Question

Choose the correct statements among the following.

• A. The first step in the both $S_{N}1$ and $E1$ reaction is same
• B. $S_{N}2$ reaction proceed with total retention of configuration
• C. $E2$ eliminations are by the use of polar aprotic solvent and high concentration of a strong base
• D. $S_{N}1$ reaction proceed with total inversion of configuration

Answer 1

Answer: (A), (C)

$E2$ eliminations are by the use of polar aprotic solvent and high concentration of a strong base

(a) First step in both $S_{N}1$ and $E1$ involves dissociation of leaving group and formation of carbocation. Hence, the first step in the both $S_{N}1$ and $E1$ reaction is same.
(b) A $S_{N}2$ reaction proceeds with complete stereochemical inversion while $S_{N}1$ reaction proceeds with racemisation.
(c) $E2$ reactions are favoured by polar aprotic solvents and rate of $E2$ reaction increases as the strength of base increases.
(d) A $S_{N}2$ reaction proceeds with complete stereochemical inversion while $S_{N}1$ reaction proceeds with racemisation.