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How do hydrogen bonds form between alcohol molecules?

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Hydrogen bonds form between alcohol molecules due to the presence of the hydroxyl group (―OH), which contains a strongly polarized oxygen-hydrogen bond.12

Because the oxygen atom is significantly more electronegative than the hydrogen atom, it pulls electron density away from the hydrogen. This results in the hydrogen atom bearing a partial positive charge, while the oxygen atom carries a partial negative charge.12

The hydrogen bond occurs when this partially positive hydrogen atom is attracted to a pair of nonbonding electrons on the oxygen atom of a neighboring alcohol molecule. These intermolecular forces are significantly weaker than covalent bonds, yet they are strong enough to significantly influence the physical properties of alcohols, such as resulting in higher boiling points compared to alkanes of similar molecular weight.2