APR 2008

CONFIDENTIAL AS/APR 2008/CHM257

UNIVERSITI TEKNOLOGI MARAFINAL EXAMINATION

COURSE

COURSE CODE

EXAMINATION

TIME

: ORGANIC CHEMISTRY 1

: CHM257

: APRIL 2008

: 3 HOURS

INSTRUCTIONS TO CANDIDATES

1. This question paper consists of three (3) parts : PART A (10 Questions)PART B (10 Questions)PART C (4 Questions)

2. Answer ALL questions from all three (3) parts.

i) Answer PART A in the Objective Answer Sheet.ii) Answer PART B and PART C in the Answer Booklet. For PART C start each

answer on a new page.

3. Do not bring any material into the examination room unless permission is given by theinvigilator.

4. Please check to make sure that this examination pack consists of:

i) the Question Paperii) an Answer Booklet - provided by the Facultyiii) an Objective Answer Sheet - provided by the Faculty

DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO

This examination paper consists of 9 printed pages© Hak Cipta Universiti Teknologi MARA CONFIDENTIAL

CONFIDENTIAL 2 AS/APR 2008/CHM257

PART A

The carbon-carbon sigma bond in ethane is formed by overlap of which two orbitals?

A. 2sp-2pB. sp-spC. sp2-sp1

D. sp3-sp3

2. The reaction of propane with chlorine in the presence of UV light is an example of

A. an addition reaction.B. a substitution reaction.C. a hydrolysis reaction.D. a Friedel -Crafts reaction.

3. When 2-butanol is treated with of concentrated sulphuric acid at 180 °C, the structureof main product could be

CH3 CH3

A. C2H5 - CH-O-CH-C2H5

B. CH3CH2COOCH3

C. CH3CH2COCH3

D. CH3CH = CHCH3

4. The rate of the SN1 reaction is the fastest in the hydrolysis of

A. 1-bromopropaneB. 2-bromopropaneC. 1-bromo-2-methylbutaneD. 2-bromo-2-methylpropane

5. Which one of the following pairs of compounds are isomers of each other?

A. CH3CH2OCH2CH3 and CH3CH2CH2CH3

B. CH3CH2CH2OH and CH3CH2OCH2CH3

C. CH3CH2NH2 and CH3NHCH3

D. CH3CH2CHBrCH3 and CH3CHBrCH3

© Hak Cipta Universiti Teknologi MARA CONFIDENTIAL


6. Which of the following statements is TRUE?

A. Achiral refers to isomers that have atoms bonded in the same order, but withdifferent arrangement in space.

B. Stereoisomers are molecules with mirror images that are superimposable.C. Enantiomers are stereoisomers that are mirror images that cannot be

superimposed on each other.D. Chiral carbon is a carbon that is bonded to two different atoms or groups of

atom

7. Which of the following is not a characteristic of an electrophile?

A. It is a Lewis acid.B. It is a Lewis base.C. It is an electron acceptor.D. It is positively charged

8. Nitration of benzene is carried out using nitric acid and sulfuric acid. The function ofNO2

+ as a/an

A. catalystB. reducing agentC. nucleophileD. electrophile

9. Which of the following is a tertiary haloalkane?

A. C6H5CIB. CH3C(CH3)(CI)(CH3)C. CH3CH(CI)CH3

D. CH3CH(CH2CI)CH3

10.HgSO4 X

ketoH- -C=C—R + H2O

Process X is known as

A.B.C.D.

hydrationpolymerizationhydrolysistautomerization

HgSO4

H2SO4enol



PARTB

QUESTION 1

a) List the following carbonium ions in order of increasing stability.

+

CH3-CH2-CH-CH3 ] CH3CH2CH2 I CH3-C-CH3 ] CH3+

CH3

b) Give two major resources of alkane.

QUESTION 2

Give the IUPAC name for each of the following organic compounds.

a)

b))H

QUESTION 3

Draw the structural formula for each of the following compounds:

a) 4-ethyl-1,2-dimethylcyclohexane

b) 4-isopropyloctyne

(4 marks)

(4 marks)

(4 marks)



QUESTION 4

Classify the following P,Q,R and S reaction

a)

b)

c)

d)

H2SO4P • + H2O

+ H2 (Lindlar catalyst)

Cl2

uv light

H2O(H2SO4 +HgSO4)

C2H5CI

•> Q

• R

(4 marks)

QUESTION 5

Give an appropriate reagents and conditions to prepare each of the following compoundsfrom butyne

a) butane

b) 2,2-dibromobutane

QUESTION 6

Consider the following reaction

(4 marks)

B r "O(CH3)3

f-butanol

a) What is the type of mechanism involved in the reaction?

b) What happen to the reaction rate with each of the following changes?

i) The concentration of "O(CH3)3 is decreased.ii) The halide is changed to CH3CH2CH2CH2CH(Br)CH3.iii) The leaving group is changed to I".

(4 marks)



QUESTION 7

Consider the following bromination reaction

(CH3)3CH + Br2 uv (CH3)3CBr HBr

Write a stepwise mechanism for the reaction including initiation, propagation and terminationsteps.

(4 marks)

QUESTION 8

Identify the reagent needed to carry out each transformation for A and B

B

(4 marks)

QUESTION 9

Compare and contrast reactions between SN1 and SN2 in terms of

a) molecularity

b) reaction mechanism

QUESTION 10

(4 marks)

Predict the major product(s) that would be obtained for the following monosubstitutionreactions.

a) sulfonation of phenol

b) chlorination of benzenesulfonic acid(4 marks)



PARTC

QUESTION 1

In the reaction scheme below, compound V is formed when compound P, C4H8 undergoes Sreaction. Compound P reacts with Br2 in CCI4 to produce compound Q, C4H8Br2. Whencompound P undergoes ozonolysis, compound T and U are the products formed. CompoundP reacts with HBr to produce compound R, C4H9Br (major).

H H H

-C - C - C -

H CH3 H

V

CH3C(CH3)CH2

P

Ozonolysis HBr

Br2, CCU

a)

b)

c)

T + U

Draw the structures of compounds Q, R,T and U

What is the name of reaction S?

C4H9Br (major)R

(4 marks)

(1 mark)

i) What is the functional group of compound P?ii) Which reagent in the above scheme can be used as an indicative test for the

presence of the functional group of compound P? What is the positive resultthat should be observed?

(3 marks)

d) There are two possible products from reaction of compound P with HBr.

i) What rule do you have to apply to get compound R as the only observedproduct?

ii) What is the other possible product that is not observed?(2 marks)



QUESTION 2

a) Under different experimental conditions, chlorine reacts with toluene to giveo-chlorotoluene and benzyl chloride (C6H5CH2CI) respectively.

i) State clearly the different experimental conditions for the above two reactionsii) The reactions undergo different mechanisms. Name the mechanism for each

reaction above,iii) Give equations to show clearly the mechanism involved in the formation of

o-chlorotoluene.(7 marks)

b) Show how the following compounds can be prepared from benzene.

NH2

(3 marks)

QUESTION 3

a) Cow's milk contains about 4% of lactose. Lactic acid is produced by the fermentationof lactose by certain bacteria and is found in sour milk. The acid has the structuralformula : CH3CH(OH)COOH

i) Explain why lactic acid produced from cow's milk has optical activity.ii) Draw the three-dimentional representations of lactic acid and its isomers to

explain the optical activity,iii) Amino acids are acids that contain the -NH2 and COOH groups. Write the

structural formula of an amino acid that shows optical activity and alsoanother amino acid that does not show optical activity

(6 marks)

b) By using equations show how cyclopentane can be prepared from

i) cyclopenteneii) a suitable Grignard reagent

(4 marks)



QUESTION 4

a) Write the structural formula for each of the following alkyl halides.

i) Isobutyl bromideii) 1-Methylcyclopentyl iodideiii) 1-Bromo-2,2-dimethylpropaneiv) terf-Butyl iodide

(4 marks)

b) Draw the structure of the major product of the following reactions. State themechanism (E1, E2, SN1 or SN2) for each reaction.

ethanoli) CH3CH(CH3)CH(CI)CH3 + NaOH • ?

O

ii) BrCH2CH(CH3)CH(CH3)2 + 3 DMF ?•

(4 marks)

c) Give 2 usages of alkyl halides(2 marks)

END OF QUESTION PAPER


APR 2008

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