Question

Arrange the following in increasing order of stability

$\text{(A)}(C{H}_3{)}_2\stackrel{\oplus }{C}-C{H}_{2}C{H}_3$
$\text{(B)}(C{H}_3{)}_3-\stackrel{\oplus }{C}$
$\text{(C)}(C{H}_3{)}_2-\stackrel{\oplus }{C}H$
$\text{(D)}C{H}_3-\stackrel{\oplus }{C}{H}_2$
$\text{(D)}\stackrel{\oplus }{C}{H}_3$

• A. $A<E<D<C<B$
• B. $E<D<C<B<A$
• C. $D<E<C<A<B$
• D. $E<D<C<A<B$

Answer 1

The correct option is D $E<D<C<A<B$

Greater the number of $e^{-}$ donating alkyl groups (+I effect), greater will be the stability of carbocations.
Greater the number of $\alpha$-H, more will be hyperconjugation, greater will be the stability of carbocations.

A is secondary carbocation and has eight $\alpha$-H.
B is tertiary carbocation and has nine $\alpha$-H.
C is primary carbocation and has three $\alpha$-H.
D is methyl carbocation.
Hence stability order is $E<D<C<A<B$