Patent ID: 6307096
Filing Date: 2001-10-23
Classification: C07C,Y02P

Abstract:
A method for making an aliphatic diisocyanate comprising the steps of:(a) phosgenating an aliphatic diamine in the presence of an inert solvent or gas to form a crude reaction mixture;(b) distilling the crude reaction mixture to form an aliphatic diisocyanate production stream and an aliphatic diisocyanate waste stream;(c) introducing the aliphatic diisocyanate waste stream to a chamber and placing the waste stream under supercritical fluid conditions sufficient to dissolve an appreciable amount of the aliphatic diisocyanate component in the supercritical fluid;(d) separating the dissolved aliphatic diisocyanate component from the waste stream, wherein the remaining waste stream is a supercritically-purged aliphatic diisocyanate waste stream;(e) lowering the pressure sufficiently to precipitate the aliphatic diisocyanate component.