Question

Rank the following carbocations in order of stability ($1 =$ most stable)

• A. $A \rightarrow 2, B \rightarrow 1, C \rightarrow 3, D \rightarrow 4$
• B. $A \rightarrow 4, B \rightarrow 2, C \rightarrow 1, D \rightarrow 3$
• C. $A \rightarrow 4, B \rightarrow 3, C \rightarrow 2, D \rightarrow 1$
• D. $A \rightarrow 1, B \rightarrow 2, C \rightarrow 3, D \rightarrow 4$

Answer 1

Answer: (A)

A $-2\left[3^{\circ}\right.$ carbocation with cross conjugation $]$
B $-1\left[2^{\circ}\right.$ carbocation with extended conjugation ]
C - $3 [3$ carbocation with $4$ hyperconjugations and $+1$ of $3$ alkyl groups $]$
D - $4 [ 2^{\circ}$ carbocation with $2$ hyperconjugations and $+I$ of $2$ alkyl groups]
So order will be
$A \rightarrow 2, B \rightarrow 1, C \rightarrow 3, D \rightarrow 4$