Question

Which of the following halides will be most reactive in $S{N}^2$ reaction and $S{N}^1$ reaction, respectively?

• A. (I), (II)
• B. (II), (I)
• C. (I), (III)
• D. (III), (I)

Answer 1

The correct option is C

(I), (III)

$\left(I\right)\Rightarrow 1^{\circ }$ allylic halide and less steric hindrance, hence $S{N}^2$.
$\left(III\right)\Rightarrow 3^{\circ }$ allylic halide, most stable carbonium ion and hence $S{N}^1$.