Question

Choose the correct statement for the given reaction

• A. Trans 2-thio-substituted chloro cyclohexane reacts faster than cis 2-thio-substituted chloro cyclohexane
• B. Cis 2-thio-substituted chloro cyclohexane reacts faster than trans 2-thio-substituted chloro cyclohexane
• C. Both cis and trans isomer reacts at equal rate
• D. Cannot be said

Answer 1

The correct option is A Trans 2-thio-substituted chloro cyclohexane reacts faster than cis 2-thio-substituted chloro cyclohexane

The given compound has sulphur which is a neighbouring group. It will act as nucleophile and undergo $S_{N}NGP$ reaction.
One of the conditions for neighbouring group participation reaction is that the nucleophile and the leaving group should be in anti position.
In cyclohexane derivative 1, 2 trans will have groups at anti position and 1, 2 cis have groups at syn positions.

Hence, trans 2-thio-substituted chloro cyclohexane undergo $S_{N}NGP$ reaction and it is faster than normal intermolecular reaction.

Reaction mechanism: