Glycine exists as a Zwitter ion but 0‐and p‐amino benzoic acids do not. Explain.

Question

Glycine exists as a Zwitter ion but O and p‐amino benzoic acids do not. Explain.

Answer 1

The lone pair of N‐atom in O‐ and p‐aminobenzoic acid is involved in resonance. The lone pair of N‐atom in transferred towards benzene ring. This decreases the acidic character of –NH2 group. Therefore these groups do not transfer and accept H+ ions, respectively.