ChEBI: A short-chain saturated fatty acid comprising ethane attached to the carbon of a carboxy group.
Propionic acid, CH3CH2COOH, also known as propanoic acid and methylacetic acid, is a clear, colorless liquid that boils at 140°C (284 OF). It has a pungent odor and is soluble in water and alcohol. Propionic acid is used in nickel electroplating solutions,perfumes, artificial flavors, pharmaceuticals, and manufacturing propionates.
Propionic acid reacts as an acid to neutralize bases in exothermic reactions. Burns when exposed to heat, flame or oxidizers. When heated to decomposition emits acrid smoke and irritating fumes [Lewis, 3rd ed., 1993, p. 1090].
Dry the acid with Na2SO4 or by fractional distillation, then redistil after refluxing with a few crystals of KMnO4. An alternative purification uses conversion to the ethyl ester, fractional distillation and hydrolysis. [Bradbury J Am Chem Soc 74 2709 1952.] Propionic acid can also be heated for 0.5hour with an amount of benzoic anhydride equivalent to the amount of water present (in the presence of CrO3 as catalyst), followed by fractional distillation. [Cham & Israel J Chem Soc 196 1960, Beilstein 2 IV 695.]
Used as esterifying agent.
Air & Water Reactions
Dilution with water causes release of heat.
A clear oily aqueous liquid with a pungent rancid odor. Burns skin and the vapors irritate mucous membranes. Corrosive to most metals and tissue. Density 8.3 lb / gal.
Flammable/combustible material. May be ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.
May cause toxic effects if inhaled or ingested/swallowed. Contact with substance may cause severe burns to skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.