KR101162394B1 - Process for the preparation of low molecular weight nitrile rubber - Google Patents

Abstract

Optionally hydrogenated nitrile rubber polymers having a lower molecular weight and narrower molecular weight distribution than those known in the art can be prepared after metathesis of nitrile butadiene rubber, optionally by hydrogenation. The method comprises the steps of: a) reacting a nitrile rubber in the presence of at least one compound that is a ruthenium or osmium-based indenylidene complex; And optionally b) hydrogenating the resulting lower molecular weight nitrile rubber using standard techniques known in the art. Optionally hydrogenated nitrile rubbers with lower molecular weight and narrower molecular weight distribution have very good heat resistance, excellent ozone and chemical resistance, and excellent oil resistance. It is used in the automotive, oil, electrical, mechanical engineering and shipbuilding industries.

Low molecular weight nitrile rubber, hydrogenated nitrile rubber, metathesis reaction, hydrogenation reaction

Description

Process for producing low molecular weight nitrile rubber {PROCESS FOR THE PREPARATION OF LOW MOLECULAR WEIGHT NITRILE RUBBER}

The present invention relates to a process for producing optionally hydrogenated nitrile rubber polymers having lower molecular weight and narrower molecular weight distribution than those known in the art.

Hydrogenated nitrile rubbers (HNBR) made by selective hydrogenation of acrylonitrile-butadiene rubbers (nitrile rubbers; NBR, copolymers comprising at least one conjugated diene, at least one unsaturated nitrile and any additional comonomer) are very good It is a special rubber having heat resistance, excellent ozone resistance and chemical resistance, and excellent oil resistance. With regard to the high level of mechanical properties (particularly high wear resistance) of this rubber, NBR and HNBR are particularly suitable for automobiles (sealing materials, hoses, bearing pads), oils (stators, well head sealants, valve plates), electrical (cables). It is not surprising that they are used extensively in the cladding), mechanical engineering (wheel, roller) and shipbuilding (pipe seals, couplings) industries.

Commercially available NBR and HNBR have a Mooney viscosity in the range of 55 to 105, a molecular weight in the range of 200,000 to 500,000 g / mol, polydispersities greater than 3.0 and a range of 1 to 18% (IR spectroscopy) for HNBR. By the residual double bond (RDB) content.

One limitation in the processing of NBR and HNBR is the relatively high Mooney viscosity. In principle, NBR and HNBR with lower molecular weight and lower Mooney viscosity will have better processability. Attempts have been made to reduce the molecular weight of polymers by chewing (mechanical breakage) and by chemical means (eg using strong acids), but the process involves the use of functional groups (such as carboxylic acid and ester groups) to the polymer. It has the disadvantage of causing introduction and alteration of the microstructure of the polymer. This causes adverse changes in the properties of the polymer. In addition, this type of approach necessarily produces polymers having a broad molecular weight distribution.

While having a low Mooney (<55) and improved processability, optionally hydrogenated nitrile rubbers with the same microstructure as the rubbers currently available are difficult to manufacture using current techniques. Hydrogenation of NBR to produce HNBR results in a much larger increase in Mooney viscosity of the original polymer. This Mooney Increase Ratio (MIR) depends on the polymer grade, the level of hydrogenation and the characteristics of the feedstock and is generally around 2. In addition, the limitations associated with the generation of NBR itself determine the low viscosity range for HNBR feedstock. Currently, one of the lowest Mooney viscosity products available is available from Therban® VP KA 8837 (Bayer) with a Mooney viscosity of 55 (ML 1 + 4 ＠ 100 ° C.) and an RDB of 18%. )to be.

Karl Ziegler's findings regarding the high efficiency of certain metal salts in combination with a major group of alkylating agents, which promote olefin polymerization under mild conditions, have significant influence in chemical research and production at present. Initially, some "Ziegler-type" catalysts not only promote the proposed coordination-insertion mechanism but also perform a completely different chemical process, i.e., the exchange (or metathesis) reaction of alkenes according to the scheme shown in FIG. Found.

Acyclic diene metathesis (or ADMET) is catalyzed by a wide variety of transition metal complexes and nonmetallic systems. Heterogeneous catalyst systems based on metal oxides, sulfides or metal salts were originally used for metathesis of olefins. However, limited stability (particularly for hetero-substituents) and lack of selectivity due to numerous active sites and side reactions are major drawbacks of heterogeneous systems.

Homogeneous systems have also been designed and used to perform olefin metathesis. Homogeneous systems offer significant activity and control advantages over heterogeneous catalyst systems. For example, certain rhodium based complexes are effective catalysts for metathesis of electron rich olefins.

The discovery that certain metal-alkylidene complexes can catalyze the metathesis of olefins has led to a new development of well-defined, highly active single-position catalysts. Among them, bis- (tricyclohexylphosphine) -benzylidene ruthenium dichloride (commonly known as Grubb catalyst) is widely used due to its outstanding insensitivity to air and moisture and its high resistance to various functional groups. Is being used. Unlike molybdenum-based metathesis catalysts, the ruthenium carbene catalyst is stable against acids, alcohols, aldehydes and quaternary amine salts and can be used in various solvents (C ₆ H ₆ , CH ₂ Cl ₂ , THF, t-BuOH) Can be.

Thus, the use of transition metal catalyzed alkene metathesis is drawing attention as a synthetic method. The most commonly used catalysts are based on Mo, W and Ru. While research efforts have focused mainly on the synthesis of small molecules, the application of olefin metathesis to polymer synthesis has allowed the preparation of novel polymeric materials (such as highly stereoregular polynorbornadiene) with unprecedented properties.

The use of olefin metathesis as a means for producing low molecular weight compounds from unsaturated elastomers is of increasing interest. The principle for molecular weight reduction of unsaturated polymers is shown in FIG. 2. The use of suitable catalysts enables the cross-metathesis of unsaturated polymers and coolefins. The end result is the cleavage of the polymer chain at the unsaturated position and the generation of polymer fragments with lower molecular weight. In addition, another result of this process is to “homogenize” the polymer chain length resulting in a decrease in polydispersity. From an application and process standpoint, the narrow molecular weight distribution of the original polymer leads to improved physical properties of the vulcanized rubber, while lower molecular weight provides good process behavior.

So-called copolymers of 1,3-butadiene and various comonomers (styrene, propene, divinylbenzene and ethylvinylbenzene, acrylonitrile, vinyltrimethylsilane and divinyldimethylsilane) in the presence of the classical Mo and W catalyst systems "Depolymerization" has been investigated. Similarly, deterioration of nitrile rubber with WCl ₆ and SnMe ₄ or PhC≡CH cocatalysts was reported in 1988. However, the focus of the study is to produce low molecular weight fragments that can only be characterized by conventional chemical means and do not include teaching for the preparation of low molecular weight nitrile rubber polymers. In addition, the method is uncontrollable and produces a wide range of products.

Catalytic depolymerization of 1,4-polybutadiene is also possible in the presence of substituted olefins or ethylene (as chain transfer agent) and well-defined Grub or Schrock catalysts. General structural formulas {M (= NR ₁ ) (OR ₂ ) ₂ (= CHR) for producing low molecular weight polymers or oligomers from gelled polymers containing internal unsaturation along the polymer backbone; The use of molybdenum or tungsten compounds of M = Mo, W} has been claimed in US Pat. No. 5,446,102. However, the method also disclosed is uncontrollable and there is no teaching on the preparation of low molecular weight nitrile rubber polymers.

International applications PCT / CA02 / 00966, PCT / CA02 / 00965, and WO-03 / 002613-A1 disclose nitrile butadiene rubbers with hydrogenated and nonhydrogenated nitrile rubbers having lower molecular weight and narrower molecular weight distribution than those known in the art. It is disclosed that after the olefin metathesis of, it can optionally be prepared by hydrogenation of the resulting metathesized NBR. The document uses a so-called Grub catalyst that is different from the catalyst of the present invention.

[Summary of invention]

We finally prepare an optionally hydrogenated nitrile rubber having a lower molecular weight and narrower molecular weight distribution than is known in the art after olefin metathesis of nitrile butadiene rubber, followed by hydrogenation of the resulting metathesized NBR in the case of HNBR. It was found that it can.

Accordingly, one aspect of the invention disclosed is

a) reacting the nitrile rubber in the presence of at least one compound selected from the group consisting of compounds of formula I and any one or more coolefins; And

b) hydrogenating the product of step a) if hydrogenated nitrile rubber is desired

It is a method for producing an optionally hydrogenated nitrile rubber comprising.

Where

M ¹ is Os or Ru;

R is hydrogen or C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, C ₁ -C ₂₀ alkyl, aryl, C ₁ -C ₂₀ carboxylate, C ₁ -C ₂₀ alkoxy, C _2- C ₂₀ alkenyloxy, C ₂ -C ₂₀ alkynyloxy, aryloxy, C ₂ -C ₂₀ alkoxycarbonyl, C ₁ -C ₂₀ alkylthio, C ₁ -C ₂₀ alkylsulfonyl and C ₁ -C ₂₀ alkyl A hydrocarbon selected from the group consisting of sulfinyl;

X is selected from any anionic ligand;

L ¹ is a neutral π-binding ligand that is independent of whether they are monocyclic or polycyclic, preferably but not limited to arene, substituted arene, heteroarene;

L is phosphine, sulfonated phosphine, fluorinated phosphine, up to 3 aminoalkyl-, ammoniumalkyl-, alkoxyalkyl-, alkoxycarbonylalkyl-, hydroxycarbonylalkyl-, hydroxyalkyl- or keto From the group consisting of functionalized phosphines, phosphites, phosphinites, phosphonites, phosphineamines, arsines, styrenes, ethers, amines, amides, imines, sulfoxides, thioethers and pyridines containing alkyl- groups The ligand of choice;

Y ⁻ is a non-coordinating anion.

The process of the present invention provides a hydrogenated nitrile rubber having a molecular weight (Mw) in the range of 30,000 to 250,000, a Mooney viscosity (ML 1 + 4 내지 100 ° C.) in the range of 3 to 50, and an MWD (or polydispersity index) of less than 2.5. Can be generated.

1 shows a scheme of the interchange (or metathesis) reaction of alkenes.

2 shows the principle for molecular weight reduction of unsaturated polymers.

The term "nitrile polymer" (NBR), used throughout the specification, is intended to have a broad meaning and is a repeating unit derived from one or more conjugated dienes, one or more α, β-unsaturated nitriles and any additional one or more copolymerizable monomers. It is assumed that a copolymer having

Conjugated dienes may be all known conjugated dienes, especially C ₄ -C ₆ conjugated dienes. Preferred conjugated dienes are butadiene, isoprene, piperylene, 2,3-dimethyl butadiene and mixtures thereof. Even more preferred C ₄ -C ₆ conjugated dienes are butadiene, isoprene and mixtures thereof. Most preferred C ₄ -C ₆ conjugated diene is butadiene.

The α, β-unsaturated nitrile may be all known α, β-unsaturated nitriles, especially C ₃ -C ₅ α, β-unsaturated nitriles. Preferred C ₃ -C ₅ α, β-unsaturated nitriles are acrylonitrile, methacrylonitrile, ethacrylonitrile and mixtures thereof. Most preferred C ₃ -C ₅ α, β-unsaturated nitrile is acrylonitrile.

Preferably, the copolymer comprises repeating units derived from one or more conjugated dienes in the range from 40 to 85% by weight and repeating units derived from one or more unsaturated nitriles in the range from 15 to 60% by weight. More preferably, the copolymer comprises repeating units derived from one or more conjugated dienes in the range of 60 to 75 weight percent and repeating units derived from one or more unsaturated nitriles in the range of 25 to 40 weight percent. Most preferably, the copolymer comprises repeating units derived from one or more conjugated dienes in the range of 60 to 70 weight percent and repeating units derived from one or more unsaturated nitriles in the range of 30 to 40 weight percent.

Optionally, the copolymer may further comprise repeating units derived from one or more copolymerizable monomers, such as unsaturated carboxylic acids. Non-limiting examples of suitable unsaturated carboxylic acids are fumaric acid, maleic acid, acrylic acid, methacrylic acid and mixtures thereof. It will be apparent to those skilled in the art that repeating units derived from one or more copolymerizable monomers will replace the nitrile or diene portion of the nitrile rubber and the above mentioned values should be adjusted to 100 weight percent. In the case of the unsaturated carboxylic acids mentioned, the nitrile rubber preferably comprises repeating units derived from one or more unsaturated carboxylic acids in the range of 1 to 10% by weight of the rubber, which amount replaces the corresponding amount of conjugated diolefin. do.

Other preferred optional additional monomers are derivatives thereof (eg, esters, amides, etc.), including unsaturated mono- or di-carboxylic acids or mixtures thereof.

To produce HNBR, the substrate is first subjected to a metathesis reaction and then the substrate is hydrogenated.

Double decomposition

The metathesis reaction is carried out in the presence of at least one compound of formula (I).

<Formula I>

Where

M ¹ is Os or Ru;

R is hydrogen or C ₂ -C ₂₀ alkenyl, C ₂ -C ₂₀ alkynyl, C ₁ -C ₂₀ alkyl, aryl, C ₁ -C ₂₀ carboxylate, C ₁ -C ₂₀ alkoxy, C _2- C ₂₀ alkenyloxy, C ₂ -C ₂₀ alkynyloxy, aryloxy, C ₂ -C ₂₀ alkoxycarbonyl, C ₁ -C ₂₀ alkylthio, C ₁ -C ₂₀ alkylsulfonyl and C ₁ -C ₂₀ alkyl A hydrocarbon selected from the group consisting of sulfinyl;

X is selected from any anionic ligand;

L ¹ is a neutral π-binding ligand that is independent of whether they are monocyclic or polycyclic, preferably but not limited to arene, substituted arene, heteroarene;

L is phosphine, sulfonated phosphine, fluorinated phosphine, up to 3 aminoalkyl-, ammoniumalkyl-, alkoxyalkyl-, alkoxycarbonylalkyl-, hydroxycarbonylalkyl-, hydroxyalkyl- or keto From the group consisting of functionalized phosphines, phosphites, phosphinites, phosphonites, phosphineamines, arsines, styrenes, ethers, amines, amides, imines, sulfoxides, thioethers and pyridines containing alkyl- groups The ligand of choice;

Y ⁻ is a non-coordinating anion.

Preferred are compounds of formula I, wherein L is trialkylphosphine, L ¹ is 1-methyl-4-iso-propylphenyl, X is chloride ion, R is phenyl and M is ruthenium.

The amount of compound will depend on the nature of the compound (s) and the catalytic activity. Typically, the ratio of compound (s) to NBR ranges from 0.005 to 5, preferably from 0.025 to 1, and more preferably from 0.1 to 0.5.

The metathesis reaction can be carried out in the absence of any coolefin. However, the reaction rate is improved when the metathesis reaction is carried out in the presence of coolefins. The coolefin can be a hydrocarbon or can be functionalized to not deactivate the metathesis catalyst or otherwise interfere with the reaction. Preferred olefins include, but are not limited to, C ₂ to C ₁₆ linear or branched olefins such as ethylene, isobutene, styrene or 1-hexene. If the coolefin is a liquid (such as 1-hexene), the amount of coolefin used is preferably in the range of 1 to 200% by weight. If the coolefin is a gas (such as ethylene), the amount of coolefin used is generally 2 * 10 ⁴ Pa to 2.5 * 10 ⁷ Pa, preferably 1 * 10 ⁵ Pa to 1 * 10 ⁵ Pa, and more preferably Is an amount which forms a pressure in the reaction vessel in the range of 5.2 * 10 ⁵ Pa to 4 * 10 ⁶ Pa.

The metathesis reaction can be carried out in any suitable solvent that does not deactivate the catalyst or otherwise interfere with the reaction. Preferred solvents include, but are not limited to, dichloromethane, benzene, toluene, tetrahydrofuran, methyl ethyl ketone, cyclohexane, and the like. Most preferred solvent is monochlorobenzene (MCB). In certain cases, the coolefin can itself act as a solvent (eg 1-hexene), in which case no other solvent is needed.

The concentration of NBR in the reaction mixture is not critical, but obviously it should be an amount that does not interfere with the reaction, for example if the mixture is too viscous to be stirred efficiently. Preferably, the concentration of NBR is in the range of 1 to 40% by weight, most preferably 6 to 15% by weight.

The metathesis reaction is preferably carried out at a temperature in the range of 20 to 140 ° C, more preferably 60 to 120 ° C.

The reaction time will depend on a number of factors including the cement concentration, the amount of catalyst used and the temperature at which the reaction is carried out. Metathesis is generally completed within 2 hours of initiation under typical conditions. The progress of the metathesis reaction can be monitored by standard analytical techniques, for example using GPC or solution viscosity. In all cases mentioned throughout the specification, the molecular weight distribution of the polymer was determined by gel permeation chromatography (GPC) using the Waters 2690 Separation Module and Waters 410 running Waters Millenium software version 3.05.01. Measured with a differential refractometer (Waters 410 Differential Refractometer). Samples were dissolved in tetrahydrofuran (THF) stabilized with 0.025% BHT. The column used for the measurement was three consecutive mixed-B gel columns from Polymer Labs. The reference standard used was a polystyrene standard from American Polymer Standards Corp.

Hydrogenation

Reduction of the product from the metathesis reaction can be carried out using standard reduction techniques known in the art. For example, homogeneous hydrogenation catalysts known to those skilled in the art such as Wilkinson catalyst {(PPh ₃ ) ₃ RhCl} and the like can be used.

Processes for hydrogenation of NBR are known and can also be used for the production of hydrogenation products according to the invention. In general, rhodium or titanium is used as catalyst, but platinum, iridium, palladium, rhenium, ruthenium, osmium, cobalt or copper in metal form, preferably in the form of metal compounds, may also be used (eg US 3,700,637; DE- PS 2,539,132; EP-A-134 023; DE-OS 35 41 689; DE-OS 35 40 918; EP-A 298 386; DE-OS 35 29 252; DE-OS 34 33 392; US 4,464,515; and US 4,503,196 Reference).

Suitable catalysts and solvents for the hydrogenation of homogeneous phases are described below and in GB 1558491, and EP 471,250 of Bayer AG, which are already incorporated herein by reference. It is not intended to limit the catalysts and solvents for hydrogenation useful in the present invention, which are provided by way of example only.

Selective hydrogenation can be accomplished by rhodium-containing catalysts. Preferred catalysts are of the formula (R ⁸ _m B) _l RhX ³ _n , wherein each R ⁸ is a C ₁ -C ₈ -alkyl group, a C ₄ -C ₈ -cycloalkyl group, a C ₆ -C ₁₅ -aryl group Or a C ₇ -C ₁₅ -aralkyl group, B is a phosphorus, arsenic, sulfur, or sulfoxide group S═O, X ³ is hydrogen or an anion, preferably a halide, more preferably a chloride or bromide ion, l is 2, 3 or 4, m is 2 or 3, n is 1, 2 or 3, preferably 1 or 3. Preferred catalysts are tris (triphenylphosphine) -rhodium (I) -chloride, tris (triphenylphosphine) -rhodium (III) -chloride and tris (dimethylsulfoxide) -rhodium (III) -chloride, and formula ( Tetrakis (triphenylphosphine) -rhodium hydride of (C ₆ H ₅ ) ₃ P) ₄ RhH, and the corresponding compound in which the triphenylphosphine residue is substituted with a tricyclohexylphosphine residue. The catalyst can be used in small amounts. Suitable amounts are in the range of 0.01% to 1.0% by weight, preferably 0.03% to 0.5% by weight, most preferably 0.1% to 0.3% by weight, based on the weight of the polymer.

It is known to use catalysts with cocatalysts which are ligands of the formula R ⁸ _m B wherein R, m and B are as defined above and m is preferably 3. Preferred B is phosphorus and the R groups can be the same or different. Thus triaryl, trialkyl, tricycloalkyl, diaryl monoalkyl, dialkyl monoaryl, diaryl monocycloalkyl, dialkyl monocycloalkyl, dicycloalkyl monoaryl or dicycloalkyl monoaryl cocatalysts can be used. . Examples of cocatalyst ligands are shown in US Pat. No. 4,631,315, the disclosure of which is incorporated by reference. Preferred cocatalyst ligands are triphenylphosphines. Cocatalyst ligands are preferably used in amounts ranging from 0.3 to 5% by weight, more preferably from 0.5 to 4% by weight, based on the weight of the copolymer. Further, the weight ratio of rhodium-containing catalyst compound to cocatalyst is preferably in the range of 1: 3 to 1:55, more preferably 1: 5 to 1:45. The weight of the cocatalyst, based on 100 parts by weight of rubber, is suitably in the range of 0.1 to 33, more suitably 0.5 to 20, preferably 1 to 5, most preferably more than 2 to less than 5.

Hydrogenation can be advantageously carried out in situ, ie in the same reaction vessel in which the metathesis step is carried out without first isolating the metathesized product. The hydrogenation catalyst is simply added to the vessel and then treated with hydrogen to produce HNBR.

The hydrogenation of the invention is preferably greater than 50% of the residual double bonds (RDB) present in the starting nitrile polymer, preferably greater than 90% of the RDB, more preferably greater than 95% of the RDB, and most preferably the RDB. It is understood that more than 99% of are hydrogenated.

The low Mooney NBR and preferred HNBR of the present invention can be characterized by standard techniques known in the art. For example, the molecular weight distribution of the polymer was measured by Gel Permeation Chromatography (GPC) using Waters 2690 Separation Module and Waters 410 Differential Refractometer running Waters Millennium Software version 3.05.01. Samples were dissolved in tetrahydrofuran (THF) stabilized with 0.025% BHT. The column used for the measurement was three consecutive mixed-B gel columns from Polymer Labs. The reference standard used was a polystyrene standard from American Polymer Standards Corporation.

The Mooney viscosity of the rubber was measured using ASTM Test Method D1646.

Example  1-3

Tris (triphenylphosphine) rhodium chloride (Wilkinson hydrogenation catalyst), triphenylphosphine (TPP) and monochlorobenzene (MCB) were purchased from JMI, Elf Atochem and PPG, respectively, and used as such. It was. Document salts of ruthenium chloride (Ru catalyst), triflate (CF ₃ SO ₃₎ - cationic tricyclohexylphosphine - (η ⁶ -1- methyl-4-iso-propylphenyl) -2-phenyl-inde alkylpiperidinyl Angew. Chem. Int. Ed. Engl; 2003 , 42, 4524-4527.

[Complexed]

The metathesis reaction was carried out in the Parr high pressure reactor under the following conditions:

Cement concentration 12 wt%

Coolefin Ethylene ＠ 400 psi

Stirrer Speed 600 rpm

Reactor temperature 80 ℃

See Ru catalyst loading table A

Solvent monochlorobenzene

Statistical butadiene-acrylonitrile copolymers having a substrate acrylonitrile content of 34 mol% and a Mooney viscosity (ML (1 + 4) ＠ 100 ° C) of 35

For Examples 1-2, the reactor was heated to the desired temperature and 60 mL of monochlorobenzene solution containing Ru catalyst was added to the reactor. The reactor was pressurized to the desired ethylene pressure. The temperature was kept constant for the duration of the reaction. The temperature was controlled using a cooling coil connected to a temperature controller and a thermal sensor. The progress of the reaction was monitored using solution viscosity measurements on 6% cement.

[Hydrogenation]

The hydrogenation reaction was carried out in the same reactor as metathesis under the following conditions:

Cement Solid Concentration 12%

H ₂ (gas) pressure 1200 psi

Stirrer Speed 600 rpm

Reactor temperature 138 ℃

Catalyst Loading (Wilkinson) 0.07 phr

Triphenylphosphine 1 phr

Solvent monochlorobenzene

The cement from the metathesis reaction was degassed three times with H ₂ (100 psi) with sufficient stirring. The temperature of the reactor was raised to 130 ° C. and 60 mL of monochlorobenzene solution containing Wilkinson catalyst and triphenylphosphine was added to the reactor. The temperature was increased to 138 ° C. and kept constant for the duration of the reaction. The hydrogenation reaction was monitored by measuring the level of residual double bond (RDB) at various intervals using IR spectroscopy.

-Experiment details Example 1 Example 2 Terban®
A3407
(compare) Ru catalyst loading (phr) 0.035 0.016 N / A Temperature 40 ℃ 40 ℃ N / A Ethylene pressure 400 psi 400 psi N / A Final residual double bond <1% <1% <1% Final polymer Mooney
(ML 1 + 4 ＠ 100 ℃) 28.2 43.9 65 GPC Mn (kg / mol) 64 83 97 Mw (kg / mol) 150 237 314 PDI 2.3 2.9 3.2

Terban® A3407 is commercially available from Bayer, and used for comparison purposes. This was produced by simple hydrogenation using the same substrate as in Example 1-2. For a typical commercial product, Mn is 97 kg / mol, while Mw is 314 kg / mol. As expected, the molecular weights (Mw and Mn) were reduced by metathesis reactions, and the polymer weight distribution decreased from 3.4 for the starting substrate to 2.0 for the metathesized product.

Claims (9)

a) reacting the nitrile rubber in the presence of a triflate salt of tricyclohexylphosphine- (η ⁶ -1-methyl-4-iso-propylphenyl) -2-phenyl-indenylidene-ruthenium chloride; And b) for the hydrogenated nitrile polymer, hydrogenating the product of step a) Comprising, a method of producing a hydrogenable nitrile rubber. The process of claim 1 wherein the nitrile rubber is hydrogenated and the hydrogenation is carried out under homogeneous catalyst conditions. 3. Process according to claim 2, wherein the hydrogenation is carried out in situ, ie without first isolating the product of step a). The process according to claim 1, wherein the weight ratio of compound to nitrile rubber is in the range of 0.005 to 5. 5. The process according to claim 1, wherein step a) is further carried out in the presence of one or more coolefins. The process according to claim 1, wherein the process is carried out in an inert solvent selected from the group consisting of monochlorobenzene, dichloromethane, benzene, toluene, tetrahydrofuran and cyclohexane. The process according to claim 1, wherein the nitrile rubber is hydrogenated and hydrogenation is carried out using a catalyst of the formula (R ⁸ _m B) _l RhX ³ _n Where Each R ⁸ is independently selected from the group consisting of a C ₁ -C ₈ -alkyl group, a C ₄ -C ₈ -cycloalkyl group, a C ₆ -C ₁₅ -aryl group and a C ₇ -C ₁₅ -aralkyl group; B is selected from the group consisting of phosphorus, arsenic, sulfur, and sulfoxide groups (S═O); X ³ is selected from the group consisting of hydrogen and an anion; l is 2, 3 or 4, m is 2 or 3 and n is 1, 2 or 3. The process of claim 7 wherein the hydrogenation catalyst is (PPh ₃ ) ₃ RhCl. delete

Images