JEE Main Chemistry question

Consider the acidity of the carboxylic acids (i) PhCOOH, (ii) o-NO₂C₆H₄COOH, (iii) p-NO₂C₆H₄COOH, (iv) m-NO₂C₆H₄COOH. Which of the following orders is correct?

(A)(I) > (II) > (III) > (IV)
(B)(II) > (IV) > (III) > (I)Correct
(C)(II) > (IV) > (III) > (I) (duplicate phrasing of option b)
(D)(II) > (III) > (IV) > (I)

Answer: (B)

Solution

The strongly electron-withdrawing –NO₂ group increases acidity relative to unsubstituted benzoic acid regardless of position (by induction, reinforced by resonance at ortho/para). The ortho isomer is further strengthened by the additional proximity (field) effect and some steric inhibition of resonance in the neutral

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Question ID VK-149260