Ammonia → Caprolactam

Participants

Reaction Steps

ε-Caprolactam is a precursor for the preparation of Nylon-6. Nylon-6 was first made in 1899 by heating 6-aminohexanoic acid. Commercially feasible synthesis of Nylon-6 from ε-caprolactam was discovered by Paul Schlack at I. G. Farbenindustrie in 1938. Currently, approximately 95% of the world's ε-caprolactam is produced from cyclohexanone oxime via the Beckmann rearrangement. The starting material for cyclohexanone can be cyclohexane, phenol, or benzene. Through a series of reductions and/or oxidations, cyclohexanone is formed. The latter is then reacted with a hydroxylamine salt usually the sulfate, to form the oxime and ammonium sulfate. The oxime is rearranged in concentrated sulfuric acid, and the resulting lactam sulfate salt is neutralized with ammonia to form ε-caprolactam and additional ammonium sulfate. Subsequently, pure ε-caprolactam is obtained through numerous separation and purification steps. The current process is extremely capital intensive and generates large quantities of waste.

Provenance & Evidence