1  

Organic Chemistry I Test 2 Extra Stereochemistry Practice Problems Page 1: Designate R/S Page 2: Chiral or Achiral? Page 3: Same, Enantiomer, or Diastereomer? A. Designate the R/S configuration for any chiral centers in the following molecules.

1.

2. 3.

4. 5.

6.

7.

8. 9.

10.

11. 12.

13.

14.

15.

16.

17.

18.

19.

20. 21.

22.

23. 24.

25.

26.

27.

28. 29. 30.

BrH HBr HH2N

BrHHO

H OH OHHHO

OHH

HO O NH2

H OHO H OH

OHBrH

HOO O

CH3H

O O

CH3H

NH

O

CH3HNH2

OHHHO OH

OHH

O

OHH

O HH3CO

CH3H

OHHO

NH2

H CH3 OHHH2N

OHH

CH3Br

CH3 CH3H HHO

O

H

NH2H

H

NH2H3C HCH3 CH3H HO

CH3 CH3H H

CH3HO

HCH3H H OH

O

H HClHO O

CH2OHHH

HOHO

H HHOHOH

OH3C

H

R, not S. Error in movie

R,RR,R, error in movie which said R, S.

This one is very hard.But for each of the 5 chiral C's, the tie-breaking processes do work.

  2   B. Identify each of the following molecule as chiral or achiral. (By circling the chiral ones.) Write “meso” where it applies. (In other words, if it is achiral despite having chiral centers).

31.

32.

33.

34.

35. 36.

37.

38. 39.

40.

41.

42. 43.

44.

45.

46.

47. 48.

49.

50.

51. 52. 53.

NH

O

CH3HNH2

OHHHO OH

OHH

O

HH3CO HH3CO

CH3H

HH3C

OHH

OHH O

Cl ClHH Cl HH

Cl

ClH

HCl

ClH

ClH

Cl ClHH Cl BrH

H

OH

OH

OH

OH

OH

CH3

OH

HOHH

OH

OHHH

Cl

CH3

H

Cl

CH3

HCl

CH3

H

H

CH3

ClCl

CH(CH3)2

H

Cl

CH3

H

T

One chiral carbon => chiral molecule

Two common attachments => achiral

Plane of symmetry => achiral

Problems 51-53, in which you need to translate from a Newman projection, are on the very very difficult end. If you want to challenge yourself, do them. But these are probably harder than you'll see on the test.

  3  

C. Mark the relationships between the following structures as either “same”, “enantiomers”, or “diastereomers”.

54.

55.

56.

57.

58.

59.

60.

61.

62. 63.

64.

65.

66.

67.

68. 69.

70.

71.

72. 73.

74. 75.

76. 77.

ClHClH

ClH Cl H

ClH HCl ClH H Cl

ClHCl

HH3C ClHCl H

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OH

OHOH

OH

OHOH

OH

OHOH

OH

OHOH

OH

OHOH

OH

OHOH

OH

OHOH

OHOH

HOOH

OH

OHOH

ClH

ClH

HCl

HCl

ClH

ClH

HCl

ClH

ClH

HCl

HCl

ClH

Cl ClHH

ClH

HCl

Cl HHCl

ClH

HCl

Cl HHCl

ClH

HCl

OH

OH

OH

HOHH

OH

OHHH OH

OH

Cl

CH3

H

Cl

CH3

HCl ClH

HCl

CH3

H

H

CH3

Cl ClH

ClH

With just one chiral C, if you can assign R/S for both, you can tell if same or different.

64 + 66have some tricky "turning-them-over" issues. Don't worry about them.