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JEE Main levelSingle correct optionDifficulty 2 of 3co266

The acid shown has whereas its para isomer has . The main reason for the greater acidity of the drawn acid is

  1. AThe nitro group donates electrons by +M to the ring at the ortho position
  2. BIntermolecular hydrogen bonding makes the ortho acid a dimer
  3. CThe nitro group blocks solvation of the carboxylate and so stabilises it
  4. DThe ortho nitro group twists the COOH out of the ring plane and its -I effect acts over a short distance, strongly stabilising the carboxylate

Answer: D

The drawn compound is 2-nitrobenzoic acid (ortho effect). Steric inhibition of resonance removes conjugation between COOH and the ring (making the acid stronger), and the -I effect of NO2 is largest at the ortho position. The nitro group does not donate electrons.
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