Patent ID: 7371891
Filing Date: 2008-05-13
Classification: C07C

Abstract:
1. A multistage process for continuously preparing a cycloaliphatic diisocyanate, by reacting a cycloaliphatic diamine with a carbonic acid derivative and an alcohol to give a cycloaliphatic diurethane and subsequently thermally cleaving the cycloaliphatic diurethane to give a cycloaliphatic diisocyanate, which comprises: performing the formation of the cycloaliphatic diurethane in two stages; cleaving the cycloaliphatic diurethane freed of low and medium boilers to release the desired cycloaliphatic diisocyanate; continuously discharging a portion of the cleavage residue from the cleavage apparatus; reurethanizing the discharge with an alcohol; removing the high boiler components therefrom; and recycling the reurethanized stream into the process.