Propionic acid (from the Greek words protos, meaning “first”, and pion, meaning “fat”; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula C2H5COOH. It is a liquid with a pungent and unpleasant smell somewhat resembling body odor. The anion CH3CH2CO2− as well as the salts and esters of propionic acid are known as propionates (or propanoates).
