Alkenes WS

Which of the bonds in the structure below has the lowest bond energy?

F

H A

C B

H

C

C

D

Cl

ALKENES WS 3 H H SECTION A

10 28 Which isomer of C5H11OH gives, on dehydration, the greatest number of different alkenes?

①

A

CH3

CH2

CH

CH2OH

CH3

③ ②

B

CH3

CH2

CH2 CH

CH3

OH C

CH3

CH2

CH

CH2 CH3

OH

①

D

CH3

CH

CH2 CH2OH

(B) CHgatiatatft-43

transport-tell

part-here, oispent-zone, + transport-2-tree.

aspent-z-ere CHz-CH-CH#Hz

→

kHz

CH3

-

onealkere.

CHz-CHECH-CHz but-here.

→

o n e a l l u r e [N'04 Q27]

CHgatiatoatIHz p e n t - t - e re

29 The solvent methylisobutylketone, MIBK, can be made from propanone.

OH

→

H

↳ afgatzateat-4+3 H

t o t a l : 3a l ke n e s .

C

H H

O

H

C

C

H

C

C

H

C

H H

↳

H

H

makes cis-trans

isomers.

cH i s p e n t - 2 - e n e

↳transport-2-ere

Which reagent could distinguish this compound from an aldehyde?

-

A Br (aq) (C) CHECHEITICHECH3 → B 2,4-dinitrophenylhydrazine 2

Saneavene

C

NaBH4

D

Tollens’ reagent

z

isomers

ritzat3

at've I

 UCLES 2004

A

CHzutschatzeltz pent-2-the

T t

c i s pent-2-w e

Alkenes-from-Alcohols-Mcq-Solutions

h a s

p e n t - 2 -e v e

butastrans.

CHECHECHIH-243

par t-2-the

µ,c=V"

Atm 9701/01/O/N/04

'cazutb transport-2-90' 1 of 6

8 14 24 Compound X on reaction with hot concentrated sulphuric acid gave a mixture of three alkenes.

-

OA

butan-2-ol -

B

propan-2-ol

C

2-methylbutan-2-ol

D

3 .

-20

2-methylpropan-2-ol

OH

①

-

-

(A)

CHz-q-CHs

①

-

DO

fH3

What could X be?

[N'05 Q24]

25 Compounds X, Y and Z all react with PCl5 to release hydrogen chloride, but only one of them reacts with 2,4-dinitrophenylhydrazine reagent.

cttz-atz-qyj-4tz-satz-cltzCH-CHzbnt-l-ene.CH, Which one of the following combinations could be X, Y and Z ?

X

A

Y

Z

CH2OH

CHO

CO2H

CH2OH

CHO

CO2H

CH2OH

CH2OH

CHO

CH2OH

CHO

CO2H

CH2OH

CH2OH

CHO

CHO

CO2H

CO2H

-at-CH-CHs

c i s b u t - 2 - s m t - 2 . i e .

B

C

CH,-cH=CHz.

BO atz-GH-ut, CHO CO H→ CH OH D 2

OH

CO2H

2

CO2H

CO2H

CH3

26 In 1903 Arthur Lapworth became the first chemist to investigate a reaction mechanism. The reaction he investigated was that of hydrogen cyanide with propanone.

CHB

(C)

A

CHgatz-d, - 9 + 3

B

electrophilic substitution

C

nucleophilic addition

D

nucleophilic substitution

What do we now call the mechanism of this reaction?

→

CHgatz-deatz

electrophilic addition

OH

2 -

↳

↳

methylb a t - l - e n l ' CHz

43-442-41=450brand. b u t -1 '

2 - methyl

feltz

city-at-C-CHz © UCLES 2005

but-2-enl 2 -methyl

Alkenes-from-Alcohols-Mcq-Solutions

9701/01/O/N/05

Noeisroms.

2 of 6

9 27 24 Which sequence of reagents may be used in the laboratory to convert propan-1-ol into

2-bromopropane?

A

OB

concentrated sulfuric acid, followed by bromine concentrated sulfuric acid, followed by hydrogen bromide

C

ethanolic sodium hydroxide, followed by bromine

D

ethanolic sodium hydroxide, followed by hydrogen bromide [N'10 P12 Q23]

25 A carbanion is an organic ion in which a carbon atom has a negative charge. A carbocation is an organic ion in which a carbon atom has a positive charge.

What is involved in the mechanism of the reaction between aqueous sodium hydroxide and 2-bromo-2-methylbutane?

CltztHz-CHzott → attack by C heterolytic bond fission followed by an an electrophile H E ConHa carbanion #Hz

A B

heterolytic bond fission followed by an attack by a nucleophile on a carbocation

C

homolytic bond fission followed by an attack by an electrophile on a carbanion

D

homolytic bond fission followed by an attack by a nucleophile on a carbocation

I

26 Which compound gives an organic product with a lower boiling point when it is heated under reflux with an excess of acidified potassium dichromate(VI)?

A

2-methylbutan-1-ol

B

2-methylbutan-2-ol

C

pentan-1-ol

D

pentan-2-ol

CHz-GH-CH, B r

27 Use of the Data Booklet is relevant to this question.

Which volume of oxygen, at room temperature and pressure, is needed for complete combustion of 0.1 mol of ethanol?

A

7.2 dm3

B

8.4 dm3

Š UCLES 2013

Alkenes-from-Alcohols-Mcq-Solutions

C

14.4 dm3

9701/13/M/J/13

D

16.8 dm3

[Turn over

3 of 6

B

neither X nor Y

C

X only

D

Y only

29 25 Which isomer of C6H13OH gives the greatest number of different alkenes when it is dehydrated?

A

①

CH3 CH3

CH

B

CH

CH2OH

.

CH 3

CH2

CH2

CH

CH3 D

CH2

C

CH2

CH3

CH3

OH

013'

CH3

to

CH3

CH3 CH3

CH2

OH

¥

C

40

C

CH2

CH2OH

CH3 [J'11 P11 Q25]

hey-3-eve

CHzatz-42%1-41543

cage#CH-CH-CHzCHz

→

CHzatz-CHz-CHIH-CHz © UCLES 2011

both h ex- 2 - e w s o there

h e x - 2 -e r e

9701/11/M/J/11

§

hey-3-e w e

four

will b e

one,

c i shex-2-

c i s hex-3-o n e ,

will has

a

trans

isomers.

a l ke n e s .

transhex-2-ene, t r a n sh e x-z- e n e .

#

(C) a t ,- a t =EI%HzCHz cis

cHztH5§¥CHzcH 'q 3

'gtrans but-2-one

c i s - 2 -ethyl

'q trans-2-ethyl but-24hL

Alkenes-from-Alcohols-Mcq-Solutions

No

cisterns.

2 -ethylb u t - h e r e 4 of 6

What could be the skeletal formula of compound Y? B

A Br

C

D Cl

I

Cl

38 25 The compound shown is menthol, a naturally-occurring alcohol found in peppermint oil.

I

1

Q

G

OH

h

DD

h

menthol

When menthol is heated with concentrated sulfuric acid it reacts. The products that form include compound T. What could be the structure of compound T?

A

B

C

O

D

O [J'13 P12 Q25]

Š UCLES 2013

Alkenes-from-Alcohols-Mcq-Solutions

9701/12/M/J/13

[Turn over

5 of 6

10 42 25 What are the only structures formed when butan-2-ol is heated with concentrated H2SO4?

-

H

CH3CH2 A

C

C

H

✓

C

C

CH3

CH3 C

C

H

C

C

H

H

CH3

H

H

H

H

C

C

CH3CH2

H

CH3

CH3

H

CH3CH2

C

C

CH3

C

C

CH3CH2

H

untiere

C CH3

H

H

H C

C

H

H

H

H

H

C

D

CH3

transtout-z-ere

Cis b u t - 2 - e n l C

C

H

H

CH3

B

H

CH3

C

CH3

H

CH3 [N'13 P11 Q25]

26 How many moles of hydrogen, H2, are evolved when an excess of sodium metal is added to one mole of citric acid?

CHz-CHs-GH-CHz

CO2H

OH

A

1

I

HO

CH2CO2H

C

↳

CH2CO2H citric acid

B

2

C

3

CHz-CHECH-4+3

CHzCHz-CH=CHz D

4

but-here

b u t - 2 - e ve h a s cistrars. © UCLES 2013

Alkenes-from-Alcohols-Mcq-Solutions

9701/11/O/N/13

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