公开(公告)号：DE2651195A1

公开(公告)日：1978-05-18

申请号：DE2651195

申请日：1976-11-10

Applicant: BASF AG

Inventor： NEUBAUER GERALD DIPL CHEM DR ,  WAUW GERARD VAN ,  BEULLENS JOSEF

IPC: C07D201/16 ,  C01C1/242 ,  C01C1/248 ,  C01C1/24

Abstract: Recovery of large crystals of pure ammonium sulphate (I) from reaction mixts. obtd. by Beckmann rearrangement of cyclohexanone oxime (II) in H2SO4 or oleum to give caprolactam (III) comprises first neutralising the mixt. with NH3 at autogenous pressure and 80-125 degrees C. The crude lactam is sepd. and the residual soln. evapd. at 200-600 mm Hg, with cooling to 72-101 degrees C to crystallise (I). The crystals formed are sepd. and the mother liquor recycled to neutralisation. The concn. of (I) in the recycled mother liquor is insufficient to cause crystallisation during neutralisation. Pref. neutralisation is to pH 4.5-5, and the vapours from evaporation can be condensed and used to dilute the mother liquor. Alternatively they are used to concentrate either the hydroxylammonium sulphate solns. used to make (II) from cyclohexanone, or the (I) solns. obtd. by neutralising the oximation reaction mixt. (I) is a fertiliser. It is obtd. as larger crystals than in other processes, and these have lower moisture and esp. caprolactam contents. Utilisation of steam from the evaporator improves heat economy.