Question

M-methylbenzoic acid or p-methyl benzoic acid is more acidic

Answer 1

THE ORTHO EFFECT:- This is a special effect shown by benzene and its derivatives , but is not necessarily a steric effect. Nearly all o-substituted benzoic acids are stronger than the benzoic acid. Benzoic acid is a resonance hybrid, and so the carboxyl group is coplanar with the ring. Any o- substituent tends to prevent this coplanarity. Thus, resonance is diminished resulting in increased acidic strength.

The ortho effect is responsible for ortho methyl benzoic acid to be more acidic than para methyl benzoic acid. In a general trend, ortho substituted acids are stronger than their counterparts.

Similarly, ortho substituted bases are weaker than their counterparts.

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