Question

For the given pair of reactions, predict the faster one and mechanism ($S_{N}1$ or $S_{N}2$) under which reaction will occur at faster rate.

• A. $\left(i\right)>\left(ii\right)$
• B. $\left(i\right)<\left(ii\right)$
• C. $\left(i\right)=\left(ii\right)$
• D. None of these

Answer 1

Answer: (A)

$\left(i\right)>\left(ii\right)$

The reaction (i) is faster than reaction (ii)

Reaction (i) is $S_{N}2$ reaction of primary alkyl halide. It is one step reaction.

Reaction (ii) is $S_{N}1$ reaction of tertiary alkyl halide. In this reaction, the rate determining step is the formation of carbocation and is a slow step.