In general, industrial routes to carboxylic acids differ from those used on a smaller scale because they require specialized equipment.
* Carbonylation of alcohols as illustrated by the Cativa process for the production of acetic acid. Formic acid is prepared by a different carbonylation pathway, also starting from methanol.
* Oxidation of aldehydes with air using cobalt and manganese catalysts. The required aldehydes are readily obtained from alkenes by hydroformylation.
* Oxidation of hydrocarbons using air. For simple alkanes, this method is inexpensive but not selective enough to be useful. Allylic and benzylic compounds undergo more selective oxidations. Alkyl groups on a benzene ring are oxidized to the carboxylic acid, regardless of its chain length. Benzoic acid from toluene, terephthalic acid from para-xylene, and phthalic acid from ortho-xylene are illustrative large-scale conversions. Acrylic acid is generated from propene.
* Oxidation of ethene using silicotungstic acid catalyst.
* Base-catalyzed dehydrogenation of alcohols.
* Carbonylation coupled to the addition of water. This method is effective and versatile for alkenes that generate secondary and tertiary carbocations, e.g. isobutylene to pivalic acid. In the Koch reaction, the addition of water and carbon monoxide to alkenes or alkynes is catalyzed by strong acids. Hydrocarboxylations involve the simultaneous addition of water and CO. Such reactions are sometimes called "Reppe chemistry."
* Hydrolysis of triglycerides obtained from plant or animal oils. These methods of synthesizing some long-chain carboxylic acids are related to soap making.
* Fermentation of ethanol. This method is used in the production of vinegar.
* The Kolbe–Schmitt reaction provides a route to salicylic acid, precursor to aspirin.