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NAMIBIA UNIVERSITYOF SCIENCE AND TECHNOLOGY

FACULTY OF HEALTH AND APPLIED SCIENCES

DEPARTMENT OF NATURAL AND APPLIED SCIENCES

QUALIFICATION: BACHELOR OF SCIENCE

QUALIFICATION CODE: 07BOSC LEVEL: 7

COURSE CODE: OCH701S COURSE NAME: ORGANIC CHEMISTRY 2

SESSION: JULY 2018 PAPER: THEORY ~

DURATION: 3 HOURS MARKS: 100

SUPPLEMENTARY / SECOND OPPORTUNITY EXAMINATION QUESTION PAPER

EXAMINER(S) DR. MARIUS MUTORWA

MODERATOR:

|

DR. RENATE HANS

INSTRUCTIONS

AnswerALL the questions.

Write clearly and neatly.

Numberthe answersclearly

PwMe

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

be donein pencil

5. No books, notes and other additional aids are allowed

THIS QUESTION PAPER CONSISTS OF 16 PAGES

(Including this front page)

PERMISSIBLE MATERIALS

Non-programmable Calculators

ATTACHMENTS

IR and *H NMRSpectral Data, pKa Chart and Periodic Table

SECTION A

QUESTION1: Multiple Choice Questions

e There are 30 multiple choice questionsin this section. Each question carries

2 marks.

e Answer ALL questions by selecting the letter of the correct answer.

e Choose the best possible answerfor each question, even if you think there is

another possible answerthatis not given.

1.1 What is the IUPAC nameforthe following compound?

O“

H

A. 1-isopropyl-4-cyclopentanol

B. 3-isopropyl-1-cyclopentanol

C. 1-isopropyl-3-cyclopentanol

D. 1-isopropyl-4-hydroxycyclopentane

E. None of the above

1.2 Predict the productfor the following reaction.

1. Hg(OAc), H,OoO

2. NaBH,

OH CH2OH

OH

I IlI i IV

A. |

B. Il

C. Ill

D. IV


[60]

[60]

of 16

1.3 The reaction between 2-methyl-2-pentanol and sulfuric acid to yield 2-methyl-2-pentene goes

via

A. Sn1 mechanism

B. Su2 mechanism

C. E1 mechanism

D. E2 mechanism


1.4 Which of the following compoundswill show two absorptions at 2600 cm™ and at

2700 cm*along with the carbonyl absorption?O oO O O

A

I~AHK ATK, nk

A.|

B. Il

C.lll

D. IV

E.V

1.5 Which of the following compoundswill have the lowest wavenumberfor carbonyl absorption?

O Cl | | ; , - )

1 Il I IV Vv

A. |

B. Il

C.Ill

D.IV

E.V

of 16

1.6 For the following reaction, which of the following is consistent with the IR spectrum of the

product?0

A. absorption at 2150 cm*™should disappear

B. absorption at 3300 cm? and 2150cm"™should disappear

C. absorption at 2250 cm? should disappear, new absorption at 3300 cm™should appear

D. absorption at 1650 cmshould disappear and absorption at 3300 cm™ should appear

E. absorption at 3300 cm™ and 2150cm* should disappear, a new absorption at 1720 cm+

should appear

1.7 Which of the following is true about the relationship between the energy gap (AE)

betweenthe spin states for a +H nucleus and the strength of the external magnetic field?.

A. they are inversely proportional

B. they are directly proportional

C. there is no relationship

D. the magneticfield is slightly less


1.8 Which of the followingis true about the location of signals ina +H NMRspectrum?

A. it indicates the numberof neighboring protons

B. it indicates the electronic environmentof neighboring protons

C. it indicates the numberofdifferent protons

D. it indicates the electronic environmentof absorbing protons

E. it indicates the numberof protonsin the signal

1.9 Which of the following type of protons are chemically equivalent?

A. Homotopic

B. Enantiotopic

C. Diastereotopic

D.A&B

E.B&C

of 16

1.10 Whatis the IUPAC nameforthe following compound?

AZ

A. (2E, 4Z)-2,4-hexadiene

B. (2E, 4Z)-1,4-dimethyl-1,3-butadiene

C. (2Z, 4Z)-1,4-dimethyl-1,3-butadiene

D. (2Z, 4Z)-2,4-hexadiene


1.11 Which one of the following dienes is most stable?

A. |

OouC.Ill

D. IV

E. All have the samestability

1.12 Which major product(s) are formed for the following reaction?

fo~HsI I

A. |

B. Il

C.Ill

D. IV

E.V

of 16

1.13 Which oneof the following dienophiles is most reactive in the Diels-Alder reaction?O

OCH;

IV ¥I II \,

Il

A. |

B. Il

C. Ill

D.IV

E.V

1.14 Which oneofthe following compound is nonaromatic?HN @ 9

ZA

N, 1 I IV Vv

A. |

B. Il

C. Ill

D.IV

E.V

1.15 Which one of the following compoundswill undergo the fastest Sn1 reaction?

Q A ( : ) { .I i I IV

A. |

B. Il

C.Ill

D.IV

E.1&IV

of 16

1.16 Which one ofthe following compoundsdoes not undergoFriedel-Crafts reaction?

A. benzene

B. chlorobenzene

C. nitrobenzene

D. toluene

E. tert-butylbenzene

1.17 Predict the major product for the following reaction.

(CH;)3;CCH)Cl_—_

AIC],

CH,C(CH3)3 C(CH3)2CH2CH3 CH(CH3)CH2CH2CH3 CH2CH2CH2CH2CH3 CH2CH2CH(CHs)2

I II I IV Vv

A. |

B. Il

C.Ill

D. IV

E.V

1.18 Which oneof the following compounds would be most reactive toward electrophilic aromatic

substitution?

iNH2 CH3 Cl CCH3 CF3

I Il Ill IV Vv

A.|

B. Il

C. Ill

D. IV

E.V

of 16

1.19 What is the IUPAC nameforthe following compound?O

A. 2,4-dimethyl-2-pentenone

B. 2,5-dimethylcyclopenten-3-one

C. 2,4-dimethylcyclopent-2-enone

D. 3,5-dimethylcyclopent-2-enone

E. 2-methyl-5-methylcyclopent-2-enone


PCC3-methyl-1-octanol_———————>

CH,Cl,

A. 3-methyloctanone

B. 3-methyloctanal

C. 2-methyloctanone

D. 2-methyloctanal

E. 2-methyloctanoic acid

1.21 Whatis the correct IUPAC nameforthe following compound?

O

A. 2,6,6-trimethylbenzaldehyde

B. 1,1,3-trimethylbenzaldehyde

C. 2,6,6-trimethyl-1,3-cyclohexadienecarbaldehyde

D. 1,1,3-trimethyl-2,4-cyclohexadienecarbaldehyde

E. 1,1,3-trimethanal-2,4-cyclohexadiene

of 16

1.22 Rank the following acids in decreasing orderofacidity.Oo 9 9

OH ‘OH arco

I cl q F " Br

Oo 9

AK, OH

IV Vv i

A. V>III>1>1I>1V

B. II>1>1II>V>1V

C. IV>III>I>1>V

D. IV>V>III>I>11

E. V>I>II>II>1V

1.23 Whatis the IUPAC nameforthe following compound?0

Aw

A. 2-methylbutyl-3-methylbutanoate

B. 3-methylbutyl-3-methylbutanoate

C. 2-methylbutyl isovalerate

D. 2-methylbutyl-2-methylbutanoate



O

CH;CH,OHa

Cl pyridine

A. ethyl-3-methylbutanoate

B. ethyl-2-methylpropanoate

C. isobutylethanoate

D. 5-methyl-3-hexanone

E. Noneof the above

of 16

1.25 The formation of a thermodynamic enolate is favoured by:

A. keeping the reaction as cold as possible

B. using an aprotic solvent, such as THF

C. using a protic solvent, such as ethanol

D. using a carboxylic acid

1.26 What are the three steps in the malonic ester synthesis, listed in the correct order?

A. Deprotonation, alkylation, hydrolysis/decarboxylation

B. Hydrogenation,alkylation, deprotonation

C. alkylation, hydrolysis/decarboxylation, hydrogenation

D. hydrolysis/decarboxylation, deprotonation,alkylation

1.27 The aldol condensation can be described as involving both:

A. alpha substitution and nucleophilic addition

B. alpha substitution and acyl substitution

C. nucleophilic acyl addition and dehydration

D. nucleophilic acyl substitution and dehydration

1.28 Which one of the following compounds would favor the enol tautomeroverthe ketone

tautomer?

ISNSA

I 0 II 0 ml

SAKE

IV VvO

A. |

B. Il

C.Ill

D. IV

E.V

of 16

1.29 Predict the major product for the following reaction.

OH K,Cr,07/H2SO,/H,0 1. Br,/PBr;

2. H,O

0 O

Br Br Br

H Br OH Br Br

; Br ‘i Il IV Vv

A. |

B. Il

C.Ill

D.IV

E.V

1.30 Which of the following ketones cannot be prepared using acetoacetic ester synthesis?

Ak LO |

A. |

B. Il

C.Ill

D.IV

E.A&C

END OF SECTION A

of 16

SECTION B: [40]

QUESTION2 [12]

Determine the structures of compoundsA to F below.

Note: Each question carries 2 marks.

NagCr,07

HySO,, H2O

[H*]—

D EtOH A

E | eos

1) LiAI(OR)3HNa

F 2) H,O 6

Excess

NH,

C

QUESTION3 [8]

Determine the lettered reagents (A-D) required for each of the following transformation.

Note: Each question carries 2 marks

Oo oO Oo oO HO --

D A, 2?\008 _B LJ co aN _D- xn

VS \ CO.Et ‘a

of 16

QUESTION 4 [10]

Draw a detailed stepwise retro-aldol mechanism showing howthefollowing product is formed.

O O

eA ONaO#, HO JLrs +

Heat

QUESTION 5[10]

An unknown compoundA has the molecular formula Ci2HisO. A absorbsstrongly in the IR at

1715 cm. The +H NMR spectral data for A are given below. Whatis the structure of A?

absorption ppm ratio of absorbing H’s

singlet 1.0 6triplet 1.2 3

quartet 2.2 2

broad singlet 7.0 5

THE END

GOODLUCK

of 16

1H NMR SPECTRAL DATA

Characteristic Chemical Shifts of Common Typesof Protons

Type of proton

Chemical shift (ppm) Type of proton Chemicalshift (ppm)

H

\oac/ 4.5-60.9-2 / AN

en2sp

~0.9

~1.3 «pH 6.5-8~1.7

5 ifoem XZ 3-10

R H

R~2.5 cy 10-12

R OH

2.5-4RO-H or BH 1-5

Important IR Absorptions

Approximate ¥ (cm7’) IntensityBond type

O-H

N-H

3600-3200

3500-3200

~3000

3000-2850

3150-3000

3300

2250

2250

1800-1650 (often ~1700)

1650

1600, 1500

strong, broad

medium

strong

medium

medium

medium

medium

strong

medium

medium

of 16

conjugatebase

H.SO

,su

lfur

icacid

hydr

oiod

ieacid

HI

hydrobromic

acid

hydr

ochl

oric

acid

carbocationsn~J

——_»

weANE

prot

onat

edeHTe

alcohol

aos

i+

hydroniumion

7)

nitric

acid

hydr

oflu

oric

acid

H-——.

f-

20%

20%

carb

oxyl

icac

idsJL

~4>

J,—

g6:

pKaChart ph

enols

-7

water

3primaryalcohols

alky

nes

hydrogen

wNmM

onia

‘ami

nes

alka

nes

conjugateacid

hydrogency

anid

e

H—-C=N

>———

C=C-—-H-_-_—

ef

conjugatebase

*H

“CEN!

(cyanide)

(hyd

roxi

dewon

un

(alkoxides)

C=c:_

(ace

tyli

deanions)

(hydride)

ee N

R7"H

(amide

base

s)

AN

9.1

15.7

16 26

~60

hydrogen

1 H1.0079

fthium

Li 6.941

Deryilium

4 Be

9.01

22

sodium

11 Na

22.990

magn

esiu

m

Mg

24.305

potassium

19 K39

.098

calcium

20

Ca

40.078

tubi

dium

37

Rb

85.4

68

stro

ntiu

m

38

Sr

87.6

2

carbon

6 C 12.011

nitrogen

7 N14.007

oxygen

15.989

fluorine

9 F

18.9

98

sili

con

Si 28.0

86

phosphorus

15 p

20.9

74

sulfur

32.0

65

chlo

rine

17 Cl 35.4

53

scandium

21

Sc

44.956

titanium

Ti 47.867

vanadium

23 V 50.9

42

chromium

24 Cr

51.9

96

manganese

25

Nin

54.938

26 Fe

55.8

45

coba

lt

27

Co

§8.9

33

nickel

Ni 58.6

93

30 2n

65.39

germanium

32

Ge

72.61

arsenic

33

As

74.922

sele

nium

34 78.96

bromine

35

Br

79.904

yttr

ium

39 Y 88.906

zirconium

40

2r

91.2

24

niob

ium

41 Nb

92.966.

moly

bden

um

42

Mo

95.9

4

technetium

43

Tec

(98)

ruthenium

44

Ru

101.07

rhodium

45

Rh

102.91

palladium

46

Pd

106.42

cadmium

48 Cd

112.41

114.82

50 Sn

118.74

antimony

51 Sb

121.

76

tefurium

52 Te

127.

60

iodine

53

126.90

caesium

55

Cs

132.91

barium

56 Ba

137.

33

57-70

lute

tium

71

Lu

174.97

hafnium

72 Hf 178.49

tantalum

73 Ta

186.95

tungsten

74 W 183.84

thenium

75

Re

186.21

osmium

76

Os

196.23

iridium

77 Ir192.22

plat

inum

78 Pt 195.

08

mercury

80 Hg

200.59

thatlium

81 Tl 204.38

Pb

207.2

bism

uth

Bi 208.98

polonium

84

Po

(209

) as

tati

ne

85 At

[210

] fr

ancium

87 Fr (222

) f

adium

88 Ra

(226}

89-102

KK

lawrencium

103

Lr (262)

sulherfordium

104

Rf (261)

dubnium

105

Db

[2

62]

seaborgium

106

Sg

(266

bohr

ium

107

Bh

(264

) ha

ssium

108

Hs

[269

} me

itnerium

109

Mt

[262

] un

unni

lium

110

Uun

[271]

ununbium

112

Uub

[277]

*Lanthanide

seri

es

**Actinide

series

ununquadium

114

Uug

lanthanum

57

La

138.91

cefi

um

58 Ce

140.12

praseodymium

59 Pr 140.91

neodymium

60 Nd

144.

24

promethium

61

Pm

{145

}

samarium

62

Sm

156.36

europium

63

Eu

151.

96

gado

lini

um

64

Gd

157.25

terbium

65 Tb

158.93

dysprosium

66 Dy 162.50

holmium

67

Ho

164.

93

erbium

68 Er

167.26

thulium

69

Tm

168.

93

yiterbium

70 Yb

173.

04 ac

tini

um

89

Ac

(227

) th

orium

90 Th

232.04

protactinium

91 Pa

23

1.04

uranium

92 U238.03

neptunium

plutonium

94

Pu

(244

) a

mericium

95

Am

(243

} cu

rium

96

Cm

(247

) be

rkelium

97 Bk

{247

] ca

lfor

nium

98 Cf {251}

eins

tein

ium

99

Es

(252)

fermium

100

Fm

(257

) me

ndel

eviu

m|

101

Md

{2

58}

nobe

lium

102

No

{259}

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