Question

An incorrect statement with respect to ${\text{S}}_{\text{N}}1$ and ${\text{S}}_{\text{N}}2$ mechanism for alkyl halide is

• A. A strong nucleophile is an aprotic solvent increases the rate or favours ${\text{S}}_{\text{N}}2$ reaction.
• B. Competing reaction for ${\text{S}}_{\text{N}}2$ reaction is rearrangement
• C. ${\text{S}}_{\text{N}}1$ reactions can be catalysed by some Lewis acids
• D. A weak nucleophile and a protic solvent increases the rate of ${\text{S}}_{\text{N}}1$ reaction

Answer 1

Answer: (B)

${\text{S}}_{\text{N}}1$ reaction occurs through the formation of carbocation as intermediate. Hence, rearrangement occurs in ${\text{S}}_{\text{N}}1$ reaction and not in ${\text{S}}_{\text{N}}2$ reaction. ${\text{S}}_{\text{N}}1$ reaction is favoured in presence of a polar protic solvent and a weak nucleophite. These reactions can be catalysed by the some Lewis is acid. A strong nucleophile is an aprotic solvent increases the rate of ${\text{S}}_{\text{N}}2$ reaction. Hence, option $(\text{B})$ in incorrect.