Acetic Acid

CH3COOH

IUPAC name: Acetic acid - Ethanoic acid.
Other names: -
CAS Number: 64-19-7

Acetic acid is one of the simplest carboxylic acids (the second after formic acid); it is an organic compound in the class of aliphatic carboxylic acids; it is a colourless liquid with a pungent smell. It has been known since ancient times as a component of vinegar, where it is formed by fermentation of ethanol. In a pure state it is called glacial acetic acid because it becomes a transparent crystalline solid below 17 C. 
Liquid acetic acid is a protic hydrophilic (polar) solvent, similar to ethanol and water. With its moderate dielectric constant of 6.2, it dissolves not only polar compounds such as inorganic salts and sugars, but also non-polar compounds such as oils, and chemical elements like sulphur and iodine. It blends readily with other polar and non-polar solvents such as water, chloroform, and hexane. Because of these dissolution and miscibility properties, acetic acid is a widely used product in the chemical industry. Acetic acid is corrosive and its vapours induce irritation of the eyes, inflammation of the respiratory tract, and congestion of the lungs, but it is a weak acid from a chemical point of view because of its limited capacity to dissociate in aqueous solution.

Manufacture

Concentrated acetic acid is prepared on an industrial scale utilising various processes, among which are the reaction between methanol and carbon monoxide in the presence of a catalyst (carbonylation of methanol: Monsanto process) and the oxidation of acetaldehyde.

Principal uses

  • production of polyethylene terephthalate, utilised mainly to make plastic bottles for soft drinks;
  • production of cellulose acetate, utilised mainly for photographic films;
  • production of polyvinyl acetate for wood glues;
  • production of synthetic fibres and textiles (e.g. rayon.)

It is also used in these sectors:

  • production of solvents for paints;
  • production of pharmaceuticals;
  • food industry.