 an aniline of the formula XX 
with a dialkyl disulfide of the formula VII
R2xe2x80x94Sxe2x80x94Sxe2x80x94R2xe2x80x83xe2x80x83VII
in the presence of a catalyst. Preferred catalysts are copper powder, in particular copper powder having a particle size of below 70 xcexcm, or elemental copper in another form, such as, for example, turnings, wire, granules, pellets or rods.
In the compounds of the formula XIX and XX, Rx is any radical which is chemically inert under the chosen reaction conditions during the reaction with compounds of the formula VII. In this sense, suitable Rx groups are, for example: hydrogen, alkyl, aloalkyl, halogen, cyano, nitro, alkoxy, haloalkoxy, alkylthio or heterocyclic radicals as mentioned at the outset in the definition of R6. A heterocyclic radical is, in particular, an unsubstituted or alkyl-substituted 5-membered heterocyclic saturated, partially saturated or aromatic ring from the group of the isoxazolines, isoxazoles, thiazolines, thiazoles, oxazoles and pyrazoles. The compounds of the formula XIX and XX may carry one or more, preferably one, two or three, substituents Rx, which may be identical or different.
Rx is preferably a C1-C6-alkyl group, for example methyl, ethyl or propyl. m is preferably the number 1 or 2. If m is the number 1, Rx is preferably ortho or meta to the group xe2x80x94Sxe2x80x94R2 (in the case of compounds XIX) or to the amino group (in the case of the compounds XX). If m is the number 2, the second radical Rx is preferably ortho and meta to the group xe2x80x94Sxe2x80x94R2 or to the amino group.
Thioethers of the formula XIX are useful intermediates for preparing active compounds in the chemical industry, for example for preparing crop protection agents (for example WO 96/11906; WO 98/31676) or for preparing medicaments. A process which is frequently used for introducing alkylthio functions is the exchange of a halogen (EP 0 711 754). However, the process described in this publication has the disadvantage that it is limited to aromatic compounds which are subst