Question

The increasing order of the reactivity of the following halides for the $S_{N}1$ reaction is:

$\begin{array}{ccc}\underset{\stackrel{|}{Cl}}{C{H}_{3}CHC{H}_{2}C{H}_3}& C{H}_{3}C{H}_{2}C{H}_{2}Cl& p-H_{3}CO-C_6{H}_4-C{H}_{2}Cl\\ \left(I\right)& \left(II\right)& \left(III\right)\end{array}$

• A. (II) < (I) < (III)
• B. (I) < (III) < (II)
• C. (II) < (III) < (I)
• D. (III) < (II) < (I)

Answer 1

The correct option is A (II) < (I) < (III)

Rate of $S_{N}1\propto$ carbocation stability

$\begin{array}{ccc}\underset{⨁}{C{H}_{3}CHC{H}_{2}C{H}_3}& C{H}_{3}C{H}_{2}C{H}_2^{⨁}& p-C{H}_{3}O-C_6{H}_5-C{H}_2^{⨁}\\ \left(I\right)& \left(II\right)& \left(III\right)\end{array}$

$\therefore$ II < I < III