Question

Write structures of various carbocations that can be obtained from 2-methylbutane. Arrange these carbocations in order of increasing stability.

Answer 1

(i)	\[\begin{array}{cc} \ce{CH3 - CH - CH2 - \overset{+}{C}H2}\\ |\phantom{.......}\\ \ce{CH3}\phantom{......} \end{array}\]
(ii)	\[\begin{array}{cc} \ce{CH3 - CH - \overset{+}{C}H - CH2}\\ |\phantom{.......}\\ \ce{CH3}\phantom{......} \end{array}\]
(iii)	\[\begin{array}{cc} \ce{CH3 - \overset{+}{C} - CH2 - CH3}\\ |\phantom{.......}\\ \ce{CH3}\phantom{......} \end{array}\]
(iv)	\[\begin{array}{cc} \ce{\overset{+}{C}H2 - CH - CH2 - CH3}\\ |\phantom{.......}\\ \ce{CH3}\phantom{......} \end{array}\]

The stability order is found to be: (III) > (II) > (I) > (IV)

This is because (III) is tertiary carbocation, (II) is secondary carbocation, (I) and (IV) are primary.