The chemical compound acetic acid (CH3COOH or or C2H4O2), more properly ethanoic acid, is a colourless liquid that melts at 16.6°C and boils at 117.9°C, it is a stable carboxylic acid. It is an acid and can lose one proton in solution, turning into the acetate ion CH3COO-.
In a weak aqueous solution it is known as vinegar, although natural vinegars typically contain additional components. It is used as a food additive, as a photographic chemical, in the manufacture of plastics such as polyethylene terephthalate (PET, packaging) or cellulose acetate, in the production of vinyl acetate (paints and adhesives) and solvent esters.
It is manufactured by liquid-phase oxidation of n-butane or recovered during the production of cellulose acetate and polyvinyl alcohol.
Since anhydrous acetic acid is solid at 16.6°C it is sometimes called glacial acetic acid.