Question

Which alkyl halide from the following pair is

1. chiral
2. undergoes faster S_N2 reaction?

Answer 1

i.  

\[\begin{array}{cc}\ce{H}\phantom{..........}\\|\phantom{..........}\\\ce{CH3 - C∗ - CH2 - CH3}\\
|\phantom{..........}\\\ce{Br}\phantom{.........}\end{array}\]

Here the C* is chiral carbon atom and it is surrounded by four different groups.

ii. 

i.e., 1-chiorohutane undergoes faster S_N² reaction. CH₃-CH₂-CH₂Cl is a primary alkyl halide and so it undergoes faster S_N² reaction.