Synthesis of ε-caprolactam precursors through the N-hydroxyphthalimide-catalyzed aerobic oxidation of K/A-oil

Abstract

A methodology for the preparation of ε-caprolactam (CL) precursors like 1,1′-peroxydicyclohexylamine (PDHA) and/or cyclohexanone oxime from K/A-oil (a mixture of cyclohexanone and cyclohexanol) has been established by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, the aerobic oxidation of K/A-oil catalyzed by NHPI followed by treatment with ammonia afforded CL precursors in high selectivities.