Upload
cullen-harrower
View
214
Download
0
Embed Size (px)
Citation preview
1
Unit 4 + 5 (2008- syllabus)
Paper details
• U44 Exam 1h 40m. 3 sections. (90 mks??). Section A,B & C
• A = multiple choice (objective Q's)
• B = Short answers & extended Q's inc. analysis and evaluation of practical work
• C = Data questions and use of data
Paper details• U5 Exam 1h 40m. 90 marks. Section A,B & C
• A = multiple choice (objective Q's)• B = Short answers & extended Q's inc. analysis and evaluation of
practical work• C = Questions requiring extended answers. 'Senarios' may be given
and students expected to answer Q's based on the chemistry presented. “Contemporary context questions”.“Contemporary context questions”.
• Sections B & C will be where a students can show their full ability. Knowledge from previous units required.
• QWC considered. Data book can be used.
Unit 2.10(Organic I)
Reaction summary
Followed by Unit 4.8 Further organic chemistry (Organic II)
Mike Allan Hamzah. INTEC 2010. My information here is free of all restrictions
Recall of function groups…Recall of function groups…Functional groups.• Atoms or sequences of atoms causing
deviations in electron density to that of its hydrocarbon equivalent. E.g ethanol & ethane
(C=C, -X, -OH, -COOH <<< Unit 2.10)
CMgBr, -COOH, COOR, CMgBr, -COOH, COOR, CHO, COCHO, CO, -NH, -NH22,,
-NHR, -NR-NHR, -NR22, -COX, CONR, -COX, CONR22, CN,, CN,
Ether: REther: R33C-O-CRC-O-CR33(R=H or carbon)(R=H or carbon)
Unit 2.10 summary
Alkanes
CO2 + H2O
As fuelsAs fuels
Halogenoalkanes
FunctionalizationFunctionalizationvia halogen radicalsvia halogen radicals(need X(need X22 and U.V.) and U.V.)
PyrolysisPyrolysis(thermal cracking)(thermal cracking)not on syallabusnot on syallabus
Alkanesof differenttypes andalkenes
Alkenes
KMnOKMnO44(aq)(aq)
& OH& OH--(aq)(aq)
C=C
A diolA diol
C-C
HO OH
polymerizationpolymerization
C-C-C
poly(ethene) - PEpoly(ethene) - PEpoly(propene) – PPpoly(propene) – PPpoly(vinylchloride) - PVCpoly(vinylchloride) - PVCpoly(tetrafluoroethene) – PTFEpoly(tetrafluoroethene) – PTFE
HydrogenationHydrogenationHH22(g) + (g) +
Rayney nickelRayney nickel
AlkenesAlkenes
ADDITION REACTIONS !!!ADDITION REACTIONS !!!cis-cis- and and trans-trans- isomers possible isomers possible
due to restricted C=C bonddue to restricted C=C bond
PolymersPolymers
H X
HydrogenHydrogenhalogenationhalogenation
Use MarkovnikovUse MarkovnikovIf If unsymmetricalunsymmetrical
HalogenationHalogenation(X(X22))
C-C X X
C-X
Halogenoalkanes
C-NH2
KKCNCNRefluxReflux
under heatunder heat(ethanol solvent)(ethanol solvent)
Nucleophilic substitutionNucleophilic substitution
andand
Elimination reactionsElimination reactions
KOH(ethanolic)KOH(ethanolic)Reflux under heatReflux under heat
(dehydrohalogenation)(dehydrohalogenation)Elimination!Elimination!
C=C
C chainC chainextended !!!extended !!!
PolysubstitutionPolysubstitutionpossible. To 2possible. To 200 and 3 and 300 amine amine
C-C≡N
KOH(aq)KOH(aq)Reflux under heatReflux under heat
C-OH
Displaced XDisplaced X--
This can thereforeThis can thereforebe uses to testbe uses to test
for the (halogen)type of R-Xfor the (halogen)type of R-X
After reflux add HNOAfter reflux add HNO33 (aq) (aq)
THEN Ag(NO3)(aq)THEN Ag(NO3)(aq)
Excess c.NHExcess c.NH33
Reflux under heatReflux under heat
C-OH
Alcohols
NaX and c.HNaX and c.H22SOSO44
Reflux under heatReflux under heat
HalogenoalkaneHalogenoalkane(alkyl halide)(alkyl halide)
C-X
oxidationoxidation
C-O-Na+
KK22CrCr22OO77 (aq) + H (aq) + H22SOSO44(aq)(aq)
Distill for aldehydeDistill for aldehydeReflux for carbox. acid.Reflux for carbox. acid.
PClPCl55 / PCl / PCl33 / SOCl / SOCl22
2P + 3Br2P + 3Br22
2P + 3I2P + 3I22
Nucleophilic substitution, Nucleophilic substitution,
elimination, andelimination, and
oxidation reactionsoxidation reactions
Na(s)Na(s)c. Hc. H22SOSO44
170 170oo
(elimination)(elimination)
C=C sodium alkoxidesodium alkoxide
C
AldehydesAldehydes&&
ketonesketones
COOH
O
RR’
Carbox. acidsCarbox. acids
If aldehydeIf aldehyde
oxidationoxidationAlAl22OO33(s) 300(s) 300ooC C
andandPP44OO1010
can alsocan alsobe usedbe used
N.B. Initial alcoholN.B. Initial alcoholmust be drymust be dry
4.8 Further 4.8 Further OrganicOrganic
4.8 Further Organic4.8 Further Organic
enantiomers
4.8 Further Organic4.8 Further Organic4.8.1 Chirality4.8.1 Chirality a) recall the meaning of structural and a) recall the meaning of structural and E-ZE-Z isomerism (geometric/cis-trans isomerism) isomerism (geometric/cis-trans isomerism)
Zis is cis
BA
D G
E = trans
• Identify largest group by atomic number Identify largest group by atomic number (or mass) on one side of db (e.g A & B)(or mass) on one side of db (e.g A & B)
• Do the same on other sideDo the same on other side (D and G) (D and G)
• Atoms of greatest at# on same side of Atoms of greatest at# on same side of the db, then compound = the db, then compound = ZZ isomer. isomer.
4.8.1 Chirality4.8.1 Chirality b) demonstrate an understanding of the existence of optical b) demonstrate an understanding of the existence of optical isomerism resulting from chiral centre(s) in a molecule with isomerism resulting from chiral centre(s) in a molecule with asymmetricasymmetric carbon carbon atom(s) and understand optical isomers as object and non-superimposable atom(s) and understand optical isomers as object and non-superimposable mirror imagesmirror images
• Chiral = Chiral = nonnon superimposable on its mirror superimposable on its mirror image. A pair of enantiomers is the result.image. A pair of enantiomers is the result.
• Asymetric = no element of symmetry Asymetric = no element of symmetry (reflection, rotation, reflection & inversion)(reflection, rotation, reflection & inversion)
http://astrobiology.berkeley.edu/Mars101/definitions.htm
http://chemed.chem.purdue.edu/genchem/topicreview/bp/1organic/chirality.html
• A substance is optically active if it rotates the plane of polarisation of monochromatic plane polarised light (ppl). [ poppop of monomono pplppl ] ]
• One enantiomer will rotate light by some angle, say +x degrees, but the other enantiomer will rotate the plane of monochromatic ppl by the same magnitude but in the opposite direction, say –x degrees.
4.8.1 Chirality4.8.1 Chirality c) recall optical activity as the ability of a single optical isomer to c) recall optical activity as the ability of a single optical isomer to rotate the plane of polarization of plane-polarized monochromatic light in rotate the plane of polarization of plane-polarized monochromatic light in molecules containing a single chiral centre and understand the nature of a molecules containing a single chiral centre and understand the nature of a racemic mixtureracemic mixture
Huh?...Huh?...
http://www.denhartog-scientific.nl/Producten/Polarimeter/Polarisg[1].jpg
http://andromeda.rutgers.edu/~huskey/images/polarimeter.jpg
Huh?...Huh?...
• One sourceOne source of chirality (the property of being of chirality (the property of being chiral) is in aliphatics with chiral) is in aliphatics with 4 different gps on 4 different gps on the same Cthe same C atom… but 4 diff gps isn’t the atom… but 4 diff gps isn’t the only way u can get chiral molecules. E.g. only way u can get chiral molecules. E.g. DNA helix, spirenes…DNA helix, spirenes…
http://chemistry.umeche.maine.edu/CHY251/Chirality.gif
• Different optical isomers can have radically different BIOLOGICAL properties. Phys props (other than optical rotation) usually the same.
http://waynesword.palomar.edu/images/limonene.jpg
• Thalidomide – enantiomers showing different biological effects
4.8.1 Chirality4.8.1 Chirality d) use data on optical activity of reactants and d) use data on optical activity of reactants and products as evidence for proposed mechanisms, as in SN2 and products as evidence for proposed mechanisms, as in SN2 and SN1 and addition to carbonyl compounds.SN1 and addition to carbonyl compounds.
• SN2 (animation page) (OR video1 vid2) rxns involve inversion of centre of chiraity (stereocentre). Product is optically active – will cause plane of polarisation of monochromatic ppl to rotate. Transition state.Transition state.
SSN2N2
“Stereochemistry at a glance By Jason Eames, Josephine Peach. Google books P42
4.8.1 Chirality4.8.1 Chirality d) use data on optical activity of reactants and d) use data on optical activity of reactants and products as evidence for proposed mechanisms, as in SN2 and products as evidence for proposed mechanisms, as in SN2 and SN1 and addition to carbonyl compounds.SN1 and addition to carbonyl compounds.
• SN1 (animation page) rxns have the substrate give racemic mixtures (mixtures of both enantiomer products). Product mixture is optically inactive – no effect of plane of polarisation of monochromatic ppl. Carbocation intermediate (may rearrange).Carbocation intermediate (may rearrange).
“Mechanisms in organic reactions” By Richard A. Jackson.Google books P104
SSN1N1
• AldehydesAldehydes RCHO R can be H or hydrocarbon. Methanal, ethanal, propoanal… benzaldehyde
• KetonesKetones RCOR’ R cannot be H, must be hydrocarbon (no methanone or ethanone) propanone(acetone), cyclohexanone
4.8.2 4.8.2 Carbonyl compoundsCarbonyl compounds a) a) give examples of give examples of molecules that contain the aldehyde or ketone functional molecules that contain the aldehyde or ketone functional groupgroup
Ald’s and ket’s with larger more complicated perfumes and flavourings. VolatilityVolatility is important.
4.8.2 4.8.2 Carbonyl compoundsCarbonyl compounds b) e b) explain the physical xplain the physical properties of aldehydes and ketones relating this to the properties of aldehydes and ketones relating this to the lack of hydrogen bonding between molecules and their lack of hydrogen bonding between molecules and their solubility in water in terms of hydrogen bonding with the solubility in water in terms of hydrogen bonding with the waterwater
MethanalMethanal(polar)(polar)
gasgas
Propanone Propanone (polar)(polar)
Volatile Volatile liquidliquid
Can H bond with water.!! & both polar, so soluble in Can H bond with water.!! & both polar, so soluble in water up to a few C’s long.water up to a few C’s long.
Electron density maps Red = Electron density maps Red = --
Ethanal Ethanal (not shown)(not shown) is the first aldehyde to be liquid at RTP. is the first aldehyde to be liquid at RTP.
Bpt > corresponding alkanes, but < than corresponding alcohols.Bpt > corresponding alkanes, but < than corresponding alcohols.
http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ch17/figures/acetoneepot2.jpg
http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ch17/figures/methanalepot.jpg
Aldehydes ‘n KetonesAldehydes ‘n Ketones
..O
C
C
:
C
..O
H
C
:
C
ketonealdehyde
Aldehydes tend to be more reactive than ketones because, sterically, of the lack of extra alkyl chain
as present in ketones. Also the alkyl chain, by inductive effect (+I), releases e- density to carbonyl and lowering charge on carbonyl, delocalizing the
charge over the nearby area.
4.8.2 4.8.2 Carbonyl compoundsCarbonyl compounds c) describe and carry out, where appropriate, the reactions of carbonyl compounds. This will be limited to:
i. oxidation with Fehling’s or Benedict’s solution, Tollens’ reagent and acidified dichromate(VI) ions
ii. reduction with lithium tetrahydridoaluminate (lithium aluminium hydride) in dry ether
Aldehydes ‘n KetonesAldehydes ‘n Ketones
1O Alcohol
2O Alcohol
3O Alcohol
aldehyde
carboxylicacid
ketone
LiAlHLiAlH44 in dry etherin dry ether
(esters can be reduced too!!!)(esters can be reduced too!!!)
OXIDATIONOXIDATION
ReductionReduction
AlcoholsAlcohols CarbonylsCarbonyls Carbox. acidsCarbox. acids
NaBHNaBH44 (can be aq too!)(can be aq too!)
Aldehydes Aldehydes can
undergo oxidn and
Redn
Ketones Ketones undergo
Redn
Acts as if a source of HActs as if a source of H-- (a (a nucleophile)nucleophile)
Aldehydes can be oxidised by a number of compounds, some are employed as a TEST to TEST to discriminate aldehydes from ketonesdiscriminate aldehydes from ketones
1) Fehlings solution (Cu2+ complex)
2) Tollens reagent / test (ammoniacal silver nitrate – [Ag(NH3)2]+ complex
3) Acidified K2Cr2O7(aq) or acidified KMnO4(aq)
OXIDATIONOXIDATIONAldehydes ‘n KetonesAldehydes ‘n Ketones
Fehlings A is a solution of CuSO4(aq)
Fehlings B sodium tartrate solutionand NaOH
Both solutions mixed together toform the chelated Cu2+ after intitial Cu(OH)2 ppte seenby the bidentate tartrate ions surrounding the Cu2+
- deprotonation of hexaaqua ligand does not occur – tartrate is a stronger ligand.
Cu2+ only reacts in one way and that is to gain electrons! It causes the loss of e- from a different species is an O.A.
Aldehydes ‘n KetonesAldehydes ‘n Ketones
On heating (to inc. rate of rxn), a red Cu(I) oxide precipitate forms
1) Fehlings sol1) Fehlings solnn
AgNO3(aq) + few drops of NaOH(aq) Ag(OH)(s)
Add NH3(aq) until black ppte just dissolves.[Ag(NH3)2]+ forms {counter ion = - OH}
Aldehydes ‘n KetonesAldehydes ‘n Ketones
2) Tollens reagent2) Tollens reagent
Heat with aldehyde andAg(s) is deposited
on walls of glass container.A silver mirror is formed.
If solution or container is dirty grey / black Ag2O(s) ppte can form.
INTERVALINTERVAL
• In rxn with of cyanide anionscyanide anions with halogenoalkaneshalogenoalkanes,(nucleophilic substitution), X substitutes (leaves) with :C≡N, so simply use KCN in a mix of ethanol and water solvent and refluxing under heat.
• However in the addition reactions with carbonyls, nucleophilic additionnucleophilic addition takes place. HCN(a gas) adds rapdily to carbonyls,
• e.g ethanal + HCN(g) 2-hydroxypropanenitrile. CH3 CH(OH)-CN
• HCN made by adding dil H2SO4 with KCN(in excess to allow sufficient –’ve CN ions
4.8.2 4.8.2 Carbonyl compoundsCarbonyl compounds c) describe and carry out, where appropriate, the reactions of carbonyl compounds. This will be limited to:
iii. nucleophilic addition of HCN in the presence of KCN, using curly arrows, relevant lone pairs, dipoles and evidence of optical activity to show the mechanism
-
--
Aldehydes ‘n KetonesAldehydes ‘n Ketones
HCN H+ + -:CN⇁↼
• Alkaline conditions don’t allow for the protonation of the carbonyl gp but do give high (:CN)- concentration. A compromise of about pH 5 gives the best results. Animation page.
Aldehydes ‘n KetonesAldehydes ‘n Ketones
O
H
CH3C :CN
-O:
H
CH3C CN
-H+
OH
H
CH3C CN
A CYANOHYDRIN (an -hydroxy nitrile) is produced.These compounds are useful for (further) synthesis.
Q: State a property of cyanohydrins…Q: State a property of cyanohydrins…
• Alkaline conditions don’t allow for the protonation of the carbonyl gp but do give high (:CN)- concentration. A compromise of about pH 5 gives the best results. Animation page
Aldehydes ‘n KetonesAldehydes ‘n Ketones
O
H
CH3C :CN
-O:
H
CH3C CN
-H+
OH
H
CH3C CN
A CYANOHYDRIN (an -hydroxy nitrile) is produced.These compounds are useful for (further) synthesis.
(or H-CN)
(Generates H+)
*
Q: State a property of cyanohydrins…Q: State a property of cyanohydrins…
Aldehydes ‘n KetonesAldehydes ‘n Ketones
Nitriles (CYANOHYDRINs) can undergo hydrolysis reactions
OH
H
CH3C CN
OH
H
CH3C
O
OH
C
Dilute acid(H2SO4)
Heat underreflux
An hydroxyacid
Dilute NaOH can also be used. Heat under reflux but like base
hydrolysis of esters, the anion of the carboxylic acid will form!!!
Each hydrazine reacts with carbonyls to form a hydrazone. Hydrazine itself is very toxic and so is no
longer used. The dinitrophenyl version is employed instead.
Aldehydes ‘n KetonesAldehydes ‘n Ketones TESTTEST
SpecificSpecific for carbonyl…!!! for carbonyl…!!!
..N N
H
H
H
O2N
NO2
..
2,4-dinitrophenylhydrazine (2,4-dnp)
N N
H
H
H
H
....
hydrazine
The 2,4-dnp test
This lone pair is the active one and attacks the carbonyl carbon
..N N
H
H
H
O2N
NO2
..
N N
H
H
O2N
NO2
..
N N
H
H
H
O2N
NO2
..+
H
Aldehydes ‘n KetonesAldehydes ‘n Ketones TESTTEST
The 2,4-dnp test
O
H
CH3C
(1)(2)
lp on N actsas a nucleophile
..O
HC
:
H3C
:-N & O undergo proton
exchange
..O
HC
:
H3C
N N
H
O2N
NO2
C
CH3
H
..ck
A
hyd
razo
ne
ckorange Yellow
ppte
(3)
(4)
(5)
(6)
(7)
++
http://www.chem.ucalgary.ca/courses/351/Carey/Ch17/ch17-3-3-2.html
48 propanal 14856 acetone 12663 2-methylpropanal 187(183)75 butanal 12380 2-butanone 11791 3-methylbutanal 12392 2-methylbutanal 120100 2-pentanone 143102 3-pentanone 156103 pentanal 107(98)115 4-methyl-2-pentanone 95128 5-hexen-2-one 1081294-methyl-3-penten-2-one 205131 cyclopentanone 146131hexanal 104(107)145 4-heptanone 75145 5-methyl-2-hexanone 95
Bp ofStartingCarbonylUnknown
mp of2,4-DNPDerivative
131 hexanal 104(107)145 4-heptanone 75145 5-methyl-2-hexanone 95146 2-heptanone 89147 3-heptanone 81153 heptanal 108156 cyclohexanone 162169 3-methylcyclohexanone 155173 2-octanone 58179 benzaldehyde (PhCHO) 237200 o-methylbenzaldehyde 194204 p-methylbenzaldehyde 34202 ethanoylbenzene 244216 1-phenyl-2-propanone 156217 (2-methylpropanoyl)benzene 163218 propanoylbenzene 191226 p-methylacetophenone 258232 butanoylbenzene 191235 4-phenyl-2-butanone 127248 p-methoxybenzaldehyde 253
mp of2,4-DNPDerivative
Bp ofStartingCarbonylUnknown
SomeSome aldehydes, aldehydes, some some ketones and ketones and somesome alcohols… alcohols…
Specific reaction…
Triiodomethane rxn
(iodoform precipitation reaction)DOES NOT:a) Identify carbonyls from alcohols
b) Identify aldehydes from ketones
Triiodomethane rxn(iodoform precipitation reaction)
So what does it do?
a) Tests for methyl carbonylsmethyl carbonyls
b) Tests for methyl alcoholswhich can be oxidised to methyl carbonyls.
Note: cannot be tertiary alcohols in that case!
C
H
H
H
CO
Acyl group(abbreviation Ac)
C
H
H
H
C
OH
H
Triiodomethane rxn(iodoform precipitation reaction)
Required reagents:
• I2(aq) + NaOH(aq)
or
• KI(aq) + NaClO(aq)(ClO- is an O.A. and ‘dynamically
converts I- into I2 )
C
H
H
H
CO
Acyl group(abbreviation Ac)
C
H
H
H
C
OH
HAll these alpha H’sget replaced by I
Triiodomethane rxn(iodoform precipitation reaction)
C
I
I
I
CO Forms rapidly
C
I
I
I
H
Triiodomethane (ioodoform), an unpolar SOLID, ends up breaking away.
(appropriate alcohol versions get oxidised to this acyl gp first)
Carboxylate anion on
other fragment
dissolves in soln
Triiodomethane rxn(iodoform precipitation reaction)
The triiodomethane smells like antiseptic or a dry cleaners (dry cleaners used to use trichloromethane – a compound (probably toxic: carconogenic, tetragenic and mutagenic – not that nice really and it’s said to destroy ozone.)
Always better to ID iodoform from the ppte rather than the smell !!!
Test may be problematical – my guess [I2] is too low in the ‘bench’ test solution.
Further Organic revision.Source: http://www.rod.beavon.clara.net/Problem 1.
Compound A, C3H80, gives steamy fumes when reacted with phosphorus pentachloride. On oxidation with acidified potassium dichromate solution A gives B, C3H60. This, with a source of H3C:- nucleophile, gives C upon addition of acid, C4H10O. C does not react with acidified potassium dichromate solution. Treatment of C with excess hot concentrated sulphuric acid gives D, C4H8, which on reaction with hydrogen bromide gives mainly 2-bromo-2-methylpropane. Find the structures of A to D, giving reasons and equations for the reactions which occur.
Further Organic revision.Source: http://www.rod.beavon.clara.net/Problem 2.
Benzene C6H6 and chloromethane CH3Cl react in the presence of aluminium chloride to give A, C7H8. A reacts with chlorine in sunlight to give B, C7H7Cl, which reacts with aqueous sodium hydroxide to give C, C7H8O. Mild oxidation of C gives D, C7H6O, which with 2,4-dinitrophenylhydrazine gives an orange precipitate. Further oxidation of D gives E, C7H6O2, which can also be produced from A by vigorous oxidation with alkaline potassium manganate(VII) solution.
The reaction of B with potassium cyanide under suitable conditions gives F, C8H7N, which in turn can be reduced to G, C8H11N.Identify the substances A to G, giving reasons for your choice and writing equations for the reactions that occur. Write the mechanism for the reaction between benzene and chloromethane. Suggest another series of reactions by means of which you could convert F to G.
4.8.3. Carboxylic acids • a. give some examples of molecules that contain the carboxylic acid
functional group• b. explain the physical properties of carboxylic acids in relation to
their boiling temperatures and solubility due to hydrogen bonding
Palmitic acid C16 H32 O2 benzoic acid C16 H32 O2
R-COOH&
bptCarboxylic acids have much higher boiling points than hydrocarbons, alcohols, ethers, aldehydes, or ketones of similar molecular weight. Even the simplest carboxylic acid, formic acid, boils at 101 °Cformic acid, boils at 101 °C which is considerably higher than the boiling point of ethanol (ethyl alcohol), C2H5OH, which boils at 78.5 °C, although the two have nearly identical molecular weights. The difference is that two molecules of a carboxylic acid form two hydrogen bonds with each other (two alcohol molecules can only form one). Thus, carboxylic acids exist as dimers (pairs of molecules), not only in the liquid state but even to some extent in the gaseous state. Therefore, boiling a carboxylic acid requires the addition of more heat than boiling the corresponding alcohol, because (1) if the dimer persists in the gaseous state, the molecular weight is in effect doubled; and, (2) if the dimer is broken upon boiling, extra energy is required to break the two hydrogen bonds. Carboxylic acids with higher molecular weights are solids at room temperature (e.g., benzoic and palmitic acids). Virtually all salts of carboxylic acids are solids at room temperature, as can be expected for ionic compounds.
http://www.britannica.com/EBchecked/topic/95261/carboxylic-acid/277734/Boiling-point
Name Formula Melting Point (oC) Boiling Point (oC)
formic HCOOH 8 100.5
acetic CH3COOH 16.6 118
propionic CH3CH2COOH -22 141
butyric CH3(CH2)2COOH -6 164
valeric CH3(CH2)3COOH -34 187
caproic CH3(CH2)4COOH -3 205
lauric CH3(CH2)10COOH 44 225
myristic CH3(CH2)12COOH 54 251
palmitic CH3(CH2)14COOH 63 269
stearic CH3(CH2)16COOH 70 287
oleic cis-9-Octadecenoic 16 223
cyclohexanecarboxylic cyclo-C6H11COOH 31 233
phenylacetic C6H5CH2COOH 77 266
benzoic C6H5COOH 122 250
o-toluic o-CH3C6H4COOH 106 259
m-toluic m-CH3C6H4COOH 112 263
p-toluic p-CH3C6H4COOH 180 275
http://wwwchem.csustan.edu/CHEM3022/Table_CbxlcAcid.htm
A look at the COOHA look at the COOHfunctional groupfunctional group
O
O
C
H
Because both functional Because both functional groups are on the groups are on the same same
carboncarbon, each group strongly , each group strongly affects the properties of the affects the properties of the other group, therefore other group, therefore each each
part produces: a unique whole.part produces: a unique whole. So do So do NOTNOT consider the COOH consider the COOH group as showing properties of group as showing properties of
alcohol or of carbonyls.alcohol or of carbonyls.
carbonyl
alcohol
At first sight…At first sight…
c. describe the preparation of carboxylic acids to include oxidation of alcohols and carbonyl compounds and the hydrolysis of nitrilesd. describe and carry out, where appropriate, the reactions of carboxylic acids. This will be limited to:i. reduction with lithium tetrahydridoaluminate (lithium aluminium hydride) in dry ether (ethoxyethane)ii. neutralization to produce salts, eg to determine the amount of citric acid in fruitiii. phosphorus(V) chloride (phosphorus pentachloride) iv. reactions with alcohols in the presence of an acid catalyst, eg the preparation of ethyl ethanoate as a solvent or as pineapple flavouring.
KK22CrCr22OO77 (aq) (aq)
++ HCl (aq) HCl (aq)
Unit 4.8.3 Carboxylic acidsUnit 4.8.3 Carboxylic acids
11oo alcohols alcohols
O
O
C
H
aldehydesaldehydes
KK22CrCr22OO77 (aq) (aq)
++ HCl (aq) HCl (aq)
GrignardsGrignards1)1) COCO22
2)2) HCl (aq)HCl (aq)
Acid halidesAcid halidesHH22O (l)O (l)
EstersEsters
( Inc. polyesters )( Inc. polyesters )
Hydrolysis ofHydrolysis ofamides andamides and
acidic workupacidic workup
PClPCl55
AcidAcidhalideshalides
1O Alcohol
2O Alcohol
3O Alcohol
aldehyde
carboxylicacid
ketone
LiAlHLiAlH44 in dry ether in dry ether
(esters can be reduced too!!!)(esters can be reduced too!!!)
OXIDATIONReductionReduction
AlcoholsAlcohols CarbonylsCarbonyls Carbox. acidsCarbox. acids
NaBHNaBH44 (can be aq too!) (can be aq too!)
Memory aid.Memory aid.AlcoholsAlcohols
and related and related compoundscompounds
Carbox.acids
http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ref/ch19reactioncarboxylicacids.html
Nitriles
http://www.chem.uic.edu/web1/OCOL-II/WIN/CH21/RXNS.HTM
Acidchlorides
http://users.ox.ac.uk/~mwalter/web_05/year1/year1_notes/carbonyl_chemistry/acid_chlorides.shtml
Fatty acids
http://www.hidden-diabetes-cures.com/fats-and-oils.htm
http://www.rsc.org/images/44---feature-fat-structure_tcm18-34671.jpg
http://www.raw-milk-facts.com/images/FatTrio.gif
Margarine
Margarine (?)
• Unsaturated oil + H2(g) -> saturated fat
• Add vitamins, colour…http://www.rsc.org/images/Fig2_pp109_Hargreaves_July09_tcm18-154953.jpg
http://www.quitehealthy.com/nutrition-facts/food-labels/label046131.gif
Soap:
Where you getfatty acids, youcan get esters!
Esters Production of Biodiesel (esters) and base hydrolysis of esters to Make Soap
Transesterification - BoidieselTransesterification - Boidiesel
TransesterificationTransesterification
• Biodiesel.
TransesterificationTransesterification
http://ezbiodiesel.com/News.htm
http://scienceprofonline.googlepages.com/chemistryhelp-organicandinorganic