Patent ID: 6248926
Filing Date: 2001-06-19
Classification: C07C

Abstract:
A process for separating HMD from a feed mixture comprising HMD, ACN and PRI, said process comprising:a) introducing the feed mixture into a distillation column at a feed point located therein;b) withdrawing from a distillate withdrawal point, located above the feed point, a distillate which comprises HMD, and which further comprises at most a minor portion of the PRI which is fed to the column in the feed mixture, the locations of the feed point and the distillate withdrawal point defining a rectifying zone of the column having a length which extends between the feed point and the distillate withdrawal point and a temperature which varies along the length; andc) withdrawing from a bottoms withdrawal point, located below the feed point, a bottoms which comprises ACN, substantially free of HMD, and which further comprises a major portion of the PRI fed to the column in the feed mixture;provided that the process is carried out while the temperature in the rectifying zone of the column varies sigmoidally along the length of the rectifying zone.