Two-Phase Beckmann Rearrangement of Cyclohexanone Oxime under Milder Conditions in Cyclohexane

An innovative green process of producing ε-caprolactam (CPL) was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a second part of the new process, two-phase (liquid-liquid) Beckmann rearrangement of cyclohexanone oxime to caprolactam was carried out using solution of oxime-cyclohexane as reactant instead of melting oxime in conventional route. The experimental results indicated that a relatively high yield of CPL can be achieved with much less oleum under milder reaction conditions in comparison with conventional technology. Furthermore, preliminary work on the quality of CPL, characterized by D value, was also performed. It was found that molar ratio of acid to oxime had a great impact on D value while the influences of other parameters were less important.