CH3CH2COO

Propanoate, commonly called propionate, refers to the anionic form CH3CH2COO− derived from propionic acid (CH3CH2COOH). In this carboxylate, the negative charge is delocalized over the two oxygen atoms of the carboxylate group, giving resonance stabilization. The ion consists of a three-carbon alkyl chain attached to a carbonyl-bearing carbon, resulting in a small, polar, and relatively flexible molecule.

In chemistry, propanoate forms salts with various cations, such as sodium propanoate (NaCH3CH2COO) and calcium propanoate (Ca(C2H5COO)2). These salts are typically white, water-soluble solids. The free propanoate ion is a weak base and predominates over its protonated form at neutral pH; the conjugate acid, propionic acid, has a pKa around 4.87.

Occurrence and production: Propanoate occurs as a metabolite produced by microbial fermentation in the gut and is also generated industrially by neutralizing propionic acid. In living systems, it is one of several short-chain fatty acids involved in energy metabolism and gut ecology.

Uses: Sodium and calcium propionate are widely used as food preservatives to inhibit mold and bacteria in bread, baked goods, dairy products, and some processed foods. They also function as feed additives and serve as chemical intermediates in organic synthesis, including the preparation of esters and other propionate derivatives.

Safety and handling: Propanoate salts are generally recognized as safe for approved uses in foods. Concentrated propionic acid and some propionate salts can be irritants to skin, eyes, and the respiratory tract, so proper handling is advised in industrial settings.