Physical Properties of Alcohols

Lower alcohols are colourless liquids; higher members are waxy solids. Alcohols have markedly higher boiling points than alkanes, aldehydes or ethers of comparable molar mass, because of intermolecular hydrogen bonding between the -OH groups (Table 11.2 compares butane, propanal and methoxyethane, all molar mass 58-60, against propan-1-ol and propan-2-ol, both molar mass 60 but boiling far higher). Among isomeric alcohols, PRIMARY alcohols have the highest boiling point and TERTIARY alcohols the lowest, since a bulkier, more branched tertiary alcohol packs less efficiently and hydrogen-bonds less effectively than a linear primary one. Lower alcohols are highly water-soluble because the …