Question Detail

CHM 102 Practice Questions Objective Question

Question

Which of the following correctly reflects relative stabilities of carbocations?
Options
A 3° allylic > 2° > 1° benzylic
B methyl > 2° benzylic > 3°
C 3° benzylic > vinyl > 1°
D 2° allylic > 2° > vinyl
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

The correct order of carbocation stability is: 2° allylic > 2° > vinyl. Allylic and benzylic carbocations are stabilized by resonance. Vinyl carbocations are very unstable. Methyl is least stable. 3° benzylic > 3° allylic > 3° > 2° benzylic > 2° allylic > 2° > 1° benzylic > 1° allylic > 1° > vinyl.

Hint

How does resonance and substitution affect carbocation stability?

Question Info