Organic Chemistry Chapter 6 PDF

Preview

Summary

Lecture Notes...

Description

Chapter 6 Chirality

Multiple Choice 1. Which compounds contain stereocenters? (Sec. 6.3) I) 1-chloropentane II) 2-chloropentane III) 3-chloropentane IV) 1,2-dichloropentane a) b) c) d)

I, II III, IV I, III II, IV

2. Which compounds contain stereocenters? (Sec. 6.3) I) 2-methylpentane II) chlorocyclohexane III) 3-methyl-2-butanol IV) 2-hydroxypropanoic acid a) b) c) d)

I, II III, IV I, III II, IV

3. Which compounds contain stereocenters? (Sec. 6.3)

OH OH I.

HO

OH

O III.

CH3CCH2CH3

CH CH2

II.

IV.

H3C

CHCHCH3 H3C

a) b) c) d)

I, II III, IV I, III II, IV

61

OH

Chapter 6 Chirality

4. Which compounds have multiple stereocenters? (Sec. 6.3, 6.5)

HO CH3 I. CH3CHCHCH3

HO OH O II. CH3CHCH COH O

Cl OH III. CH3CHCHCH3

CH2COH

IV.

HO C COH CH2O COH O a) b) c) d)

I, II III, IV II, III I, III

5. How many stereoisomers are possible for 1,2-dichlorocyclopentane? (Sec. 6.3) a) b) c) d)

1 2 3 4

6. How many stereoisomers are possible for 2,3-butanediol? (Sec. 6.3) a) b) c) d)

1 2 3 4

7. How many stereoisomers are possible for the following structure? (Sec. 6.2-6.3)

OH

O

CH3CHCHCOH NH2 a) b) c) d)

1 2 3 4

62

Chapter 6 Chirality

8. Which structures are chiral? (Sec. 6.3)

H Cl

H

Cl

H

H2C C

H2C C

C C

CHCH2CH3

CH2CH2CH3

CH2CH2CH3 I.

Cl

II.

III. H

H H2C

H2C C

C

CH2CH2CH2

CH2CHCH3

Cl

Cl IV.

a) b) c) d)

V.

I, II, V I, II II, II, IV III, IV

9. Which pair of structures are enantiomers? (Sec. 6.3)

CH3 H HOC

I.

OH

H O HO H3C

O Cl Br

II.

Br

H3C CH3 CH2CH3 H3CH2C H

III.

a) b) c) d)

I

COH

OH

Cl

CH3 CH3

I

H

OH

I, II II, III I, III I, II, III

63

Chapter 6 Chirality

10. What is the relationship between these two structures? (Sec. 6.3, 6.5)

NH2 H

CH3

H3C

NH2

H

NH2

H2N

CH3

CH3 a) b) c) d)

H

H

Identical structures Enantiomers Diastereomers Constitutional isomers

11. What is the relationship between these two structures? (Sec. 6.3, 6.5)

a) b) c) d)

H

H

H

Cl

Br

Cl

Br

H

identical structures enantiomers diastereomers constitutional isomers

64

Chapter 6 Chirality

12. Which are meso compounds? (Sec. 6.5) O CH2OCH3

CH

H

OH

H

OH

H

OH

H

OH

CH2OH

CH O

I.

II. CH2OH

a) b) c) d)

CH2OH

H

OCH3

H3CO

H

OCH3

H

CH2OH

III.

IV.

13. How many stereoisomers are possible for Prilosec? (Sec. 6.7)

H N

N

CH3 O a) b) c) d)

OCH3

CH2OH

I, II I, III II, III III, IV

O

H

.HCl

CH3

OH

4 8 16 32

65

Chapter 6 Chirality

14. How many pairs of enantiomers are possible for cortisone acetate? (Sec. 6.7)

OH O CH3

O

O

CH3

O

O a) b) c) d)

32 64 128 256

15. Which forms of lactic acid are R forms? (Sec. 6.4)

O

O

COH HO H3C

H

I.

a) b) c) d)

CH3 H HOC

COH

OH

O II.

CH3

H CH3 HO

HO H

COH O

III.

IV.

I, II III, IV I, III II, IV

16. What is the R,S configuration for the following structure of isocitric acid? (Sec. 6.4)

O

O

COH H C #1 C HO COH H O

HOCCH2

a) b) c) d)

2-R, 3-R 2-R, 3-S 2-S, 3-R 2-S, 3-S

66

Chapter 6 Chirality

17. The specific rotation of dextrorotatory tartaric acid is +12.7 degrees. A mixture of dextrorotatory and levorotatory tartaric acid has a specific rotation of +6.35 degrees. What is the optical purity of the mixture? (Sec. 6.9) a) b) c) d)

25% 33 1/3% 50% 75%

18. Rank the following substituents in order of increasing priority. (Sec. 6.4)

a) b) c) d)

OH

Cl

CH3

I.

II.

III.

H IV

I, III, II, IV II, I, III, IV III, I, II, IV IV, III, I, II

19. Rank the following substituents in order of increasing priority. (Sec. 6.4)

H C C H

OCH3

II.

III.

C O H

I. a) b) c) d)

OH H

IV.

III, II, IV, I I, IV, II, III IV, I, III, II I, II, III, IV

20. Rank the following substituents in order of decreasing priority (highest first). (Sec. 6.4)

OCH3 I. a) b) c) d)

O

O

COH

CH

OCH2CH3

II.

III.

IV.

II, III, IV, I III, IV, I, II IV, III, II, I IV, I, II, III

67

Chapter 6 Chirality

21. Rank the following substituents in order of increasing priority. (Sec. 6.4)

H C C H

H I.

CH3

CH3

C CH3

C H

CH3

CH3

II.

III.

H C C H

H3C IV.

a) III, II, IV, I b) IV, I, II, III c) I, III, II, IV d) IV, II, I, III 22. Which structures represent R-3-methylhexane? (Sec. 6.4)

H3C

H

H

I. a) b) c) d)

CH3

CH3

H

II.

H

III.

CH3

IV.

II, III I, III I, II III, IV

23. Which structure is correctly named 3R,4S-3,4-dimethylhexane (Sec. 6.4)

H3C

H

H

H3C H

H CH3

I. a) b) c) d)

CH3

H3C H H3C

II.

H III.

II I, III III III, IV

24. Which statement about enantiomers is false? (Sec. 6.8) a) b) c) d)

enantiomers have the same boiling and melting points. enantiomers have the same chemical properties. enantiomers have the same atom connectivity. enantiomers have the same three dimensional orientation.

68

H CH3

H3C

H IV.

Chapter 6 Chirality

25. Which statements about stereoisomers are true? (Sec. 6.8, 6.9) I) enantiomers and diastereomers have the same physical properties. II) 50/50 mixtures of R and S enantiomers are called racemic mixtures. III) meso isomers rotate the plane of plane polarized light. IV) dextrorotatory compounds rotate plane polarized light to the right. a) b) c) d)

I, II II, III II, IV III, IV

Fill in the Blank 1. The following structure contains ___________ stereocenters. (Sec. 6.7)

OH OH O

Nadolol (beta-blocker)

OH N

2. The following structure contains __________ stereocenters. (Sec. 6.7)

CH3 N

morphine O

OH

3. The priority order for the following groups are (highest = 1),

CH3 C

CH3 CH3

H

CH3 C C H

CH3 C C H

C H CH3

(Sec. 6.4)

69

Chapter 6 Chirality

4. The priority order for the following groups is (highest = 1),

Br

Cl C

Cl CH3

C H CH3

Cl

OH

C OH CH3

C H CH3

(Sec. 6.4) 5. The following structure is the _____________ configuration. (Sec. 6.4)

OH

OH 6. The following structure is the _____________ configuration. (Sec. 6.4)

NH2 OH Br 7. The structure of the R,R enantiomer of 2,3-butanediol is,

(Sec. 6.4) 8. The structure of the S,R enantiomer of 3-bromo-4-chlorohexane is,

(Sec. 6.4)

70

Chapter 6 Chirality

9. The following structures are __________________ (what type of stereoisomer). (Sec. 6.3, 6.5)

OH

NH2

OH

NH2

10. The following structures are ________________ (what type of stereoisomer). (Sec. 6.3, 6.5)

True-False 1. The following structures are enantiomers. (Sec. 6.3)

Cl

H Cl HO

CH3

H HO

CH3

2. The following structures are diastereomers. (Sec. 6.5)

Br

Cl

Cl

Br

3. The name of the following structure is 2S,3S-2,3-dibromobutane. (Sec. 6.4)

Br

Br 4. The diastereomer of 2R,3R-dichlorobutane is achiral. (Sec. 6.5) 5. The following groups are listed in decreasing order of priority. (Sec. 6.4)

O

O OH >

OCH3 >

> CH3

OH

71

Chapter 6 Chirality

6. The following groups are listed in decreasing order of priority. (Sec. 6.4)

OH >

NH2

>

Br

>

CH3

7. Enantiomers have the same physical properties (m.p., b.p., index of refraction, density). (Sec. 6.8) 8. Meso compounds rotate plane polarized light the same magnitude as enantiomers, but in opposite directions. (Sec. 6.5) 9. Diastereomers are achiral. (Sec. 6.5) 10. Enantiomers and meso compounds are diastereomers. (Sec. 6.5)

72

Chapter 6 Chirality

Answers Multiple Choice 1. d 2. b 3. d 4. c 5. c 6. c 7. d 8. d 9. a 10. a 11. c 12. c 13. b 14. a 15. a 16. b 17. c 18. d 19. b 20. d 21. d 22. c 23. c 24. d 25. c Fill in the Blank 1. 2. 3. 4. 5. 6. 7.

3 5 2, 3, 1, 4 2, 1, 3, 4 2R, 3R 1S, 2S

OH

OH 8.

Cl

Br 9. enantiomers 10. diastereomers

73

Chapter 6 Chirality

True-False 1. T 2. T 3. F 4. T 5. F 6. F 7. T 8. F 9. F 10. T

74...