In alcohols,
the boiling points decrease with increase of branching in carbon chain
(because of decrease in van der Waals forces with decrease in surface
area) The –OH group in alcohols and phenols is involved in intermolecular
hydrogen bonding as shown below:
It is interesting to note that boiling points of alcohols and phenols
are higher in comparison to other classes of compounds, namely
hydrocarbons, ethers, haloalkanes and haloarenes of comparable
molecular masses For example, ethanol and propane have comparable
molecular masses but their boiling points differ widely The boiling
point of methoxymethane is intermediate of the two boiling points