gNAMIBIA UNIVERSITYOF SCIENCE AND TECHNOLOGY

FACULTY OF HEALTH AND APPLIED SCIENCES

DEPARTMENTOF NATURALAND APPLIED SCIENCES

QUALIFICATION: BACHELOR OF SCIENCE HONOURS

QUALIFICATION CODE: O08BOSH LEVEL: 8

COURSE CODE: AOC811S COURSE NAME: ADVANCED ORGANIC CHEMISTRY

SESSION: JUNE 2018 PAPER: THEORY

DURATION: 4 HOURS TOTAL MARKS: 100

FIRST OPPORTUNITY EXAMINATION QUESTION PAPER

EXAMINER(S) DR. MARIUS MUTORWA

MOpDERATOR:

|

DR. RENATE HANS

INSTRUCTIONS Answer ONLYFIVE OF THESIX questions.

Write clearly and neatly.

Number the answersclearly

eePY

All written work must be donein blue or black ink and sketches can

be donein pencil

5. No books, notes and otheradditional aids are allowed

THIS QUESTION PAPER CONSISTS OF 11 PAGES

(Including this front page)

PERMISSIBLE MATERIALS

Non-programmable Calculators

ATTACHMENTS

Solvent Chart, IR Spectral Data, pKa Chart and Periodic Table

QUESTION1: [20]

Question type: Enolates and Other Carbon Nucleophiles

1.1) Draw the enolate intermediate and major product which is formed from each of the

following reactions. (6)

a)

PheMOO.Et (1) 1 equiv LINH2/NH,

CH2CO>Et (2) CHsgl

b)

=

PRCHCOZEt (1) 2 equiv LINHo/NHgCH2CO>Et (2) CHgl

PhGHGOsH (1) 2 equiv LINH./NH,

CH,CO,Et (2) CHa!

1.2) Write the structuresof all the possible enolates for each ketone. Indicate which you expect

to be favouredin a kinetically controlled deprotonation and which you would expectto be the

most stable. (6)

(a) CHs (b) CHO

| O

C(CHa)3 CH; CHs

1.3) Analyse the factors that you expect to control stereochemistry of the following reactions and

draw the expected major products. Clearly indicate the configuration ofthe new stereochemical

centre created uponalkylation. (8)

(a)PRON 0 9 1) LDAICHs| by PRs 4) LoWHMPA

2) LDA/CH»=CHCH,Br J 2) CoHel

(c) (d) CHa .

(CH3)3CO,C, CH, 1) LIHMDS cH +9 1) LiHMDSN 76Dr/? ./202CoHs 2) CHsI

a 2) CHsI : 3H Ar

Ar = 4-methoxyphenyl

Page 2 of 11

QUESTION2: [20]Question type: Functional Group Interconversions

2.1) The following transformations involve the introduction or removalof a protecting group.

Indicate the conditions that would be appropriate to achieve eachof the transformations. (12)

or +

noHOEREEDer.

(CHs)2CH (CH,)CH

O(b) wCHg

«sCHCH,OH

““OH

CH;~O “OHSs CH;

(c) 9 °ox 9

HG CH2OCH,Ph TBDMSG CHz0CH,Ph

(d) i \ [\O_ 0 — 4O

CHSSCHCH=O CH;cre)

Page 3 of 11

2.2) Suggest a synthetic method to synthesis the material on the left from the material on the

right. No more than three steps should be required. (8)

(a) © CHPhCHCNHCHCH,CgHs pheHCOoHOCH; OCH3

(b) CHg

(CHs)eCHCHaCH=CHCHCH2CO2C2Hs => UV.

OCH,

(C) PhCH,S HO,

N*~ CO2CH3 => sco,

H|CH3C=O

QUESTION3: [20]

Question type: Mechanism and Pericyclic Reactions

3.1) Draw a stepwise-detailed reaction mechanism for the reaction below. Make sure to show

all the intermediates, products, charges and importantlone pairs. (12)

Note: fluorosulfonic acid (HO-SO2-F) is a strong acid, like sulfuric acid (HO-SO2-OH) but stronger.

H

“OH HSO;F‘VCH ——_> | / \

, CH

Page 4 of 11

3.2) The series of reactions below demonstrates a numberof pericyclic reactions. For each,

indicate the type of reaction and the numberof electrons involved. (8)

a.

O7 Oo

CfDzb.

OAc

on hv) + FT \ omc # Hwe \ /

Cr(CO)3

Cc.

SS hv S A —aes —_—> O| ——~ O

=

N No SN N=/y OO

d.

OO

Page 5 of 11

QUESTION4: [20]

Question type: Organometallic Compounds

4.1) Predict the product of each of the following reactions. Be sure to consider andspecify all

aspects of stereochemistry involved in the reaction. (12)

|DO n-BuLi CoHlap

ICHsCHs

Zn, TiCl,

(b) PhCO,CHg + CHgCHBr, - C49H120MEDA,25°C

Zn dustCc — eee O77.) = 7,0)(C) CH3(CH2),CH=O + BrCH,CO,Et benzene 1orl29V3

(d) (poner active Cd PhCOCI C,,H,,0

4.2) Each of the following compoundsgives a product in which one or morelithium atoms has

been introduced underthe specified conditions. Predict the structure of the lithiated product

on the basis of structural features knownto promotelithiation and/or stabilization oflithiated

species. Note the numberoflithium atoms introduced is equal to the numberof moles of

lithium reagent used in each case. (8)

O .

n-BuLi, —120°C || 2 n-BuLi(a) HC==CCO,CH, (b) NHCC(CHs)g

THF/pentane/ether oes ,

n-BuLi Ph H HR(Cc) (CHg)>cCH— OCH, (d) \ /

TMEDA,ether pS °-113°C‘on

Page 6 of 11

QUESTION5: [20]

Question type: Multi-step and Retrosynthesis

Show how you would synthesise the following compounds. Thestarting material needed to

synthesise compound(a) should consist of eight (8) carbon atomsor fewerandthestarting

material needed to synthesis compound(b) should consist of six (6) carbon atomsor fewer.

You mayuseany otherinorganic reagents and organic reagents that don’t get incorporated

into the final product such as LDA, Ph3P, PCC, DCC, TsCl, TBDMSCIetc. (20)

Oa) SS b) Eto

Stereoselectively O

O

QUESTION6: [20]

Question type: Spectroscopy

Deducethestructure of a compound with a molecular formula CgHi004 that exhibit the following

IR, 7H NMR and 73C NMR spectra.

%Transmittance

= ee LS ee eee ae Oe

4000 3500 3000 2500 2000 1500 1000

Wavenumber(cm7")

Page 7 of 11

Proton NMR

3 3Expansion \ s 3

IE JI 25 1 5 porn |= i ° d5.5 45ppm 1 |

h | __ shPEELPEY

10 9 8 t 6 5 4 3 2 | 0

Chemical Shift (ppm)

Carbon NMR

'

Solvent

eeeeOe

PTTprE er rT rt et

200 160 120 80 AO aChemical Shift (ppm}

THE END

GOODLUCK

Page 8 of 11

SOLVENT PHYSICAL PROPERTIES CHART

Solvent Density mp bp MW Polarity Water solub.

(g/ml) (°C) (°C) (g/mol) index (g/100g)Acetic acid 1.049 16.6 118.0 60.05 6.2 Miscible

Acetone 0.786 -94.3 56.3 58.08 5.1 Miscible

Acetonitrile 0.786 46.0 81.6 41.05 5.8 Miscible

Benzene 0.879 5.5 80.1 78.14 27 0.18

Carbontet. 1.594 -22.4 76.7 153.82 1.6 0.08

Chloroform 1.498 -63.7 61.7 112.56 41 0.795

Cyclohexane 0.779 6.6 80.7 84.16 0.2 <0.1

DCM 1.326 -96.7 39.8 84.93 3.4 1.32

Diethyl ether 0.713 -116.3 34.6 74.12 2.8 7.5

DMEF 0.944 -61.0 153.0 73.09 6.4 Miscible

DMSO 1.092 18.4 189.0 78.13 25.3

Ethanol 0.789 -114.1] 78.5 46.07 5.2 Miscible

Ethyl acetate 0.895 -83.6 77.0 88.11 4.4 8.7

Grease - - - - - -

Heptane 0.684 -90.6 98.0 100.20 QO 0.01

Hexane 0.659 -$5.0 69.0 86.18 0 0.014

HMPA 1.05 7.2 232.5 179.20 Miscible

Methanol 0.791 -98.0 64.6 32.04 5.1 Miscible

Pentane 0.626 -129.7 36.1 72.15 a 0.04

Petroleum ether 0.656 -40.0 30-60 - 0 -

2-Propanol 0.785 -88.5 82.4 88.15 3.9 Miscible

Pyridine 0.982 41.6 115.2 79.10 Miscible

Silicone grease - ~ - - : -

THF 0.886 -108.4 66.0 72.14 4 30

Toluene 0.867 -93.0 110.6 92.14 2.4 0.05

Triethylamine 0.728 -114.7 88.9 101.19 - 0.02

Water 0.998 0.0 100.0 18.02 = Miscible Important IR Absorptions

Bond type Approximate ¥ (cm) Intensity

O-H 3600-3200 strong, broad

N-H 3500-3200 medium

C-H ~3000

© Cs3-H 3000-2850 strong

° C.2-H 3150-3000 medium

© Csp-H 3300 medium

C=C 2250 medium

C=N 2250 medium

C=O 1800-1650 (often ~1700) strong

C=C 1650 medium

1600, 1500 mediumaE Page 9 of 11

conjugateacid

conjugatebase

sulfuric

acid

HaSO,

hydroiodie

acid

HI

hydrobromic

acid

HBr

hydrochloric

acid

carbocationsa, y—a

protonated

alcohol

it ve+

.;

Ohydroniumion

4)yoo

‘9H

nitric

acid

HNO;———*

NO;

hydrofluoric

acidhE

sO.

carboxylic

acidsJL

_H—

JL,—

oO

.

pKaChart ph

enols

-7

water

3primaryalcohols

alkynes

-1.7

hydrogen

1.3

Le

1WNN1oN1a‘amines

32

alkanes

4.8

hydrogencyanide

conjugatebase

'C=N:

9.1

H—-C=N

5——»

(cyanide)

15.7

(hydroxide)

“go

“:16

(alkoxides)

C=C:

26

(acetylide

anions)

CcC=c—-H——>

H—-H

—“——

:H_

(hydride)

35

ahs—ei

36(amide

bases)

aa™N

:~60

hydr

ogen

1 H1.0079

fith

ium

bery

lliu

m

34

LiBe

6.941

9.01

22

sodium

magnesium

1112

Na|Mg

22.990

24.3

05

pota

ssiu

mcalcium

K|C

a39.098

40.078

tubidium

stro

ntiu

m

3738

Rb

Sr

85.468

87.6

2

helium

He

4.00

26

boron

§ B 10.811

carbon

6 C 12.011

nitrogen

7 N 14.007

oxyg

en8 O 15.999

fluorine

9 F

18.998

neon

10 Ne

20.1

80

aluminium

13 Al 26.982

sili

con

Si 28.086

phosphorus

15 Pp

30.974

sulfur

16 S32.065

chiorine

17 Cl 35.453,

argon

Ar

39.948

scandium

21

Sc

44.956

tita

nium

Ti 47.867

vanadium

23 V 50.9

42

chromium

24

Cr

51.996

manganese

25

Nin

$4.938

2%27.

Fe

Co

55.845

58.9

33

nickel

copper

29

NiCu

58.6

9363

.546

zine

30

2n

65.39

gallium

31

Ga

69.723

germanium

32

Ge

72.61

arsenic

33

As

74.922

selenium

34

Se

78.96

bromine

35

Br

79.904

krypton

36

Kr

83.80

yttr

ium

39 Y 88.906

Zitconium

40

Zr

91.224

niob

ium

41 Nb

92.906

molybdenum

42

Mo

95.94

technetium

43

Tc

{98}

ruthenium

rhod

ium

44

45

Ru}

Rh

101.

07102.91

palladium

silver

47

Pd|Ag

106.42

107.87

Cd

112.41

indi

um

49 In 114.82

50 Sn

118.71

antimony

51 Sb

121.76

tedurium

52 Te

127.60

iodine

53

126.90

xenon

Xe

131.

29

caesium

barium

55

56

57-70

Cs|Ba|

*132.91

137.33

lutetium

71 Lu

174.

97

hafnium

72 Hf

178.49

tantalum

73 Ta

180.

95

tung

sten

74 W 183.84

rhenium

75

Re

186.21

osmium

iridium

7776

Os|

Ir190.23

192.

22

plat

inum

gold

79

PtAu

195.08

196.

97

mercury

80

Hg

206.

59

thallium

81 Tl 204.38

Pb

207.

2

bismuth

Bi 208.

98 p

olonium

84

Po

[209

]

asta

tine

85 At {210 r

adon

86 (222) f

rancium

fadium

8889-102

87 Fr

Ra|**

[222]

{226}

lawrencium

103

Lr

{262

} ru

lherfordium|

104

Rf [264]

dubn

ium

105

Db

[262]

seaborgium

106

Sg

[266]

bohr

ium

107

Bh

hass

ium

meit

neri

um

108

109

Hs

Mt

{269}

[268] un

unnilium

unununium

110

111

Uun/Uuu

(271

)(2

72) u

nunbium

112

Uub

[277]

*Lanthanide

series

**Actinide

seri

es

ununquadium

114

Uugq

{_{zsq]_]

lanthanum

57

La

138.

91

cerium

58 Ce

140.12

praseodymium

59 Pr 140.91

neodymium

60 Nd

144.

24

promethium

61

Pm

[145]

samarium

europium

62

63

Sm|

Eu

150.

36151.96

gado

lini

umte

rbiu

m

6465

Gd|

Tb

187.

25158.93

dysprosium

66 Dy 162.50

holm

ium

67 Ho

164.

93

“ee.Er

167.26

thulium

69

Tm

168.93

yiterbium

70 Yb

173.

04 ac

tinium

89

Ac

{227

) th

oriu

m

90 Th

222.

04 pr

otac

tini

um

91 Pa

231.04

uranium

92

238.03

neptunium

93

Np

{237]

plut

oniu

mamericium

95

Pu

|Am

[244

]243}

curium

berk

eliu

m

96

97

Cm|

Bk

[247

]{2

47]

ca

lifornium

98 Cf {251

] ei

nsteinium

99

Es

(252

)

ferm

ium

100

Fm

(2

57)

mend

elev

ium}

101

Md

[258]

nobelium

102

No

{259)

259)

Page11of

11