Patent Number: 6,307,096

Title: Method for making aliphatic diisocyanates

Abstract: A method for making an aliphatic diisocyanate by (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.

Inventors: Sommer; Alexa B. (Pittsburgh, PA), Wittig; Mary Ann (Carnegie, PA), Hortelano; Edwin Ray (Charleston, SC), Yeske; Philip E. (Cologne, DE), Ciebien; Jane F. (Charleston, SC)

Assignee: Bayer Corporation

International Classification: C07C 263/00 (20060101); C07C 263/10 (20060101); C07C 263/20 (20060101); C07C 265/14 (20060101); C07C 265/00 (20060101); C07C 263/00 ()

Expiration Date: 10/23/2018