Consider the acidity of the carboxylic acids (i) \[PhCOOH\] (ii) \[o-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\] (iii) \[p-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\] (iv) \[m-N{{O}_{2}}{{C}_{6}}{{H}_{4}}COOH\] Which of the following order is correct?
A)(i) > (ii) > (iii) >(iv)
B)(ii) > (iv) > (iii) > (i)
C)(ii) > (iv) > (i) > (iii)
D)(ii), > (iii) > (iv) > (i)
Correct Answer:
D
Solution :
(i) (ii) (iii) (iv) group at any position shows electron withdrawing effect thus acid strength is increased. But o-nitro benzoate ion is stabilised by intramolecular H-bonding, hence its acid strength is maximum, The effect is more at para position than meta. Thus, acid strength (II) > (III) > (IV) > (I)