Alcohol

Alcohols are organic compounds containing the –OH functional group. A functional group is the part of a molecule responsible for its characteristic reactions. The first four alcohols form a homologous series: methanol (CH₃OH), ethanol (CH₃CH₂OH), propanol (C₃H₇OH) and butanol (C₄H₉OH).

Alcohols are carbon compounds whose molecules include an –OH group. The first four straight-chain alcohols are methanol, ethanol, propan-1-ol and butan-1-ol.

A name can provide a check: -ane indicates an alkane, -ene an alkene, -ol an alcohol, and -oic acid a carboxylic acid. The beginning of the name tells you about the number of carbon atoms, while the ending tells you the family. For example, ethanol and ethanoic acid both have two carbon atoms, but their endings—and their functional groups—place them in different homologous series.

The first members provide familiar reference points: methane to butane among the alkanes; ethene onwards among the alkenes; methanol to butanol among the alcohols; and methanoic acid to butanoic acid among the carboxylic acids. There is no methene because a C=C bond requires two carbon atoms.