rI'IHITIIBIH UI'IIVERSITY

0F SCIEITCE HUD 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 2017 PAPER: THEORY

DURATION: 3 HOURS MARKS: 100

SECOND OPPORTUNITY/SUPPLEMENTARY EXAMINATION QUESTION PAPER

EXAMINER(S) DR. MARIUS MUTORWA

MODERATOR: PROF. HABAU KA KWAAMBWA

INSTRUCTIONS

Answer ALL the questions.

Write clearly and neatly.

Number the answers clearlyPINE"? 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 0F 13 PAGES

(Including this front page, pKa Chart and Periodic Table)

SECTION A [60]

QUESTION 1: Multiple Choice Questions [60]

0 There are 30 multiple choice questions in this section. Each question carries

2 marks.

0 Answer ALL questions by selecting the letter of the correct answer.

0 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.

Hb

Ha/OMCchO

A. Ha; Hb; Hc

B. Hb; HC; Ha

C. Hc; Ha; Hb

D. Hb; Ha; Hc

1.2 List the following compounds in the order of increasing acidity.

O O

A_ /\ B, )LOH c. CH30H D. FQLOH

A. A; B; C; D

B. A; C; B; D

C. A; C; D; B

D. D; C; A; B

1.3 Which of the following is a true statement?

All chiral molecules possess a plane of symmetry

All achiral molecules are meso

All molecules which possess a single chirality center of the 5 configuration are levorotatory.

A mixture of achiral compounds will be optically inactive.F1909“? All molecules which possess two or more chirality centers will be chiral.

Page 2 of 13

1.4 Which of the following species is the strongest base?

A. NHz’

B. CH

C. 0'

D. l'

1.5 Does the equilibrium of this reaction lie to the left or right?

0 O

(E) _

o + CH3OH _ OH + CH30‘—

A. Left

B. Right

C. It cannot be determined

D. The forward and reverse reactions are equally favoured.

1.6 The pKa of CH3COOH is 4.8 and the pKa of HCOOH is 3.8. Given this information, one knows

that

CH3COOH completely ionizes in water

HCOOH is a weaker acid than CH3COOH

HCOO- is a weaker base than CH3COO-

CH3COOH reacts with HO- while HCOOH does not

HCOOH reacts with HO' while CH3COOH does not”POP”?1.7 H-A is an acid with a pKa of 4.5. Which of the following statements about an aqueous solution

of H-A is true?

At pH = 4.5, the solution contains much more H-A than A-

At pH = 4.5, the solution contains much more A' than H-A

At pH- 3.5, the solution contains about 90% A- and 10% H-A

At pH = 6.5, the solution contains about 80% A' and 20% H'A

At pH = 5.5, the solution contains about 90% A' and 10% H-AF1

U

s1

P3

P

1.8 Identify the following compounds as R or 5.

Br H O CH2CH5

l //F——c——Cm

cm——f——m——c——F

Cl 0H 0H éHBPage 3 of 13

in.“ :05"

monw> 1"?” Mm ”MC/1U)”3° 2°

1.9 How many stereogenic centres does the addictive drug heroin have?

.005»? \lO‘U‘l-fi

CH3000

CHgooo‘“heroin

addicting drug

1.10 In question 1.9 above, how many stereoisomers are possible for the drug heroin?

A

B 16

C. 32

D. 64

1.11 Which compound would you predict to be highest in energy?

Cl

A.A

B.B

C.C

DB

——>

step 1

Cl

step 3

OH

A+ HCI

Page 4 of 13

1.12 In question 1.11 above, what kind of reaction does the conversion of A to D represent?

A. Addition

B. Elimination

C. Subtraction

D. Substitution

1.13 Consider the three isomeric alkanes n-hexane, 2, 3-dimethylbutane, and Z-methylpentane.

Which of the following correctly lists these compounds in order of increasing boiling point?

2, 3-dimethylbutane < 2-methylpentane < n-hexane

Z-methylpentane < n-hexane < 2, 3-dimethylbutane

2-methylpentane < 2, 3-dimethylbutane < n-hexane

n-hexane < 2-methylpentane < 2, 3-dimethylbutaneP199095? n—hexane < 2, 3-dimethylbutane < 2-methylpentane

1.14 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.mposw? anti only

1.15 Which of the following compounds is most likely to show first-order kinetics in a substitution

reaction?

Br

OA/Br

0kBr

mBr

0XA B C D

A.A

B.B

CC

0.0

1.16 Given the following substitution reaction, what would the effect be of changing the solvent

from ethanol to DMSO?

CH3(CH2)5BF + NaOH ——>CH3(CH2)5OH + Bl’

Page 5 of 13

A. The rate would increase because 5N2 reactions favour a polar aprotic solvent

B. The rate would decrease because 5N1 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

1.17 Which of the following anions is the best leaving group?

A) NHz— B) Cl" C) CH3" D) OH

A.A

B.B

C.C

D.D

1.18 Which of the following compounds will react most rapidly with HCl?

W909”?S-methyl-l-hexene

4—methyl-1-hexene

(E)~5—methyl-2-hexene

(E)-2—methy|-3-hexene

2-methyl—2—hexene

1.19 For an endergonic reaction step, the Hammond postulate allows one to say that

W909”?the transition state of the step resembles the reactants of the step

the transition state of the step resembles the products of the step

the step is rate-determining since it has the smallest Ea

the reaction containing this step is overall first order

the transition state is precisely symmetric with bond-breaking and bond-forming occurringto the same extent

1.20 Which of the following is the strongest nucleophile in polar protic solvents?

A) IT B) CH3O‘ C) HO— D) CHgs'

A.A

B.B

C.C

D.D

Page 6 of 13

1.21 What is the major product from the acid-catalyzed hydration of 2—methyI—2-pentene?

2-methylpentane

2-methyl-1-pentanol

2-methyl-2-pentanol

2-methyl-3—pentanolF1909”? 1-methoxypentane

1.22 Give the product for the reaction of l-butene with methanol in the presence of acid.

1-ethoxybutane

2-ethoxybutane

1—methoxybutane

2-methoxybutane1119095? 1—butanol

1.23 Which of the following carbocations is the most stable?

++

+ +

A B C D

A.A

B.B

C.C

D.D

1.24 Which alkyl halide (A-C) would give the alkene Y as the only product in an elimination

reaction?

Cl

A B C Y

A. A

B. B

C. C

D. Aand B

Page 7 of 13

1.25 What is the IUPAC name for the following compound?

H H

\ /c=c H

CH3 c=c

H CH2CH3

cis, trans-2, 4—heptadiene

22,4Z—2, 4—heptadiene

cis, cis-2, 4—heptadiene

trans, trans-2, 4—heptadiene

2E,4E-2, 4—heptadieneW909”?1.26 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

1.27 Assuming no other changes, what is the effect of doubling both the alkyl halide and the

nucleophile concentrations in a 5N2 reaction?

A. no change

doubles the rate

triples the rate

quadruples the rate

rate is halvedwoos”1.28 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—ch|oro-2—ethy|—4—methy|—2-pentene

C. (Z)—1-bromo-1—chloro-Z-ethyl—4-methyl-l-pentene

D. (E)-1-bromo-1-chloro-2-ethyI-4—methyl-1—pentene

Page 8 of 13

1.29 Which of the following reaction conditions would result in the anti-Markovnikov addition to

the alkene?

A) H20/H+ B) HBr C) HC] D) [1]BH3; [2] H202/0H_

1.30 Give the IUPAC name of the following compound.

CH3C(CH3)2CH2CECCHgCH(CHgCH2CI-I3)CH3

A. 2,2,7-trimethyI—4-nonyne

B. 2,2,7-trimethyI—4-decyne

C. 3,3,7-trimethyl-4-decyne

D. 2,2,6-trimethyl-4-undecyne

Page 9 of 13

SECTION B: [0]

QUESTION 2 [10]

What is (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 onlya) "Br + CHSOH ——-————>

b) Br +

X—>—

Br _

NH2—____’_

c)-

Br(2 equwalents)

1) 8H3——>

d) W2, HZOZIOH'

H2

__ ————>

Lindlar's catalyst

Page 10 of 13

QUESTION 3 [10]

Determine the reagents required to achieve each of the following transformations.

Note: Each question carries 2 marks.

a) )\/OH —————> /l\/Cl

?Br

b)______>

B

?

a) Q - Q—-——-> Br OH r‘ 0H

? Q

d) ——_—

—-——>\Jk

/7

e) M _—__> A/

QUESTION 4 [10]

Draw a stepwise, detailed mechanism for the following reaction. In order to receive full

marks, show all the electron movement, the intermediates and all the products formed.

‘I

water

__... ?

QUESTION 5 [1 0]

Draw a stepwise, detailed mechanism for the following reaction. In order to receive full

marks, show all the electron movement; draw all the intermediates and all the products.

Hint: The reaction produces two alkene products

CH3“CI ‘OH

———>

THE END

GOODLUCK

Page 11 of 13

pKaChart

con'uoatebase

con'u

ate

base

sulfuricacid

H2804

,

HSO4_

_10

hydrogencyanide

H—CENi—pTCEN:

9-1

(cyanide)

hydroiodicacid

H!

—iI-v

[‘

-9

-

-

.

-,—

9H

.0.-

_

.

_

phenols

—>-

10

hydrobronncac1d

HBr

—>-

Br

-8

hych‘ochloficacid

H01:

"

:91:

—7

water

J'OiH

—>-

—:b'—H

15.7

(hydroxide)

cai‘bocationsM

__,_

/

_3

primaryalcohols

/\

x

H

—D-

A5:—

16

.

‘

Dioxides)

piotonated

_

V

H

H

(1

alcohol

/\O+

/\6’

_2'4

I

"

alkynes

CEO—H

—I~

CEO?

26

(acetylideanions)

H

.

.

Ej

+

.

.

hydroniunl1011

H

’l

N

-

H

H

—>

H,.0,~.H

—1-7

hydrogen

H—H

*—

=H_

amide)

35

.q

mlnlonian’amines

R’.

.\

H

—I-

R/D's-

H

36

'hych‘ofluoricacid

HF

——>

F“

(amidebases)

:0:

:0:

alkanes

fl

4—

A1—

~60

carboxylicacids

/IJ\.O.,H

—"

/”\..—

4.8

H

O.

.0

II

nitricacid

HNO3

——D-No;

—1.3"3m

hydrcgen

1 H1

.0679 ltthlum

belylllJm

Li

Be

6.941

9.3122

sadiJm

magwslum11 Na

Mg

22.990

21-3305

helurr 2 He 4.0026

D0101 5 B 10811

canon G C 12.31‘

nltrogen 7 N 14.007

oxygen 8 O1

5.999

tluorlne 9 F 18998

“16311 Ne 20.180

aluminlurr 13 AI 26.9E2

silicor Si 28.386

phcsphorus 15 P 30.974

sulfur 16 S 32.065

chlarine 1

7

CI 35453

argon 18 Ar 39.948

paiassium

cdclum

KCa 39.1398

40.078

scondlurn 21 Sc 44.956

titan'um 22 Ti 47.867

vanadiJm 23 V 50.942

[71519671659 25 Mn 54.936

‘33 Fe 55.845

cobalt 27 Co 58.933

nlcke 28 Ni 58.693

zin:

gdliu‘n 31 Ga 69.723

gamanium 32 Ge 72.51

arsenlc 33 As 74.922

selen'um 34 Se 78.56

brcmine 35 Br 79.904

krypton 36 Kr 83

80

rubidium

Stmnlum

37 Rb

Sr

85.468

87.62

{MI'UIT 39 Y 88.906

zir:onium 40 Zr 91.224

nioble Nb 92.906

technatlum 43 Tc [93]

rut'tenium

l'hOdiLm 45 Rh 1132.51

pallzdiLm 46 Pd 106.42

indium 49 In 114.E2

2% Sn 118.7’

artln‘ony 51 Sb 12176

telutLIm 52 Te 127.60

lodlne 53 126%

xenon 54 Xe 131.29

caesurn

bariLm

55

565

Cs

Ba

132.91

137.33

lutezlun 71 Lu 174.97

hafnlun' 72 Hf 178.49

tantalum 73 Ta 160.95

rherlun 75 Re '86.21

lridium

77 Ir 192.22

platnu-n 78 Pt 195.08

200.59

thallium 81 TI 204.58

Pb 207.2

b

SfTuli‘ Bi 20898

pobnlurr 84 P0 [209]

astatlne 85 At [210'

[2120n

86 Rn [222]

trandunl

78:111.!“ 88

Fr

Ra

[223]

[226]

18WrenCium

103 Lr [262]

1111118170111[J

m

104 Rf '261]

dubniurn 105 Db [262]

bohrlun 1

07 Bh [2641

melhelium 109 Mt [2681

ununnlllum 110 Uun [271]

ununtzium 112 lUub

*Lanthanideseries

*

*Actinideseries

Jnanuadum 114 Uuq ._L_91_

lanthanum 57 La 1389‘

cerium 58 Ce 14012

pmseadymiurn 59 Pr 140.91

promethIJm 61 Pm [145]

sama'lum 62 Sm 150.36

eurolem 63 Eu 151.96

gadollnlJm Gd 157.25

dysamslurn Dy 152.50

holmlum 67 Ho 164.93

artlum 68 Er 167.26

thullun' 69 Tm 168.93

ytterblurn

70 Yb 173.34

:ctinium 89 Ac 12271

lhor'um 90 Th 23204

plotacthium 91 Pa 231.04

nepthiLm NP [2371

plLlonium 94 Pu 241]

americium 95 Am [2431

cutiun 96 Cm [2471

californium 98 Cf 125H

enszeiriun 99 Es [252]

fermium 100 Fm [2

57]

merdeevurr

101 M [258]

nonelum

102 No [2591

Page13

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