METHOD OF PREPARING LACTAM Russian patent published in 2001 - IPC

FIELD: preparation of aliphatic lactams from dinitriles. SUBSTANCE: method comprises two stages. In first stage semihydrogenation of dinitrile is carried out with hydrogen with heterogeneous catalyst to corresponding aminonitrile, in second stage hydrolysis with water is carried out in vapor phase with or without catalyst and simultaneous cyclization to lactam. Intermediate aminonitrile is purified from water and/or solvent and organic impurities by distillation at lower pressure. In hydrolysis stage, catalyst includes zeolite, silicate or other molecular acid-or amphoteric-type sieves, or metal phosphate of general formula: (PO₄)_nH₄(Imp)_p wherein Imp is impregnating compound based on alkali or alkali-earth metal, and yield and purity of the final product in thus increased. EFFECT: more efficient preparation method. 15 cl, 2 ex