Manipal MET2010ChemistryCarboxylic Acid Derivatives
Consider the acidity of the carboxylic acids I. PhCOOH II. o- NO ₂ C ₆ H ₄ COOH III. p- NO ₂ C ₆ H ₄ COOH IV. m- NO ₂ C ₆ H ₄ COOH Which of the following order is correct?
Options
- AI II III IV
- BII IV III I
- CII IV I III
- DII III IV I
Correct answer
D. II III IV I
Step-by-step solution
-NO ₂ group at any position shows electron withdrawing effect, thus acid strength is increased. But o-nitro benzoic acid believed to have ortho effect. As a result, resonance gets prevented. Hence, its acid strength is maximum, thus, the order of acid strength (II) (III) (IV) (I) (The effect is more at para position than meta.)