Question

Tertiary amines have lowest boiling points amongst isomeric amines because:

• A. they have highest molecular mass
• B. they do not form hydrogen bonds
• C. they are more polar in nature
• D. they are most basic in nature

Answer 1

The correct option is B they do not form hydrogen bonds

Primary and secondary amines can form hydrogen bonds whereas tertiary amines fail to do so. Hence, their boiling points are lowest.
In primary amines, two hydrogen atoms are present on N-atom and they undergo extensive intermolecular hydrogen bonding which results in the association of molecules while in tertiary amines, no hydrogen atom is present on N-atom. Hence, there is no hydrogen bonding in tertiary amines. As a result of this, primary amines have a higher boiling point than tertiary amines.