Question

Arrange the following in the increasing order of their reactivity towards SN1 reactions:

i) 2-bromo-2-methylbutane, 1-bromopentane, 2-bromopentane

ii) 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, 2-bromo-2-methylbutane

Answer 1

In S_N2 reaction, steric factors determine the reactivity. more reactive alkyl halides have less steric hinderance. Hence, the decreasing order of the reactivity of alkyl halides is 1^o >2^o >3^o
 .
(i)  1-Bromopentane >  2-Bromopentane > 2-Bromo-2-methylbutane

(ii) 1-Bromo-3-methylbutane >  2-Bromo-3-methylbutane >  2-Bromo-2-methylbutane