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ORC601S - ORGANIC CHEMISTRY 1 - 1ST OPP - JUNE 2022 |
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1.1 Page 1 |
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p
NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH, APPLIED SCIENCES AND NATURAL RESOURCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
LEVEL: 6
COURSE CODE: ORC601S
COURSE NAME: ORGANIC CHEMISTRY 1
SESSION: JUNE 2022
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
EXAMINER(S) | MR. DAVID NANHAPO
MODERATOR: | PROF. HABAUKA KWAAMBWA
INSTRUCTIONS
Answer ALL the questions.
Write clearly and neatly.
Number the answers clearly
All written work must be done in blue or black ink and sketches
can be done in pencil
5. No books, notes and other additional aids are allowed
PERMISSIBLE MATERIALS
Non-programmable Calculators
ATTACHMENTS
pKa Chart and Periodic Table
THIS QUESTION PAPER CONSISTS OF 14 PAGES
(Including this front page, pKa Chart and Periodic Table)
Page 1 of 14
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1.2 Page 2 |
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SECTION A
[50]
QUESTION 1: Multiple Choice Questions
[50]
e There are 25 multiple choice questions in this section. Each question carries
2 marks.
e Answer ALL questions by selecting the letter of the correct answer.
e Choose the best possible answer for each question, even if you think there is
another possible answer that is not given.
1.1 Rank the acidity of the labelled protons in the following molecule from the lowest to the
highest acidity.
Hp
HO
A. Ha; Hb; He
0
B. Hb; Hc; Ha
C. Hc; Ha; Hb
D. Hb; Ha; He
1.2 List the following compounds in the order of increasing acidity.
A ™~
A. A; B; C; D
B. A; C; B; D
C. A; C; D; B
D. D; C; A; B
O
B. xg,
C. CH3OH
1.4 What is the IUPAC name for the structure below?
O
D. RAG
OH
A. 3-ethyl-4-methyl-2-hexanol
B. 2-ethyl-1,3-dimethyl-1-heptanol
C. 4-ethyl-3,5-dimethyl-5-hexanol
D. (1-hydroxyethyl)-3-methylhexane
Page 2 of 14
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1.3 Page 3 |
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1.4 Designate the following compound as R or S configuration.
A.R
B.S
C. R,S
D. None
of the
above
1.5 Does the equilibrium of this reaction lie to the left or right?
O
5 + CHOH ———
O
OH
+ CHO”
A. Left
B. Right
C. It cannot be determined
D. The forward and reverse reactions are equally favoured.
1.6 Determine the product(s) in the reaction below.
AN
OH
wi
HBr
——
“Br
> "pr
A.
B.
Cc.
1.7 Which compound would you predict to be highest in energy?
ACl
Rt
step 1
_
HO
step 2
+
Op
—Csl
JOH
step 3
A
B
A.A
ce
D
B.B
e¢
D.D
+ Ha
Page 3 of 14
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1.4 Page 4 |
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1.8 How many stereogenic centres does the addictive drug heroin have?
CH3COO
CH,cOoO™
heroin
4
addicting drug
5
6
7
1.9 In question 1.7 above, what kind of reaction does the conversion ofA to D represent?
A. Addition
B. Elimination
C. Subtraction
D. Substitution
1.10 Which of the following statements is (are) true about the energy diagram drawn
below?
reaction
A. The reaction mechanism has two steps
B. b labels a transition state.
C. The overall reaction is endothermic
D. The conversion of a to b is faster than the conversion of b to c.
Page 4 of 14
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1.5 Page 5 |
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1.11 What is the IUPAC name for the structure below?
cl H
A. (R)-3-chloro-6-ethyloctane
B. (S)-3-chloro-6-ethyloctane
C. (S)-6-chloro-3-ethyloctane
D. (R)-6-chloro-3-ethyloctane
1.12 Which of the following compounds is most likely to show first-order kinetics in a
substitution reaction?
Br
A
A.A
B.B
C.C
D.D
B
Cc
D
1.13 Given the following substitution reaction, what would the effect be of changing the
solvent from ethanol to DMSO?
CH3(CHz)sBr + NaOH —>
CH3(CH2)S(OH + Br
A. The rate would increase because Sy2 reactions favour a polar aprotic solvent
B. The rate would decrease because Sy1 reactions favour a polar protic solvent
C. The rate would not be affected by the change in solvent.
D. The potential change cannot be predicted
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1.6 Page 6 |
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1.14 Which of the following anions is the best leaving group?
A) NH2
A.A
B.B
C..G
D.D
B) CI
OC) CH3
+#2.D) OH
1.15 Which of the following is the strongest nucleophile in polar protic solvents?
A) F
B)CH30 C) HO
D) CH3S”
A.A
B.B
GG
D.D
1.16 Which of the following carbocations is the most stable?
*
+
+
+
A
B
Cc
D
A.A
B.B
C.C
D.D
1.17 Which alkyl halide (A-C) would give the following alkene (Y) as the only product in an
elimination reaction?
A An TD LG
Cl
A
B
Cc
Y
A.A
B. B
C.C
D. AandB
Page 6 of 14
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1.7 Page 7 |
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1.18 Which of the following statements is (are) true about an E2 elimination reaction?
A. It is fastest with 3° Halides
B. It exhibits second-order kinetics
C. A better leaving group should make a faster reaction
D. All of the above are true
1.19 A tertiary halide reacts with a weak base and nucleophile. The reaction will proceed
via which of the following mechanism(s)?
A. Sn1
B. Sn and E1
C. E2
D. Sn1 and E2
1.20 Give the IUPAC name for the following compound.
Br
Cl
A. (Z)-1-bromo-2-chloro-2-ethyl-4-methyl-1-pentene
B. (E)-1-bromo-1-chloro-2-ethyl-4-methyl-2-pentene
C. (Z)-1-bromo-1-chloro-2-ethyl-4-methyl-1-pentene
D. (E)-1-bromo-1-chloro-2-ethyl-4-methyl-1-pentene
1.21 Which of the following reaction conditions would result in the anti-Markovnikov addition
to the alkene?
A) H,O/H* B) HBr C) HC! _ D) [1] BHs; [2] H,O/OH
1.22 Give the IUPAC name of the following compound.
CH3C(CH3)2CH2C==CCH2CH(CH2CH2CH3)CH3
A. 2,2,7-trimethyl-4-nonyne
B. 2,2,7-trimethyl-4-decyne
C. 3,3,7-trimethyl-4-decyne
D. 2,2,6-trimethyl-4-undecyne
Page 7 of 14
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1.8 Page 8 |
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1.23 What is the product of the following reaction?
AF
1 NaNHe
S 2. CHe gCHal anal
NH»
A. AF
3. AF
.
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Z
7
a
1.24 How many peaks could theoretically be observed in the 'H NMR signal(s) for
each of the indicated atoms?
H <—
Cl
H
H
H
A. a: 7; b: 4; c: 3; d: 3
B. a: 7; b: 3; c: 3; d: 3
C. a: 7; b: 4; c: 2; d: 4
D. a: 7; b: 4; c: 3; d: 4
1.25 Which of the following is the correct structure for 1-bromo-2,4-dimethoxybenzene?
OMe
MeO
Br
“Ty Br
cor
Br
;
MeO
OMe
A
B
MeO
Cc
- OMe
OMe
D
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1.9 Page 9 |
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SECTION B:
[50]
QUESTION 2
[10]
2.1 Show with arrows, how the following products are formed.
(2)
» As
+ HG2r
°
hg + HeO
b) J9
OH
+
H—O+-H
H
—__—____—_~
FOH
ye
OH
+ HO
2.2 Assign R and S configuration to all possible stereoisomers of 1-Bromo-2-
methylcyclopentane.
(8)
QUESTION 3
[10]
3.1 Name and label all the functional groups in the structure. Be sure to indicate primary (1°),
secondary (2°) or tertiary (3°), where appropriate.
(4)
0.
OV
Tamiflu
3.2 Draw bond-line structures of the following molecules:
(6)
a) 2-chloro-1, 7, 7-trimethylbicyclo [2.2.1] heptane
b) 3-ethyl-6-methyl-5-propylnonane
c) 2, 6-dimethyl-4-(2-methylpropyl)decane
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1.10 Page 10 |
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QUESTION 4
[12]
4.1 Predict the product(s) of the following reaction
(12)
a
onHBr
b) oS
RHBOrOR
Light
c) Jow S
d) YS
Hm2eSO4 ~
sHo,O,"
e) ees
1. Hg(OAc)>, H2O
— 2. —Na—B— H,— , —N— aO— H —
f) oS
— 21,. NBaHO2H/— ,THFH,0>, H,0
Page 10 of 14
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2 Pages 11-20 |
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2.1 Page 11 |
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QUESTION 5
[10]
5.1 Assign formal the charge to each atom in the following structure:
(4)
(a)
FORMAL CHARGE
a) O
Oe b) OL
||
c) N
d) O
(b) OQ, 0, °°
A“ (c) N\\
*.
5.2 Give (i) a reaction equation and (ii) full mechanism for the acid-catalyzed (HCI) addition of water
to 1-methyl-1-cyclopentene.
(6)
QUESTION 6
[3]
An Unknown compound X has the molecular formula CgHi40. X shows a peak in its IR spectrum at
3200 — 3600 cm. The +H NMR Spectral data of X are given below. What is the most likely Structure
of X?
absorption
5
singlet
1.0
doublet
Lie
singlet
3.0
quartet
3.5
H ratio
9
3s
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END OF EXAMINATION QUESTIONS
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2.2 Page 12 |
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1H NMR SPECTRAL DATA
Type of proton
tu
sp? |
Characteristic Chemical
Chemical shift (ppm)
0.9-2
.
Shifts of Common Types of Protons
Type of proton
Chemical shift (ppm)
H
Nek
sp*
45-6
° RCH,
~0.9
e RsCHs
~1.3
° R,CH
~A7
Cp
6.5-8
‘ C—C—|| -H
Z=C,O,N
—C=C-H
sp adbazZ rs
Z=N,0,X
1.5-2.5
~2.5
2.5-4
RoiolO H
R~ S°L ~OH
RO-H or R-N-| H
9-10
10-12
15
Bond type
O-H
N-H
C-H
° C.2-H
e C.2-H
¢@ Cs.-H
C=C
C=N
G=0
C=C
Important IR Absorptions
Approximate V (cm™)
3600-3200
3500-3200
~3000
3000-2850
3150-3000
3300
2250
2250
1800-1650 (often ~1700)
1650
1600, 1500
intensity
strong, broad
medium
strong
medium
medium
medium
medium
strong
medium
medium
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2.3 Page 13 |
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2.4 Page 14 |
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