propanoate

Propanoate, also known as propionate, denotes the conjugate base of propionic acid (propanoic acid). It occurs as salts of various cations, such as sodium propanoate, potassium propanoate, and calcium propanoate, and as esters in which the propionic acid moiety is linked to an alcohol.

The propanoate anion has the formula C2H5COO−. Propionic acid has a pKa of about 4.87, so propanoate is a weak base and participates in acid–base equilibria in water. Salts of propanoic acid are typically water-soluble. Esters of propanoic acid (propanoates) are formed by reaction with alcohols and are commonly used as flavor and fragrance esters, including ethyl propanoate and propyl propanoate.

Preparation and reactions: Propanoate salts are produced by neutralization of propionic acid with bases such as NaOH, KOH, or Ca(OH)2. Propanoate esters are prepared by esterification of propionic acid with alcohols under acid catalysis or via transesterification.

Uses: Sodium, potassium, and calcium propanoates are widely used as food preservatives to inhibit mold growth in bread and other baked goods. They also serve as intermediates in organic synthesis and as components in animal feeds.

Safety: Propionic acid is an irritant; its salts are less hazardous but can cause irritation in high concentrations. Standard chemical-handling precautions apply.