Question

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

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

Answer 1

Answer: (C)

$PhCH\left(Cl\right)C{H}_3$

The rate of $S_{N}1$ reaction depends upon the stability of the carbocation formed.

The compound given in option C forms the most stable carbocation after removal of Cl. This carbocation is most stable due to resonance, hyperconjugation and $+I$ effect of methyl group so it will react easily.

$Ph-\stackrel{\oplus }{C}H-C{H}_3$

Option C is correct.