Question

Consider the following substitution reaction,

Which of the following statement(s) is/are true?

• A. Reaction occur at much faster rate than when substrate is 2-bromo-3, 3-dimethylpentane
• B. It will follow $S_{N}2$ reaction mechanism
• C. Reaction occurs with inversion of configuration
• D. Both (a) and (c)

Answer 1

The correct option is A Reaction occur at much faster rate than when substrate is 2-bromo-3, 3-dimethylpentane

The substrate have sulphur group which is a neighbouring group. It will act as nucleophile and result in the $S_{N}NGP$ reaction.

When a nucleophile is a part of the reacting molecule, the substitution process is known as intramolecular $S_{N}NGP$.

Intramolecular $S_{N}NGP$ reaction are very fast compared to the intermolecular $S_{N}2$ reactions.

If the substrate is 2-bromo-3, 3-dimethylpentane, then there is no neighbouring group and the reaction becomes intermolecular so its rate will be very slow compare to $S_{N}NGP$.

$S_{N}NGP$ reactions occurs with retention of configuration. There will two inversion in the mechanism of $S_{N}NGP$ which results in a retention of its configuration.