Patent ID: 6974880

Claim:
A process for the manufacture of a diisocyanate of the formula (I) OCN—R—NCO (l), wherein R represents a (cyclo-)aliphatic or aromatic hydrocarbon group having up to 15 carbon atoms, provided that at least two carbon atoms are arranged between the two NCO groups, by phosgenation of the corresponding vaporous diamine of the formula (II) H 2 N—R′—NH 2 (II), wherein R′represents a (cyclo-)aliphatic or aromatic hydrocarbon group having up to 15, provided that at least two carbon atoms are arranged between the two amino groups, in which the vaporous diamine, optionally rarefied with an inert gas or with the vapors of an inert solvent, and phosgene are heated separately to temperatures of from about 2000° C. to about 600° C., mixed and reacted in a tube reactor having a number n≧2 of nozzles directed parallel to the axis of the tube reactor arranged in the tube reactor, the diamine-containing stream being fed into the tube reactor through the n nozzles and the phosgene stream being fed into the tube reactor through remaining free space.