Two types of hydrogen bonding have been recognized: Intermolecular and intramolecular hydrogen bonding. Intermolecular means within the same molecule and Intramolecular are the forces within two atoms in a molecule. Due to hydrogen bonding, there is an increase in intermolecular aggregation forces which is reflected in the boiling point and solubility of the organic compound.
This is a special kind of dipole-dipole interaction that occurs specifically between a hydrogen atom bonded to either oxygen, nitrogen, or fluorine atom. Intermolecular hydrogen bond results in the association of molecules. Hence, it usually increases the melting point, boiling point, viscosity, surface tension, solubility, etc. Each of the elements to which the hydrogen is attached is not only significantly negative but also has at least one ‘active’ lone pair.
Intermolecular hydrogen bond formation lowers the strength of an acid. For example, HBr is weaker than HI and H2O is weaker than H2S. For a substance to be soluble in water, it should be able to make a hydrogen bond with water. Any molecule which has a hydrogen atom attached directly to an oxygen or nitrogen is capable of hydrogen bonding. Such molecules will always have higher boiling points than similarly sized molecules which don’t have an -O-H or an -N-H group. Hydrogen bonding also occurs in organic molecules containing N-H groups – in the same sort of way that it occurs in ammonia. Examples range from simple molecules like CH3NH2 (methylamine) to large molecules like proteins and DNA.