Chapter Twenty Two PDF

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Chapter Twenty Two Topic: Enols & Enolates Section: 22.1 Difficulty Level: Easy 1. Which one of the following compounds is most acidic? A) ethyl acetoacetate B) 2-butanone C) ethyl pentanoate D) 1-butanol E) 3-pentanone Ans: A Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 2....

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Chapter Twenty Two Topic: Enols & Enolates Section: 22.1 Difficulty Level: Easy 1. A) B) C) D) E)

Which one of the following compounds is most acidic? ethyl acetoacetate 2-butanone ethyl pentanoate 1-butanol 3-pentanone Ans: A

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 2. Which are the most acidic α- hydrogens in the following compounds? O

O

O

O

O

O

O

CH3CH2CH CH3CH2CCH2CCH2CH3 CH3CH2CCH2COCH2CH3 CH3CH2COCH2CH3 CH3CH2CCH2CH3

A) B) C) D) E)

I

I II III IV V Ans: B

II

III

IV

V

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 3. Which is the most acidic hydrogen in the following compound? V

O

I

H

H

CN

H

H

IV

H H

A) B) C) D) E)

II

H

III

I II III IV V Ans: A

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Hard 4. Which is the most acidic hydrogen in the following compound? O

O

O

H

O O

H

H H

A) B) C) D) E)

IV

H

I II III IV all of these Ans: C

H

III

II

H

I

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 5. Which one of the following is the most acidic compound? O

O

O

O

O

O

O

O

I

A) B) C) D) E)

III

II

V

IV O

I II III IV V Ans: D

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Easy 6. Which of the following is(are) a keto-enol tautomeric pair(s)? O CH3CH

O

CH

CH3CH

I

O

O CH3C

CH3CCH2

CH2

III A) B) C) D) E)

I II III I & II I & III Ans: B

CH

OH CH3C

O CH2

CH3CCH3 II

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 7. Which of the following is (are) a keto-enol tautomeric pair(s)? OH

O

O

III

II

I

OH

O

O

OH

IV

A) B) C) D) E)

O

O

OH

V

I II III IV V Ans: D

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 8. Which one of the following compounds would favor the enol tautomer over the ketone tautomer? O

O

I

O

O

H

II

O

III

O

O

IV

A) B) C) D) E)

I II III IV V Ans: A

V O

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Hard 9. Explain why the following equilibrium favors the enol tautomer. O

O

O

OH

Ans: The enol tautomer is stabilized by the conjugated π system and the intramolecular hydrogen bonding between the OH and the carbonyl group. Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 10. Explain why the following equilibrium favors the enol tautomer. O

OH

Ans: The enol tautomer is aromatic,with aromatic stability. The ketone tautomer is not aromatic. Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 11. Provide the structure of the enol when 3,3,6-trimethyl-4-heptanone is treated with acid. Ans:

OH

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 12. Provide the structure of the enolate when acetophenone is treated with strong base. Ans:

O

O

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 13. Which of the following base will completely convert 1,4-cyclohexanedione into an enolate? A) sodium hydroxide B) sodium ethoxide C) LDA D) sodium hydride E) both C & D Ans: E Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 14. Which one of the following compounds would undergo racemization at the α-stereocenter in presence of a base? O

O

O

H

A) B) C) D) E)

I

I II III IV none of these Ans: B

II

III

IV

O

Topic: Enols & Enolates Section: 22.1 Difficulty Level: Medium 15. Which of the following compound(s) would undergo racemization in presence of a base? O

O

O

II

I

I II III IV II & III Ans: B

H

H

H

A) B) C) D) E)

O CH3

IV

III

Topic: α-halogenation Section: 22.2 Difficulty Level: Easy 16. Predict the major product for the following reaction. O

H3O+ Cl2 O

O

O

O

O

Cl Cl

Cl

Cl

Cl Cl

Cl

A) B) C) D) E)

I

I II III IV V Ans: A

II

III

IV

V

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 17. Predict the major product for the following reaction. H3O+

PCC

OH

Br2

CH2Cl2 O

HO

O

Br

H

H

H

Br

II

I

III

O

O

H

Br

A) B) C) D) E)

Br

V

IV

I II III IV V Ans: C

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 18. Provide The reagents necessary to carry out the following conversion. H

OH

Ans:

1. PCC/CH2Cl2 2. H3O+/Br2 3. NaOCH2CH3

O

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 19. Provide The reagents necessary to carry out the following conversion. OH

O CN

Ans:

1. PCC/CH2Cl2 2. H3O+/Br2 3. NaCN

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 20. Predict the major product for the following reaction. O

H3O+

pyridine

Br2 O

O

O

+

II

I

O

OH

Br O

+

III

A) B) C) D) E)

I II III IV none of these Ans: A

IV

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 21. Predict the major product for the following reaction and provide a curved arrow mechanism for the formation of the product. O

H3O+ Br2

Ans:

O

Br

O

H

O

H

OH

OH

Br

H

H

+ H3O+

+ H2O H O

O

H2O + H3O+

Br

Br

Br

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 22. Predict the major product for the following reaction. O

1. Br2/PBr3 OH

2. H2O O

O

A) B) C) D) E)

HO

OH

Br

II

I

O

I II III IV none of these Ans: B

Br

Br

III

Br

OH

IV

Br

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 23. Predict the major product for the following reaction. OH

K2Cr2O7/H2SO4/H2O 1. Br2/PBr3 2. H2O

O

H

Br

A) B) C) D) E)

I

I II III IV V Ans: C

Br

III

Br

Br

OH

Br

II

O

O

O Br

Br

IV

V

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 24. Provide the reagents necessary to carry out the following conversion. O CN OH Br

Ans:

1. H3O+/heat 2. Br2/PBr3 3. H2O

Topic: α-halogenation Section: 22.2 Difficulty Level: Easy 25. Which of the following ketones will give a positive iodoform test? A) B) C) D) E)

3-heptanone 3-hexanone cyclohexanone 2-pentanone 2-methyl-3-hexanone Ans: D

Topic: α-halogenation Section: 22.2 Difficulty Level: Easy 26 Predict the major product for the following reaction. O

1. NaOH/Br2 2. H3O+

Br

I II III IV V Ans: E

I

OH

BrO

OH

II

OH

Br

III

IV

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 27. Provide the reagents necessary to convert acetophenone to benzoic acid. A) B) C) D) E)

K2Cr2O7/H2SO4/H2O 1. NaOH/Br2 2. H3O+ 1. KMnO4/NaOH/H2O 1. Br2/PBr3 2. H2O both A & C Ans: B

O

Br

Br

A) B) C) D) E)

HO

O

O

V

Topic: α-halogenation Section: 22.2 Difficulty Level: Medium 28. Predict the major product for the following reaction. O

1. NaOH/I2 2. H3O+ O

O

O

I

I HO

I

I

II

O

HO

IV

A) B) C) D) E)

III

OH

I

V

I II III IV V Ans: B

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 29. Predict the major product for the following reaction sequence. OH

KMnO4/NaOH/H2O

1. NaOH/I2 +

2. H3O

Ans:

O

O

I

CH3OH H2SO4

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 30. Provide the reagents necessary to carry out the following conversion. O

O Br N H

Ans:

1. 2. 3. 4.

NaOH/I2 H3 O+ Br2/PBr3 CH3NH2

Topic: α-halogenation Section: 22.2 Difficulty Level: Hard 31. Provide the reactant that would yield m-chlorobenzoic acid using the haloform reaction. O

O

O

O

CCH3

CCH2CH3

COH

CH

III

IV

Cl

I

A) B) C) D) E)

I II III IV V Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

Cl

II

CH2Cl

Cl

Cl

V

32. Which one of the following compound does not undergo an aldol addition reaction in presence of aqueous sodium hydroxide? A) B) C) D) E)

butanal 2-methylbutanal 3-methylpentanal 2,2-dimethylbutanal none of these Ans: D

Topic: Αldol reactions Section: 22.3 Difficulty Level: Easy 33. Predict the major product for the following reaction. O

NaOH/H2O O

H

O

OH

H

O

OH

H

OH

II

I O

III

O

O

H

IV

A) B) C) D) E)

I II III IV V Ans: B

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

OH

V

34. Predict the major product for the following reaction. NaOH, H2O butanal + 2,2-dimethylpentanal OH H

I

OH

OH

O

H

H

II

O

III

O

IV

A) B) C) D) E)

I II III IV V Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

OH

V

O

OH

35. Predict the major product for the following reaction. O O

NaOH/H2O

H

+ O

H

OH

O

O

OH

H

H

H

III

II

I OH

O

O

OH

H

V

IV

A) B) C) D) E)

O

I II III IV V Ans: D

Topic: Αldol reactions Section: 22.3 Difficulty Level: Hard 36. Predict the product when cyclohexanone reacts with aqueous sodium hydroxide at 1000C. O

I

A) B) C) D) E)

O

O

O

I II III IV none of these Ans: D

II

O

III

IV

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium 37. Predict the product for the following reaction. O

NaOH/H2O H

O

Δ O

H

H

II

I O

O

O

H

III

A) B) C) D) E)

I II III IV none of these Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

IV

38. Predict the product for the following reaction. O

O

H

NaOH/H2O

+

Δ

O O

O

O

O O

II

I O

O

O

O

O

O

III O

A) B) C) D) E)

O

I II III IV none of these Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Hard

IV O

39. Which one of the following is not a possible product when a crossed aldol addition reaction is carried out with ethanal and butanal as reactants? OH

O

OH

OH

O

H H

H

II

I OH

O

III

O OH

H

A) B) C) D) E)

I II III IV V Ans: B

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

IV

O

H

V

40. Predict the product for the following reaction. O

O

H NaOH/H O 2

+

Δ

O

O

IV

I II III IV V Ans: B

Topic: Αldol reactions Section: 22.3 Difficulty Level: Hard

III

II

I

A) B) C) D) E)

O

O

O

V

41. Predict the major product for the following reaction. O O

O

NaOH/H2O H

+

Δ

H

O

OH

O

O

O

O OH

O

O

H

I

H

III

II

O

OH

O O

H

IV

A) B) C) D) E)

I II III IV V Ans: D

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

O

H

V

42. Provide the reactants that would give the following aldol condensation product. O

O

O

O H H

+

O

I O

+ II

O

O H H

+ III

A) B) C) D) E)

I II III IV none of these Ans: C

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

+ O

IV

43. Provide the reactants that would give the following aldol condensation product. O

H

O

O

O H H

+

+

O

I

II

O

O

O

H H

+

+

O

IV

III

A) B) C) D) E)

I II III IV none of these Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium 44. Provide the reactants that would give the following aldol condensation product. O O

H

O

Ans:

O

O H

+ H

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium 45. Provide the reactant(s) that would give the following aldol condensation product. O

O

O

H

O

O

O

H

I

III

II

O

O O

O

O

H

IV

A) B) C) D) E)

I II III IV V Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Hard

V O

O

46. Predict the major product for the following reaction. O

O

NaOH/H2O Δ

O O O O

I

A) B) C) D) E)

I II III IV none of these Ans: C

Topic: Αldol reactions Section: 22.3 Difficulty Level: Medium

II

III

IV

47. Provide the reactant(s) that would give the following aldol condensation product. O

H

O

O

O

O

H H

HO H

I

O

H

II

III

O

O

O

+

A) B) C) D) E)

I II III IV V Ans: A

Topic: Αldol reactions Section: 22.3 Difficulty Level: Hard

H

IV

H

H

O

H

V

48. Provide the reactant(s) that would give the following possible aldol condensation product. O

O

O

O

H

H

II

I OH

O

O

O

O O

O

+ III

A) B) C) D) E)

IV

I II III IV V Ans: A

V

Topic: Claisen Condensation Section: 22.4 Difficulty Level: Easy 49. Which one of the following is a major product in a Claisen condensation? A) B) C) D) E)

∝-keto ester β-keto ester β-hydroxy ester γ-hydroxyester β-diketone Ans: B

Topic: Claisen Condensation Section: 22.4 Difficulty Level: Medium 50. Explain why CH3ONa should not be used for Claisen condensation of ethylbutanoate. Ans: Use of CH3ONa will result in transesterification product.

Topic: Claisen Condensation Section: 22.4 Difficulty Level: Easy 51. Predict the major product for the following reaction. O

1. NaOCH2CH3 2. H3O+

O

O

O

OH

O

O

O

O

I

III

II O

O

O

O O

IV

A) B) C) D) E)

V

O

I II III IV V Ans: A

Topic: Claisen Condensation Section: 22.4 Difficulty Level: Medium 52. Predict the major product for the following reaction. O

O

1. NaOCH2CH3 2. H3O+

A...