| abstract |
Impurities are removed by allowing the crude lactams at temp. 2-80 C, preferably at 5-30 C (above the m.pt. of the lactam), or the fresh, crude lactam distillate leaving the column to pass under exclusion of air, through pipes filled up with oxides of elements of gps. IIB, IIA, IVB, VA, IVA, VIB, or VIIIB, or with elementary metals of groups VIIIB of the periodical system and subsequently separating the pure lactams, and regenerating the purifying agents. |