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ORC601S - ORGANIC CHEMISTRY 1 - 2ND OPP - JULY 2022 |
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1.1 Page 1 |
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©
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: JULY 2022
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
SECOND OPPORTUNITY/SUPPLEMENTARY 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 13 PAGES
(Including this front page, pKa Chart and Periodic Table)
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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 What is the IUPAC name for the structure below?
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
1.2 List the following compounds in the order of increasing acidity.
A ™~
O
B. vou
C. CH,OH
A. A; B; C; D
B. A; C; B; D
C. A; C; D; B
D. D; C; A; B
1.3 Give the IUPAC name for the following compound.
O
D. RAM
A. (Z)-2,3,6-trimethyl-2-heptene
B. (Z)-2,3,6-trimethyl-3-heptene
C. (E)-2,3,6-trimethyl-3-heptene
D. (E)-2,3,6-trimethyl-2-heptene
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1.3 Page 3 |
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1.4 Does the equilibrium of this reaction lie to the left or right?
O
O
6
+ CH30H
—_—_
OH
+ CH30"
A. Left
B. Right
C. It cannot be determined
D. The forward and reverse reactions are equally favoured.
1.5 Which is the order of increasing acid strength of the following compounds?
i
F OQ
0
F
O
As
OH SK
OH
Yo
OH
LAA,
F
FE
I
0
I
IV
A. |, Ill, Il, IV
B. IV, Ill, Il, |
CG. Hl. 1, UL IV
D. IV, Ill, |, Il
E. Ill, IV, Il, |
1.6 Identify the following compounds as R or S.
Br
F——C—CH;
| 2p
oH
cl
A. S,S,R
B. S,R,S
C. R,S,S
D. S,S,S
E. R,R,R
OH OH
HCH;
cl—C-—F
CH;
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1.4 Page 4 |
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1.7 How many stereogenic centres does the addictive drug heroin have?
CH3COO
CH,coo”™
heroin
addicting drug
1.8 Consider the three isomeric alkanes n-hexane, 2, 3-dimethylbutane, and 2-methylpentane.
Which of the following correctly lists these compounds in order of increasing boiling point?
2, 3-dimethylbutane < 2-methylpentane < n-hexane
2-methylpentane < n-hexane < 2, 3-dimethylbutane
2-methylpentane < 2, 3-dimethylbutane < n-hexane
n-hexane < 2-methylpentane < 2, 3-dimethylbutane
n-hexane < 2, 3-dimethylbutane < 2-methylpentane
1.9 Among the butane conformers, which occur at energy minima on a graph of potential energy
versus dihedral angle?
gauche only
eclipsed and totally eclipsed
gauche and anti
eclipsed only
anti only
1.10 Given the following substitution reaction, what would the effect be of changing the solvent
from ethanol to DMSO?
CH3(CH2)sBr + NaOH
————
CH3(CH2)50H + Br
A. The rate would increase because Sy2 reactions favour a polar aprotic solvent
B. The rate would decrease because Swi 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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1.5 Page 5 |
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1.11 Which of the following anions is the best leaving group?
A) NH2
B) CI
C) CH3
#2.D) OH
A.A
B.B
LG
D.D
1.12 Which of the following compounds will react most rapidly with HCI?
5-methyl-1-hexene
4-methyl-1-hexene
(E)-5-methyl-2-hexene
(E)-2-methyl-3-hexene
2-methyl-2-hexene
1.13 Which of the following is the strongest nucleophile in polar protic solvents?
A) FB) CH30° C) HO
D) CH3S”
1.14 What is the major product from the acid-catalyzed hydration of 2-methyl-2-pentene?
2-methylpentane
2-methyl-1-pentanol
2-methyl-2-pentanol
2-methyl-3-pentanol
1-methoxypentane
1.15 Give the product for the reaction of 1-butene with methanol in the presence of acid.
1-ethoxybutane
2-ethoxybutane
1-methoxybutane
2-methoxybutane
1-butanol
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1.6 Page 6 |
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1.19 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
1.20 Assuming no other changes, what is the effect of doubling both the alkyl halide and the
nucleophile concentrations in a Sy2 reaction?
A. no change
B. doubles the rate
triples the rate
quadruples the rate
rate is halved
1.21 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
1.22 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] BH3;:; [2] H,O./OH
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1.7 Page 7 |
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1.23 What is the nucleophilic site in each of the following molecules?
A. He"35 SCH
B. H»oNe—CH3
C. H»C—_=Ch»
A) A: hydrogen; B: nitrogen; C: 2 electrons in bond
B) A: oxygen: B: nitrogen: C: carbon
C) A: oxygen; B: nitrogen; C: 2 electrons in bond
D) A: oxygen: B: carbon; C: 7 electrons in bond
1.24 Which compound has the highest boiling point?
.
CHyCH)CH)CH»CH»CH»CH3
a)
H3C
* CHCH2CH3CH;
H3C
b)
CECH
HyC—C—CHy
CH)CH;
c)
()
d)
1.25 What is the correct stereochemical name for the following compound?
(2S,3S)-2-bromo-3-chlorobutane
(2R,3R)-2-bromo-3-chlorobutane
(2R,3S)-2-bromo-3-chlorobutane
(2S,3R)-2-bromo-3-chlorobutane
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1.8 Page 8 |
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SECTION B:
[50]
QUESTION 2
[10]
2.1 Give IUPAC names for the following compounds:
Note: Each question carries 2 marks.
a
b.
Cc
d.
8
QUESTION 3
[20]
i 3.1 Give an IUPAC name for the following compounds
O
Oo
(6)
CHS ~OCH.CH;
H3CH2C7~ ~OH
~J
a)
b)
c)
3.2 Draw the skeletal structures of the following molecules.
(6)
(a) (4E)-2,4-dimethyl-1,4-hexadiene
(b) cis-3,3-dimethyl-4-propyl-1,5-octadiene
(c) trans-2,2,5,5-tetramethyl-3-hexene
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1.9 Page 9 |
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3.3 Predict the products of the following reactions, showing regiochemistry and stereochemistry
where necessary.
(8)
(a)
CH3
(b)
]
1.03
2
2. Zn, H30*
.
H
(c)
] CH3
1. BH3
»5
(d)
2. HyO», —OH
:
KMn0Oq4
H30t
CH3 1. Hg(OAc)2, H2O
9
2. NaBH4
,
QUESTION 4
[10]
Predict the products of the following reactions. Indicate the stereochemistry in the products when
relevant.
Note: Each question carries 2 marks.
(a)
120, FHA.SSOO,, |
(d)
om
B(4)Hy:THF
@) NaOH, Ho,
Br. |
M(Y1)O5
(@(2) Me.S
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1.10 Page 10 |
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QUESTION 5
[10]
5.1 Identify each of the following reactions as addition, elimination, substitution or rearrangement.
(4)
(a) CH3CHoBr + NaCN — > CHgCHoCN (+ NaBr)
“catalyst —
—H_e—a_t —
(d)
+ ON—NO, —Li—ght
O
NO>
(+ HNO»)
5.2 Using skeletal structures, draw a full detailed mechanism of the reaction of 1-propene with
ethanol in the presence of hydrochloric acid. In order to receive full marks, show the flow of electrons
using arrows and all the intermediates which are formed during the reaction.
(6)
Hint: the reaction produces an alkyl halide and an ether as products
END OF EXAMINATION QUESTIONS
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