Question

The most reactive towards $S_{N}1$ is:

• A. $PhC{H}_{2}Cl$
• B. $PhCl$
• C. $PhCHCl\left(C{H}_3\right)$
• D. $p-N{O}_2{C}_6{H}_{4}C{H}_{2}Cl$

Answer 1

The correct option is C $PhCHCl\left(C{H}_3\right)$

${SN}^1$ reaction involves formation of carbocation intermediate. More the stability of carbocation more is the reactivity of Alkyl / Aryl halides towards ${SN}^1$.

The intermediate carbocations formed by given halides as $Ph-\stackrel{(+)}{CH}-{CH}_3$ is more stable than others due to resonance in phenyl ring and inductive effect of ${CH}_3$ group.