11.3 Alkenes, Set B To print: Ctrl + P, paper A4, margins Default.
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11.3

Alkenes

Set BExam practice
Name
Time 1 hour
Total 24 marks

A Data Booklet may be used.

A

Multiple choice

3 marks
1

CommonCompound S, upon reaction with hot acidified potassium manganate(VII), yields CH3COCH3, CH3COCH2CH2CO2H and HO2CCH2CO2H. A possible structure of S is

ACH3CH=C(CH3)CH2CH2C(CH3)=CHCH2CH2OH
B(CH3)2C=CHCH2CH2C(CH3)=CHCH2CH2OH
C(CH3)2C=CHCH2CH2C(CH2OH)=CHCH2CH3
D(CH3)2C=C(CH3)CH2C(CH3)=CHCH2CH2OH
Answer [1]

Source: SAJC 2007 Prelim P1 Q21, via EJC 2022 JC1 Alkenes Tutorial, Q8

2

Muscalure, a fly sex pheromone, has the structure CH3(CH2)7CH=CH(CH2)12CH3. Which of the following statements about Muscalure is incorrect?

AIn the presence of excess bromine and uv light, it undergoes free radical substitution.
BIt exists as a pair of cis-trans isomers.
CIt gives a diol with cold, alkaline potassium dichromate(VI).
DIt can be extracted from fly paper by soaking the paper in benzene.
Answer [1]

Source: RJC 2007 Prelim P1 Q22, via EJC 2022 JC1 Alkenes Tutorial, Q13

3

Propan-1-ol, CH3CH2CH2OH, is dehydrated by passing its vapour over hot aluminium oxide to give a hydrocarbon. What is the product obtained when the hydrocarbon reacts with bromine?

A1-bromopropane
B2-bromopropane
C1,1-dibromopropane
D1,2-dibromopropane
Answer [1]

Source: A Level 1996 P3 Q21 (modified), via RJC H2 Chemistry Tutorial 12 (Alkenes), Self-check Q3

B

Structured questions

21 marks
4

An alkane B is a component of petrol. When treated with bromine in the presence of uv light, it produces a mixture of brominated compounds, including C, C6H12Br2. Dehydrobromination of C produces D, C6H10. When D is oxidised by hot acidified KMnO4, three compounds, CO2, CH3CO2H and CH3COCO2H, are formed in equimolar amounts.

(a)
Suggest the reagents and conditions for the conversion of C to D.
[1]
(b)
Suggest a structure for compound D, and hence deduce the structure of compound B.
[2]
(c)
There are four possible isomers of C6H12Br2 that could give D on dehydrobromination. Draw the structures of two of them.
[2]
(d)
Suggest, with a reason, the number of stereoisomers of compound D and draw the structural formulae of its stereoisomers. Explain why such isomerism is not possible with cyclohexene.
[4]

Source: EJC 2022 JC1 Alkenes Tutorial, Q4

5

CommonHex-3-ene occurs in two isomeric forms but cyclohexene occurs only in one form.

(a)
Explain why such isomerism is not possible with cyclohexene.
[2]
(b)
Explain why the reaction of either isomer of hex-3-ene with hydrogen bromide gives the same equimolar (1 : 1) mixture of two isomers of the product.
[2]
(c)
The compound hex-3-en-1-ol, CH3CH2CH=CHCH2CH2OH, has a strong "leafy" smell. Suggest the structural formulae of the compounds produced when hex-3-en-1-ol is treated with an excess of hot concentrated KMnO4 in acid solution.
[2]

Source: A Level 2000 P1 Q6, via RJC H2 Chemistry Tutorial 12 (Alkenes), Discussion Q4(a), (c) and (d) (adapted)

6

ChallengeSuggest suitable reagents and conditions to carry out the conversions given below. Give the equation for each step.

(a)
propene → propan-2-ol (in two steps)
[2]
(b)
2-chloropropane → 1,2-dibromopropane
[2]
(c)
butan-1-ol → butan-2-ol
[2]

Source: RJC H2 Chemistry Tutorial 12 (Alkenes), Discussion Q2