Caprolactone

Caprolactone is a cyclic ester, known as a lactone, with a ring size of seven. It is a clear colorless liquid that is miscible with most organic solvents except aliphatic hydrocarbons. It reacts slowly with water to form 6-hydroxyhexanoic acid.

Caprolactone is prepared industrially by Baeyer-Villiger oxidation of cyclohexanone with peracetic acid.

The lactone ring is easily opened with nucleophiles including alcohols and water. Caprolactone is a monomer used in the manufacture of various polymers including polycaprolactone. It is also used in synthetic fibers, polyurethane elastomers, plastics, adhesive fabrics, and coatings.

The are three manufacturers in the world, BASF in the USA, Daicel in Japan and the largest Solvay in the UK.

Caprolactone is known to cause severe eye irritation. Exposure may result in corneal injury.