Question

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

• A. amino acids exists as zwitter ions resulting in strong dipole-dipoles attraction
• B. Amino acids are optically active
• C. Due to higher moleculear 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 exists as zwitter ions resulting in strong dipole-dipoles attraction

Answer 2

Amino acids exist as zwitter ions,

$H_{3}\overset{+}{N} - OHR - COO^{-}.$ Because of this dipolar attractions. Character, they have strong dipole-dipole attractions. Hence, their melting points are higher then halo-acids.