ch17-ques-2013

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Chapter Seventeen

Topic: Classification of DienesSection: 17.1

Difficulty Level: Easy

1. Which of the following compounds are isolated dienes?

I II III

IV V A) I

B) IIC) III

D) IVE) V

Ans. B

Topic: Classification of Dienes

Section: 17.1Difficulty Level: Easy

2. Which of the following compounds are conjugated dienes?

I II III IV A) I

B) IIC) III

D) IVE) II & IV

Ans. E



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

III III IV V

Ans. I & III



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

I II III IVV

Ans. II & IV


Difficulty Level: Medium

5. Classify the following compounds as having cumulated, conjugated or isolated double bonds?

C O

I IIIII IV

O

O

V

Ans. I. conjugated

II. cumulated

III. conjugatedIV. conjugated

V. isolated

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6. Which of the following compounds are cumulated dienes?

A) 4-methyl-1,3-heptadieneB) 5-methyl-2,6-heptadiene

C) 2-methyl-2,4-heptadieneD) 4-methyl-1,4-heptadiene

E) 5-methyl-2,3-heptadieneAns. E

Topic: Classification of Dienes

Section: 17.1Difficulty Level: Medium

7. Which of the following compounds are conjugated dienes?

A) 4-methyl-1,3-heptadiene

B) 5-methyl-2,6-heptadieneC) 2-methyl-2,4-heptadiene

D) 4-methyl-1,4-heptadieneE) 5-methyl-2,3-heptadiene

Ans. A & C



8. Which of the following compounds are isolated dienes?

A) 4-methyl-1,3-heptadieneB) 5-methyl-2,6-heptadiene

C) 2-methyl-2,4-heptadieneD) 4-methyl-1,4-heptadiene

E) 5-methyl-2,3-heptadieneAns. B & D

Topic: Nomenclature of Dienes

Section: 17.1 & 8.3Difficulty Level: Medium

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9. What is the IUPAC name for the following compound?Cl

A) 1-chloro-1-methyl-2,5-cyclohexadieneB) 3-chloro-3-methyl-1,4-cyclohexadiene

C) 6- chloro-6-methyl-1,4-cyclohexadieneD) 2- chloro-2-methyl-1,3-cyclohexadiene

E) None of theseAns: B



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

A) (2E, 4Z)-2,4-hexadieneB) (2E, 4Z)-1,4-dimethyl-1,3-butadiene

C) (2Z, 4Z)-1,4-dimethyl-1,3-butadieneD) (2Z, 4Z)-2,4-hexadiene

E) None of theseAns: A


Section: 17.1 & 8.3Difficulty Level: Hard


A) (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–heptatrieneB) (2Z,4E,)–3,4,7–trimethyl-2,4,6–octatriene

C) (2E,4Z,6E)–2,5,6,7–tetramethyl-3,5,7–heptatrieneD) (2E,4Z)– 2,5,6–trimethyl-3,5,7–octatriene

E) (2E,4E,)–2,5,6–trimethyl-2,4,6–octatrieneAns: E

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Topic: Nomenclature of DienesSection: 17.1 & 8.3



Ans: 1-isopropyl-4-methyl-1,3-cyclopentadiene


Section: 17.1 & 8.3Difficulty Level: Easy

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

Ans:


Section: 17.1 & 8.3Difficulty Level: Easy

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

Ans:

Topic: Nomenclature of DienesSection: 17.1 & 8.3


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15. Provide the structure for (1E,3Z)-1-methoxy-2-methyl-1,3-pentadiene.

H3CO

OCH3

H3CO

H3CO

III III

V

H3CO

IV A) IB) II

C) IIID) IV

E) VAns: A



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

Ans:

Topic: Stability of DienesSection: 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) CH

2=CHCH(CH

3)CH=CH

2

E) CH3CH=C=CHCH2CH3 Ans: A

Topic: Stability of Dienes


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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 IIIIV

C

A) I

B) IIC) III

D) IVAns: D



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

I II IIIIV

A) I

B) IIC) III

D) IVAns: C



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21. Rank the following dienes in increasing order of stability (least to most).

I

II IIIIV

C

A) I<IV<III<II

B) III<II<I<IVC) IV<II<III<I

D) II<IV<III<IE) 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) IB) II

C) IIID) IV

E) VAns: A



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23. Which one of the following dienes will have the highest heat of hydrogenation?

I II

III IVV

A) IB) II

C) IIID) IV

E) VAns: 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



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

I II IIIIV

Ans: IV>II>I>III

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Topic: Preparation of DienesSection: 17.2


26. Predict the product for the following reaction.

Br

(CH3)3COK

Ans:

Topic: Preparation of DienesSection: 17.2



(CH3)3COK

Cl

Ans:

Topic: Preparation of Dienes


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

Ans: 1. NBS,heat

2. (CH3)3COK



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

Ans: 1.

H2SO4, heat2. NBS,heat3. (CH3)3COK


Section: 17.2Difficulty Level: Hard

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


31. Which one of the following represents the lowest energy π-bonding molecular orbital of

1,3-butadiene?

I II III IV A) IB) II

C) IIID) IV

Ans: C

Topic: Molecular OrbitalsSection: 17.3


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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) IIC) III

D) IVAns: B


Section: 17.3


33. How many π-bonding molecular orbitals does 1, 3-pentadiene have?

A) 1

B) 2C) 3

D) 4E) none

Ans: B

Topic: Molecular OrbitalsSection: 17.3Difficulty Level: Medium

34. How many electrons does the HOMO of 1, 3-pentadiene have in its excited state?

A) 1

B) 2C) 3

D) 4E) none

Ans: A



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35. How many electrons does the HOMO of 2, 4-hexadiene have in its ground state?

A) 1B) 2

C) 3

D) 4E) 0Ans: B



36. How many electrons does the LUMO of 2, 4-hexadiene have in its ground state?

A) 1

B) 2C) 3

D) 4E) 0

Ans: E


Difficulty Level: Hard

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

I II III

IV V A) IB) II

C) III

D) IVE) 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) IIC) III

D) IVE) V

Ans: D

Topic: Electrophilic addition reactions of conjugated dienesSection: 17.4Difficulty Level: Medium

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

HI

I

I

I

I

I IIIII IV

I

V

A) IB) II

C) IIID) IV

E) VAns: A

Topic: Electrophilic addition reactions of conjugated dienes


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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-buteneB) (R)-3-bromo-1-butene

C) (E)-1-bromo-2-butene

D) (Z)-1-bromo-2-buteneE) (Z)-2-bromo-2-buteneAns: 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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Topic: Electrophilic addition reactions of conjugated dienesSection: 17.4


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

Br 2/CCl4?Ans: Br

Br



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

Br 2

CCl4

Ans: Br

Br

Topic: Reaction Mechanisms and Control


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

Topic: Reaction Mechanisms and ControlSection: 17.5


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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 theseAns: C



48. Predict the major product for the following reaction.

HCl

00C

Ans:

Cl




HCl

400C

Ans:

Cl

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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 ismore stable than the double bond in 1,2-product, which is trisubstituted



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HCl

00C

Ans: Cl

Topic: Pericyclic Reaction


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

heat

A) electrophilic addition

B) sigmatropic rearrangementC) cycloaddition

D) electrocyclic reactionE) C & D

Ans: B

Topic: Pericyclic ReactionSection: 17.6



A) electrophilic additionB) sigmatropic rearrangement

C) cycloadditionD) electrocyclic reaction

E) C & DAns: D

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Topic: Pericyclic ReactionSection: 17.6



+

A) electrophilic addition

B) sigmatropic rearrangementC) cycloadditionD) electrocyclic reaction

E) C & DAns: C

Topic: Diels-Alder ReactionSection: 17.6 & 17.7Difficulty Level: Easy

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 thedieneophile favor product formation.

Ans: D

Topic: Diels-Alder ReactionSection: 17.6 & 17.7


57. The Diels Alder reaction is a concerted reaction, which meansA) 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 reactionE) Both exo and endo products are formed

Ans: C

Topic: Diels-Alder ReactionSection: 17.7


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58. Which of the following dienes can undergo the Diels-Alder reaction?

I

IIIII

IV

A) I

B) IIC) III

D) IVE) All of the these

Ans: II



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

I IIIII

IV

A) I

B) IIC) III

D) IVE) 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

H3

CO

CN OCH3 NO2

I IIIII

IVV

A) IB) II

C) IIID) IV

E) VAns: D

Topic: Diels-Alder Reaction


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

OCH3

I

III

IV

O

O

OII

V

A) IB) II

C) IIID) IV

E) VAns: C

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62. Predict the product for the following Diels-Alder reaction.O

+

!

O OCCH3

O

CCH3

O

III

III IV A) IB) II

C) IIID) IV

E) none of theseAns: B


Section: 17.7


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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) IB) II

C) IIID) IV

E) None of theseAns: B




!

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




+

!

Ans:




Cl OCCH3

O

!

+

Ans:

OCCH3

Cl

O

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+

!

O

O

Excess

Ans: O

O




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




H3CO

O2N

HCH2OCH3

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

OMechanism



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

III

III

COH

COH

O

O

IV

++

++

A) IB) II

C) IIID) IV

Ans: B



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I II III

IV V

+

+

+ +

+

A) IB) IIC) III

D) IVE) V

Ans: B



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CCH3

O

I

III

IV V

+

+

+

+

II

+

CCH3

O

CCH3

O

CCH3

O

CCH3

O

CCH3

O

A) I

B) IIC) III

D) IVE) V

Ans: B



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CN

CN

III

CN

CN

III

CH2CH3

VIV

CN

CN

+ ++

++

CN

NC

CN

CN

A) IB) II

C) IIID) IV

E) VAns: D




Ans:

+

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

O

Ans:

O

O

+




COCH3

H

O Ans:

+O

COCH3

O


Section: 17.7


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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



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Ans: O

+




CN

Ans:

CN

O +

Topic: Electrocyclic ReactionsSection: 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-diethylcyclobuteneC) disrotatory, trans-3,4-diethylcyclobutene

D) conrotatory, trans-3,4-diethylcyclobuteneAns: D

Topic: Electrocyclic Reactions


89. Which of the following best describes the stereochemistry of ring closure and the

product for the following reaction?

hν

A) disrotatory, cis-3,4-diethylcyclobutene

B) conrotatory, cis-3,4-diethylcyclobuteneC) disrotatory, trans-3,4-diethylcyclobutene

D) conrotatory, trans -3,4-diethylcyclobuteneAns: A



90. Which of the following best describes the stereochemistry of ring closure and the

product for the following reaction?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-cyclohexadieneC) disrotatory, trans-5,6-diethyl-1,3-cyclohexadiene

D) conrotatory, trans -5,6-diethyl-1,3-cyclohexadieneAns: D



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

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-cyclohexadieneC) disrotatory, trans-5,6-diethyl-1,3-cyclohexadiene

D) conrotatory, trans -5,6-diethyl-1,3-cyclohexadieneAns: A



92. Predict the product for the following electrocyclic reaction.

h!

Ans:



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Δ

OH

Ans: O

Topic: Sigmatropic RearrangementSection: 17.10


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

!

O

Ans: OH

OO OH

tautomerization



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

!

Ans: Mechanism

Topic: Sigmatropic RearrangementSection: 17.10Difficulty Level: Medium

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

for formation of the product.

O D

!

Ans:

OD

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!

B1. NaOH

2. CH3CH2Br

C

Ans:

O

A

OH

B

O

C

Topic: UV-Vis SpectroscopySection: 17.11


102. Absorption of UV-visible radiation by a molecule results in___________ transitions.

A) electronicB) nuclear

C) rotationalD) vibrational

E) None of these

Ans: A

Topic: UV-Vis Spectroscopy


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-penteneB) (Z) 2-pentene

C) 1− pentene

D) 1,3−hexadieneE) 1,3,5−hexatriene

Ans: E

Topic: UV-Vis Spectroscopy



I IIIII

IV V

A) I

B) IIC) III

D) IVE) V

Ans: B



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CH=CHCH=CH2 CH=CHCH=CH2 CH=CHCH=CH2 CH=CHCH=CH2 CH=CHCH=CH2

I II III IV V

A) IB) II

C) IIID) IV

E) VAns: A

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