acetic acid (əsç'tĭk) , CH3CO2H, colorless liquid that has a characteristic pungent odor, boils at 118°C, and is miscible with water in all proportions; it is a weak organic carboxylic acid (see carboxyl group). Glacial acetic acid is concentrated, 99.5% pure acetic acid; it solidifies at about 17°C to a crystalline mass resembling ice. Acetic acid is the major acid in vinegar; as such, it is widely used as a food preservative and condiment. For industrial use concentrated acetic acid is prepared from the oxidation of acetaldehyde. Acetic acid is also a product in the destructive distillation of wood. It reacts with other chemicals to form numerous compounds of commercial importance. These include cellulose acetate, used in making acetate rayon, nonflammable motion-picture film, lacquers, and plastics; various inorganic salts, e.g., lead, potassium, and copper acetates; and amyl, butyl, ethyl, methyl, and propyl acetates, which are used as solvents, chiefly in certain quick-drying lacquers and cements. Amyl acetate is sometimes called banana oil because it has a characteristic banana odor.
There is acetic acid in vinegar but there is no vinegar in acetic acid. Vinegar is made from fruit and alcohol. Glacial acetic acid is made from a petroleum based chemical and has none of the trace minerals found in vinegar. There is an attempt to continue to use it by some people because it is far cheaper than real vinegar.