Process for the preparation of (cyclo)aliphatic diisocyanates

摘要

The present invention relates to a process for the preparation of diisocyanates corresponding to the formula OCN-R-NCO wherein R denotes a (cyclo)aliphatic hydrocarbon group with up to 15 carbon atoms by phosgenation of the corresponding diamines represented by the formula H2N-R-NH2 in the gas phase, characterized in that (a) the diamines in vapor form, optionally diluted with an inert gas or with the vapors of an inert solvent, and phosgene are separately heated to temperatures of about 200 DEG to 600 DEG C. and continuously reacted together in a cylindrical reaction chamber which is free from moving parts and heated to about 200 DEG to 600 DEG C., while a turbulent flow is maintained in the reaction chamber. (b) the gas mixture continuously leaving the reaction chamber is passed through an inert solvent for the diisocyanate which is maintained at a temperature above the decomposition temperature of the carbamic acid chloride corresponding to the diamine, and (c) the diisocyanate which is dissolved in the inert solvent is purified by distillation.