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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
E. None of the above
[60]
[60]
Page 2 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
E. None of the above
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
Page 3 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
E. None of the above
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
Page 4 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
E. None of the above
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
Page 5 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
Page 6 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
Page 7 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
1.20 Predict the productfor the following reaction.
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
Page 8 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
E. None of the above
1.24 Predict the productfor the following reaction.
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
Page 9 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
Page 10 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
Page 11 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
Page 12 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
Page 13 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
Page 14 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}
Page16of
16