Novel catalyst systems and a process for reacting chemical compounds in the presence of said catalyst systems

Abstract

New catalyst systems for metathesis reactions, in particular for the metathesis of nitrile rubber, are provided.

Description

FIELD OF THE INVENTION [0001] The present invention relates to novel catalyst systems and a method for reacting chemical compounds by subjecting such compounds to a metathesis reaction in the presence of said catalyst systems. BACKGROUND OF THE INVENTION [0002] Metathesis reactions are widely used for chemical syntheses, e.g. in the form of ring-closing metatheses (RCM), cross-metatheses (CM) or ring-opening metatheses (ROMP). Metathesis reactions are employed, for example, for the synthesis of olefins, for the depolymerization of unsaturated polymers and for the synthesis of telechelic polymers. [0003] Metathesis catalysts are known, inter alia, from WO-A-96 / 04289 and WO-A-97 / 06185. They have the following in-principle structure: where M is osmium or ruthenium, the radicals R are identical or different organic radicals having a wide range of structural variation, X1 and X2 are anionic ligands and L are uncharged electron donors. The customary term “anionic ligands” is used in the...

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Benefits of technology

[0027] It has surprisingly been found that the activity of metathesis catalysts can be increased when they are used in combination with salts other than copper salts.

Problems solved by technology

The processability of HNBR is subject to severe restrictions as a result of the relatively high Mooney viscosity.

However, this thermomechanical degradation has the disadvantage that functional groups such as hydroxyl, keto, carboxyl and ester groups, are incorporated into the molecule as a result of partial oxidation and, in addition, the microstructure of the polymer is substantially altered.

The preparation of HNBR having low molar masses corresponding to a Mooney viscosity (ML 1+4 at 100° C.) in the range below 55 or a number average molecular weight of about Mn<200 000 g / mol was for a long time not possible by means of established production processes since, firstly, a step increase in the Mooney viscosity occurs in the hydrogenation of NBR and, secondly, the molar mass of the NBR feedstock used for the hydrogenation cannot be reduced at will since otherwise the work-up can no longer be carried out in the industrial plants available because the product is too sticky.

However, the amounts of Grubbs (I) catalyst employed for carrying out the metathesis are large.

However, the amounts of ruthenium necessary for this efficient metathetic degradation are still relatively high.

However, this increase in activity due to copper salts in the abovementioned ring-closing metathesis cannot be carried over to any desired other types of metathesis reactions.

Our studies have unexpectedly shown that although the addition of copper salts leads to an initial acceleration of the metathesis reaction in the metathetic degradation of nitrile rubbers, a significant decrease in the efficiency of the metathesis is observed: the molecular weights which can ultimately be achieved for the degraded nitrile rubbers are substantially higher than when the metathesis reaction is carried out in the presence of the same catalyst but in the absence of the copper salts.

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