Question

Arrange the following compounds in order of their reactivity towards $S_N2$ reaction.
(i) $CH_3(CH_2)_3CH_2Br$
(ii) $(CH_3)_2CHCH_2CH_2Br$

• A. $(i) > (ii) > (iii) > (iv) (b)$
• B. $(ii) > (iii) > (iv) > (i)$
• C. $(iii) > (i) > (ii) > (iv)$
• D. $(iv) > (ii) > (i) > (iii)$

Answer 1

Answer: (A)

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 $R - I > R - Br > R$ $- Cl > R - F$