Basf Aktiengesellschaft

Gerard Van Wauwe

Gerald Neubauer

Hugo Fuchs

Uwe Brand

Klaus Kartte

Emile De Decker

Jozef Oostvogels

Josef Beullens

Caprolactam is prepared in a process comprising

Preparation of caprolactam from cyclohexanone oxime by Beckmann

A process for obtaining coarsely crystalline pure ammonium sulfate from reaction mixtures which have been obtained by Beckmann rearrangement of cyclohexanone-oxime with sulfuric acid or oleum, by neutralizing the mixtures with ammonia at an elevated temperature, with the addition of recycled ammonium sulfate mother liquor, the concentration being so chosen that during the neutralization no solid ammonium sulfate precipitates, separating the crude caprolactam from the ammonium sulfate solution, crystallizing ammonium sulfate by evaporating the ammonium sulfate solution under reduced pressure, separating off the crystallized ammonium sulfate and recycling the mother liquor to the neutralization stage. The neutralization is carried out at from 80.degree. to 115.degree. C. under autogenous pressure and the ammonium sulfate solution obtained after separating off the crude lactam is evaporated under a pressure of from 200 to 600 mm Hg while cooling to from 72.degree. to 101.degree. C.

Process for obtaining coarsely crystalline pure ammonium sulfate

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Edegem, Belgium

Gerard Van Wauwe