ch17-ques-2013

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Chapter Seventeen

Topic: Classification of Dienes Section: 17.1

Difficulty Level: Easy

1. Which of the following compounds are isolated dienes?

I II III IV V A) I B) II C) III D) IV E) V Ans. B

2. Which of the following compounds are conjugated dienes?

I II III IV A) I B) II C) III D) IV E) II & IV Ans. E

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3. Which of the following compounds have conjugated double bonds?

I II III IV V

Ans. I & III

4. Which of the following compounds have isolated double bonds?

I II III IV V

Ans. II & IV

Difficulty Level: Medium

5. Classify the following compounds as having cumulated, conjugated or isolated double bonds? C O I II III IV O O V Ans. I. conjugated II. cumulated III. conjugated IV. conjugated V. isolated

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6. Which of the following compounds are cumulated dienes? A) 4-methyl-1,3-heptadiene B) 5-methyl-2,6-heptadiene C) 2-methyl-2,4-heptadiene D) 4-methyl-1,4-heptadiene E) 5-methyl-2,3-heptadiene Ans. E

7. Which of the following compounds are conjugated dienes? A) 4-methyl-1,3-heptadiene B) 5-methyl-2,6-heptadiene C) 2-methyl-2,4-heptadiene D) 4-methyl-1,4-heptadiene E) 5-methyl-2,3-heptadiene Ans. A & C

8. Which of the following compounds are isolated dienes? A) 4-methyl-1,3-heptadiene B) 5-methyl-2,6-heptadiene C) 2-methyl-2,4-heptadiene D) 4-methyl-1,4-heptadiene E) 5-methyl-2,3-heptadiene Ans. B & D

Topic: Nomenclature of Dienes Section: 17.1 & 8.3

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9. What is the IUPAC name for the following compound? Cl A) 1-chloro-1-methyl-2,5-cyclohexadiene B) 3-chloro-3-methyl-1,4-cyclohexadiene C) 6- chloro-6-methyl-1,4-cyclohexadiene D) 2- chloro-2-methyl-1,3-cyclohexadiene E) None of these Ans: B

10. What is the IUPAC name for the following compound?

A) (2E, 4Z)-2,4-hexadiene B) (2E, 4Z)-1,4-dimethyl-1,3-butadiene C) (2Z, 4Z)-1,4-dimethyl-1,3-butadiene D) (2Z, 4Z)-2,4-hexadiene E) None of these Ans: A

Difficulty Level: Hard

A) (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–heptatriene B) (2Z,4E,)–3,4,7–trimethyl-2,4,6–octatriene C) (2E,4Z,6E)–2,5,6,7–tetramethyl-3,5,7–heptatriene D) (2E,4Z)– 2,5,6–trimethyl-3,5,7–octatriene E) (2E,4E,)–2,5,6–trimethyl-2,4,6–octatriene Ans: E

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Ans: 1-isopropyl-4-methyl-1,3-cyclopentadiene Topic: Nomenclature of Dienes

Section: 17.1 & 8.3 Difficulty Level: Easy

13. Provide the structure for (E)-1,3-pentadiene. Ans:

14. Provide the structure for (Z)-2-methyl-2,4-hexadiene. Ans:

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15. Provide the structure for (1E,3Z)-1-methoxy-2-methyl-1,3-pentadiene. H3CO OCH3 H3CO H₃CO I II III V H3CO IV A) I B) II C) III D) IV E) V Ans: A

16. Provide the structure for (3S,4E)-3-t-butyl-4-methyl-1,4-hexadiene. Ans:

Topic: Stability of Dienes Section: 17.2

17. Which one of the following dienes is most stable? A) CH3CH=CHCH=CHCH3 B) CH3CH=CHCH2CH=CH2 C) CH2=CHCH2CH2CH=CH2 D) CH2=CHCH(CH3)CH=CH2 E) CH3CH=C=CHCH2CH3 Ans: A

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18. Which one of the following dienes is least stable? A) CH3CH=CHCH=CHCH3 B) CH3CH=CHCH2CH=CH2 C) CH2=CHCH2CH2CH=CH2 D) CH2=CHCH(CH3)CH=CH2 E) CH3CH=C=CHCH2CH3 Ans: E

19. Which one of the following dienes is least stable?

I II III _IV C A) I B) II C) III D) IV Ans: D

20. Which one of the following dienes is most stable?

I II III IV A) I B) II C) III D) IV Ans: C

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21. Rank the following dienes in increasing order of stability (least to most). I II III IV C A) I<IV<III<II B) III<II<I<IV C) IV<II<III<I D) II<IV<III<I E) I<III<II<IV Ans: C

22. Which one of the following dienes will have the least heat of hydrogenation?

I II III IV V C A) I B) II C) III D) IV E) V Ans: A

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23. Which one of the following dienes will have the highest heat of hydrogenation? I _II III IV V A) I B) II C) III D) IV E) V Ans: C

24. Rank the following dienes in order of decreasing heat of hydrogenation (most to least).

I II III

IV V

C

Ans: IV>V>II>III>I Topic: Stability of Dienes Section: 17.2

25. Rank the following dienes in order of decreasing heat of hydrogenation (most to least).

I II III IV

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Topic: Preparation of Dienes Section: 17.2

26. Predict the product for the following reaction.

Br

(CH₃)₃COK

Ans:

(CH₃)₃COK

Cl

Ans:

28. Provide the reagents necessary to carry out the following conversion.

Ans: 1. NBS,heat 2. (CH3)3COK Topic: Preparation of Dienes Section: 17.2

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29. Provide the reagents necessary to carry out the following conversion. OH

Ans: 1. H2SO4, heat 2. NBS,heat 3. (CH3)3COK Topic: Preparation of Dienes Section: 17.2

30. Provide the reagents necessary to carry out the following conversion.

Ans: Cl2 Cl (CH3)3COK NBS Br (CH3)3COK h! _heat

Topic: Molecular Orbitals Section: 17.3

31. Which one of the following represents the lowest energy π-bonding molecular orbital of 1,3-butadiene? I II III IV A) I B) II C) III D) IV Ans: C

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32. Which one of the following represents the highest energy π-antibonding molecular orbital of 1,3-butadiene? I II III IV A) I B) II C) III D) IV Ans: B

33. How many π-bonding molecular orbitals does 1, 3-pentadiene have? A) 1 B) 2 C) 3 D) 4 E) none Ans: B

34. How many electrons does the HOMO of 1, 3-pentadiene have in its excited state? A) 1 B) 2 C) 3 D) 4 E) none Ans: A

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35. How many electrons does the HOMO of 2, 4-hexadiene have in its ground state? A) 1 B) 2 C) 3 D) 4 E) 0 Ans: B

36. How many electrons does the LUMO of 2, 4-hexadiene have in its ground state? A) 1 B) 2 C) 3 D) 4 E) 0 Ans: E

37. Which one of the following represents the HOMO of 1,3, 5-hexatriene?

I II III IV V A) I B) II C) III D) IV E) V Ans: A

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38. Which one of the following represents the LUMO of 1,3, 5-hexatriene? I _II III IV V A) I B) II C) III D) IV E) V Ans: D

Topic: Electrophilic addition reactions of conjugated dienes Section: 17.4

39. Which major product(s) are formed for the following reaction?

HI I I I I I _II III IV I V A) I B) II C) III D) IV E) V Ans: A

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40. Which one of the following compounds is not a product of reaction between 1,3-butadiene and HBr? A) (S)-3-bromo-1-butene B) (R)-3-bromo-1-butene C) (E)-1-bromo-2-butene D) (Z)-1-bromo-2-butene E) (Z)-2-bromo-2-butene Ans: E

41. Predict the product(s) for the following reaction.

HCl Ans: Cl Cl + ₊ Cl Cl +

42. Predict the possible major products for the following reaction.

HBr Ans: Br Br Br Br + ₊ ₊

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43. Predict the possible products for the following reaction and provide a curved arrow mechanism for the formation of these products.

HBr Ans: Br Br + ₊ ₊ Br Br H Br Br Br Br Br H Br Br Br Br Br

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44. Provide the structure of the 1,4 addition product for the reaction of 1,3-hexadiene with Br2/CCl4?

Ans: Br

Br

45. Provide the structure of the 1,2 addition product for the following reaction.

Br2

CCl₄

Ans: Br

Br

Topic: Reaction Mechanisms and Control Section: 17.5

46. A thermodynamically-controlled reaction will yield : A) the most stable product.

B) the product whose formation requires the smallest free energy of activation. C) the product that can be formed in the fewest steps.

D) the product that is formed at the fastest rate. E) None of these.

Ans: A

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47. A reaction under kinetic control will yield : A) the most stable product.

B) the product that can be formed in the fewest steps.

C) the product whose formation requires the smallest free energy of activation. D) the product with the greatest potential energy.

E) None of these Ans: C

48. Predict the major product for the following reaction.

HCl 00C

Ans:

Cl

HCl 400C

Ans:

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50. Provide the structure for 1,2 addition product for the following reaction and explain why it is a major product rather than 1,4 addition product.

HBr 400C

Ans: Br

1,2-product is the major one because the double bond is trisubstituted and is more stable than the double bond in 1,4-product, which is disubstituted

51. Predict the major product for the following reaction and explain why it is major product.

HBr 400C

Ans:

Br

1,4-product is the major one because the double bond is tetrasubstituted and is more stable than the double bond in 1,2-product, which is trisubstituted Topic: Reaction Mechanisms and Control

Section: 17.5

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HCl 00C

Ans: Cl

Topic: Pericyclic Reaction Section: 17.6

53. What is the correct classification of the following pericyclic reaction?

heat A) electrophilic addition B) sigmatropic rearrangement C) cycloaddition D) electrocyclic reaction E) C & D Ans: B

54. What is the correct classification of the following pericyclic reaction?

A) electrophilic addition B) sigmatropic rearrangement C) cycloaddition D) electrocyclic reaction E) C & D Ans: D

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55. What is the correct classification of the following pericyclic reaction? + A) electrophilic addition B) sigmatropic rearrangement C) cycloaddition D) electrocyclic reaction E) C & D Ans: C

Topic: Diels-Alder Reaction Section: 17.6 & 17.7

56. Which statement is NOT true about the Diels-Alder reaction? A) It is a [4+2] cycloaddition reaction.

B) The diene must be in the s-cis conformation to react. C) Most Diels-Alder reactions are reversible.

D) It is a sigmatropic rearrangement.

E) Electron donating groups on the diene and electron withdrawing groups on the dieneophile favor product formation.

Ans: D

Topic: Diels-Alder Reaction Section: 17.6 & 17.7

57. The Diels Alder reaction is a concerted reaction, which means A) The product contains a cyclic ring

B) The diene must be in the s-cis conformation to react.

C) All changes in bonding (bond making and bond breaking) occur simultaneously. D) It is an endothermic reaction

E) Both exo and endo products are formed Ans: C

Topic: Diels-Alder Reaction Section: 17.7

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58. Which of the following dienes can undergo the Diels-Alder reaction? I II III IV A) I B) II C) III D) IV

E) All of the these Ans: II

59. Which of the following diene(s) can not undergo the Diels-Alder reaction?

I _II III IV A) I B) II C) III D) IV E) I & IV Ans: E

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60. Which one of the following dienophiles is least reactive in the Diels-Alder reaction? O H O OCH₃ O H3CO CN OCH₃ _NO 2 I II III IV V A) I B) II C) III D) IV E) V Ans: D

61. Which one of the following dienophiles is most reactive in the Diels-Alder reaction?

OCH₃ I III IV O O O II V A) I B) II C) III D) IV E) V Ans: C

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62. Predict the product for the following Diels-Alder reaction. O + ! O _O CCH3 O CCH3 O I II III IV A) I B) II C) III D) IV E) none of these Ans: B

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63. Predict the product for the following Diels-Alder reaction. COCH3 O ! + OCH3 O OCH3 O COCH3 O CCH3 O I II _III IV A) I B) II C) III D) IV E) None of these Ans: B

64. Predict the product for the following Diels-Alder reaction.

! C C C + C N N Ans: CN CN

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65. Predict the major product for the following Diels-Alder reaction. C OH OH C O O + ! Ans: COH COH O O + enantiomer Topic: Diels-Alder Reaction

Section: 17.7

66. Predict the major product for the following Diels-Alder reaction.

+

!

Ans:

67. Predict the major product for the following Diels-Alder reaction. Cl OCCH3 O ! + Ans: OCCH3 Cl O

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68. Predict the product for the following Diels-Alder reaction.

+ ! O O Excess Ans: O O Topic: Diels-Alder Reaction Section: 17.7

69. Predict the major product for the following Diels-Alder reaction.

O O O + ! Ans: O O O

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70. Compound A is one of the intermediate products in the synthesis of the corticoid hormone cortisone. Provide the structure of compound A.

H3CH2CO O O ! + Compound A Ans: O O H3CH2CO

71. Predict the major product for the following Diels-Alder reaction. H3CO O2N H CH2OCH3 H ! + Ans: H₃CO CH₂OCH₃ NO2

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72. Predict the major product for the following intramolecular Diels-Alder reaction and provide a curved arrow mechanism for the formation of the product.

H3CO OCH3 O ! Ans: OCH3 OCH3 O H₃CO OCH₃ O Mechanism

73. The following Diels-Alder reaction product is an intermediate in the synthesis of Estrone. Provide the structure of the product.

H3CO O O + Δ Ans: O O H3CO

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74. The following Diels-Alder reaction product is an intermediate in the synthesis of Cholesterol. Provide the structure of the product.

O O H₃CO CH3 ! + Ans: OCH3 O O CH3

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75. What diene and dienophile would react to give the following Diels-Alder product? COH O COH O COH COH O O COH COH O O COH COH O O I _II III COH COH O O IV + + + ₊ A) I B) II C) III D) IV Ans: B

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76. What diene and dienophile would react to give the following Diels-Alder product? I _II _III IV V + + + + + A) I B) II C) III D) IV E) V Ans: B

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77. What diene and dienophile would react to give the following Diels-Alder product? CCH3 O I III IV V + + + + II + CCH3 O CCH3 O CCH3 O CCH3 O CCH3 O A) I B) II C) III D) IV E) V Ans: B

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78. What diene and dienophile would react to give the following Diels-Alder product? CN CN I _II CN CN III CH2CH3 V IV CN CN + ₊ + + + CN NC CN CN A) I B) II C) III D) IV E) V Ans: D

79. What diene and dienophile would react to give the following Diels-Alder product?

Ans:

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O O Ans: O O +

O COCH₃ H O Ans: + O COCH3 O

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82. What diene and dienophile would react to give the following Diels-Alder product? O O Ans: + O O + + O O OR

O O O Ans: O O O +

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O2N

Ans: NO2

+

85. The following product is formed by an intramolecular Diels-Alder reaction. Provide the structure of the starting compound.

O

Ans:

O Topic: Diels-Alder Reaction

Section: 17.7

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86. What diene and dienophile would react to give the following Diels-Alder product? O

Ans: O

+

O

CN

Ans:

CN

O ₊

Topic: Electrocyclic Reactions Section: 17.9

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88. Which of the following best describes the stereochemistry of ring closure and the product for the following reaction?

Δ A) disrotatory, cis-3,4-diethylcyclobutene B) conrotatory, cis-3,4-diethylcyclobutene C) disrotatory, trans-3,4-diethylcyclobutene D) conrotatory, trans-3,4-diethylcyclobutene Ans: D

hν

A) disrotatory, cis-3,4-diethylcyclobutene B) conrotatory, cis-3,4-diethylcyclobutene C) disrotatory, trans-3,4-diethylcyclobutene D) conrotatory, trans -3,4-diethylcyclobutene

Ans: A

hν (3E,5Z,7E)-3,5,7-decatriene

A) disrotatory, cis-5,6-diethyl-1,3-cyclohexadiene B) conrotatory, cis-5,6-diethyl-1,3-cyclohexadiene C) disrotatory, trans-5,6-diethyl-1,3-cyclohexadiene D) conrotatory, trans -5,6-diethyl-1,3-cyclohexadiene

Ans: D

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Δ (3E,5Z,7E)-3,5,7-decatriene

A) disrotatory, cis-5,6-diethyl-1,3-cyclohexadiene B) conrotatory, cis-5,6-diethyl-1,3-cyclohexadiene C) disrotatory, trans-5,6-diethyl-1,3-cyclohexadiene D) conrotatory, trans -5,6-diethyl-1,3-cyclohexadiene

Ans: A

92. Predict the product for the following electrocyclic reaction.

h!

Ans:

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h!

Ans:

!

Ans:

+ enantiomer

Topic: Sigmatropic Rearrangement Section: 17.10

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95. Predict the product for the following Claisen rearrangement. O ! OH OH OH I II III OH IV A) I B) II C) III D) IV Ans: D

96. Predict the product for the following Cope rearrangement.

! I II III IV A) I B) II C) III D) IV Ans: C

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Δ

OH

Ans: O

98. Predict the product for the following Claisen rearrangement and provide the curved arrow mechanism for formation of the product.

! O Ans: _OH O O OH tautomerization

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99. Predict the product for the following Cope rearrangement and provide the curved arrow mechanism for formation of the product.

!

Ans:

Mechanism

100. Predict the product for the following reaction and provide the curved arrow mechanism for formation of the product.

O D ! Ans: O _D Mechanism O D

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101. Provide the structures of A, B and C for the following reaction sequence. OH 1. NaOH 2. Br A ! B 1. NaOH 2. CH3CH2Br C Ans: O A OH B O C

Topic: UV-Vis Spectroscopy Section: 17.11

102. Absorption of UV-visible radiation by a molecule results in___________ transitions. A) electronic B) nuclear C) rotational D) vibrational E) None of these Ans: A

103. Which is the most energetically favorable UV transition for 1,3-butadiene?. A) n → σ* B) n → π* C) π2 → π3* D) σ → σ* E) π1 → π4* Ans: C

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104. Which of the following compound(s) have the longest λmax? A) (E) 2-pentene B) (Z) 2-pentene C) 1−pentene D) 1,3−hexadiene E) 1,3,5−hexatriene Ans: E

105. Which of the following compound(s) have the longest λmax?

I II III IV V A) I B) II C) III D) IV E) V Ans: B

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106. Which of the following compound(s) have the longest λmax? CH=CHCH=CH₂ CH=CHCH=CH₂ _CH=CHCH=CH₂ CH=CHCH=CH2 CH=CHCH=CH2 I _II III IV V A) I B) II C) III D) IV E) V Ans: A