Question

The melting points of amino acids are higher than the corresponding halo-acids because

• A. amino acids exist as zwitter ions resulting in strong dipole - dipole attraction
• B. amino acids are optically active
• C. due to higher molecular mass of $—NH_{2}$ group molecular mass of amino acids is higher
• D. they interact with water more than halo-acids and have salt like structure.

Answer 1

Answer: (A)

Amino acids exist as zwitter ions, $H_{3}\overset{+}{N} — CHR —COO^{-}.$ Because of this dipolar salt-like character, they have strong dipole-dipole attractions. Hence, their melting points are higher than halo-acids