Process for the preparation of nitro-substituted arylamines

A process for the preparation of a compound of the formula ##STR7## in which Ar denotes a monocyclic or polycyclic, aromatic C.sub.4 -C.sub.16 radical, which can also contain 1 to 2 heteroatoms selected from the group consisting of N, O and S,

• R denotes hydrogen, C.sub.1 -C.sub.8 -alkyl, C.sub.2 -C.sub.8 -alkenyl, C.sub.3 -C.sub.7 -cycloalkyl and C.sub.6 -C.sub.14 -aryl, where these substituents are optionally monosubstituted to trisubstituted by halogenated, C.sub.1 -C.sub.4 -alkyl, amino and/or C.sub.1 -C.sub.4 -alkoxy,
• X denotes halogen, cyano, C.sub.1 -C.sub.4 -alkyl, halogenated C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, halogenated C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylmercapto, halogenated C.sub.1 -C.sub.4 -alkylmercapto, C.sub.1 -C.sub.4 -alkylsulfonyl or nitro,
• n denotes zero, 1, 2 or 3 where for n>1 the substituents X can be different,
• which comprises reacting a nitroaromatic compound of the formula ##STR8## in which X, Ar and n have the meanings given above, with a urea of the formula ##STR9## in which the two substituents R are identical or different and have the meaning given above and
• Y represents oxygen or sulfur
• in the presence of an inorganic or organic base and oxygen, in a polar solvent wherein 0.5 to 10 mol of the urea of formula (III) is used per mol of the nitroaromatic of formula (II) and 1 to 10 equivalents of base are present and at a temperature between -35.degree. C. and 120.degree. C.