Method for purifying lactams

摘要

PCT No. PCT/FR97/01426 Sec. 371 Date Apr. 23, 1999 Sec. 102(e) Date Apr. 23, 1999 PCT Filed Jul. 31, 1997 PCT Pub. No. WO98/05636 PCT Pub. Date Feb. 12, 1998A method for purifying lactams by liquid-liquid extraction and/or processing with an ion exchange resin is disclosed. The method is useful for purifying lactams produced by the cyclising vapour-phase hydrolysis of an aliphatic aminonitrile, and comprises removing the major part of the ammonia before subjecting the lactam to liquid-liquid extraction by means of a solvent including an acidic solvent and/or contacting said lactam with a cation exchange resin. In most applications of the lactam, it is preferable to carry out a hydrogenation step on the compounds of the lactam solution comprising unsaturations, prior to or in addition to the liquid-liquid extraction step and/or the acidic resin contact step. The purification method may also include an oxidation step in addition to or instead of the hydrogenation step. Said method is preferably combined with a distillation step in the presence of a base.