alkanoic

Alkanoic is an adjectival stem used in chemistry to describe alkanoic acids, a class of aliphatic carboxylic acids. They are formed when a hydrogen atom on an alkane is replaced by a carboxyl group (-COOH), yielding a general formula for straight-chain members of the series as R-COOH, where R is an alkyl group. This creates a homologous series in which the carbon skeleton length increases by one carbon at a time.

Nomenclature and examples follow the pattern of the root alkane with the suffix -anoic acid. Common members include methanoic (formic) acid, ethanoic (acetic) acid, propanoic (propionic) acid, and butanoic (butyric) acid. The series also encompasses longer-chain fatty acids such as hexanoic, octanoic, and beyond. The term alkanoic acid emphasizes the saturated carbon chain as opposed to aromatic or unsaturated carboxylic acids.

Key properties of alkanoic acids arise from the carboxyl group. They are weak acids, typically with pKa values around 4–5 for the smaller members; acidity is relatively consistent across the series, though solubility in water decreases as the alkyl chain length increases. Lower members are miscible with water, while longer chains are hydrophobic. They participate in esterification with alcohols to form esters and in neutralization reactions to give carboxylate salts; they are also subjects of oxidation and reduction in various chemical contexts.

Industrial and biological relevance is broad, including vinegar (acetic acid), propionic acid as a preservative, and fatty acids found in fats and oils.