Question

Find the strongest acid among the following compounds.

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

Carboxylic acid groups are more acidic than alcohol group. Hence option (b) is least acidic.
In option (a), (c) and (d) we have functional group in ortho position which will increase the acidity of the compound than normal benzoic acid due to ortho effect. In option (a) and (d), the substituent is +I group so it will increase electron density on carboxylate ion and it get destabilise so it will be less acidic.
In option (c), the substituent is -I group so it will decrease the electron density on carboxylate ion which make it more stable, hence the compound is more acidic in nature.