namibia university of science andtechnology
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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: 6
COURSE CODE: ORC601S COURSE NAME: ORGANIC CHEMISTRY 1
SESSION: JULY 2018 PAPER: THEORY DURATION: 3 HOURS MARKS: 100
SECOND OPPORTUNITY/SUPPLEMENTARY EXAMINATION QUESTION PAPER
EXAMINER(S) MR. DAVID NANHAPO
MODERATOR: PROF. HABAUKA KWAAMBWA
INSTRUCTIONS
AnswerALL the questions.
Write clearly and neatly.
Numberthe answersclearly
Pwhy
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
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)
SECTION A [50]
QUESTION1: 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 answerfor each question, even if you think thereis
another possible answerthatis not given.
1.1 Consider the following molecule having three labelled protons, Ha, H,b and Hc. Rank these
protonsin orderof increasing acidity.
HpO Oy,
Ha He
A. Ha; Hb; He O
B. Hb; Hc; Ha
C. He; Hb; Ha
D. Hb; Ha; Hc
1.2 Arrange the followingin orderof increasing basicity?
I. OH Il. Cl- I. HO IV. NH:
A.Il, Il, IV, |
B. II, 1, IV, I
C.1V, 1, Hl, Hl
D. Ill, IV, 1, I
E. I, Il, Ul, IV
1.3 Which of the following alkanes would have the lowest boiling point?
A. CH3CH2CH2CH2CH2CH2CHs
B. (CH3)3CCH(CHs)2
C. CH3CH2CH2CH2CH(CH3)2
D. (CH3)2CHCH2CH(CHs)2
Page 2 of 13
1.4 Whatis the IUPAC nameofthe following compound?
S&
4-vinyl-2-pentyne
4-methylhex-2-yn-5-ene
3-methylhex-4-yn-1-ene
090
BP>
3-methylhex-1-en-4-yne
E. none of the above
1.5 The most stable conformation ofcis-1-tert-butyl-2-methylcyclohexaneis the onein which:
A. the tert-butyl group is axial and the methyl group is equatorial.
B. the methyl groupis axial and the tert-butyl is equatorial.
C. both groups are equatorial.
D. both groupsareaxial.
E. the twist boat conformation is adopted.
1.6 Consider the following acid-base reaction. The equilibrium for this reaction lies to the:
. H+ ZN ——=__— _ N
H3C-CH,-C==CH -H3C CH3 H3C-CH2-C==c: + HyC~CH
A. Left
B. Right
C. It cannot be determined
D. The forward and reversereactions are equally favoured
1.7 Which ofthe following is not a nucleophile?
A. CN
B. CH3NH2
C. CH30"
D. H20
E. *NO2
Page 3 of 13
1.8 What is the HCH bond angle in the compound shown below?mono
FfP
1.9 Which compound(s)is/are chiral?
CH3
CH;
A
B.
C
D
~60°
~90°
~109.5°
~120°
~180°
A
Cl
Cl
A
AandB
C
. BandC
CH
CHs Br
CHs3 Cl
Aw
DCH3
rly Br CH Gy
q CHg
1.10 How manystereogenic centres are presentin the following compound?
moOoOW
D>
BWNPF
O
OH
Page 4 of 13
1.11 Identify the following compoundsasR or S.
=
o— ~ —O =k O
O x=
1
H™
S,S,R
S,R,S
R, 3,5
S, S$, 5S
R,R, RmooawpD
1.12 Which of the following is a product of the acid-catalyzed hydration of 3-methyl-2-pentene?
A. 2-methylpentane
3-methyl-1-pentanol
3-methyl-3-pentanol
2-methyl-2,3-pentadiol
mono
8
3-methyoxypentane
1.13 What product results from the Sn2 reaction between(R)-2-chloropentane and the hydroxide
ion?
A. (R)-2-pentanol
B. (S)-2-pentanol
C. 1:1 mixture of (S)-2-pentanol and (R)-2-pentanol
D. (S)-2-chloropentane
E. (R)-2-chloro-2-pentanol
1.14 Which of the following reactions proceeds with inversion of configuration at the carbon
bearing the leaving group?
A. Sn2
B. Sn
C.E1
D. E2
E. All of the above
Page 5 of 13
1.15 Whatis the product of the following reaction?
a 1. NaNHo
—_
2. CH3CH!
A. AZ B. AA C. AE D. oe
1.16 How many possible stereoisomersare possible for the following compound?
Br
NH>
A. 2
B. 4
C8
D. 16
1.17 Determine the product(s) in the reaction below.
+ HBr —_—>
A D. AandB
1.18 What is the molecular geometry of the central atom in CH30CH3?
A. Trigonal planar
B. Trigonal pyramidal
C. Tetrahedral
D. Bent
Page 6 of 13
1.19 Which of the following cannot exhibit chirality?
2, 3-dibromobutane
1, 3-dibromobutane
1, 2-dichlorobutane
99
7>
1, 4-dibromobutane
1.20 Which of the following is the strongest nucleophile in aqueous solution?
A. HO"
B. F
Cc. Br
D.I
1.21 Which of the following carbocations is the most stable?
ro oO &A.A
B.B
C.C
D.D
1.22 Which of the following statementsis (are) true about an E1 elimination reaction?
A. It is fastest with 3° Halides
B. The identity of the base affects the rate of reaction
C. A better leaving group increases the reaction rate
D. All of the above are true
1.23 Which of the following are enantiomers?
A. A pair of cis-trans isomers
B. Two constitutional isomers
C. A chiral molecule and its mirror image
D. A molecule with a chiral center and its superimposable mirror image
Page 7 of 13
1.24 Markovnikov addition of HBr to 2-methyl-2-pentene involves:
A.Initial attack of bromide ion
B. Formation of a tertiary carbocation
C. Formation of a secondary carbocation
D. Formation of a primary carbocation
1.25 What is the IUPAC name forthe 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
Page 8 of 13
SECTION B: [50]
QUESTION 2 [10]
Whatis (are) the product(s) of the following reactions? Represent the products as skeletal
structures and show the stereochemistry where necessary.
Note: Each question carries 2 marks.
Substitution only
a) "Br + CH,OH Sa
b) Le + pe i:
Br msNH,
——_—_—__—_—_>c) :Br {2 equivalents)
1) BH3mari
dd “NN 2) H2O/OH™
Hae) —_—
— _
Lindlar's catalyst
Page 9 of 13
QUESTION3 [10]
Determine the reagents required to achieve the following transformation.
Note: Each question carries 2 marks.
? O
Dh yokAr
ey Ee>
‘) ) | Q= Br OH r OH
? O
qd = LW en
+
t B
O~
ol : O.e)_—_NOs NO,
Br
a“
QUESTION 4 [10]
4.1. Draw the following compoundin standard three-dimensional format using wedge and dashed
bonds:
(2R,3R)-pentan-2,3-diol (2)
4.2. Give the R, S -configuration for the stereogenic centers (marked with an asterisk) in the
compoundsshownbelow. Show howyouarrive at your answer. (2)
(i) H OH (ii)HO Z
* ~CH»NHCH3
HO
Page 10 of 13
4.3. Camphoris optically active. A camphor sample (1.5 g) dissolved in ethanol to a total volume
of 5 mL, placed in a 3 dm polarimeter sample tube, gives an observed rotation of +2.5° at 20°C
(using the sodium D-line). Calculate and express the specific rotation of camphor. (4)
QUESTION 5 [10]
Considerthe following reaction below and answerthe questionsthatfollow.
CHs CH;CHa—G—CH;CHs + H,0 cH,-G-CH,CH, + I
I H,
a. Draw a mechanism for this reaction using curved arrows. (2)
b. Draw an energy level diagram and label the axes, starting material, product, Fa and AH°.
Assumethat the starting material and product are equalin energy. (2)
c. Draw the structuresof the transition states. (2)
d. Whatis the rate of the reaction? (1)
What happensto the reactionif:
i. The leaving group is changed from Ito Cl? (1)
ii. |The solvent is changed from H20 to DMF? (1)
iii. |The concentration of H20 is increased by a factorof five? (1)
QUESTION 6 [10]
Determine the mechanism of nucleophilic substitution (either Sn1 or Sn2) of each reaction and draw
the products, including the stereochemistry.
Note: Each question carries 2 marks.
H
a. Me + “CN ———acetone
b. AN? + -OCH,% DMSO
Br H
GHeCHs
Cling,d. H~ Vl + CHgCOOH
CH,
f \e. / \ + ~OCH,CH,NAsa DMF
THE END
Page 11 of 13
conjugateacid
conjugatebase
sulfuric
acid
HgSO,———
Hsa;
hydroiodie
acid
Hl——»
|-
hydrobromic
acid
—+.
5 sCli
protonated
alco
hol
hydroniumion
y
nitric
acid
hydrofluoric
acid
"0:
03
carboxylic
acidsBR--H
JL,—
oa
pKaChart ph
enols
-7
water
3primaryalcohols
alkynes
hydrogen
wnmonia‘anines
alkanes
4.8
eonjusateacid
hydrogen
cyanide
"CEN:
(cyanide)
H-C=N
:——>
ue
Sa—_—_»
:0—-H
(hydroxide)
(alkoxides)
C=c:
(acetylide
anions)
—~——_
*H
hydride)
’NT
Roe
ty
—_—_—_——Rwy
(amide
bases)
“oN
ot
.
9.1
15.7
16 26 Ww
et
~60
hydrogen
1 H1.
0079
lithium
3 Li 6.941
bery
lliu
m
4 Be
9.0122
sodium
11 Na
22.990
magnesium
potassium
19 K29.098
40.0
78
rubi
dium
37 Rb
85.468
strontium
38 Sr
87.6
2
oe
He
4.0026
boron
5 B10.811
carbon
6 C 12.011
nitr
ogen
7 N14.007
oxygen 8 O 15
.999
fluo
rine
9 F
18.998
10
Ne
20.180
aluminium
13 Al 26.982
silicon
Si 28.0
86
phos
phor
us
#6 Pp
30.974
sulfur
16 S
32.065
chlorine
17 Cl 35
.453
,
argon
18 Ar
39.948
scan
dium
21 Sc
44.956
titanium
Ti 47.867
vanadium
23 V 50.9
42
chromium
manganese
iron 26
24
25
Cr|Mn|
Fe
51.9
9654
.938
55.8
45
coba
ltnickel
copper
Co|
Ni}
Cu
58.9
3358.693
63.5
46
zine
30 Zn
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
79.9
04
krypton
36
Kr
83.80
yttrium
39 Y 88.906
zirconium
40
Zr
91.224
niob
ium
A1 Nb
92.906
moly
bden
um}
tech
neti
umru
then
ium
43
44
Mo|
Tc
Ru
95.94
{98}
101.07
rhodium
palladium
silv
er
45
Rh
Pd|Ag
102.
91106.42
107.87
cadmium
48
Cd
112.41
indi
um
49 In 114.82
50 Sn
118.71
antimony
51 Sb
121.76
tellurium
52 Te
127.
60
iodi
ne
53
126.90
xenon
54 Xe
131.
29
caesium
55
Cs
122.91
barium
56 Ba
137.33
57-70
lutetium
71 Lu
174.97
hafnium
72 Hf
178.49
tant
alum
73 Ta
180.95
tung
sten
rhenium
osmium
74(5
WRe|
Os
183.84
186.
2119
0.22
iridium
plat
inum
gold
7779
IrPt
Au
192.22
195.08
196.97
merc
ury
80
Hg
200.59
thallium
81 Tl 204.38
Pb
207.
2
bismuth
Bi 208.98
polonium
84 Po
[209]
asta
tine
85 At
[210] r
adon
86
Rn
(222) fr
ancium
87 Fr
(223)
radi
um
88 Ra
(226)
89-102
x*
favwrencium
103
Lr
[262]
tulh
erfo
rdiu
m
104
Rf
(264)
dubnium
105
Db
(262)
seaborgium
bohrium
hassium
106
107
108
SgBh|
Hs[266]
(264)
[269]
me
itne
rium
ununnilium
unununium
109
110
411
Mt
(Uun/Uuu
(268)
[274]
(272]
un
unbium
112
Uub
[277]
*Lanthanide
series
**Actinide
series
ununquadium
114
Uug
(289]
lanthanum
57 La
138.91
ceri
um
58 Ce
140.12
praseodymium
59 Pr
140.91
neodymium
prom
ethi
umsamarium
Nd|Pm/}Sm
144.24
[145
150.
36
euro
pium
gadolinium
terb
ium
Eu
Gd|
Tb
151.
96187.25
158.
93
dysprosium
Dy
162.
50
holmium
67
Ho
164.93
erbium
68 Er 167.
26
thul
ium
69
Tm
168.
93
ytterbium
70 Yb
173.
04 ac
tinium
89 Ac
[227]
thor
ium
Th
222.04
prot
acti
nium
91 Pa
231.04
uranium
neptunium
plutonium
UNp}
Pu
238.
03(237)
[244]
amer
iciu
mcu
rium
berk
eliu
m
Am|Cm|
Bk
[242]
[247]
[247]
cali
forn
ium
98 Cf [251]
einsteinium
99 Es
{252}
ferm
ium
100
Fm
[257
] me
ndel
eviu
m|
101
Md
{258]
nobe
lium
102
No
[259]
Page13of
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