Question

Tertiary alkyl halides are practically inert to substitution by $S_{N}2$ mechanism because?

• A. the carbocation formed is unstable
• B. there is steric hindrance
• C. there is inductive effect
• D. the rate of reaction is faster in $S_{N}2$ mechanism.

Answer 1

The correct option is B there is steric hindrance

The repulsion between the alkyl or any other groups present on an carbon atom, if the distance between the two is less than vander waals radius, than it is said to be the steric hindrance. That is the reason why tertiary alkyl halides are practically inert to substitution by $S_{N}2$ mechanism as there is steric hindrance.