Process for the preparation of urea derivatives and catalyst system.

摘要

The invention relates to a process for the preparation of urea derivatives of the general formula <CHEM> wherein R is an alkyl group and X is a halogen atom, an alkyl-, alkoxy-, aryloxy-, cyano-, ester- or trifluoromethyl group and n is from 0 to 5, which comprises reacting an aromatic nitro compound of the general formula <CHEM> wherein X and n are as defined above with carbon monoxide and an amine HNR2 wherein R is an alkyl group, in the presence of a catalyst system comprising (a) a group VIII noble metal or a compound thereof, (b) a bidentate ligand and (c) an acid having a pKa of more than 2 or a transition metal salt of said acid. t