Organic Chemistry

436 CHAPTER 11 Elimination Reactions of Alkyl Halides • Competition Between Substitution and Elimination

44. For each of the following reactions, give the elimination products; if the products can exist as stereoisomers, indicate which
    stereoisomers are obtained.
    a.
    b.
    c.
    d.
    e.


45. Which of the following hexachlorocyclohexanes is the least reactive in an E2 reaction?


46. The rate of the reaction of 1-bromo-2-butene with ethanol is increased if silver nitrate is added to the reaction mixture. Explain.


47. For each of the following reactions, carried out under conditions, give the products; if the products can exist as
    stereoisomers, show which stereoisomers are formed.
    a. c.
    b. d.


48. Two elimination products are obtained from the following E2 reaction:

a. What are the elimination products?

b. Which is formed in greater yield? Explain.

49. Three substitution products and three elimination products are obtained from the following reaction:

Account for the formation of these products.

50. When the following stereoisomer of 2-chloro-1,3-dimethylcyclohexane reacts with methoxide ion in a solvent that encourages
    reactions, only one product is formed:

When the same compound reacts with methoxide ion in a solvent that favors reactions, twelve products are formed. Identify

the products that are formed under the two sets of conditions.

51. For each of the following compounds, give the product that will be formed in an E2 reaction and indicate the configuration of the
    product:
    a. (1S,2S)-1-bromo-1,2-diphenylpropane b. (1S,2R)-1-bromo-1,2-diphenylpropane

SN 1 >E1

CH 3

CH 3

H

H

Cl

H

SN 2 >E2

H 3 CCH 3

CH 3 OH

Br

+

H 3 CCH 3

OCH 3

H 3 C OCH 3 C

CH 3

CH 3

OCH 3

H 3 C

++

H 3 CCH 3 CH (^3) C
CH 3
CH 3
CH 3
+++
HO−
CH 3 CH 2 CHDCH 2 Br
(3S,4R)-3-bromo-4-methylhexane+CH 3 O- (3R,4S)-3-bromo-4-methylhexane+CH 3 O-
(3S,4S)-3-bromo-4-methylhexane+CH 3 O- (3R,4R)-3-bromo-4-methylhexane+CH 3 O-
SN 2 >E2
Cl Cl
Cl Cl
Cl
Cl
Cl Cl
Cl Cl
Cl
Cl
Cl Cl
Cl Cl
Cl
Cl
Cl Cl
Cl Cl
Cl
Cl
3-chloro-3-ethyl-2,2-dimethylpentane+high concentration of CH 3 CH 2 O-
(2R,3R)-2-chloro-3-methylpentane+high concentration of CH 3 O-
(2R,3S)-2-chloro-3-methylpentane+high concentration of CH 3 O-
(2S,3R)-2-chloro-3-methylpentane+high concentration of CH 3 O-
(2S,3S)-2-chloro-3-methylpentane+high concentration of CH 3 O-
BRUI11-400_436r3 26-03-2003 10:20 AM Page 436