What primarily influences the high boiling points of alcohols?

The high boiling points of alcohols are primarily influenced by hydrogen bonding. Alcohols contain a hydroxyl group (-OH), which features a highly electronegative oxygen atom bonded to a hydrogen atom. This electronegativity creates a dipole moment, allowing the oxygen to attract the hydrogen of another alcohol molecule. The result is the formation of hydrogen bonds between the alcohol molecules.

These hydrogen bonds are significantly stronger than van der Waals forces, which are relatively weak interactions that occur in other types of molecular compounds. As a consequence, more energy (in the form of heat) is required to break these interactions, leading to higher boiling points for alcohols compared to other molecules of similar molecular weight that do not engage in hydrogen bonding.

While alkyl chain length and molecular weight also play roles in the overall boiling points of substances due to increased van der Waals forces with larger molecules, hydrogen bonding remains the dominant factor in raising the boiling points specifically for alcohols. Therefore, the ability of alcohols to hydrogen bond is directly correlated with their relatively high boiling points.