Why do primary amines have higher boiling point than tertiary amines?

Explanation

Out of `1^@, 2^@` and `3^@` amines `1^@` amines have highest boiling point while `3^@` amines have lowest boiling point. For example :
`NH_3 , CH_2CH_2NH_2 , CH_2 - CH_2 - NH - CH_2 , CH_3 - oversetunderset(|)(CH_3)(N) - CH_3`
Out of these amines, n-propylamine have highest boiling while trimethyl amine(39 have lowest boiling point. This is because H-bonding is most extensive in `1^@` amines in which two H-atoms are directly attached to N which take part in H-bonding. In case of `3^@` amine no H-bonding is possible as no H-atom is directly attached to Nitrogen. As we know H-bonding leads to stronger intermolecular forces and hence higher boiling point.