Question

Arrange the following compounds in order of their reactivity towards $S_N^2$ reaction.
(i) $C{H}_3(C{H}_2{)}_{3}C{H}_{2}Br$
(ii)$C{H}_3\left(C{H}_2\right)CHC{H}_{2}C{H}_{2}Br$
(iii)$C{H}_3-C{H}_2\stackrel{C{H}_3}{\stackrel{|}{CH}}-C{H}_{3}Br$
(iv)=$C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{C{H}_3}{\underset{|}{C}}}}-C{H}_{3}Br$

• A. i > ii > iii > iv
• B. ii > iii> iv >i
• C. iii > i > ii > iv
• D. iv > ii > i >iii

Answer 1

The correct option is A i > ii > iii > iv

The $S_{N}2$ reaction is prone to steric inhibition. Th order of reactivity of alkyl halide is $1^{\circ }>2^{\circ }>3^{\circ }$.

The $S_{N}2$ reaction follows a particular order as the crowding around C-X bond increases the steric inhibition increases. The order of reactivity of the halides are R - I > R -Br > R -Cl > R - F

Therefore A is the correct option.