Question

Which of the following has maximum stability

• A. $\stackrel{+}{C}{H}_3$
• B. $C{H}_3-\stackrel{H}{\stackrel{|}{\underset{C{H}_2^{-}}{\underset{|}{C}}}}-H$
• C. $C{H}_3-\stackrel{H}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$
• D. $C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$

Answer 1

The correct option is D $C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$

Stability of carbonium ion or carbocation depends on the adjacent alkyl groups. Alkyl groups exhibit electron releasing +I effect and hyperconjugative effect which stabilizes the positive charge. $C{H}_3^{+}$ methyl carbonium ion does not have both of these effects, therefore it is the least stable.

Therefore $C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$ have maximum stability.

Therefore corect answer is option D.

The increasing order of stability is: -

$C{H}_3^{+}$<$C{H}_3-\stackrel{H}{\stackrel{|}{\underset{C{H}_2^{-}}{\underset{|}{C}}}}-H$<$C{H}_3-\stackrel{H}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$ <

$C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{+}{C}}}-C{H}_3$