METHOD OF SYNTHESIS OF CAPROLACTAM Russian patent published in 2000 - IPC

FIELD: chemical technology, organic chemistry. SUBSTANCE: invention relates to synthesis of caprolactam used for polymeric compounds producing. Caprolactam is produced by thermic treatment of 6-aminocaproic acid nitrile in the presence of heterogeneous catalysts and water. Low- or high-boiling alcohol is added to reaction mixture and heated into reactor (A) to obtain the mixture. The latter is distilled to obtain the "head" fraction, aminocaproic acid esters, caprolactam and vat residue. If the mixture (I) has ammonia then it is removed before distillation. The "head" fraction is recovered into reactor (A) from the distillation stage adding alcohol and/or water to its if necessary or "head" fraction is fed into the next reactor (B) and mixed if necessary with vat residue obtained at the same distillation stage and adding if necessary alcohol and/or water and the parent 6-aminocaproic acid nitrile also. Product from reactor (B) is fed to the distillation stage as for product from reactor (A) and caprolactam, vat residue and "head" fraction are obtained, respectively. Also, vat residue obtained at distillation stage after reactor (A) is proposed to be treated by other 4 variants: 1) feeding to processing into reactor (A); 2) addition of water and/or alcohol in its and processing into reactor (C); 3) addition of water and processing into reactor (D) without catalyst; 4) addition of water and processing into reactor (E). All reactors (A-E) are connected with independent stages of distillation. Temperature and pressure values in reactors are 100-320 C and 0.1-50 MPa, respectively. EFFECT: high yield of product, high selectivity of process, absence of rapid inactivation of catalyst, decreased wastes. 7 cl, 3 ex