Question

Which of the following pair of compound will have the same order of rate of $S_{N}1$ and $S_{N}2$ ?

• A. II and IV
• B. I, II and III
• C. I, II, III and IV
• D. III only

Answer 1

The correct option is B I, II and III

Order of rate of $S_{N}1$ and $S_{N}2$
(Resonance stabilization)
(Resonance stabilisation)
(Resonance stabilisation)

In all the above three, the first substrate is more reactive towards both $S_{N}1$ and $S_{N}2$.
In $S_{N}1$ reaction, the carbocation is stabilized by resonance.
In $S_{N}2$ reaction, the substrates are more electrophilic because of -I effect of O, double bond and benzene.