ip7in in niaow ni7apnn ia ' T Vy .npyin ma Vy

nu'X' mVya ni'iVipVin-in niaaw VapV in'3 .(nn'Don nVn nainn n'jATiNniaa3 Hi no iy .(irn'D nn»3D) np^inn HTDH VK maawn VE» ri'O'D m't»p "'y maAin

n m n njiefKin naawn nnVwn Dy D"nDn nn'apn TVnnw '3an nn'ap '"y ni'naai? an.H3P13 ii'TVipVin in naaw Vw HTWP niysim yin '373 n u i s n

wvnnvn on nn'spn nu'ya nvnaDw ai ni'TVipVin manyn nuaV in'3B' UNXDHT3 U3UP3T1D .nn iAlD ni'lDniN'Al JlTll'D 11131311 'Vya D"731'Yp313-n D'O3Up3TlPan'i7i3K nxiapi D'Jiiy D'pyin D'nuB»n7 irn^D HTPR npaxiin nVia "VKV Vya ni'nV T I Y

ina . tpj ' iy D'K3uai m'nn n'rnna n'n'3 naiAiia n'nVia nxiapV n3'3ii7 n3iP3B> n'73'mo.mnpn n'lVipVio in na3i» UTY'V n'ipp na'nan n'xnnV n i s n x nixiapn

nan Vy .V"3n niwi iV n'3npy D'3iy CH2=CH-(CH2)n-SiCl3*VV3 naan 'Vya13N mniBP ni'iiaay ai 7ii3iym nmVipVin in niasw mx'V onVi3' nN pnaV

niaawn ni3'K .nsip m x a ni'3n'nn3 nmviB' 'Vyanyxann ni'naaw ain manynn n"3a . m i ' i n x i?3i?p3iipniy VDD msnwn ni'iVipVin innnnVipVm inn naawn iina n'n'D naiAn n'mapyai .nn'DP ;D'aVi9 '3W VB» iTxanoVN »"y

n n m y n nsiwjoV ni3aV n'n in'3 HKT av&i .n'nVis n iapV nnViaxn nxiapnVB» yAn ni'iT ni ' in "'y nK»y3 IVNH niaiynn I T Q ' N .D'pxin u->nov>n Vy nimap

.(ATR) n'B'33n mmnn nw»e»a DUN NiB3'Na n'Bippnopsp "'yi D'JIK* n'Vn3

Vm 'DIP axnV y'Ann '3U313P l'Vnna niVapnn niniapn ni'naay amn naDw pan n'U3Vnpn miviyi qpna , in ia 'x ' m n»i?ann nai , 'n3 ' i imn

niniapn maiynV aiwn i n n ' IT n3'nan . i n n x i i n TVnn '13 i in o*iymnnn 'na3B>. L-B nu'wa mVapnnn IVNV

nni'na minun n'ymn n3'nan in n3'3yn 1x3'9 Vy mpaV Q'3n'3n n"3U3iap 0'3'Vnn niyxnna n"ou3'P D"iVipVin-Vy o»3an

ai '»in'B» VN*X3Uia IT n»m nu'wa niVapnnn ni'iVipVinn nisiynV .vtnn,D'VV3in D'3nupVN O'VAynV D'a'3ina nV3i ni'UP3'P ni3iann n*»3an Vnn

- 17 - 0

1 7 1 * 7T1K.n'uon 'tin'77 innn

(2 )

5 DIQ'PB

(3 )

p(i) 'n7n 7W nmpin n'XjionD-m *"y 7yi37 ixxinp ,2 mnja

ni'7'3nop7Kn nnunn iVnoa n i m y i ni'sxn 7713) u n u j i 70 m'JTDan niNxinnpi

monyni a"j»a ' B U D uyuo (5-1 A) i7ti D'AI7N3NI»

R

?

njnnun nummn . mannnmnnn rnaiAJi7

.KXIDH nmn

.2 mnya

:nni?n

1. a . Z. Yoshida, Top. Curr. Chem., 4£, 47(1973).b . D. Lloyd, H. McNab, D.R. Marsha l l , J . Chem. S o c , Perk in , Trans . I , 1260

(1975) .2. a. R. Weiss , C .Pr i e sne r , H. Wolf, Angew. Chem. I n t e r . E d . , 1 8 , 472 (1979).

b . D. Lloyd, R. K. Mackie, G. Richardson, and D.R. Marsha l l , Angew. Chem.I n t e r . E d . , 2 0 , 190 (1981).

3. U. Zoller, E.M.Burgess, R. Burger (Submitted for publication).

- 18 - 0

PHOTOSENSITIZED ELECTRON TRANSFER REACTIONS IN ORGANIZED ENVIRONMENTS ASPHOTOSYNTHETIC MODELS

Itamar Wi l iner and Yinon Degani

Department of Organic Chemistry, The Hebrew Unive r s i ty of Je rusa lem,Jerusalem 91904, I s r a e l

Photosensitized electron transfer reactions (eq. 1) are currently of interestas a means of solar energy conversion and storage.*)2 A basic limitation of suchreactions is the thermodynamically favoured recombination process of the photo-products. We have developed a series of charged interfaces i . e . SiO2 and Z1O2colloids, micelles and surfactant vesicles as a means to retard the recombinationreactions and consequently stabilize the photoproducts. 3>If In these interfacialsystems electrostatic repulsive and attractive interactions of the charged photo-products with the charged interface control the recombination process.

(eq. 1) A + D * J ^ * A" + D+

KbTo examplify t h i s p r inc ip l e the photosensi t ized reduction of propylviologen-

su l fona te , PVS° (.1), using Ru(bipy) |+ or a pos i t i ve ly charged Zn-porphyrine ass e n s i t i z e r s and t r ie thanolamine, TEOA, as e lec t ron donor i s 10-15 fold enhancedin the negat ively charged SiO2 co l lo id as compared to the s imi la r reac t ion in ahomogeneous aqueous phase. This enhancement i s a t t r i b u t e d to the repulsion of thereduced photoproduct PVST, from the charged in te r face to which the oxidized spec ies ,Ru(bipy)§+ , i s bound. Consequently, the photoproducts are s t a b i l i z e d againstrecombination and high quantum yie lds are obtained.

& (I) R = -CH2CH2CH2-SO3"

(2) R = -CH,

Another approach involves the inclusion of one photoproduct in to a receptors i t e . Cyclodextrins have been used as macromolecular recep tors . The photo-sens i t i zed decomposition of HI (eq. 2) using Pd-porphyrin as s e n s i t i z e r has beenaccomplished. In t h i s system methylviologen, MV^+, (2) i s a primary e lec t ronacceptor , and the reduced product , MVt mediates the formation of H2 in the presenceof supported Pt c a t a l y s t s . The oxidized product I2 i s entrapped in the CD-cavityand allows the accumulation of H2 (the f u e l ) . This system i s a so l a r convertingfuel c e l l . The po ten t i a l u t i l i z a t i o n of charged in te r faces and macromolecularreceptors for s o l a r energy conversion w i l l be discussed.

(eq. 2) 2HI h v » C D » H2 + I2-CD

1. M. Calvin, Ace. Chem. Res., 10_, 369 (1978).2. I. Willner et a l . in "InorganTc Reactions in Organized Media" ACS Sym. Ser. No.177

(1981).3. I . Willner, J.W. Otvos and M. Calvin, J . Amer. Chem. Soc . , 103, 3203 (1981);

Proc. Nat l , Acad. Sc i . USA., 78, 5928 (1981); J . Phys. Chem., 85, 3277 (1981).4. I.Willner and Y. Degani, J . cEein. Soc. Chem. Commun., in press~Tl982).

- 19 -

STEROIDAL LACTONES RELATED TO THE WITHANOLIDES FROM PHYSALIS PERUVIANA I..

M- Sahaia, H. E. Gottlieb3, A. B. Rayb, A. Alib, E. G1otterc and I. Kirsonc.

Departments of Organic Chemistry and Isotopes, The Weizmann Institute of Science,

Department of Medicinal Chemistry, Banaras Hindu University,. Varanasi, India,

Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel.

Further investigation of the Varanas! variety of Physalis peruviana L. 1

(Solanaceae) led to the isolation of two new steroidal lactones (la) and (3)related to the withanolides.

Physaloiactone B 3-0-g-D-glucopyranoside (la), an amorphous powder [a] n +3.7°is the first glycoside in this series, isolated so far. Although glycosidation ofsterols is a common process in nature, all the withanolides in which &-eliminationdid not occur in order to give the common 2-en-1-one system, had the 3P-0H groupin the free form and the oxygen function at C-1 as 1a-0H, la-OAc or 1-one.

The withanolides and their relatives are the only group of natural steroidscomprising compounds with the side chain a-oriented. Perulactone (2) isolatedsome time ago had the normal 173-oriented side chain which was however oxidizedat C-28 (OH level),thus enabling the closure of a y-'actone. The recently isolatedperulactone B, m.p. 217°C, [a] D +56.5° has the same type of this rarely encounteredside chain, but 17a-oriented. In the oxidatcve processes of ring A, a further stepwas achieved, leading to the transformation of the 1a,36-diol present as the la-acetate in (2) into the 2-en-l-one system present in (3).

The co-occurrence of steroids with a and 6 oriented side chains in the sameplant suggests a common pathway in the first steps of the biosynthetic processesleading from a 2^-methylene-choiesterol type precursor to the various withanolidesand related compounds.

The structures assigned to compounds (la) and (3) are based on spectral analy-sis, mainly 1H and 13C NMR and, whenever necessary, on chemical transformations.

(la)

1,.

27

(3)

Recent Developments in Naturally Ocurring Ergostane Type Steroids", a reviewby I. Kirson and E. Glotter in J. Natural Products 44, 633, 1981 and ref. citedtherein.

- 20 -

MARINE DITERPENES WITH A CEMBRANE SKELETON:

STRUCTURE AND CHEMISTRY

Diana Barkan, Shmuel Carmely, Ami ram Groweiss,Dorotha Czarkie, Yoel Kashtnan and Uri Shmuel i

Department o f Chemistry, Tel Aviv Univers i ty , 69 978 Ramat Av iv , Israe l

We have invest igated the crysta l and molecular structures of several di terpenes,

iso la ted from Red-Sea cora ls , w i th pa r t i cu la r a t tent ion to the conformational

aspects of the fourteen-membered cembrane r ing which i s common to these molecules.

The crysta l lographic data and corresponding molecular diagrams w i l l be displayed.

Since several structures of re lated natural cembranolide di terpenes, found in

other parts o f the wor ld , have been reported, a comparative conformational study

has now become meaningful. In th i s context two graphical representations of the

molecular conformations w i l l be shown, in order to (i_) i l l u s t r a t e the re la t i ve

tors ional s t ra ins and ( i j j show s i m i l a r i t i e s and differences between the various

conformations, which can readi ly be re lated to the posit ions o f the funct ional

groupsthat apparently determine the b io log ica l a c t i v i t y of these in te res t ing

molecules.

The conformation of the cembrane r ing i s expected to inf luence the chemical

behaviour o f the above natural products. Indeed, in several cases to be i l l u s -

t r a t e d , i t i s possible to correlate the conf igurat ions and conformations, as

observed in the so l i d and in fer red fro»n NMR coupling constants, with the course

of chemical reactions that take place.

" —HHg

- 21 -

LATRUNCULIN, A MARINE MACROLIDE FROM THE SPONGE LATRUNCULIA MAGNIFICA

Y. Kashman and A. Groweiss

Department of Chemistry, Tel-Aviv University

Ramat Aviv, 69978 Tel Aviv, Israel

New f ish toxins were isolated from the Red Sea sponge Latrunculia magnifica. A

fu l l structure determination of these toxins by spectroscopic methods, including new

NMR techniques, was aided by an X-ray d i f f rac t ion analysis of a crystal l ine deriva-

tive of latrunculin-A. The Latrunculins exhibit a new class of 14 and 16 membered

macrolides, to which the 2-thiazolidinone moiety is attached. Some of the biological

act iv i t ies w i l l also be discussed.

1- 22 -

Identi f icat ion of Several Chemotypes of Artemisia herba alba AssoFrom the Middle East.

Ruth Segal, Ilan FeuersteinDept. of Natural Products, School

of Pharmacy. The HebrewUniversity of Jerusalem

P.O.B. 12065Avinoam Danin, Dept. of

Botany, The Hebrew University, Jerusalem

Artemisia herba alba (Compositae) known as the "desert wormwood"is characteristic of the steppes of the Middle East and North Africa, it is wide-ly used in folk medicine as an anthelmintic, for relief from coughing, againstintestinal disturbances, colds, measles etc. A systematic investigation of thesesquiterpene lactones isolated from plants collected from various localitiesshowed marked differences in the constitution of their sesquiterpene lactones asis depicted in the Table. Evidently there exist several chemotypes among theArtemisia herba alba species growing in this vicinity. The broad range oftherapeutic effects ascribed to the plant may probably be explained by theexistence of several chemotypes.

Composition of Sesquiterpene Lactones in Various A_. herba alba populations.Site of Growth Sesquiterpene Lactone Reference

herbolide A (1_) (0.003%) Segal et al.herbolide B (2) (0.02%) Phytochem.l6_, 1237herbolide C (3) (0.002%) (1977).

1. Sede Boqer

2. Mizpe Ramon

3. Elat

4. Sinai

5. Ras El Hikma(Egypt)

(1) (0.16%)()(

herbolide A () ( )herbolide B (2) (0.015%)herbolide C (3_) (0.0016%)deacetylherbolide A (4) (0.02%)herbolide D (5) (0.021)

l lB-H-tatr id in D (6)3-oxo-lle-H-tatridin D (7)l la-H-gal l ic in (8)

santonin (9)

Segal et a l .Phytochem.in press

Gordon et a l . J .Nat. Prod. 44, 432(1981). ~~

Khafagy et a l .Planta Medica 20,90 (1971). ~

OR

1- 23 -

THE RED BLOOD CELL AS A MODEL FOR STUDYING THE MECHANISM

OF CITRAL TERATOGENICITY.

I. Tamir and A. AbramoviciDevelopmental Pathology Lab

J. Casper, Pathology DepartmentTel-Aviv University, Tel-Aviv

and

R. Segal and I. Milo-GoldzweigThe Dept. of Natural Products

The School of PharmacyThe Hebrew University, Jerusalem

The teratological effect of citral (3,7-dimethyl-2,6-octa-

dienal) on chick embryo has repeatedly been reported. Since ci-

tral was found to be potent hemolysing agent it was decided to use

the red blood cell as a model for elucidating the mechanism of

citral toxicity. By using various inhibitors it was demonstrated

that citral hemo'ysis proceeds through oxygen radicals.

Compounds which give rise to free radicals are known to

induce teratological effects. It is suggested that this mechanism

may be responsible for citral teratogenicity.

1- 24 -

A CONVENIENT SYNTHESIS OF THE AGGREGATION PHEROMONE OF TRIBOLIUMCASTANEUM AND T. CONFUSUM

1 1 2Eli Breuer , Joseph Deutsch , and Philip Lazarovici

1 2Department of Pharmaceutical Chemistry, School of Pharmacy, and Department of

Zoology, The Hebrew University of Jerusalem

Suzuki has shown recently that the structure of the aggregation pheromone

e<1

of Tribolium mentioned in the title is 4,8-dimethyldecanal. This structure was

proven by synthesis.2

Our approach to the pheromone is based on the Julia terpene synthesis.

Reaction of ethylmagnesium bromide with cyclopropyl methyl ketone C D gave

2-cyclopropyl-2-butanol (2_). Treatment of 2_ with hydrobromic acid gave 4-methyl-

3-hexenyl bromide (3_) which was converted to Grignard reagent and reacted with J_

to give 2-cyclopropyl-6-methyl-5-octen-2-ol (4_). Tre atment of 4_ with hydrobromic

acid gave 4,8-dimethyl-3,7-decadienyl bromide (5), a compound having the carbon

skeleton of the desired peromone. The synthesis was completed by displacement of

the bromide by sodium acetate to give acetate 6^which was saponified to 4,8-dimethyl-

3,7-decadienol CZ)« The tw0 double bonds were saturated by hydrogenation over

palladium to give 4,8-dimethyldecanol (8_) which was oxidized by dimethyl sulfoxide-

oxalyl chloride to give the desired pheromone as a mixture of two racemates. All

reactions afforded products in high yields and in high purity.

The biological activity of the final product and of the intermediates,

and their specificities will be reported.

ACKNOWLEDGEMENT: We thank Elana Wiener for technical assistance in the syntheses.

1. T. Suzuki, Agrio.Biol.Chm., 44_, 2519 O980).

2. M. Jul ia , S. Jul ia , and R. Guegan, Bull.Soe.Chim.Frcm.Qey 1072 ( I960) .

- 25 -

Cordialin A and B, Two New Triterpenes from Cordia verbenaceae DC (Boraginaceae)

V. Vande Veldea, D. Laviea, R. Zelnikb, A.K. Matidab and S. Panizzab

The Weizmann Institute of Science, Rehovot, Israel

Instituto Butantan, Sao Paulo, Brasil

In a search for biological active compounds from brasilian flora, from the

leaves of Cordia verbenacea , two new dammarane-type triterpenes were isolated:

cordialin A (la) and B (II). Their respective structures were established by

comparing their PMR, CMR and MS. Compound la, C_QH ,0 • M+ 486, mp 112°C, UV

225 nm (e 13,540), IR 3400, 1670 and 1600 cm" , produced a monoacetate Ib, M+

528. By using trichloroacetyl isocyanate with PMR monitoring, two esterifiable

OH functions were detected, which based on various deductions were located at

C-3 and C-<11. The hemiketal bridge was disclosed by two pairs of doublets at

6 4.31 and 4.15 for the 19-protons, and in the CMR by a signal at 6 98.68 for

C-3. An llot-OH (eq) was established through a deshielding effect observed on

18-H, 6 3.1 (2.7 in Ib). The side chain is characterized by an a,B-unsaturated

carbonyl and a gem-dimethyl substituted epoxide. Compound II C .H.-Or, M 490,

mp 117°C, IR 3350 and 1625 cm , no UV max., was found to be closely related

to cordialin A. The spectra of II differed from la only for the side chain

signals (NMR and CMR). It had the 20-22 double bond 6 1.56 for the 20-Me

compared to 2.1 in la, and a glycol system replacing t\ epoxide. No carbonyl

was present. H

HO'.

II

- 26 -

SOME PROPERTIES OF THE PHOSPHOROTHIOLATE S-OXIDE INTERMEDIATE

Yoff i Segal!

Israel I ns t i t u te fo r Biological Research, P.O.Box 19, Ness-Ziona 70450, I s rae l .

John E. Casida

Pesticide Chemistry and Toxicology Laboratory, Universi ty of Ca l i f o rn i a ,

Berkeley, CA 94720, U.S.A.

The proposed phosphorothiolate S-oxides, 1 , obtained on m-chloroperoxy-~~ ""' (12)

benzoic acid (MCPBA) oxidation of S-alkyl phosphorothiolatesv * ' and probably

also on biooxidation activation is a very short l iv ing intermediate. Attempts

to direct ly observe 1 were so far unsuccessful. Althouth the f i r s t products

to be observed and isolated are phosphinyloxysulfonates, 29 Some properties

of 1 could be derived on MCPBA oxidation in various alcohols.

(R'0)2P(0)S(0)R2 .

31 ~

Thus, P nmr monitoring of the oxidation reaction indicates that complete

phosphorylation of the solvent occurs i f the reaction is carr ied out in

primary alcohols. These resul ts are independent of the J>-alkyl moiety and the

appropriate t r i a l k y l esters are the ul t imate products. Oxidation in sec-

alcohols gives an almost 1:1 mixture of esters resu l t ing froir phosphorylation

b y ^ and the appropriate d ia lky l phosphates from i n i t i a l rearrangement of J.

followed by alcoholys is. The l a t t e r der ivat ives are obtained almost exc lus i -

vely in t e r t i a r y alcohols. Pure d ia lky l phosphates are also exclusive products

on i n i t i a l oxidation in aprot ic solvents, followed by reaction wi th alcohols.

1. Y. Segall and J.E. Casida, ACS Symposium Series, 171, 337 (1981).

2. Y. Secall and J.E. Casida, Tetrahedron Letters, 23, 139 (1982).

- 27 -

ALKALI-CATALYSED OEPOLVlERISATION OF CELLULOSE

IN THE PRESENCE OF ANTHRAOl'INONE

Israel I. Ziderman and Janine BelaycheIsrael Piber Institute, P.O* Box 8001, Jerusalem 91080,

Anthraquinone (AO) promotes early deli^ni^ication and stabilisation ofcellulose during alkaline pulping of wood. Quantitative analyses ofpulps1 indicate that cellulose-dissolution is accelerated in thepresence of A0o

Alkali-catalysed depolymerisation of hydrocellulose was studied at97°C under nitrogen. In the presence of sodium anthraquinone-2-sulphonate(AMS), the rates of both the chain-propagated unzipping-reaction andthe competing termination-reaction were lowered. Since the formerreaction was inhibited to a greater extent than the latter, lessdissolution of cellulose occured in the presence of AMS at thistemperature. This result indicates that the mechanism hithertoadvanced^ for oxidative stabilisation of collulosic chain-ends bycoupling to the chemical reduction of AQ is probably incorrect,,

The inhibitory action of AMS at 97°C is ascribed to its possible effectin diminishing the degree of ionisation of reducing chain-ends.

As a possible mechanism for the accelerated dissolution of celluloseat pulping temperatures, it is proposed that AO promotes intra-chainscissions in cellulose, enhancing the dissolution of chain-fragmentswithout unzipping. This degradative effect of AQ may be mediated bythe formation of keto-cellulose and/or aldehydo-cellulose in a free-radical mechanism, involving the action of hydrogen peroxide that isformed in situ in the presence of AQO

References

1. N. Vanderhoek, personal communication; Bo Kosikov et_ al_o, Paperi jaPuu-Papper p_. Tra_ 62_ (1980) 229.

2, W.Ho Algar et_ al_., Appita 33 (1979) 33; K, Ruoho and F, Sjostrom,Tappi 61 (1978) 87, —

- 28 -

rtovel Derivatives of b-Ethoxy-1 ,2-Dihydro-2,2,fr-Trimethylquinol ine (Ethoxyquin)

and Their Biological Activities.

E. Menachemoff, 0. Awerbuch and R. Haber.

Abie Ltd., Pharmaceutical and Chemical Industries.

A; R

CH20H

CH

B; R = CONH,

Ethoxyquin is an antioxidant, widely and mainly used as a preservative

in livestock feed. Novel ethoxyquin derivatives (amides, N-glycosides,

carbamates and ureides) were prepared and their biological activities

investigated. Ethoxyquin and some of its new derivatives (like A and 8,)

act like vitamin E under biological conditions. A model demonstrating

such an activity and possible applications of the new compounds are

di scussed.

1- 29 -

THE FLUORESCENCE OF THYROXI-FLUORESCEIN CONJUGATE AND ITS APPLICATION INA DIAGNOSTIC IMMUNOASSAY FOR THYROXINE.

Ariel Gaathon, B. Fridlender and Nurit Israeli

Ames Yissura, Ltd.Jerusalem, P.O.Box 5577

Thyroxine, presumably due to its iodine content, has been shown to exertheavy fluorescence quenching upon flurophores chemically bound to it.Specific antibody binding to thyroxi-fluorescein (T4F) has been found topartially relieve this quenching (1). It is reported here that serum pro-teins, other than specific immuno-globulins, exhibit similar fluorescenceenhancement, which can be removed by 8 Anilino-naphthalene-1-sulfonicacid (ANS). The presence of small (0.1%) quantities of non-ionic deter-gents enhances T4F fluorescence depending on the pH. The enhancement ofTriton x 100 is shown to be up to 500% at pH > 12.

We describe a useful application of Triton x 100 enhancement in a simple,short and precise fluoroimmunoassay system for the diagnostic determinationof thyroxine in serum samples. The assay involves the use of 50 ul of serum,a release of thyroxine from serum proteins with thiomersal,sequential incu-bation with T4F and PEG facilitated double antibody percipitation. Thefluorescence in the percipitate is determined in 0.1 N NaOH containing 0.2%triton x 100. The assay's performance, in the range of 30 nM up to 240 nM,is characterized by <6% precision, both inter and intra assay, a sensitivityof 8 nM and long-term stability cf the reagents. It has attractive potentialfor wide practical use.

(1) Smith D.S., Enhancement fluoroimmunoassay of thyroxine, FEBS Lett.,77, 25, (1977).

- 30 -

A MODEL FOR THE GENERATION AND AMPLIFICATION OF OPTICAL ACTIVITY

Jan van Mil, Lia Addadi and Meir Lahav, Weizmann Institute of Science, Rehovot,Israel; S. Sifniades, Allied Chemical Corporation, Morristown, N.J., U.S.A.

During recent years we have been involved in research towards the generationand amplification of optical activity from achiral or chiral racemic molecules.See scheme.

crystallization

reaction

—P., chiral products

Using a family of diacrylates as a model system, we found that small quantitiesof chiral products, resulting from a topochemical photodimerization in the solidstate, when reintroduced in a fresh crystallization of the monomer, retard theformation of the crystal phase from which they were generated, resulting in anexcess of the second crystal phase. This phenomenon, which proved to be very gen-eral and very effective in the resolution of enantiomers, and which we have termed"The Reversal Rule", finds its origin in a stereoselective adsorption of the chiraladditive on to the growing faces of the crystal stereochemically similar to it,thereby retarding its growth while leaving the second enantiomer almost unaffected.*

However, due to the intrinsic properties of this adsorption mechanism, anamplification as we envisaged in the scheme cannot be achieved this way. We haverecently found a system which, based on the same principle of additive effects,resulting in diastereomer like molecules, does lead to amplification in the way ofthe scheme.2 The crystallization of the nickel complex DL-e-amino-a-caprolactam(DL-ACL)(which crystallizes in chiral crystals) in the presence of small amountsof L-lysine, leads to an excess of the L-complex, which after hydrolysis and ring-opening of the lactam gives L-lysine?

The mechanism of this process of direct amplification will be discussed interms of ligand exchange leading to two diastereomeric impurities (D,D,L' andL,L,L') which interact selectively with D,D,D and L,L,L crystals respectively, theD,D,Lf leading to the stronger interaction and thus to stronger retardation.

1. J. van Mil, L. Addadi, E. Gati and M. Lahav, J. Amer. Chem. Soc. 104, 3429(1982).

2. W.J. Boyle, Jr., S. Sifniades and J.F. van Pepper, J. Org. Chem. 4£, 4841(1979).

3. J. van Mil, Ph.D. Thesis, Weizmann Institute of Science, (1982).

1- 31 -

INDUCED RESOLUTION OF a-AMINO ACIDSBY CRYSTALS OF a-GLYCINE GROWING AT THE INTERFACE

I. Weissbuch, E. Gati, L. Addadi, Z. Berkovitch-Yellin, M. Lahav and L. LeiserowitzDepartment of Structural Chemistry, The Weizmann Institute of Science, Rehovot,Israel.

Experiments in which one could perform an induced resolution by crystals ofa-glycine growing at a solution/air interface will be discussed. These experi-ments are based on the changes in crystal habit induced stereoselectively on a-glycine crystals when grown from aqueous solutions in the presence of smallamounts of DL mixtures of amino acids. In these experiments we exploit theintrinsic packing and conformational features of the glycine crystals (spacegroup P2i/n); the glycine molecules form H-bonded layers in the ac plane viatranslation symmetry adopting a conformation such that one of its C-H bonds isparallel to the unique b axis.

A mechanism involving the selective adsorption and occlusion of the enantio-merically pure impurities on the enantiotopic (010) and (OlO) faces of the plate-like glycine crystals will be discussed.

The morphological changes and the proposed mechanism demand that in theaffected substrate crystals, the DL impurity must segregate along the b axis duringcrystal growth; occluded D impurity should prevail at the +b half of the crystal,whereas the L impurity should prevail at the -b half. These predictions wereexperimentally confirmed by HPLC experiments involving chiral separation of aminoacids (studies done in cooperation with Dr. S. Weinstein).2

The above experiments suggested that when such growing plate-like crystals areeither floating on the solution/air interface or resting on the glass bottom of thebeaker, the crystal will grow only along that b direction, corresponding to the (010)or (010) face, which is exposed to the aqueous solution. Furthermore, from theracemic mixture of a-amino acids, only the appropriate enantiomer will be select-ively adsorbed and occluded on this face. The opposite face which is in contact withair or glass will be hindered in growth. In such a manner, the glycine crystalsgrown in the presence of racemic mixtures of a-amino acids contain only one of theenantiomers.

1. I. Weissbuch, E. Gati, L. Addadi, Z. Berkovitch-Yellin, M. Lahav andL. Leiserowtiz, submitted for publication.

2. S. Weinstein, Angew Chem. Int. Ed. Z\_t 218 (1982).

1- 32 -

Racemic and Pseudoasymmetric (-) Dialkyl Methylphosphonates

Isolation and NMR Studies

A. Balan, Y. Segal 1 and A. Tishbee

Israel Inst i tute for Biological Research, P.O.B. 19, Ness-Ziona 70450, Israel.

The P nmr spectra of bis - (+) - 2-butyl (1) and bis (+) -3,3-dimethyl-2-butyl methylphosphonates (£) showed a 1:2:1 signal rat io attr ibuted

to four isomeric compounds: The d, 1 pair A and the two meso forms B, and C..

0G«. 0GR

C H , — P = 0 0 = P - CH-,3 k i 3

0G$ 0GR

(S,S) (R,R)A _ _

G = ^ j 2-butyl £ } 3,3 dimethyl-2-butyl

The two isometic meso compounds are each pseudoasymmetric due to thecombination of four different substituents at the phosphorous atom and the C~symmetry of the molecule. The same stereochemistry is well known for carboncompounds e.g. pentitols and pentaric acids.

In accordance to their p nmr spectra a 1:2:1 isomeric ratio was alsoobtained by HPLC on silica gel. The separated fractions of (£) gave each asingle peak in the 3 1P nmr (-30.1, -29.1, -27.5 ppm).

The product from methylphosphonousdichloride and two moles of optically31pure (+)-2-butanol had only one P nmr signal and one peak on HPLC confirming

the above assignment.

C H 3 -

(

?GRP = 0

6GS

r,R,S)B

0

QG

OG

(s,

R

S

R,c

CH3

s)

- 33 -

CHIRAL DIFFERENTIATION BY P-(+)-HEXAHELICENE-7a7'-DICARBOXYLIC ACID

DISODIUM SALT. RESOLUTION OF DNP-a-AMINO ACID ESTERS BY

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Y.H. Kim, A. Balan, A. Tishbee and E. Gil-Av

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot, Israel

It has been shown previously that silica gel, modified by electron withdrawing

substances such as R(-)-2-(2,4,5,7-tetranitrofluorenylidene-9-nminooxy) propionic

acid [R-(-)-TAPA] or riboflavin, permits effective resolution of optical isomers

capable of charge transfer (CT) complexation with the chiral reagent on the statio-

nary phase. We wish now to report on the extension of our studies to the use of

electron donating compounds as the chiral CT complexing component on the silica

gel.

P-(+)-hexahclicene-7,7'-dicarboxylic acid was chosen as the donor-modifier,

since helical polyaromatic molecules display relatively high stereoselectivity on CT

complexation.

The chiral support was prepared by coating silica gel with the disodium salt of

tne above diacid, which is insoluble in organic solvents such as CH-Cl- and n-hexane.

N-2-4-Dinitrophenyl (Dnp) derivatives of the isopropyl and/or methyl esters of Ala,

Val, Isoleu, Phe and Phegly were resolved with n-hexane, containing 1-2% of isopro-

panol, as the eluent. The resolution factors were generally higher than 1.1. The

enantiomers of the methyl ester of Dnp-Leu were, however, not separated under the

experimental conditions (room temperature, flow rate - 1 ml/min).

Some tentative correlations between structure and chiral differentiation of the

Dnp esters will be discussed.

By a judicious choice of derivatives, chiral reagents and mobile phase composi-

tion, it should be possible to develop the present approach into a general tool for

the enantiomeric analysis of Dnp amino acids. Furthermore, such electron donor sup-

ports should be of wide interest, for the resolution of many other classes of com-

pounds, as many substances can be made strong electron acceptors by derivatization

with reagents containing moieties such as di- or trinitrophenyl.

- 34 -

HPLC RESOLUTION OF ENANTIOMERS USING CHIRAL ADDITIVES IN THE MOBILE PHASE.

EXTENSION OF THE METHOD TO COMPOUNDS OTHER THAN THE PROTEIN AMINO ACIDS

By S. Weinstein

Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel

We have introduced recently new chiral additives to the mobile phase and1 2achieved efficient and sensitive HPLC resolutions ' of the enantiomers of all the

underivatized protein a-amino acids. These additives are copper complexes with

N,N-dialkyl-a-amino acids. For the enantiomeric analysis of a mixture of all the

common amino acids, the analysis has to be performed in two stages: First, the

mixture is separated into groups on a cation exchange resin, eluted and collected

with volatile aqueous pyridine buffers, and the eluant is evaporated. Then the

amino acids within the groups are separated into the D- and L-enantiomers on a

reversed phase column with N,N-di-n-propyl-L-alanine and cupric acetate in the

aqueous mobile phase. Subnanomole sensitivity is achieved by postcolumn derivati-

zation with o-phthaldialdehyde and subsequent fluorometric detection. Proline is

detected by postcolumn derivatization with ninhydrine.

We are now in the process of extending the method to compounds other than the

protein amino acids. Examples are: 1. a-Methyl-a-amino acids which have gained

interest in the study of antibiotics, as enzyme inhibitors, in research on the

origin of life and as constituents of organic matter from meteorites. 2. y-Methyl-

glutamic acid, which is of interest for the study of the mechanism of certain

enzymatic reactions. Y-Methyl-glatamx acid has two asymmetric carbon atoms and

its two diastereoemrs were each separated into a pair of enantiomers. Application

to various analytical problems is described.

1. E. Gil-Av, A. Tishbee and P.E. Hare, J.Amer.Chem.Soc., l_02_, 5115 (1980).

2. S. Weinstein, M.H. Engel and P.E. Hare, Anal.Biochem., 121, 370 (1982).

1- 35 -

ISOLATION AND ASSIGNMENT OF CONFIGURATION OF THE DIASTEREOMERIC tvans-CHLORO

(N,N-DIMETHYL-D-PHENYLGLYCINE)(3-ETHYLCYCLOPENTENE) Pt11 COMPLEXES

By P.A. Ramaiah and E. Gil-Av

Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel

Following previous work on the resolution of chiral racemic olefins via their

diastereomeric Pt complexes, we now report on experiments with the title compounds (I).

Each of the enantiomers of 3-ethylcyclopentene (II) can form with Pt two diaste-

reomers, since each face of the double bond can coordinate with the metal, and rota-

tion around the axis passing through the unsaturated carbons is hindered. Indeed, by

HPLC of (I) on silica gel with n-C6H /Cf^CU/iPrOH (80/10/1), as eluent, 4 peaks

were observed, corresponding, respectively, to the consecutively eluting compounds1 4 3 4I -I , with I and I overlapping partially. By liberating active II with KCN from

1 4 2 3isolated complexes, I and I were found to contain R-(+)-II, and I and I S-(-)-II.

1 2On standing in CHC1_, pure I and I were, respectively, equilibrated to a mixture of

I4/!1 (1.5/1.0) and I2/I3 (2.0/1.0).

As in the more stable diastereomer, the approach of the Pt to the double bond

must be easier, the following assignment can be made for the configuration at C. and

C2: I1-1S,2R,3R; I2-lS,2R,3S; I3-1R,2S,3S; I4-1R,2S,3R.

Analogous structures represent

I2(1S,2R,3S) =5lI3(lR,2S,3S)

NMR (6, ppm): CH2CH_3(t) centered at:

I1 1.169; I4 1.009; I2 0.981;

I3 1.197.

The NMR data are in agreement with the downfield shift reported in the litera-

ture for a methyl group close to Pt.

Pure S-(-)-II (1.2 mg) was obtained from I2. Its [a]30 -130° ± 5° (c 0.100 in

CC1.) confirms the calculated value given by Mislow for a sample of S-(-)-(II)

synthesized from (-)-2-cyclopentene-l-acetic acid of known optical purity.

1. M. Goldman, Z. Kustanovich, S. Weinstein, A. Tishbee and E. Gil-Av, J.Am.Chem.Soc.,104, 1093 (1982.

2. KTMislow and I.V. Steinberg, ibid., 77, 3807 (1955).

1- 36 -

Correlation between Circular Dichroism and the AbsoluteConfiguration in the 3-Alkylcyclopentene System.

A. Ramaiah and E. Gil-Av

Department of Organic Chemistry, The WeizmannInstitute of Science

and

Aharon Gedanken

Department of Chemistry, Bar-Ilan d ivers i ty .

The circular dichroism and absorption spectra of (P.)-3-irethylcyclopentene wasmeasured in the gas phase and we were able to assign the spectrum on the basis ofab-initio SCF calculations. *• The first two transitions were assigned as I! -* 3sRydberg and a valence II •+• II*. i t is well known that in solution the Rydbera transi-tions, undergo substantial blue shifts. Therefore any atteirpt to correlate CD andabsolute configuration of olefins in solutions is subjected to the problem that thefirst two transitions might overlap and cause ambiguous conclusions.

In order to determine whether both transitions are sensitive to the absoluteconfiguration or not, we have measured the absorption and CD of S-(-)-3-ethylcyclo-pentene. The optically enriched compound was obtained by attacking the racemicolefin with an insufficient amount of (+) diisopinocampheyl borane. The a(observed) = -35° corresponding to the e.e. of 26%. The results show that bothtransitions are sensitive to the absolute configuration.

References

1. M. Levi, D. Cohen, V. Schurig, H. Basch and A. Gedanken, JACS 102, 6972 (1980)

1- 37 -

THERMAL ACID-CATALYSED REARRANGEMENTS OF TRANS METHYL CHRYSANTHEMATE.

Zeev Goldschmidt and Bernard Crammer, Department of Chemistry, Bar-Ilan

University, Ramat Gan.

Raphael Ikan, Department of Organic Chemistry, Hebrew University of Jerusalem,

Jerusalem.

Trans chrysanthemic acid is one of the degradation products of the insecticidal

esters known as Pyrethrins. Heating trans methyl chrysanthemate (1) with 50%

aqueous sulphuric acid in heptane at 130 C afforded after three hours two isomeric

methyl esters of hexadienoic acid as the principle products and a mixture of

unsaturated lactones. After 17 hours the labile methyl ester had disappeared

and a mixture of methyl esters and unsaturated y- and 5-lactones were obtained.

Finally after 48 hours the methyl esters were consumed and there remained only

a mixture of unsatured y- and &-lactones.

The mechanism of the thermal acid-catalysed rearrangements of (1) will be presented.

Trans methyl chrysanthemate and the acid-catalysed products were found to have

excellent plant growth retardant activity.

COOCH

1- 38 -

THE FORMATION AftjD CRYSTAL STRUCTURE OF A 12+5JCYCL0ADDUCTShalom Sarel, Nipon Wongvisetsirikul and Shmuel Cohen

The Hebrew University of Jerusalem

Activated vinyl cyclopropane (VCP) when properly substituted could

act as a source of four electrons (2c+2ir) on cycloaddition with electrophilic

olefins (supplying 2ir-electrons) to form adducts containing seven-memberedrings, ([2+5Jcycloaddition), formally resembling I'ne "Diels-Alder Reaction".Unlike the latter, the 12+5]cycloaddition appears to be a multi-stage process,involving an initial electrophilic attack of the electrondeficient oiefin onexo-cyclic double-bond of the VCP to yield a zwitter-ionic species which thencyclizes to form the respective seven-membered adduct.

This communication concerns the formation and the crystal structure(X-ray analysis) of a seven-membered ring containing adduct (2) resultingfrom [2+5Jcycloaddition between trans-isopropenyl-2,2-ethano-l-methylene-l ,-2,3.4-tetrahydronaphthalene C D and TCNE at -20°C. Evidently the cyclopropane

N

ring-opening is coupled with 7-membered ring formation, accompanied by aninversion of configuration. The new bond-forming in the cyclization stagetakes place from a direction opposite to cyclopropane-bond breaking.

1- 39 -

STEREOCHEMICAL EFFECTS ON MASS SPECTRAL HYDROGEN REARRANGEMENTS IN BICYCLICDIONES UNDER ELECTRON IMPACT

Joseph Deutsch and Miriam Chriki

Department of Pharmaceutical Chemistry, The Hebrew University School of Pharmacy,Jerusalem, Israel.

A study has been done to investigate the behaviour of diastereoisomeric compoundsunder electron impact. It is known that mass spectrometric hydrogen migrationsare frequently observed for carbonyl and hydroxylic compounds and that one of thefactors which influences the rearrangement is the distance between the migratinghydrogen atom and the heteroatom to which the hydrogen moves^»2.In our research a bicyclic compound, 1,1'-bicyclohexyl-2,2'-dione (I) is studied.The compound was prepared by oxidation of the corresponding diol and the crudeproduct was measured by mass spectrometer. The mass spectrum was found to bedependent on the length of time the compound spent in the mass spectrometer. Thegreatest differences in the spectra obtained were the ratios between therelative abundances of the ions of m/z 97, 98 and the molecular ion at the m/z 194.Under the assumption that these differences were due to the presence of twoisomers (meso and dl) experiments were done to separate the two diastereoisomersand to study their behaviour. The separation and the mass spectral behaviour oftwo pairs of diastereoisomers will be presented.

l.T.Lesman and J.Deutsch, Organic Mass Spectrometry, 7^,1321-1327 (1973),2.J.Deutsch and M.Chriki, Organic Mass Spectrometry, l_4_,482-484 (1979)

- 40 -

Fluorescent Thiol Labeling and Other Reactionswith Bromobimanes; Glutathione Sulfide (GSG)

by Edward M.Kosower ' , Necham^ S.Kosower*and Annette Radkowsky

Department of Chemistry, Tel-Aviv University,Ramat-Aviv, Tel-Aviv, Israel, 69978,

Department of Chemistry, State University of New York,Stony Brook, New York, USA 11794 and

^Department of Human Genetics, Sackler School of Medicine,Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel 69978

Bromobimanes are extremely useful for fluorescent labelingof reactive thiols in biological and biochemical systems. Thelabeling is rapid at physiological pH and the products arenormally very photostable. Monobromobimane is effective on intactcells while the positively charged monobromo-trimethylammonio-bimane is used for lysed cells such as red cell ghosts. The bis-bromobimanes can label or cross-link proteins, as well as lead toother unusual reactions due to the intervention of bridgedsulfonium ion intermediates. The reaction of a bis-bromoethylbimane with glutathione produces the new compound, glutathionesulfide (GSG).

- 41 -

TAUTOMERISM IN DIHYDRO-1,3,5-TRIAZINE SYSTEMS

A.L. Weis

Department of Organic Chemistry, The Weizmann Institute of Science,

Rehovot, Israel

The first observation of tautomerism of alkyldihydrotriphenyl-1,3,5-

Lines (I) and definitive structural as:

and 3,4-dihydrocompound (IB) has been made.

triazines (I) and definitive structural assignment of the tautomeric 1,4-(IA)

PhwR

HIA

R = Me, E t , Bu" , Bu*, Ph

1 13Spectral(IR, UV, H and C dynamic NMR) correllations have been investigated

and experimental evidence concerning the tautomerism of IA and IB was shown

to be temperature, solvent and concentration de^andent. Comparison with

2tautomerism of 1,4- and 3,4-dihydropyrimidines will be done.

1. R.M. Anker and A.H. Cook, J. Chem. Soc., 1941, 323; L.S. Cook and B.J.

Wakefield, J. Chem. Soc., Perkin Trans. 1, 1980, 2392; L.S. Cook, G. Prudhoe,

N.D. Venajak and B.J. Wakefield, J. Chem. Research (S), 1982, 113.

2. A.L. Weis and F. Frolow, Chem. Commun., 1982, 89; A.L. Weis, Tetrahedron Lett.,

1982, 449; A.L. Weis and F. Frolow, Heterocycles, 1982, 493.

- 42 -

Photochemical Behaviour of Biased Homo-conjugated

Ketones: 2-Methy1spiro[5.5]undeca-l,3-dien-r-one

Jakob Zizuashvili and Benzion Fuchs

Department of Chemistry, Tel-Aviv University

Ramat-Aviv, Tel-Aviv 69978, Israel

Abstract: The t i t l e compound (2J was synthesized and i ts photochemically

induced transformations were investigated. Interesting wavelength effects

were registered and mechanistic pathways are put forward, as affected by

the structural features of the homo-conjugated ketone (2 ) .

"l.(CH20H)2/H+

2.LAH

1 .3.H

(J)311 - 0.08

(I)3 3 8 •= 0.07

Scheme

254 nra

254 nm310 nm

310 nm

350 nm

0 CH,

(25%)

(71%)

(13*) |J>311 - 0.016

(60*) (J)338 • 0.023

0 CH,

- 43 -

SURFACE EFFECTS ON CONFORMATION AND SPECTRA OF DIBENZOTROPONE ADSORBED ON

VARIOUS MONTMORILLONITES

Z. Grauer^, D. Avnir^, S. Yariv^ and L. Heller-KallaitC}

The Departments of Organic Chemistry^ , Inorganic and Analytical Chemistry^ (c)

and Geologyv J , The Hebrew University of Jerusalem, Jerusalem 91904, Israel.

As part of our study of surface effects on the photochemistry and photophysicsof adsorbed molecules, we have investigated conformational electronic and vibra-tionic changes in dibenzotropone (DBT.r) adsorbed on montmorillonites. The electronicspectra of \_ in various solvents are all within the UV range. Shifts into thevisible occur only in very strong acids, due to the formation of the aromatic planartropylium cation 2_. Red shifts to the visible range, with a maximum at 380 nmwere observed upon adsorption on various montmorillonites. The following monoionicmontmorillonites were studied: Na+, Cs+, Mg++, Cu++, Fe+3, Al+3. The degree of shiftis dependent on water content and on the polarising effect of the exchangeable cationon the water acidity in the interlayer space. Thus, the red shift was even stronger(down to 420-480 nm) in the Cu, Ni, Al and Fe montmorillonites, when subjected toheating (100°C) under vacuum, whereas Na, Cs and Mg montmorillonites remainedunaffected. IR measurements showed the formation of a hydrogen bond between thecarbonyl and the acidic hydration shell of the exchangeable cation. The positivearomatic moiety so formed is stabilized by ir interactions with the oxygen sheet ofthe clay. . The organic molecule assumes a planar conformation, and tends to orientparallel to the clay layers. X-ray diffraction studied showed that the basal spacingsof the DBT-'clay associations, depend on the number of water and DBT sheets (one ortwo) ranging from 12.1 A* to 20.4 A*. The lower value represents a single water andDBT sheet, and the higher value two DBT and two water sheets.

1- 44 -

ORTHO LITHIATIONS OF ARENESULFINIC ACIDS. NEW METHOD FOP ELECTROPHILIC

AROMATIC SUBSTITUTION

Samuel Braverman and J.C. Martin

Roger Adams Laboratory, School of Chemical Sciences, University of Illinois,

Urbana, Illinois 61801.

The ortho lithiation of various benzene derivatives using rr-butyllithium

has been studied extensively in the past. Prompted by the recent results

obtained on the ortho lithiation of arenesulfonic acids, we have investigated

the ortho lithiation of arenesulfinic acids.

£-BuLi/THF55 >

-78

HgX

1) E

2) HgX,

H

Treatment of p-toluenesulfinic acid with 2,2 equivalents of n_-BuLi in

THF at -78° results in a fast and quantitative dilithiation of the acid to

give the ortho dilithium derivative 2_, as indicated by nmr spectral evidence

after quenching with D-O. Electrophilic substitution reactions ortho to the

sulfinate group can be easily performed by direct addition of the electrophile

to the THF solution of 2_. Desulfination of the substitution product and con-

version to an arylmercuric halide (3) can be easily achieved by heating with

mercuric halide salts. The arylmercuric halides _3. c a n b e used as synthetic

intermediates or can be protonated to the meta-substituted toluene 4.

The use of the sulfinic acid group as a directing and activating group

for aromatic substitution under mild conditions, coupled with i ts subsequent

removal, as described above, represents a new and potentially useful method

for the synthesis of substituted aromatic systems which are otherwise

difficult to obtain. A number of other synthetic schemes based on the di-

lithium intermediate 2_, and the chemical versatility typical to the sulfinate

group will also be considered.

1. For a leading reference, see: G.D.Figuly and J.C. Martin, J. Org. Chem.,45 3728 (1980) .

1- 45 -

SKELETAL REARRflNGEMENT OF A 2,6-DITHIAADAMANTANE-2,2,6,6-TETRAOXIDE DERIVATIVE

DURING THERMAL AND PHOTOCHEMICAL SULFUR DIOXIDE EXTRUSION

Samuel Braverman, David Reisman, Meir Freund

Department of Chemistry, Bar-IIan Unviers i ty , Ramat-Gan

Dov Rabinovich and Fe l ix Frolow

Department of S t r u c t u r a l Chemistry, The Weizmann I n s t i t u t e of Science, Rehovoth

Recently, we have repor ted t h a t bis-y-y-dimethy 1 a l leny 1 sulfone undergoes a

novel and f a c i l e carbanionic cyclodimerizat ion t o the 2,6-dithiaadamantane b i s -

sulfone de r iva t ive 1. Su rp r i s ing ly , i t was a lso found t ha t compound 1_ shows a

s t rong u l t r a v i o l e t absorption a t Xmax = 236nm with e^29000 i n a c e t o n i t r i l e although

none of i t s it systems are conjugated. 2 In view of t h i s observa t ion , as wel l as the

considerable recent i n t e r e s t in the pyrolysis of cycl ic sulfones as a synthet ic

method for the preparation of cycl ic and po l i cyc l i c hydrocarbons , we have i n v e s t i -

gated the thermal and photochemical elimination of sulfur dioxide from disulfone 1^,

H(D)

-2S0, hv

Direct i r r ad i a t i on of di t h i aadaman tane 1_ in ace ton i t r i l e a t 254nm resu l t s in

the extrusion of only one molecule of sulfur dioxide, together with a double a l l y l i e

rearrangement of the second sulfonyl group, and formation of the t r i c y c l i c sulfone 2.

Although the spec t ra l evidence was in accord with the assigned s t ruc ture of 2_, un-

equivocal s t ruc ture proof was obtained by X-ray crystal lographic analys is . In con-

t r a s t to the photochemical r e s u l t s , pyrolysis of compound 1 a t ca. 300° r e su l t s in

extrusion of both S02 groups and formation of the b icyc l i c hydrocarbon 3^, with

essen t i a l ly the same rearranged carbon skeleton as in product 2_. The question

whether the f i r s t SO- extrusion, which i s common to both processes , i s preceded or

followed by the ske le ta l rearrangement, as well as other mechanistic de t a i l s w i l l

be considered.

1. S. Braverman, D. Reisman, M. Sprecher, D. Rabinovich and F. Frolow, TetrahedronLetters 901 (1979).

2. S. Braverman, D. Cohen, D. Reisman and H. Basch, J.Amer.Chem.Soc.,102, 6556 (I960)3. For a review see F. Vogtle and L. Rossa, Angew.Chem.Int.Ed.Engl. _18, 515 (1979).

1- 46 -

DYNAMIC NMR INVESTIGATION OF THE TAUTOMERISM IN DIHYDROPYRIMIDINES

A.L. Weis and Z. Porat

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot, Israel

Recently we reported the first observation of annular tautomerism in the

1 2dihydropyrimidine systems , as well as the crystal structure of 1,4- and 1,6-

dihydrotautomer of dihydropyrimidines and the factors involved in recognition

4of such tautomerism .

In order to obtain further information about this type of tautomerism, we

have carried out: a) A dynamic NMR study in chloroform solutions. The calculated

kinetic activation and thermodynamic parameters will be discussed, b) Solvent

polarity dependence. Chemical shifts and relative populations of the tautomers

have been obtained in different solvents at low temperatures; the relative

concentration of 1,4-dihydrotautomer has been shown to increase with the solvent

polarity, c) Concentration dependence on the rates of proton exchange was found

to indicate the intermolecular character of the proton transfer.

1. A.L. Weis, V.P. Mamaev, Izv. Sib. Otd. Akad., 1975, 148; Chem. Abstr., 1976, 12179v;A.L. Weis, 8th Int. Congress of Heterocyclic Compounds, Graz/Austria, 1981, 469.

2. A.L. Weis, F. Frolow, Chem. Commun., 1982, 89.3. A.L. Weis, F. Frolow, Heterocycles, 1982, 494.4. A.L. Weis, Tetrahedron Letters, 1982, 449.

- 47 -

COMPLEXATION OF ORGANIC COMPOUNDS TO CYCLODEXTRINS - ARTIFICIAL MODELS FORSUBSTRATE-RECEPTOR INTERACTIONS IN ENZYMES

Z a f r i r Goren, P h y l l i s Dan and Itamar Wil inerDepartment of Organic Chemistry, The Hebrew Unive r s i ty of Jerusalem

Jerusalem 91904, I s r a e l

The activity of enzymatic reactions is attributed to unique interactions ofthe substrates with the enzyme receptor si tes. The strong association ofsubstrates to these receptors originates from precise fitness of the substrateto the receptor s i te . In addition remote functional groups of the enzyme proteinbackbone participate in the complexation process.

We attempt to utilize cyclodextrins (CD) as artificial receptors mimickingthe functions of enzymes. CD's are cyclic poly sugars composed of 6, 7 or 8glucose units linked by a 1,4 glycoside bond (a, 3 or y-CD respectively). Theircyclic structure forms a cylindrical hydrophobic cavity surrounded by polarCH-groups. A variety of organic substrates associate with the CD-cavity bymeans of hydrophobic host-guest interactions.1*2 The association constants(Ka) are determined spectroscopically. We have examined the enhancement of thehost-guest interactions by introducing substrate-receptor anchoring sites thatfunction cooperatively with the hydrophobic cavity in the complexation process.For example, the association of ferrocene carboxylic acid (1) (Ka=1.3xlO2 M"1)is ca. 300 times stronger than that of ferrocene (2). This enhancement isattributed to the participation of hydrogen bonds between the substrate, (1_),and the CD-hydroxyl groups periphery.

(1) R = -C02H

(2) R = K B-CD

Different aspects of participation of substrate functional groups in thecomplexation, and controlling the reactivity of these substrates by means ofCD-receptors will be discussed.

1. W. Saenger, Angew. Chem. Int. Ed. Eng. Jj^, 344-362 (1980).2. I . Tabushi, Ace. Chem. Res. 15, 66-72 (1982).

- 48 -

CONTROL OF PHOTOINDUCED ELECTRON TRANSFER REACTIONS IN POSITIVELY CHARGED CTABMICELLES, DODB VESICLES AND ZrO2 COLLOIDS

Yinon Degani and I tamar Wi l ine rDepartment of Organic Chemistry, The Hebrew Unive r s i ty of Jerusa lem

Jerusalem 91904, I s r a e l

Photosensitized electron t ransfer reactions are of in t e re s t as a means of so la renergy conversion and s to rage . 1 We have examined the photosensit ized reduction ofanthraquinone-2-sulfonate ( la) and (lb) in pos i t ive ly charged CTAB micelles andDODB ves ic l e s . In these reac t ions , Zn-TPPyS°, (2) , i s used as sens i t i ze r and cysteineas electron donor. The photoreduction of (La) in CTAB micelles and DODB vesic les i s5 and 10 fold enhanced as compared to the homogeneous aqueous phase. This effect i sa t t r i bu ted to the s t ab i l i za t ion of the intermediate photoproducts (eq. 1) against thethermodynamically favoured recombination by means of e l e c t r o s t a t i c in terac t ions withthe charged in te r face . The higher effect of the DODB vesicles i s a t t r ibu ted to t he i rhigher surface po t en t i a l . Subst i tut ion of (.la) with (lb) in CTAB micelles substan-t i a l l y enhances the quantum yie ld of AQHS" formation (W~= 0 .26) , a 26 fold enhancementas compared to the homogeneous solut ion. This enhancement i s a t t r ibu ted to strongassociat ion of the electron acceptor to the micellar interface due to inforporationOf the counter ion in to the micellar aggregate. Consequently, the recombinationprocess (eq. 1) i s effect ively retarded by the e l e c t r i c po t en t i a l .

(eq. 1) Zn-TPPyS° + AQS' Zn-TPPyS

(la) M+ = Na+

(lb) M+ = +NH3-C16H33

A similar effect is achievedwith positively charged ZrO2 colloids.2 With thiscolloid the photoreduction of AQS", (la), and anthraquinone-2,6-disulfonate wasaccomplished with Ru(bipy)2(CN)2 as sensitizer and cysteine as electron donor. Noreaction is observed in a homogeneous aqueous phase. The success in performing thereaction in the Z1O2 colloid is attributed to the stabilization of the photoproductsagainst the degrative recombination (eq. 2) that facilitate the subsequent oxidationof cysteine.

(eq. 2) Ru(bipy)9(CNU + AQS J ZrO- ? • WfRu(bipy)7(CN)9 + AQHST [ ZrO,

1. I. Willner et al. in "Inorganic Reaction in Organized Media", ACS Sym. Ser. No. 177(1981).

2. I. Willner and Y. Degani, Isr. J. Chem. in the press (1982).

1- 49 -

ANODIC OXIDATION OF ALLENIC HYDROCARBONS IN CHjCN

James Y. Becker and Baruch Zinger

Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva, Israel.

The anodic oxidation of a variety of alkyl-substituted allenes, terminal and in-

ternal ones, has been investigated in acetonitrile. All compounds studied were

found to undergo 2e~ oxidation followed by nucleophilic attack by acetonitrile and

water molecules, to form products containing at least two of the following function-

al groups: C=C, NHCOCHj, C=0 and OH.

The effect of various parameters (concentration, electrolyte, oxidation potential,

temperature and anode material) on the electrooxidation of a model compound (1,2-

nonadiene) has been studied and a general mechanistic scheme is presented and

discussed.

Under appropriate conditions (higher substrate concentrations, elevated potentials

and in the presence of BF.~) heterocyclic compounds were formed, incorporating an

allenic molecule with two acetonitrile ones.

- 50 -

EVIDENCE OF HYDROXIDE ION EXTRACTION IN THE PHASE TRANSFER

CATALYZED ISOMERIZATION OF ALLYBENZENE

Marc Halpern, Yoel Sasson and Mordecai Rabinovitz

Department of Organic Chemistry and the Casali Institute of

Applied Chemistry, The Hebrew University of Jerusalem,

Jerusalem 91904, Israel

In many organic reactions requiring a base, the classical bases (alkali

metal alkoxides, amides and hydrides) have been replaced by the more convenient

aqueous sodium hydroxide in the presence of a phase transfer catalyst. The

mechanism of such PTC/OH" systems has been the subject of much discussion.

It is generally accepted that deprotonation of an organic substrate by the

hydroxide ion occurs at the interface, and the resulting organic anion is drawn

into the bulk organic phase by the catalyst for subsequent reaction. A second

possible mechanism is extraction of the hydroxide ion into the organic phase

by the catalyst followed by substrate deprotonation and reaction.

We have investigated the base catalyzed isomerization of allylbenzene under

PTC/OH" conditions. Examination of the dependence of the pseudo first order rate

R4N+Br~

Ph-CH?-CH=CH7 ^ N a 0 H » Ph-CH=CH-CH, (trans and cis)

75 °,Toluene

constant on stirring speed, catalyst structure, catalyst concentration, temperature,

aqueous hydroxide ion concentration and catalyst counterion provides strong evidence

for the applicability of the hydroxide ion extraction mechanism. Our results will

be presented and the criteria for PTC mechanism determination will be discussed.

1- 51 -

Geometrically controlled diraerisation or acetone-

G-methyl oxime, Uses for pyrrole synthesis

Shimon ohatzmiller, KLiezer Baiiar and viamy Lidor

Department of chemistry Tel-Aviv university, ctaniat-

Aviv - fel-Aviv

Lithiation of acetone O-methyl-oxime 1_ with n-Buli

in IiIF / hexane at -6cj*C followed by reaction of

lithiated 1[ with molecular iodine at -o #<J ^ives 2

in high ( over 95/> ) yield and high Z,Z isorner

concentration. Treatment of 2 v/itli dilute acid affords

the thermodynamically more stable di oxime j5.

n H ...if

LA,, (LJMonolithiaUion of both 2 and %. at -0r3*-' .vud suosessive

alkylation gives 4 and 6 respectively, -.cxd hydrolysis

of 4 and 6 gives the pyrrole derrivaliives 2 mi<^ L

respectively, i'hese O-wmet l ethei c can be hydrofseuoliced

to the free pyri'oies.

1- 52 -

PREPARATION OF SUBSTITUTED PIPERIDINOCYCLOHEXANECARBONITRILES. A NEW

VARIANT OF THE STRECKER REACTION.

Asher Kalir, Jean-Marc Kamenka and Patrick Geneste

Israel Institute for Biological Research, Ness Ziona, Israel and *Laboratoire

de Chimie Organique Physique Appliquee, Ecole Nationale Superieure de Chimie,

34075 Montpellier, France.

Aldehydes and ketones condense with secondary amines and hydrogen cyani-de to dialkylaminocarbonitriles ( Strecker reaction ) .

This reaction failed with 2-alkylated cyclohexanones 1, probablybecause of steric hindrance.

HCN 7/

The desired compound £ has been easily prepared by cyanosilylation of1_ and reaction of the substituted trimethylsilyloxycyclohexanecarbonitrile 6_with an excess of piperidine in the presence of an acid catalyst. ~~

0I!aR

+ Me3SiCN

The cyano group in £ could be exchanged by an aryl substituent to givederivatives of phencyclidine.

1- 53 -

NOVEL SYNTHESIS OF VTNYLALLENES AND 1,3-DIMETHYLENECYC3JOBUTANES TRHOUGH BASE-

CATALYZED DIMERIZATION AND CYCLODIMERIZATION OF ALLENIC SULFONES

Samuel Braverman, David Reisman and Meir Freund

Department of Chemistry, Bar-Ilan Univers i ty , Ramat-Gan

The thermal cyclodimerizat ion of a l l enes t o 1,2-dimethylenecyclobutanes has

been of long-standing i n t e r e s t . Recently, we have reported a novel base -cata lyzed

cyclodimerizat ion o f d i a l l e n y l su l fones t o 2,6-dithiaadamantane 2 , 2 , 6 , 6 - t e t r a o x i d e

d e r i v a t i v e s , and explained t h e i r formation by a "carbanion walk mechanism", i n

which an allenic a-sulfonyl carbanion in i t ia tes a series of four consecutive inter-

intramolecular Michael additions, with final return of the negative charge to i t s

original carbon. In continuation, we have tested this mechanism on monoallenic

1) n-BuLi/THF<.0° ^ _/ l)n-BuLi/THF . \

?2) Ho0 f 1 U Reflux

H

1 Z = ArSO 2. 1

Treatment of YfY-dimethylallenyl aryl sulfone 1 with n_-BuLi in THF at 0° re-

sulted in dimerization to vinylallene 2, However, i f the same reaction i s run at

reflux temperature instead, the expected cyclodimer _3 i s obtained. Obviously, forma-

tion of a 1,3-dimethylenecyclobutane requires a higher activation energy than the

formation of 2,6-dithiaadainantane skeleton. Besides i t s mechanistic significance,

both reactions are of considerable synthetic u t i l i t y , especially after reductive

desulfurization. For example, vinylallenes have been of particular interest recent-2

ly due to their facile [1,5] sigmatropic rearrangement to conjugated trienes ,

while the synthesis of 1,3-dimethylenecyclobutanes nicely complements the thermal

cyolodimerization of allenes. Finally, since allenic sulfones are readily obtained

by [2,3] sigmatropic rearrangements of propargylic sulf inates, the above reactions

are a very convenient approach to the t i t l e compounds.

1. S. Braverman, D. Reisman, M. Sprecher, D. Rabinovich and F. Frolow, TetrahedronLetters, 901 (1979).

2. C.G. Knudsen, S.C. Carey and W.H. Okamura, J. Amer. Chem. Soc., 102, 6355 (1980)and references cited therein. For a general review on vinylallenes see, I.Z.Egenburg, Russ. Chem. Rev., £7 470 (1978).

- 54 -

THE SYNTHESIS OF NEW 3,4-DIMETHYLENETHIOLANE DERIVATIVES:

POTENTIAL TETRAMETHYLENEETHANE PRECURSORS.

Samuel Brave man and Meir Freund

Department of Chemistry, Bar-I lan U n i v e r s i t y , Eamat-Gan,

Recent ly , we have reported a f a c i l e s y n t h e s i s o f the novel condensed

heterocycle l , l ,4,4-tetramethyl-lH,4H-thieno[3,4-<?]thiophene (1) , involving an £

pr ior i unexpected reaction between lithium methoxide and Y,Y~dimethylallenyl t h i o -

cyanate. Prompted by the recent in teres t in the synthesis of 3 ,4-dia lkyl idenethio-

lanes in general, and the ir use as precursors of tetramethyleneethane b iradica ls in2

part icular , we have invest igated the u t i l i t y of 1 as a s tar t ing material for the

preparation of such systems. As can be seen from the Scheme, compound ^prov ides a

convenient entry to the preparation of the new 3,4-dialkylidenethiolane derivatives

4 and 5.

Scher,e

l)Bro ,CCl ;

• >

I) 50 fCH OH

1) LAH.A1C1.

2) ra-CPBA

1) n-CFBA.O"

1) A

H-

\ / s

I t i s noteworthy that conpound £ i s separated from the tetramethyleneethane

derivative £ by a mere sulfur dioxide bridge, and may therefore serve a suitable

precursor for this elusive biradical intermediate. The effectiveness of the above

scheme for the preparation of the t i t l e compounds wi l l be compared with that of

existing methods.

1. S. Braverman, M. Freund, and I . Goldberg, Tetrahedron Letters, 21 3167 (1980).

2. A.C. Talma, J.G.M. Goorhuis and R.M. Kellogg, J. Org. Chem., 45_, 2544 (1980)and previous references cited therein.

- 55 -

THE REACTION OF BENZYLIDENACETYLACETONE WITH BENZAMIDINE

A.L. Weis and M. Bernstein

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot, Israel

In a thorough reinvestigation of the condensation of benzylidenacetylacetone

(I) with benzamidine (II) (S. Ruhemann, 1903) we have shown, that the initial

product of the reaction is compound (III), which, depending on the condition of the

reaction, may then be transformed into dihydropyrimidines, either (IV) or (V).

0

The mechanism of these cyclizations, the influence of the ratio of starting

materials on the reaction course, the catalyst and solvents used as the reaction

medium, the aromatization possibilities of the formed ring, and other factors

which favour or preclude the formation of the pyrimidine nucleus, will also be

discussed. This sequence of reactions enabled us to prepare the functionalized

derivatives of dihydropyrimidines at position 5.

- 56 -

SYNTHESIS AND CRYSTAL STRUCTURE OF

2,4-DIAZA-6,7-BENZO-8-OXABICYCLO[3.3.1]-NONANES

* j. * *

A.L. Weis , F. Frolow , M. Bernstein and J. Fahima•V 4,

Departments of Organic and Structural Chemistry

The Weizmann Institute of Science, Rehovot, Israel

As part of a study of convenient models for determination of structure and

tautomerism in dihydropyrimidines, we attempted the synthesis of compounds of type

Z_, where an ortho-hydroxy group was expected to stabilize the 1,4-dihydrotautomer

by intramolecular hydrogen bonding. Using standard procedures for preparing dihydro-

pyrimidines (condensation of ot,3-unsaturated carbonyl compounds 1_ with amidines 2_

in benzene with azeotropic removal of water), we isolated a colorless crystalline

product in 80-90% yield.

R=Me;ph

HO

Although the initial analytical data and parent ion peak in mass spectrum

fitted that of the desired 3_, IR and NMR studies suggested the novel tricyclic

bridgehead structure A_ for the product. This was confirmed by an X-ray diffrac-

tion study.

- 57 -

THE FEACTION OF CARBENES WITH CTCLOHEPTATRIENE-Fe (CO) 3 COfTLEX

Shlomo Antebi and Zeev Goldschmidt

Department of Chemistry, Bar-Ilan Universi ty, Ramat-Gan

Previously we have reported tha t der ivat ives of the cycloheptatriene-Fe (CO) ,

complex (CHTC) (1) undergo cycloaddition react ions with unipar t icu la te e l e c t r o -

ph i les such as tetracyanoethylene (TCNE), N-plenyl- tr iazol inedione (NPTD) and

diphenylketene to give a var ie ty of b i cyc l i c compounds.

Here we wish to repor t a simple approach for the preparat ion of b icyc lo[5 .1 .0] -

octadiene systems by cycloaddition of carbenes to CHTC. Thus the addition of

dichloro- and dibromocarbene under phase t rans fe r conditions resul ted in a smooth

conversion of CHTC to 2_ and _3, respect ive ly . Also acylcarbenes generated from

the corresponding diazo compounds by copper catalysed thermal reaction cycloadd

to CHTC. However, while e thy l diazoacetate gave the expected product 4_ benzoy]

diazomethane afforded a o,II-ally 1 complex.

F« (COl

^ X=Y= CA

2 X=Y= Br

4 X= COOEt, Y= H

1- 58 -

A NEW INDICATOR SUBSTRATE FOR CLASSIFICATION OF NUCLEOPHILES.*

Ehud Keinan and Zeev RothDepartment of Organic Chemistry, The Weizmann Institute of Science,

Rehovot, Israel

A qualitative classification of nucleophiles with respect to theirinteraction with ir-aHyl palladium complexes is suggested, based onregiochemical selectivity. The indicator substrate ± reacts in threedifferent modes with various nucleophilic reagents:

Nu

Nu

OAc

Pd(PPh3)4Nu

Ph'

CN

CN

This pronounced regioselectivity can be correlated to stereospecificityphenomena observed in these reactions.

An explanation is suggested, based on the formation of unsymmetricalir-ally! palladium complex as the active intermediate.

1- 59 -

1

REDUCTIVE ELIMINATION OF VICINAL OXYGEN FUNCTION WITHPALLADIUM(o). APPLICATIONS IN WITHANOLIDES INTERCONVERSIONS.

* 1E. Keinan , M. Sahai, and I. Kirson

Department of Organic Chemistry, The Weizmann Institute of Science, RehovotFaculty of Agriculture, The Hebrew University, Rehovot

A highly chemoselective method offered by organopalladium chemistryto reductively eliminate two vicinal oxygen functions, one of which isallylic. The reaction mechanism was investigated by means of NMR spectroscopyby which two defined intermediates were identified. Application of thisprocess in natural products chemistry allowed highly efficient and usefulinterconversions of naturally occuring withanolides:

OH

_ rrAcO

4-Acetoxy Withanolide E

Pd(PPh3)4

OH

OH

Withaperuvin C

As part of the mechanistic investigation the same catalyst,was also used for stereospecific and regioselective amination of naturalwithanolides:

OH I

1

341302 merCU :Dj

E. M E R C K ,

J . C . BINZER ,

BOECKEL & CO. ,

TH. GOLDSCHMIDT

•tra7iV 03-485774 : '"7U

DARMSTADT ,

•

Scientific

for water

•

WEST

nnr«, 47100 m w nir

GERMANY

D^A ' in in ,nmy»

mpia

1 6 .7.71

equipment , R i e l e - Photometers

testing

iiy 71

and diagnostica

i'yi DI^'Y n"»yn

•

ANKOR

SCIENTIFIC EQUIPMENT & SERVICES LTD.

TRACOR INSTRUMENTSFINNIGAN MATWESCAN INSTRUMENTSANALECT INSTRUMENTSALLTECH ASSOCIATESJOBIN YVON INSTRUMENTS

BIOTRONIK GMBH

r> O Ft 34'» G I V A I A V I M •", 1 IO?

Gas/Liquid ChromatographyMass SpectrometersIon ChromatographyFT-IR SpectrometersChromatography Supplies

Raman SpectrometersPlasma SpectrometersAmi no Acid Analyzer

nniyn7

ltdCHEMICALS FOR LABORATORY AND INDUSTRY36016 i n • 624361-2-3-4."7D • 22 TUZTin TH • 66183TEL-AVIV 66183 • 22. HARAKEVETH STR • TEL 624361-2-3-4 • PO B 36016

DU'TUDWKU/Jll

fnjmn '37

LARGE VARIEDIN

LOCAL STOCK

IMPORT OFROW MATERIALPER CUSTOMER

ORDER

LABORATORYREAGENTS

(RIEDEL-DE HAEN)

FINEINDUSTRIALCHEMICALS

DELIVERYSERVICE

TECHNICAL ADVISE • M/l*I7n \W

numn1? nnnrn xiimnSPECIAL DISCOUNT FOR LARGE ORDERS

1 ••

iimiconUltrafiltration

Microfiltration

Columns

AdjustableCapacity Columns

Small ScaleAcrylicProduction Column

Fixed CapacityColumns

Intermediate ScaleAcrylicProduction Column

Large ScaleAcrylicProduction Column

Small ScaleGlassProduction Column aoi4°.T.n 26 ahniYiK ' m

" ^ ^ - . 3-2^66

Large ScaleGlassProduction Column

BBCSROWNBOVERi

GOER;METRAWATT

Recorders forLaboratoryand Workshop

M"ya opmntu' r. an

6014 .-r.n 25 rrnin'riK 'm

62488 3i3N-7n3-2266 D|77U24821311370

111111 • 111 • i • 111 • • • • 1 1 1 • 1 1 • i • • • (Ii,;>

1

INORGANIC CHEMISTRY

- 60 -

LUMINESCENT SOLAR CONCENTRATORS FOR ENERGY CONVERSION

Renata Reisfeld, Department of Inorganic and Analytical Chemistry,

The Hebrew University of Jerusalem

The geographical, seasonal and spectral distribution of the terrestrial solar

energy will be described. The concept of non-tracking fluorescent concentra-

tors and the mathematical background for collection and concentration of direct

and diffuse light will be discussed. The single plate, multiple stacks and thin

films doped by one or more colorants will be reviewed. The differences between

inorganic and organic materials will be analyzed. A summary of spectroscopic data

absorption, fluorescence spectra and decay curves of various inorganic ions and

their suitability for fluorescent glass plates will be reviewed. Factors respon-

sible for quantum efficiency will be discussed. Suggestions for new hybrid sys-

tems will be made.

- 61 -

CHEMICAL REACTIONS OF UNSTABLE COMPOUNDSWITH METAL-CARBON BONDS IN AQUEOUS SOLUTIONS

Dan Meyerstein

Chemistry Depts., Ben-Gurion University of the Negevand Nuclear Research Centre Negev, Beer-Sheva, Israel

Short lived transients with metal-carbon bonds have been suggested as inter-

mediates in catalytic systems, e.g. Fentons reaction, and biochemical processes, e.g

diol dehydratase. Pulse radiolysis is a convenient technique for studying rates of

reaction of aliphatic free radicals with transition metal complexes yielding trans-

ients with metal carbon bonds.

LMn + •*• L M ( n + 1 ) — C R

The technique enables also the study of the chemical properties of the metal carbon

bond formed.

Reactions involving complexes of Cr(II), Cu(II), Cu(I), Fe(II) and Co(II)

with a series of aliphatic radicals are reported. Examples of oxidative and reduc-

tive heterolytic as well as of homolytic dissociation of the metal carbon bond will

be presented.

The specific rate of 3-elimination of hydroxyl groups was measured in several

systems, e.g.,

LM-CH2C(CH3)2OH + LM-CH = C f C H ^ + H20

and indications for g-hydride shift was obtained in some systems.

Factors affecting the chemistry of metal-catbon bonds in aqueous solutions will

be discussed.

- 1

- 62 -

brribyno ipon - n n

niann !>«; o ^ p ^ i i p a o^op^amp ipna

TDinn !>y nnoa nt>K nn^A'!? IWK nnni^an nuiDnna pi Kt>

laoa v ^ naiAnn utnayaa nipnj irmiriNn

*mi»aa .D ' j n ^n i oioipi ^ n ^ bis D>t>p>if

">"y vait>Ai>ai vai^Ainna heme -n n^iap no^nn t>e>

nipnIt

- 63 - 0

REACTIONS OF IRON(II) PROTOPORPHYRIN WITH FREE RADICALS. A PULSE RADIOLYTIC STUDY.

Yacov Sorek, Haim Cohen and Dan Meyerstein

Chemistry Departments, Nuclear Research Centre Negev,and Ben-Gurion University of the Negev, Beer-Sheva, Israel

The reactions of iron(II) protoporphyrin, Fe(II)L, with 'CH^CCH^OH,

•CH(CH )OH and e were studied. The results indicate that the reaction witho aq

•CH2C(CH,)2OH is too slow to be studied by the pulse radiolytic technique. Fe(II)L

reacts with e to produce an unstable intermediate which is transformed by aaq c

first order process into Fe(III)L. The reactions observed are probably

(1) Fe(II)L + e" -*• Fe(I)L k = 7 x 109 M " 1 S " 1

aqfollowed by

(2) Fe(I)L + H20 •*• Fe(III)L + H2 k = 4 x io3 s"1

Fe(II)L reacts with *CH(CH )0H radicals to produce a transient which differs

from Fe(I)L probably described by

8 M'V1

(3) Fe(II)L + •CH(CH3)OH •* Fe(III)L - CH(CH3)OH k = 4 x 108

The latter transient decomposes by a first order process with k = 270 S" to yield

Fe(III)L. The reaction observed is probably

H O(4) Fe(III)L - CH(CH3)OH -^-> Fe(III)L + CH3CH2OH

or

(5) Fe(III)L - CH(CH3)OH -*• Fe(I)L + CH3CHO

followed by reaction (2) which is faster. Analysis of the final products will

discriminate between the later reactions.

- 64 - 0

A STUDY OF THE MECHANISM OF FORMATION OF POLYMERIC SPECIES IN THE MASS SPECTRA

OF PENTACARBONYLTRIMETHYLSILYL-ISO-CYANO- COMPLEXES OF GROUP VI METALS

Miriam Cpjocaru and Jacob M.F. Goldschmidt

Department of Chemistry, Bar - I lan Univers i ty , Ramat-Gan, 52100

The mass s p e c t r a of compounds having the genera l ized formula

RRJR"SiNCM(CO)5 [R=H,Me ,Et,NMe2; R'=R"=Me,Et; M=Cr,Mo,W] a l l show s i g n a l s due t o the

presence of peaks (RR'R"SiNCM)2 (CO)..- [n=l-10] and often far weaker s i gna l s due t o

(R'R' R" SiNCM)o (CO),_ [n=l-15] . s i m i l a r phenomena repor ted in the mass s p e c t r a ofJ 15—n

the hexacarbonyls of these metals have been ascr ibed t o ion-molecule r eac t ions (1 ) .

However, as pre l iminary experiments showed t h a t the appearance of the dimeric

species i s r e s t r i c t e d t o qu i t e s p e c i f i c condi t ions , the above mechanism seemed

ques t ionab le . So, i n order t o understand the source of the polymeric species and

the mechanism of t h e i r formation, we undertook a wide-ranging i nves t i ga t i on of the

condi t ions under which these ions are formed. The following parameters were var ied

s y s t e m a t i c a l l y : i n l e t temperature , source temperature , method of i on iza t ion

(e lec t ron impact and chemical ion iza t ion) and ion iza t ion p o t e n t i a l . The changes

in the amounts of the var ious spec ies was followed q u a n t i t a t i v e l y . The r e s u l t s of

these experiments w i l l be presen ted and discussed in d e t a i l .

Contary t o the e a r l i e r p roposa l , evidence support ing a chemical mechanism for

the formation of the polymeric s p e c i e s , as ou t l ined below, was found. The

mechanism proposed i s :

RR'^'SiNCMtCOg ~ 2 — * RRlR"SiNCM(C0)5_n (n=l chief species)

RR'R"SiNCM(CO^_n + RR1 R"SiNCM(CO)5_n, »• (R R1 R"SiNCM)2 (C0>10_n_n, .

The most p reva len t dimeric species formed by t h i s route der ives from n = l ,

n ' * 0 . Of course the e n t i r e fragmentation p a t t e r n of t h i s product and of the o the r

spec ies formed i s observed in the e l ec t ron impact spec t r a .

(1) C.S. Kraihanzel , J . J . Conville and J .E . Sturm. Chem. Commun., 159 (1971),and references t h e r e i n .

- 65 -

Intermolecular Vs. Intramolecular-Electron Transfer Reactionsin Cobalt(III) pentaamine Coordinated to Pyridinyl Radicals

H. Cohen, E.S. Gould, D. Meyerstein, M. Nutkovich and C.E. RadlowskiChemistry Departments, Nuclear Research Center Negev, Ben-GurionUniversity of the Negev, Israel and Kent State University, Ohio USA

Recently several studies have shown that ortho and para substituted pyridinesare good catalysts for reduction of Cobalt(III) pentaammine complexes by europeousions. In order to explain this result the followinq mechanism was suggested :

J 5NHJ + L (1)(2)

+ Lh @ aq + 5NH4Furthermore in systems where the organic ligand L is a pyridinyl ligand coordinatedto a Cobalt (III) center via a carboxylate functional group the reduction of thecomplex involves reduction of the pyridinyl followed by an intramolecular electrontransfer reaction, IET, from the pyridinyl radical to the Cobalt (III) center

(4)

We have investigated the reduction of four Co(NH~),-L (where L is a pyridinylderivative) in order study structural effects on the rate of IET. Aliphaticsradicals produced by the pulse radiolytic technique were used to

reduce the carboxylate bound pyridinyl.

Surprisingly only the bound free radical L.~ exhibed IET, k. = 4x10 SIIIand the other three Co (NH.J,-L; 2 3 reduced another parent complex

Co (NH3)5L via the intermolecular electron transfer reaction :

L (5)

The origin for the different reactivity patterns is discussed.

- 66 -

A NOVEL [Ru4(CO)?(y-CO) (n2,n5,Ti2-INDENYL) (n5-DIHYDROINDENYL)] CLUSTER

Felix Frolow, Avi Efraty, and Amihai Eisenstadt

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot, Israel

The reaction of indene with in boiling methylcyclohexane gave

the expected dimer [(n5-indenyl)Ru(CO) ] as well as a second product which

ultimately characterized as a tetranuclear cluster. The structure of this

cluster and its novel features will be outlined and discussed. The tetra-

nuclear cluster (1) consists of a triangulotriruthenium unit with Ru(4) being

bonded to Ru(3). The near planarity of the Ru. skeleton is best illustrated

by the slight displacement (ca. 0.07 A) of Ru(3) from the plane defined by the

remaining metal atoms. The organic ligands in this cluster consist of seven

terminal carbonyls, two symmetrical bridging carbonyls, three-way bridging

(n2,n5,n2) indenyl, and n5-dihydroindenyl. According to the skeletal electron

pair theory, the Ru(2)-Ru(3) bond in this cluster is formed by an interaction

between a "filled donor orbital" on Ru(3) and a "vacant acceptor orbital"

on Ru(2). This bond, where the electron density appears to be unevenly

distributed, was found to be the longest metal-metal bond in the system.

- 67 -

PREPARATION OF SOME UNUSUAL y-CARBENE COMPLEXES OF RUTHENIUM

Amihai Eisenstadt and Avi Efraty

Department of Organic Chemistry

The Weizmann Institute of Science, Rehovot, Israel

The passing of an acetone-hexane solution of [Ru(CO) (n3-C,H,-) (n5-C H,.)]

(mixture of isomers 1_ and 2) through a deactivated silica-gel column, gave an

unusual y-carbene complex of the type [Ru2(y-CO)(y-n1Jn

3-CHCHCH2" (n5-C H-)-]

(3). This complex is formed by a process involving n3-allyl to y-n1,n3-allylidene

transformation which implicates a-hydrogen transfer or elimination reactions.

Similar transformations were also encountered with some substituted n3-allyl

ruthenium derivatives. The stereochemical aspects of this reaction were ascertained

by examining both then3-allyl substituents and isomers [endo(l) and exo(2)]

effects on the course of the transformation and the nature of the products. The

stereochemistry of products derived from this transforamtion were established,

among other, by means of a comprehensive H and C NMR study.

- 68 - 0

Complexes Of Lithium Salts With The

Macrocyclic - polyether Dibenzo-14-Crown-£f.

TJ. Olsher, E.R. Blout, Department of Biological Chemistry,

Harvard Medical School. Boston, MA. 02115

05. Shoham, W.N. Lipscomb, Department of Chemistry Harvard

University, Cambridge, MA. 02138

Since the discovery that lithium therapy has proven

successful in some patients suffering from mania or biopolar

disorders, there have been many studies on the effect of

lithium in biological systems. The preponderance of these

studies have focused upon (i) determination of the lithium

concentrations in blood plasma and red blood cells of patients

and normal individuals receiving such salts (ii) the mechanism

of lithium transport across biological membranes, (iii) lithium

salts as protein-denaturing agents, and to less extent (iv) the

lithium coordinantion ability.

Because we wish to understand better the lithium coordination

and contribution of the "counter-ion" to many fundamental

properties of such systems, i.e. structure, stability and

selectivity, we undertaken a X-ray diffraction study of the

crystal structure of the macrocyclic-polyether, Dibenzo- 1Zf-Crown-2f,

complexes with LiNCS, LiCIO, and Lil.

In all the complexes the lithium is, at least, penta-

coordinated.

The "counter-ion" effect has been elucidated.

This study enables us to design lithium-selective-membranes

for medical and industrial purposes.

- 69 - 0

EXTENDED DONOR-ACCEPTOR MOLECULAR COMPOUNDS BETWEEN THIONES AND CHAINSOF BIS(IODINE) MOLECULES.

F.H. Herbstein and W. Schwotzer

Department of Chemistry, Technion - Israel Institute of Technology,Haifa, Israel.

Donor-acceptor molecular compounds between sulphur-containingorganic molecules and single molecules of bis(iodine) are well known1'2.From preparative work and crystal structure determinations we find thatthere are two series of such molecular compounds containing more thanone bis(iodine) per donor molecule, the known compounds constitutingthe first members of the two series.

Unsymmetrical Chains Symmetrical Chains

dithizone**I_ merocyanine#l*merocyanine4 1

etu*«(I2)2 etu«I2'I2»I2»etu i2

dithizone»I «I 'I,,»I «IIL I I Z Z

*dithizone is 1,5-diphenylthiocarbazone; etu is ethylenethiourea

We find an approximately hyperbolic relation between d(S—I) andd(I—I) (in the I2 molecule directly linked to S). In the strongestinteractions d(S 1) a. 2.49 A, approaching the covalent bond distanceof d(S—I) = 2.37 A; concomitantly the bond distance within the iodinemolecule linked to S is lengthened to 3.2 A (in gaseous I2 dp—I) == 2.66 A, while the van der Waals diameter of iodine is 4.2 A). Thusforms of the type RSI+(In)~ must be major contributors to the overallresonance structure.

References:

1. 0. Hassel. "Nobel Lecture" in Chemistry 1963-1970 (Nobel Lectures),Elsevier, Amsterdam (published 1972).

2. G.Y. Chao and J.D. McCullough, Acta Cryst. 13, 727-732 (1960).3. M. Bois-Enghien-Peteau, J. Meunier-Piret and M. van Meerssche,

J. Chim. Phys. Phys.-Chim. Biol. 65, 1221-1226 (1968).4. See J.W. Bransford and E.A. Meyers, Cryst. Struct. Comm. 1_>

(&1-1Q2 (1978) for the analogous Ph 3PS—O 2K—s p p h3 Structure.

5. F.H. Herbstein and W. Schwotzer, Angew. Chem. Intl. Ed. Engl. 2\_,219 (1982).

J

- 70 - 0

URANIUM IN APATITES.

A. Givan, I. Mayer and L. Ben-Dor

Department of Inorganic and Analytical Chemistry

Hebrew University, Jerusalem, Israel.

Uranium containing apatites were studied in order to examine the location of

uranium in the apatite l a t t i c e . This project was in i t i a ted in connection with the

possible exploitation of uranium from Negev Phosphates. Ca^PO )_0H (HA) and

Ca5(P0 ,C03)_(OH,F) (CA) were prepared in the presence of various amounts of ura:-'

nium.

The molar ra t io of U/Ca in the i n i t i a l solution of HA ranged from 0-10.5%.

EPMA analyses of the solid phases have shown a homogeneous distr ibution of U, P

and Ca up to U/Ca rat ios of 2.1% in the i n i t i a l solution. XRD patterns of apati te

containing these U/Ca rat ios were of single phase; above this ra t io uranium concen-

trated in a different phase.

Uranyl ions in the apati te matrix could be identified by the similari ty of

the i r emission spectra to U02 on other phosphate matrices. Assignment of Raman

and IR bands in the vibrational spectra of HA and HA containing 1% U was made on

the basis of functional groups.

Carbonate apati tes were prepared with i n i t i a l U/Ca ratios of 0, 0.02 and

0.08%. Activation analysis showed the uranium concentration of the compounds to

be 0.025 and 0.1%.XRD patterns of the compounds heated to 300C were similar to

what i s known for CA. At higher temperatures the decomposition of CA was f ac i l i -

ta ted by the uranyl ions. Emission spectra of CA showed that unlike in the case

of HA matrix, UCL emission in CA disappeared when heated to 100 C. This sug-

gests a different bonding of U0- in CA.

J

- 71 -

Low Temperature Synthesis of Chalcogenides

N. Yellin

Soreq Nuclear Research Center, Yavne, Israel

Chalcogenide material of very high purity(>99.9999%) are

essential for the production of optoelectronic devices

and nuclear detectors. The classical synthesis of such

materials is carried out at temperatures above the

melting point of the compounds, >1000°C, which involves

impurity (e.g. Si) diffusion from the quartz ampoule

walls into the material. In the case of mercury chalcopenides,

high pressures develop and occasional explosions of the

charpe ampoule are unavoidable.

In the present work synthesis of tellurides and selenides

of Hg, Cd, Pb and Sn at temperatures considerably below

the melting point of the compounds was studied. The

reaction went to completion within a few days. CdTe single

crystals grown from charges prepared by this method showed

very high resistivity and nuclear radiation detection,

indicating a very low residual impurity concentration

in the material.

J

- 11 -

ON THE DIFFERENCE IN THE OXYDATION OF 1,4,7 TRIACETATE-1,4,7 TRAZACYCLONANENICKEL(II), IN AQUEOUS SOLUTIONS, BY HYDROXYL RADICALS AND ELECTROCHEMICALLY.

Efrat Fuchs, Haim Cohen, Karl Wieghardt and Dan Meyerstein

Chemistry Departments, Ben Gurion University of the Negev,Nuclear Research Centre Negev, Beer-Sheva, Israel

and Ruhr University, Bochum F.D.R.

The oxidation of 1,4,7 triacetato 1,4,7 triazacyclonane nickel(II), Ni L, by

hydroxyl radicals and electrochemically was studied with the hope of obtaining

Ni L a new relatively stable strong oxidizing agent in aqueous solution. Stabi-

lization was expected in analogy with Ni EDTA, and as tertiary amino groups as

ligands are relatively stable towards oxidation and as tervalent tetraazamacrocyclic

nickel complexes are stabilized by ligation with anions.

The results indicate that oxidation by hydroxyl radicals indeed yields Ni L

however the latter reacts with oxygen k TTT = 30 M S , and seems to be aNi L+02

slugish oxidizing agent though it is a powerful oxidant, see below, and does not

oxidize, iodide and ferrocyanide. Electrochemical oxidation was not successful.

Although there is a one electron oxidation peak. (E « 1.05V vs. Ag(Ag C£), there is

a second oxidation process with a redox potential very close to the first one, that

produces a different oxidation product. This product has a different spectrum, and

is considerably less stable than the tervalent nickel produced by OH radicals oxida-

tion. Probably the electrochemical oxidation product is a Ni(IV) complex.

The results thus again point out that electrochemical redox processes often

differs from those caused by free radicals as electrodes might act as a several

electron redox reagent.

- 73 -

EFFECT OF METHYLATION ON THE PROPERTIESOF 1,4,8,11 TETRAAZACYCLOTETRADECANE NICKEL(I) IN AQUEOUS SOLUTIONS

H. Cohen, G. Ginzburg*, N. Jubran and D. Meyerstein

Chemistry Departments, Nuclear Research Centre Negevand Ben-Gurion University of the Negev, Beer-Sheva, Israel

The monovalent nickel complexes NiL (where L.. = 1,4,8,11 tetraazacyclo-

tetradecane, L2 = 5,7,7,12,14,14 hexamethyl 1,4,8,11 tetraazacyclotetradecane,

L, = 1,4,8,11 tetramethyl 1,4,8,11 tetraazacyclotetradecane and L. = 1,4,5,7,7,8,

11,12,14,14 decamethyl 1,4,8,11 tetraazacyclotetradecane) were prepared by electro-

chemical and pulse radiolytic technique (reduction by e~ or CO^). The redox2+ + aq /

potentials for the NiL /NiL are < -1.6V, -1.40V, -1.15V and -0.95V vs. SCE for

L = L-,L ,L and L. respectively. NiL1 and NiL9 are short lived in aqueous

solutions, tj < 1 min whereas t, (NiL_) ~ 30 min at pH 12 and tt (NiL.) > 100 hours

in neutral and alkaline solutions. The absorption spectra of the monovalent complexes

consist of a strong band in the near U.V., A nn.(e M~ cm" )375(4.5xlO );

380(3.6x10^); 353(3.1x10 ) and 335(3.6x10 ).The specific rates of reaction of NiL- with several oxidants are summarized in

the, table. (The results for NiL* are from Tait et al., Inorg. Chem. 1976, 15, 934.)

N20

°2Co(MH3)^

+

Ru(MK-)|+

J D

NiLx

3.2 x

2.5 x

6.2 x

6.4 x

107

109

io6

io8

3

1

1

3

NiL

.9 x

.6 x

.9 x

.8 x

2

io7

io9

io5

io8

8

1

4

+

.3 x

.6 x

8 x

.9 x

io2

109

105

107

<

4

1

3

NiL4

O.I

x 107

.7 x 104

x 1O7

The reactions with O_, Co(NH_)6+ and Ru(NH 3)* are suggested to involve single

electron transfer processes whereas those with N_O are believed to involve an3+

oxygen atom transfer yielding the respective tervalent nickel complexes. NiL. was

indeed observed as the product of the reaction.

The origin of the effect of methyl substitution on the properties of the mono-

valent nickel complexes with 1,4,8,11 tetraazacyclotetradecane is discussed.

*Dr. Gregory Ginzburg deceased August 5th, 1981.

CHEMICAL CATALYSIS

J

- 74 -

CATALYTIC HYDROGENATION AND TRANSFER HYDROGENATION REACTIONS IN

MULTI-PHASE SYSTEMS

Jochanan BlumDepartment of Organic Chemistry t The Hebrew Universityt Jerusalem, Israel

Several metal catalyzed hydrogen-transfer processes proved to be more efficient

and more selective under multi phase - rather than under homogeneous - conditions.

In the presence of a quaternary onium sal t , excess triphenylphosphine, an aromatic

solvent and aqueous sodium formate, RhCl(PPh-), promoted transfer reduction of

saturated ketones and nitro-compounds to give carbinols and amines, respectively.

Under similar conditions (90°C), PdCl2(PPh,)2 catalyzed both the selective transfer-

hydrogenation of a,g-unsaturated ketones and the hydrogenolysis of aryl bromides.

The lat ter process could be carried out under even milder conditions (<70°C) when

a mixture of benzyl alcohol and aqueous sodium hydroxide was used as hydrogen donor.

The mildest conditions for hydrogen transfer from aqueous sodium formate could

be achieved by utilizing 10% Pd/C, benzene and a mixture of 1:1 molar ratio of the

formate and water. At 30 C smooth reduction of aromatic nitro-compounds, olefins

and acetylens took place. The alkynes were init ial ly converted into the respective

cis-alkenes. Perchloro- and trichloro-methyl-compounds underwent selective hydro-

dehalogenation. Alkyl phenyl ethers cleaved to give phenol and alkanes, while

benzyl esters yielded toluene and the respective sodium carboxylate.

Aqueous RhCl, was shown to give dichloroethane-soluble RhCl," by addition of

methyltrioctylammonium chloride. The system proved to be a powerful hydrogenation

catalyst for alkenes, alkynes and arenes at room temperature and sub-atmospheric

pressure. The reduction of disubstituted aromatic compounds was shown to give

almost selectively ais-disubstituted cyclohexanes.

- 75 - 0

FORMATION AND REACTIVITY OF RUTHENIUM CARBOXYLATE COMPLEXES

Michel Rotem and Youval ShvoDepartment of Chemistry* Tel-Aviv University, Tel-Aviv 69978, Israel

Ruthenium carboxylates of the structural formula [Ru(C0)2(RCO2)]n are known onlyin the polymeric form ( R ^ . C H ^ E t . n - C ^ i g ) 1 . They are insoluble amorphous solids ob-tained by reacting Ru3(CO)i2 with carboxylic acids, which depolymerize upon reactingwith CO or other ligands (CH3CN,C5H5N, phosphines, a r s i n e s ) l i 2

c 0 [Ru(CO)3(RCO2)]

Ru3(C0)i2+RC02H —>- [Ru(CO)2RCO2]n

L [Ru(CO)2(RCO2)L]2

We have found that a h i therto unknown ruthenium benzoate complex is obtained byreacting Ru3(C0)i2 with benzoic ac id . Elemental analyses, l'r and nmr spectral data,as well as chemical transformations support a molecular formula [Ru(CO)2(PhCO2)]2. I tis a coordinatively unsaturated stable complex which has no analogy i n the rutheniumalphatic carboxylete ser ies. The results of a br ie f investigation d'f i t s chemistry isoutl ined below.

[Ru(CO)2(CH3CO2)]n

PhCO2H| lcH3CO2H| l

2[Ru(CO)2(PhCO2)]2[Me2CO] S P ^ [Ru(CO)2(PhCO2)]2 - * * [Ru(C0)3(PhC02)]

NMe3l1 — * • [Ru(CO)2(PhCO2)NMe3]2 << Ru3(C0)12+NMe3+PhC02H

In variance with the behavior of the alphatic complexes [Ru(CO)2(PhCO2]2 has notendency to polymerize. Our preliminary study of the cata ly t ic reac t i v i t y of th isclass of complexes in organic transformation led to the fol lowing resu l ts :a. In the presence of phosphines, [Ru(CO)2(PhCO2)]2 is an excellent hydrogenation cat-a lys t of ketones (1800 turnovers in 7.5 hours).b. The fol lowing ca ta ly t ic reaction was observed:

PhCsCPh+RCO2H R , ua( c ohfr , PhCH=C(OCOR)Ph + Ph2C=CHOCOR

140°cis + trans

The above reaction was carried out with benzoic and acetic acids: Ru3(C0)i2can be replaced with the corresponding carboxylate complexes. Of special interest arethe rearranged products - 1,1-diphenyl vinyl esters.

References: 1 . 6.R. Crooks, B.F.G. Johnson, J . Lewis and I.G. Will iams, J . Chem.Soc. A, (1969), 2761. 2. H. Schumann, J . Apitz and J . Pickardt, J . Orgmet.Chem. 128, (1977), 253.

- 76 - 0

FORMATION OF NEW C-C AND C-0 BONDS IN A HOMOGENEOUS CATALYZEDORGANOTIN COUPLING REACTION .

I. PRI-BAR - Nucluar Research Center-Negev, PO.Box 9001 Beer-Sheva.

J.K.STILLE - Department of Chemistry, Colorado State UniversityFort-Collins, Colorado 80523 USA.

The palladium catalyzed reaction of oC-halodetones with tributyl-allyltin to give allyl substituted oxiranes and their rearrangementproducts has been reported to take place under vigorous conditions(1)(100°C, 20 hours), because this reaction with tin reagents apearedto be promising method for th« generation of C-C bond a study of theutility and scope of this reaction was undertaken. A variety ofh^loketones or haloaldehydes were found to react with acetonyl- orallyltin reagents to give good yields of cyclic ethers. Oxiranes,oxentanes and tetrahydrofurans can be obtained under mild reactionconditions. The palladium catalyzed reaction is general for haloketonesor haloaldehydes but only tin reagents containing readily transferableorganic groups such as allyl and acetonyl react too give cyclic ethersin good yields (eq. 1).

0 X

Rl-C-(CH2)n.CHR2 +2 ) n .

0

n = o,l,2

R1* H, alkyl, phenyl

R2= H, alkyl

63°C

R3= alkyl,

\c y

(i)

RA

H"= allyl, acetonyl

The use of an optically active palladium catalyst containingmonophosphine ligands gave a small enanthiomeric excess (up toof chiral oxiranes from <* -haloketones. The mechanism of the reactionapears to involve addition of the organotin ligand to the carbonylforming a new C-C bond followed by palladium catalyzed cyclizationof the tin alkoxides to form the new C-0 bond .

(1) Kosugi,M.;1978, 795

Arai,H.; Yoshino,A.; Migita, T.,Chem. Lett.

- 77 - 0

PALLADIUM CATALYZED REDUCTIONS WITH GROUP IV A HYDRIDES

E. Keinan*, P.A. Gleize, N. GreenspoonDepartment of Organic Chemistry, The Weizmann Institute of Science,

Rehovot, Israel.

Trialkyl tin hydride was found to serve as an efficient hydride donorin very mild and chemoselective, palladium catalyzed reductions:

1) Conjugate reduction of activated olefins:

Bu3SnH

Pd(PPh3)4

2) Chemoselective reduction of allylic carbon-oxygen single bond:

OAc

CHO

OAc

Ph^^CN

Bu,SnH

Pd(PPh3)4

Both reactions are non-radical processes. The yield is significantlyimproved when a radical scavenger is introduced to inhibit undesired sidereactions. The chemo and regioselectivity is demonstrated by usefultransformations in the Withanolide series.

3) Polymethyl-hydrosiloxane (PMHS) was found to be even more

chemoselective than Bu^SnH:

Ph Cl

Bu3SnH

Pd(PPh-)

PMHS

0

Ph- H

- 78 -

\

CATALYTIC OXIDATIVE COUPLING OF ALCOHOLS WITH Ru3(C0)12

Y. Blum, Y. Shvo and M. KamDepartment of Chemistry, Tel Aviv University, 69978 Tel-Aviv, Israel

The cata ly t ic oxidative coupling of alcohols to esters with Ru3(C0)i2 i n t n e

presence of a hydrogen acceptor (A) has been recently descirbed by us 1 - 5 .Ru3(C0)12

2RCH20H + 2A — ^ RCO2CH2R + 2AH2

Kinetic studies reveal a two-step process; aldehyde was detected as an intermediate:

1. RCH2OH + A »- RCHO + AH2

2. RCHO + RCH2OH + A — * - RCO2CH2R + AH2

An al ternat ive ester forming step v iz . a Tishchenko reaction (eq.3) was ruled out \with the aid of several experiments.3. 2RCHO *- RCO2CH2R.

This is an interest ing point in view of a recent report which claims that t rans i t ionmetal complexes do catalyze the Tishchenko react ion.4

Detailed k inet ic studies reveal that both the aldehyde and ester forming steps,which were monitored separately, are dependent on alcohol concentration. However,neither of the above steps depends, on the acceptor concentration. Such a behaviorindicates that the H-transfer from metal to acceptor is faster than the dehydrogena-t ion of the alcohol substrates; the rate determining step must therefore be associatedwith the l a t t e r process.

I t was established that hydrogen addit ion to acceptors such as diphenylacetylene,chalcone and maleic anhydride is an i r revers ib le process. I t was also noted that withalcohols having low reduction potent ia ls , ester formation is incomplete, due to fastoxidation of alcohols to aldehydes which generates a f ina l alcohol deficiency (seeeq. l and 2) . To overcome this problem we have designed a reaction system employingan H-acceptor which acts reversibly (eq.4 and 5) .

Ru3(C0)124 . RCH2OH + cyclohexanone ^ ••- RCHO + cyclohexanol

Ru3(C0)12

5. RCHO + RCH2OH + cyclohexanone > - RCO2CH2R + cyclohexanolReaction 4 is an equil ibrium process catalyzed by Ru3(C0)12. I t controls, during reac-t i o n , a constant ra t io (RCHO)/(RCH2OH) thereby allowing reaction 5 to proceed quanti-t a t i ve l y . Since cyclohexanone has lower oxidation potential than most aldehydes, i twas used as a solvent. A peculiar feature of th is reaction is the requirement of acata ly t ic quantity of diphenylacetylene to prevent deposition of ruthenium mirror.

References1. Y. Blum, D. Reshef and Y. Shvo, Tetrahedron Let t . 22_(1981) 1541.2. Y. Shvo, Y. Blum and D. Reshef, J . Organomet. Chem. 226_ (1981) C21.3. Y. Shvo, Y. Blum and D. Reshef, J . Organomet. Chem., in press.4. T. I t o , H. Horino, Y. Koshi ro and A. Yamamoto, B u l l . Chem. S o c , Japan 55 (1982),

504.

J- 79 - 0

THE APPLICATION OF PALLADIUM(O)-DIISOCYANIDE MATRICES IN THE HETEROGENEOUS CATALYTIC

HYDROGENATION OF ALKENES AND ALKYNES

Avi Ef ra ty , I rene F e i n s t e i n - J a f f e , and Marcus Segal

Department of Organic Chemistry, The Weizmann I n s t i t u t e of Science, Rehovot, I s r a e l

The r eac t ions of 4 ,4 ' -d i i socyanobiphenyl with [Pd(n3-C3H5)(n5-C5H5)] and

[ P d C l ? ( l , 5 - c y c l o o c t a d i e n e ) ] 2 gave coordinat ion polymers of the types

[Pd(4,4*-diisocyanobiphenyl) ] (x=1.82±0.12) and [PdCl 2 (4 ,4 ' - d i i socyanob ipheny l ) ] n ,

r e s p e c t i v e l y . These matr ices were charac te r ized by means of elemental ana lyses ,

i n f r a r e d , dif fuse r e f l ec tance and X-ray photoelect ron spec t r a as well as by thermal

grav imet r ic and powder X-ray d i f f r a c t i o n . The heterogeneous c a t a l y t i c a c t i v i t y of

these mat r ices was probed by monitoring the hydrogenation of severa l alkenes

( e . g . , 1-hexene, t r ans -2-hexene , cyclohexene, cyclooctene, 1 ,5-cyclooctadiene,

1-octene and s tyrene) and alkynes ( e . g . , J-hexyne, phenylace ty lene , 2-octyne,

methylphenylacetylene, and diphenylace ty lene) . The r e s u l t s of t h i s study revealed

some extraordinarily fast catalytic reactions taking place in the presence of the

palladium(O) matrix under mild conditions. The catalytic hydrogenation of alkynes

revealed selectivity with respect to the semi-hydrogenation process as well as

stereoselectivity and stereospecificity with regard to cis hydrogenation.

J- 80 -

PALLADIUM CATALYSED ALLYLIC ALKYLATION WITH ALLENYL SFANNANE

Ehud Keinan* and Moshe Peretz

Department of Organic Chemistry, The Weizmann Institute of Science,Rehovot, Israel

Allenyl trialkyl stannane was found to serve as an efficient nucleophiletowards -n allyl palladium complexes (generated catalytically from allylicacetates and 5% Pd(PPho).). These allylic alkylations are taking place undermild neutral conditions and thus provide a novel chemoselective entry to1,5-ene-yne systems:

)Ac

CNPd(PPh3)4

The allenyl stanne nucleophile is a special case of e-y unsaturated organotinnucleophiles which react in a typical mode of allylic inversion:

X = CH2, 0

UNDSEAS (ISRAEL) LTD.38. King George St., Tel-Aviv

P. O. B. 2 3 0 1 1

irua

Phone: 299-091-2-3-4

T] ,38 'nvi i7nn aim2 3 0 1 1 .1 XI

Computer Aided Chemistry — the conceptthat is revolutionizing lab productivity

PERKINELMER

The microprocessor is at the first level of ComputerAided Chemistry This tiny chip now incorporatedinto almost every Perkm-Elmer instrument has re-sulted in a significant and dramatic increase in instru-ment productivity Improved control of instrumentparameters automatic testing and calibration ofinstrument functions and ease of setup and opera-tion are |ust a few of the benefits of microprocessor-based instrumentation

Model 3600 Data Stalon

Model983 dispersive IR with integral CRT and Model 1430IRSpectrophotometers

On the second level of Computer Aided Chemistryare the Perkm-Elmer Data Stations, with turnkey soft-ware for gas and liquid chromatography. for atomic,infrared, ultraviolet and fluorescence spectroscopy.and tor thermal ana elemental analysis Perkm-Elmeroffers the broadest line of proven ready-to-use soft-ware in the analytical field interactive processing ofinstrument data is only one aspect of this phase ofComputer Aided Chemistry Digital storage of instru-ment parameters and analytical methods, and auto-mation of repetitive procedures (from sampling to re-port generation) are a part of every Perkm-Elmer DataStation system Programmability in BASIC, and theability to operate as an intelligent work station within alarger laboratory computing system, further contrib-ute to making the Perkm-Elmer Data Station the mostpowerful small computer for the analytical laboratory

ICP/5500 — fastest, toughest, most flexible sequential ICP

LANDSEAS (ISRAEL) LTD.38. King George St., Tel-Aviv

P.O.B. 2 3 0 1 1o

Phone: 2 9 9 - 0 9 1 - 2 - 3 - 4

rj j s 'jmu -|?nn2 3 0 1 1 .7 n

SERIES 4 LC with LC-85 Detector/Autocontrol and LC Terminal

SERIES 4 LC: State-of-the-art versatilityand performanceBy Roy W.Yost

The SERIES 4 is a compact, high-performance qua-ternary solvent delivery system for HPLC, surprisinglymoderately priced. A positive-volume proportioningsystem delivers any combination of up to four sol-vents into a unique ultra-low dead-volume, high-speed pump which operates at flow rates from 0.1 to9.9 mL/min. High flow rate precision and accuracy,and instantaneous, in-pump solvent blending makethe SERIES 4 an ideal pumping system for both con-ventional and High-Speed/High-Resolution LC.

All input to the microprocessor-controlled pumpingunit is performed through a user-friendly keyboardlabelled in commonly-used chromatographic terms.The large video display unit shows a completemethod on a single screen page. During operation,the status of all key parameters is continuously dis-played and updated.

The standard SERIES 4 system can store up toten separate methods. The addition of the optionalChromatographics 2 Data System provides theSERIES 4 with full data-processing capability alongwith disk storage of data and results.

When methods are called into use — either man-ually or automatically sequenced — the SERIES 4immediately selects the required solvents andproper flow conditions. If the optional ISS-100Autosampler and full-contact column oven areinstalled, sample sequencing is also automated asis adjustment of column temperature.

Other high-performancePerkin-Elmer pumping systems

SERIES 3B microprocessor-controlled LC. TheSERIES 3B combines two performance-proven, dual-head 0-30 mL/min pumps with a maximum pressurerating of 6000 psi (41.4 MPa) with a controller offeringfive discrete full-curvature program segments, re-verse gradient profiles and two-way RS-232C com-puter communication capability.

SERIES 2/2. The SERIES 2/2 uses the same pumpsas the SERIES 3B to provide mixed-solvent, lineargradient or dual independent use, in a lower-costmodule. The 2/2 is the ideal instrument for mostanalyses not requiring the extra features of theSERIES 3B.

SERIES 2/1. The SERIES 2/1 is a single-pump ver-sion of the 2/2 which may be upgraded to dual-pumpuse as analytical requirements expand.

SERIES 1. The SERIES 1 is a single-pump systemwhich is recommended for dedicated isocraticanalyses.

PHYSICAL CHEMISTRY

- 81 - L

ANATOMY OF COMPLEX REACTION SYSTEMS.

KINETICS OF COMBUSTION REACTIONS FROM IGNITION DELAY TIMES

Assa Lifshitz

Department of Physical Chemistry, The Hebrew University, Jerusalem

One of the very useful methods of solving the kinetics and mechanism of

complex combustion systems is the measurement and modelling of the induction

period which precedes the ignition of a fuel in a shock tube. When a

mixture of a fuel and an oxidant is subjected to shock heating, it ignites,

following an induction period known as the ignition delay time. This delay

is the outcome of the exponential character of the overall reaction rate

resulting from various chain branching reactions and adiabatic temperature

rise during the course of the reaction. The delay time which is a readily

measurable quantity is a function of the initial temperature, pressure and

composition of the reaction mixture. The measurement of its dependence on

the reactant concentrations and temperature provides a very powerful tool

for modelling and thus understanding of the oxidation mechanism.

It is useful to summarize the dependence of the induction time in a simple

parametric relation that can later serve as a basis for computer modelling.

The general relation between the induction time and the concentrations is

very similar to the one which describes the rate of a reaction, that is,

where T is the induction time, C is the concentration of reactant i, and

B. is a parameter somewhat similar to an empirical reaction order. A can be

presented as

A = 10aexp(E/RT)

an expression very similar to a reciprocal rate constant. The parameters a,

E, and the g. are experimentally determined quantities, and they represent

a mean to summarize the experimental results in a quantitative manner.

After establishing an empirical relation as above and determining the

parameters, one can perform computer experiments under conditions similar

to the laboratory experiments and try for a given reaction scheme to

reproduce its parameters. One then arbitrarily varies the magnitude of

the various rate constants and examines their influence on the induction

period. The role the particular reaction in the overall mechanism can be

elucidated. Several examples are discussed.

- 82 -

QUASICLASSICAL TRAJECTORY STUDIES OF THE DYNAMICS OF THERMONEUTRAL ATOM-MOLECULE

REACTIONS.

Avigdor Persky, Michael Broida and Rachamim Rubin,

Department of Chemistry, Bar-Ilan Univers i ty , Ramat-Gan, I s r a e l

Q u a s i c l a s s i c a l t rajec tory s t u d i e s of the dynamics of s evera l nearly thermo-

neutra l atom-molecule react ions were carried out using semiempirical LEPS p o t e n t i a l

energy s u r f a c e s . The fo l lowing react ions and t h e i r i s o t o p i c analogs were i n v e s t i -

gated:

Cl+H2(v) »-HCl+H

O+H2(v) • OH-ffl

O+HCl(v) • 0H4C1

Cl+OH(v) • HC1+0.

From the trajectories, cross-sections, rate constants, kinetic isotope effects and

the energy distribution among reaction products were calculated and compared with

experimental results. The effects of the vibrational excitation of the reactants

and of the location of the potential energy barrier on the dynamics of the reac-

tions were also investigated.

- 83 -

PICOSECOND KINETICS BY INFRARED LINE BROADENING

Shmuel Weiss

Department of Chemistry, Ben Gurion University of the Negev, Beer Sheva

An exchange reaction in which a molecule alternates between two chemical envi-

ronments causes vibrational lines to broaden, coalesce and finally narrow as the rate

of exchange increases. The phenomenon, observable in the infrared (and Raman) is

completely analogous to that in NMR and ESR but is on the picosecond time scale.

Categories of reactions to which such line broadening may be applied as a means for

studying their kinetics include: charge transfer complexes formation and dissocia-

tion, hydrogen bond formation and dissociation, conformational transitions, proton

transfer, ionization and reassociation. Experimental results on a number of these

will be presented.

- 84 -

SOME APPLICATIONS OF A NEW MOIRE TECHNIQUE IN CHEMISTRY

0. Kafri

Nuclear Research Center-NegevPOB 9001 84190 Beer-Sheva Israel

Recently we have developed a novel optical method based on moire effect.

This technique, moire deflectometry^ ', is capable of measuring quantities

usually measured by interferometry, namely, refractive index and/or geometrical

changes. The accuracy of the method may reach that of interferometry. The

method is very simple and noncoherent, thus the requirement for mechanical

stability is imposed by the desired sensitivity of the measurement rather

than by the wavelength of the radiation, as in interferometry. We applied

this techniques to -some kinetic measurements. For example we have studied

the kinetics of the evaporation of cooling liquid in the atmosphere. We

saw that in water at temperatures above 50 C the evaporation rate is linearly

proportional to the vapor pressure. Thus, one is able to evaluate AH evaporation

in a very simple manner, from clausius - Clapeyron equation. At lower

temperatures the process rate does not obey the C.C. eq. and is slower

due to the non negligible humidity of atmosphere. In addition we'will

describe- measurements of refraction index as a function of time and

temperature measurements of flames by moire deflectometry.

References

1. 0. Kafri, Optics Letters £, 555 (1980).

2. 0. Kafri and A. Livnat Appl. Optics'20, 3098 (1981)

3. I. Glatt, A. Livnat and 0. Kafri - to be published.

- 85 -

NOVEL ASPECTS OF ELECTRONIC ENERGY TRANSFER IN SOLUTION

Shammai Speiser

Department of Chemistry, Technion - Israel Institute of Technology, Haifa 32000

Energy transfer processes play a major role in determining the dynamics of

excited molecular systems. Our present understanding of these processes

enables us to elucidate mechanisms of photochemical reactions and photophysical

properties of complex molecular systems.

In the gas phase vibration to vibration, vibration to rotation and vibration to

translation energy transfer processes are of major importance. In addition,

electronic to vibrational energy transfer, and electronic to electronic

excitation energy transfer are observed. Usually, energy transfer in the gas

phase is studied under collisionally dominated conditions. By contrast, in

condensed media and especially in fluid and solid solutions intramolecular

vibrational and rotational relaxation processes are extremely fast and

therefore only electronic energy transfer processes can be studied in these

media; in many cases long range collisionless interactions promote these

transfer processes.

In this lecture, while covering the major aspects of the theory of energy

transfer in solution, we will emphasize some recent developments in this

field: Temperature dependent energy transfer, intensity induced transfer,

involvement of high lying electronic states in energy transfer, determination

of molecular structure and conformational change in macro-molecules resulting

from intramolecular energy transfer, and utilization of energy transfer in

dye laser operation.

- 86 - 0

A Semi classical Adiabatic Theory of Resonances in 3D Reactive Scattering

by

Eli Pollak, Chemical Physics Department, Weizmann Institute of Science,

Rehovot, Israel 76100, and

Robert E. Wyatt, Institute for Theoretical Chemistry and Department of

Chemistry, University of Texas, Houston, Texas 78712

Recently i t has been shown that resonance energies in col linear

reactive scattering can be predicted accurately by a semi classical

quantization of resonant periodic orbits. The 3D analog of the orbit

is In principle a quasiperiodic rotating, bending vibrating trajectory

with quantised action along each degree of freeom. Since the time

scales of rotation bending and vibration are usually well separated

one can approximate this quasi-periodic orbit via an adiabatic reduction

scheme. For fixed angles one f i rs t solves the fast vibrational motion.

For each fixed angle one finds a resonant periodic orbi t . This orbit

then provides an effective potential for the rotation-bend Hamiltonian.

One then solves for the bending motion to obtain an effective Hamiltonian

for the 'sleepy' rotation. In this manner one finds that the 3D analog

of the resonant orbit is a resonating, bending, rotating 'rod1. Numerical

comparison of the semiclassical resonance energies found using this scheme

with exact (H+h^) and J 2 conserving (F+H2) quantal results shows good

agreement.

References

1. E. Pollak and M.S. Child, Chem.Phys. 60, 23 (1981).

- 87 - 0

KINETIC ENERGY RELEASE DISTRIBUTIONS

(KERDs) FOR GAS PHASE IONS; C4HgO+

by

C. Lifshitz and P. Berger

Department of Physical Chemistry, The Hebrew University

of Jerusalem, Jerusalem 91904, Israel

As part of an ongoing effort, we are studying highly excited polyatomic

cations and searching for the limits of statistical behaviour. The ions chosen

for this purpose are enol cations which undergo a rate-determining isomerization

followed by a fast bond cleavage.. This study is concentrating on the reactions

C.H_O* -»• CoH_0+ + CoH_. and C.Ho0* -> C_HcO

+ + CH_ of the enol ions of 2-butanoUe.

KERDs have been determined on a reverse geometry double focusing mass spectrometer

by computer control and accumulation of the data. The potential energy profiles

have been determined from appearance energy CAE) measurements. Bimodal distributions

will be discussed in the light of possible deviations from statistical behaviour.

Contributions from different product ion structure channels will be assessed.

0

GRAFTED MICROPOROUS REVERSE OSMOSIS (RO) MEMBRANES

Moshe G. Katz, Soreq Nuclear Research Centre, Israel

Theodore Wydeven, Jr., NASA - Ames Research Center, California.

Asymmetric cellulose acetate membranes were chosen as model

microporous membranes for the study of the effect of controlled

modification of the membrane surface by graft copolymerization

techniques, on their selective material transport properties.

The study is guided by a similar approach to that proposed

by Schultz and Asunmaa^ . In the present approach, possible

changes in the effective viscosity of the "ordered" water, as a

result of changes in the chemical structure of the membrane

material are taken into account. The objectives of this study

include investigation of the effect of the organizing inter-

actions between the membrane surface and the adjacent water

molecules on the state and properties of the "pore water".

The grafting process was carried out in a glow discharge

plasma. Preliminary results, obtained in the framework of

grafting experiments in N«, ^o^4 anc* ^ 4 P^asmas will be presented

REFERENCE:

1. R. D. Schultz and S. K. Asunmaa, Recent Progr. Surface Sci.

3, 291 (1970)

- 89 - 0

FORMATION OF SPATIAL DISSIPATIVE STRUCTURES IN A PHOTOCHEMICAL SYSTEM

M. Kagan, A. Levi and D. Avnir,Department of Organic Chemistry, The Hebrew University of Jerusalem

Jerusalem 91904, I s rae l

The poss ib i l i t y for the spa t i a l formation of d iss ipat ive s t ructures in achemical system has long been predicted by Prigogine . Temporal and spa t io -temporal d iss ipa t ive s t ructures are well known and have been studied intensivelye .g . the Belousov-Zhabotinskii o sc i l l a t i ng reac t ion 2 , and Winfree's waves.3

however un t i l recently no chemical reaction system was known to produce purelyspa t i a l s t ruc tu re s . Following a br ie f report of an observation by Mockel^ wehave studied the effects of UV photolysis on a shallow layer of solut ions con-taining a halogen radical source and a substra te which reacts with the halogenrad ica l s , or with molecular halogen, to yie ld a coloured product. We haveobserved t h a t , very short ly af ter the coloured product i s f i r s t formed there i sa breaking of the homogeneity of the solution in to spectacular three dimensionalshapes. These shapes are maintained and grow as long as the solution i s contin-uously i r r ad ia t ed ; i f the l igh t source i s removed they diffuse back in tohomogeneity. The role of the l i gh t , therefore i s not only in the formation ofthe halogen radical source but also to drive the reaction far enough fromequilibrium to allow for mul t i - s t ab i l i t i e s .

In identifying the necessary feed-back loop we have verified the predictionof Ross and Nitzan^, and completed the t r iad of chemical dissipative s tructures.We have found over 5Q reaction mixtures that show this effect and are presentlyinvestigating the generality of the phenomenon. Some examples are: KI/starch/water; tryptophan/chloralhydrate/water; 4-iodo-aniline/cyclohexane.

Finally, we draw attention to the significance of our study in the frameworkof chemical models to prebiotic evolutionary processes. The spontaneous gatheringof molecules out of a homogeneous environment, must have been the ear l ies t stagein the evolutionary time hierarchy. The phenomenon we describe i s a model systemfor such processes, the f i r s t one for a diffusion/chemical reaction network.

1. I . Prigogine and E. Nicolis, J . Chenu Phys. 46_, 3542 (1967].2. A.M. Zhabotinskii, Bioligika 9_, 306 (1964).3. A.T. Winfree, Sci. Amer. 82, June (1974).4. P. Mockel, Naturwiss., 64_, 224 (1D77).5. J . Ross, A. Nitzan and P. Ortoleva, J . Chem. Phys. 60_, 3134 (1974).

- 90 - 0

THE MINIMAL CHEMICAL OSCILLATOR

K. Bar-Eli

Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel

and

W. Geiseler

Technical University of Berl in, Berl in, West Germany.

Abstract

An open flow cerium-bromate-bromide system is investigated. The system

shows b is tab i l i ty under some constraints and monostability under others. The

mathematical properties of the system were investigated. I t was found that

near the cr i t ica l point, where the b is tabi l i ty disappears, the system starts

to oscillate since only one unstable steady state exists in that region.

The predictions regarding the range of b is tabi l i ty and the existence of osci l -

lations were borne out by experiment. The system turns out to be the simplest

known chemical osci l lator.

- 91 - 0

PERTURBATIONS OF BISTABLE CHEMICAL SYSTEM

K. Bar-Eli

Department of Chemistry, Tel-Aviv Universi ty, 69978 Tel Aviv, Israel

W. Geiseler

Technical University of Ber l i n , Be r l i n , West Germany.

Abstract

A bistable chemical system may be subjected to small perturbations, which

leave the system in its previous steady state and large ones, which cause

transitions from one state to the other. The small perturbations were investi-

gated for the possibility of using them as a tool to measure a particular rate

constant. Large perturbations were shown to cause transitions only if they

last long enough. Relationships between the perturbation intensity and length

are found. They seem to be of a similar nature as those developed by neuro-

physiologists in order to explain excitation of nerves by electrical pulses.

References

1. H.A. Blair, J. Gen. Physio!. T5_, 709 (1932)

ORDER AND DISORDER IN NONAQUEOUSSOLUTIONS OF ELECTROLYTES

N. Lotan

Biomedical and Chemical Engineering Departments, Technion, Haifa, Israel

We have previously reportedf'] on the conformational states of polymers inelectrolyte - containing nonaqueous solutions. Thus, using a variety ofphysico-chemical techniques, polymers bearing amide, ester, and phenolicmoieties have been investigated. We have concluded that, under appropriateconditions, high charge density ions - such as Li+- bind to the macromoleculesand, as a result of it, pseudopolyelectrolytes are formed. These effects arecancelled when water is added to the system. It was suggested that thesephenomena are promoted by specific interactions occurring between the electro-lyte and the solvent. The present report describes the testing and theconfirmation of this hypothesis.

Concentrated solutions (4-6 M) of LiCl in methanol exhibit rather unusualproperties: they are not miscible with ether f their viscosity is very high (upto 20 times the viscosity of methanol), and their nH nuclear magnetic resonancespectrum exhibits a quartet and a doublet for the -OH and the -CH3 groupsrespectively. When water (5-20%) is added to this solution, a separate singletpeak - assigned to the slowly exchanging HOD - is observe-i in the spectrum. Athigher water content (50%), the -OH peaks of water and methanol coalesce intoa singlet, and the same is the case for the - CHo doublet peak. Relatedresults were obtained for trifluorcethanol - containing solutions, with thedifference that, in these cases, lower concentrations of LiCl (0.1 - 0.2 M) arerequired.

The effects described are interpreted to indicate that the Cl~ anion is stronglysolvated by methanol,and even more so by trifluoroethanol. Extensivelystructured liquids are thus formed . As a result of it, "naked" Li+ cationsof high thermodynamic activity are obtained. This view is supported by theresults of electrolyte conductance measurements[2]on these solutions.

References

1. N. Lotan, J. Phys. Chem., 77, 242 (1973).

2. D.F. Evans, J.A. Nadas and M.A. Matesich, J. Phys. Chem., 75, 1708 (1971).

- 93 - 0

FRACTAL SURFACES: CHEMISTRY IN AN ENVIRONMENT OF A NON-INTEGER DIMENSION

GREATER THAN TWO

P. Pfeifer(a'15, D. Farin(b) and D. Avnir(b)

fai "F. Haber Research Center for Molecular Dynamics'- ' and the Department of

Organic Chemistry^ , The Hebrew University of Jerusalem, Jerusalem 91904

Israel.

Chemistry has been treated traditionally in a three-dimensional (bulk) or inan ideal two-dimensional (surface) environment. We suggest that in many cases amore natural way to analyse physical behaviour, is to do so in a dimensionalenvironment which has a non-integer value between 2 and 3. More specifically, themain point is that irregular surfaces have an effective dimension greater than two.This effective dimension, termed "fractal dimension", D, (after Mendelbrot(2)) isan intensive characterization, which gives a quantitative measure with predictivepower for a property which so far has been treated with great difficulty: theirregularity of surfaces. This problem is encountered in diverse fields such assurface chemistry, crystal growth> catalysis, host-guest interactions in proteins,enhanced Raman and fluorescence effects. We have developed three independentexperimental methods for determination of D: by analysis of the dependence ofsurface area on the cross sectional area of different molecules used for monolayercoverages(3*4)j by analysis of the dependence of the surface area measured with afixed yardstick-molecule, as a function of particle s ize^/ j and, if irregularityis due to porosity only, by analysis of pore-size distribution curves. * Existenceof a well defined value of D requires the surface to be self-similar upon magnifi-cations. Remarkably, we find that this seemingly strict condition is obeyed very ,,..often for a wide variety pf adsorbents, i . e . , fractal nature of surfaces is abundant.We have studied so far^ * ' silica gels, charcoals, graphites, clays, crushedglass, and found D values of the whole range. Thus, for graphite we obtain D=2.0and for a charcoal D=2.7.

(1) Current address: Fakultat fur Chemie, Universitat Bielfeld, D-4800,Bielefeld, FRG.

(2) B. Mandelbrot, "Fractals", Freeman, San Francisco, 1977.(3) D. Avnir and P. Pfeifer, preprint, 1982.(4) P. Pfeifer and D. Avnir, preprint, 1982.(5) D. Farin, D. Avnir and P. Pfeifer, preprint, 1982.

0

NON-EQUILIBRIUM CHEMISORPTION IN HETEROGENEOUS SYSTEMS

H. Birnholtz, Ch. Aharoni, A. Nir, and N. Lotan

Department of Chemical Engineering, Technion, Haifa, Israel.

Chemisorption of materials from the gas phase onto the surface of a solid

adsorbent is affected by temperature and pressure. Thus, for example, the

exothermic character of the process predicts that equilibrium isobars will be

monotonously descending functions of temperature. Such an appearance was in-

deed observed experimentally in a variety of systems, and a schematic represen-

tation of it is shown in Fig.l (curve A). In some instances, however, one notes

a rather peculiar behaviour, namely isobars show a minimum, a maximum,or

both (Fig.l, curve B).

Amountof materialadsorbed

Figure 1.Schematic repre-sentation of chemisorptionisobars.

Temperature

In the course of our studies on chemisorption we have developed a model

which takes into consideration both the equilibrium states and the dynamic

aspects of the process, while assuming that: a) the adsorbing surface is

heterogeneous and made up of two types of sites; b) material from the gas phase

can reach the surface only at sites of one type, while the other sites are

supplied merely from the former ones, and by a surface diffusion process. This

model accurately predicts the complex type isobars mentioned above (Fig.l,

curve B), and reveals the fact that they actually represent transient states

rather than equilibrium ones. The latter (Fig.l, curve A) are reached

after extended periods of time, and are also accounted for by our model.

- 95 -

Magnetic Circular Dichroism studies of DAB CD

Aharon Gedanken

Department of Chemistry, Bar-Ilan University,

Famat-Gan 52100, Israel

Absorption and multiphoton ionization measurements of DABCO

(1,4 diazabicyclo [2 ,2,2]octane) were able to identify two electronic

transitions. The origin of the f i rs t one is observed at 279.37 nm and

is assigned as the n •*• 3s Rydberg transition while the second transi-

tion is located at 251.1 nm and is assigned as the n •*• 3p transition.

Differences exist in the assignment of n -»• 3p transition. Halpern et a l .2 1 1

and Hamada et al . prefer the A' •* A" (n -»• 3p2) transition, while

Parker and Avouris concluded that i t should be assigned as the

\ - % • {„ - 39^).

We have carried out MCD measurements of DABOO in the gas phase and

obtain for each member of the vibration.il progression of the n -*• 3p a

derivative line-shape A term. This observation immediately requires the

conclusion that the excited state involved in this transition is degenerate.

The transition is therefore unambiguously assigned as A' -*• E1 (n -> 3p ) .1 1 xv

The magnetic moment of the excited E1 was calculated to be -0.173+0.02

where 3 is the Bohr magneton.

References

1. A.M. Halpern, J.L. Poebler and K. Weiss, J. Chem. Phys. 49_, 1348 (1968)

2. Y. Hamada, A.Y. Hirakawa and M. Isuboi, J. Mol. Spect. jl7_, 440 (1973)

3. D.H. Parker and Ph. Avouris, J . Chem. Phys. 2i» 1 2 4 1 (1979)

- 96 - 0

MOLECULAR DYNAMICS OF POLYMERS IN CHAOTROPIC MEDIA

N. LotanBiomedical and Chemical Engineering Departments, Technion, Haifa, Israel

The chain conformation and intramolecular mobility of nonionizable poly-amides, in water and in calcium chloride-containing aqueous solutions, have beenstudied.

The polymers considered were of two classes: chiral (polyamino acids) andachiral (poly-N-vinylpyrrolidone), and their hydrodynamic and nuclear magneticresonance (NMR) properties were investigated. The conformation and conformatio-nal transitions of polyamino acids were also established by circular dichroismmeasurements. For comparison, corresponding NMR properties of low molecularweight model compounds were also determined.

A typical effect observed in our polymer-containing systems is presentodin Fig.l. The main feature revealed is the extreme broadening of the NMR peaks

HOD

Figure 1. NMR spectra of

poly-N-vinylpyrrolidone:

(A) - in DO

(B) - in 3.9 M CaCl in D 0

occurring upon increasing the salt concentration. No such feature was noted withlow molecular weight model compounds.

The ensemble of the results obtained are interpreted to indicate that, inwater, the polymers assume a disordered and flexible conformation, of highmobility. Upon increasing the salt concentration the overall disordered confor-mation of the polymer chains is preserved, yet the intramolecular mobility andchain flexibility are progressively lost. It is hereby suggested that theseeffects are caused by a multidentate binding of Ca ions at the amide groups,leading to intramolecular bridging of the polymer chains.

- 97 -

''Local Field Enhancement in Aggregated Dielectric Films"

Zvi Kotler and Abraham NitzanDepartment of Chemistry, Tel-Aviv University

Tel Aviv 69978, Israel

Results of calculations aimed at estimating enhancement ratios for averaged

electromagnetic f ie ld intensities in island films are presented. The enhancement

ratio for the inter^island environment is calculated using Nitzan-Bergman enhance-2

ment ratio for two component materials - and is found to be of the order of MO

for Ag particles.

The f i lm is modeled by a distribution of ellipsoids of revolution lytng on a

substrate with their optic axis perpendicular to i t .

The dipole approximation is employed and care is being taken of image effects,

size effects and radiation damping.

The magnitude of the enhancement and peaks position are found to be dependent

on the part icles' shape, size and density, and also on the substrate chosen.

- 98 -

TIME RESOLVED PHOTOIONIZATION MASS SPECTROMETRY

by

C. Lifshitz, M. Goldenberg and Y. Malinovich

Department of Physical Chemistry, The Hebrew University

of Jerusalem, Jerusalem 91904, Israel

A photoionization mass spectrometer operating in a time resolved manner,

from the microsecond to the millisecond range, has been constructed. The central

part of the instrument is a Cylindrical Ion Trap (C1T) of the type used previously

in conjunction with electron impact experiments. A Hinteregger VUV light source

is operated in a pulsed mode and the photoions produced are trapped in the CIT.

They are ejected into a quadrupole mass filter by a drawout pulse, following a

variable delay time, and counted only during the ejection pulse.

The instrument is being employed for measurements, of time resolved photo-

ionization efficiency curves and breakdown graphs. Reactions studied include

CgHg -*• CM, + C2H_ in cyclo-octatetraene, which demonstrates a very slowly

rising rate-energy dependence as function of the excess energy above threshold.

It is estimated that dissociations, having rate coefficients kCE) « 1 sec~ , can

be detected.

- 99 -

FLUORESCENCE STUDIES OF RUTHENIUM TRIS-BIPYRIDINE AND OF EUROPIUM TRIS-BENZOYLACETONATE ADSORBED ON POROUS SUPPORTS*

N. Manor(aj, R. Reisfeld^** and D. Avnir^(a)The Departments of Inorganic and Analytical Chemistry^ J and Organic

Chemistry^" , The Hebrew University of Jerusalem, Jerusalem 91904, Israel.

As part of our study of surface effects on photophysics and photochemistryof adsorbed molecules we have investigated the fluorescence of ruthenium tris-bipyridine (RTBD) and of europium tris-benzoylacetonate (ETBA). Two types oftransparent surface-hydroxylated porous adsorbents were used: (a) Compresseddiscs of fumed silica-gel. These were obtained by applying a pressure of 10tons/cm^ on the 14 ym particles of the silica; (b) Corning Vycor porous glass(7930), of surface area 200 m2/gr (by the N 2 BET method). The pore diameterrange, 40-7Q&, is sufficiently large for the penetration of the organometallicdyes.

We have found that high luminosities are obtained from the adsorbent plates.E.g., for ETBA we have found a remarkable enhancement in luminosity as comparedto solution. Longer fluorescence life times were observed for both adsorbedRTBD and adsorbed ETBA as compared to solution. These phenomena probably resultfrom: a) the ability to achieve high concentrations due to the large surfacearea.of the adsorbents; b) strong adsorbent-adsorbate interactions whichdiminish adsorbate intermolecular quenching processes; and c) in the absence ofsolvents, fluorescence quenching by high stretching frequencies is avoided.

We draw special attention to the significance of our findings, especiallywith RTBD, in the context of luminescent solar collectors. This aspect of ourwork is discussed elsewhere.

In a typical experiment, a 1.3 mm thick 0*00 mg) Vycor plate was loaded withRTBD to a concentration of 4*10~2 moles of dye per liter of glass. Life timemeasurements (emission: 620 ran) on the strongly luminescent plate revealed anexponential decay rate with a mean life time of 0.45 ysec (0,37 ysec in solution).In contradistinction to RTBD, the decay rate of ETBA is non-exponential. Thisdifference is attributed to island formation of ETBA upon adsorption, whereasRTBD probably forms an evenly spread layer. Further experiments are in progress.

* Partially supported by the Israel Ministry of Energy and U.S. DOE contractNo. 80-1-09, and by the E.D. Bergmann Foundation.

** Enrique Berman Professor of Solar Energy.

- 100 -

(BSA) innni *ro ' n y *tv

nmn*ai

.jmayn

ntna

Din D11D2

mna , ' 3 ax . nms nain Nin np'ui'p Vy yi'nn

TXIJ 'HB»NT Dp"73mp ~>D liHuni .stopped flow T e a m

23 s" 1 *7B>

nx

m^n m 'inN ;Tnn

ni' iun QN p a i v ' z n n'Vnm ,'7n"7 pm xm 'JIWKIH op^smpn 'D

in nnpiyn ni 'ymiDonun -»ne» 'D niNxinn hv nT'*73Nn nxm p - i n o

'yiap T\H 'U3'p IQIKI ^IP1? IK/DN-'N ,13*7 .n inny HTXP^'T *7» imyn nunni

.nn'nnn 'yiap A VD IIN D'V'^nn O"ion DHB .n'XDp^in 'am HN PTI IN N*7N

i n n 'D aisvn1? i n ' i n'n »pH n n'^y oy m^iy n i ' i i 'nnn VDW uran

naiiv N'n HT nayn VB* i m n IN .Tma^Na 7.5 pH na'a^i "7nn T^nn ,N ^ B

aiw laiiNxn "pH nx'Dp" m j i ' p j a , I T M O .pH a ni»n»nnn niVn "7B» u n 'mno

'3 11*7 nNia ID1? .Dp^ampn nvy*1? a'on'unn nVNn m i ' D'T»no IH .n'^Dp^T 'am

nayn1? •JIDP'TJ'N N^N minn ia-»N p a n ' ^ ' a n i ,N t B laynn IIN D'rnn nVn D'3iiT

.•»ynian-Tn i9iKa u n nnann m n^in1? i n ' ! own nVNi?1; Tm'na Tiam JJN

- 101 -

PICOSECOND TIME RESOLVED ELECTRONIC ENERGY TRANSFER

IN MIXED CRYSTALS AND FLUID SOLUTIONS

D. Rojansky and D. Huppert

Chemistry Department, Tel-Aviv Univers i ty , 69978 Ramat-Aviv, Israel

Picosecond time resolved fluorescence spectroscopy measurements were used

to invest igate e lect ron ic energy t ransfer (EET) in the fo l lowing systems:

1) tetracene doped anthracene crystals

2) anthracene and tetracene doped naphthalene crystals

3) methanolic solut ions o f rhodamine 6G(R6G),and f luorescine disodium sa l t

4) methanolic solut ions of f luorescine disodium sa l t and DODCI.

In the f l u i d solut ions the donor (Fluor. Dis. sa l t ) concentration i s in excess

with respect to the acceptor concentration (DODCI, R6G).

I t was found that the host luminescence decay law:

n(t) = n°(t)exp(- | ^2_ C f t / I T - o^Sx*^3 '2 (Dto)3/4 ^ )

fits well with the experimental data. This expression was proposed by

Gosele and Golubov and Konobeev for combined exciton diffusion and long-

range transfer.

(Postdeadline) - 101a - P

RESONANCE RAMAN SCATTERING AND FLUORESCENCE

OF MOLECULES ADSORBED ON SILVER-ISLAND FILMS

D.A. Wei tz a , S. Garo f f 3 , J . I . Gers te in b and A. Ni tzan c

a Exxon Research and Engineering Co . , P.O. Box 45 , L inden, NJ 07036

b Department o f Physics, C i t y College o f the C i t y Un ive rs i t y o f New York, New York,NY 10031

c Department o f Chemistry, Te l -Av iv Un ive rs i t y 69978 Ramat A v i v , Israe l

andDepartment o f Chemistry, Northwestern U n i v e r s i t y , Evanston, IL 60201

The enhancement o f regu lar raman sca t te r ing (RS), resonance raman

sca t te r ing (RRS) and f luorescence from molecules adsorbed on i den t i ca l wel l

character ized S i l v e r - I s l a n d f i lms are repor ted . A hierarchy o f enhancement

r a t i o s i s found w i t h t yp i ca l values of 10 fo r RS, l o 3 fo r RRs and 0.1-3 fo r

f luorescence, the l a t t e r depe-nding on the quantum y i e l d associated w i th the

f luorescence o f the f ree molecule. These experimental r e s u l t s are discusssed

w i t h i n theframework o f the electromagnetic theory o f SE?S general ized to t r e a t

molecular resonance phenomena. The r e l a t i v e i n t e n s i t i e s associated w i t h the

observed RS, RRS and f luorescence processes lead to a determinat ion of the r o l e

played by the surface plasmon resonances and by the surface induced damping o f the

molecular e x c i t a t i o n , in these various types of l i g h t sca t te r ing processes. The

observed hierarchy o f enhancements i s shown to have important spectroscopic

consequences.

A new age inliquid scintillationmeasurementsystems

TheTRI-CARB460Cby Packard

Packard

The World LeaderIn Liquid ScintillationCounting

Linear RecordersHigh quality and reliable performance

are critical to most applications. That is whyLinear recorders have been selected by morethan 43.000 laboratories, universities, researchcenters, medical institutions and private indus-tries throughout the world.

Linear has been an innovative leader inanalog strip chart recorders since 1971. Our penJrive system was patented in 1978. Known asLinears "Pulse Modulated Servo;" this systemprovides accurate, stable recording with lowpower consumption (U.S. Patent No. 4,146.828).

Reduced system complexity and digitaltechnology are combined with a simple mechan-ical approach to make Linear recorders simpleto operate, easy to understand and maintain.They are designed to give you dependableresults, chart after chart.

Linear recorders fit a wide variety of appli-cations, accurately and economically. Our prices,which include many extra features, are still lessthan the base price of many competitive models

Linear InstrumentsCorporation

Corporate Headquarters:17282 Eastman AvenueIrvine, California 92714

Represented by ELDAN ELECTRONIC INSTRUMENT CO. LTD.16 OHOLIAV STREET • JERUSALEM 94467 ISRAELP.OB. 1S7O. JERUSALEM 91O1S

JASCO INTERNATIONAL CO., LTD.2-4-21, SENNINCHO. HACHIOJI-CITY, TOKYO 193. JAPAN

The Model UVIDEC-610 is newly designed UV/VIS spectrophoto- values with the built-in CRT display. This feature allows not only easemeter which enables the operator visual communication for all the of operation for inexperienced operators but also more sophisticatedconditions and the results of measurement for both of spectrum and work for the experienced operators.

continuousgas measurementby Infrared

mf'cedonc.vze'S fc *he r^eosurerrer-T cj *'J 00:65 ~he^e solid ^o*e oerector cnoiyzers;ffer fcs' -esporse .C\A roc-e. high occuccv,ow rncptencrce oro o modercTe price

\r< Mode: ?C; --iPQie go:, onoiyzerIP Mode. 7C2 orcyze; two gcses sIP Modei /DC mu't: pet sonnpie gos conditone'

INFRARED INDUSTRIES, INC.Western Division, Instrumentation GroupP O Box 989. Santa Barbara, CA 93102(805)684-4181

Represented by\ Eldan

ELOAIM ELECTRONIC INSTRUMENT CO. LTD.

16 OHOUAV STREET • JERUSALEM 94467 SBAEt.P.OB. 137O. JERUSALEM 91O1S

TEA AnalyzerFor Nitrosamine Analysis

sfc Thermollz ElectronCOSPOfliTION

Analytical InstrumentsRepresented by

0 0

I Eldan ECDAIM ELECTRONIC INSTRUMENT CO. LTD.16 OHOLIAV STREET • JERUSALEM 94467

P.OB. 127O. JERUSALEM 91O1S

ELECTROCHEMISTRY

- 102 -

PHOTOELECTROCHEMICAL SOLAR CELLS

David Cahen, the Weizmann Institute of Science, Rehovot

The photovoltaic effect at the semiconductor/liquid electrolyte junction can

be used to construct a photoelectrochemical cell (PEC). Such a cell has several

attractive features, such as the possibility of using thin film polycrystalline

semiconductors with minimal conversion losses. Work at the Weizmann Institute

has been concerned with producing such cells with acceptable output stabilities

and performances, and thus with identifying factors that affect these characteris-

tics. Several systems are under investigation, and of these the Cd-chalcogenide

(CdSe, CdTe)/polysulfide is the most advanced. Solid state chemical considerations

led to our study of ternary chalcogenide/polysulfide PEC's. These latter systems

show superior output stability and, when single crystal semiconductors are used,

performances comparable to those of the former ones. For all systems proper

surface treatments are necessary to achieve optimization. This leads to another

aspect of this kind of work, viz, reaching an understanding of the semiconductor

surface chemistry, using electrochemical methodologies. Achievement of this goal

clearly has a bearing not only on solar cells, but on many other areas of semi-

conductor technology.

- 103 -

DOUBLE LAYER EFFECTS IN SQUARE WAVE POLAROGRAPHY

Ch. Yarnitzky

Department of Chemistry

Technion - Israel Institute of Technology, Haifa, Israel

Square wave polarography is useful in basic electrochemical

research and trace analysis. In either case, the charging current

must be taken into account when the polarograms are evaluated. It is

well known that as the potential changes the fast charging current

decreases rapidly, (assuming that the double layer-cell resistance

time constant is much shorter than the square wave period) to the

small charging current accompanying the growth of the mercury drop.

However, the periodic change of the potential causes some change in

the surface tension of the drop, which depends on the direct potential

and the amplitude of the square wave. Mechanical vibrations of the

drop, occurring at a certain drop mass, generate another type of

charging current which appears as a current peak. This peak must be

identified and distinguished from the peaks recorded when

electroactive species are present. In addition, the small charging

current distorts the base-line and limits the sensitivity of the

method. Background compensation has been achieved by adopting the

alternate drop method or a computerized system. The first method

doubles the electronic noise and recording time, and the second is too

complicated for use in conjunction with laboratory instruments. We

have proposed integrating the fast changing current and using this

charge as a source for the compensating current.

The mathematical relations between the vibrations and the drop

parameters, as well as the theoretical treatment of the new

compensating technique will be discussed.

- 104 -

DELAYED OPEN-CIRCUIT VOLTAMMETRY

Dov Talmor and Emil ia Kirowa-EisnerI n s t i t u t e of Chemist ry , Tel-Aviv Un ive r s i t y , Tel Aviv G997ti

A new t e c h n i q u e , DELAYED OPEN-CIRCUIT VOLTAMMET.RY (DOV) i s

p roposed for t h e q u a n t i t a t i v e t r e a t m e n t of c h e m i c a l r e a c t i o n s

e _ kf

kufollowing charge transfer*. 0

The technique is related to a previous one used by us, i.e., the

REVERSE PULSE POLAROGRAPHY method (RPP).

The principle of DOV is as follows: The electrode is

potent iosta ted for a time t g at a potential at which tiie

electroactive material, 0; initially present in the solution is

reduced at the diffusion limited rate. Products (P) and intermediates

(I) are accumulated in the diffusion layer. The electrode is then

disconnected and left under open circuit conditions for a time t

While at open circuit, the chemical reaction in the diffusion layer

proceeds simultaneously with diffusion of all the species. The

progress of the chemical reaction is then followed by applying a

potential pulse in a region in which the intermediates and the

products are oxidised. The pulse potential is changed and the

sequence is repeated changing the potential of the pulbe. In the case

in which I and P exhibit separate oxidation waves, the obtained DOV

contains direct information on the relative concentration of the

species present in the immediate vicinity of the electrode as a

function of time. Working curves for the determination of the rate

constants are calculated by digital simulation, taster reactions can

be studied with DOV compared to RPP.

- 105 - 0

ELECTRO-CATALYTIC REDUCTION OF O 2 BY METALLO-PORPHYRIN MONOMERS AND DIMERS

J.Y. Becker, D. Dolphin, J.B. Paine III and S.F.B. Pickett

Departments of Chemistry, University of British Columbia, Vancouver, B.C., Canada,

and Ben-Gurion University, Beer Sheva, Israel.

The electrolysis of 0 2 reduction has been studied using the rotating ring-disk method-

A pyrolytic graphite disc was coated with varying amounts of cobalt(II) octaethyl-

porphyrin, cobalt(II) mesoporphyrin II dimethyl ester and polymethylene-bridged

doubly-linked cofacial dicobalt porphyrin dimers. Electrocatalytic reduction of

O_-saturated 0.5M aqueous trifluoroacetic acid showed that at high adsorbed concen-

trations monomeric porphyrins may be efficient catalysts for electroreduction of 0

to H20 although some H2O2 is detected at the Pt ring electrode.

- 106 - 0

LOW-RATE Li/S ORGANIC CELL

H. Yamin and E. PeledDepartment of Chemistry, Tel-Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel

The Li/S couple has one of the highest theoretical gravimetric and volumetricenergy densities.

This paper describes the development and electrochemistry of low-rate laboratory

Prototype button c e l l . As a test vehicle for the research, we used a laboratory pro-

totype stainless steel button ce l l . The cathodic-current collector was teflon bond-

ed carbon electrode supported on Ni Exmet. I t was charged by elemental sulfur or

polysulfide. Celegard porous polypropylene, or glass paper, were used as separators.

Sealing of cover to can was accomplished with the use of a combination of organic

elastomer and cement (to avoid crimping). This sealing was leak proof since cells

which were stored for three weeks at 60°C lost less than 1 mg of weight.

Two types of cells were bu i l t : Type A - 900 wh/1 (or 1130 wh/kg) ce l l . Al l en-

ergy density values were calculated on the basis of a l l cell components, excluding

the case. Electrode area was 2.5 cm2 and ce l l 's internal thickness was 2.1 mm for

type A and 2.5 mm for type B. Net volume of cells was 0.6 and 0.72 ml for type A

and B, respectively.

A very important feature of Li cells is the low self-discharge. Several d i f fer-

ent self-discharge and Li corrosion tests have been made. Some of them are present-

ed here. Capacity loss at 60°C, both under OCV or during discharge, was found to be

2-5% per month depending on the electrolyte composition. From these and other tests

i t is estimated that the shelf l i f e of Li/S cells at room tesuperature wi l l be ten

years or more.

Sulfur ut i l izat ion in type A cel ls, at room temperature, exceeds 95%, and thecel l 's energy density is 900 wh/1 (or 730 wh/kg). Type B cells at 60°C delivered 86%of i ts nominal capacity, i .e . 950 wh/kg (or 1200 wh/1). Discharge curves are f l a t(above 2.0V). Cells were successfully discharged at -20 to +70°C. Nominal presentrates for continuous discharge are: 5, 10-15 and 20-30 yA cm"2 for -20, 25 and 60°Crespectively. Cells can deliver short current pulses up to 0.1 mA cm"2.

- 107 - 0

The behavior of the Li/SOC^ system at elevated temperatures

M. Babai, J.BinethLithium Battery PlantTadiran, Israel Electronics Industries. Ltd.P.O.Box 75, Rehovot, Israel 76100

One of the promising ambient primary lithium systems selected for commercializationin recent years utilizes the lithium-thionyl chloride couple. This system ischaracterized by its high energy density (gravimetric and volumetric), goodoperating capabilities over a wide temperature range, reasonably high currentdelivering capabilities and low self-discharge rates.

In this system, thionyl chloride serves the dual role of an electrolyte carrierfor the solute ions as well as a cathodic depolarizer. Contrary to most otherambient lithium systems, where organic solvents serve as the electrolyte, theabsence of organics in the Li/S0Cl2 system is reflected by an enhancement ofboth the chemical and the electrochemical stabilities of the Li/SoCl^ system.There is evident improved stability in storage and discharge capabilities attemperatures as high as 150^C, even though the boiling point of the thionylchloride electrolyte is only about 0

This report summarizes the electrical performance of D-size cylindrical cellswithnominal capacities of 10 AH at temperatures up to 150°C. It is shown thatabove 100°C, decomposition of thionyl chloride to chlorine, sulfur dioxide andsulfur monochloride takes place. The decomposition products increase the ratecapability of the cells and change the morphology of the passivation layer onthe lithium anode. The scanning electron microscope (SEM) photographs of the filmgrown on the anode, following storage for 7 days at temperatures up to 185^C,are given.

The results confirm a duplex film mechanism, suggesting that the passivationlayer on the lithium anode corsists of a thin, dense insulating LiCl layerunderlaying a much thicker layer of porous, non-insulating LiCl film.The thin, dense film determines the distinctive electrochemical stability of theLi/SOCl2 system.

- 108 -

ENSEMBLE OF MICROKLLCTKODES: DIGITAL SIMULATION BY THE TWO-DIMENSIONAL EXPANDING GRID METHOD APPLIED TO CYCLIC VOLTAMMETRY

Hannah K e l l e r , Emilia Kirowa-Eisner and El ieze r Gi lead iI n s t i t u t e of Chemistry, Tel-Aviv Un ive r s i t y , Tel-Aviv 69978

In an ensemble of microelectrodes, the surface is composed of

active si tes and inactive areas. Diffusion towards the active site

has a radial component in addition to the perpendicular component,

resulting in a thinner diffusion layer than calculated for semi-

infinite linear diffusion. Hence, faster electrode reactions can be

studied on ensembles of microelectrodes than on large electrodes (1).

Linear potential sweep is widely used with stationary solid

electrodes for the elucidation of the mechanism of electrode

reactions. The use of ensemble of microelectrodes extends the ran-je

of cyclic voltammetry to the study of faster electrode reactions.

The mathematical treatement is based on the digital simulation

method proposed by Feldberg (one-dimensional expanding grid) (2). for

the case of microelectrodes, this method is further developed here

for a two-dimensional expanding grid. Compared with a uniform grid,

a considerable saving in computation-time is acheived.

References

1. H. Heller, E. Kirowa-Eisner and E. Gileadi, J. Electroanal.Chem., in press.

2. S.W. Feldberg, J. Electroanal Chem. 127 (1981) 1.

- 109 -

Time Resolved Photocurrent Photopotential and Photoluminescence Studyof n Type CdS and CdSe Photoelectrodes

2. Harziona, N. Croitoru , D. Hupperta and S. Gottesfelda

aDepartment of Chemistry, University of Tel-Aviv, IsraelDepartment of Electronics, University of Tel-Aviv, Israel

The importance of kinetic parameters in the determination of the efficiency andstability of semiconductor photoelectrodes has been stressed by many authors. Transienttechniques have served as an important tool for the evaluation of kinetic parametersin both electrochemical and solid state solar cells. The use of such techniques inphotoelectrochemical cells has been introduced recently. Short light pulses aimed atthe semiconductor surface are used in such techniques to perturb the photoelectro-chemical system.

We have previously studied the photocurrent transients in a CdSe/S~, S° cell,generated by short (nS) light pulses (1). The detailed analysis of the photocurrenttransients decay time (1) revealed that it was RC controlled, with the value of Rreflecting the extent of trapping in the damaged surface layer. It was found thatphotocurrent decay is sensitive to the state of the photoelectrode (CdSe crystal)surface.: Chemical etching enhanced the amplitude and reduced the decay time of thetransients, and increased the photocharge obtained (per flash).

In subsequent measurements of electrical transient signals, the open circuit photo-potential transients revealed a decay rate which is proportional to the value of thedark current measured for the same semiconductor electrolyte interface under a smallapplied bias. This result ("RinfC controlled" decay) means that under open circuitconditions Rj n^ *

s determined by the rate of the majority carriers transport acrossthe barrier to the outer surface, where the recombination takes place. Analysis ofthe apparent R^nt.C time constants and their comparison to measured dark currents,reveals that the kinetics of charge separation ;cart be.followed. Incomplete charge-separation is.encountered in damaged surfaces.

Finally, photoluminescence decay and quantum yield studies, following pS laserpulses, show a parallel bahaviour following the same surface treatments: The lumines-cense decay time for the etched crystals is 10 times longer than in mechanicallypolished crystals, and the quantum yields increase by more than an order of magnitude.

Of special interest are results on sub-bandgap luminescence (SBGL) processes,which proceed at high quantum efficiencies in some of the samples examined. TheSBGL processes reflect very fast recombination modes, and may also provide informationon the involvement of mid-gap states in the photocharge transfer process.

The combination of transient photocurrent, potential and luminescence measurementsthus seems to be a promising approach to the identification and monitoring of thecomponent processes of the photoelectrochemical reaction.

Reference

1) Z. Harzion, N. Croitoru and S. Gottesfeld, J . Electrochem. Soc., 128, 551 (1981).

- 110 -

ELLIPSOhETRIC AND IMPEDANCE MEASUREMENTS OF OXIDE FILMS

GROWN ON RUTHENIUM ELECTRODES

J. Rishpon, I. Reshef & S. Gottesfeld

Department of Chemistry

Tel Aviv University

The nature of the oxide layer formed electrocheaiically on Ru

electrodes in acidic solutions and its electrocatalytic properties for the

oxygen evolut ion reac t ion were inves t iga ted by combined

ellipsometric/reflectometric measurements and by ac impedance measurments.

An automatic ellipsometer employing a rotaintj analyzer and controlled

by a microcomputer was developed. In this system the computer controls the

rotating speed of the analyzer, collects the light-intensity data and

calculates the optical properties of the electrode/solution interface.

This ellipsometrie system was used to follow _in situ growth of the oxide

films. Changes in the optical properties of the interface during constant

anodic polarization or cyclic multipulsing indicate the formation of a

spongy and hydrous RuOx layer. A limiting thickness of 300 A was observed

for films grown by anodic polarization, while cyclic multipulsing results

in a much thicker oxide layer (up to a few thousands A).

Ac impedance measurements provided information about the internal

mediating redox system in this oxide electrocatalyst film. The growth of

the oxide in 0.5M sulfuric acid is associated with a gradual change in the

shape of the complex plane plot, which at small film thicknesses indicates

a distribution of response times due to nonuniformity of the active sites.

For thick oxides the response function describes the charging of a uniform

film with many identical active sites through a simple ohmic resistor. The

effect of pH on the electrode response function suggests that proton

mobility within the films has a strong effect on the surface

electroact iv ity.

- Ill -

COOPERATIVE PHENOMENA IN THE ELECTROCHEMICAL BEHAVIOUROF ANODES MODIFIED BY ANODIC DEPOSITION OF NICKEL COMPLEXES

David A. Issahary and Dan Meyerstein

Chemistry Departments, Ben Gurion University of the Negevand Nuclear Research Centre Negev, Beer-Sheva, Israel

A deposit is formed by anodic treatment of Pt, Au or graphite electrodes in

alkaline solutions containing complexes of nickel(II) with tetraazamacrocyclic

ligands. The deposit thus formed is an electrocatalyst for the oxidation of water

and alcohols.

The electrochemical redox processes occurring in the deposit, which in the

absence of alcohols are well separated from the catalytic process, were studied in

detail. Effects of changing the deposit thickness, pH, voltage scan rate etc. are

reported. A computer simulation of the oxidation of the deposit using a modified

form of the Butler-Volmer equation indicates that the "pseudotransfer coefficient"

for this process is large, cji 10 under some conditions, and depends on the nature of

the anode, the complex used and the thickness of the deposit. Furthermore a correc-

tion term indicating that interactions between the oxidized sites exist has to be

introduced.

4-The effect of the deposit on cyclic voltammograms of Fe(CN) was studied.

Analysis of the results suggests that the deposit consists of nickel complexes

bound to each other via p-hydroxo or oxo bridges and that the deposit behaves as a

semiconductor.

- 112 -

A SEMI-EMPIRICAL METHOD FOR RESOLVING OVERLAPPING WAVES IN CYCLIC VOLTAMMETRY

Gregory Ginzburg (the late), Baruch Zinger and James Y. Becker

Department of Chemistry, Ben-Gurion University, Beer Sheva, Israel

The anodic oxidation of 1.l-dimethylallene(DMA) has been studied in acetonitrile

at a Pt anode in the presence of tetrabutylammonium flouroborate (TEAF) or lithium

perchlorate as supporting electrolytes. In the presence of TEAF the cyclic voltam-

mogram exhibits two moderately separated waves, whereas in the presence of perch-

lorate ions the waves overlap each other almost completely.

The two moderately overlapping waves have been resolved into two separate ones with

equal heights, by employing a semi-empirical method. This stepwise procedure is

based on the assumption that each electrode process is indepenent of the other and

that the rising portion at the foot of the first wave is not interfered by the

second wave.

- 113 -

CYCLIC VOLTAMMETRY OF Pb AND Sn IN SOLUTIONS OF

ALUMINUM BROMIDE AND KBr IN AROMATIC HYDROCARBONS

M. El am, E. Peled and E. Gileadi

Department of Chemistry, Tel-Aviv Universi ty, 69978 Tel Aviv, Israel

The electrochemical behaviour of d i lu te solutions of SnBr2 and PbBro in a non-

polar solvent system consisting of solutions of 1.0M Al2Br6 and 0.80M KBr in e thy l -

benzene was studied. Cyclic voltammograms show well defined peaks for the deposition

and dissolut ion of the divalent metal. Oxidation to the tetravalent state could not

be detected in the available potent ial region. The di f fus ion coef f ic ients wereC O C O

1.1x10 cm /sec for lead and 2.7x10 cm /sec for t i n , as compared to a value of-6 24.0x10 cm /sec for mercury in solutions of toluene of nearly the same viscosity.

An overpotential associated with i n i t i a l nucleation on a platinum electrode is

observed for both metals and electrodeposition does not start unti l n reaches a

value of about 30-40 mV.

In the presence of lead, aluminum deposition is inhibited and does not occur

unti l a considerable overpotential is reached. A value of c«u -70 mV RA1E is

observed for a concentration of 2.0 mM PbB^. Tin, which is deposited at a more

anodic potential does not exert a similar inhibition effect.

The anodic peak depends on the amount of metal deposited in the previous cathodichalf-cycle and cannot be used to analyze the course of the reaction. When thepotential is allowed to reach a sufficiently cathodic potential to deposit aluminumin the presence of lead, a second anodic peak appears, which can probably be asso-ciated with the formation of a thermodynamically unstable Al/Pb alloy.

- 114 -

CALCIUM - THIONYL CHLORIDE HIGH-RATE CELL

R. Tulroan, A. Golan, A. Meitav and E. Peled

Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel

Alkali and alkaline-earth metals immersed in thionyl chloride (TC) solution arealways covered by a surface layer which is instantly formed by the reaction of themetal with the electrolyte. While having a relatively low electronic conduction,this layer has appreciable ionic conductivity and for this reason is referred to asa Solid Electrolyte Interphase (SEI). This SEI apparently determines the electro-chemical behavior of these metals - thereby having a major influence on the proper-ties and performance of batteries which contain alkal i or alkaline-earth anode. Werecently have shown the basic different behavior between the Li/TC and the Ca/TC cellThe Ca/CaCAlCKK-TC cell behaves as an "electrochemical diode", i . e . i t delivershigh current densities (up to 50 mA cm ) in the anodic direction (discharge) butoperates as a high resistor in the negative direction, and during overdischarge(reversal test ) . Therefore, i t is practically impossible to charge or overdischargethis c e l l . In this regard i t should be noticed that high rate lithium cells mayexplode in reversal tests. This is the largest obstacle to the broad use of thesecel ls.

Laboratory prototype Csize (100 cm ) j e l l y ro l l Ca-TC cells were assembled and

tested. At room temperature the cells delivered 3.5 Ah at 0.15 A and 2 Ah at 0.75 A.

The study state value of the current during charging or reversal abuse tests at 25V

was lower than 20 mA (l ithium high rate cells would explode under these tests).

Corrosion tests of calcium at 70 and 25°C indicate a shelf l i f e of 1.5-2 years at

room temperature. The transient minimum voltage at 1.2 mA cm after 14 days of

storage at 70°C was above 2 volts.

Kinetic measurements indicate the fact that the passive layer doesn't thicken

endlessly, but i t reaches a plateau.

INDUSTRIAL CHEMISTRY

- 115 -

PHASE TRANSFER CATALYSIS; FUNDAMENTALS AND RECENT DEVELOPMENTS

Prof. Dr. Eckehard V. Dehmlow, Faculty of Chemistry,

University Bielefeld, Universitatsstr. 25, D-48OO Bielefeld 1

Phase Transfer Catalysis (PTC) is a modern technique of wide

application in many fields of chemistry. The first part of

lecture gives an introduction both into the theory and the

practical aspects of interest for the person who is new in

this field. Choice of catalyst, of solvent, of reaction con-

ditions, methods to remove and regenerate the catalyst are

discussed. A survey is given of the various reactions that

can be performed by Phase Transfer Catalysis.

In the second part of the lecture newer developments are in-

troduced, and focus is put on the work from the laboratory of

the author. The extraction of neutral molecules and acids is

one of these aspects. Further reactions include those with

very strong bases, eliminations, H-D-exchange, additions of

acetylenes, aldol condensations, Wittig and Homer reactions,

novel conversions of diketene, and others.

In the resume an outlook on further developments to be expected

will be given.

- 116 -

PROBLEMS OF SCALING UP TO JUMBO AGITATED REACTORSAND ERGONOMIC INTERRELATION BETWEEN THEIR OPERATORS

AND THEIR ON-LINE COMPUTER

Aldo CantoniElectrochemical Industries (Frutarom) Ltd., Haifa, Israel

When scaling up a reactor in which an exothermic suspension polymer-

ization takes place, it is impossible to optimize all factors to be

taken into account.

The heat transfer surface to volume ratio worsens; control delays

increase because of inertia phenomena; keeping the equal agitating

power input per unit volume causes shears on suspended particles

influencing the morphology of the polymer obtained. A compromise is

thus inevitable.

The ergonomics of an operator confronting the incessantly pressing

requirement of an on-line computer are described. The limit of

stress endurance of an operator constantly required to take decisions

are discussed. Claustrophobic phenomena have to be considered, and

viable approaches have to be worked out to cover emergencies of

various kinds.

- 117 -

b\a

n"D3jiD m v i n ' ^ sa D'^Tia ^m Bin i n on O ^ D S J I D

m c n n {n-»D3Jia m v i n i asm ' " S B n m i p

mo"»nn niD*»'or n^ioa n^DajiD m T ' i n n"7 TOR n

i m o m *7T"ia IJ I3D TIOID D "DJ j im9 D*»3T» "70 a '

' T i o 19DJD3 n m i j n'oajiDn i n

D ' 9 ' m n ,n*»TnoD n n s a OT*n

n <JD3JD m a nn '^s 17<>59n17 Tn

ona D ' ^ O S ' T D'DDna D I C D nss in I T n3TDn ."7TT33

n niD m a i n 'noua RDjmV .TTDDO1? m o m i">a

T»DS7 m i ' D S DDR TST3 131 Tp1? TSH 1 "»3 TIBJlD *7T13n I lTTp

, 1 ' n o 'R*?aD "?aion *?aipD i i D ' n DDR nDis7*7 m m a a a i a ' o rn

n D'spnoai m u mp-«5n nionsna O'DID- 'O! HT ^TDD

l i o n ' s p n o a oa D ' O D O D O " > ' B 3 J I O D ' ^ T T S . n n p i n o

Jt1? 'D3JID iTTD n*7SSn DB DH3 1S13H Tn"7 OSK'TTJl D ' 0 3 *7P

n s n M ' 0 3 JIB K1? 10 i n "73 T S n 1 ? in">3 n"7R 01 ) '7T133 . "»3J1Din

T O ' l i n D D T " 3 D ^ O S A D D ' ^ T I S "JD D ^ i n O D H D ' B l D ' B n "»D HRT3

. T?R D ' ^ T I S "?o nnn m i

- 118 -

an

a , I IM I .n ,qinj»B .n

n •> s p n

n . - lq. = K.C. [X a . . C . ] 1

in n>n»n no>ana

nD*iyn * i i ^ ramp nmayn nnniaw ira^ana an nn^oo nannu>K

^a na n>a>ana an

i»n n. - i Ki nn^ao >j?iap .Van nanmnKb ns1* ia»Knn ni'^io^a immn

m nanyaa > u ba may i^apnnw aj^. nmnn »anpn I^'KI a>ana bi bv n»a"»ana nn

.n»a»ana nbt\ nanya

cat G< a<.cu' cut a* C^LL. tci, cutL uass axtuui cttu dal ( dLau=9*i. a,,a ) •

QtdLlOdLG, H^daLLE* QlLd (*W*3*S ) 'CtOtlClU UX^U a^GflLLU HU dCt&I UUG^ttua ffl^ 4QLLLU

Liac*. cumLfca a«.ai! ui.au ^uccu uda^aa ^»iu uu^mucU 4^44 tcL4du uda^toa c£4i.u

HO

cu uda^ta«.u ( as<j ) • ucu dai

uurictu 4M1L U4i«LL4iJ n

UQ4CU C4

aLi.il

0o00V 'VlVUtLCli ^ LSLtU

n ut ml dita

XUL a^

UttCU XL LCL, ) * QtT

^ ^ ; urtcu jjau QULUAU cdru

ctci. 5(J4 r^Lau LdaLuwa am. auLLta dai^a tjui.#

a^ «sU4 uas4 a^ x^ict4tu da^^atu* U4» uncu

„ UQCC4C 1JUUC(.XU4 N/BL Ct, ,C UQZS (

uricu GQit tscut ajnssoxo 3in;.i pus

uaucu4 ( G^CUCU' G^L4ta* LC4LQ4 utactta tct, )* uuxicu u&t*u L'*n urtcu

uricLU u^d4tu uauLuam cdu L£iru xuu* UTLCU »UU ( tuxLLTtxtu KL i.u*Ltircx4U )

LUtU (S,,4 dQ^tOQ C£^ UGd4L CGL^* <S,,4

o i , <>4uu UQL^I u.Ncr * puog*o*0 u«.utL4U UL&U ^uacuu urtctu

CLS^L: ^iC4CLQ4au cl ttuttl cere* uactl ^audu

UJtXLLtli 0^ CLCL (QHOff-)

' aaau;Ll

0 - 6X1 -

- 119a -

1 Cr

2 Pt

jn n»npn ma^snnn n*c mtnb -IWSK nVapnn -TOK

•(line scane profi le) L«S#P,

«a

(1) n ' ano in sV rnaVsnr. rDins TTS? S . L O P .

n eyoo maVsnn taa^DVs -nay S.L.P.

—D .-inT» p*no3 C I D D n o » Vc? imaVDnn ns 7"DKV '•na wrn »pna JWID oaain npnon

n'amon maVsnn Kin winn awion «( *wKnn 3»DID ) j n j n mpaa nj^cVsn ^c nmaVsnn !?y n a n

leas n»rmp3 IK ir»aman niiVsnn ns .nV"»ann n ' n p n maVsnnno naiwn ,n»mip3 IR

nuVsnn nms ^ya n a i n *ni? 7*»2 D'Vian^ fnan1? I-DK P T I TJT»^ ,^is 'on n m c n :

^ na'uVsn VTO nnmcn na^annr; iccana ^n i*»Vnn2 atnnu ms^nr.

K Vo

nn Vw mxpaisa D'ITO nmay ^Kjna naiann >E? m'ua'pn niKsinn nt is io

n isioa n»iVn ivy. na'oVsn VP n'impa IK n»amz>n

- 120 - 0

Converting of alkyl chlorides to alkyl bromides by PTC

Influence of PTC ofi equilibrium position of reversible reactions

M. Weiss-Yonovitch and Y. SassonThe Casali Institute of Applied ChemistryThe Hebrew University of Jerusalem

Halogen exchange reactions between inorganic halides and alkyl halides

(Finkelstein reaction) are equilibrium reactions and are not effective for

converting alkyl chlorides to alkyl bromides since no simple methods are

available for shifting the equilibrium in the desired direction.

The present work has utilized the technique of PTC for synthesis of

alkyl bromides from alkyl chlorides and aqueous or solid bromides with quaternary

ammonium salts serving as PT-catalysts. This work also demonstrates how PTC

may influence the equilibrium position of reversible reactions.

A typical process may be interpreted by the following equation:

p ri + 1 raB-r <PTC> catalyst R_Br + I r_riR C1org + 2 C a B r2 aq. or s. ' K Br 2 L a C 12

The reactions were carried out in a two-phase system at temperatures of 90-130°C.

In typical examples benzyl chloride was efficiently converted to benzyl

bromide, allyl chloride to allyl bromide, dichloromethane to chlorobromomethane

and dibromomethane, n-octyl chloride to n-octyl bromide.

Parameters such as temperature, rate of stirring, solvents, concentrations

of CaBr- in water and its quantity, and also the catalyst structure and its

concentration of the quilibrium position and the rate of the reaction have been

investigated.

- 121 - 0

GAS PHASE HALOGEN EXCHANGE IN ALKYL HALIDES CATALYZEDBY SUPPORTED MOLTEN PHOSPHONIUM SALTS

L. Mendelovici and Y. Sasson

Casali Institute of Applied ChemistryThe Hebrew University of Jerusalem

Exchange of chloride by bromide was achieved by passing mixtures of alkyl

bromide with alkyl chlorides over supported quaternary phosphonium salts. Typical

active catalyst was prepared by supporting 5-10Vw/w tetrabutylphosphonium bromide

on alumina. By passing, for example, mixture of ethylene dibromide and ethylene

dichloride in a tubular flow reactor at 150° over this catalyst equilibrium

conversion can be obtained at space velocity up to 1500 GHSV according to the

following equation:

BrCH2CH2Br + ClO^OLCl ^ = S : 2 BrCH2CH2Cl

This method will allow the application of EDB as a bromination agent for

production of simple alkyl bromides from the corresponding chlorides in a flow

system. The Following mechanism is proposed:

C1CH,CH,C1 + QBr F = * ClCH,CH,Br +-QC12 2 k2 . . '

BrCH CH Br + QC1 * = ^ ClCH7CH9Br + QBrk4 L L , .. .

This mechanism is in accordance with the following apparent rate equation:

rate = kC2 - k'.(Co - C ) 2

where k = k' = —2(k2+k1+)

C = [EDC] Co = [EDC]'o

Details regarding the mass transfer effects, thermal stability of the catalysts:and the role of the support were also investigated.

- 122 - 0

FLAME RETARDING PROPERTIES OF THE BLOCK COPOLYMERS OF

BROMOSTYRENE (BS) AND STYRENE (St)

Itzhak Koenigsberg and Joseph Jagur-Grodzinski

Department of Plastics ResearchThe Weizmann Institute of Science, Rehovot

Flame retarding properties of block copolymers of BS and St have been foundto be superior to those of their random copolymers and of the blends of the res-pective homopolymers. Block copolymers were prepared using the anionic polymeri-zation techniques (1). Side reactions, due to the susceptibility of the C-Br bondin BS or in poly-BS to nucleophilic attack (2-4), were avoided when the polymeri-zation reactions were conducted in dark at -78°C with "living" carbanions asinitiators.

Polymerizations of BS were completed within few seconds and high molecularweight polymers with narrow molecular weight distribution (Mw/Mn = 1.04) wereobtained. Controlled elimination of bromine leading to the formations of thepolyphenylacetylene segments was induced by keeping the unquenched "living"carbanions in dark at -21°C.

no PS + PBS D. , ^ Random nDCPS ,,, ,. Block copolymers , PBS(blend) _____ copolymer

52 100

24 38

(a) According to ASTM Standard D-2863/77.

LOI indices summarized in the table indicate that BS in the block copolymeris more effective than in the randomly distributed copolymers or in the blendsof homopolymers. Apparently, spacial distribution of the BS domains may affectsignificantly the flammability of the material.

References

1. M. Szwarc, Carbanions, Living Polymers and Electron Transfer Processes,Wiley, New York, 1968.

2. C D . Sargent, Tetrahedron Letters, 3729 (1971).3. J.F. Bunnett, Accounts Chem. Res., lj^, 413 (1978).4. W.J. Trepka and R.J. Sonnenfeld, J. Organomet. Chem., 16_, 317 (1964).

Fraction ofPBS (W%)

L O I ^

none

17

50

21

31.5

23

35

24

43

27

- 123 - 0

THE CHEMICAL HYGIENE OF PROCESS SOLVENTS

II. SYSTEMS CONTAINING TERTIARY AMINES

L.M. Shorr, J. Segal 1 and Z. Blutstein

IMI - Institute for Research and Development

A primary requisite for a process solvent in the manufacture of large

volume industrial chemicals is its chemical stability. Decomposition not only

represents a material loss, but contaminants produced in even very low concentra-

tions can cripple process operations. Reactions which proceed at a rate of

only a few percent a year receive little attention in the chemical literature.

Long chain alkylamines find extensive industrial use as liquid ion-

exchangers, extractants in hydrometallurgy and the recovery of acids from both

aqueous process and waste streams. On the other hand, the anti-oxidant activity

of the amine function suggest a decomposition pathway which might interfere with

the performance of industrial solvent extraction operations.

The oxidation chemistry of tertiary amines, examined for use in such

applications is very complex. Oialkylamines, aldehydes, enamines, formamides,

olefins, hydroxyamines, amine oxides and various condensation products can form.

The extent and nature of the reaction in any given solvent stream is influenced

by its composition and the conditions to which it is subjected.

An overall scheme, descriptive of the chemical breakdown process was

evolved. The measurement of oxygen uptake rate was found to be both a simple

and sensitive tool for the evaluation of the susceptibility to oxidation of any

given amine system.

- 124 - 0

-njpn pip*TO n^pyn

, i omnsmya

p bench-scale 'mnyn nnjp3 Q>»io>jn >K?»n o » n m »

ibbs o»3»^win .oaji^ pipT 'nn >3SB !?i£>u t>y ipnn ni>onn p i l o t plant

CD«A.F) onin

bv nnK 90 D npmn D>*te?3N0 onia

miayn .ooia V I K n^xoi^a oy nKiiwr naiyai Tmin n»u< n^^oiba i»bnn D>

npnin

bv ni^A nprnn Tin O>>JAIIKI D>^uo*pn n^oniy bv an*i oinnn nnK 90

- 125 - 0

INFLUENCE OF CHLORIDE IN PHOSPHORIC ACID ON THE CORROSION

AND ELECTROCHEMICAL BEHAVIOUR OF IRON AND NICKEL ALLOYS

M. Schorr and E. Weintraub, IMI-Institute for Research and Development, Haifa.

Phosphoric acid is an important industrial chemical used as an intermediate in the

fertilizer industry, for metal surface treatment in the metallurgical industry and

as an additive in the food industry. Wet process phosphoric acid (WPA) is produced

by attack of sulphuric acid on phosphate rock. The composition and purity of WPA

depends upon the composition of the rock and the sulphuric acid used. Impurities

such as chloride ion, arising either from the rock or the wash water, fluorine

compounds originating from the fluorapatite, and the operating conditions^ ,

increase the corrosivity of WPA during the production stage.

The influence of chloride ion on the corrosivity of 42%, 55% and 70% H_PO. has been

investigated by corrosion tests in H_PO. solutions containing chloride ion in the range

0.05-1.0% Cl . Corrosion tests we.re also carried out on filter and concentrated acids

obtained in industrial and pilot plants. The corrosion and electrochemical behaviour

of AISI types 304 and 316 and high-alloyed austenitic stainless steels and Ni-base

alloys, in Cl-containing phosphoric acid has been determined by weight loss measure-

ments, by measurements of metal electrode potential as a function of immersion time

and by potentiostatic anodic and cathodic polarization, in the temperature range 70-120°C.

The alloys tested exhibit passivity in solutions of pure H P0. but in the presence of

Cl ion breakdown of the alloys' natural passivity occurs with the onset of active

corrosion. The electrode potential of the alloys shifts,from the passive to the active

state, at a rate and magnitude, directly related to the Cl" content of the H P0. solu-

tions. The values of the electrochemical parameters of the potential-current plots

reveal anodic dissolution or passive behaviour, and vary in accordance with the Cl

concentration and the corrosion rate.

Results from gravimetric and electrochemical tests will be presented, the types of

corrosion will be described and their practical significance will be discussed.

REFERENCE

1. M. Schorr, Corrosion Manual, Part One: WPA, Corrosion Testing and Control in

Fertilizer Intermediates and Products, IFDC, Muscle Shoals, Al. (1981).

- 126 - 0

WATER AND SALT TRANSPORT THROUGH AN ION-EXCHANGE MEMBRANE

T,S. Brun (present address: Chemistry Dept., University of Bergen,Norway),and

A. Berg (present address: israel Desalination Engineering,Tel-Aviv, Israel)

Michigan Technological University, Houghton Ml, U.S.A.

Linear non-equilibrium thermodynamics provides membranology with a useful means

of analysis of transport processes. For transport through membranes, Onsager's

relations between fluxes and forces, which are of general nature, seem to hold

quite far from equilibrium and can therfore be applied to many practical process-

es. Michael i and Kedem (i960 adapted Onsager's(J.=£ L. .F.)equations to a

simple membrane/solution system.

Schmitt and Spiegler (1975) used the Michaeli-Kedem equations to produce

a set of equations that enables the calculation of the conductance coefficients

L , which characterize the transport Behaviour of the system. Five groups ofxymeasurements are necessary to provide the experimental data needed for the cal-

culation of these coefficients, viz. (•) membrane electrical conductivity; (b)

electromigration-electroosmosis; (c) osmosis-dialysis; (d) hydraul?c permeability

and (e) streaming potential. All of these experiments but the first group can

be performed by the "concentration clamp" method developed by Spiegler and

Colleagues since the late 196O's (A. Zeiman et al. (1971)).

Further development of the system was achieved by simplifying the apparatus

which allowed shorter experiments and easier salt-concentrat ion control in onesolution compartment. Quantftfve characterization of the system

M r, . . , I Cation exchange membrane Iatl solucion c

s |CL-25T (Tokuyama Soda Co.) | NaCl solution c"s

demonstrated the usefulness of the modified method. The results obtained were

compared to the results of studies with the membrane C-103, (American Machine

and Foundry Co.). The "diagonal" (Onsager-type)conductance coefficients of the

membrane CL-25T were found to Be larger than those of C-103, which indicated

higher permeability. Onsager reciprocity relations were validated in the studies

with both membranes.

REFERENCES

1. Michael i, I. and 0. Kedem, Trans. Farad. Soc. 57J185 (1961)

2. Schmitt, A. and K.S. Spiegler, unpublished results (1975)

3. Zelman, A., J.C.T. Kwak, J. Lfebovitz and K.S. Spiegler, Experientia

Suppl. J8., 676 (1970

ACKNOWLEDGEMENT

Prof. K.S. Spiegler, from the University of California, Berkely is highly app-

reciated for leading and guiding this research.

- 127 - 0

SIMULTANEOUS REACTION AND DISTILLATION IN A PACKED COLUMN

R. Neuman and Y, Sasson

Casali Institute of Applied Chemistry

The Hebrew University of Jerusalem

Most industrial reactions and separations take place in different zones

whereby reactions are first completed and then products are separated, e.g.

by distillation. A significant savings in equipment and energy can be

obtained by conducting both reaction and distillation in the same unit.

We have studied the continuous esterification process of diluted acetic

acid with methanol to yield methyl acetate according to

CH3COOH + 70H CH3COOCH3 H20 (Keq =5.4)

The reaction was carried out in a six theoretical plate-column packed with a

combination of solid catalyst (acidic ion exchanger) and regular column

packing. The conversion and the purity of the product were measured as a

function of reflux ratio, feed concentrations, location and rate and quantity

of catalyst. At optimal conditions up to 98% conversion could be obtained

with 1001 purity.

A mathematical model was built which takes the rate equation of the

reaction along with thermodynamic properties of the system components and

physical variables (reflux ratio, feed rate and location etc.) and calculate the

conversion and the purity of the products. Quantitative data will be presented

in the lecture.

- 128 - 0

Crystal Structure Modification of Saturated Fats by Food Emulsifiers

by: Edna Wellner, Nissim Garti, Sara Sarig.

Casali Institute of Applied Chemistry

The Hebrew University of Jerusalem

Ordinary, molten fat when cooled will crystellize in the metastable

ot-form. This form transfers during storage into the more

thermodynamically stableB-form. The polymorphic transformation can

cause texture problems in the food industry based on fat.

The present work investigates the effect of several emulsifiers as

crystal structure modifiers,in preserving theo(-form of pure tristearin.

X-rays powder diffraction and D.S.C. techniques were used in order to

evaluate the emulsifiers effect. It was shown by both techniques, that

when 5wt. % of SPAN 60 (sorbitan monostearate) were added to the molten

tristearin before cr/stallization theo(-form did not undergo phase

transformation into the f -form and most of the fat consisted of the

original modification aven after prolonged self life storage.

Increasing the amount of the emulsifier to 15%, prevents any transformation

from ad-form into the &-form.

Several pther emulsifiers have been tested and it has been found that the

combination of bulkiness of the hydrophilic groups with tke right lengths

of the hydrophobic chains of a given emulsifier are necessary to preserve

the oC- modification. Liquid emulsifiers and those having a pronounced

hydrophilic character will not be efficient as crystal modifiers.

- 129 - 0

Emulsifiers as Weighting Agents

By: Z. Kraus; M.Frenkel; N. Garti

Casali Institute of Applied Chemistry

The Hebrew University of Jerusalem.

Emulsions are inherently unstable, meaning that in the course of time

droplets will coalesce and ultimately water and oil phases will separate.

Coalescence is accelerated when there is a difference in specific gravity

between the two phases, promoting creaming which will concentrate the

droplets. In a case of oil in water (O/WJ emulsion, where the oil is

lighter than water, oil droplets tend to rise to the surface of the emulsion.

The final step-coalescence, or breaking of the eimilsion, involves the merging

of the droplets to form larger clusters and ultimately a complete destabilization

of the emulsion occurs. The creaming phenomenon can be prevented by equalizing

the specific gravities of the oil and water phases.

A new concept was developed at the Institute which combines the Weighting

and emulsifying functions in one cpmpound. An example ii the use of

bromination to increase the specific gravity of commercial surfactants.

Various commercial emulsifiers, both ionic and nonionic were bronlnated and

the physical properties (e.g. specific gravity, Iodine number, Acid value,

I.R) of the new compounds were determined. Their surface properties', such

as critical micelle concentration (CMC), surface excess concentration (P),

area per molecule (a), efficiency (PC,J and effectiveness, were examined

and found to be slightly lower than the unbrominated ones. Eventhough,

these new surfactants proved to be useful emulsifiers by using them for

the preparation of most stable 0/W emulsions.

By using proper amounts of the new emulsifiers-weighting agents the specific

gravity of the oil droplets is equalized to that of water. No creaming

occurs in such a system. Larger amounts of these emulsifiers - weighting

agents in the system (3.5wt.\ . of the nonionic emulsifiers, 1 wt. % of the

anionic emulsifiers) increase the specific gravity of the oil droplets to

values higher than one. Consequently, sedimentation (rether than creaming)

occurs, being a substantial proof of their weighting property.

- 130 - 0

Dispersing Agents in Aqueous and Organic Systems

By: H. Isaacs, N. Garti and M. Frenkel

Casali Institute for applied Chemistry

The Hebrew University of Jerusalem

The action of dispersing agents for solid particles in a fluid medium

has long been a matter of trial anf error based on very limited theoretical

work. In this series of experiments an attempt was made to systematize the

interaction of polar and non-polar solids and fluids, with the effects of

different types of dispersing agents on each.

The polar solid was calcium carbonate and the organic solid was polyvinyl

chloride. Liquids were water and heptane. In each case a 50% by weight

slurry was prepared and its viscosity measured with incremental' additions

of various dispersing agents. In this way it was found that sodium lauryl

sulfate is a very effective dispersant for PVC in water but a very poor

one for calcium carbonate in water. Tamol 731 is quite effective for both.

Lecithin is effective for both materials in heptane, while Tween 80 is a

dispersant for PVC in heptane but not for calcium carbonate. The results

were explained by the tendency for the dispersing agents to be absorbed

on the particle surface and electrokinetic potential changed.

Further work should enable the choice of optimal dispersants in paint

formulation, wastewater treatment and paper coating.

- 131 -

SYNTHESIS OF DIALKYLPHOSPHORIC ACIDS FROM

P0C13, P2O5 AND ALCOHOLS

J. Segal 1, L.M. Shorr and S. Weiner

IMI (TAMI) - Institute for Research & Development, Haifa

Dialkylphosphoric acids are of commercial interest mainly for metal extractionand as industrial intermediates. They are commonly prepared either from PpO,- or fromPOC1- and the respective alcohol. In both cases monoalkylphosphoric acids areco-produced and tedious separations are involved.

By using equimolar amounts of P20c and POClg, generally in the presence of anamine, followed by the addition of an alcohol, a variety of essentially pure dialkyl-phosphoric acids were prepared in approximately 90% yields. It is assumed that pyro-and/or-polyphosphoryl chlorides are the intermediate species from which the dialkyl-phosphoric acids are formed.

- 132 - P

Preparation of Monoglycerides of Fatty Acids from

Epichlorohydrin by Phase Transfer Catalysis - Part I

By: Y. Sasson, N. Garti and A. Aserin

Casali Institute of Applied Chemistry

School of Applied Science and Technology

The Hebrew University of Jerusalem

91904, Jerusalem

The existing industrial reactions for preparation of monoglycerides

of fatty acids are based on acidic or basic catalysis at elevated

temperatures and prolonged reaction time. The product is an equilibrium

mixture of isomers which needs further expensive and tedious molecular

distillation.

The following study presents a suggestion on a new selective method for

preparation of pure monoglycerides of fatty acids. The reaction is

based on treatment of epichlorohydrin with sodium stearate soap in the

presence of various phase transfer catalysts.

Over 90% of pure monoglyceride is obtained in quantitative yields after

short reaction time at relatively low temperatures.

The effect of reactants ratio, catalyst type and concentration, temperature

and industrial aspects have been investigated.

- 133 - P

Multiple Emulsions: A Novel Technique toOvercome The Unpleasant Taste of Drugs

R. Shwartz, M. Frenkel and N. GartiThe Casali Institute of Applied Chemistry, The Hebrew University, Jerusalem

A multiple water-in-oil-in-water emulsion (W/O/W) is a water-in-oil emulsion

which is further dispersed by the aid of proper emulsifiers in a second

aqueous phase. This emulsion contains water droplets (0.1 - 2*m) which are

surrounded by an oil membrane.

In OTder to mask the bitter taste of a drug, it must remain in the inner

water phase since preparation ("Yield of Preparation") and for its total

shelf life ("Stability"). Furthermore, the drug should be completely

released upon reaching the stomach.

Many W/O/W emulsions were prepared using ionic and non-ionic emulsifiers.

Their suitability for use with the drug (chloropromazin hydrochloride)

was examined. The yield of preparation and stability of the various

systems were tested by dialysis of the multiple emulsions and by quantitative

analysis of the drug.

By using non-ionic emulsifiers the yield of preparation did not exceed 85%

Cleaning that 15% of the drug is present in the continuous aqueous phase)

although stability was 100% (no further drug was released from the inner phase).

The optimal solution was found by using a combination of ionic and

non-ionic emulsifiers. The results obtained were: Yield of preparation

of 100%, storage stability of 100% and total release of the drug in

synthetic gastric juice.

- 134 -

EXTRACTION OF ALKDXIDE IONSBY LIQUID ANION EXCHANGERS

E. Pross and Y. Sasson

Casali Institute of Applied ChemistryThe Hebrew University of Jerusalem

When organic solutions of lipophilic quaternary ammonium salts (liquid

anion exchangers) are treated with aqueous caustic solutions only negligible

amounts of the hydroxide ion are extracted into the organic phase. The

behavior of this anion is thus different from other anions, namely halides,

perhalides, nitrate, etc. which are easily extracted under similar conditions.

This observation is changed when small amounts of primary alcohol is

added to the system. Very strong bases are obtained in organic media when

50% aqueous sodium hydroxide is extracted with toluene solution of tetra-n-

hexylammonium bromide containing 2-5% of alcohol, e.g. ethanol, n-propanol,

n-butanol or benzyl alcohol.

Based on quantitative measurements we propose the following mechanism

to describe this phenomenon:

(1) Distribution of the alcohol between the organic and the aqueous phases.

(2) Acid-base equilibrium in the aqueous phase according to:

ROH + NaOH ?=* RO~Na+ + H20

(3) Extraction of the alkoxide ion with the quaternary salt by anion exchange:

Q+X"(org) + R0"(aq) =s=* Q+OR(org) + X"(aq)

where Q is the quaternary cation and X is its original paired anion.

A suitable parameter to describe the extractability of RO" relative to

that of X" is Ksel defined by:M DQaq

[0X]org [RO-]aq

This constant was measured for several alcohols and its magnitude implies

that alkoxides can be efficiently extracted by various combinations of

solvents and quaternary salts.

rniy3 n Vo?

- 135 -

(crystailinity) nr>p

jiaan ,aaaa

oa

njr»ap :

7a

—in

(A100H)

na aaanV 7n*an "\x , (tr»Dpitta

•v*opiKan V

T»KB

nnapV

a^ana) yaoa KXBX *TOK 9 (Bohmite)

naanV nni»a aiwin oVa nain icm

a»anaa j?aca p-y KXBJ (Diaspore) msoK-»T .2

(crysta l l in i ty)

(shifting) p-»sn nnon

Z.R.D

naan

nysin

nsoa

,o-»-»sipona»nn o'an

Van "»xn Vc a m i

oa

*n •^n^•» nnon ,

D.T.G, n D.T.A. moippa

:IVK mys

maipya jr»sia TWK t(n*opm*n-*DpiKn V© *mnn pn»sV ncrpa n&s) •pKnn p»sn Vw K»E7n nnDT? -

J),T.G, T D.T.A.

w Vr ^<» Da'>cK^ -

IT nairm oa .p'sn

) »win p-»sn "npnipav? n»iTn Vma -

. K-\ .isnVn jwna'an i m a naopn Dy nVnai nsVm IT n»iT.D,T#G. i D#T»A, niaipya

*WT» mp»ia «aan Bi»*na wia^an m*aa mVna nanwo IT II'ITH Vniaw Kxoa HT ipna nVnaa

via*an m*aa o*"»ia*roV i t n»it »"»ia»w Vn? mwanrtw in*ain ,naiw cia»a IIT»D mVya m o a n 20 a

oniKa lys ia n"»ann HT'VJK V© mp»iaa .iVw n»ni3D»cKD IK p»s irnt; bv innono m v nmaa K'n

*l*iana . D,T#A#a oa V»apaa npiaa »Kaan Va .mKxmn nK rnwnV n"»a» ^n aw *ia miay *»Kan

•Van *sn Vw ann oa yapa

CULU r*cta rcmu C«.CLC*U caicu

sdiaiu

UU2tU

0. OVS

/

GtXt

^ LLUC US* ut^» <Juau isu* w.$.id a^ a«au ULUC ut*.

ZULCU Si. L t * -

I.S.I. ISRAEL SCIENTIFIC INSTRUMENTS LTD. TT01 TtOHn 'DID 1WDD

52 306 l l |Tn 341790-.OP^U 772051-2-3^U |A-nm,17 OniD 3 i m

VISTA 6000 Gas Chromatograph

The newest, most advanced,most accurate GC availabletoday.Based on world reknown 3700series.

- Dual column standard, up to4 simultaneously option.

- Specially adapted for allmodern capillary columntechniques.

- Microprocessor, preprogra-mmable, auto zero, autoinjector and many other

TO BE SEEN IN ISRAEL IN MANY PLACES IN WORK state of the art'features.

Ask us about the new H P L C Detector UV-100, scanning, programmable andvery small.

A P A AM ADVANCED TECHNOLOGIES LTD.irui mmpnn ni'Mmo NQN

TEL. 03 -226788.222691 ."7U TELEX: 32366 Rial i l . : Dp^U 61211 D'ON-to 21205.1.11 P.O.B. 21205, TEL-AVIV. ISRAEL

DESIGN YOUR HPLC SYSTEM WITH WATERS MODULES

HPLC FOR ANALYSIS OF: O ORGANIC SYNTHESIS

O POLYMERS/ADDITIVES

O ENERGY

O HOSPITAL/CLINICAL LABS

O FOOD

O PHARHACEUTICALS

O ADHESIVES/COATINGS

O ENVIRONMENT

O BIOLOGICAL/B1OMEDICAL

O AGRICULTURE

MILLIPORE Waters, The Liquid Chromatography People

LACHMAN PROCESS EQUIPMENT LTD. nwV3 •3'^flXl 1VXP.O.Box 1308 47100 Ramat Hasharon Israel 47i00im>nnm 1308 .7.n LPE

LIGHTNIN

PUlSAfeeder

RUBBERco BIRD

iNiiETilil mPUMPEN

,na->Kip

nnsni

mm on

. 5 31DT13 ' m 7\22y\2

052 - 37163 TTSVO

471CX) m w n n m ,1308 .T.n

MEDTECHNICA LTD.'DQIX .THIlLm ,^131 1VX

T2X-'7T\ 8 Dl7Wn 11161 026 HWTi 2695 " rn

TEL. 331263-8 7D

p H LDC/Milton Roy

IDR

C^LiMIEJ:INSTRUMENTS COMPANY

_ HPLC-1? m ' i ? m o mDiyo

TittDO - ULTRA VIOLET PRODUCTS,IINCnn®San Gabriel. California 9177f l iy j

.91010 Q^IJIV,222862,222059.i>0 ,1147 .T.H 1226147 ^

DESAGA- SCHOTT: TLC, Isoelectric Focussing, 20 and 48 FractionFlow 5 Immunoeiectrophoresis, UV lamps,Peristaltic Pumps,pH Electrodes,Viscosimeters,Titration and other laboratory ware.

NUCLEAR ENTERPRISES: Sample counter (96 samples counted in sixminutes).Nuclear and Health Equipment.

CEPA : All-purpose Laboratory 5 Industrial centrifuges.SARGENT-WELCH: All kind of laboratory ware § Vacuum pumps.TOWNSON 5 MERCER: Laboratory § Pathological ware.SHANDON:GALLENKAMP: Comprehensive range of laboratory ware.JENCONS: Water Stills,Homogenisers,Pipettes,Dewars,

Dessicators.ELECTROTHERMAL: Heating Mantle/, Tapes, Laboratory ware, New

Model Fraction Collector ( 500).Gradient Formers,etc.

OHAUS SCALE CORP: Manual and Electronic Balances.TINTOMETER: Spectrophotometer Cuvettes, Colorimeters,

Water Tests.WHATMAN: Filter papers, Glass-Fibre Micro Circles,

Ion Exchange, Membranes,Cellulos-Separations,Columns, Media for HPLC.

WHEATON: Laboratory Glassware bottles § IndustrialEquipment.

BIO-RAD: Chromatography, Electrophoresis, Hollow Fiber,Columns, Membrane Filtration § Immunochemistry.

WOELM PHARMA: Alumina, Silica-Gel, Glass § AluminiumPrecoated plates.

Glass, Porcelain, Plastics, Pathological Ware, Flow-Meters,Stoppers, Dewars, and Chemicals.

ANALYTICAL CHEMISTRY

- 136 -

THE ANALYSIS OF SEAWATER FOR TRACE METALS - A CHALLENGE TOANALYTICAL CHEMISTS

S. Berman, Division of Chemistry, National Research Council ofCanada, Ottawa, Canada, K1A 0R9

The analysis of seawater for trace metals has long been a challengeto analytical chemists. Problems are the inherently low metal con-centrations (submicrograms per litre), the complex matrix containingup to 3.5 percent dissolved solids, as well as sampling and storage.

This laboratory, under the auspices of the National Research Councilof Canada's Marine Analytical Chemistry Standards Program, has overthe last few years developed a series of procedures for concentra-tion, separation and determination of a number of trace metals inseawater of interest to marine scientists. These include methodsinvolving chelation-solvent extraction, ion exchange chelation,immobilized ligand chelation and determinations utilizing atomicabsorption spectroscopy, inductively coupled plasma - opticalemission spectroscopy and isotope dilution solid source massspectroscopy.

A highlight of this work is the recent production of the firstseawater reference material for trace metals, NASS-1, which is nowbeing distributed internationally.

- 137 -

ANODIC STRIPPING ANALYSIS APPLIED TO ENVIRONMENTAL SURVEILLANCE

Magda Ariel

Department of Chemistry, Technion - Israel Institute of Technology, Haifa.

Anodic stripping analysis and its advantages for trace metal analysis in a

variety of environmental matrices and in particular natural waters are discussed.

Recently developed approaches and instruments, which enhance the technique's capabil-

ities, are described. The survey includes subtractive methods based on the use of

different deposition times or different convection rates at twin matched working

electrodes dipping into the sample cell; flow-through cells for the analysis of a

succession of discrete samples or the in situ monitoring of traces of heavy metals

in aqueous samples, using rotating disc electrodes. A combination of a specially

designed flow-through cell with fixed mercury film glassy carbon disc electrodes,

used in the differential anodic stripping voltammetry mode, is shown to provide a

simple, stable and precise tool for the automated monitoring of sea water samples.

-8 -9In the 10 -10 molar concentration range, 1-5 min deposition times suffice for

lead, copper, cadmium, etc. determinations (s.d. 4%), total analysis time per sample

ranges from 2 to 6 min. This efficient sample through-put (10-30 samples hr ) allow

reliable in situ monitoring to be carried out, using a relatively simple, inexpensive

experimental set-up.

(Withdrawn) - 138 - 0

THE FORENSIC CHARACTERIZATION OF PAPERS BY THEMEASUREMENT OF CELLULOSE CRYSTALLINITY

by

H.A. FONER

The Geological Survey of Israel, 30 Malchei Israel St., Jerusalem.

and

N. ADAN

Criminal Identification Department, National Police Headquarters,Jerusalem.

The identification and characterization of different types of paper is ofobvious use in forensic science. The main constituent of paper is cellulose fibreand the degree of crystallinity of the latter is a function of both the specificraw material and the manufacturing process.

The degree of cellulose crystallinity was measured using X-ray DiffractionSpectrometry (XRD). A special holder was developed for cutting down backgroundreflections and the technique is rapid and non-destructive. With a suitable XRDspectrometer the method may be used for large or small samples.

Cellulose is characterized by a diffraction pattern containing three distinctpeaks at 22.5°, 16.3° and 14;5° (29), (Cu K radiation). As the cellulose fibre isdegraded (e.g. mechanically in a paper-making machine) the degree of crystallinityis reduced causing corresponding changes in the XRD pattern. The measure ofcrystallinity chosen in this work is the Crystallinity Ratio defined as:-

C.R. = *J - "SluiIMax ~ """Min

Where I and I . are the intensities of the 22.5 peak and the 19 minimumrespectively on the diffractogram.

Experiment shows that the crystallinity ratio is affected neither by thethickness of the sample nor by its orientation in the spectrometer. Results on avariety of documents show that the suggested technique is a useful addition to themore conventional methods of paper analysis.

- 139 - 0

A.LORBER and Z. GOLDBART

Nuclear Research Center Negev

Elimination of Drift from Analytical Signals in Multielement

Analysis by the GISM (Generalized Internal Standard Method)

Internal standard is added to samples during analysis to stabilize analytical

signal in emission spectroscopy, by refering to the ratio of signal to

standard as analytical signal. The method was used widely in emission

sources as d.c. arc and spark, but to a limited extent in the relatively

new sources ICP and DCP.

The internal standard method needs however a pair of spectral lines having

similar physical parameters. When simultaneous multielement determination

is performed, the error might increase instead of decrease due to variety of

spectral line parameters.

A method for correction of drift based on few internal standard will be

presented. Experimental data shows,reduction of drift from 10% to 0.1%

using ICP emission system. The spectral lines were chosen non dependent

on physical parameters.

- 140 - 0

Determination of Carbonate/Bicarbonate Ratio by C NMR

Raphael Bar* and Yoel SassonCasali Institute of Applied ChemistryThe Hebrew University of Jerusalem

Summary

A linear relationship between the molar fraction of carbonate-

bicarbonate in an aqueous solution and the chemical shift of the C

n.m.r. peak has been established. This phenomenon was applied for the

determination of the sodium carbonate/bicarbonate ratio without and in

the presence of other salts, as sodium formate, sodium chloride and

potassium nitrate. The method is applicable to solutions where the

overall carbonate concentration is known and it yields errors of

carbonate molar fraction between 1.81 and 2.8% which may be reduced

by a more precise n.m.r. system.

- 141 - 0

MICRO DRY ASHING FOR TRACE SELENIUM DETERMINATIONIN ORGANIC MATRIXES

Dr. E. Shoeriberger, J. Kassowitz

National Physical LaboratoryThe Hebrew University of Jerusalem

Since the 50fs it has been known the importance of selenium for normalplant growth and functioning of animal organism. Apart from the overall bene-ficial biological role of selenium, it was established that this element playsa protective role in poisoning with heavy metals C1U.

At present, sodium selenide is used at doses far below toxic in many coun-tries in breeding farms for prophylactic and therapeutic purposes.

A great deal of application work has been published for the detection ofselenium on a variety of matrixes, as water C2D, waste water C33, and biologicalmaterials Zkl.

The small amounts of selenium present in environment and his volatility,complicate the determination. Selenium is lest almost during every pretreatmentprocedure known till now CUD

Determination of ng amounts of selenium in mg amounts of organic matrixeswas studied, using a flameless AAS method.

Chemical interferences due to the organic matrix was eliminated by workingout a micro dry ashing method, using an ethanol solution of magnesium nitrateas ashing aid. The ashing was performed, after a preliminary drying step atU50 C in a muffle furnace for 2 hours. To prevent the volatilization of selenium,nickel nitrate was used as a stabilizator aid.

The detection limit of the method: lOng / lOmg sample, dissolved in 500 L0,1 M nitric acid solution.

Ill EWA M. BEM: Env. Health Perspectives 37_, 183, 19-81

C2I1 EARL L. HENN: Anal. Chem. kj_ (3), U28, 1975

C3D TH.D. MARTIN, R.D. EDIGER: A. A. Newsletter 1*4. (5), 109,.1975

[In Analytical Methods Committee Analyst (London), lO t, 778, 1979

C5D D.C. REAMER, C. VELLON: Anal. Chem. 5_3, 1192, 1981

- 142 - 0

Application of the Inductively Coupled Plasma for the QuantitativeAnalysis of Geological and Related Materials

I.B. Brenner, I. Gal, H. Eldad, L. Halicz and D. HofferGeochemistry Division, Geological Survey of Israel

The production of industrial materials, commencing with exploration

of potential sources of raw materials, their beneficiation and processing

poses numerous analytical challenges.

A description is given of the use of an inductively coupled plasma

multichannel vacuum spectrometer in the quantitative analysis of geological

(phosphates, clays and carbonates) and related industrial raw materials

(cements, fly ash and silicate refractories) for their major and minor

element composition (Si, Mg, Ca, Al, Fe, Mn, Ti, P and S).

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES),

a relatively new analytical tool posseses unique physical properties

which in practice are expressed as high precision, wide linear dynamic

range of the calibration curves, relative freedom from matrix effects

and high powers of detection.

Solid samples are dissolved by a variety of conventional acid

and fusion dissolution methods and the sample aerosols generated by a

pneumatic nebulizer are injected into the interior of the high temperature

plasma (10000°). The radiation is directed into a multi-channel

vacuum spectrometer and the elements determined simultaneously under

a single stt of operating conditions.

The accuracy and precision achieved in routine analysis are

comparable, or superior to those achieved by atomic absorption and

X-ray fluorescence spectrometry.

- 143 -

Analysis of Sorbitan Fatty Acids Esters By HPLC

By: N. Garti, E. Wellner, A. Aserin and S. Sarig

Casali Institute of Applied Chemistry

School of Applied Science and Technology

The Hebrew University of Jerusalem

Jerusalem, 91904.

A need for analysis of food emulsifiers arises at several stages of

their production and use, e.g. for production control, for comparison

of emulsifiers purchased from differnt suppliers and for the detection

of the type of emulsifiers used in a competitor's food product.

The litterature reports separation identification and quantitative

estimation of the mono-, di- and tri-fatty acid esters of sorbitol and

of its anhydrides. Most techniques are based on pretrestment

(hydrolysis) of the emulsifiers, derivatization aad use of GLC as the

essential quantitative method for analysis. These techniques are tedious,

time consuming and not accurate.

We propose a new method to separate, identify and analyse the sorbitan

esters of fatty acids by HPLC technique. No derivatizatioii is^,necessary.

Using U.V. detector, without a need of gradient of eluents and in a short

period of time (13 min) mono-, di- and triesters of stearic, palmitic,

oleic, lauric, isostearic and sesquioleic acid of several suppliers have

been analysed and compared.

- 144 - 0

DISTRIBUTED LOCAL AREA NETWORKS FOR CHROHATOGRAPHY LABORATORIES

D. Ord and J. Fremajer

R & D Division, Spectra Physics, Darmstadt, W. Germany

The continuing increased demand for analytical services has lead tomajor advances in instrument automation,.particularly in the chromato-graphy laboratory. The speed with which analytical data can be generatedand therefore the quantity produced has lead to a greater need forlaboratory management facilities such as statistical analysis, reportcorrelation and sample tracking. Traditionally, this has been achievedon a larger laboratory computer with the capability to support manyinstruments and include customized reporting, centralised control andfree programmability. However, as with any system based on a centra-lised computer, any failure can have dire effects on the work of thelaboratory.

With this problem in mind, an alternative approach is presented based ona distributed instrument network. Such an approach provides each stationin the chromatography laboratory with independent intelligence and freeprogrammability, but has the benefit of centralised control, remotemonitory and the benfitof mini-computers for laboratory management re-quirements.

The strategy for inter and tntra instrument communication will be dis-cussed together with its application and impact on the individual chro-matography station and its extension in a local area network.

- 145 - 0

RECENT DEVELOPMENT IN HIGH RESOLUTION CHROMATOGRAPHY: ULTRA PERFORMANCEFUSED SILICA CAPILLARY COLUMNS AND LIQUID ON-COLUMN SAMPLING

Piet Van HoutHewlett-Packard CompanyHewlett-Packard Strasse 17517 Waldbronn 2West Germany

Fused silica capillary columns were for the first time introduced in 1979 at theHinderlang Capillary Symposium by Hewlett-Packard. Two outstanding characteristics of thesecolumns were immediately recognised. Their flexibility, allowing also unexperienced usersto handle the column with virtually no risk of breakage, and, their inherently high inertnessdue to a well characterized, very pure (less than 1 ppm contaminants) silicum oxide surface.This last phenomenon led to the application of capillary chromatography in areas where,up to then, coventional glass capillary analyses either had failed or only could be carriedout with great difficulty.

Due to the low surface energy of the pure fused silica a polar liquid phase will not easilyform a uniform liquid layer on the surface, which is the reason for the limited availabilityof phases on fused silica. Recent developments among others crosslinked of the phase, haveconsiderably improved that situation.

Crosslinking phases have several additional advantages: it enables the column to be rinsedwith solvents in order to remove deposits, it allows the use of more aggressive solvents,and it increases the temperature stability of the column.

Hewlett-Packard has developed the technique of deactivating, coating and crosslinking tosuch a stage, that for certain phases "ultra columns" are in existance which, next to ahigh chromatographic performance exhibit from column to column retention index variation ofless than +-0.5 units and capacity ratio variations of less than +-0.2 units.

The technique of introducing a sample directly on the capillary column without priorevaporation will be discussed. This a "Liquid On-Column Injection" offers a number ofadvantages, wich briefly can be summarized as:- Elimination of sample discrimination because of syringe effects,- Elimination of sample decomposition due to either thermal or catalytic (i.e. metalsyringe needle) effects - excellent quantification.

During the lecture a dedicated injector will be presented which, in addition to theseadvantages, can be easily implemented into routine laboratory practice. Characteristics andoperational aspects of the system will be discussed and illustrated with application examples.

- 146 - 0

DIODE ARRAY TECHNOLOGY APPLICATIONS IN UV/VIS SPECTROPHOTOMETRY AND

IN LC/UV DETECTION

Daniel FusterSID SpecialistHewlett-PackardPOB-CH 1217Meyrin 2.Geneva, Switzerland

Recent progress in diode array detection, computer control, optical componentsare discussed. They lead to a new generation of UV/VIS Spectrcphotometers andLC/UV detectors, wich are capable of acquiring, in parallel, all wavelengths ofthe range, and void the traditional serial access obtained by mechanical scanning.

Numerous applications in the pharmaceutical and biomedical fields are presented.

By permitting spectra to be measured within a few hundred milliseconds only,this technique makes information much more rapidly available and more readilyexplotable by such techniques as deconvolution.

In addition it allows identification and quantification in many cases wheretraditional spectrophotometers or detectors are limited by their unsufficient speed.

rTEACHING CHEMISTRY

- 147 -

"Turning Water into Wine": Student Difficulties

in Solving Problems

J. Dudley Herron

Purdue University,

Indiana, U.S.A.

Abstract

The audience will participate by solving a simple problem. Using

this problem as an example, Prof. Herron I'ill discuss various

difficulties that students encounter in beginning chemistry.

J- 148 - 0

THE MODERN LIFE - CHALLENGE AND MOTIVATION FOR STUDYINGCHEMISTRY

EXAMPLE - NUCLEAR CHEMISTRY

I. Maor

Department of Education in Technology § ScienceTechnion, Israel Institute of Technology, Haifa.

The study of chemistry has lost its "romantic image" and is now consi-dered by most students to be a dull, difficult, illogical and uninterestingsubject (1). Modernization of the subject could contribute very much toturn it again into one of the most fascinating subjects studied in highschool and later at universities. As an example, a proposal of a newapproach to teaching nuclear chemistry is presented.

The motivation for the studying of this important subject is obtainedby combining the frequent discussion of topics like nuclear energy andweapons by the media with the presentation of some of the most modernresearch, performed nowadays in the field. As a pre-requisite only abasic knowledge of the periodic table and atomic structure is required.

The starting point should be the extension of the periodic table byproducing heavier nuclei, thus leading to unstable artificial elements(up to Z =*vlO3). Radioactivity, which may be illustrated as the solutionof nature to the instability of nuclei is introduced as a practical instru-ment for atomic age determination, followed by quantitative concepts likehalf lifetime and isotopes. The shell model and magic numbers should bepresented stressing the analogy to the periodic table, leading to new pre-dictions of an additional "stability island" around Z = 114, N = 184,which is now experimentally looked for (2).

To show how such elements can be produced, the nuclear accelarator andreactor are introduced. Fission and fusion processes leading to chainreactions which release a huge amount of energy are the basis for the dis-cussion of energy control problems. Finally, both safety considerationsand advantages of nuclear energy are discussed in detail.

References

1. R.G. Silberman, Journal of Chemical Education, 56, 1036, (1981).

2. G.I. Seaborg, W. Loveland, D.J. Morrisey, Science, 203, 711, (1979).

- 149 - 0

nmrnnn nyiynn frta pmm

,TIIN

. >nnnn pneia mrm nmrnaii roiyan KB>IJ DISOI mrn - :moa, (m*no»n mawa p!>n m ononw) n m t n a nDiya ni!? - :

pne>onpnunn t>j) , n n n i

12 njpnvna ,

pnwan - -.

3 -- :pnwan

11*1*1 An

raiO'OID n O'DID

J)7T— • •

JTJ '

;I7T J71'

ti>iirna

pnwan - :60-n nntin

QIU nnnn (4) nou'nn Q>pne»a

n ia i ,oioKnnianoa rn»a»3 n n u t i

vmtwonb *mib pnwan - D ' j i i m Bitaw >ID Tin o>pne>a Q>Tat>nne»

pnwa. (3 ) , (2 ) , ( i ),nr «jon pnwa

Dim pnwan .1m n i f t m ,>aiii)pi»K

pnwani iriNa .2

"D»iin"n nK *>TD3 iaa o^a^oa . nnunan wiyan oy waao»aiD niDni njan nnt* DnwoKa m^>yani n»aan

on>at>nn nt pnwa^ .3wiaa n a Tin

(1) Deutsch and Krauss (1960) "The Effect of Threat on interpersonalbargaining11 in J. of Abnormal and Social Psychology, 1960, 61 183

1960, 6^ 218.

(2) Boocock and Coleman (1968) "Simulation Games in Learning" Fage Publication,Beverly Hills, California.

(3) Tansey and Derick (1969) "Simulation and Gaming in Education" London,Methuem Educational.

(4) las*! 113a nNinnn ib-ua nil "n -

- 150 - 0

maim ,o>!>E>-?n oiny »"y n ^ n - ^ i n nan

nannn

nwain

nnnn n'O'D fiann !>D nnw "nrsnn" nnaaa .nn>n>3 n o u n " owa KIP^ maynn

n ptvonb n

- 151 -

,7N'3A * I I N I 'ax-ia nn , ' T I N njn

.nuim ,y"M7 insm inn .D'yinn nNim7 np7nnn

Nian n'33n mn73 ' T nn-oi . ( i ) np'P'sn ny ai7'eu 7Nie"a o-"3'an na'ona mn73.ininn 70 'p'p7nn njarrti n3inn np7a3i nA*in nae» , (2) "-minn man" - D"7|7'p»9n

, (3) " m a m n n )/H n77iD"»nn" n'33nn 7w nniAona minn naan nainn namin 'n" n paV n'n»3n p a ippn TIN wxin , n m p ' n 70 n ' m n n n n7aua mpnnn

yinn 'Nivn ai7"»u' .n*n'3n ' N W U 7W anKnn7 D'xmjn 7nmn T I P ' H 'AK/IO TIN DA a7i«mayin nNiina nuVfn N'n rpa ' imuj 'Ni i j\v>xn :(4) D7iya a&yin I\H qj7»n ma m

n7a'i7n;n73'Nn nf'An 7e» n'ni'iynian .o^a 'an na'uni ' i i o ' n ISDH n'a 7'Aa.(5) n'313'nn nnaDa D'an n'inNna npD3

nwynV I N ,nTa HT D'aiVw DPCD o " j ' a n na'una yaon ' y m nN n m n 7 n"uinj 'nan .n'n'3-np'D'Da ni'3Dnn va> n:7a niN'n 7c i i ' i y n n m 'n ay . n a a a n"»Ai7T»an

rmynap TDa jiNuaDQ D"»'7p'D'an D'yinn v a 7 D"nn ' y in t*a nu 'nnn nvap ,TD7nn 7w7 T - 7 y nyyann inNTin IE»N , ( ' "773 ym11

I N ) "yao" Dt»a yixpn y a m 'n- 'T niipaa niyemnp'D'aai n'Ai7i 'aa T'n7nn BAOJ 'V nn'Dn 7nn .unuona A i7Ta 7 7 3 - i n a , m i n I H I N

. " nipaa RT D'&innn n'n'Dn ' t i i i 'V .773 mn73 HJ 'N n'n'Dnm ny»a ,7133a

D'7'An rniua npaAnni mmynn y7na ma" jynnn ' 3 D'Tyn (6) D'an D'ipnn'aA7 mil? H I D I I N mjVwn ni'n7 m'iB»y Q"3'an na^un n7nna Q'y7nn nNTin7Bimiynn »TN ,na7n -p D nN DN .137 layn *IN ' 7 I N I nai'Vyn na'una 7in'7n

na»una yaun 'y70 nNTin I B I N DNH :HNan n7N»n773a

•n 7i73n i a « nsina. itswi f i977-a ^nniy 7a7E>-ai ipnn niADna np7a3 I Tn m 3 7n'7y nnponn ,n3i'7yn na'unn lay VN Q"3 'an na'unn n7n73n nNima

n; a7E»a . ' u - ' n nm'3a D'7'D7n 1100-3 p7n 1703 law iiPNin ipnnn a7B» 7N*n7n Vy •Q"»7ip'i!>n naiyn Vy 7iny7i ,y7na D'7'n7n 7B» ni3"3ynn 'ninn nsn v ' ^ 7 1 niD37nnny '317NK» i i i A ' m ni3"3ynn inan .n'n*3n 7 in '7 '373 Dn'ni37yn D71D nN n'yaipn

.ipnn '733 u»nu»

in'3 17 Aii'Dnn n3if i3iNa ni7y7n mysin D'AiiDn D'7'n7n ' 3 0'7yn D " U D ' D O D D'nin'3n i ' n ' 3 mysin ,7wn7 ,-\O ."D7'D7p"n n'mnnV y7nn

7y VH nn»n "niaiainn VN n m c n n " n'33nn nN nn7 NVW n7N :7i33 ninn7,nniN nn7«> n*7N ; (?n 'Ai7 i 'a ?yao) nnN nt/p'n 7N3 ni'y7nn my3inn 737

n7n'3n n '3 'Na ' f i p n .nniN nn1? iau» 131N7 DNnna - np'D'sm n'n'3n nN 7n'n'7'nVnE' nyB»a» 13a ' i u ' a ' T 7 Na (n7Ai7i'ann 7133a) onVmi m m '7ya c m n n a np'D'srn

."n 'n '3 N7 I N ,yao i37n7" pm'3a A"nDn7 D'ai D'Pi3 ."n 'n 'a" inmv yixpn7 on"nn7

A1N77 i n x n 7y , i n " n p a ,my7axn7y - 137 laym ,D7737an na7ona yawn 7y7n nNiin niAona Diaa n7n73m 773a

H7n73 :DnB»a D7Nl!»137

.i"7Bm ,D77B»n7 ,n773B/ m n n n ,D77in77T3inn ,ma inm i i3 7 nn 7iB»n ,~>znnn ruza , ( a 7 3 i i y ) , .3 ,T3i iNi , . i , 7 ay - ia .2

ni733n7 T3inn ^rnsnsinn bn nmwrm , . 7 , I I 7 P I , .n , 7 T I N , .3 . T B I I N .3

,n"7K»n ,n3pinn 7 I D 7 3 m n n n ,y7n*7 i n y i ]i3n ,a7y7nn nNiin7 np7nnm ,mainm i i3 7nnHaggis, S . , and Adey, P., "A review of integrated science education worldwide", .*»in New trends in integrated science teaching, Vol. V, 35-39, Paris: Unesco, 1979.Brown, S.A., "A review of the meaning of , and arguments for , integated science", .5Studies in Science Education, 4, 31-62, 1977.Ormerod, M.B., and Duckworth, F . , Pupils attitudes to science, Slough (England): .6NFFrf, 1975.

Lawson, A.E. The development and validation of a classroom test of formalreasoning. Journal of Research in Science Teaching, 1978, L5_, 11-24.

Longeot, F. Analyze statistique de trois tests genetiques collectifs.Bulletin de l'Institut National d*Etudes 1965, 2£, 219-237.

Tisher, R.P. and Dale, L.G. Understanding in Science Test, Victoria,Australian Council for Educational Research, 1975.

I

iI

i

i

i

ii

i

TO: VICE- PRESIDENT, CORPORATE PLANNING/BUSINESS DEVELOPMENT

FROM: LEO HEPNER AND CELIA MALE

SUBJECT: CAN YOU REALLY AFFORD TO BASE YOUR FERMENTATION

BIOTECHNOLOGY/EXPANSION, DIVERSIFICATION AND

RESEARCH PROGRAMME ON CONFUSING TRADE STATISTICS

AND SENSATIONAL PRESS RELEASES?

FOR 12 YEARS WE HAVE MONITORED THE FERMENTATION/BIOTECHNOLOGY AREA

TO DETERMINE PRODUCTION, FERMENTATION CAPACITY, PRICE TRENDS AND FUTURE DEMANDS.

WE HAVE RECENTLY COMPLETED SEVERAL SURVEYS ON 'PRODUCT OPPORTUNITIES IN FERMENTATION,

1981-85'

THESE PROVIDE ESSENTIAL INFORMATION FOR PEOPLE LIKE YOURSELF CONCERNED WITH

DEVELOPING A CORPORATE STRATEGY FOR THIS AREA. WE HAVE ASSESSED PRODUCTION

IN TONNAGE, MARKET SHARES, FERMENTATION CAPACITY OF MAJOR AND MINOR COMPANIES,

AND GROWTH PROSPECTS FOR THE FOLLOWING CATEGORIES:

1.

2.

3.

4.

5.

6.

ORGANIC ACIDS

ANTIBIOTICS (HUMAND AND ANIMAL)

ENZYMES

POLYSACCHARIDES

AMINO ACIDS, (PHARMACEUTICAL, FOOD AND FEED GRADE)

VITAMINS, STEROIDS AND ALKALOIDS.

WE HAVE PROFILED THE ACTIVITIES OF OVER 125 COMPANIES INVOLVED IN THESE

PRODUCT SECTORS, WORLDWIDE.

WE FEEL THAT THIS SURVEY COULD BE THE MISSING LINK IN YOUR CORPORATE

PLANNING AND WILL GLADLY SEND YOU FURTHER INFORMATION.

OUR ADDRESS: L. HEPNER AND ASSOCIATES

TAVISTOCKHOUSE NORTH

TAVISTOCK SQUARE

LONDON WC1 ENGLAND

TEL: 01-387-2295

OR CONTACT OUR LOCAL REPRESENTATIVE MR. MARTIN STRAUSS

LANDSEAS ISRAEL

TEL: 299-091-2-3-4

TELEX: 342216

P.O.B. 23011 - TEL-AVIV.

i

\

Hewlett-PackardAnalytical Instruments

HEWLETTPACKARD

Liquid ChromatographsLaboratory Automation Systems

Gas ChromatographsReporting Integrators

GC/Mass SpectrometersUV/Visible Spectrophotometers

Represented by

EldanEL.DAIM ELECTRONIC INSTRUMENT CO. LTD.IS OHQLIAV STREET . JERUSALEM 94467 ISRA6U

P.OB. 137C. JERUSALEM 31Q12