Question

The order of rate of hydrolysis of alkyl halides: $1^{\circ}, 2^{\circ}, 3^{\circ}$ and $CH_3X$ by $S_N2$ pathway is

• A. $1^{\circ} > 2^{\circ} > 3^{\circ} > CH_3X$
• B. $CH_3X > 3^{\circ} > 2^{\circ}> 1^{\circ} $
• C. $ CH_3X > 1^{\circ} > 2^{\circ} > 3^{\circ} $
• D. $3^{\circ} > 2^{\circ} > 1^{\circ} > CH_3X$

Answer 1

Answer: (C)

Reactivity in $S_N2$ reactions depends upon the steric hindrance. Since the steric hindrance increases in the order: $ CH_3X > 1^{\circ} > 2^{\circ} > 3^{\circ} $ °, therefore, reactivity in $S_N2$ reactions decreases in the same order, i.e., option (c) is correct.