Patent ID: 6887352
Filing Date: 2005-05-03
Classification: B01D,C07C

Abstract:
1. A method for recovering hexamethylene diamine (HMD) from a mixture comprising HMD, 6-aminocapronitrile (ACN), tetrahydroazepine (THA), and adiponitrile (ADN) comprising: introducing the mixture into a first distillation column; separating as a group the HMD, ACN and at least a portion of the THA from the ADN, wherein the HMD, ACN and at least a portion of the THA is removed as distillate and wherein the first distillation column in operated at a temperature and pressure to minimize isomerization of the ADN into 2-cyanocyclopentylideneimine (CPI); introducing a composition comprising the distillate of the first distillation column into a subsequent distillation column; and separating the HMD from the ACN and THA, wherein the distillate from the subsequent distillation column comprises HMD and the bottoms from the subsequent distillation column comprises the ACN and THA.