Multistep process to prepare cycloaliphatic diisocyanates, useful to prepare e.g. urethane, comprises reacting cycloaliphatic diamine with carbonic acid derivative and alcohol and thermally cleaving the obtained cycloaliphatic diurethane

摘要

Multistep process for continuously preparing cycloaliphatic diisocyanates, comprises reacting a cycloaliphatic diamine with a carbonic acid derivative and an alcohol to produce a cycloaliphatic diurethane, separating the cycloaliphatic diurethane from low, middle and high boilers, and then thermally cleaving the cycloaliphatic diurethane to produce a cycloaliphatic diisocyanate, and continuously discharging a portion of the cleavage residue and reurethanizing the portion with an alcohol, and recycling the reurethanization product directly into the low-boiler separation. Multistep process for continuously preparing cycloaliphatic diisocyanates, comprises reacting a cycloaliphatic diamine with a carbonic acid derivative and an alcohol to produce a cycloaliphatic diurethane, separating the cycloaliphatic diurethane from low, middle and high boilers, and then thermally cleaving the cycloaliphatic diurethane to produce a cycloaliphatic diisocyanate, and continuously discharging a portion of the cleavage residue and reurethanizing the portion with an alcohol, and recycling the reurethanization product directly into the low-boiler separation; where the unconditioned urea and/or unconditioned urea produced from urea material are used equivalently.