ABSTRACT
Hydrogen-hydrogen bond is the main intermolecular interaction in alkanes and some alkenes, and it is a secondary intermolecular interaction in alcohols, ethers, and amines. Any molecule with saturated long hydrocarbon chain has hydrogen-hydrogen bond. A broader view of the intermolecular interactions is given by the non-covalent interaction theory. The p-stacking interaction occurs between two benzene molecules or any pair of phenyl ring which are displaced from one another so that one carbon of a phenyl ring interacts with the other carbon of the other phenyl ring, i.e., it is a C-C interaction between displaced phenyl rings. The dipole moment vector arises from the electronegativity difference between the bonding atoms. Carboxylic acid and ester have smaller dipole moments than aldehyde and ketone because dipole moment components in carboxylic acid and ester have somewhat opposite directions decreasing the dipole moment resultant in comparison with that from aldehyde and ketone.
