- Propanoic acid (from 'propane', and also known as propionic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent odor. The anion CH3CH2COO- as well as the salts and esters of propanoic acid are known as propanoates (or propionates).
- Propanoic acid has physical properties intermediate between those of the smaller carboxylic acids, formic and acetic acids, and the larger fatty acids. It is miscible with water, but can be removed from water by adding salt.
- In industry, propanoic acid is mainly produced by the hydrocarboxylation of ethylene using nickel carbonyl as the catalyst.
- Propionic acid produced by fermentation is widely used in chemical, pharmaceutical and food industries. It is used primarily for animal feed preservation, including hay, silage and grains and in human foods, mainly in baked goods and cheeses.