Question

Why do amines have higher boiling points than hydrocarbons?

Answer 1

Hint: Any molecule having intramolecular hydrogen bonding or intermolecular hydrogen bonding is soluble in water or any aqueous solution. Hydrogen bonding is the bonding of any atom or electrons from a compound to a hydrogen in water.

Complete answer:
Polarity in a compound is defined as the eagerness of an atom to gain electrons from another atom of another element or maybe the same element.
Now in a hydrocarbon, all the bonds that exist in it are all of hydrogen and carbon and by carbon and carbon. Now hydrogen is more electropositive than carbon and carbon has no electron to have while there is some polarity between the two carbons.
Now all these bonds that amines have in them are hydrogen and carbon, carbon and carbon and between carbon and nitrogen and obviously between nitrogen and hydrogen. Now hydrogen is a very electropositive atom so nitrogen and carbon don’t have much polarity there. Next the bond between carbon and carbon is fairly polar. Now the bond between nitrogen and carbon is very polar because nitrogen has higher electronegativity and also nitrogen has one unpaired electron with it in a tetrahedral structure.
Amines have higher boiling points than hydrocarbons as well because due to higher polarity between carbon and nitrogen bonds, they are more soluble and make stronger hydrogen bonds. Now as the hydrogen bonding is higher, therefore the boiling point is higher.
Amines have higher boiling point than hydrocarbon due to hydrogen bonding.

Note:
Primary amines have higher hydrogen bonding than tertiary amines due to steric hindrance of the bulky alkyl group.