chemistry , organic chemistry , the master of chemistry . its a compiled of many well written books ....
Mechanism of
Organic Reactions For world of competitions
By
AJNISH GUPTA & BHARTI GUPTA Professor of Organic Chemistry
(i)
Copyright © 2015 by Ajnish Gupta All rights reserved. No part of this publication may be reproduced, stored in a database or retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written Permission of the writter.
First Indian Reprint, 2015 This edition is ma nufa ctured in India n a nd is authorized for sale only in India, Bangladesh, Pakistan, Nepal, Sri Lanka & Maldeves. Printed & Distributed by: Udaan Classes Pvt. Ltd. Rainbow building, Patna & Madhur Satyapushpa Shubhash Nagar, Kota 9122057123 Price: Rs. 499/-
(ii)
Preface The guiding principle in writing this book was to create a textbook for students- a textbook that presents the ma terial in a way tha t they le arn to solve all the questions along with the strategy to approach the problems. In this book we mixed all our teaching experience of 11 yea rs a long with theora tica l a nd experimenta l knowledge to generate a hand book for all students to reason their way to a solution rather than memorize a multitude of facts, hoping they don’t run out of memory. This book covers mainly 6 units along with 10 test papers to judge your knowledge which help you to solve chemical reactions of organic chemistry and remove the fever of mechanism of organic reactions. Organic chemistry is very easy and conceptual subject and need proper understa nding of the basics a nd stretegy to solve the questions in corret manner. This book a lso covers a ll the questions of AIEEE, IIT-Mains, IIT-Advanced, AIPMT & other medical exams from 2000 to 2015. In this book balance has to be achieved between the number of questions and the quality of the questions, especially because it is relatively easy to frame a very large number of multiple-choice questions and theory of the subject. We would like to thank the editors and production staff for their efforts in bringing out the book. Suggestions from readers for the improvement of the book are welcome. Ajnish Kumar Gupta & Bharti Gupta
[email protected] 9122057123
(iii)
Acknowledgement We are tha nkful to all the teachers who taught us during the concept building session of our life specially Dr. Nizamuddin sir, senior Chandra Vijay Rao and Dr. Vijay Pratima Mittal madam. We have written this book to remove the fever of organic chemistry from mind of students. We particularly want to thank many wonderful and talented students whom we have taught over the years who in turn taught us how to be a good teacher and how we can help others. We want to make this book as user friendly as possible, and we will appreciate any comments that will help us to achieve this goal in future editions. Finally, this edition has been presented before you with efforts to make it error free. Any that remain are our responsibility; if you find any, please let us know so they can be corrected in future printing. Ajnish Gupta & Bharti Gupta Professors of Organic Chemistry
[email protected] 09122057123
(iv)
Table of Contents Page No. 01
Unit 1 : Alkene and Alkynes Exercise 01 : Subjective approach
02
Answer
68
: Subjective approach
Exercise 02 : Objective approach
08
Single correct questions (SCQ)
08
Multiple correct questions (MCQ)
41
Assertion/reason type questions (A/R) 50
Answer
Match the column type ques. (MTC)
52
Comprehension type questions
54
Integer type questions
59
: Objective approach
81
Exercise 03 : World of competition
60
Answer
83
: World of competition
Unit 2 : Oxidation, Reduction & Alkane
84
Exercise 01 : Subjective approach
85
Answer
143
: Subjective approach
Exercise 02 : Objective approach
92
Single correct questions (SCQ)
92
Multiple correct questions (MCQ)
112
Assertion/reason type questions (A/R) 118
Answer
Match the column type ques. (MTC)
120
Comprehension type questions
123
Integer type questions
126
: Objective approach
(v)
154
Exercise 03 : World of competition
129
Answer
156
: World of competition
157
Unit 3 : Aromatic compounds Exercise 01 : Subjective approach
158
Answer
242
: Subjective approach
Exercise 02 : Objective approach
172
Single correct questions (SCQ)
172
Multiple correct questions (MCQ)
194
Assertion/reason type questions (A/R) 199
Answer
Match the column type ques. (MTC)
202
Comprehension type questions
204
Integer type questions
207
: Objective approach
268
Exercise 03 : World of competition
210
Answer
: World of competition
270
Test-1
: Hydrocarbon & Benzene derivatives
272
Answer
: Test-1
282
Unit 4 : Alkyl halide, alcohol & ether
283
Exercise 01 : Subjective approach
284
Answer
385
: Subjective approach
Exercise 02 : Objective approach
290
Single correct questions (SCQ)
290
Multiple correct questions (MCQ)
341
Assertion/reason type questions (A/R) 348
Answer
Match the column type ques. (MTC)
350
Comprehension type questions
352
Integer type questions
356
: Objective approach
(vi)
397
Exercise 03 : World of competition
360
Answer
: World of competition
400
Test-2
: Alkyl halide, alcohol & ether
402
Answer
: Test-2
413
Unit 5 : Aldehyde, Ketone, Carboxylic acid 414
and Derivatives Exercise 01 : Subjective approach
415
Answer
484
: Subjective approach
Exercise 02 : Objective approach
424
Single correct questions (SCQ)
424
Multiple correct questions (MCQ)
442
Assertion/reason type questions (A/R) 446
Answer
Match the column type ques. (MTC)
449
Comprehension type questions
452
Integer type questions
458
: Objective approach
507
Exercise 03 : World of competition
461
Answer
: World of competition
509
Test-3
: Aldehyde, Ketone, Carboxylic acid and Derivatives
Answer
: Test-3
510 521
Unit 6 : Biomolecules, Polymer, POC and 522
Physical properties Exercise 01 : Subjective approach
523
Answer
578
: Subjective approach
Exercise 02 : Objective approach
525
Single correct questions (SCQ)
525
Multiple correct questions (MCQ)
540
(vii)
Assertion/reason type questions (A/R) 545
Answer
Match the column type ques. (MTC)
547
Comprehension type questions
549
Integer type questions
551
: Objective approach
588
Exercise 03 : World of competition
554
Answer
: World of competition
590
Test-4
: Biomolecules
592
Test-5
: Reduction, Oxidation, Hydrocarbon, & Derivative, Alkyl halide alcohol & Ether 603
Test-6
: Reduction, Oxidation, Hydrocarbon & Derivative, Alkyl halide alcohol & Ether 613
Test-7
: Aldehyde, Ketone, Carboxylic acid and Derivatives
624
Test-8
: Mixing of chapters in organic reactions 635
Answer
: Test-4, 5, 6, 7, 8
645
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Alkene & Alkyne
Unit
1
Alkene and Alkynes
Objective This unit give you a n understa nding of “ Genera l Orga nic chemistry of alkene & Alkyne” and covers following topics: Reaction of HX Reaction of H2 O/H+ Reaction of ROH/H+ Reaction of X2 Reaction of X-X’ Reaction of NOX Reaction of HOX Oximercuration-Demercuration Alkoxymercuration-Demercuration Hydroboration-Oxidation
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1
Alkene & Alkyne
Exercise
01 Subjective Approach You can’t learn organic chemistry because there’s too much of it. You can learn trivial things like name of compounds but that doesn’t help you to understand the principle behind the subject. You have to understand the principle because the only way to tackle organic chemistry is to learn to work it out. That is why we are first providing you some questions so that your understanding about the topic should be increased. These problems should be set you on your way but they are not the end of the journey as you begin your journey to understand organic chemistry. The problem would be of little use to you when you could not check your answers. For the maximum benefit, you need to solve all the problems without looking the answers. Then you should compare your answers or suggestions with ours before going to next chapter. If any answer is mismatch then darken those question numbers with red pen and again have a micorscopic look over it and its theory and correct it before proceeding further. Here starts the first set of 55 questions 1. What are the general types of organic reactions. Comment over it by taking simple alphabets without any reaction. 2. Wha t is rea gent. Na me the types of reagent generally we encounter in organic chemistry.
2
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Alkene & Alkyne 3. What is a n electrophile a nd what a re the fa ctors which increases the electrophilic nature of any molecule. 4. What is nucleophile and what a re the factors which Increases the nucleophilic character of any molecule. 5. What is free radical and what a re the factors which increases the free radical formation easy in a ny molecule. 6. What is leaving group and what are the factors which increases the leaving group character of a ny species. 7. Write the order of nucleophilic character in given molecule. O O OH – , Ph–O – , CH 3 –C–O – , CH 3 –S–O – I – , Br– , Cl – , F –
O NH 3 , H 2 O
8. Write in decreasing order of leaving group character in given molecules. O O OH – , Ph–O – , CH 3 –C–O – , CH 3 –S–O – –
–
–
I , Br , Cl , F
–
O NH 3 , H 2 O
9. What are solvents. How they are classified. Write example of each types. 10. What is the basic difference between base, nucleophile and ligand. 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 importa nt in organic chemistry. 16. Wha t is genera l hydra tion rea ction of alkene. Give the mechanism of hydration of propene.
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3
Alkene & Alkyne 17. 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) Br2 / CCl 4
(B) Br2 /H 2 O
(C) Br2 / NaCl
(D) Br2 / CH 3OH
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. 8
7 ICl
6
HOCl
Br2 /CCl 4
HCl H2 O/H+
Br2 /H2 O
5
1
2
ii) (Ac2O)Hg/H2 O ii) NaBH4 i) BH3 ii) H2 O 2 /OH–
3
4
4
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Alkene & Alkyne 28. 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 hea ted 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 on alkyne. 34. Write the reaction as well as mechanism of addition of HOCl on propyne. 35. What will be obtained as a product when propyne undergoes hydroboration-oxidation reaction. 36. How general hydration of alkyne occur. Give reaction as well as mechanism of it taking propyne as substrate. 37. What is the role of mercury sulphate in hydration reaction of alkyne along with dilute sulphuric acid. 38. What will be the major product obtained when compound ha ving conjuga tion of a lkene & a lkyne such a s pent-1-en-3-yne is treated with 1 eq. of HCl. 39. What will be the major product obtained when compound having double bond & triple bond are not is conjugation such as pent-1-en-4-yne is treated with 1 eq. of HCl. 40. Why alkenes are generally more reactive than alkyne towards any electrophilic addition reaction. 41. Why some acids are added to the reaction chamber before adding water in the hydration reaction of alkene & alkynes.
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5
Alkene & Alkyne 42. What is the major product of hydroboration oxidation reaction of following compounds. CH3 |
i) B2H6 (A) CH3 – CH – CH = CH 2 X ii) H2O 2 /OH– CH3 |
i) B H
2 6 Y (B) CH3 – CH – C CH ii) H O /OH– 2
2
43. What is the major product of oximercuration-demercuration of following compounds. CH3 |
i)(Ac 2O)Hg/H2O (A) CH3 – CH – CH = CH2 X ii)NaBH4
CH3 |
i)(Ac 2O)Hg/H2O (B) CH 3 – CH – C CH Y ii)NaBH 4
44. Write the product of bromination in different condition. Br2 /CCl 4 Br2 /H 2 O Br2 /CH3 OH
M N O
Br2 /NaCl
P 45. Write the major product of following reaction.
HCl
i) B 2H 6
i) B2 H 6 ii) CH 3COOH
6
H
O C
l
7
O 2 H2 g/ ) H BH 4 Br2 O a 2 c A i i) N )i (
1
8
ii) H 2O 2 /OH ICl
5
–
3
H 2O/H +/Hg 2+
4
46. How terminal alkyne is distinguish from non-terminal alkynes.
6
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Alkene & Alkyne 47. 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 that of But-1-ene. 50. Write the structures of total isomers (including stereo) formed when one quivalent of HBr is added to Buta-1,3-diene. 51. Write the structures of total isomers (excluding stereo) formed when one equivalent of HBr is added to Hexa-1,3,5-triene. 52. What will be the product of bromination of following substrate. H
OH
OH
(D) N H 53. What will be the major product of acid hydration in given compounds. N
(A)
(B)
(C)
(A) H 2 C = C = CH2
(B)
(C)
(D)
O
O
O
54. Write the mechanism of following interconversion. OH Ph – CH – C CH
H 2O /H +
O Ph – CH = CH – C – H
55. Write the ma jor product of protona tion in following compounds. O O (A)
(B)
OH
(C)
HO
(D) Ph
Ph
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7
Alkene & Alkyne
Exercise
02 Objective Approach Single Correct Questions (SCQ) : 1.
CH2 =CH2 I
CH3 –O–CH=CH 2 II
Cl–CH=CH 2 IV
OHC–CH=CH 2 V
CH 3 –CH=CH 2 III
Correct order for electrophilic addition reaction of given compound follows (A) I > II > III > IV > V (C) II > IV > III > I > V
(B) II > III > I > IV > V (D) V > IV > II > III > I
O
Cl
O
CH 3
2. I
II
III
IV
V Correct order for electrophilic addition reaction of given compound 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
8
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Alkene & Alkyne Ph
3.
Ph
Ph–CH=CH–Ph II
I
Ph–CH=CH–CH 3 III
CH3 –CH=CH–CH 3 IV
Correct order for electrophilic addition reaction of given compound follows (A) I > II > III > IV
(B) I > III > II > IV
(C) I > II > IV > III
(D) II > I > III > IV
4. H 2 C=CH 2 CH 3 –CH=CH 2 CH 3 –C=CH2 | I II CH3 II
CH 3 –C = C–CH 3 |
|
CH3 CH3 IV
Correct order for electrophilic addition reaction of given compound follows
5.
(A) IV > III > II > I
(B) I > II > III > IV
(C) III > IV > II > I
(D) IV > II > I > III Cl
CH=CH2
CH 3 I
CH=CH 2 II
CH 3 O
O2N
CH=CH 2 III
CH=CH2 IV
Correct order for electrophilic addition reaction of given compound follows
6.
(A) III > I > II > IV
(B) IV > II > I > III
(C) III > II > I > IV
(D) IV > III > II > I
IV
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9
Alkene & Alkyne Correct order for electrophilic addition reaction of given compound 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 addition reaction of following compound follows (A) Ethene > Propene (B) Methoxyethene > Chloroethene (C) Phenylethene > Cyclohexylethene (D) Ethene > Ethyne 8.
CH3 –O–CH=CH 2 I
F–CH=CH2 II CH=CH2
CH3–CH=CH2 III
IV 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
CH3 CH2=CH2 CH2=CH–CHO CH3–CH 2–CH=CH2 CH –C=CH 9. 3 2 I II III IV Rate of addition of Cl2 / H2O of the following alkenes is
(A) IV > III > I > II (C) I > II > III > IV
(B) IV > III > II > I (D) I > II > IV > III
10. Which of the following reactant is most reactive towards electrophilic addition reaction with HBr. (A)
(C)
10
Ph
Ph
Ph Ph
(B)
OCH3
(D)
CH 3
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Alkene & Alkyne HBr Major product
11.
CH2Br
(A)
(B)
CH 3 Br
CH3
Br
(C)
Br
(D)
HCl Major product
12.
H CH 2–CH2–Cl
Cl–C–CH3
(A)
(B)
Cl
CH2–CH3 CH2–CH3
(C) 13.
(D) CH=CH CH–CH 2
(A)
Br
HBr
Cl
Major product (B)
CH 2–CH Br
Br
Br
(C)
CH=CH
(D)
CH=CH
14. F3C – CH = CH2 + HCl Major product H
(A) F3 C–C–CH 3 Cl (C)
F3C–CH–CH 2 Cl
Cl
(B) F3C – CH2 – CH3
(D) F3CCH2CH2Cl
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11
Alkene & Alkyne CH 2 HBr
15.
X (major product)
X will be CH 2 –Br
(A)
(B)
CH 3
(C)
CH 3 Br
CH 3
Br
(D) Br
16. Major product X, Y, Z obtained in the following reaction is: CH3
HBr H2O
X
HBr CH 3OH
Y
HBr D 2O
Z
(A)
OH CH 3 ,
OD CH 3 ,
OCH 3 CH 3
(B)
OH CH 3 ,
OCH 3 CH3
OD CH 3
Br
(C)
(D)
12
CH 3
OH CH 3
,
in all reaction
in all reaction
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Alkene & Alkyne 17. Which of the following is/are the major product(s) of the following reaction? CH 3 CH= C
HBr
?
CH3
CH 3
CH=CH
(A)
CH2 –C Br
(B)
Br
CH 3
CH 3 CH=C
(C)
CH=C
(D)
Br
Br
18. In which of the following alkenes will a hydrogen shift occur upon addition of HBr? (A)
(B)
(C)
(D)
19. The product of following reaction can be : OH
HBr
CH=CH 2
H3 C
CH 3
(A)
H3 C
OH
OH
(B)
CH3
CH 3
CH 3 H3 C
(C)
O CH2
(D)
O CH 3
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Alkene & Alkyne HCl 20. Ph–CH=CH–CH 3
The major product of given reaction will be Cl (A) Ph–CH –CH=CH 2 3
(C)
Cl
(B)
CH=CH–CH3 Cl
Ph–CH–CH 2 –CH 3
(D) Cl
CH=CH–CH3
CH 3
21.
HBr
CH2 –Br
(A)
(B)
CH 3 Br (C)
CH 3
(D) Br
HCl
22. CH 3
X (major product)
(A)
(B) CH 3Cl
Cl
(C)
Cl
(D) Cl
CH3 HCl
23. OH
X (major product)
Major product X will be Cl
Cl
(A)
(B) Cl
Cl
(C)
14
(D)
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Br
Alkene & Alkyne 24. Which of the following reaction results in the formation of pair of enantiomers on treatment with HBr (A)
(B)
(A)
(B)
(C)
(D) O 25. Which of the following reaction results in the formation of a pair of diastereomers on treatment with HBr (C) (D) Ph 26. How many transition state and intermediate will be formed during the course of following reaction. Br HBr
(A) 3 TS & 3 intermediate
(B) 4 TS & 3 intermediate
(C) 3 TS & 2 intermediate
(D) 3 TS & 4 intermediate
Et Me
27.
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
Cl
28.
HCl
X
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
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Alkene & Alkyne 29. Which reaction will occur at the fastest rate. HBr
Br
HBr
(A)
(B) Br
(C)
HBr
Br HBr
(D)
Br 30. 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 dia gra m best describes the electrophilic addition 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
HCl
33.
Cl
The intermediate formed in given reaction will be (A) 34.
.
(B)
(C)
(D)
Cl
HCl
The carbocation which is not formed at all in given transformation reaction is (A)
16
(B)
(C)
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(D)
Alkene & Alkyne HCl
35.
?
Which reaction mechanism is most likely to occur during this reaction. Cl
H+
(A)
Cl
Cl
(B)
H+
(C)
H
(D)
Cl
+
Cl
H+
Cl
Cl
Cl H+
36.
Which of the following energy profile best represents above reaction
Ep
Ep
(A)
(B) Overall reaction
Overall reaction
Ep
Ep
(C)
(D) Overall reaction
Overall reaction
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Alkene & Alkyne 37. What is/are the product(s) from the following reaction? CH 3 + HCl
CH 3 Cl
?
CH 3
Cl
(I)
(A) I only
(B) II only
(C) I is minor, II is major
(D) I is major, II is minor
dil.H SO
38.
4 2
CH 3
HO
OH
OH (B)
(A) 39.
(II)
(C)
OH (D)
dil.H SO
2 4 X (major product) Major product X is :
CH 3
CH 3 OH
(A)
(B) OH OH
OH CH 3
(C)
dil.H 2SO 4
40.
CH 3
(D)
CH=CH–CH3
X (major product)
Major product X will be : (A) only
(B) only CH2–CH–CH3 OH
(C) (A) and (B)
18
CH–CH 2–CH3 OH
(D)
OH CH2–CH 2–CH3
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Alkene & Alkyne dil.H 2 SO 4 41. Ph – CH2 – CH = CH2
(A)
(C)
Ph–CH–CH 2 –CH 3 OH Ph–CH–CH–CH 3
(B)
Ph–CH–CH–CH 3 H
OH
(D) Ph – CH2 – OH
OH OH H 2O/H +
42.
The intermediate formed in given reaction will be (A)
(B)
O
(C)
(D)
OH
H dil.H SO
43.
2 4 NO 2
(A) HO
OH
(B)
NO 2
NO2
HO
OH
(C)
(D)
NO2
44. CH 3 –CH–CH=CH 2
NO 2
dil. H 2SO 4
CH3
OH
(A) CH 3 –C–CH 2 –CH 3
H
(B)
CH 3
CH 3
C–CH3
CH3 H
CH 3 –CH–CH 2 –CH2 –OH
(C)
CH 3 –C
OH
(D)
HOCH 2 –CH
CH–CH3
CH 3 H
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19
Alkene & Alkyne CH 3
45.
H
CH 3 Br 2
C=C
H
(X) Product. Value of X is:
(A) 0
(B) 1
(C) 2
(D) 3 H+
46.
CCl 4
HO
X (major product)
Major product X will be (A)
(C)
OD
H
(B)
H 2 O/H +
48.
CH 3
OH
X (major product)
D
(A)
O
(D)
OH D2O/H +
47.
(B)
CH 3
OD
H
(C)
D
OH
(D)
X (major product)
The major product X of the given reaction will be OH
(A)
(C)
20
OH
(B)
OH
(D)
OH
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OH
Alkene & Alkyne 49. Which of the following is among the major products of the reaction of (E)-3-methyl-2-pentene with BH3 in THF followed by the addition of H 2O2//HO– ? OH H
Et
(A) H
Me
(B)
Me H
(C) H
Et Me
OH
H
H
(D) Et
Me Et
50.
Me
H
Me Me
OH H
OH Me
OCH3
(A) CH3 OH / H+
(B) CH3 CH2 OH / H+
(C) H2 O / H+
(D) HOCl / H+
x CH 3 CHCH2 CH3 x will be : 51. CH3 CH = CHCH3
OCH 2 CH3
(A) CH3 OH / H+
(B) CH3 CH2 OH / H+
(C) H2 O / H+
(D) HOCl
H
52. CH 3
(A)
(C)
C=C
H
Br2
C(CH3 )2 CH 2 OH CCl 4
Br CH 3 CH3
O
CH 3
(B)
CH 3
Br CH 3 O CH 3
(D)
H
(A). Product (A) is:
Br H CH 3 O
CH 3 CH 3
O Br
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21
Alkene & Alkyne CH3 H (1) BH 3 ;THF
53.
(A); Product of the reaction is:
(2) H 2O 2 , HO–
(A)
CH 3 H H OH CH 3
54.
CH3 OH H H
(B)
O
(C)
CH 3OH/H
CH 3
H3 C
CH 3 H H H
CH 3 H H CH 3
(D)
+
X (major product)
The major product X will be CH 3
CH 3
O (A) H C 3 OCH3
CH 3
(C)
(B)
CH 3
H3 C
OCH3
OCH 3
CH 3
OCH3
(D) H3 CO
H3 C
55. Ph–CH=CH–CH3
CH 3OH/H +
OCH3
CH 3
X (major product)
The major product X will be (A)
(C)
22
Ph–CH2 –CH–CH 3 OCH3 Ph–CH2 –CH 2 –CH 2 OCH3
(B)
Ph–CH–CH 2 –CH 3 OCH 3
(D) H3 CO
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CH 2 –CH2 –CH 3
Alkene & Alkyne 56. What is the major product of the following reaction? CH 3
Br2
+
H 2O
X (major product)
The major product X will be CH 3 Br (B) OH
(A)
CH 3
CH 3 Br (D)
OH (C) Br
CH 3 OH
57. Which reaction intermediate is formed when Br2/CCl4 reacts with cyclohexene? Br
(A)
(B)
Br
(C)
.
Br
(D)
Br
Br /H O
2 2 58. cis-2-Butene
CH 3 CH 3 CH 3 CH 3 H H OH OH H3 C H C OH 3 Br Br H (C) Br (A) H (B) Br H (D) HO H CH3 CH3 H H
H
Br2 CCl 4
59. H
Product of above reaction is:
(A) meso
(B) racemic mixture
(C) diastereomer
(D) structural isomer
60.
Br2
Br
Br
(A)
(B) Br
Br
Br
(C)
Br
(D)
Br Br
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23
Alkene & Alkyne 61. What is/are the product(s) from the following reaction? + Br2 /CCl 4
?
Br
(I)
(II)
Br Br
(III)
Br
(IV)
Br
(A) I and II
(B) I and III
Br
Br
Br
(C) I and IV
(D) II and III
H N
62.
Br2
X (major product)
Major product X will be H
Br
N
N
(A)
(B) Br
(C)
Br2
N
(D) Br
Br
Br
OH
63.
N
Br
Br
X (major product)
Major product X will be
(A)
O
Br
Br Br
(B)
OH
Br
(C)
O
Br
(D)
O
64. Which compound on reaction with bromine give meso-2,3Dibromobutane as a product. (A)
24
(B)
(C)
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(D)
Alkene & Alkyne CH 3
H
65.
Br2
C2H 5
CCl 4
(Z)
Br
Br
(A)
H Br
Br
Br
Br
H Br Br (C) Br (D) H C Br (B) Br 3 C2H 5 H5 C 2 H H5 C 2 Br H5 C 2 Br CH 3 CH 3 CH 3 H Br2 CCl 4
66.
(stereoisomer) ( )
Identify product’s: Et
Et Br
(A)
Br Br
(B)
Br
Br Et
Br
(C)
Br Br
(D) H
67. Which of the following is most reactive toward bromination? (A)
OCH3
(B)
(C)
(D)
CH 3
68.
H C=C
H
(A) 0
Cl
CH3
Br2 CCl 4
(B) 1
(X) products. Value of X is: (C) 2
(D) 3
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25
Alkene & Alkyne 69. Which of the following species is an intermedia te in the reaction shown below? Br
Br2 /H 2O
OH
(A)
(B)
Br+
Br2(1 eq)
70.
(C) O
NH 2
(D)
+
O H
X (major product)
Major product X will be Br N
(A)
N
(B)
H
H
Br
Br
(C)
(D)
NH 2 Br2 (1 eq)
71.
Br
OH
Br NH2
X (major product)
Major product X will be Br
Br
(A)
OH Br
(B) OH
Br
(C)
26
O
(D)
O
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Br
Br–
Alkene & Alkyne COOH
Br2
72.
X (major product)
Major product X will be O
O O
(A)
O
(B)
Br
Br
COOH
O
O
(C)
(D)
Br
Br
Br
SO 3H
Br2
73.
X (major product)
Major product X will be O
O S
(A)
O O
O
(B)
S
O
Br
Br
SO 3 H
(C)
(D)
Br
Br
SO 3H
Br Cl OH
74.
(A) CH3 OH / H+
(B) CH3 CH2 OH / H+
(C) H2 O / H+
(D) HOCl / H+
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27
Alkene & Alkyne 75. Which statement is correct for iodolactonization reaction (A) It is the organic reaction that form a lactone by the addition of an oxygen and iodine across a carbon-carbon double bond. (B) It is the organic reaction that form acyclic amide by the addition of an oxygen and iodine across a carbon-carbon double bond. (C) It is the organic reaction that form acyclic ester by the addition of an oxygen and iodine arcoss a carbon-carbon double bond. (D) It is the organic reaction that form lactum by the addition of a n oxygen and iodine arcoss carbon-carbon double bond. 76. The intermediate formed in halolactonization reaction is (A) Carbocation
(B) Cyclic halonium ion
(C) Carbanion
(D) Free radical
COO – I 2 /NaHCO 3 CH 2Cl 2
77. CH3 CH 3
X (major product)
X (major product) O
O O
(A)
O H
I–H 2 C
CH 3 CH 3
(B)
H
O
O
O
(C)
28
O H
IH2 C
CH 3 CH 3
I–CH 2
CH 3 CH 3
(D)
H
CH 2 I
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CH 3 CH 3
Alkene & Alkyne 78. Which is incorrect among these? COOH
(A) Ph
O I2 /NaHCO 3
O
CHCl 3 0°C, 6H
COOH
(B) Ph
Ph
I O
I2 MeCN 0°C, 24H
O Ph
I (C) Formation of cis product is kinetic product while trans product is thermodynamic product.
(D) Formation of cis product is thermodynamic product while trans product is kinetic product. O
OH i) NaHCO 3
79.
ii) I2 , KI, 0°C
O
X (major product)
Major product x will be O
O
O
O
(B) I
(A) I
O O
O
O
O
I
(C)
I
(D) O
80.
OH
Br2 CH 2Cl 2
X (major product)
Major product X will be (A) Br
Br
(B) O (C) Br OH
O
Br (D)
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O
Br
29
Alkene & Alkyne 81. Which will not be the product of given reaction OH
(A)
Br2 /H 2O
H Br
O
OH (C) OH
(B)
(D) Br
OH
i) Hg(OAc) 2 /H 2O ii) NaBH 4
82.
O
H Br
OH OH
The intermediate of reaction will be
(A)
(B) O
(C)
Hg–O–C–CH 3
(D)
HgOCOCH 3
83. Which of the following sta tement is wrong a bout oxymercuration-demercuration reaction of alkene. (A) In 1 st step, Hg(OAc)2 & H2O adds to C=C double bond. (B) In 2 nd step, NaBH4 reduce –HgOAc group & attached H. (C) The net reaction is a ddition of wa ter according of markownikoff rule. (D) Carbocation is formed in this reaction. CH 3 –CH–CH=CH2
84.
CH3
(i) Hg(OAc)2 /H 2O (ii) NaBH 4
OH
(A)
CH 3 –C–CH 2 –CH 3
H
(B)
CH 3
(C)
30
CH 3 –CH–CH 2 –CH2 –OH CH3
CH 3 –C
OH C–CH 3
CH 3 H
(D)
HOCH2 –CH CH 2 –CH3
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CH 3
Alkene & Alkyne (1) Hg(OAc)2 /THF– H 2O
85.
(2 ) NaBH 4 + OH –
(A)
(B) OH
OH
(C)
(D) all of these
OH CH 3 C–CH=CH2
86.
H
(1) Hg(O 2CCH 3 )2 , H 2 O (2 ) NaBH 4 + NaOH
CH3 H C C – CH3
(A)
H
CH3 H
OH
CH3 H C C – CH3
(C)
C H
(B)
C – CH3 H
CH3 C–CH2 –OH
(D)
CH3
OH H Hg(OAc)2 /H 2O NaBD4
87.
OH
(A)
H H D
(B)
OH
H OH D
OH i ) Hg (OAc)2
88.
ii) NaBH 4
(C)
H
OH
D
H (D)
D
H
X (major product)
Major product X will be OH
(A)
O
(B)
O
(C)
O
(D)
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OH
31
Alkene & Alkyne 89. Which of the following alkene will give Methylcyclohexanol on oxymercuration-demercuration reaction. (A)
(B)
(C)
(D)
O Hg(OAc) 2 /ACOH
90.
X (major product)
Major product X will be
O
O HgOAc
(A)
OAc
(B)
O
OAc HgOAc
O OAc
(C)
(D)
HgOAc
HgOAc OAc (i) BH3 –THF
91.
(ii) H2O2/OH -
(A)
CH3HO
CH 3
(B) H
HO
H OH
(C)
CH3 H H
32
OH
(D)
CH3 H H
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Alkene & Alkyne 92. CH 3 –CH–CH=CH 2 CH3
(i) BH 3 –THF (ii) H 2O 2 /OH
OH
(A) CH 3 –C–CH 2 –CH 3
H
(B) CH 3 –C
CH 3
(C)
CH 3 –CH–CH 2 –CH2 –OH CH3
OH C–CH 3
CH 3 H
(D)
HOCH2 –CH CH 2 –CH3 CH 3
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 (i) BD 3 – THF (ii) H 2O2 / OH¯
94.
(A)
H H D
(B)
OH
H OH D
H OH
(C)
H H
(D)
H OH
H
H
D
BH 3 , THF
95.
H 2O 2 , OH –
(A) (C)
OH
(B) OH
(D)
OH
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33
Alkene & Alkyne BD 3 /THF
96.
H 2O 2 /OH –
(A)
(C)
X (major product)
H
(B)
D D
(D)
OH
X will be
OH D H OD
X OH
97. Y
OH Z OH X, Y, Z reactions are respectively called as
(A) All is simply hydration reaction. (B) Acid hydra tion, Oxymercura tion-demercura tion, Hydroboration-oxidation. (C) Acid hydration, Hydroboration-oxidation oxymercuration demercuration. (D) Oxymercura tion-demercura tion, oxidation, acid hydration. 98.
CH 3 –CH–CH=CH 2
HBr –20°C
HBr 40°C
Br (A) Both the major product A and B are
Hydrobora tion-
CH3–CH=CH–CH2–Br (B)
(A) Kinetically controlled product (B) Thermodynamically controlled product (C) A is thermodynamica lly controlled & B is Kinetically controlled. (D) A is kinetically, B is thermodynamically controlled
34
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Alkene & Alkyne HCl (1 eq)
99. Cl
Cl
(A)
(C)
(B)
(D)
Cl
Cl
100.
HBr / R2O 2
CH=CH CH–CH2
(A)
(B)
CH 2 –CH
Br
Br
Br
Br
CH=CH
(C)
(D)
CH=CH
101. What is the major product of the following reaction? CH 3
HBr Peroxide
?
Br
(A)
CH 3
(B)
CH 3
(C)
(D) Br
CH 2 Br
CH 3 Br
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35
Alkene & Alkyne 102. Which of the following is a step in the mechanism of the reaction shown? CH 2 =CHCH 3 + HBr
Peroxide
CH 2 CH 2 CH 3 Br
.
(A)
(C) 103.
CH 2 CHCH 3 + HBr Br
CH 2 CHCH 3 + HBr Br
(B)
.
CH 2 CH 2 CH 3 + HBr
(D) CH 2 CH 2 CH 3 + HBr
I – Cl
The intermediate of given reaction will be (A) (C) 104.
(B)
I
Cl
Cl
(D)
I
HOCl
The intermediate of given reaction will be
(A)
O
(B)
Cl
H
(C) 105.
Cl
(D)
OH
NBS
The intermediate of given reaction will be (A)
36
(B)
(C)
.
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(D)
Alkene & Alkyne 106.
NOCl
The intermediate of given reaction will be (A)
(C)
(B)
NO
N
NO
(D)
Cl
O
107.
Cl–CN
The intermediate of given reaction will be (A)
(C)
(B)
Cl
CN
(D)
Cl
N
C
NBS 108. CH 3 –CH=CH 2
(A) CH 3 –CH2 –CH 2 –Br
(B)
CH 2 –CH=CH 2 Br
(C) CH 3 –CH–CH 3 Br
(D) CH 3 –CH–CH 2 Br
Br
Cl /CCl
2 4 109. trans-2-pentene
CH 3 H Cl (A) Cl H C2H 5
CH 3 CH3 CH3 H Cl H C 2 H5 H C 2 H5 (B) H Cl (C) Cl (D) Cl H H C2H 5 H Cl
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37
Alkene & Alkyne 110. 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
OH
111.
CH 3CHCH 2 CC CH3
(A)
CH
H 2O.H 2SO 4 HgSO 4
CH3
O
CH 3 –CH–CH 2 –C=CH–C–H CH 3
CH3
OH O
(B)
CH 3 –CH–CH 2 –C CH 3
C–CH 3
CH 3 OH
(C)
CH 3 –CH–CH 2 –C – C=CH 2 CH 3
CH 3 OH OH
(D)
CH 3 –CH–CH 2 –C–CH=CH CH 3
CH 3
OH –
BH3 , THF H2O 2 /OH 112. CH 3 CH 2 CH 2 C CH
(A) CH3 CH2 CH2 CH2 – CHO
(B)
CH 3 CH 2 CH 2 CCH2 O
(C) CH3 CH2 CH2 CHO
(D) CH 3 CH 2 C–CH2 CH 3 O
38
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Alkene & Alkyne Br2 (1 eq.)
113. CH2 = CH – CH = CH – CH = CH2
(60–80°C)
X Major
(A) BrCH2 –CH=CH–CH(Br)–CH=CH 2 (B)
BrCH 2 –CH=CH–CH=CH–CH 2 Br
(C) CH2 =CH–CH(Br)–CH(Br)–CH=CH2 (D) BrCH2 –CH(Br)–CH=CH–CH=CH 2 HCl (1 eq)
114. (A)
Cl
(B)
115. C3 H7 C CH
Cl
HBr peroxide
(C)
Cl
(D)
Cl
‘X’ X is -
(A) C3 H7 CH = CHBr
(B) C3 H7 CBr = CH2
(C) C 3 H 7 CBr C – Br
(D) C3 H7 CH2 –CHBr2
|
H
C
116.
CH Br2 , H 2O
Br
O C
(A) Br
(C)
CH
CH 2 Br2
(B)
Br
CH C
C
(D)
Br
C
CH
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39
Alkene & Alkyne MeOH H 2SO 4
117. CH2 = CHCHOHCH = CHMe
(A) CH2 = CHCHOHCH2 CH(OMe)Me (B) CH2 = CHCH = CHCH(OMe)Me (C) CH2 = CHCH = CHCH2 Me (D) CH3 – CH (OMe) CH = CHCH(OMe)Me 118. What is the kinetic product for the following reaction? CH 3 + HCl ? CH 3 Cl CH 3 Cl CH 3 (A) (B) (C) (D) CH 3 Cl Cl 119. What is the major organic product of the following reaction? Hg 2+
CH H SO 2 4
H
O
(A)
(B)
OH H
(C)
H O
H
(D)
H HO
120.What reagents can best be used to accomplish the following transformation? OH
(A) 1. BH 3 , THF 2. HO – , H 2 O 2 (B) H , H 2 O (C) 1. Hg(OAc)2 , H 2 O/THF 2. NaBH 4 (D) 1. Hg(O2 CCF3 )2 , CH 3OH 2. NaBH 4
40
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Alkene & Alkyne
Multiple Correct Questions (MCQ) : 121. The a lkenes which a re more rea ctive than ethene for electrophilic addition reaction are (A) CH2 =CH–Cl
(B) CH3 –O–CH=CH 2
(C) CH3 –CH=CH 2
(D) CH2 =CH–CHO
122. Which of the following compounds will give same major product on acid catalysed hydration CH 3
(A)
CH 3
Ph–C–CH=CH 2
Ph–CH–C=CH 2
(B)
CH 3 CH 3
(C)
Ph
C=C
CH 3 Ph
CH 3
CH 3
(D)
CH 3
CH 3
CH
C=CH 2
123. The correct products have been reported in reactions. (A)
(B)
CH 2 =CH–CHO
(H Cl(g)(–10°C)
Cl
CH 2 =CH–COOH
H 2 O/H 2 SO 4
CH 2 –CH2 –COOH OH
CH 3
(C)
CH 2 –CH 2 –CHO
CH 3 –C=CH–C–CH 3
CH 3OH H 2SO 4
CH 3 CH3 –CH–CH – C –CH 3
O
(D)
CH 3 –CH=CH–OCH3
OCH3 O CH 3OH/H +
CH 3 –CH2 –CH–OCH3 OCH 3
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41
Alkene & Alkyne 124. 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)
(E)
CH(OH)CH2 D (P)
CH=CH 2
(II) (III)
OH (F) CH2 D CHDCH 2 OH
(G)
(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) a re formed via free radical, carbocation and cyclic carbonium ion intermediate respectively. (D) Products (E), (F) and (G) are formed via mercury-bridged carbocation, carbocation and four-centre transition state respectively. H , H2 O
125.
Possible products of the reaction will be
OH
(A) OH
(C)
42
OH
(B) OH
(D)
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Alkene & Alkyne 126. In which of the following reaction(s), major product is formed by the cyclic intermediate of reactive intermediate? (A)
+ HCl
(B)
+ Br2 –H2 O
(C)
+ (CF3 COO)2 Hg
(D)
H 2O
NaBH 4
+ HBr
127. Which of the following is correct sta tement a bout oxymercuration-Demercuration(A) In the I st step oxymercuration occurs i.e. wa ter & 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 rea ction is addition of wa ter a ccording to Markonikoff rule (D) Rearrangement takes place 128. In which of the following halogen addition reaction, racemic mixture of products is formed? (A) (B) (C)
+ Br2 –CCl 4
FeCl 3
+ Br2 –CCl 4
+ Br2 –CCl 4
FeCl 3
FeCl 3
(D) CH 3 –CH=CH2 + Br2 –CCl 4
FeCl 3
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43
Alkene & Alkyne 129. Consider the following a ddition reaction on a pure enantiomer of the shown bromoalkene. CH 3 H Br + HBr CH=CH2
Products(s)
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 rule 131. When But-2-yne is brominated, P is formed. When But-2-yne is reacted with HgSO4 + H2SO4, then Q is formed. Which statement 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? hv + NBS CCl 4 (NBS=N-bromosuccinimide)
Br
(A)
44
Br (B)
Br
(C)
(D)
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Br
Alkene & Alkyne 133. Predict products(s) in the reaction + HBr
Br H
(A)
(B) Kinetically controlled
Br
Br Kinetically controlled
Br (D) Thermodynamically controlled
(C) Thermodynamically controlled
134. The correct statement(s) regarding following reaction is/are CH2 =CH–CH=CH 2 HBr CH 2 =CH–CH–CH3 CH 2 –CH=CH–CH 3
I
Br
Br
II
(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 a re a lways formed in comparable amounts (D) Product I isomerises into II on heating above 40°C 135. The correct sta tement(s) regarding 1,2-buta diene(I) a nd 1,3-butadiene, (II) is/are CH2 =C=CH–CH3 (I)
CH2 =C–CH=CH 2 (II)
(A) I ha s perpendicular pi planes while II has para llel pi planes (B) Both gives the same product on adding 1.0 equivalent at HBr of –80° C (C) I gives 2 ,2 -dibromobuta ne while II gives, 2,3-dibromobutane, when reacted with excess of HBr at very low temperature (D) Both have same length of C=C double bonds
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45
Alkene & Alkyne 136. 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) Hydrobora tion oxida tion over propene lea ds to propan-1-ol as major product. 138. In which case carboca tion is not formed a s 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. Cl
(A)
HOCl
NO NOCl
(B) OH
Cl
I
(C)
I–Cl
CH 3OH H
(D)
+
OCH3
Cl
140. In which case rearrnage product will be major one. (A) (C)
46
CH 3OH/H
H 2O/H +
(B)
HBr +
(D)
Ph
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Br2
Alkene & Alkyne 141. Addition of HCl to 3,3-dimethyl-1-butene yields two products, one of which has a rearranged carbon skeleton. Among the following carbocations, select the possible intermediates in that reaction?
(A) (CH 3 )3 C C HCH2 Cl
(B) (CH 3 )3 C C HCH3
(C)
(CH 3 )2 CC(CH3 )2 |
Cl
(D) (CH 3 )2 C CH(CH 3 )2
142. In the addition of HBr to 1,3-butadiene, one product is called the kinetic product and the other is called the thermodynamic product. Which of the following descriptors applies to the kinetic 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 a lkenes yield(s) 3 -bromo-3 methylpentane as the major product upon addition of HBr? (A)
(B)
(C)
(D)
CH 3 CHCH=CH2
144.
A
(A) H 2 O/H +
CH 3 CH–CHCH 3 OH
; Reagent A may not be:
(B) BH 3 .THF/H 2 O 2 –OH–
(C) Hg(OAc)2 .H 2 O/NaBH 4 (D) BH 3 .THF/H 2 O 2 –AcOH
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47
Alkene & Alkyne 145. Which series of reactions will not achieve the following transformation? Br 1
2
Cl Cl
(A) Cl 2/CCl4
Br2
(B) HBr
Cl2/CCl4
(C) Cl2/CCl4
NBS/hv
(D) NBS/hv
Cl2/CCl4
COOH
146. HOOC
Br2 CCl 4
(P)
HOOCCH(Br)CH(Br)COOH (X)
Br
HOOC
2 COOH CCl 4 HOOCCH(Br)CH(Br)COOH (Q) (Y)
The correct statements with respect to the above pair of reactions 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) OH
147.
Br2
(A) Br
(C) Br
48
HBr + (P)
Cl
O Cl P O OCH 3 Q
MeOH
(Q) product P,Q will be O
(B) P
Br
O
(D) Q
OCH 3
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Alkene & Alkyne 148. Select the reaction(s) that would result in the formation of 2bromopropane. peroxide (A) CH 3 CH=CH2 + HBr
CCl 4 (B) CH 3 CH=CH2 + HBr
hv (C) CH 3 CH 2 CH 3 + Br2 CCl 4 (D) CH 3 CH=CH2 + Br2
149. The major product of the reaction given below is : OH
(A) Br
(C)
O
Br2 H 2O
?
OH
(B) HO
OH
H
(D)
CH 2 –Br
O
Br OH
CH2 –Br H
150. Which of the following compounds gives the sa me carbocation on ionization? (A)
Br
(B)
Br
(C)
Br
(D)
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Br
49
Alkene & Alkyne
Assertion / 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 – methylcyclopenta ne yields 1 –chloro–1 ,2 , 2–trimethylcyclohexane. Reason:
Mechanism of reaction is CH 3
H+
CH 3 CH 3 and
152. Assertion:
Cl Cl
CH 3
CH 3 CH3
on hydra tion
give same alcohol. Reason:
The intermediate carbocation for both the alkenes is same.
153. Assertion: The addition of CBrCl3 in the presence of peroxides takes place faster to 2-ethyl-1-hexene than to 1-octene. Reason:
Due to formation of 1° free radical in case of 2 ethyl-1-hexene
154. Assertion: The hydroboration oxidation of D D
Reason:
50
gives
H
OH D D
The syn addition of BH3 across the double bond of norbornane takes place mostly from the more accesible outside face of the double bond.
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Alkene & Alkyne 155. Assertion: The addition of chlorine to cyclohexene gives a racemic mixture of trans-1, 2-dichlorocyclo hexane. Reason:
The trans-1, 2-dichlorocyclohexane is less sterically crowded than cis-1, 2-dichlorocyclo hexane hence easily formed.
156. Assertion: Acteylene is less reactive than ethylene towords electrophilic reagents. Reason:
p–electron density in a triple bond is higher than that in a double bond.
157. Assertion: The predominant product in the addition of halogens to acetylene is the trans isomer. H I C=C Reason: The addition of I2 to acetylene gives I H as the major product. 158. Assertion: When acetylene is passed into hyochlorus acid solution dichloroacetaldehyde is formed. Reason:
The process of reaction is H H–C
C–H + H–O–Cl
H–C=C
HO HO–Cl
Cl–C– C–H + H 2O
ClOH
Cl
159. Assertion: 2–Bromo–1–butene reacts with HBr to give 2,2– dibromobutane. Reason:
The intermediate carbocation formed is stablished by +m effect of Bromine atom.
160. Assertion: With the use of BD 3 /THF a nd CH 3 COOH, 2-Butyne gives Cis-2-deutero-2-butene. Reason:
The same product is obtained when the reagent used is BH3 /THF and CH3 COOD.
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51
Alkene & Alkyne
Match the Column type Questions (MTC) : 161. Match the column: (A)
HBr Peroxide
(P)
(B)
HBr No Peroxide
(Q)
Br
(C)
HCl Peroxide
(R)
Cl
(D)
HCl CCl 4
(S)
(E)
NBS
(T)
Br
Cl Br
162. Match List-I with List-II and select the correct answer using the codes given below the lists: List-I (Reaction)
List-II (Reagents)
(A) CH 3–CH=CH2 CH3–CHBr–CH3
(P) HBr
(B) CH3–CH=CH2 CH3–CH2–CH2Br
(Q) Br2
(C) CH3–CH=CH2 BrCH2–CH=CH2
(R) HBr/Peroxide
(D) CH3–CH=CH2 CH3–CHBr–CH2Br (S) NBS 163. Match the column: (A)
HBr Proxide
(P)
Electrophilic-addition reaction
(B)
HCl Proxide
(Q)
Free-radical-addition reaction
(R)
Free-radical-substitution reaction
(S)
Electrophilic substitution reaction
CH 3
(C) (D)
52
NBS
Cl 2 /AlCl 3
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Alkene & Alkyne 164.
Column-I
Column-II Cl
Cl 2 ,CCl 4
(A)
P.
Rearrangement
Cl Cl 2 ,hv
(B) Br
(C)
CH 3OH Δ
(D)
H /H 2O
165.
Cl
OH
Q. Carbocation
R.
Free radical
S.
Cyclic intermediate
Column-I
Column-II
Markownikoff (A) product
P. CH 3 –CH=CH 2 H2O 2 ,hv
Anti-Markownikoff (B) product
Q.
(C) Peroxide effect
R.
(D)
Mixture of stereoisomers
HBr
H3 C H
C=C
CH3 CHCl +KOH 3 H
CH=CH 2 HBr
S. CF3 –CH=CH 2 HBr
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53
Alkene & Alkyne
Comprehension type Questions : Passage : 1 In electrophilic addition rea ction, a lkene behave a s a nucleophile or base. During reaction electrophile react with a lkene in ra te determining step to form carboca tion according to markownikoff rule. In second step carbocation react with nucleophile to give product so overall addition reaction take place. 166.
+ Br2
CCl 4
Number of product (including stereo) formed in the reaction: (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 : 2 Homolytic bond fission of a covalent single bond gives rise to free radicals. Owing to the presence of an odd electron, free radicals are highly reactive. They have planar to pyramidal geometry depending upon the groups attached to the C-atom having odd electron. Alkyl free radicals are stabilised by hyperconjugation whereas allyl and benzyl free radicals are stabilised by resonance. They are formed as intermediates in the reaction mixture either in the gaseous phase or in nonpolar solvents. Addition of HBr to alkenes in presence of peroxide, the substitution of allylic or benzylic hydrogen by ‘Cl’ at high temperature or by ‘Br’ in presence of NBS are examples of reactions involving free radical intermediates. Now answer the following questions :
54
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Alkene & Alkyne 168. 3,5-dimethylcyclopentene reacts with N-bromosuccinimide (NBS) in CCl4 in presence of light or peroxide. Identify the product. H3 C
CH 3 + NBS
(A)
(C)
H3 C
hv
Expected Product H3 C
CH 3 Br
H3 C
CH 3
(B) Br
H3 C CH 3 (D) Br Br
CH 3 H3 C Br &
CH 3 Br
169. Arrange the following free radicals in the decreasing order of their stability.
.
.
. .
CH 2 =CH–CH2 ; (CH 3 )3 C; CH 2 =CH; CH 3
.
.
.
.
.
.
(A) (CH 3 )3 C > CH 2 =CH–CH 2 > CH 2 =CH > CH 3
.
.
.
. .
.
.
.
(B) (CH 3 )3 C > CH 2 =CH–CH 2 > CH 3 > CH 2 =CH (C) CH 2 =CH–CH 2 > (CH3 )3 C > CH 3 > CH 2 = CH
.
.
(D) CH 2 =CH–CH 2 > (CH3 )3 C > CH2 =CH > CH 3 Passage : 3 Addition of HX on alkene proceed through the formation of carbocation. This reaction is also known as Markownikoff reaction. According to Markownikoff’s rule addition of electrophile occurs on that carbon of alkene which have more number of ‘H’ atom. X Ph–CH=CH 2
HX
Ph–CH–CH 3 + Ph–CH2 –CH 2 –X Major Minor
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55
Alkene & Alkyne Mechanism : H
H–X Ph H
H –X
C=CH 2
Ph
H
C–CH 3 + Ph–CH 2 –CH 2 H More stable Less stable
H
X
Ph
Ph C–CH 3 + X
C H
X +
Ph C
CH 3 H 3C Enantiomer
H
170. Which of the following alkene can produce diastereomers ? (A) CH 3 –CH=CH–CH3 H
(C)
(B)
CH 3 CH 3
CH=CH–CH3
(D) CH3 CH=CH2
171. Which of the following alkenes will give Markownikoff reaction ? HCl (A) F3 C–CH=CH 2
HCl (B) H 3 C–CH=CH 2
HBr (C) O 2 N–CH=CH2
(D)
CH 3 CH3
HBr C=CH 2
Passage : 4 Hydroboration oxidation reaction is a process of addition of H2O according to Markownikoff’s rule but product resemble Anti-Markownikoff of product. CH 3CH=CH 2
BH 2.THF H 2O 2 , OH
CH 3 –CH 2 –CH 2 –OH
Rea ction is regioselective, Regioselectivity of reaction in increased by using hindered boranes. THF (Tetrahydrofuran) is used to control reactivity of borane.
56
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Alkene & Alkyne BD 3.THF
172.
CH 3 D OH CH3
(A)
(C) H
H
(B) H
CH 3 OH D
HOOC
173.
Major product :
H 2O 2 ,OH
(D) H
C=C
CH 3 D OH
CH 3 OH OH H
BD 3.THF
COOH D 2O 2 ,OH
COOH COOH COOH COOH H D H OD D H H D (A) H OD (B) H D (C) H OD (D) H OH COOH COOH COOH COOH
Passage : 5 To predict relative reactivities of various positions in a given molecule two different methods are generally used. (i). Predictions based on charge distributions:- This approa ch assumes that the reactivities of a position in a polar reaction is determined by the cha rge density at that position, i.e. an electrophilic reagent will attack preferentially at the site of highest electron density and a nucleophilic reagent will attack preferentially at the site of lowest electron density. The charge distribution is a scerta ined by the exa mina tion of the consequences of inductive and/or resona nce effect. This approach is referred to as the isolated molecule method. (ii). Predictions based on stabilities of intermediates:- This method assumes that the reactivities of different positions in a given molecule are determined only by their relative activation
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57
Alkene & Alkyne energies. Since the activation energy depends on the structures of the transition state. For the reactions that are belived to involve intermediate carbocation, carbanion and free radicals, it is these that are chosen to represent the structure of transition states, the stabilities of which are then examined in terms of inductive effect and/or resonance effect. The assumption is then made that the more stable the intermediate (i.e. the lower its energy), the lower is the energy of TS and consequently the lower 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 over alkene. (A) CH2 =CH 2
(B) CH2 =CH–Cl
(C) CH2 =CH–OCH3
(D) CH 2 =CH–NO 2
175. In which molecule most stable intermediate will be formed after protonation.
(A)
58
(B)
O
O
(C)
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Cl
(D)
Cl
Alkene & Alkyne
Integer type Questions : 176. How many of the following reactions, leads to the formation of diastereomers. (A)
H3 C
HCl
H
Ph
(C)
HBr
C=CH2 CCl 4 H
HBr CCl 4
(B)
C=CH–CH 3 CCl 4 H
(D)
CH3 HCl D CCl 4 CH CH Ph
CH 3
(E)
CH 2
Ph HCl CCl 4
HCl CCl 4
(F) CH 3
177. Identify number of chiral centers present in product obtained by following reaction. Br2 CCl 4
CH 3
H
178. How many different products (excluding stereoisomer) can be obtained by following reaction. HCl, CCl 4
179. If a pure enantiomer of 5-bromo-2-hexene is treated with Br2–CCl4, how many different tribromides would be formed? 180. If a racemic mixture of 3-methyl-1-pentene is treated with HCl, how ma ny different chloropenta ne (importa nt products only excluding stereo) would be formed?
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59
Alkene & Alkyne
Exercise
03 World of competitions 1. What is the product when acetylene reacts with hypochlorous acid ? [AIEEE 2003] (A) CH 3 COCl (C) Cl 2 CHCHO
(B) ClCH 2 CHO (D) ClCHCOOH
2. Rea ction 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 the formation 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
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Alkene & Alkyne 4. HBr reacts with CH2 =CH–OCH3 under anhydrous conditions at room temperature to give [AIEEE-2006] (A) CH3 CHO and CH 3 Br (B) BrCH 2 CHO and CH 3 OH (C) BrCH 2 –CH2 –OCH 3 (D) H 3 C–CHBr–OCH3 5. Acid catalyzed hydration of alkenes except ethene leads to the formation 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 tra ns-2-butene yields meso-2. 3-dibromobutane. [IIT-JEE 2001] Reason:
Bromine addition to an alkene is an electrophilic addition
(A) Assertion is True, Rea son is True, Rea son is correct explanation for Assertion. (B) Assertion is True, Reason is True, Reason is NOT a correct explanation for Assertion. (C) Assertion is True, Reason is False. (D) Assertion is False, Reason is True. HgSO
4 A 7. C 6 H5 – C C – CH 3 H2 SO 4
[IIT-JEE 2003]
O
(A)
(C)
(B) C 6 H5 – C=CHCH 3 OH
(D)
O
C 6 H5 – CH=C–CH 3 OH
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61
Alkene & Alkyne 8.
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), C 5H10O reacts with dil. H2SO4 to give (Q) and (R). Both (Q) and (R) give positive iodoform test. The reactivity of organic compound (P) is 1015 times more than ethylene 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. CH 3 –CH=CH 2 + NOCl P
[IIT-JEE 2006]
Identify the adduct (A)
CH 3 –CH–CH 2 Cl
NO
(B)
CH 3 –CH–CH 2 NO Cl
NO
CH 2 –CH2 –CH 2 (C) CH 3 –CH 2 –CH (D) NO Cl Cl 11. The number of stereoisomers obtained by bromination of trans-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] RCH 2OH O
H (anhydrous)
(A) a hemiacetal
(B) an acetal
(C) an ether
(D) an ester
13. In the hydroboration-oxida tion rea ction of propene with diborane, H2 O2 and NaOH, the organic compound formed is: [IIT-Mains 2014] (A) CH3 CH 2 OH
(B) CH3 CHOHCH3
(C) CH 3 CH 2 CH 2 OH
(D) (CH 3 )3 COH
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Alkene & Alkyne CH2 –CH 2 =CH 2 on mercura tion-demercura tion pro-
14.
duces the major product: CH2 –CH–CH3
(A)
OH
CH2 –CH–CH2
(C)
OH OH
[IIT-Mains 2014] CH2 –CH 2 –CH2 –OH
(B)
CH 2 –COOH
(D)
15. In the following reaction, the major product is CH3
[IIT-Adv. 2015]
CH 2 1 equivalent HBr
CH3
(A) H2 C
CH 3
CH 3
(B)
Br
H3 C Br
CH3
(C)
CH3
H2 C
(D)
Br
H3 C
Br
Comprehension: In the following reactions C 8 H6
[IIT-Adv. 2015]
i. B H
Pd-BaSO 4 H2
C8 H 8 ii. H2 O6 , NaOH , H O X 2 2 2
H 2O HgSO 4 , H 2SO 4
C 8 H8 O
i. EtMgBr, H 2O ii. H + , heat
Y
16. Compound X is: O
(A) (C)
OH CH 3
OH
(B)
CH 3
(D)
CHO
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63
Alkene & Alkyne 17. The major compound Y is: CH 3
(A) CH2
(C)
CH 3
(B)
CH 3
CH 3
(D)
CH 3
18. Anti-Markownikoff addition of HBr is not observed in : [CET (J & K) 2012] (A) 2-butene
(B) 1-butene
(C) propene (D) 2-pentene
19. 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 of HgSO4, 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 rea ctions 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 active alcohol when treated with H2O/H2SO4? [CPMT 2004] (A) 1-Butene
(B) Ethene
(C) Propene
(D) 2-Methyl propene
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Alkene & Alkyne 24. 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 hydration of 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 ma jor product): [AIIMS 2005] (A) C 6 H 5 CH 2 CH(Br)CH3
(B) C 6 H 5 CHCH(Br)CH 2 CH3
(C) C 6 H 5 CH 2 CH 2 CH 2 Br
(D) C 6 H 5 CH(Br)CH = CH2
27. Trans-2-butene-Br2 gives:
[CET (Gujarat) 2006]
H (A) H
CH 3 Br Br CH 3
Br (B) H
CH 3 H Br CH 3
Br (C) H
CH3 Br H CH 3
H (D) Br
CH 3 Br H CH3
28. Reaction of acetylene and propylene with HgSO4 in presence of HgSO4 produces respectively: [BHU (Med.) 2006] (A) acetone and acetaldehyde (B)
acetaldehyde and acetone
(C) propanaldehyde and acetone (D) acetone and propanaldehyde
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65
Alkene & Alkyne 29. Predict the product ‘C’ obtained in the following reaction of 1butyne: HI CH3 CH 2 C CH + HCl (B) (C)
[AIPMT 2007] I
I
(A) CH 3 CH2 – CH – CH2 Cl
(C)
CH 3 – CH – CH2 CH2 I Cl
30. CH 3 – CH – CH = CH 2 + HBr CH 3
(B) CH 3CH2 – C – CH 3 Cl I (D) CH 2 CH 2 CH 2 – C – H Cl 'A' ,
‘A’ (predominantly) is:
[AIPMT 2008]
(A) CH 3 – CH – CH – CH 3 Br CH 3
(B)
CH 3 – CH – CH – CH 3 CH 3 Br
Br (C) CH 3 – CH – CH 2 – CH2 Br (D) CH 3 – C – CH 2 CH 3 CH 3 CH 3
31. The order of reactivity of the alkenes, (CH 3 )2 C = CH 2 , I
CH3 CH = CH2 , II
H 2 C = CH 2 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 > III 32. Identify the product in the reaction Ph–C
C–Me
H 3O+ , Hg 2 +
[DUMET 2010]
?
(A) PhCH2 CH 2 CHO
(B) PhCOCH2 CH3
(C) PhCH 2 COCH3
(D) PhCOCOMe
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Alkene & Alkyne 33. 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 CH 3 CH 3 – C – CH = CH 2 C2H 5
H 2O / H
+
(A) major product
The major product is :
+ (B) minor product
[AIPMT (Prelims) 2012]
CH 3 (A) H3 C – C – CH – CH 3 CH 3 OH
(B) H3 C – C – CH – CH 3 OH CH3
CH 3 (C) CH 2 – C – CH 2 CH 3 OH CH 3
CH 3 (D) H3 C – C – CH 2 – CH 2 OH CH 3
CH 3
35. In the reaction with HCl, an alkene reacts in accordance with the Markovnikov’s rule, to give a product 1-chloro-1methylcyclohexane. The possible alkene is : [AIPMT 2015] CH 2
(A)
CH3
(B)
(A)
(B) CH 3
(C) (A) and (B)
(D)
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67
Alkene & Alkyne
Answers 01 Subjective Approach
1. Organic rea ctions 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 π
A– B
σ
σ
C D
(C) Elimination reaction– Here generally old bonds are broken & corresponding a new bonds are formed. A –B
σ
C
σ
A= B+C– D π
D
(D) Rearrangement reaction– Here generally there is change in connectivity of atom. A – B – C A – C – B
2. Rea gents are the a ttacking species which attacks over the substrate. They may be e– rich, e– deficient or odd e– species.
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Alkene & Alkyne –
3. Electrophiles are e deficient attacking species. They have e– deficiency in the form of either (A) Positive charge
(B) Incomplete octet or
(D) Vacant orbital Those factors which withdraws e– density from electrophile increases its electrophilicity. 4. Nucleophiles are e– rich attacking species which a ttacks are non-metal. They have complete octet with either presence of lone pair or –ve charge. Those factors which donates e– density towa rds nucle ophilic centre genera lly increa ses its nucleophilicity. 5. Free radicals are odd e– reactive species which attacks over another free radicals or neutra l molecules. Free ra dicals are generally formed by either presence of light, peroxide or high temperature. 6. Leaving groups are those atoms or groups which goes out from substrate from any chemical reaction. Those factors which stabilizes leaving group increa ses its leaving group tendency. O
7.
–
–
O –
OH > Ph–O > CH 3 –C–O > CH 3 –S–O – O
I – > Br– > Cl – > F –
NH 3 H 2 O O
8.
O
CH 3 –S–O – > CH3 –C–O – > Ph–O – > H–O – O I – > Br– > Cl – > F –
H 2 O NH 3
9. Solvents a re the medium in which chemical reaction has to take place. They are of 2 types (A) Polar
(B) Non polar
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69
Alkene & Alkyne Polar solvents are those which have polarity in the molecule such as H2 O, CH3 OH etc. Non polar solvent are those which do not have any pola rity in molecule such a s benzene, cyclohexane. Polar solvent are further of 2 types (A) Polar protic– where H+ can be removed from solvent such as H2 O, NH3 , CH3 COOH (B) Polar aprotic– where solvent do not ea sily loose H+ but have polarity such as CH3 COCH3 , CH3 SCH3 etc. 10. Ba se a re those e – rich species which a tta cks over H + . Nucleophile are those e– rich species which attacks over nonmainly C. Ligand are those e– rich species which attacks over metal. 11. General chemical reaction of alkene & alkynes are electrophilic addition reaction. E CH 3 – CH = CH2 E–Nu
CH3 – CH – CH 2
Nu 12. When unsymmetrica l a lkene or a lkyne rea cts with unsymmetrical reagent in electrophilic addition reaction, then positive part of reagent attached to that carbon which have more number of hydrogen while negative part of reagent attached to that carbon which have less number of hydrogen. This rule is called as Markownikoff rule. E CH 3 – CH = CH2
E–Nu
CH3 – CH – CH 2
Nu 13. Basic concept behind Markownikoff rule is the sta bility of carbocation. HCl CCl 3 – CH = CH2 CCl 3 – CH 2 – CH 2 – Cl (Violation of Markownikoff rule) Cl |
HCl CH3 – CH = CH 2 CH 3 – CH– CH 3
(Follow Markownikoff rule)
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Alkene & Alkyne 14. (A) Bromine water test
(B) Baeyer’s reagent.
15. Dilute alkaline KMnO 4 is commonly called as Baeyer’s reagent. It is used to distinguish sa tura tion & unsa tura tion of carbon-carbon bond. 16. Addition of water to alkene is hydration reaction. Hydration of a lkene ta kes pla ce in a cedic medium & rea ction & mechanism follow as below. Reaction: H2 O/H+
OH |
CH 3 - CH = CH2 CH 3 – CH- CH 3
Mechanism:
CH 3 – CH = CH2
H+
..
CH3 – CH – CH 3
H 2O H+
OH CH3 – CH – CH 3
17. (A) Hydration in acidic medium using H 2 O /H + . (B) Hydrobora tion-oxida tion using B 2 H6 followed by H 2 O2 /OH – .
(C) Oximercuration-demercuration using (Ac2 O)2 Hg / H 2 O followed by NaBH 4 . 18. Oximercuration-demercuration is addition of water to alkene using (Ac2 O)2 Hg / H 2 O followed by NaBH 4 . OH |
i) Hg (OAC)2 /H2O
CH3 – CH = CH 2 CH3 – CH– CH3 ii) NaBH 4
19. Alkoxymercura tion-demercuration is addition of a lcohol using (Ac2 O)2 Hg / ROH followed by NaBH 4 . OR i)(AC2 O)Hg/ROH
|
CH3 – CH = CH 2 CH 3 – CH– CH 3 ii) NaBH 4
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71
Alkene & Alkyne 20. Hydroboration-oxidation is a ddition of water using B 2 H6 followed by H 2 O2 /OH – . i)B H ii) H2 O 2 /OH
2 6 CH3 – CH = CH 2 - CH 3 – CH 2 – CH 2 – OH
21. Hydroboration-oxidation is simply a ddition of wa ter but machanism follow via 4 membered cyclic TS. i) B H or BH
2 6 3 CH3 – CH = CH 2 – CH 3 – CH2 – CH 2 – OH
ii) H2 O 2 /OH
Mechanism: CH3 –CH= CH 2 H – BH2
CH 3– CH H
CH 2
CH 3– CH 2 –CH 2 –BH2
BH 2 (CH 3 –CH 2 –CH 2 )3 B
H O /OH–
2 2 (CH 3 – CH 2 – CH2 )3 B 3 CH 3 – CH2 – CH 2 – OH
As here hydrogen attached as hydride so reaction follows Markownikoff rule but product resemble’s Anti Markownikoff product. 22. Bromination of alkene is simply the addition of bromine to alkene to form dibromoalkane as product. Reaction: Br Br2
|
CH 3 – CH = CH2 CH 3 – CH– CH 2 |
Br
Mechanism:
CH 3–CH= CH 2 Br Br
72
Br CH 3–CH CH 2 Br
Br CH 3– CH–CH 2
(Cyclic bromonium ion)
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Br
Alkene & Alkyne 23.
Br Br2 /CCl 4
CH 3 –CH–CH 2 Br
Br CH 3 –CH=CH2
Br2 /H 2O
CH 3 –CH–CH 2 + CH3 –CH–CH 2 Br
Br Br2 /NaCl
Cl Br
CH 3 –CH–CH 2 + CH3 – CH – CH2 Br
Br Br2 /CH 3OH
OH
OCH 3
Br
CH 3 –CH–CH 2 + CH3 –CH–CH 2 Br
Br
24. Reaction: Br |
HBr CH 3 – CH = CH2 CH 3 – CH– CH 3
Mechanism: Br CH 3 – CH = CH2
H
CH3 – CH – CH 3
Br
CH 3 – CH – CH 3
25. Reaction: OH |
HO–Cl
CH3 – CH = CH 2 CH 3 – CH– CH 2 |
Cl
Mechanism:
CH 3–CH=CH .. Cl
OH
HO CH 3 – CH
CH 2
CH 3 –CH–CH2
Cl
Cl
OH
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Alkene & Alkyne 26. Reaction: Cl |
I–Cl CH3 – CH = CH 2 CH 3 – CH– CH 2 |
I
Mechanism: Cl CH 3–CH=CH 2 .. I
Cl
CH3–CH
CH 2
CH 3– CH–CH2 I
I
Cl
27.
Cl OH 8
I Cl 7 Br
Cl 1
HCl ICl
HOCl H2 O/H+
Br2 / H2O
OH 6 Br2 /CCl4
OH 2
ii) (Ac2 O)Hg/H2O ii) NaBH4 i ) BH 3 ii) H 2O 2 /OH–
Br Br 5
4
OH
OH 3
28. When unsymmetrical alkene is treated with HBr in presence of peroxide then hydrogen will attached to that carbon which have less number of hydrogen while bromine is attached to that carbon which have more number of hydrogen. This concept is a gainst Ma rkownikoff rule so it is ca lled a s Anti-Markownikoff rule. This abnormality was first reported by kharasch so it is called as Kharasch effect. HBr/(Ph C O)2 O
2 CH3 –CH=CH 2 CH 3 –CH2 –CH2 –Br
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Alkene & Alkyne 29. NBS is N-Bromo Succinimide. NBS is used to replace benzylic or allylic H with Br via free radical mechanism. Br |
NBS CH 3 – CH = CH2 CH 2 – CH = CH 2
30. NCS is N-Chloro Succinimide. NCS is used to replace benzylic or allylic H with Cl via free radical mechanism. Cl NCS
|
CH3 – CH = CH 2 CH 2 – CH = CH2
Cl Cl 2
|
31. CH2 – CH = CH 2 CH 2 – CH = CH 2 High T
32. (A)
Br
Br
(B) Br
(C)
(D)
Br
33. Reaction: Cl |
HCl CH3 – C CH CH 3 – C – CH 3 |
Cl
Mechanism: Cl CH 3–C CH
HCl
CH 3 –C=CH 2
Cl
CH 3– C= CH 2
Cl CH 3 –C–CH 3
H
Cl Cl
CH3 – C–CH 3
Cl
34. Reaction: O CH 3 – C
CH
HOCl
CH3 – C – CHCl 2
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Alkene & Alkyne Mechanism:. OH CH 3 –C CH
OH
CH3 –C=CH
.Cl
CH 3 –C = CH
Cl
.Cl
OH
Cl
OH HO
OH
O CH 3–C–CHCl 2
–H2 O
CH 3–C–CHCl 2
OH
CH 3 –C
CH–Cl Cl
OH
O
35. CH 3 – C CH
i) B2H 6 – ii) H 2O 2/OH
CH 3 – CH2 – C – H
36. General hydration of alkyne occur in presence of HgSO4 of along with dil H 2 SO 4 . CH 3–C CH
H 2O/HgSO 4 /H +
O CH3 – C – CH3
Mechanism:
..
H 2O CH 3 –C CH
Hg 2+
O–H
CH 3–C=CH
–H +
CH 3–C=CH2
O CH 3–C –CH3
Hg
37. Mercury sulpha te rea cts with a lkyne a nd form a n intermediate over which water attacks to form product.
..
H 2O CH 3–C
CH
HgSO 4
CH 3–C=CH
O–H CH 3–C=CH 2
Hg Intermediate
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O CH 3–C–CH 3
Alkene & Alkyne Cl
38.
HCl
39.
HCl
Cl
40. Intermediates formed from alkene is generally more stable than intermediate formed from alkyne. So alkenes are more reactive than alkynes. + CH 3–CH=CH 2 E
CH3 –CH–CH 2 E (more stable)
CH 3–C
E+
CH
CH 3–C=CH E (less stable)
41. As alkene, Alkynes & water are electron rich so H+ is added to create electron deficient centre in alkene or alkyne over which water will attack. CH 3–CH
CH2
H+
CH 3–CH–CH 3
+ CH 3–C CH H CH 3–C=CH 2
CH3
CH3
|
42. CH3 – CH – CH2 – CH 2 – OH X CH 3 OH |
O
|
|
43. CH3 – CH – CH– CH 3 X
CH3 – CH – CH2 – C – H Y
CH3 |
CH 3 – CH – C– CH 3
O Y
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77
Alkene & Alkyne Br
44.
Br M
Br Br
Br Br
Br
Br +
Br
Br O
N
Br
Br
Br
OCH3
+
Br
Br
Br
OCH 3 O
Br
Br
Cl
Br
+
Br
Br
Br
Cl P
Br
Br
Cl
Br 1
Cl 8
7
HCl
O O2 H g/ )H BH 4 Br2 O a c2 A ii) N ( i)
i) B 2H 6 ii) CH 3COOH O
C
l
45.
O 6
2
O
O
i) B 2H 6 ii) H 2O 2 /OH – +
H 2O/H /Hg
ICl
H
Cl
78
Br
Cl
Cl
I I
Cl 5
4
O
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3 2+
H
Alkene & Alkyne 46. Terminal alkyne have acidic hydrogen so give white ppt with Tollen’s rea gent & red ppt with Cu 2 Cl 2 /NH 4 OH but non-terminal alkyne do not give such reactions. Tollen's reagent
R–C C Ag white ppt
R–C CH Cu2 Cl 2 / NH 4OH
R–C C Cu Red ppt
Tollen's reagent
No ppt
R–C C–R Cu 2Cl 2 /NH 4OH
No ppt
47. 48. Rate of electrophilic addition reaction depends on the stability of carboca tion formed after protonation while stability of substrate depends on electronic delocalization of bond. 49. Rate of electrophilic addition reaction depends on stability of carbocation. Carbocation formed by 1,3 -Butadiene is more stable than carbocation formed by But-1-ene so is the order. Br
50.
Br
HBr
+
+
Br
51.
+ Br
N
(B) Br
O 53. (A) CH –C–CH 3 3
Br
Br
HBr
52. (A)
Br
+
O
+
Br
Br
(C) O
(B)
Br O (D)
N
O
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79
Alkene & Alkyne O
(C)
(D)
O
OH
OH + H–C
H
..OH 54. Ph–CH–C CH
H
+
..
H 2O
Ph–CH–C CH
Ph–CH=C=CH –H+ O–H
O
Ph–CH=C=CH
Ph–CH=CH–C–H
55. (A)
HO
O
(B) OH
(C)
O
(D)
Ph Ph
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Alkene & Alkyne
Answers 02 Objective Approach
01.
(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)
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81
Alkene & Alkyne 91.
(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)
137. (A,B,C,D) 138. (A,C,D)
136.(A,B,C)
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)
149. (C,D)
150. (A,B)
147. (A,C)
148.(B,C)
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)
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Alkene & Alkyne
Answers 03 World of Competitions
01.
06.
(C)
(B)
02.
07.
(C)
(A)
03.
08.
(C)
(A)
04.
(D)
05.
O
O
OH
Q H
R
09.
(D)
10.
(A)
11.
(A)
12.
(B)
13.
P (C)
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)
14.
(A)
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