mechanism of organic reactions - coach me€¦ · chemical reactions of organic chemistry and...

(i)

By

AJNISH GUPTA & BHARTI GUPTAProfessor of Organic Chemistry

OrganicFor world of competitions

Mechanism of

Reactions

(ii)

All rights reserved.No part of this publication may be reproduced, storedin a database or retrieval system, or transmitted in anyform or by any means, electronic, mechanical, photo-copying, recording, or otherwise, without the priorwritten Permission of the writter.

First Indian Reprint, 2015

This edition is manufactured in Indian and isauthorized for sale only in India, Bangladesh, Pakistan,Nepal, Sri Lanka & Maldeves.

Printed & Distributed by:Udaan Classes Pvt. Ltd.Rainbow building, Patna &Madhur SatyapushpaShubhash Nagar, Kota9122057123

Price: Rs. 499/-

Copyright © 2015 by Ajnish Gupta

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PrefaceThe guiding principle in writing this book was to createa textbook for students- a textbook that presents thematerial in a way that they learn to solve all thequestions along with the strategy to approach theproblems.In this book we mixed all our teaching experience of 11years along with theoratical and experimentalknowledge to generate a hand book for all students toreason their way to a solution rather than memorize amultitude of facts, hoping they don’t run out of memory.This book covers mainly 6 units along with 10 testpapers to judge your knowledge which help you to solvechemical reactions of organic chemistry and remove thefever of mechanism of organic reactions.Organic chemistry is very easy and conceptual subjectand need proper understanding of the basics andstretegy to solve the questions in corret manner.This book also covers all the questions of AIEEE,IIT-Mains, IIT-Advanced, AIPMT & other medicalexams from 2000 to 2015.In this book balance has to be achieved between thenumber of questions and the quality of the questions,especially because it is relatively easy to frame a verylarge number of multiple-choice questions and theoryof the subject.We would like to thank the editors and production stafffor their efforts in bringing out the book. Suggestionsfrom readers for the improvement of the book are wel-come.

Ajnish Kumar Gupta & Bharti [email protected]

9122057123

mailto:[email protected]

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AcknowledgementWe are thankful to all the teachers who taught usduring the concept building session of our life speciallyDr. Nizamuddin sir, senior Chandra Vijay Rao and Dr.Vijay Pratima Mittal madam.We have written this book to remove the fever oforganic chemistry from mind of students.We particularly want to thank many wonderful andtalented students whom we have taught over the yearswho in turn taught us how to be a good teacher andhow we can help others.We want to make this book as user friendly as possible,and we will appreciate any comments that will help usto achieve this goal in future editions.Finally, this edition has been presented before you withefforts to make it error free. Any that remain are ourresponsibility; if you find any, please let us know so theycan be corrected in future printing.

Ajnish Gupta & Bharti GuptaProfessors of Organic [email protected]

09122057123

mailto:[email protected]

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Table of ContentsPage No.

Unit 1 : Alkene and Alkynes 01Exercise 01 : Subjective approach 02Answer : Subjective approach 68Exercise 02 : Objective approach 08

Single correct questions (SCQ) 08Multiple correct questions (MCQ) 41Assertion/reason type questions (A/R) 50Match the column type ques. (MTC) 52Comprehension type questions 54Integer type questions 59

Answer : Objective approach 81Exercise 03 : World of competition 60Answer : World of competition 83

Unit 2 : Oxidation, Reduction & Alkane 84Exercise 01 : Subjective approach 85Answer : Subjective approach 143Exercise 02 : Objective approach 92


Answer : Objective approach 154

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Exercise 03 : World of competition 129Answer : World of competition 156

Unit 3 : Aromatic compounds 157Exercise 01 : Subjective approach 158Answer : Subjective approach 242Exercise 02 : Objective approach 172


Answer : Objective approach 268Exercise 03 : World of competition 210Answer : World of competition 270Test-1 : Hydrocarbon & Benzene derivatives 272Answer : Test-1 282

Unit 4 : Alkyl halide, alcohol & ether 283Exercise 01 : Subjective approach 284Answer : Subjective approach 385Exercise 02 : Objective approach 290


Answer : Objective approach 397

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Exercise 03 : World of competition 360Answer : World of competition 400Test-2 : Alkyl halide, alcohol & ether 402Answer : Test-2 413

Unit 5 : Aldehyde, Ketone, Carboxylic acidand Derivatives 414

Exercise 01 : Subjective approach 415Answer : Subjective approach 484Exercise 02 : Objective approach 424


Answer : Objective approach 507Exercise 03 : World of competition 461Answer : World of competition 509Test-3 : Aldehyde, Ketone, Carboxylic acid

and Derivatives 510Answer : Test-3 521

Unit 6 : Biomolecules, Polymer, POC andPhysical properties 522

Exercise 01 : Subjective approach 523Answer : Subjective approach 578Exercise 02 : Objective approach 525

Single correct questions (SCQ) 525Multiple correct questions (MCQ) 540

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Assertion/reason type questions (A/R) 545Match the column type ques. (MTC) 547Comprehension type questions 549Integer type questions 551

Answer : Objective approach 588Exercise 03 : World of competition 554Answer : World of competition 590Test-4 : Biomolecules 592Test-5 : Reduction, Oxidation, Hydrocarbon, &

Derivative, Alkyl halide alcohol & Ether 603Test-6 : Reduction, Oxidation, Hydrocarbon &

Derivative, Alkyl halide alcohol & Ether 613Test-7 : Aldehyde, Ketone, Carboxylic acid

and Derivatives 624Test-8 : Mixing of chapters in organic reactions 635Answer : Test-4, 5, 6, 7, 8 645

Organic Chemistry is easyby

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1Organic Chemistry is easy bywww.CoachMe.co.in

Alkene & Alkyne

This unit give you an understanding of “GeneralOrganic chemistry of alkene & Alkyne” and coversfollowing topics: Reaction of HX Reaction of H2O/H+

Reaction of ROH/H+

Reaction of X2

Reaction of X-X’ Reaction of NOX Reaction of HOX Oximercuration-Demercuration Alkoxymercuration-Demercuration Hydroboration-Oxidation

Objective

1Unit

Alkene and Alkynes

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Organic Chemistry is easy bywww.CoachMe.co.in

2

Alkene & Alkyne

You can’t learn organic chemistry because there’s too much ofit. You can learn trivial things like name of compounds but thatdoesn’t help you to understand the principle behind the subject.You have to understand the principle because the only way totackle organic chemistry is to learn to work it out. That is why weare first providing you some questions so that your understandingabout the topic should be increased. These problems should be setyou on your way but they are not the end of the journey as youbegin your journey to understand organic chemistry.

The problem would be of little use to you when you could notcheck your answers. For the maximum benefit, you need to solveall the problems without looking the answers. Then you shouldcompare your answers or suggestions with ours before going tonext chapter. If any answer is mismatch then darken those questionnumbers with red pen and again have a micorscopic look over itand its theory and correct it before proceeding further. Here startsthe first set of 55 questions1. What are the general types of organic reactions. Comment over

it by taking simple alphabets without any reaction.2. What is reagent. Name the types of reagent generally we

encounter in organic chemistry.

01Exercise

Subjective Approach

http://www.CoachMe.co.in2


Alkene & Alkyne3. What is an electrophile and what are the factors which

increases the electrophilic nature of any molecule.4. What is nucleophile and what are the factors which Increases

the nucleophilic character of any molecule.5. What is free radical and what are the factors which increases

the free radical formation easy in any molecule.6. What is leaving group and what are the factors which increases

the leaving group character of any species.7. Write the order of nucleophilic character in given molecule.

– – – –3 3OH , Ph–O , CH –C–O , CH –S–O

O

O

O

– – – –I , Br , Cl , F3 2NH , H O

8. Write in decreasing order of leaving group character in givenmolecules.

– – – –3 3OH , Ph–O , CH –C–O , CH –S–O

O

O

O

– – – –I , Br , Cl , F 3 2NH , H O

9. What are solvents. How they are classified. Write example ofeach types.

10. What is the basic difference between base, nucleophile andligand. Explain with example.

11. What is the general chemical reaction of alkene & alkyne.12. What is Markownikoff rule.13. What is the basic concept behind Markownikoff rule. Give an

example which violate this rule.14. Write 2 chemical test which can distinguish alkene from alkanes.15. What is Baeyer’s reagent. How is it important in organic

chemistry.16. What is general hydration reaction of alkene. Give the

mechanism of hydration of propene.



4

Alkene & Alkyne17. What are the three methods by which water is added to alkene.18. What is oximercuration-demercuration. Explain with an

example.19. What is alkoxymercuration-demercuration. Explain with an

example.20. What is hydroboration-oxidation. Explain with an example.21. Comment on the nature of hydroboration-oxidation and state

whether it follows Markownikoff rule or violate it.22. Write the mechanism of bromination of alkene using propene

as substrate.23. What type of change in product is observed when bromination

is carried out in different conditions such as

(A) 42Br / CCl (B) 2 2Br /H O

(C) 2Br / NaCl (D) 2 3Br / CH OH

Write the reaction using propene as substrate.24. Write the reaction as well as mechanism of addition of HBr on

alkene, taking propene as substrate.25. Write the reaction as well as mechanism of addition of HOCl

on alkene, taking propene as a substrate.26. Write the reaction as well as mechanism of addition of ICl on

alkene, taking propene as a substrate.27. Write the major product of following reactions.

+2H O/H

ICl

8 1

2

34

5

6

7HOCl HCl

i 3) BH–

2 2ii) H O /OH2 4Br /CCl

2 2Br /H O

4ii) NaBH2 2ii) (Ac O)Hg/H O



Alkene & Alkyne28. What is Kharasch effect or Anti-Markownikoff rule. Explain

with an example taking propene as a substrate.29. What is NBS. Write the product formed on reaction on propene

with it.30. What is NCS. Write the product formed on reaction of propene

with it.31. What product is obtained when propene is heated with

chlorine at high temperature.32. What will be the major product obtained on reaction of NBS

over following substrate.(A) But-1-ene (B) 3-Methylcyclohexene(C) Penta-1,4-diene (D) Cyclohexa-1,4-diene

33. Write the reaction as well as mechanism of addition of HCl onalkyne.

34. Write the reaction as well as mechanism of addition of HOClon propyne.

35. What will be obtained as a product when propyne undergoeshydroboration-oxidation reaction.

36. How general hydration of alkyne occur. Give reaction as wellas mechanism of it taking propyne as substrate.

37. What is the role of mercury sulphate in hydration reaction ofalkyne along with dilute sulphuric acid.

38. What will be the major product obtained when compoundhaving conjugation of alkene & alkyne such aspent-1-en-3-yne is treated with 1 eq. of HCl.

39. What will be the major product obtained when compoundhaving double bond & triple bond are not is conjugation suchas pent-1-en-4-yne is treated with 1 eq. of HCl.

40. Why alkenes are generally more reactive than alkyne towardsany electrophilic addition reaction.

41. Why some acids are added to the reaction chamber beforeadding water in the hydration reaction of alkene & alkynes.



6

Alkene & Alkyne42. What is the major product of hydroboration oxidation reaction

of following compounds.

(A) 6

3

3 22

2 2

| i) B H–ii) H O /OH

CH

CH – CH – CH = CH X

(B) 6

3

32

2 2

| i) B H–ii) H O /OH

CH

CH – CH – C CH Y

43. What is the major product of oximercuration-demercurationof following compounds.

(A)4

3

3 222

| i)(Ac O)Hg/H Oii)NaBH

CH

CH – CH – CH = CH X

(B)4

3

322

| i)(Ac O)Hg/H Oii)NaBH

CH

CH – CH – C CH Y

44. Write the product of bromination in different condition.

2 4Br /CCl

2 2Br /H O

2 3Br /CH OH

2Br /NaCl

M

N

O

P45. Write the major product of following reaction.

2 6i) B H–

2 2ii) H O /OH2 6i) B H

3ii) CH COOH

2Br

ICl

HCl

HOCl + 2+2H O/H /Hg

i i) NaB

H 4

i) (Ac O)H

g/H

O

2

21 2

3

456

7

8

46. How terminal alkyne is distinguish from non-terminal alkynes.



Alkene & Alkyne47. What product will be formed when acetylene (HC CH) is

heated with Fe?48. Why the acid catalysed hydration of following alkene follows

the same order as that of stability of it. > >

49. Why electrophilic addition of 1,3-Butadiene is faster than thatof But-1-ene.

50. Write the structures of total isomers (including stereo) formedwhen one quivalent of HBr is added to Buta-1,3-diene.

51. Write the structures of total isomers (excluding stereo) formedwhen one equivalent of HBr is added to Hexa-1,3,5-triene.

52. What will be the product of bromination of following substrate.

(A) NH

(B) OH

(C) O

OH (D) N

H53. What will be the major product of acid hydration in given

compounds.(A) 2 2H C = C = CH (B)

(C)O

(D) O

54. Write the mechanism of following interconversion.

Ph – CH – C CH Ph – CH = CH – C – HOOH

+2H O /H

55. Write the major product of protonation in followingcompounds.

(A)

O

(B) OH (C)HO

(D)

O

PhPh



8

Alkene & Alkyne

Single Correct Questions (SCQ) :

1.2 2CH =CH

I 3 2CH –O–CH=CH

II3 2CH –CH=CH

III

2Cl–CH=CHIV

2OHC–CH=CHV

Correct order for electrophilic addition reaction of givencompound follows(A) I > II > III > IV > V (B) II > III > I > IV > V(C) II > IV > III > I > V (D) V > IV > II > III > I

2.

O

I

II

O

III

IV

Cl

3CH

VCorrect order for electrophilic addition reaction of givencompound follows(A) I > II > III > IV > V (B) III > V > II > IV > I(C) III > IV > V > II > I (D) I > IV > III > II > V

02Exercise

Objective Approach



Alkene & Alkyne

3.

Ph

PhI

Ph–CH=CH–PhII

3Ph–CH=CH–CHIII

3 3CH –CH=CH–CHIV

Correct order for electrophilic addition reaction of givencompound follows(A) I > II > III > IV (B) I > III > II > IV(C) I > II > IV > III (D) II > I > III > IV

4. 2 2H C=CHI

3 2CH –CH=CH

II

3 2|

3

CH –C=CHCHII

3 3| |

3 3

CH –C C–CHCH CH

=

IV

Correct order for electrophilic addition reaction of givencompound follows(A) IV > III > II > I (B) I > II > III > IV(C) III > IV > II > I (D) IV > II > I > III

5. 3CH 2CH=CH

I2CH=CHCl

II

3CH O 2CH=CH

III2CH=CH2O N

IVCorrect order for electrophilic addition reaction of givencompound follows(A) III > I > II > IV (B) IV > II > I > III(C) III > II > I > IV (D) IV > III > II > I

6. IV



10

Alkene & AlkyneCorrect order for electrophilic addition reaction of givencompound follows(A) I > II > III > IV (B) I > II > IV > III(C) II > I > IV > III (D) II > IV > III > I

7. Incorrect order of reactivity towards electrophilic additionreaction of following compound follows(A) Ethene > Propene(B) Methoxyethene > Chloroethene(C) Phenylethene > Cyclohexylethene(D) Ethene > Ethyne

8. 3 2CH –O–CH=CHI II

F–CH=CH2

IIICH –CH=CH3 2

IV

CH=CH2

Rate of hydration of the following alkenes is(A) I > II > III > IV (B) I < II < III < IV(C) I > IV > III > II (D) I > IV > II > III

9. ICH =CH2 2 II

CH =CH–CHO2 III

CH –CH –CH=CH3 2 2 IV

CH –C=CH3 2

CH3

Rate of addition of Cl2 / H2O of the following alkenes is

(A) IV > III > I > II (B) IV > III > II > I(C) I > II > III > IV (D) I > II > IV > III

10. Which of the following reactant is most reactive towardselectrophilic addition reaction with HBr.

(A)Ph Ph

(B)3OCH

(C) PhPh (D)

3CH



Alkene & Alkyne

11. HBr Major product

(A)

CH Br2

(B)

CH3

Br(C)

Br

(D)

CH3

Br

12. HCl Major product

(A)

CH –CH –Cl2 2

(B)Cl–C–CH3

H

(C)

CH –CH2 3Cl

(D)

CH –CH2 3

Cl

13. CH=CH HBr Major product

(A) CH–CH 2

Br(B) CH –CH2

Br

(C) CH=CHBr

(D) CH=CHBr

14. F3C – CH = CH2 + HCl Major product

(A) 3 3F C–C–CHCl

H

(B) F3C – CH2 – CH3

(C) 3 2F C–CH–CHCl Cl

(D) F3CCH2CH2Cl



12

Alkene & Alkyne

15.2CH

HBr X(major product)

X will be

(A)2CH –Br

(B)3CH

Br

(C)3CHBr (D)

3CH

Br

16. Major product X, Y, Z obtained in the following reaction is:HBr

3CH 2H O

2D O

HBr3CH OH

HBr

X

Y

Z

(A) 3CHOH

3CHOD

3CH3OCH

, ,

(B) 3CHOH

3CHOD

3CH3OCH

, ,

(C) 3CHBr

in all reaction

(D) 3CHOH

in all reaction



Alkene & Alkyne17. Which of the following is/are the major product(s) of the

following reaction?

CH= C3CH

HBr ?

(A) CH=CH3CH

Br(B) 2CH –C

3CH

Br

(C)

3CH

Br

CH=C(D) CH=C

3CH

Br

18. In which of the following alkenes will a hydrogen shift occurupon addition of HBr?

(A) (B)

(C) (D)

19. The product of following reaction can be :

3H C 2CH=CHOH HBr

(A)OH3H C

3CH(B) OH

3CH

3CH

(C) O

2CH

3CH

(D)O3H C

3CH



14

Alkene & Alkyne

20. 3HClPh–CH=CH–CH

The major product of given reaction will be

(A)2 3Ph–CH –CH=CH

Cl(B)

2 3Ph–CH–CH –CH

Cl

(C) 3CH=CH–CHCl

(D) 3CH=CH–CHCl

21. HBr3CH

(A) 2CH –Br

(B) 3CH

Br (C)Br

3CH (D)

Br

22.

3CHX

(major product)HCl

(A)

3CH Cl(B)

Cl

(C)Cl

(D)

3CHCl

23.X

(major product)HCl

OHMajor product X will be

(A)Cl

(B) Cl

(C)

Cl

(D)

Cl



Alkene & Alkyne24. Which of the following reaction results in the formation of pair

of enantiomers on treatment with HBr

(A) (B) (C)O

(D)

25. Which of the following reaction results in the formation of apair of diastereomers on treatment with HBr

(A) (B) Ph

(C) (D)

26. How many transition state and intermediate will be formedduring the course of following reaction.

HBrBr

(A) 3 TS & 3 intermediate (B) 4 TS & 3 intermediate(C) 3 TS & 2 intermediate (D) 3 TS & 4 intermediate

27.

EtMe

HBr

The product(s) of the following reaction can best be(A) A racemic mixture (B) A single enantiomer(C) A pair of diastereomers (D) A single meso compound

28.

Cl

XHCl

The major product ‘X’ in the given reaction will be(A) cis-1,3-Dichlorocyclohexane(B) trans-1,3-Dichlorocyclohexane(C) cis-1,2-Dichlorocyclohexane(D) trans-1,2-Dichlorocyclohexane



16

Alkene & Alkyne29. Which reaction will occur at the fastest rate.

(A) HBr Br(B)

HBr

Br

(C) HBrBr

(D)HBr

Br30. Predict the major product of the reaction of 1,4-pentadiene

with excess HBr.(A) 1,4-dichloropentane (B) 1,5-dichloropentane(C) 2,4-dichloropentane (D) 4-chloro-1-pentene

31. Which energy diagram best describes the electrophilicaddition of HBr to alkenes?

(A) (B) (C) (D)

32. Which reaction has the lowest ΔG or activation energy?

(A) HBr (B) HBr

(C) HBr (D) HBr

33. HCl Cl

The intermediate formed in given reaction will be

(A) . (B) (C) (D) Cl

34. HCl

The carbocation which is not formed at all in given transfor-mation reaction is

(A) (B) (C) (D)



Alkene & Alkyne

35. HCl ?

Which reaction mechanism is most likely to occur during thisreaction.

(A) H +Cl

Cl

(B) H + Cl

Cl

(C) H + ClCl

(D)H + Cl

Cl

36. H+

Which of the following energy profile best represents abovereaction

(A)

Overall reaction

E p(B)

Overall reaction

E p

(C)

Overall reaction

E p(D)

Overall reaction

Ep



18

Alkene & Alkyne37. What is/are the product(s) from the following reaction?

3CHCl3CH3CH+ HCl ? Cl

(I) (II)

(A) I only (B) II only(C) I is minor, II is major (D) I is major, II is minor

38. 2 4dil.H SO

(A) OH (B) OH

(C) OH (D)HO

39. 3CH 2 4

dil.H SOX

(major product)

Major product X is :

(A) 3CHOH

(B)3CH

OH

(C) 3CHOH

(D) 3CHOH

40. CH=CH–CH3

2 4dil.H SOX

(major product)

Major product X will be :

(A) only CH –CH–CH2 3

OH

(B) only CH–CH –CH2 3

OH

(C) (A) and (B) (D)CH –CH –CH2 2 3

OH



Alkene & Alkyne

41. Ph – CH2 – CH = CH2 2 4dil.H SO

(A) 2 3Ph–CH–CH –CHOH

(B) 3Ph–CH–CH–CHOHH

(C) 3Ph–CH–CH–CH

OH OH(D) Ph – CH2 – OH

42. +2H O/H

The intermediate formed in given reaction will be

(A) (B) (C) O

H (D)

OH

43.NO2

2 4dil.H SO

(A) NO2HO (B)

NO2

OH

(C)NO2

OH(D)

NO2HO

44.

3CH3 2CH –CH–CH=CH 2 4dil. H SO

(A)

3CH3 2 3CH –C–CH –CH

OH

(B)

3CH3 3CH –C C–CH

H OH

H

(C)3CH

3 2 2CH –CH–CH –CH –OH(D)

3CH2 3HOCH –CH CH–CH

H



20

Alkene & Alkyne

45. 2Br (X) Product. Value of X is:4CClH

C=CH

3CH 3CH

(A) 0 (B) 1(C) 2 (D) 3

46.H +

X(major product)HO

Major product X will be

(A)3CH (B) O 3CH

(C)OH

(D) OH

47.+

2D O/HX

(major product)

(A)D

OD (B)

H

OD(C)

H

OH (D)

D

OH

48.+

2H O/HX

(major product)

The major product X of the given reaction will be

(A)OH

(B)OH

(C)OH

(D)OH



Alkene & Alkyne49. Which of the following is among the major products of the

reaction of (E)-3-methyl-2-pentene with BH3 in THF followedby the addition of H 2O2//HO– ?

(A) H

OHHEt

MeMe (B) H

OHH

EtMe

Me

(C) H

OHH

EtMe

Me

(D) OH

H

Et

MeH

Me

50. OCH3

(A) CH3OH / H+ (B) CH3CH2OH / H+

(C) H2O / H+ (D) HOCl / H+

51. CH3CH = CHCH3 x

3 2 3CH CHCH CH

2 3OCH CH

x will be :


(C) H2O / H+ (D) HOCl

52.H

C=CH

3CH 3 2 2C(CH ) CH OH 4CCl2Br (A). Product (A) is:

(A) 3CH

3CH O

Br

3CH (B)3CH O

BrH 3CH

3CH

(C) 3CH

O3CH

3CH

Br

H(D)

O Br



22

Alkene & Alkyne

53. H3CH

3(1) BH ;THF–

2 2(2) H O , HO(A); Product of the reaction is:

(A) H

3CHH

OH (B) H

3CH

H

OH(C)

3CH

H

HH (D) H

3CHH

3CH

54.3CH

3H CO

3CH+

3CH OH/HX

(major product)

The major product X will be

(A)3CH

3H CO

3CH3OCH

(B)3OCH

3CH

3H C3OCH

(C) 3OCH3CH

3H C(D)

3OCH3CH

3H CO3CH

55. X(major product)

+3CH OH/H

3Ph–CH=CH–CH


(A)2 3Ph–CH –CH–CH

3OCH (B)2 3Ph–CH–CH –CH

3OCH

(C)2 2 2Ph–CH –CH –CH

3OCH (D) 2 2 3CH –CH –CH3H CO



Alkene & Alkyne56. What is the major product of the following reaction?

3CH

2H O2Br

+ X(major product)


(A)3CH

OHBr (B)

3CHOHBr

(C)3CH

Br (D) 3CH

OH

57. Which reaction intermediate is formed when Br2/CCl4 reactswith cyclohexene?

(A)Br

(B) Br

(C)Br

. (D) Br

58. cis-2-Butene 2 2Br /H O

(A)OHBr3CH

HH

3CH

(B) OH

Br

3CH

HH

3CH

(C) OH

Br3H C

H

3CH

H (D)Br

HO3H C

H

3CH

H

59.H

H

4CCl2Br

Product of above reaction is:

(A) meso (B) racemic mixture(C) diastereomer (D) structural isomer

60. 2Br

(A)Br

Br(B)

Br

Br

(C) Br

Br

(D)BrBr



24

Alkene & Alkyne61. What is/are the product(s) from the following reaction?

2 4+ Br /CCl ?

(I) BrBr

(II)Br

Br

(III)BrBr

(IV)BrBr

(A) I and II (B) I and III (C) I and IV (D) II and III

62. 2BrX

(major product)

N

H


(A)N

H

BrBr (B)

N

Br(C)

N

Br (D)

N

BrBr

Br

63. 2BrX

(major product)

OH


(A) OBr

(B) OHBrBr

(C) OBr

(D) BrO

64. Which compound on reaction with bromine give meso-2,3-Dibromobutane as a product.

(A) (B) (C) (D)



Alkene & Alkyne

65.

Br

2 5C H

3CHH

(Z)4CCl

2Br(stereoisomer)

( )

(A) Br

3CH

Br

2 5C HBrH (B) Br

H3CH

Br

Br5 2H C

(C) Br

3CH

Br

5 2H C BrH (D) Br3H C

Br

5 2H C BrH

66.4CCl

2Br Identify product’s:

(A)Br

EtBr (B)

Br

BrBr

Et

(C)Br

(D)H

BrBr

Et

67. Which of the following is most reactive toward bromination?

(A) 3OCH(B)

Cl

(C) (D)

68. C=CH

H3CH

3CH2Br

4CCl (X) products. Value of X is:

(A) 0 (B) 1 (C) 2 (D) 3



26

Alkene & Alkyne69. Which of the following species is an intermediate in the

reaction shown below?

2 2Br /H O

OH

Br

(A)Br+

(B) O

(C) O+

H(D)

–Br

70.2Br (1 eq) X

(major product)2NH


(A) N

H

Br

(B) N BrH

(C)

Br

2NH(D) Br

Br

2NH

71.2Br (1 eq)

X(major product)OH


(A)OH Br

Br(B)

OH

Br

(C)Br

O(D)

BrO



Alkene & Alkyne

72.2Br

X(major product)

COOH


(A)O

Br

O

(B) O

O

Br

(C)Br

OO

(D)Br

COOH

Br

73.3SO H

2Br X(major product)


(A)S

O O

O

Br(B)

SO

Br

O

O

(C)Br

3SO H

Br (D)Br 3SO H

74.Cl

OH


(C) H2O / H+ (D) HOCl / H+



28

Alkene & Alkyne75. Which statement is correct for iodolactonization reaction

(A) It is the organic reaction that form a lactone by the addi-tion of an oxygen and iodine across a carbon-carbondouble bond.

(B) It is the organic reaction that form acyclic amide by theaddition of an oxygen and iodine across a carbon-carbondouble bond.

(C) It is the organic reaction that form acyclic ester by the ad-dition of an oxygen and iodine arcoss a carbon-carbondouble bond.

(D) It is the organic reaction that form lactum by the additionof an oxygen and iodine arcoss carbon-carbon doublebond.

76. The intermediate formed in halolactonization reaction is(A) Carbocation (B) Cyclic halonium ion(C) Carbanion (D) Free radical

77.3CH 3CH

X(major product)

2 3I /NaHCO

2 2CH Cl

–COO

X (major product)

(A)O

O

2I–H C 3CHH

3CH (B)O

O

2I–CH 3CHH

3CH

(C)O

O

2IH C 3CHH

3CH (D)O

O

2CH I 3CHH

3CH



Alkene & Alkyne78. Which is incorrect among these?

(A)2 3I /NaHCO

3CHCl

COOH

0°C, 6HPh

O

O

Ph I

(B)0°C, 24H

2ICOOH

PhO

O

Ph IMeCN

(C) Formation of cis product is kinetic product while transproduct is thermodynamic product.

(D) Formation of cis product is thermodynamic product whiletrans product is kinetic product.


3i) NaHCO

2ii) I , KI, 0 C°OO

O OH

Major product x will be

(A)OO

O O

I(B)

OI

O

(C)

O OI

(D)OO

O OI


2BrOH 2 2CH Cl


(A) OH

BrBr (B) O Br

(C) O

Br (D) O Br



30

Alkene & Alkyne81. Which will not be the product of given reaction

2 2Br /H OOH

(A) OBr

H(B) O

BrH

(C) OHOH

OH (D) OHOH

Br

82. 2 2i) Hg(OAc) /H O4ii) NaBH The intermediate of reaction will be

(A) (B)

(C)O

3Hg–O–C–CH (D)3HgOCOCH

83. Which of the following statement is wrong aboutoxymercuration-demercuration reaction of alkene.(A) In 1st step, Hg(OAc)2 & H2O adds to C=C double bond.(B) In 2nd step, NaBH4 reduce –HgOAc group & attached H.(C) The net reaction is addition of water according of

markownikoff rule.(D) Carbocation is formed in this reaction.

84.3 2CH –CH–CH=CH

3CH4( ii) NaBH

2 2(i) Hg(OAc) /H O

(A)3CH

OH

3 2 3CH –C–CH –CH(B) 3 3CH –C C–CH

3CH

H

H

OH

(C)3 2 2CH –CH–CH –CH –OH

3CH (D)2 2 3HOCH –CH CH –CH

3CH



Alkene & Alkyne

85. –4(2) NaBH OH+

2 2(1) Hg(OAc) /THF–H O

(A)OH

(B)OH

(C)OH

(D) all of these

86. C–CH=CH2

H

CH3

4(2) NaBH NaOH+

2 3 2 2(1) Hg(O CCH ) , H O

(A) C C – CH3

HCH3

OHH(B) C C – CH3

HCH3

HH

(C) C C – CH3

HCH3

HOH(D) C–C –OHH2

CH3

CH3

87. NaBD4

Hg(OAc) /H O2 2

(A)H

OH

H

D (B)

OH

H

H

D(C)

OH

HD

H(D)

OH

D

88.2i ) Hg (OAc)

X(major product)

OH4ii) NaBH


(A) O (B) O (C) O (D) OHOH



32

Alkene & Alkyne89. Which of the following alkene will give Methylcyclohexanol

on oxymercuration-demercuration reaction.

(A) (B)

(C) (D)

90.

O

X(major product)

2Hg(OAc) /ACOH


(A)

OHgOAc

OAc(B)

O

OAcHgOAc

(C)

O

OAcHgOAc

(D)

O

HgOAc

OAc

91. -(i) BH –THF3

(ii) H O /OH2 2

(A)CH 3

HO(B)

CH3HO

H H

(C)CH3

OHH

H(D) CH3

OH

H

H



Alkene & Alkyne

92. 3 2CH –CH–CH=CH

3CH2 2(ii) H O /OH

3(i) BH –THF

(A) 3 2 3CH –C–CH –CH

3CH

OH

(B) 3 3CH –C C–CH

3CH

H

H

OH

(C)3 2 2CH –CH–CH –CH –OH

3CH (D)2 2 3HOCH –CH CH –CH

3CH

93. Hydroboration oxidation reaction of alkene follows via(A) Formation of 6 membered cyclic tranition state.(B) Formation of 5 membered cyclic transition state.(C) Formation of 4 membered cyclic transition state(D) Formation of 3 membered cyclic transition state

94. (i) BD – THF3

(ii) H O / OH¯2 2

(A)H

OH

H

D(B)

OH

H

H

D

(C)H

OH

H

H(D)

OH

HH

D

95. 3BH , THF–

2 2H O , OH

(A) (B) OH

(C) OH (D)OH



34

Alkene & Alkyne

96.3BD /THF

–2 2H O /OH

X(major product)

X will be

(A) HD

(B) OHD

(C) DOH

(D) HOD

97. OH

OH

OH

X

Y

Z

X, Y, Z reactions are respectively called as(A) All is simply hydration reaction.(B) Acid hydration, Oxymercuration-demercuration,

Hydroboration-oxidation.(C) Acid hydration, Hydroboration-oxidation oxymercuration

demercuration.(D) Oxymercuration-demercuration, Hydroboration-

oxidation, acid hydration.

98. 3 2CH –CH–CH=CH

(A)Br

HBr HBr–20°C 40°C CH –CH=CH–CH –Br3 2

(B)

Both the major product A and B are(A) Kinetically controlled product(B) Thermodynamically controlled product(C) A is thermodynamically controlled & B is Kinetically

controlled.(D) A is kinetically, B is thermodynamically controlled



Alkene & Alkyne

99.HCl (1 eq)

(A)

Cl

(B)

Cl

(C) Cl (D)Cl

100. CH=CH HBr / R O2 2

(A) CH–CH2

Br(B)

Br2CH –CH

(C) CH=CHBr

(D) CH=CHBr

101. What is the major product of the following reaction?

3CHHBr

Peroxide ?

(A) 3CHBr

(B) 2CH Br

(C)3CH

Br(D) 3CH

Br



36

Alkene & Alkyne102. Which of the following is a step in the mechanism of the

reaction shown?

2 3CH =CHCH + HBr 2 2 3CH CH CHPeroxide

Br

(A) 2 3CH CHCH + HBr

Br

.(B) 2 2 3CH CH CH + HBr

.

(C) 2 3CH CHCH + HBr

Br(D) 2 2 3CH CH CH + HBr

103. I – Cl

The intermediate of given reaction will be

(A) I

(B) Cl

(C) Cl (D) I

104. HOCl


(A) O

H(B) Cl

(C) Cl (D) OH

105. NBS


(A) (B) (C) . (D)



Alkene & Alkyne

106. NOCl


(A) NO (B)NO

(C) N

O(D) Cl

107. Cl–CN


(A) Cl (B) CN

(C) Cl (D) N C

108.3 2

NBSCH –CH=CH

(A) 3 2 2CH –CH –CH –Br (B)2 2CH –CH=CH

Br

(C) 3 3CH –CH–CHBr

(D) 3 2CH –CH–CHBr Br

109. trans-2-pentene 2 4Cl /CCl

(A) ClH

2 5C H

HCl

3CH

(B) Cl

2 5C H

H3CH

ClH (C)2 5C HH

3CH

Cl HH

(D) Cl

2 5C HH3CH

Cl H



38

Alkene & Alkyne110. Predict the product of the reaction of 1-pentyne and excess

HCl in the presence of hydrogen peroxide.(A) 1,1-dichloropentane (B) 1,2-dichloropentane(C) 2,2-dichloropentane (D) 2-chloro-1-pentene

111. 3 2CH CHCH CC CH

3CH3CH

OH

4HgSO2 2 4H O.H SO

(A) 3 2CH –CH–CH –C=CH–C–H

3CH3CH

O

(B)3 2 3CH –CH–CH –C C–CH

3CH

OH

3CH

O

(C) 3 2 2CH –CH–CH –C – C=CH

3CH

OH

3CH OH

(D) 3 2CH –CH–CH –C–CH=CH

3CH

OH

3CH OH

112.3 2 2

3 2 2–BH , THF H O /OHCH CH CH C CH

(A) CH3CH2CH2CH2 – CHO (B)O

3 2 2 2CH CH CH CCH

(C) CH3CH2CH2CHO (D)

O3 2 2 3CH CH C–CH CH



Alkene & Alkyne

113. CH2 = CH – CH = CH – CH = CH2 2Br (1 eq.)

(60–80°C)X

Major

(A) 2 2BrCH –CH=CH–CH(Br)–CH=CH

(B) 2 2BrCH –CH=CH–CH=CH–CH Br

(C) 2 2CH =CH–CH(Br)–CH(Br)–CH=CH

(D) 2 2BrCH –CH(Br)–CH=CH–CH=CH

114. HCl (1 eq)

(A)Cl

(B) Cl

(C)Cl

(D) Cl

115. C3H7C CH peroxideHBr ‘X’ X is -

(A) C3H7CH = CHBr (B) C3H7CBr = CH2

(C)3 7 |

C H CBr C– BrH

(D) C3H7CH2–CHBr2

116. 2 2Br , H OC

CH

(A)C

O

2 2CH Br (B) CCH

Br

Br

(C) CCHBr

(D)Br C

CH



40

Alkene & Alkyne

117. CH2 = CHCHOHCH = CHMe 2 4H SOMeOH

(A) CH2 = CHCHOHCH2CH(OMe)Me(B) CH2 = CHCH = CHCH(OMe)Me(C) CH2 = CHCH = CHCH2Me(D) CH3 – CH (OMe) CH = CHCH(OMe)Me

118. What is the kinetic product for the following reaction?

3CH+ HCl ?

(A)

Cl3CH

(B)

3CH

Cl(C)

3CH

Cl(D)

3CH

Cl

119. What is the major organic product of the following reaction?

2 4H SO

2Hg +

CH

(A)O

(B) OH

H

H

(C)O

H(D)

HO

H

H

120.What reagents can best be used to accomplish the followingtransformation?

OH

(A) 1. 3BH , THF 2. –2 2HO , H O

(B) 2H , H O

(C) 1. 2 2Hg(OAc) , H O/THF 2. 4NaBH

(D) 1. 2 3 2 3Hg(O CCF ) , CH OH 2. 4NaBH



Alkene & AlkyneMultiple Correct Questions (MCQ) :

121. The alkenes which are more reactive than ethene forelectrophilic addition reaction are

(A) 2CH =CH–Cl (B) 3 2CH –O–CH=CH

(C) 3 2CH –CH=CH (D) 2CH =CH–CHO

122. Which of the following compounds will give same majorproduct on acid catalysed hydration

(A) 2Ph–C–CH=CH3CH

3CH(B) 2Ph–CH–C=CH

3CH

3CH

(C) C=CPh

3CH

3CH

3CH(D) 2C=CH

CH

Ph

3CH3CH

123. The correct products have been reported in reactions.

(A) 2CH =CH–CHO 2 2CH –CH –CHO

Cl

(H Cl(g)(–10°C)

(B) 2CH =CH–COOH 2 2CH –CH –COOHOH

2 2 4H O/H SO

(C) 3 3CH –C=CH–C–CH 3 3CH –CH–CH – C –CH3CH OH3CH

3OCH O

3CH

O2 4H SO

(D) 3 3CH –CH=CH–OCH 3 2 3CH –CH –CH–OCH3CH OH/H+

3OCH



42

Alkene & Alkyne124. Three different alcohols (E), (F) and (G) are synthesised from

the same alkene (P) by using three different reagents (I), (II)and (III) respectively as shown below. Identify the reagents.

(I)

(II)

2CHDCH OH

2CH(OH)CH D

OH

2CH D(F)

(E)

(G)(III)

2CH=CH(P)

(A) (I) is D+/H2O;(II) is 1. Hg(OAc)2, THF–H2O 2. NaBD4

(III) is 1. THF–B2D6; 2. H2O2, OH–

(B) (I) is 1. Hg(OAc)2, THF–H2O 2. NaBD4

(II) is D+/H2O(III) is 1. THF–B2D6; 2. H2O2, OH–

(C) Products (E), (F) and (G) are formed via free radical,carbocation and cyclic carbonium ion intermediate re-spectively.

(D) Products (E), (F) and (G) are formed via mercury-bridgedcarbocation, carbocation and four-centre transition staterespectively.

125. 2H , H O Possible products of the reaction will be

(A)OH

(B)OH

(C)OH

(D)OH



Alkene & Alkyne126. In which of the following reaction(s), major product is formed

by the cyclic intermediate of reactive intermediate?

(A) + HCl

(B) 2 2+ Br –H O

(C) 2H O3 2+ (CF COO) Hg 4NaBH

(D) + HBr

127. Which of the following is correct statement aboutoxymercuration-Demercuration-(A) In the Ist step oxymercuration occurs i.e. water &

Hg(OAc)2 add to double bond(B) In the IInd step demercuration occurs i.e. NaBH4 reduces

–HgOAc group to hydrogen.(C) The net reaction is addition of water according to

Markonikoff rule(D) Rearrangement takes place

128. In which of the following halogen addition reaction, racemicmixture of products is formed?

(A) 3FeCl2 4+ Br –CCl

(B) 3FeCl2 4+ Br –CCl

(C) 3FeCl2 4+ Br –CCl

(D) 3 2 2 4CH –CH=CH + Br –CCl 3FeCl



44

Alkene & Alkyne129. Consider the following addition reaction on a pure

enantiomer of the shown bromoalkene.

+ HBr Products(s)BrH2CH=CH

3CH

What is/are true regarding products of the above reaction?(A) Four stereoisomers of products of the above reaction?(B) A pair of enantiomers and a meso-dibromide are formed(C) Only a pair of diastereomers are formed(D) One of the product is meso-dibromide

130. Identify the correct statement/statements :(A) Alkynes are more reactive than alkenes towards EAR.(B) Alkynes are less reactive than alkenes towards EAR.(C) Alkynes decolourise Br2 water(D) Addition of HBr to alkynes in presence of peroxide

proceeds via Anti-Markownikoff’s rule131. When But-2-yne is brominated, P is formed. When But-2-yne

is reacted with HgSO4 + H2SO4, then Q is formed. Whichstatement is correct form(A) P will be 2,2,3,3-Tetrabromobutane(B) Q will be Butan-2-one(C) In the formation of P, Cyclic intermediate is formed.(D) In the formation of Q, Cyclic intermediate is formed.

132. What are the expected product(s) in the following reaction?

+ NBS hv4CCl

(NBS=N-bromosuccinimide)

(A) Br (B) Br

(C)Br

(D) Br



Alkene & Alkyne133. Predict products(s) in the reaction

+ HBr

(A)

BrH

Kinetically controlled (B)

Kinetically controlledBr

(C) Thermodynamicallycontrolled

Br

(D) Thermodynamicallycontrolled

Br

134. The correct statement(s) regarding following reaction is/are

2 3 2 3CH =CH–CH–CH CH –CH=CH–CH

Br BrI II

2 2CH =CH–CH=CH HBr

(A) At –80°C, I is the major product(B) At room temperature, II is the major product(C) Both of the products I and II are always formed in

comparable amounts(D) Product I isomerises into II on heating above 40°C

135. The correct statement(s) regarding 1,2-butadiene(I) and1,3-butadiene, (II) is/are

2 3CH =C=CH–CH(I)

2 2CH =C–CH=CH(II)

(A) I has perpendicular pi planes while II has parallelpi planes

(B) Both gives the same product on adding 1.0 equivalent atHBr of –80° C

(C) I gives 2,2-dibromobutane while II gives,2,3-dibromobutane, when reacted with excess of HBr atvery low temperature

(D) Both have same length of C=C double bonds



46

Alkene & Alkyne136. Addition of water over alkene occur via

(A) H2O/H+

(B) Hydroboration-oxidation(C) Oxymercuration-demercuration(D) Alkoxymercuration-demercuration

137. Which statement is/are correct for hydroboration oxidation(A) It is the addition of water over alkene(B) It proceeds via formation of 4 membered cyclic TS.(C) It follows Markowniff rule(D) Hydroboration oxidation over propene leads to

propan-1-ol as major product.138. In which case carbocation is not formed as a reaction

intermediate on reaction over alkene.(A) Halogenation (B) Acid hydration(C) Oxymercuration-demercuration(D) Hydroboration-oxidation

139. In which case product is correct.

(A)

Cl

OH

HOCl(B)

NO

Cl

NOCl

(C)

I

Cl

I–Cl(D)

3CH OH

3OCH+H

140. In which case rearrnage product will be major one.

(A) HBr (B)+

2H O/H

(C)+

3CH OH/H (D) 2BrPh



Alkene & Alkyne141. Addition of HCl to 3,3-dimethyl-1-butene yields two prod-

ucts, one of which has a rearranged carbon skeleton. Amongthe following carbocations, select the possible intermediatesin that reaction?

(A)3 3 2(CH ) CCHCH Cl

(B)3 3 3(CH ) CCHCH

(C) 3 2 3 2|(CH ) CC(CH )

Cl

(D)3 2 3 2(CH ) CCH(CH )

142. In the addition of HBr to 1,3-butadiene, one product is calledthe kinetic product and the other is called the thermodynamicproduct. Which of the following descriptors applies to thekinetic product?(A) 1,2 product(B) least stable with less substituted alkene(C) formed fastest at low temperature(D) bromide attack at more substituted site

143. Which of the following alkenes yield(s) 3-bromo-3-methylpentane as the major product upon addition of HBr?

(A) (B)

(C) (D)

144.3 2CH CHCH=CH 3 3CH CH–CHCH

OHA ; Reagent A may not be:

(A) +2H O/H (B) –

3 2 2BH .THF/H O –OH

(C) 2 2 4Hg(OAc) .H O/NaBH (D) 3 2 2BH .THF/H O –AcOH



48

Alkene & Alkyne145. Which series of reactions will not achieve the following trans-

formation?

ClCl

2Br

1

(A) Cl2/CCl4 Br2 (B) HBr Cl2/CCl4(C) Cl2/CCl4 NBS/hv (D) NBS/hv Cl2/CCl4

146. HOOC(P)

2Br4CCl HOOCCH(Br)CH(Br)COOH

(X)

COOH

HOOC COOH(Q)

2Br4CCl HOOCCH(Br)CH(Br)COOH

(Y)

The correct statements with respect to the above pair of reac-tions are that(A) the reactions are stereospecific(B) (X) is meso and (Y) is racemic mixture(C) (X) is racemic mixture and (Y) is meso(D) each of (P) and (Q) gives a mixture of (X) and (Y)

147. 2BrHBr (P)+ MeOH

Cl

OH(Q) product P,Q will be

(A)O Cl

BrP

(B)

O

BrP

(C)O

BrQ

3OCH(D)

O

Q3OCH



Alkene & Alkyne148. Select the reaction(s) that would result in the formation of 2-

bromopropane.

(A) 3 2peroxideCH CH=CH + HBr

(B)3 2

4CClCH CH=CH + HBr

(C) 3 2 3 2hvCH CH CH + Br

(D)3 2 2

4CClCH CH=CH + Br

149. The major product of the reaction given below is :

OH 2Br2H O ?

(A) OHOH

Br (B) OHHOBr

(C)O

2CH –Br

H(D) O 2CH –Br

H

150. Which of the following compounds gives the samecarbocation on ionization?

(A) Br

(B) Br

(C)Br

(D) Br



50

Alkene & AlkyneAssertion / Reason type Questions (A/R) :

(A) If both assertion and Reason is correct explanation of A(B) If both assertion and Reason are correct but Reason is

not correct explanation of A(C) If assertion is correct, reason is wrong(D) If assertion is wrong, reason is correct

151. Assertion: Addition of HCI to 1-isopropenyl–1–methylcyclopentane yields 1–chloro–1,2,2–trimethylcyclohexane.

Reason: Mechanism of reaction is

H + 3CH

3CH3CH

Cl 3CH

3CH3CH

Cl

152. Assertion: and on hydration

give same alcohol.Reason: The intermediate carbocation for both the alkenes

is same.

153. Assertion: The addition of CBrCl3 in the presence of perox-ides takes place faster to 2-ethyl-1-hexene than to1-octene.

Reason: Due to formation of 1° free radical in case of 2ethyl-1-hexene

154. Assertion: The hydroboration oxidation of

D

Dgives

D

OHD

H

Reason: The syn addition of BH3 across the double bondof norbornane takes place mostly from the moreaccesible outside face of the double bond.



Alkene & Alkyne155. Assertion: The addition of chlorine to cyclohexene gives a

racemic mixture of trans-1, 2-dichlorocyclo hex-ane.

Reason: The trans-1, 2-dichlorocyclohexane is less steri-cally crowded than cis-1, 2-dichlorocyclo hexanehence easily formed.

156. Assertion: Acteylene is less reactive than ethylene towordselectrophilic reagents.

Reason: p–electron density in a triple bond is higher thanthat in a double bond.

157. Assertion: The predominant product in the addition of halo-gens to acetylene is the trans isomer.

Reason: The addition of I2 to acetylene gives C=CH

IH

Ias the major product.

158. Assertion: When acetylene is passed into hyochlorus acidsolution dichloroacetaldehyde is formed.

Reason: The process of reaction is

H–C C–H + H–O–Cl H–C=C

ClOH

HHO–Cl

2Cl–C–C–H + H O

Cl

H O

159. Assertion: 2–Bromo–1–butene reacts with HBr to give 2,2–dibromobutane.

Reason: The intermediate carbocation formed is stablishedby +m effect of Bromine atom.

160. Assertion: With the use of BD 3/THF and CH3COOH,2-Butyne gives Cis-2-deutero-2-butene.

Reason: The same product is obtained when the reagentused is BH3/THF and CH3COOD.



52

Alkene & AlkyneMatch the Column type Questions (MTC) :

161. Match the column:

(A) HBrPeroxide (P) Br

(B) HBrNo Peroxide (Q) Br

(C) HClPeroxide (R) Cl

(D)HCl

4CCl (S)Cl

(E) NBS (T)Br

162. Match List-I with List-II and select the correct answer usingthe codes given below the lists:

List-I (Reaction) List-II (Reagents)(A) CH 3–CH=CH2CH3–CHBr–CH3 (P) HBr(B) CH3–CH=CH2CH3–CH2–CH2Br (Q) Br2

(C) CH3–CH=CH2BrCH2–CH=CH2 (R) HBr/Peroxide(D) CH3–CH=CH2CH3–CHBr–CH2Br (S) NBS

163. Match the column:

(A) HBrProxide (P) Electrophilic-addition

reaction

(B) HClProxide (Q) Free-radical-addition

reaction

(C) NBS

3CH

(R) Free-radical-substitutionreaction

(D) 2 3Cl /AlCl (S) Electrophilicsubstitution reaction



Alkene & Alkyne164. Column-I Column-II

(A) 2 4Cl ,CClCl

ClP. Rearrangement

(B) 2Cl ,hv Cl Q. Carbocation

(C) 3CH OHΔ

BrR. Free radical

(D) 2H /H OOH

S. Cyclic intermediate

165. Column-I Column-II

(A)Markownikoffproduct P. 3 2CH –CH=CH HBr

2 2H O ,hv

(B)Anti-Markownikoffproduct Q. 3CHCl +KOH

H3H C 3CH

C=CH

(C) Peroxide effect R. HBr2CH=CH

(D) Mixture ofstereoisomers S. 3 2CF –CH=CH HBr



54

Alkene & AlkyneComprehension type Questions :

Passage : 1In electrophilic addition reaction, alkene behave as anucleophile or base. During reaction electrophile react withalkene in rate determining step to form carbocationaccording to markownikoff rule. In second step carbocationreact with nucleophile to give product so overall additionreaction take place.

166. 4CCl2Br+

Number of product (including stereo) formed in thereaction:(A) 1 (B) 2 (C) 3 (D) 4

167. Correct order of rate of Bromination:

(I) (II) (III)

(A) I > II > III (B) II > I > III(C) III > II > I (D) II > III > I

Passage : 2Homolytic bond fission of a covalent single bond gives rise tofree radicals. Owing to the presence of an odd electron, freeradicals are highly reactive. They have planar to pyramidalgeometry depending upon the groups attached to the C-atomhaving odd electron. Alkyl free radicals are stabilised byhyperconjugation whereas allyl and benzyl free radicals arestabilised by resonance. They are formed as intermediates inthe reaction mixture either in the gaseous phase or in non-polar solvents. Addition of HBr to alkenes in presence of per-oxide, the substitution of allylic or benzylic hydrogen by ‘Cl’at high temperature or by ‘Br’ in presence of NBS are ex-amples of reactions involving free radical intermediates. Nowanswer the following questions :



Alkene & Alkyne168. 3,5-dimethylcyclopentene reacts with N-bromosuccinimide

(NBS) in CCl4 in presence of light or peroxide. Identify theproduct.

3CH3H C+ NBS hv Expected Product

(A) 3CH3H CBr

(B) 3H C

Br

3CH

(C) 3CH3H CBr

3CH3H CBr& (D)

3H C

BrBr

3CH

169. Arrange the following free radicals in the decreasing orderof their stability.

2 2 3 3 2 3CH =CH–CH ; (CH ) C; CH =CH; CH. . . .

(A) 3 3 2 2 2 3(CH ) C > CH =CH–CH > CH =CH > CH. . . .

(B) 3 3 2 2 3 2(CH ) C > CH =CH–CH > CH > CH =CH. . . .

(C) 2 2 3 3 3 2CH =CH–CH > (CH ) C > CH > CH = CH. . . .

(D) 2 2 3 3 2 3CH =CH–CH (CH ) C > CH =CH > CH>. . . .

Passage : 3Addition of HX on alkene proceed through the formation ofcarbocation. This reaction is also known as Markownikoffreaction. According to Markownikoff’s rule addition ofelectrophile occurs on that carbon of alkene which have morenumber of ‘H’ atom.

2Ph–CH=CH HX3 2 2Ph–CH–CH + Ph–CH –CH –X

Major Minor

X



56

Alkene & AlkyneMechanism :

H–X H H – X

3 2 2C–CH + Ph–CH –CH

More stable Less stable

2C=CHH

Ph H

H

Ph

3C–CH + XH

Ph

H

PhC

X

3CH+

PhC

X

3H C HEnantiomer

170. Which of the following alkene can produce diastereomers ?

(A) 3 3CH –CH=CH–CH (B) 3CH=CH–CH

(C) 3CH3CHH

(D) 3 2CH CH=CH

171. Which of the following alkenes will give Markownikoffreaction ?

(A) 3 2HClF C–CH=CH (B) 3 2

HClH C–CH=CH

(C) 2 2HBrO N–CH=CH (D)

3CH2C=CH

3CHHBr

Passage : 4Hydroboration oxidation reaction is a process of addition ofH2O according to Markownikoff’s rule but product resembleAnti-Markownikoff of product.

3 2CH CH=CH 2BH .THF

2 2H O , OH3 2 2CH –CH –CH –OH

Reaction is regioselective, Regioselectivity of reactionin increased by using hindered boranes. THF (Tetrahydrofu-ran) is used to control reactivity of borane.



Alkene & Alkyne

172.3BD .THF

2 2H O ,OHMajor product :

(A)D

3CH

OH3CH

(B)H

D3CH

OH

(C)H

D

3CHOH (D)

H

3CHOHOH

173.H

COOHC=C

HOOC

H3BD .THF

2 2D O ,OH

(A)

COOHDHOD

COOHH (B)

COOHODHD

COOHH (C)

COOHHDOD

COOHH (D)

COOHDHOH

COOHH

Passage : 5To predict relative reactivities of various positions in a givenmolecule two different methods are generally used.

(i). Predictions based on charge distributions:- This approachassumes that the reactivities of a position in a polar reaction isdetermined by the charge density at that position, i.e. anelectrophilic reagent will attack preferentially at the site ofhighest electron density and a nucleophilic reagent will attackpreferentially at the site of lowest electron density. The chargedistribution is ascertained by the examination of theconsequences of inductive and/or resonance effect. Thisapproach is referred to as the isolated molecule method.

(ii). Predictions based on stabilities of intermediates:- This methodassumes that the reactivities of different positions in a givenmolecule are determined only by their relative activation



58

Alkene & Alkyneenergies. Since the activation energy depends on the structuresof the transition state. For the reactions that are belived toinvolve intermediate carbocation, carbanion and free radicals,it is these that are chosen to represent the structure of transitionstates, the stabilities of which are then examined in terms ofinductive effect and/or resonance effect. The assumption isthen made that the more stable the intermediate (i.e. the lowerits energy), the lower is the energy of TS and consequently thelower is the energy of activation leading to that intermediate.This approach is referred to as the localisation energy method.Based on these methods solve question 174–175.

174. In Which molecule attack of electrophile will be easy overalkene.(A) 2 2CH =CH (B) 2CH =CH–Cl

(C) 2 3CH =CH–OCH (D) 2 2CH =CH–NO

175. In which molecule most stable intermediate will be formedafter protonation.

(A) (B) O

(C)O

(D) Cl

Cl



Alkene & AlkyneInteger type Questions :

176. How many of the following reactions, leads to the formationof diastereomers.

(A) 3C=CH–CHH 4CCl

HCl3H C(B)

4CClHBr

(C) 2C=CHH

Ph4CCl

HBr (D)

PhCH

CH

3CHH D

4CClHCl

(E)3CH

2CH 4CClHCl

(F)3CH

4CClHCl

Ph

177. Identify number of chiral centers present in product obtainedby following reaction.

3CH H

2Br4CCl

178. How many different products (excluding stereoisomer) canbe obtained by following reaction.

4HCl, CCl

179. If a pure enantiomer of 5-bromo-2-hexene is treated withBr2–CCl4, how many different tribromides would be formed?

180. If a racemic mixture of 3-methyl-1-pentene is treated withHCl, how many different chloropentane (importantproducts only excluding stereo) would be formed?



60

Alkene & Alkyne

1. What is the product when acetylene reacts with hypochlorousacid ? [AIEEE 2003](A) 3CH COCl (B) 2ClCH CHO

(C) 2Cl CHCHO (D) ClCHCOOH2. Reaction of one molecule of HBr with one molecule of

1,3-butadiene at 40°C gives predominantly. [AIEEE-2005](A) 1-Bromo-2-butene under kinetically controlled conditions(B) 3-Bromobutene under thermodynamically controlled

conditions(C) 1-Bromo-2-butene under thermodynamically controlled

conditions(D) 3-Bromobutene under kinetically controlled conditions

3. Acid catalyzed hydration of alkenes except ethene leads to theformation of [AIEEE-2005](A) Mixture of secondary and tertiary alcohols(B) Mixture of primary and secondary alcohols(C) Secondary or tertiary alcohol(D) Primary alcohol

03Exercise

World of competitions



Alkene & Alkyne4. HBr reacts with CH2=CH–OCH3 under anhydrous conditions

at room temperature to give [AIEEE-2006]

(A) 3 3CH CHO and CH Br

(B) 2 3BrCH CHO and CH OH

(C) 2 2 3BrCH –CH –OCH

(D) 3 3H C–CHBr–OCH

5. Acid catalyzed hydration of alkenes except ethene leads to theformation of [AIEEE-2005](A) Primary alcohol(B) Secondary or tertiary alcohol(C) Mixture of primary and secondary alcohols(D) Mixture of secondary and tertiary alcohols

6. Assertion: Addition of fbromine to trans-2-butene yieldsmeso-2. 3-dibromobutane. [IIT-JEE 2001]

Reason: Bromine addition to an alkene is an electrophilicaddition

(A) Assertion is True, Reason is True, Reason is correctexplanation for Assertion.

(B) Assertion is True, Reason is True, Reason is NOT a correctexplanation for Assertion.

(C) Assertion is True, Reason is False.(D) Assertion is False, Reason is True.

7. 46 5 3 2 4

HgSOH SOC H – C C – CH A [IIT-JEE 2003]

(A)O

(B)O

(C) 6 5 3C H – C=CHCH

OH(D) 6 5 3C H – CH=C–CH

OH



62

Alkene & Alkyne8. On acid catalysed hydration, 2-phenyl propene gives: [JEE 2004]

(A) 2-phenylpropan-2-ol (B) 2-phenylpropan-1-ol(C) 3-phenylpropan-2-ol (D) 1-phenylpropan-1-ol

9. A n organic compound (P), C5H10O reacts with dil. H2SO4 togive (Q) and (R). Both (Q) and (R) give positive iodoform test.The reactivity of organic compound (P) is 1015 times more thanethylene with respect to dil. H2SO4. [IIT-JEE 2004](i) Identify the compounds (P), (Q) and (R)(ii) Give reason for the extraordinary reactivity of compound

10. 3 2CH –CH=CH + NOCl P [IIT-JEE 2006]

Identify the adduct

(A) 3 2CH –CH–CHCl NO

(B)NO Cl

3 2CH –CH–CH

(C)Cl

3 2CH –CH –CHNO

(D)NO

2 2 2CH –CH –CH

Cl

11. The number of stereoisomers obtained by bromination oftrans-2-butene is [IIT-JEE 2007](A) 1 (B) 2 (C) 3 (D) 4

12. The major product of the following reaction is [IIT-JEE 2011]

O2RCH OH

H (anhydrous)

(A) a hemiacetal (B) an acetal(C) an ether (D) an ester

13. In the hydroboration-oxidation reaction of propene withdiborane, H2O2 and NaOH, the organic compound formed is:

[IIT-Mains 2014](A) 3 2CH CH OH (B) 3 3CH CHOHCH

(C) 3 2 2CH CH CH OH (D) 3 3(CH ) COH



Alkene & Alkyne

14. 2 2 2CH –CH =CH on mercuration-demercuration pro-

duces the major product: [IIT-Mains 2014]

(A) 2 3CH –CH–CHOH

(B) 2 2 2CH –CH –CH –OH

(C) 2 2CH –CH–CHOH OH

(D) 2CH –COOH

15. In the following reaction, the major product is

3CH2CH 1 equivalent HBr [IIT-Adv. 2015]

(A)3CH

2H C3CH

Br(B)

3CH

3H C Br

(C)3CH

2H C Br(D)

3CH

3H C Br

Comprehension: In the following reactions [IIT-Adv. 2015]

4Pd-BaSO 2 6i. B H

2 2 2ii. H O , NaOH , H O

2H O

+ii. H , heat2i. EtMgBr, H O

4 2 4HgSO , H SO

8 6C H2H 8 8C H X

8 8C H O Y

16. Compound X is:

(A) 3CHO

(B)OH

3CH

(C)OH

(D) CHO



64

Alkene & Alkyne17. The major compound Y is:

(A) 3CH (B) 3CH

(C) 3CH2CH

(D)3CH

3CH

18. Anti-Markownikoff addition of HBr is not observed in :[CET (J & K) 2012]

(A) 2-butene (B) 1-butene (C) propene (D) 2-pentene19. The negative part of the addendum adds on to unsaturated

carbon atom joined to the least number of hydrogen atoms.This statement is called: [AFMC 2004](A) Saytzelff rule (B) Kharasch effect(C) Markownikoff’s rule (D) Anti-Saytzeff rule

20. When propyne is treated with aqueous H2SO4 in presence ofHgSO4, the major product is: [PMT (Kerala) 2010](A) propanone (B) 2-propanol(C) ethanal (D) ethyne

21. Reaction of HBr with propene in the presence of peroxide gives:[AIPMT 2004]

(A) isopropyl bromide (B) allyl bromide(C) n-propyl bromide (D) 3-bromopropane

22. Which of the following reactions will yield 2,2-dibromopropane? [CPMT 2004](A) H2C = CHBr + HBr (B) CH3C = CCH3 + 2HBr(C) CH3C = CH + 2HBr (D) CH3CH = CHBr + HBr

23. Which of the following alkenes will give an optically activealcohol when treated with H2O/H2SO4? [CPMT 2004](A) 1-Butene (B) Ethene(C) Propene (D) 2-Methyl propene



Alkene & Alkyne24. Acid catalysed hydration of alkenes except ethene leads to the

formation of: [JCECE (Med.) 2008](A) primary alcohol(B) secondary of tertiary alcohol(C) mixture of primary and secondary alcohols(D) mixture of secondary and tertiary alcohols

25. The only alcohol that can be prepared by the indirect hydrationof alkene is: [AFMC 2005](A) ethyl alcohol (B) propyl alcohol(C) isobutyl alcohol (D) methyl alcohol

26. 3-phenyl propene on reaction with HBr gives (as a majorproduct): [AIIMS 2005]

(A) 6 5 2 3C H CH CH(Br)CH (B) 6 5 2 3C H CHCH(Br)CH CH

(C) 6 5 2 2 2C H CH CH CH Br (D) 6 5 2C H CH(Br)CH = CH

27. Trans-2-butene-Br2 gives: [CET (Gujarat) 2006]

(A) BrHBrH

3CH

3CH

(B) BrH

3CHBr H

3CH

(C) BrH

3CHBr

H3CH

(D) BrH3CH

Br H3CH

28. Reaction of acetylene and propylene with HgSO4 in presenceof HgSO4 produces respectively: [BHU (Med.) 2006](A) acetone and acetaldehyde(B) acetaldehyde and acetone(C) propanaldehyde and acetone(D) acetone and propanaldehyde



66

Alkene & Alkyne29. Predict the product ‘C’ obtained in the following reaction of 1-

butyne:

3 2HICH CH C CH + HCl (B) (C) [AIPMT 2007]

(A) 3 2 2CH CH – CH – CH ClI

(B) 3 2 3CH CH – C – CHI

Cl

(C) 3 2 2CH – CH – CH CH ICl

(D) 2 2 2CH CH CH – C – HI

Cl30. 3 2CH – CH – CH = CH + HBr

3CH'A' ,

‘A’ (predominantly) is: [AIPMT 2008]

(A) 3 3CH – CH – CH – CH

3CHBr(B)

3 3CH – CH – CH – CH3CH Br

(C) 3 2 2CH – CH – CH – CH Br

3CH(D) 3 2 3CH – C – CH CH

3CH

Br

31. The order of reactivity of the alkenes,

3 2 2 3 2 2 2(CH ) C = CH , CH CH = CH , H C = CHI II III

when subjected to acid catalyzed hydration is:[AMU (Med.) 2009, 10]

(A) I > II > III (B) I > III > II (C) III > II > I (D) II > I > III32. Identify the product in the reaction

+ 2 +3H O , Hg ?Ph–C C–Me [DUMET 2010]

(A) 2 2PhCH CH CHO (B) 2 3PhCOCH CH

(C) 2 3PhCH COCH (D) PhCOCOMe



Alkene & Alkyne33. Reaction of HBr with propene in absence of peroxide is a/an:

[PMT (Kerala) 2011](A) electrophilic addition (B) electrophilic substitution(C) nucleophilic addition (D) nucleophilic substitution

34. In the following reaction

2 5C H3 2CH – C – CH = CH

3CH+

2H O / H (A) + (B)major

productminor

product

The major product is : [AIPMT (Prelims) 2012]

(A) 3 3H C – C – CH – CH3CH

OH3CH(B) 3 3H C – C – CH – CH

3CH

OH 3CH

(C) 2 2 3CH – C – CH CH3CH

OH 3CH(D) 3 2 2H C – C – CH – CH

3CH

OH3CH

35. In the reaction with HCl, an alkene reacts in accordancewith the Markovnikov’s rule, to give a product 1-chloro-1-methylcyclohexane. The possible alkene is : [AIPMT 2015]

(A)2CH

(A) (B)3CH

(B)

(C) (A) and (B) (D)3CH



68

Alkene & Alkyne

AnswersSubjective Approach

011. Organic reactions are generally of 4 types.

(A) Substitution reaction– Here old sigma bonds are broken& new bond is formed.

A – B C A – C B

(B) Addition reaction– Here generally bonds are broken &corresponding bonds are formed.

A = B + C – D A – Bπ

C Dσσ

(C) Elimination reaction– Here generally old bonds arebroken & corresponding a new bonds are formed.

A = B + C – DA – B π

C Dσσ

(D) Rearrangement reaction– Here generally there is changein connectivity of atom.

A – B – C A – C – B

2. Reagents are the attacking species which attacks over thesubstrate. They may be e– rich, e– deficient or odd e– species.



Alkene & Alkyne3. Electrophiles are e– deficient attacking species. They have e–

deficiency in the form of either(A) Positive charge (B) Incomplete octet or(D) Vacant orbitalThose factors which withdraws e– density from electrophileincreases its electrophilicity.

4. Nucleophiles are e– rich attacking species which attacks arenon-metal. They have complete octet with either presence oflone pair or –ve charge. Those factors which donates e– densitytowards nucleophilic centre generally increases itsnucleophilicity.

5. Free radicals are odd e– reactive species which attacks overanother free radicals or neutral molecules. Free radicals aregenerally formed by either presence of light, peroxide or hightemperature.

6. Leaving groups are those atoms or groups which goes out fromsubstrate from any chemical reaction. Those factors whichstabilizes leaving group increases its leaving group tendency.

7. – – – –3 3OH > Ph–O > CH –C–O > CH –S–O

O

O

O

– – – –I > Br > Cl > F

3 2NH H O

8.– – – –

3 3CH –S–O > CH –C–O > Ph–O > H–O

O

O

O

– – – –I > Br > Cl > F

2 3H O NH

9. Solvents are the medium in which chemical reaction has totake place. They are of 2 types(A) Polar (B) Non polar



70

Alkene & AlkynePolar solvents are those which have polarity in the moleculesuch as H2O, CH3OH etc. Non polar solvent are those whichdo not have any polarity in molecule such as benzene,cyclohexane.Polar solvent are further of 2 types(A) Polar protic– where H+ can be removed from solvent such

as H2O, NH3, CH3COOH(B) Polar aprotic– where solvent do not easily loose H+ but

have polarity such as CH3COCH3, CH3SCH3 etc.10. Base are those e– rich species which attacks over H+.

Nucleophile are those e– rich species which attacks over non-mainly C. Ligand are those e– rich species which attacks overmetal.

11. General chemical reaction of alkene & alkynes are electrophilicaddition reaction.

3 2 3 2CH – CH = CH CH – CH – CHE–NuE

Nu12. When unsymmetrical alkene or alkyne reacts with

unsymmetrical reagent in electrophilic addition reaction, thenpositive part of reagent attached to that carbon which havemore number of hydrogen while negative part of reagentattached to that carbon which have less number of hydrogen.This rule is called as Markownikoff rule.

3 2 3 2CH – CH = CH CH – CH – CHE–NuE

Nu13. Basic concept behind Markownikoff rule is the stability of

carbocation.3 2 3 2 2

HClCCl – CH = CH CCl – CH – CH – Cl (Violation of Markownikoff rule)

3 2 3 3

|HClCl

CH – CH = CH CH – CH– CH(Follow Markownikoff rule)



Alkene & Alkyne14. (A) Bromine water test (B) Baeyer’s reagent.

15. Dilute alkaline 4KMnO is commonly called as Baeyer’s reagent.It is used to distinguish saturation & unsaturation ofcarbon-carbon bond.

16. Addition of water to alkene is hydration reaction. Hydrationof alkene takes place in acedic medium & reaction &mechanism follow as below. Reaction:

3 2 3 32

|+H O/HOH

CH - CH = CH CH – CH- CH

Mechanism:

3 2 3 3 3 3CH – CH = CH CH – CH – CH CH – CH – CH2H O

..+H+H

OH

17. (A) Hydration in acidic medium using +2H O /H .

(B) Hydroboration-oxidation using 2 6B H followed by–

2 2H O /OH .

(C) Oximercuration-demercuration using 2 2 2(Ac O) Hg / H O

followed by 4NaBH .

18. Oximercuration-demercuration is addition of water to alkeneusing 2 2 2(Ac O) Hg / H O followed by 4NaBH .

4

|

3 2 3 322i) Hg (OAC) /H O

ii) NaBH

OHCH –CH = CH CH – CH– CH

19. Alkoxymercuration-demercuration is addition of alcoholusing 2 2(Ac O) Hg / ROH followed by 4NaBH .

4

|

3 2 3 32i)(AC O)Hg/ROH

ii) NaBH

ORCH – CH = CH CH – CH– CH



72

Alkene & Alkyne20. Hydroboration-oxidation is addition of water using 2 6B H

followed by –2 2H O /OH .

63 2 3 2 2

2

2 2

i)B H-ii) H O /OHCH –CH = CH CH – CH – CH – OH

21. Hydroboration-oxidation is simply addition of water butmachanism follow via 4 membered cyclic TS.

3 2 3 2 232 6

2 2

i) B H or BH–ii) H O /OH

CH – CH = CH CH – CH – CH – OH

Mechanism:

2BH

3 2 3 2 3 2 2 2CH –CH= CH CH – CH CH CH – CH –CH –BH

H2H – BH 3 2 2 3(CH –CH –CH ) B

3 2 2 3 3 2 22 2 –H O /OH(CH – CH –CH ) B 3 CH – CH – CH –OH

As here hydrogen attached as hydride so reaction followsMarkownikoff rule but product resemble’s Anti Markownikoffproduct.

22. Bromination of alkene is simply the addition of bromine toalkene to form dibromoalkane as product.Reaction:

3 2 3 22

|

|

BrBr

CH –CH = CH CH – CH– CH

Br

Mechanism:

3 2 3 2 3 2CH –CH= CH CH –CH CH CH – CH–CHBr

Br

Br

BrBr

Br

(Cyclic bromonium ion)



Alkene & Alkyne23.

+

+

+

3 2CH –CH=CH3 2CH –CH–CH

OH

Br

3 2CH –CH–CH

Br

Br

3 2CH –CH–CH

Br

Br

3 2CH –CH–CH

Br

Br

3 2CH –CH–CH

Br

Br

3 2CH – CH – CH

Cl

Br

3 2CH –CH–CH

Br

3OCH

2 4Br /CCl

2 2Br /H O

2Br /NaCl

2 3Br /CH OH

24. Reaction:

3 2 3 3

|HBrBr

CH –CH = CH CH – CH– CH

Mechanism:

3 2 3 3 3 3CH – CH = CH CH – CH – CH CH – CH – CHBr

BrH

25. Reaction:

3 2 3 2

|

|

HO–ClOH

CH – CH = CH CH – CH– CH

Cl

Mechanism:

3 3 2 3 2CH –CH=CH CH – CH CH CH –CH–CH

OH

ClCl..

OHCl

HO



74

Alkene & Alkyne26. Reaction:

3 2 3 2

|

|

I–ClCl

CH – CH = CH CH – CH– CH

I

Mechanism:

3 2 3 2 3 2CH –CH=CH CH –CH CH CH – CH–CH

I

Cl Cl

II..

Cl27.

+2H O/H

ICl

81

2

345

6

7

Br

OHBr

BrOH

ICl

ClOH

Cl

OH

OH

HOClHCl

i 3) BH–

2 2ii) H O /OH2 4Br /CCl

2 2Br / H O

4ii) NaBH2 2ii) (Ac O)Hg/H O

28. When unsymmetrical alkene is treated with HBr in presence ofperoxide then hydrogen will attached to that carbon whichhave less number of hydrogen while bromine is attached tothat carbon which have more number of hydrogen. Thisconcept is against Markownikoff rule so it is called asAnti-Markownikoff rule. This abnormality was first reportedby kharasch so it is called as Kharasch effect.

3 2 3 2 22 2HBr/(Ph C )O O

CH –CH=CH CH –CH –CH –Br



Alkene & Alkyne29. NBS is N-Bromo Succinimide. NBS is used to replace benzylic

or allylic H with Br via free radical mechanism.

3 2 2 2

|NBSBr

CH –CH = CH CH – CH = CH

30. NCS is N-Chloro Succinimide. NCS is used to replace benzylicor allylic H with Cl via free radical mechanism.

3 2 2 2

|NCSCl

CH – CH = CH CH – CH = CH

31.2 2 2 2

2|Cl

High T

ClCH – CH = CH CH – CH = CH

32. (A)Br

(B)Br

(C) Br (D)Br

33. Reaction:

3 3 3

|

|HCl

Cl

CH – C CH CH – C – CHCl

Mechanism:

3 3 2 3 2

3 33 3

CH –C CH CH –C=CH CH – C= CH

CH – C–CHCH –C–CH

HCl Cl H

ClCl

Cl

Cl

Cl

34. Reaction:

3 3 2CH – C CH CH – C – CHClHOClO



76

Alkene & AlkyneMechanism:.

Cl

OH

Cl

HO

.. Cl

OH

Cl

OH

OH

Cl..

OHOH

OH3 2CH –C–CHCl 2–H O

O

3 3 3CH –C CH CH –C=CH CH –C = CH

3CH –C CH–Cl3 2CH –C–CHCl

35.3CH – C CH 2 6i) B H

–2 2ii) H O /OH 3 2CH – CH – C – H

O

36. General hydration of alkyne occur in presence of 4HgSO of

along with dil 2 4H SO .

3CH –C CH+

2 4H O/HgSO /H3 3– –CH C CH

O

Mechanism:

OO–H–H+

Hg

2H O..Hg2+

3 3 3 2 3 3CH –C CH CH –C=CH CH –C=CH CH –C –CH

37. Mercury sulphate reacts with alkyne and form anintermediate over which water attacks to form product.

3 3 3 2 3 3CH –C CH CH –C=CH CH –C=CH CH –C–CHOO–H

Hg

2H O..

Intermediate

4HgSO



Alkene & Alkyne

38. HClCl

39. HClCl

40. Intermediates formed from alkene is generally more stable thanintermediate formed from alkyne. So alkenes are more reactivethan alkynes.

23CH –CH=CH 3 2CH –CH–CHE+

E(more stable)

3CH –C CH 3CH –C=CHE+

E(less stable)

41. As alkene, Alkynes & water are electron rich so H+ is added tocreate electron deficient centre in alkene or alkyne over whichwater will attack.

3 3CH –CH–CHH+

3 2CH –CH CH

3CH –C CH 3 2CH –C=CHH+

42. X

3

3 2 2

|CH

CH – CH – CH – CH – OH Y

3

3 2

|CH O

CH – CH – CH – C– H

43. X

3

3 3

| |CH OH

CH – CH – CH– CH

Y

3

3 3

|CH

CH – CH – C– CH

O



78

Alkene & Alkyne

44.

Br

BrBr

Br

M

Br

BrBr

Br Br

BrO

+

N

Br

Br

Br Br

Br+Br3OCH

3OCH

O

Br

Br

Br Br

Br+BrCl

ClP

45.

2 6i) B H–

2 2ii) H O /OH2 6i) B H

3ii) CH COOH

2Br

ICl

I

HCl

HOCl + 2+2H O/H /Hg

ii) NaB

H 4

i) (Ac O)H

g/HO

O

2

21 2

3

45

6

7

8

Cl

Cl

I

Cl

Cl

BrBr

Br

Br

O

H

O

O

O

Cl

Cl



Alkene & Alkyne46. Terminal alkyne have acidic hydrogen so give white ppt with

Tollen’s reagent & red ppt with 2 2 4Cu Cl /NH OH butnon-terminal alkyne do not give such reactions.

2 2 4Cu Cl / NH OH

Tollen's reagentR–C CH R–C C Ag

R–C C Cu

white ppt

Red ppt

2 2 4Cu Cl /NH OH

Tollen's reagentR–C C–R No ppt

No ppt

47.

48. Rate of electrophilic addition reaction depends on the stabilityof carbocation formed after protonation while stability ofsubstrate depends on electronic delocalization of bond.

49. Rate of electrophilic addition reaction depends on stability ofcarbocation. Carbocation formed by 1,3-Butadiene is morestable than carbocation formed by But-1-ene so is the order.

50. HBr

Br

+

Br

+ + BrBr

51. HBrBr

+Br

+ Br

52. (A)

N

Br (B) O

Br

(C) O

Br

O (D) Br

N

53. (A)3 3CH –C–CH

O(B) O



80

Alkene & Alkyne

(C) OHH

OO (D) OH + H–C

O

54. Ph–CH–C CH Ph–CH=C=CH

OH+H Ph–CH–C CH

..+–H

2H O..

Ph–CH=C=CHPh–CH=CH–C–H

O–HO

55. (A)HO

(B) O

(C)O

(D) PhPh

OH



Alkene & Alkyne

AnswersObjective Approach

0201. (B) 02. (B) 03. (B) 04. (A) 05. (A)06. (B) 07. (A) 08. (C) 09. (A) 10. (B)11. (B) 12. (C) 13. (A) 14. (D) 15. (B)16. (B) 17. (B) 18. (D) 19. (D) 20. (B)21. (D) 22. (B) 23. (B) 24. (C) 25. (B)26. (C) 27. (C) 28. (B) 29. (D) 30. (C)31. (D) 32. (B) 33. (B) 34. (D) 35. (C)36. (B) 37. (D) 38. (A) 39. (A) 40. (D)41. (A) 42. (B) 43. (C) 44. (A) 45. (C)46. (B) 47. (B) 48. (C) 49. (B) 50. (A)51. (B) 52. (D) 53. (A) 54. (B) 55. (B)56. (B) 57. (D) 58. (B) 59. (B) 60. (B)61. (A) 62. (B) 63. (A) 64. (A) 65. (C)66. (D) 67. (A) 68. (B) 69. (A) 70. (A)71. (C) 72. (A) 73. (A) 74. (D) 75. (A)76. (B) 77. (A) 78. (D) 79. (A) 80. (D)81. (C) 82. (C) 83. (D) 84. (B) 85. (A)86. (A) 87. (B) 88. (C) 89. (C) 90. (C)



82

Alkene & Alkyne91. (C) 92. (C) 93. (C) 94. (A) 95. (C)96. (B) 97. (B) 98. (D) 99. (C) 100. (B)101. (C) 102. (A) 103. (A) 104. (B) 105. (C)106. (C) 107. (C) 108. (B) 109. (B) 110. (C)111. (A) 112. (C) 113. (B) 114. (D) 115. (D)116. (A) 117. (B) 118. (D) 119. (A) 120. (A)121. (B,C) 122. (A,B,C,D) 123. (A,B,D) 124.(B,D)125. (A,C,D) 126. (B,C) 127. (A,B,C) 128.(A,C,D)129. (C,D) 130. (B,C,D) 131. (A,B,C,D) 132.(A,B,C)133. (B,C) 134. (A,B,C) 135. (A,B) 136.(A,B,C)137. (A,B,C,D) 138. (A,C,D) 139. (A,B,C,D) 140.(A,C)141. (B,D) 142. (A,B,C,D) 143. (A,B,C,D) 144.(A,B,D)145. (A,B,C) 146. (A,B) 147. (A,C) 148.(B,C)149. (C,D) 150. (A,B)151. (A) 152. (A) 153. (C) 154. (A) 155. (B)156. (B) 157. (C) 158. (A) 159. (A) 160. (B)161. (A–P, B–Q, C–S, D–T) 162. (A–P, B–R, C–S, D–Q)163. (A–Q, B–P, C–R, D–S) 164. (A–S, B–R, C–P,Q, D–P,Q)165. (A–R, B–P,Q, C–P, D–Q,R,S)166. (B) 167. (A) 168. (A) 169. (C) 170. (C)171. (D) 172. (B) 173. (C) 174. (C) 175. (B)176. (4) 177. (3) 178. (1) 179. (4) 180. (2)



Alkene & Alkyne

AnswersWorld of Competitions

0301. (C) 02. (C) 03. (C) 04. (D) 05. (D)

06. (B) 07. (A) 08. (A) 09. O

P

O

HQ

OH

R10. (A) 11. (A) 12. (B) 13. (C) 14. (A)15. (D) 16. (C) 17. (D) 18. (A) 19. (C)20. (A) 21. (C) 22. (C) 23. (A) 24. (B)25. (A) 26. (B) 27. (A) 28. (B) 29. (B)30. (D) 31. (C) 32. (B) 33. (A) 34. (B)35. (C)


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