Abstract: This invention is a method of purifying crude caprolactam. The improved method comprises taking a portion of a process stream of crude caprolactam having low boiling impurities and distilling the stream in the presence of water by fractional distillation into an overhead containing water and low boiling impurities and bottoms of caprolactam having improved purity and low water content.The improvement also comprises taking a low water content stream of crude caprolactam having low boiling impurities and adding water to the stream and distilling the stream by fractional distillation as described above.

Abstract: This invention is the method to recover caprolactam from a concentrated nylon 6 chip wash water containing water, cyclic oligomer, and caprolactam. The method comprises feeding the concentrated wash water to a wiped-film evaporator operated at a temperature of from about 200.degree. C. to 300.degree. C. and a pressure from about 10 to about 250 Torr, thereby separating the wash water into (a) an overhead stream of water and caprolactam and (b) a bottom stream of caprolactam and cyclic oligomers, then recovering the caprolactam from the overhead stream. The caprolactam in the bottom stream can also be recovered, and the cyclic oligomers depolymerized to caprolactam for recovery.