Organic Chemistry

Problems 237

84. Two stereoisomers are obtained from the reaction of HBr with (S)-4-bromo-1-pentene. One of the stereoisomers is optically active,
    and the other is not. Give the structures of the stereoisomers, indicating their absolute configurations, and explain the difference in
    optical properties.


85. When (S)- -1-chloro-2-methylbutane reacts with chlorine, one of the products formed is -1,4-dichloro-2-methylbutane. Does
    this product have the Ror the Sconfiguration?


86. Indicate the configuration of the asymmetric carbons in the following molecules:

a. b. c.

87. a. Draw the two chair conformers for each of the stereoisomers of trans-1-tert-butyl-3-methylcyclohexane.
    b. For each pair, indicate which conformer is more stable.


88. a. Do the following compounds have any asymmetric carbons?
    
    
    1. 
       
       
       
       2. b. Are they chiral? (Hint:Make models.)
       
       
       
       
    
    
    
    

CH 2 “C“CH 2 CH 3 CH“C“CHCH 3

OH

H

H

Br

CH 3

O

O CH 2 CH 3

CH 3

(+) (-)