Question

Which of the following is not stereospecific?

• A. $S_{N}1$
• B. $S_{N}2$
• C. Electrophilic substitution
• D. Addition of $B{r}_2$ to ethylene in $CC{l}_4$

Answer 1

The correct option is A $S_{N}1$

$S_{N}1$ mechanism proceeds through carbocation formation. Here, the compound's configuration doesn't change during the reaction, so it is not stereospecific.
$S_{N}2$ mechanism proceeds through transition state formation, in this mechanism, the basic configuration of the compound changes so it is stereospecific.
Also, in electrophilic substitution reaction and free radical mechanism, configuration changes so both are stereospecific.

The correct option is the $A$: $S_{N}1$ mechanism.