Question

Pick out most reactive alkyl halide for $S_{N}1$ reaction.

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Since the rate determining step of $S_{N}1$ reaction involves Carbocation formation.
$\text{Rate of reaction}\propto \text{Stability of carbocation}$
(a) will form $3^o$ carbocation which is most stable thus tertiary halide would be most reactive in $S_{N}1$ reaction.
c and d will form secondary carbocation while b will form primary carbocation.