91Ó°ÊÓ

1. Hydrogen bonding, greater the number of hydrogen bonds, the greater will be the boiling point.

2. Electronegativity, more electronegative element has a higher boiling point.

3. Dipole-Dipole interaction, higher these interactions, the more will be the boiling point.

The order of preference is

Here, two groups can make hydrogen bonds so it has the highest boiling point.

Oxygen is more electronegative than nitrogen, therefore the compound is more electronegative.

Nitrogen is less electronegative than oxygen and it is primary amine so it can make better hydrogen bonding than the secondary amine.

Make weak hydrogen bonding than the primary amine.

No hydrogen bonding only weak dipole-dipole interactions.

Weak dipole-dipole interactions and even weaker than oxygen-containing compounds as nitrogen are less electronegative than oxygen.

No dipole-dipole interactions.