Process for degrading nitrile rubbers in the presence of catalysts having an increased activity
View Patent ↗A process of degrading nitrile rubbers comprises subjecting them to a metathesis reaction in the presence of specific catalysts with increased activity.
1. A process for degrading a nitrile rubber comprising subjecting the nitrile rubber to a metathesis reaction in the presence of a catalyst of general formula (IV),
wherein:
M is ruthenium,
X 1 and X 2 are both chlorine,
R 1 is an isopropyl radical,
R 2 , R 3 , R 4 , R 5 are all hydrogen, and
L is a substituted or unsubstituted imidazolidine radical of the formula (IIa) or (IIb),
where
R 8 , R 9 , R 10 , R 11 are identical or different and are each hydrogen, straight-chain or branched C 1 -C 30 -alkyl, C 3 -C 20 -cycloakyl, C 2 -C 20 -alkenyl, C 2 -C 20 -alkynyl, C 6 -C 24 -aryl, C 1 -C 20 -carboxylate, C 1 -C 20 -alkoxy, C 2 -C 20 -alkenyloxy, C 2 -C 20 -alkynyloxy, C 6 -C 24 -aryloxy, C 2 -C 20 -alkoxycarbonyl, C 1 -C 20 -alkylthio, C 6 -C 24 -arylthio, C 1 -C 20 -alkylsulphonyl, C 1 -C 20 -alkylsulphonate, C 6 -C 24 -arylsulphonate or C 1 -C 20 -alkylsulphinyl.
2. A process for degrading a nitrile rubber comprising subjecting the nitrile to a metathesis reaction in the presence of a catalyst of the formula (V), (VI), (VII), (VIII), (IX), (X), (XI), or (XII)
where Mes is in each case a 2,4,6-trimethylphenyl radical.
3. A process for degrading a nitrile rubber comprising subjecting the nitrile rubber to a metathesis reaction in the presence of catalysts of the general formula (XIII),
where
M, L, X 1 , X 2 , R 1 and R 6 have the meanings given for the general formula (I), the radicals R 12 are identical or different and have the meanings given for the radicals R 2 , R 3 , R 4 and R 5 in the general formula (I), with the exception of hydrogen, and
n is 0, 1, 2 or 3.
4. A process for degrading a nitrile rubber comprising subjecting the nitrile rubber to a metathesis reaction in the presence of catalyst of the formula (XIV) or (XV)
5. A process for degrading a nitrile rubber comprising subjecting nitrile rubber to a metathesis reaction in the presence of a catalyst of the general formula (XVIII),
where the symbol
●
represents a support.
6. A process for degrading a nitrile rubber comprising subjecting the nitrile rubber to a metathesis reaction in the presence of a catalyst of the general formula (XVIII),
where the symbol
●
represents a support consisting of a poly(styrene-divinylbenzene) copolymer (PS-DVB).