Question

The carboxylate ion formed due to the deprotonation of the above compound will be most stable, if X is:

• A. $-N{O}_2$
• B. $-N{H}_2$
• C. $-OH$
• D. $-OC{H}_3$

Answer 1

The correct option is A $-N{O}_2$

The stability of carboxylate ion depends upon the $-M$ effect power of the substituent X. If the substituent shows higher $-M$ effect, the carboxylate ion formed will be the most stable.

Among the given substituents only $-N{O}_2$ will show $-M$ effect, all other groups will show $+M$ effect. Therefore, for carboxylate ion to be stable, X has to be $-N{O}_2$.