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Among the following benzylic carbocations formed on a methyl-substituted benzene ring, which is the most stable?

1. para-CH3 relative to the +CH2 (benzylic cation) center
2. meta-CH3 relative to the +CH2 center
3. ortho-CH3 relative to the +CH2 center
4. None of these

Correct answer: para-CH3 relative to the +CH2 (benzylic cation) center

Solution

A methyl group is electron-releasing and stabilizes the benzylic cation through hyperconjugation and +I when located at the positions that bear positive charge in resonance (ortho/para). The para position avoids the steric strain present at ortho, so the para-methyl benzylic cation is most stable; meta cannot stabilize by resonance.

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