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Arrange the following benzylic carbocations in correct order of decreasing stability: (1) p-HO-C6H4-CH2+ (2) p-H2N-C6H4-CH2+ (3) p-CH3-C6H4-CH2+ (4) p-(CH3)3C-C6H4-CH2+

1. 2 > 1 > 4 > 3
2. 1 > 2 > 4 > 3
3. 3 > 4 > 2 > 1
4. 2 > 1 > 3 > 4

Correct answer: 2 > 1 > 4 > 3

Solution

p-NH2 (strongest +M) > p-OH (strong +M) > p-(CH3)3C (more hyperconjugation than methyl) > p-CH3. Order: 2 > 1 > 4 > 3.

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