The melting points and solubility in water of amino acids are higher than those of the corresponding halo acids. Explain.
The amino acids exist as zwitterions, H3N+–CHR COO–. Due to this dipolar salt like character they have strong dipole-dipole attractions or electrostatic attractions. Therefore, their melting points are higher than haloacids which do not have salt like character. Further, due to salt like character, they interact strongly with H2O. As a result, solubility in water of amino acids is higher than that of the corresponding haloacids which do not have salt like character.