Patent ID: 8362154

Claim:
A process for the molecular weight degradation of a nitrile rubber comprising a metathesis reaction of a nitrile rubber in the presence of a catalyst of the general formula (I), where M is ruthenium or osmium, X 1 and X 2 are identical or different anionic ligands, Z 1 and Z 2 are identical or different and neutral electron donor ligands, R 3 and R 4 are identical or different and hydrogen or a substituent selected from the group consisting of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, carboxylate, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, dialkylamino, alkylthio, arylthio, alkylsulphonyl and alkylsulphinyl radical, each of which may optionally be substituted by one or more substituents, and L is a ligand.