Adipiinhappe

Adipiinhappe, commonly known in English as adipic acid, is hexanedioic acid, a colorless, crystalline organic compound with the chemical formula C6H10O4. It is a dicarboxylic acid consisting of a six-carbon aliphatic chain with carboxyl groups at both ends. Adipic acid is a staple industrial chemical and a key intermediate in polymer production.

Industrial production and sources

Adipic acid is produced primarily by catalytic oxidation of cyclohexanone and cyclohexanol, together often referred to as KA oil, using air as the oxidant. This oxidation process takes place under high temperature and pressure in the presence of metal catalysts and yields adipic acid along with byproducts, including nitrous oxide, a greenhouse gas. Efforts in the industry focus on increasing yield and reducing environmental impact. Alternative routes exist, including oxidation of cyclohexene, but the KA oil pathway remains the dominant source for commercial adipic acid.

Properties

Adipic acid is a solid at room temperature with a melting point near 152–153°C. It has limited solubility in cold water but dissolves more readily in hot water and in several polar organic solvents. The compound is stable under ordinary storage conditions but should be protected from excessive heat, moisture, and strong bases.

Uses and applications

The primary use of adipic acid is as a precursor to nylon-6,6, formed by condensation with hexamethylenediamine to produce polyamide 6,6. It is also employed to make adipate esters used as plasticizers, as well as in resins, coatings, and specialty polymers. In some applications, adipic acid derivatives serve in polyurethane production and as crosslinking agents.

Safety and environmental aspects

Adipic acid is of relatively low acute toxicity, but it can irritate skin, eyes, and the respiratory tract. Handling requires standard chemical safety practices. Industrial production contributes to nitrous oxide emissions, which are managed through emissions controls and process improvements to reduce environmental impact.