91Ó°ÊÓ

Alcohols and Phenols have greater boiling points due to hydrogen bonding.There is an attraction of +ve polarized –OH hydrogen and -ve polarized oxygen, and they both hold the molecule closer together, which increases the boiling point.

Generally, a series of isomers with branching has a low boiling point. The more nearly a compound becomes spherical, the more the surface area will become less than a straight chain compound with the same molecular weight and functional group present. The smaller the surface area of the compound, the fewer will be the van der Waals interactions (weak forces), which causes the covalent molecules to get attracted to one another.

Moreover, branching in alcohol compounds makes it more difficult for OH groups to approach each other and form hydrogen bonds. Thus, 2-methyl-2-propanol contains fewer hydrogen bonds than 1-Butanol having the same volume, and less energy is required to break them in boiling.