Question

2-iodo cyclohexyl acrylate undergoes acetolysis. Which of the following statement(s) is/are true?

• A. Trans-isomer of the substrate undergoes acetolysis 670 times faster than that of its cis-isomer.
• B. Cis-isomer of the substrate undergoes cytolysis 670 times faster than that of its trans-isomer.
• C. Both isomers undergo cytolysis with the same rate.
• D. The enhanced rate of this nucleophilic substitution is due to neighbouring group participation.

Answer 1

Answer: (A), (D)

The correct options are
A Trans-isomer of the substrate undergoes acetolysis 670 times faster than that of its cis-isomer.
D The enhanced rate of this nucleophilic substitution is due to neighbouring group participation.

Trans-2-iodo cyclohexyl acrylate undergoes acetolysis (nucleophilic substitution) 670 times faster than the cis-isomer. The reaction of the trans-isomer proceeds through participation of neighbouring group, i.e., iodo group. Such neighbouring group participation by iodo group is not possible in the cis-isomer. Hence, cis-isomer undergoes the normal $S_{N}2$ mechanism.