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OCH701S - ORGANIC CHEMISTRY 2 - 1ST OPP - JUNE 2023 |
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1 Pages 1-10 |
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1.1 Page 1 |
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nAmlBIA unlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
SCHOOLOF NATURALAND APPLIEDSCIENCES
DEPARTMENTOF BIOLOGY,CHEMISTRYAND PHYSICS
QUALIFICATION:BACHELOROF SCIENCE
QUALIFICATIONCODE: 07BOSC
LEVEL: 7
COURSECODE: OCH701S
COURSENAME: ORGANIC CHEMISTRY 2
SESSION:JUNE 2023
PAPER:THEORY
DURATION: 3 HOURS
MARKS: 100
FIRSTOPPORTUNITYEXAMINATION QUESTION PAPER
EXAMINER($) DR. MARIUS MUTORWA
MODERATOR: DR. RENATE HANS
INSTRUCTIONS
1. Answer ALL the questions.
2. Write clearly and neatly.
3. Number the answers clearly
4. All written work must be done in blue or black in and sketches must
be done in pencil
5. No book, notes and other additional aids are allowed
• PERMISSIBLEMATERIALS
Non-programmable Calculators
• ATTACHMENTS
NMR and IR Spectral Data, pKa Chart and Periodic Table
THIS QUESTION PAPERCONSISTSOF 12 PAGES(Including this front page)
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SECTIONA
[50]
• QUESTION 1: Multiple Choice Questions
• There are 25 multiple choice questions and each question carries 2 marks.
• Answer ALL questions by selecting the letter of the correct answer.
[SO]
1.1 Consider the three organic compounds drawn below. Which of the following statements is (are)
true about the IR spectra of A, B, and C?
A
B
A. A shows strong absorptions at 3000 cm-1 and 1700 cm- 1.
B. B shows strong absorptions at 3000 cm-1 and 2250 cm- 1.
C. C shows strong absorptions at 3000 cm-1 and 3200-3600 cm- 1.
D. Statements (A shows strong absorptions at 3000 cm- 1 and 1700 cm- 1) and {C shows strong
absorptions at 300 cm- 1and 3200-3600 cm- 1) are true.
E.Statements (A shows strong absorptions at 3000 cm- 1and 1700 cm- 1), (B shows strong
absorptions at 3000 cm- 1and 2250 cm- 1), and {C shows strong absorptions at 3000 cm- 1 and
3200-3600 cm- 1) are all true.
1.2 Which molecular formula is consistent with the following mass spectrum data?
A. CsH1oO
B.CsHsO
C. CsH24
D. C6H12
E. (4H6O2
M+·at m/z= 84, relative height=l0.0%
(M+lj+" at m/z= 85, relative height=0.56%
1.3 Identify the structure that is consistent with the following data.
0
ef .,,...,.......0
A
a. The IR includes peaks at 1603 and 1495 cm-1.
b. The 13C NMR has a total of 7 signals.
c. The compound has one acidic proton.
OOH -VJOH
'o
B
C
OH 0
0
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1.3 Page 3 |
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A.A
B.B
c.c
D.D
E. None of the above
1.4 Which of the following compounds will produce a prominent (M-18) peak in the mass
spectrum?
A. 2-methylheptane
B. 1-heptanol
C. Heptanamine
D. Heptanal
E. None of the above
1.5 How many different proton environments are present in each of the following
molecules?
OH
A /'--../
8
C
Br
A. A= 6 ; B = 3 and C = 4
B. A= 5; B = 3 and C = 4
C. A =6; B =4 and C = 5
D. A= 6; B = 4 and C = 4
1.6 Which of the indicated protons absorbs furthest downfield in NMR?
A.Ha
B. Hb
C. He
D.Hd
E. He
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1.7 Which of the following type of protons are chemically equivalent?
A. Homotopic
B. Enantiotopic
C. Diastereotopic
D.A&B
E.B& C
1.8 Which of the following compounds is the kinetic product of the reaction of HBr with 1,3-
cyclohexadiene?
A.A
B.B
c.c
D.D
E. A&D
B
C
D
1.9 Which of the following statements about Diels-Alder reaction is false?
A. The reaction is stereospecific
B. The diene must be in the s-cis conformation in order to react
C. The dienophile must contain an electron withdrawing group
D. The diene and dienophile line up so that the exo product is favoured.
1.10 Which of the following dienophiles is most reactive in a Diels-Alder reaction?
0-0H
A
B.
C.
A.A
B.B
c.c
D.D
1.11 Which of the following conjugated dienes would not react with a dienophile in a Diels-Alder
reaction?
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A. I
B. II
C. Ill
D. IV
E. I & Ill
1 CY
rO II.
co II1
Q IV.
1.12 Which of the following compounds is not aromatic?
6 co (±)
0
N
A.
B.
C.
A. A
B.B
c.c
D.D
00h
D.
1.13 What is the IUPACname for the following compound?
A. 6-ethyl-3-nitrobenzoic acid
B. 1-ethyl-4-nitrobenzoic acid
C. 2-ethyl-5-nitrobenzoic acid
D. 2-ethyl-5-nitrobenzaldehyde
E. 4-nitro-3-carboxyethylbenzene
1.14 Which structures are aromatic?
9 0
0
CH,
I
II
COH
II
0
0
N
ill
..
0
(~~)
0
IV
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A. II and Ill
B. Ill and IV
C. I and Ill
D. II and IV
1.15 Arrange the compounds in order of increasing reactivity towards electrophilic substitution?
6 6 0
6II CH3
0
611H,
I
II
ill
IV
A. II, I, IV, Ill
B. I, Ill, IV, II
C. Ill, I, IV, II
D. IV, Ill, II, I
1.16 Which of the following statements is (are) true about electrophilic aromatic substitution?
A. The methoxy group is an ortho, para activator because of a strong electron donating effect
B. The methoxy group is an ortho, para director because of a strong electron withdrawing
inductive effect
C. The methoxy group is an ortho, para activator because the O atom is an electronegative atom
strong electron donating effect
D. Statement A (The methoxy group is an ortho, para activator because of a strong electron
donating effect) and Statement C (the methoxy group is an ortho, para activator because the 0
atom is an electronegative atom strong electron donating effect) are the only true statements.
1.17 What is the structure of the final product resulting from the sequence of reactions shown
below?
A. 1-chloro-4-nitrobenzene
B. 1-chloro-3-nitrobenzene
C. 1-chloro-2nitrobenzene
D. a mixture of 1-chloro-4-nitrobenzene
and 1-chloro-2-nitrobenzene
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1.18 Choose the best reagent to carry out the reaction below?
\\
A. K2Cr2O1,H2SO4,H2O
B. (1) 03, (2) H2O
C. NaOH, H2O
D.NaH
E. None of the above
0
_)lOH
+ ~OH
0
1.19 What is the correct name for the following compound?
CH 3
I
CH3CH2 C=CCH2CH3
I
CH2CH20H
A. 3-methyl-4-ethyl-3-hexen-6-ol
B. 4-ethyl-3-methyl-3,6-hexenol
C. 3-ethyl-4-methyl-3-hexen-1-ol
D. 3-methyl-4-(2-hydroxyethyl)-3-hexene
E. 3-(2-hydroxyethyl)-3-methyl-3-hexene
1.20 Select the correct reagent(s) for the following reaction.
A. LiAIH4/ether; then H3Q+
B. Na8H4; then H3Q+
C. H2 and Pt/C
D. B and C above are correct
1.21 What is the correct name for the following compound?
A. 1,1,2-trimethyl-1,3-hexenone
B. 1,2-dimethyl-1,3-hexenone
C. 2,3-dimethyl-1,3-heptenone
D. 2,3-dimethyl-2-hepten-4-one
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1.22 Select the product of the following reaction.
0
o~OMe
1. LiAIH4
0
HO~OMe
A.
A. A
B.B
c.c
D.D
OH
HO~
B.
0
0~
C.
OH
0~
D.
1.23 Why do aldehydes undergo nucleophilic addition reactions while esters undergo nucleophilic
acyl substitution reactions?
A. The carbonyl carbon of an ester is more electrophilic than that of an aldehyde.
B. Aldehydes are more sterically hindered than esters.
C. Once the nucleophile adds to an aldehyde, the tetrahedral intermediate is too sterically
hindered to eliminate one of the attached groups.
D. The ester carbonyl carbon is sp3 hybridized while the aldehyde carbonyl carbon is sp2
hybridized.
E. Once the nucleophile adds to an aldehyde, neither H- nor R- can be eliminated since they
are strongly basic.
1.24 Which one of the following is the strongest acid?
A. benzoic acid
B. 4-nitrobenzoic acid
C. 4-ethylbenzoic acid
D. 4-chlorobenzoic acid
1.25 Why would the alcohol in the following compound need to be protected before the reaction?
u~H
HO
A. If it is not protected, the product will be a carboxylic acid
B. The Grignard reagent will react with the alcohol before the ketone
C. Magnesium is Lewis acidic and will coordinate with the alcohol
D. There is no need to protect the alcohol
END OF SECTIONA
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1.9 Page 9 |
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SECTIONB
[SO]
QUESTION 2
[16]
Identify the lettered reagents (A-H) in the following reaction sequence.
Note: 2 marks for each intermediate
0
(b)
l (c)
c(H
OH
(a)
():o 0 0H (d)
(f)
Cr° al .OH (e)
1(g)
'OH
(+ enantiomer)
0Br (h)
QUESTION 3
0
[14]
Draw a full detailed mechanism for the reaction below. In order to receive full marks, show all
intermediates and flow of electrons using the appropriate arrows.
Note: 1 mark for each appropriate arrow
ex::ciH ..
+
:o:·
-
QUESTION 4
[20]
Use the 1H NMR spectral table provided to identify the structure of compound X with the
following 1H NMR spectral data:
- Molecular formula: C7 H1402
- 1H NMR (ppm)
: 0.94 (doublet, 6 H)
: 1.15 (triplet, 3 H)
: 1.91 (multiplet, 1 H)
: 2.33 (quartet, 2 H)
: 3.86 (doublet, 2 H)
- IR absorption at -172 0 cm- 1
THE END
GOODLUCK
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1.10 Page 10 |
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1H NMR SPECTRALDATA
Characteristic Chemical Shifts of Common Types of Protons
Type or proton
Chemlcal shirt (ppm)
Type of proton
Chemlcal shift (ppm)
• RCH 3
• R2CH2
• R3CH
z,, I
;C-C-IH
Z=C, 0, N
0.9-2
-0.9
-1.3
-1.7
1.5-2.5
\\
/H
C=C
I/\\
sp2
4.5--6
0-H
6.5--8
9-10
-C::C-H
-2.5
0
II
R_.C.. 'OH
10-12
-6-H sp3/I Z
2.5-4
Z= N,O, X
RO-H or R-N-H
1-5
I
Bond type
Important IR Absorptions
v Approximate (cm- 1)
0-H
N-H
3600--3200
3500--3200
C-H
• Csp3-H
• Cs,,,2-H
• Cs,o-H
C=C
c~N
-3000
3000-2850
3150-3000
3300
2250
2250
C=O
C=C
1800--1650 (often -1700)
1650
0
1600, 1500
Intensity
strong, broad
medium
strong
medium
medium
medium
medium
strong
medium
medium
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2 Pages 11-20 |
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2.1 Page 11 |
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conjugate acid
sulfuric acid
H2S0 4
hydroiodic acid
HI
hydrobromic acid HBr
hydrochloric acid
-.HCI:
H
carbocations
+
protonated
alcohol
,..,,.-...•..•_,.,H
OI +
H
hydronium ion
H,,..0.I·'+H
H
nitric acid
HN0 3
hych-ofluoric acid HF
:o:
)l .. carboxylic acids
0,.,H
conjugate base
... Hso;
,-
....
-
Br
... ..:c1:
... ,..,,.-...•..•_,.,H
..0
H...•0•-•• ,H
N0 3
-
F
:o:
.... )lo:..
pKa Chart
conjugate acid
conjugate base
-10
-9
hydrogen cyanide H-C=N:
:c=N:
9.1
phenols
v?.Hv~=- ..
(cyanide)
10
-8
-7
water
•·o·•
H,.... 'H
...
-
..,..
:o-H
15.7
-3
.. primary alcohols /'--- .o.,.,H
{hydroxide)
,..,,..-....._a:16
-2.4
alkynes
c=c-H
( alkoxides)
... c=c:
26
(acetylide anions)
-1.7
hych-ogen
H-H
H
I
-1.3
u11111011amia/ines
R...-N•.•,H
3.2
alkanes
4.8
H
:H (hydride) 35
. .__
R.--N. "'H
36
..- (amide bases)
~60
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h\\drogen
1
H
1.0,)79
lthlum
3
ber1IIILm
4
Li Be
5.£41
sodium
11
9.0122
magnesium
12
Na Mg
22.990
pdaislum
19
24.305
calcium
20
K Ca
,9.098
rLbidium
37
40.079
s:rontium
38
Rb Sr
85.468
caesium
55
87.62
Jarium
56
57-70
Cs
13£.9'
frnnclum
87
Ba
13,.33
·00Ium
88
*
89-102
Ra ** Fr
12231
12261
scmdiun
21
lllanlJrr
22
vanajium chromium manganes~ lror
23
24
25
26
Sc Ti V Cr Mn Fe
4l.956
yttrium
39
y
47.e67
zirconium
40
Zr
~0.942
5U96
54938
nobiun 111olybdenumle~hnelum
41
42
43
Nb Mo Tc
55.B45
rutreniun
44
Ru
BS.906
lutetium
71
Lu
91.224
hafnium
72
Hf
£2.906
tantalum
73
Ta
95.94
lun~slen
w74
1981
rhenium
75
Re
101.07
0s11lum
76
Os
1i'4.97
178.49
180.95
183.84
lcwr.mclun rutherfordlJm dubnlum seaborgum
103 104 105 106
183.21
bohrlum
107
180.23
hasslum
108
Lr Rf Db Sg Bh Hs
12621
12611
12621
12661
l'.il34'
12691
boron
5
carron
6
ni:ro;ien
7
BCN
1C.B11
aumin um
13
Al
12.011
s\\icon
14
Si
14.007
fhosphorus
15
p
aibalt
27
nickel
co~per
znc
28
29
30
2e.9a2
g.Jllum
31
28.036
31974
germaniu11 arsenic
32
33
Co Ni Cu Zn Ga Ge As
SS.ffi3
rh:xli.Jrr
45
58.693
palladiu11
46
63.;.iG
silver
47
GE.39
cadmium
48
6£.723
indiu11
49
72.61
tin
50
74.922
antirrony
51
Rh Pd Ag Cd In Sn Sb
102.91
irdium
77
106.4,
platinum
78
'07.8 7
gold
79
112.41
114.82
111ercury lhalllLm
80
81
118.71
ea,j
82
12176
blsrrulh
83
Ir Pt Au Hg Tl Pb Bi
192.22
195.oc
'9f.9!
200.53 2C4.38
mellnerium ununnlllLm un1nun1Jm ununbium
109 110 111 112
Mt UunUuuUub
2072
23898
urunquodium
114
Uuq
12681
·2111
12;21
12771
12891
cxygen
8
0
15.999
sulfur
s16
,2.065
selenlu11
34
Se
78.96
tellu·ium
52
Te
127.60
polonlu11
84
Po
12091
tluorine
9
F
1sgga
chlorlre
17
Cl
35.453
bromine
35
Br
79.904
iocine
53
I
126.91)
aslatlre
85
At
12101
helium
2
He
4.00'6
neon
10
Ne
20.1EO
argo1
18
Ar
39.948
kr,Pton
36
Kr
83.80
xenon
54
Xe
13U9
rado1
86
Rn
1,221
*Lanthanide series
**Actinide series
lnnttm1um
57
La
118.~1
actinium
89
Ac
122,1
cerium p-as~odymiuinr e,dymlurn prJmethlum samanun eu·o~ium Jadolnium
58
59
60
61
62
63
64
Ce Pr Nd Pm Sm Eu Gd
14012
14C.9·
144.24
IW:l
150.36
151.96
157.25
trori.Jrr pro:adinum uranium n~ph.mum pluloniun amerlclu11 curlJrr
90
91
92
93
94
95
96
Th Pa u Np Pu Am Cm
23204
231.04
238.03
1,371
124£1
12431
12£71
tertlum
65
Tb
158.93
berkelium
97
Bk
[2471
d,spuslum
66
Dy
162.50
californum
98
Cf
[251'
1olmlum
67
Ho
164.9~
elns:einlum
99
Es
[25,)
erbium
68
thulium yttenlum
69
70
Er Tm Yb
167.26 168.9~ •7:i.04
fe·mlm rren:leevfum nobelium
100
101 102
Fm Md No
(257)
'2EBJ
[259]
Page 12 of 12