Patent ID: 7468119
Filing Date: 2008-12-23
Classification: C07C

Abstract:
1. A method of separating a feed mixture comprising 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD), comprising: introducing a feed mixture comprising ACN, tetrahydroazepine (THA), and HMD into a refined distillation column; operating the refined distillation column under conditions such that: a refined column distillate comprising HMD is withdrawn from the refined distillation column; and a refined column tails comprising ACN, THA and dimers of ACN and HMD is withdrawn from the refined distillation column; introducing the refined column tails into a dimer removal column; and operating the dimer removal column under conditions such that: a dimer removal column distillate comprising ACN and THA is withdrawn from the dimer removal column; and a dimer removal column tails comprising dimers of ACN and HMD is withdrawn from the dimer removal column; wherein the levels of dimers in the refined column tails substantially exceeds the level of dimers in the dimer removal column distillate.