WO2013098056A1

WO2013098056A1 - Purification of optionally hydrogenated nitrile rubber

Info

Publication number: WO2013098056A1
Application number: PCT/EP2012/074601
Authority: WO
Inventors: Christopher Ong; Stephen Pask
Original assignee: Lanxess Deutschland GmbH
Current assignee: Lanxess Deutschland GmbH
Priority date: 2011-12-28
Filing date: 2012-12-06
Publication date: 2013-07-04
Anticipated expiration: 2014-06-28
Also published as: TW201343677A

Abstract

The present invention provides a novel process for the purification of an optionally hydrogenated nitrile rubber comprising contacting said optionally hydrogenated nitrile rubber with at least one ionic liquid thereby removing a broad variety of impurities, including various catalysts and degradation products thereof, iron containing residues and degradation products thereof, as well as compounds used either in the emulsion polymerisation for preparing the nitrile rubber or the optional subsequent metathesis and/or optional hydrogenation reaction or any degradation products thereof.

Description

_ _

Purification of optionally hydrogenated nitrile rubber

FIELD OF THE INVENTION

This invention provides a process for the purification of optionally hydrogenated nitrile rubber by contacting such optionally hydrogenated nitrile rubber with specific solvents.

BACKGROUND OF THE INVENTION

Elastomers are widely used in many rubber-technology products, such as rubber tubing, transmission belts, seals, membranes, fabric coverings, shoe soles, profile sections, films, packaging materials and many other products. For applications in the field of injection-molded articles, applications involving contact with food, in the field of medicine, in the electronics industry and as starting products for further reactions, such as hydrogenations in the presence of sensitive transition metal catalysts, the elastomers need to have the impurities removed in an elaborate way. Such impurities and undesired compounds can originate from the elastomer production process, in which different additives and complex metal catalysts are used, namely during radical polymerization in an aqueous emulsion. Such additives and catalysts are also subject to undesired degradation reactions which further results in unwanted byproducts.

In the medical sector and for contact with food the use of elastomers with a too high impurity level is therefore often greatly restricted on toxicological grounds, the limit on the impurity level being dependent both on the type of impurity and on its concentration. Impurity levels which are less than 2 wt. %, however, are often required. The use of elastomers with a too high impurity level in electronic applications is often only conditionally possible. This is true especially when the impurities contain water and/or ions, since these can greatly affect the corrosion behavior and conductivity behavior of the electronic products, and they cannot always be removed by the action of heat without leaving a residue. Furthermore elastomers with an impurity level of more than about 4 wt. %, based on the sum of the impurities and the elastomer, often cannot be used for subsequent reactions such as e.g. metatheses and/or hydrogenations, in which it is necessary to operate in the presence of sensitive transition metal catalysts, since these impurities make the reaction control more difficult, lengthen the reaction times and reduce the efficiency of the transition metal catalyst. In the case of hydrogenation, the impurities can additionally contribute very significantly to corrosion and therefore wear of the systems needed for the hydrogenation. For many other applications such as injection-molded articles or extruded articles, the use of elastomers with a too high impurity level (more than about 3 wt. %) can lead to reduced surface quality of the articles due to efflorenscence as well as to mold contamination.

For the applications mentioned above, the purification of the elastomers with respect to impurities is typically carried out by expensive neutralization, coagulation, precipitation and washing - - processes in suitable organic substances, such as alcohols, ketones, ethers, water and mixtures thereof. In the alternative impurities are removed by contacting the reaction mixtures with ion exchange resins disposing of functional groups able to bind such impurities. Nevertheless complete purification cannot in principle be guaranteed.

A particular problem involves the separation of low-molecular, sometimes high-boiling (above 150°C), weakly water-soluble and/or water-insoluble impurities such as emulsifiers, fatty acids, fatty acid salts and fatty acid esters, monomers and derivatives thereof, such as dimers, oligomers or other undesired reaction products of the monomers with other components of the reaction system, organic catalyst residues and ligands, which remain in the elastomer when the elastomers have been prepared by emulsion polymerization followed by conventional purification processes.

Using the processing and purification methods known in the prior art, these impurities often cannot be separated sufficiently, and even then only with significant economic outlay, since they become encapsulated during the latex coagulation of the elastomer and are therefore less accessible to washing processes. Fractional precipitation of the elastomers from solution followed by a drying step is known in order to separate low-molecular weight impurities and/or impurities soluble in organic solvents (precipitating agents) in which the polymer is insoluble, for example methanol as a solvent for the impurities in the case of nitrile rubber and polychloroprene rubber. Such impurities are for example emulsifiers, fatty acids, fatty acid esters, fatty acid salts of sodium, potassium or calcium, unreacted monomers, molecular weight modifiers, catalyst components, and any reaction products thereof. However, such fractional precipitation entails high costs on the industrial scale and is ecologically disadvantageous owing to the large amounts of solvents and precipitating agents required.

The utilization of ionic liquids for the removal of certain additives from various organic mediums has already been investigated. WO 2002/34863 A teaches a process for removing mercaptans from hydrocarbon streams, for example crude oil and natural gas, by a) adding a mercaptan-containing hydrocarbon feedstream to an ionic liquid solution or dispersion of one or more basic metal salts to form mercaptides, which are then either precipitated from solution or are dissolved or dispersed in the ionic liquid and b) separating the resulting de-marcaptanized hydrocarbon feedstream from the ionic liquid. The flow of hydrocarbons can either stream over/through the ionic liquid or be brought into contact in stirred tanks. The basic salts can be virtually any base capable of reacting with mercaptans to form mercaptides.

US 2004/0133058 A discloses a process for separating close-boiling or azeotropic mixtures by using ionic liquids as selective additives in rectification. The process allows to separate liquids or condensable gases in the condensed state wherein an entrainer is used which is an ionic liquid and - - which brings a change in the separation factor of the components to be separated divergent from one. The ionic liquid is present at a total concentration of 5 to 90 mol %. This process is told to be superior to conventional extractive rectification regarding costs and energy. It is mentioned as particularly suitable for the following applications, eg. azeotropes: amines/water, THF/water, formic acid/water, alcohols/water, acetone/methanol, acetate/water, acrylate/water or close-boiling mixtures like acetic acid/water, C4 hydrocarbons, C4 hydrocarbons, and alkanes/alkenes.

US 2005/0010076 A discloses a process for the purification of hydrocarbons or mixtures of hydrocarbons through the removal of polarisable impurities with ionic liquids. Of specific importance is the removal of sulfur-containing impurities from diesel fuels or other petrol fractions to a content below a level of 50 ppm, which process is told to be significantly superior to the removal by hydrogenation methods. In addition the process also allows a dehalogenation which avoids the classical drawbacks of dehalogenation by hydrogenation (as high pressure and temperature, release of corrosive HC1 gas).

US 2003/0085156 A also discloses a process for the removal of organosulfur compounds from a hydrocarbon material (diesel fuel, gasoline, jet fuel etc.) by contacting the hydrocarbon material with an ionic liquid, resulting in the extraction of the sulphur compound into the ionic liquid. The process can be conducted either batch-wise or continuously. It is described that a counter-current contactor can be utilized which allows for the hydrocarbon material to flow into the bottom of the contactor and rise through the ionic liquid (which enters through the top and exits through the bottom) and exit through the top. In a further embodiment a process for the regeneration of the ionic liquid is described through the removal of the organosulfur compounds from the ionic liquid by means of vapourization or solvent extraction.

US 2005/0090704 A relates to a process for the liquid-liquid extraction or liquid-gas extraction of olefins from a mixture of organic compounds of olefins and aliphatics, wherein the olefins are extracted by means of a phase comprising at least one ionic liquid with the extraction being carried out in countercurrent and the phase comprising the ionic liquid.

With regard to molecular weight degradation of polymers via a metathesis reaction the metathesis itself is a well documented process. A number of ruthenium-containing catalysts are e.g. known to be particularly suitable for the selective metathesis of nitrile rubber which encompasses the cleavage of the carbon-carbon double bonds without concomitant reduction of the carbon-nitrogen triple bonds present in the nitrile rubber.

US 2003/0088035 A teaches the use of bis(tricyclohexylphosphine)benzylidene ruthenium dichloride in such metathesis reaction. First the rubber is dissolved in a suitable solvent to provide - - a viscous rubber solution. The catalyst is then dissolved in the rubber solution and a co-olefin can be added to such solution. Following the metathesis of the nitrile rubber the rubber solution can be optionally hydrogenated. Similarly, US 2004/0132891 A teaches the use of l,2-bis-(2,4,6- trimethylphenyl)-2-imidazolidinylidene) (tricyclohexylphosphine)-ruthenium (phenyl methylene) dichloride for the metathesis of nitrile rubber, however, in the absence of a co-olefin. The disclosure in prior art regarding a potential separation of the metathesis catalyst from the polymer is relatively limited. Additionally there is no disclosure or teaching given at all which pays attention to the removal of any undesired by-products or impurities. US 6,376,690 Bl relates to the removal of metal complexes from reaction mixtures and teaches the use of a separation process in which a solution containing a solubility-enhancing compound is added to the original reaction mixture containing the metal complexes wherein the added solution is immiscible with the original reaction mixture. Depending on whether the reaction mixture is either of aqueous or organic nature (preferably on the basis of CH₂CI₂) the second solution is just the opposite and the solubility enhancing compound is chosen in a way that it enhances the metal catalysts solubility in said second solution. The solubility-enhancing compounds comprise e.g. phosphines, sulfonated phosphines, phosphites, phosphinites, phosphonites, arsines, stibines, ethers, amines, amides, imines, sulfoxides, carboxyls, nitrosyls, pyridines, and thioethers. The metal catalyst on the basis of e.g. cadmium, chromium, cobalt, copper, gold, iridium, iron, magnesium, manganese, mercury, molybdenum, nickel, osmium, palladium, platinum, rhenium, rhodium, ruthenium, silver, techneticum, tungsten, and zinc, once reacted with the solubility-enhancing compound migrates out of the reaction mixture into the second solution. This solution is then removed from the reaction solution. The process is told to be in particular amenable for the post- reaction separation of ruthenium and osmium metathesis catalysts from the desired products. However, such process, disadvantageous^ involves the addition of additives which - if not fully removed - can lateron interfere with the hydrogenation catalyst which is typically used in a subsequent step to hydrogenate the nitrile rubber. Secondly, the separation of two immiscible solutions while relatively easy on small scale is quite a complex process on a commercial scale of grand scale.

The prior art further describes other completely different processes to remove catalysts or catalyst degradation products which originate from metathesis reactions.

WO-A-2006/047105 discloses a process for separating a homogeneous metathesis catalyst and, optionally, one or more homogeneous metathesis degradation products from a metathesis reaction mixture containing in addition to said metathesis catalyst and said metathesis degradation product(s) one or more olefin metathesis products, one or more unconverted reactant olefins, and optionally a solvent. Said process comprises contacting the metathesis reaction mixture with a - - nanofiltration membrane, e.g. based on polyimides, so as to recover a permeate containing a substantial portion of the olefin reaction products, the unconverted reactant olefins, and optional solvent, and a retentate containing the metathesis catalyst, and optionally, metathesis catalyst degradation products(s). The metathesis reaction mixture used may be obtained by homo- metathesis, cross-metathesis, ring-closing metathesis, or ring-opening metathesis polymerisation.

In Tetrahedron Letters, 1999, Vol. 40, 4137-4140 it is disclosed that the products of a ring- closing metathesis reaction, in particular of diethyl diallylmalonate using RuCl₂(=CHPh)(PCy₃) as a catalyst may be successfully purified of unwanted ruthenium using the water-soluble coordinating phosphine tris(hydroxymethyl)phosphine (i.e. P(CH₂OH)₃) which readily coordinates to the ruthenium resulting in a complex soluble in water. In Organic Letters, 2001, Vol. 3, No. 9, 1411- 1413 it is described to remove coloured ruthenium byproducts generated during olefin metathesis reactions with Grubbs-I or Grubbs-II catalysts by treating the crude reaction products with triphenylphosphine oxide or dimethylsulfoxide, followed by filtration through silica gel.

Polymer hydrogenation is a well known operation, as disclosed, for example, in US-A- 4,396,761, US-A-4,510,293, US-A-5,258,467 and US-A-4,595,749. The subsequent separation of the hydrogenation catalyst or degradation products thereof from the polymer, however, is not always described in detail or even at all.

More specifically, certain rhodium containing catalysts are known to be particularly suitable for the selective hydrogenation of nitrile rubber, namely the reduction of the carbon-carbon double bonds without concomitant reduction of the carbon-nitrogen triple bonds present in nitrile rubber. Such hydrogenated nitrile rubber is less susceptible to heat-induced degradation in comparison to unsaturated nitrile rubber.

For example, US-A-4,464,515 teaches the use of hydrido rhodium tetrakis (triphenylphosphine) catalyst, i.e. HRh(PPh₃)₄, in a process to selectively hydrogenate unsaturated nitrile rubber. There is no further disclosure about removing the hydrogenation catalyst after the hydrogenation.

GB-A-1,558,491 teaches the use of chloro rhodium tris(triphenylphosphine) (RhCl(PPh₃)₃) as catalyst in a similar process to hydrogenate unsaturated nitrile rubber. The hydrogenation product is separated off from the reaction solution by treatment with steam or by pouring into methanol and is subsequently dried at elevated temperature and reduced pressure. Once more no teaching is provided how the hydrogenation catalyst might be removed.

Additionally certain ruthenium containing catalysts are known to be particularly suitable for either the selective metathesis or hydrogenation of nitrile rubber. The process of utilizing ruthenium - - containing catalysts for the homogeneous hydrogenation of nitrile rubber is also well known. In US 5,075,388 it is disclosed to hydrogenate nitrile rubber in the presence of an NH₂ containing compound selected from ammonia and a C₁.₂₀ primary amine. US-A-6,084,033 teaches the use of a rhodium-ruthenium bimetallic complex catalyst for the hydrogenation of nitrile rubber. However, there is no teaching at all, how to remove the respective catalyst residues from the hydrogenated nitrile rubber.

US-A-4,631,315 teaches the hydrogenation of a nitrile rubber dissolved in a low molecular weight ketone solvent using a ruthenium-based catalyst. After hydrogenation, the polymer is separated from the solution by conventional methods, for example by (vacuum) evaporation, by blowing in water vapour or by addition of a non-solvent. A drying treatment is then carried out to remove remaining solvent or water.

In the above references the unsaturated nitrile rubber is first dissolved in a suitable solvent to provide a viscous rubber solution. The catalyst is then dissolved in the rubber solution. These hydrogenation processes are said to be homogeneous because the substrate and catalyst are contained in the same phase. An advantage of the above homogeneous hydrogenation processes is that they require minimal amounts of catalyst to effect the hydrogenation. However, a major disadvantage of such processes is that it is difficult to remove the catalyst from the reaction mixture once the reaction is complete. By comparison, in a heterogeneous process, i.e. where the catalyst is not dissolved in the reaction medium, the catalyst may be readily removed by filtration or centrifugation.

Besides rhodium and ruthenium residues, iron residues may also be present in the hydrogenated nitrile polymer. Iron-containing residues can occur due to minimum corrosion or degradation which might happen in any metal vessel or pipes or alternatively due to the fact that iron-containing compounds might have been used as activators in the polymerisation of the nitrile rubber. Iron, ruthenium and rhodium are active catalytic metals and therefore, it is desirable to remove them from the nitrile rubber as well as the hydrogenated rubber in order to improve the overall quality of the product. Furthermore, the high price of rhodium provides an economic incentive for its recovery.

A different approach in order to recover certain catalyst residues from reaction mixtures and in particular optionally hydrogenated rubber encompasses the use of ion-exchange resins.

US-A-4,985,540 discloses a process for removing rhodium-containing catalyst residues from hydrogenated nitrile rubber by contacting a functionalized ion exchange resin with a hydrocarbon phase, which contains the hydrogenated nitrile rubber, the rhodium-containing catalyst residues and - - a hydrocarbon solvent. It is said that such process is capable of removing rhodium from viscous solutions containing less than 10 ppm rhodium (weight rhodium/weight solution). The ion- exchange resins utilized are characterized as being macroreticular and modified with functional groups selected from amine, thiol, carbodithioate, thiourea, and dithiocarbamate functional groups.

In US-6,646,059 B2 it is disclosed to remove iron- and rhodium-containing residues from a solution of hydrogenated nitrile rubber which has been obtained by hydrogenating a nitrile rubber in the presence of a rhodium-based catalyst. Such process utilizes a specific monodispersed macroporous cross-linked styrene-divinylbenzene copolymer resin having thiourea functional groups. The fact that the ion-exchange resin is monodispersed is considered important for the successful performance of the process.

US-A-5,208,194 further teaches the use of a sulfonic acid functionalized ion exchange resin for the recovery of Group VIII metal complexes from dilute organic solutions. US 2004/0026329 A teaches of the recovery of transition metals through binding of the metal to functionalized polymer fibres. The polymer fibre is suitably a polyolefin, a fluorinated polyethylene, cellulose or viscose which is functionalised by radiation grafting of at least one monomer.

Notwithstanding the above methods of the prior art, there remains room for improving the removal of catalyst residues as well as other unwanted byproducts from both, nitrile rubber as well as hydrogenated nitrile rubber, in particular in view of the additional problem that the solutions containing the aforementioned polymers have a substantial viscosity.

SUMMARY OF THE INVENTION

The present invention relates to a process for the purification of an optionally hydrogenated nitrile rubber comprising contacting the optionally hydrogenated nitrile rubber with at least one ionic liquid.

DETAILED DESCRIPTION

For the purposes of the present patent application and invention, all the definitions of radicals, parameters or explanations given above or below in general terms or in preferred ranges can be combined with one another in any way, i.e. including combinations of the respective ranges and preferred ranges. The term "substituted" used for the purposes of the present patent application in respect of the metathesis catalyst or the salt of the general formula (I) means that a hydrogen atom on an indicated radical or atom has been replaced by one of the groups indicated in each case, with the - - proviso that the valence of the atom indicated is not exceeded and the substitution leads to a stable compound.

For the successful performance of the process according to the present invention it is essential that the optionally hydrogenated nitrile rubber is contacted with at least one ionic liquid.

Ionic liquids to be used in the process of the invention are salts or salt mixtures which are liquid in a temperature range from -20°C to 300°C, preferably from 0°C to 150°C, and particularly preferably from 20°C to 100°C.

Ionic liquids are typically defined through both, their cationic and their anionic portions.

For the present invention the ionic liquid can represent, but is not restricted to compounds on the basis of quaternary ammonium cations, quaternary phosphonium cations, optionally substituted pyridinium cations, optionally substituted imidazolium cations, optionally substituted pyrazolium cations, and optionally substituted pyrimidinium cations.

Preferably the process according to the present invention is performed using at least one ionic liquid which is selected from the group consisting of the ionic liquids having the general formulae

(2)

(1 ) (3)

(5)

wherein

n-

A¹ shall mean an anion selected from the group consisting of hexafluorophosphate (PF₆ ^"), nitrate (NO₃)^", halides, preferably fluoride, chloride, bromide or iodide, sulfates, sulfonates, aluminates, carboxylates, - - phosphates and borates, with n meaning 1, 2 or 3 depending on the negative charge of the aforementioned anions and (1/n) therefore representing 1 for a one time negatively charged anion, 1/2 for a two times negatively charged anion and 1/3 for a three times negatively charged anion,

X is nitrogen or phosphorous,

R¹, R², R³, R⁴, R⁵ and R⁶ are identical or different and represent hydrogen, halide, alkoxy, alkyl, substituted alkyl, aryl, preferably phenyl, substituted aryl, and

Z¹, Z², Z³ are identical or different and represent carbon (C) or nitrogen (N), under the first proviso, that at least one of Z¹, Z², and Z³ is nitrogen and under the second proviso that when any of Z¹, Z², Z³ are nitrogen the attached R¹, R², or R³group is null.

Preferably the process according to the present invention is performed in the presence of at least one ionic liquid pursuant to one of the aforementioned general formulae (l)-(5) wherein n is 1 and A- represents PF₆ ^", N0₃ ^", F\ CI^", Br , Γ, R⁷S0₃ ^", R⁷OS0₃ ^", R⁷C0₃ ^", BF₄ ^", and B(R⁷)₄ ^", where R⁷ is identical or different and represents alkyl, substituted alkyl, aryl, more preferably phenyl, substituted aryl, or alkoxy.

In one more preferred embodiment the process according to the present invention is performed in the presence of at least one ionic liquid of general formula (1) wherein n is 1 and

A- represents PF₆ ^", N0₃ , F\ CI^", Br , Γ, R⁷S0₃ ^", R⁷OS0₃ ^", R⁷C0₃ ^", BF₄ ^", and B(R⁷)₄ ^", where R⁷ is identical or different and represents alkyl, substituted alkyl, aryl, even more preferably phenyl, substituted aryl, or alkoxy,

X is nitrogen or phosphorus and

R¹, R², R³, and R⁴ are identical or different and shall mean alkoxy, alkyl or aryl each having 1 -25 carbon atoms.

In a further more preferred embodiment the process according to the present invention is performed in the presence of at least one ionic liquid of general formula (2) wherein n is 1 and

R¹, R², R³, R⁴, R⁵ and R⁶ are identical or different and shall mean alkoxy, alkyl or aryl each having

1-25 carbon atoms.

In a further more preferred embodiment the process according to the present invention is performed in the presence of at least one ionic liquid of general formula (3) wherein n is 1 and _ -

A- represents PF₆\ N0₃ ^", F\ CI^", Br , Γ, R⁷S0₃ ^", R⁷OS0₃ ^", R⁷C0₃ ^", BF₄ ^", and B(R⁷)₄ ^", where R⁷ is identical or different and represents alkyl, substituted alkyl, aryl, even more preferably phenyl, substituted aryl, or alkoxy,

R¹, R², R³, R⁴, and R⁵ are identical or different and shall mean alkoxy, alkyl or aryl each having 1 - 25 carbon atoms.

More preferably the process according to the present invention is performed in the presence of at least one ionic liquid of general formula (4) wherein n is 1 and

A- represents PF₆ ^", N0₃ , F\ CI^", Br , Γ, R⁷S0₃ ^", R⁷OS0₃ ^", R⁷C0₃ ^", BF₄ ^", and B(R⁷)₄ ^", where R⁷ is identical or different and represents alkyl, substituted alkyl, aryl, preferably phenyl, substituted aryl, or alkoxy,

R¹, R², R³, R⁴, and R⁵ are identical or different and shall mean alkoxy, alkyl or aryl each having

1-25 carbon atoms.

More preferably the process according to the present invention is performed in the presence of at least one ionic liquid of general formula (5) wherein n is 1 and

Z¹, Z², Z³ are identical or different and represent carbon (C) or nitrogen (N), under the first proviso, that at least one of Z¹, Z², and Z³ is nitrogen and under the second proviso that when any of Z 1 , Z2 , Z 3 are nitrogen the attached R 1 , R2 , or R 3 group is null, and R¹, R², R³, R⁴, R⁵ and R⁶ are identical or different alkoxy, alkyl or aryl radicals each having 1 -25 carbon atoms. In a specific embodiment the process of the present invention is performed using at least one ionic liquid selected from the group consisting of l-ethyl-3-methyl-pyridinium ethylsulfate, l-ethyl-3- methyl-imidazolium ethylsulfate, l-methyl-3-butylimidazolium chloride, l-methyl-3-ethylimidazo- lium chloride, N-butylpyridinium chloride, tetrabutylphosphonium chloride, ammonium hexa- fluorophosphate, ammonium tetrafluoroborate, ammonium tosylate, ammonium hydrogen sulphate, pyridinium hexafluorophosphate, l-methyl-3 -butyl imidazolium hexafluorophosphate, pyridinium tetrafluoroborate, pyridinium hydrogen sulphate, N-butylpyridinium hexafluorophosphate and combinations of two or more of the aforementioned ionic liquids.

Nitrile rubbers:

For the purposes of the present invention, nitrile rubbers, also referred to as "NBR" for short, are rubbers which are copolymers or terpolymers containing repeating units of at least one α,β- unsaturated nitrile, at least one conjugated diene and optionally one or more further copolymerizable monomers. - -

Such nitrile rubbers and processes for producing such nitrile rubbers are well known, see, for example, W. Hofmann, Rubber Chem. Technol. 36 (1963) 1 and Ullmann's Encyclopedia of Industrial Chemistry, VCH Verlagsgesellschaft, Weinheim, 1993, pp. 255-261.

The conjugated diene in the nitrile rubber may be of any kind. It is preferred to use (C4-C6) conjugated dienes. Particular preference is given to 1 ,2-butadiene, 1,3-butadiene, isoprene, 2,3- dimethylbutadiene, piperylene or mixtures thereof. More particular preference is given to 1,3- butadiene and isoprene or mixtures thereof. 1,3 -Butadiene is especially preferred.

As α,β-unsaturated nitrile it is possible to use any known α,β-unsaturated nitrile, preference being given to (C3-C5) α,β-unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile or mixtures thereof. Acrylonitrile is particularly preferred.

One particularly preferred nitrile rubber is a copolymer of acrylonitrile and 1,3-butadiene.

As further copolymerizable termonomers it is possible to make use, for example, of aromatic vinylmonomers, preferably styrene, a-methylstyrene and vinylpyridine, fluorine-containing vinylmonomers, preferably fluoroethyl vinyl ether, fluoropropyl vinyl ether, 0- fluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene and tetrafluoroethylene, or else copolymerizable anti-ageing monomers, preferably N-(4-anilinophenyl)acrylamide, N-(4- anilinophenyl)methacrylamide, N-(4-anilinophenyl)cinnamides, N-(4-anilinophenyl)crotonamide, N-phenyl-4-(3-vinylbenzyloxy)aniline and N-phenyl-4-(4-vinylbenzyloxy)aniline, and also non- conjugated dienes, such as 4-cyanocyclohexene and 4-vinylcyclohexene, or else alkynes, such as 1- or 2-butyne.

Alternatively, as further copolymerizable termonomers, it is possible to use copolymerizable termonomers containing carboxyl groups, examples being α, β -unsaturated monocarboxylic acids, their esters, their amides, α, β -unsaturated dicarboxylic acids, their monoesters or diesters, or their corresponding anhydrides or amides.

As α,β-unsaturated monocarboxylic acids it is possible with preference to use acrylic acid and methacrylic acid.

It is also possible to employ esters of the α,β-unsaturated monocarboxylic acids, preferably their alkyl esters and alkoxyalkyl esters. Preference is given to the alkyl esters, especially CpCig alkyl esters, of the α,β-unsaturated monocarboxylic acids. Particular preference is given to alkyl esters, especially CpCig alkyl esters, of acrylic acid or of methacrylic acid, more particularly methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, - - n-dodecyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate. Also preferred are alkoxyalkyl esters of the α,β-unsaturated monocarboxylic acids, more preferably alkoxyalkyl esters of acrylic acid or of methacrylic acid, more particular C2-C12 alkoxyalkyl esters of acrylic acid or of methacrylic acid, very preferably methoxymethyl acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and methoxymethyl (meth)acrylate. Use may also be made of mixtures of alkyl esters, such as those mentioned above, for example, with alkoxyalkyl esters, in the form of those mentioned above, for example. Use may also be made of cyanoalkyl acrylates and cyanoalkyl methacrylates in which the C atom number of the cyanoalkyl group is 2-12, preferably a-cyanoethyl acrylate, β-cyanoethyl acrylate and cyanobutyl methacrylate. Use may also be made of hydroxyalkyl acrylates and hydroxyalkyl methacrylate in which the C atom number of the hydroxyalkyl groups is 1-12, preferably 2-hydroxyethyl acrylate, 2- hydroxyethyl methacrylate and 3-hydroxypropyl acrylate; use may also be made of fluorine- substituted benzyl-group-containing acrylates or methacrylates, preferably fluorobenzyl acrylates, and fluorobenzyl methacrylate. Use may also be made of acrylates and methacrylates containing fluoroalkyl groups, preferably trifluoroethyl acrylate and tetrafluoropropyl methacrylate. Use may also be made of α,β-unsaturated carboxylic esters containing amino groups, such as dimethylaminomethyl acrylate and diethylaminoethyl acrylate.

As other copolymerizable monomers it is possible, furthermore, to use α,β-unsaturated dicarboxylic acids, preferably maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and mesaconic acid.

Use may be made, furthermore, of α,β-unsaturated dicarboxylic anhydrides, preferably maleic anhydride, itaconic anhydride, citraconic anhydride and mesaconic anhydride.

It is possible, furthermore, to use monoesters or diesters of α,β-unsaturated dicarboxylic acids.

These α,β-unsaturated dicarboxylic monoesters or diesters may be, for example, alkyl esters, preferably C1-C10 alkyl, more particularly ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl or n-hexyl esters, alkoxyalkyl esters, preferably C2-C12 alkoxyalkyl, more preferably C3-C8- alkoxyalkyl, hydroxyalkyl, preferably C1-C12 hydroxyalkyl, more preferably C2-C8 hydroxyalkyl, cycloalkyl esters, preferably C5-C12 cycloalkyl, more preferably Ce-Cn cycloalkyl, alkylcycloalkyl esters, preferably Ce-Cn alkylcycloalkyl, more preferably C7-C10 alkylcycloalkyl, aryl esters, preferably C6-C14 aryl esters, these esters being monoesters or diesters, and it also being possible, in the case of the diesters, for the esters to be mixed esters.

Particularly preferred alkyl esters of α,β-unsaturated monocarboxylic acids are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl - -

(meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, 2-propyl- heptyl acrylate and lauryl (meth)acrylate. More particularly, n-butyl acrylate is used.

Particularly preferred alkoxyalkyl esters of the α,β-unsaturated monocarboxylic acids are methoxyethyl (meth)acrylate, ethoxyethyl (meth) acrylate and methoxymethyl (meth)acrylate. More particularly, methoxyethyl acrylate is used.

Particularly preferred hydroxyalkyl esters of the α,β-unsaturated monocarboxylic acids are hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate.

Other esters of the α,β-unsaturated monocarboxylic acids that are used are additionally, for example, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, glycidyl (meth)acrylate, epoxy (meth)acrylate, N-(2-hydroxyethyl)acrylamides, N-(2-hydroxy- methyl)acrylamides and urethane (meth)acrylate.

Examples of α,β-unsaturated dicarboxylic monoesters encompass

• maleic acid monoalkyl esters, preferably monomethyl maleate, monoethyl maleate, monopropyl maleate and mono-n-butyl maleate;

• maleic acid monocycloalkyl esters, preferably monocyclopentyl maleate, monocyclohexyl maleate and monocycloheptyl maleate;

• maleic acid monoalkyl cycloalkyl esters, preferably monomethyl cyclopentyl maleate and monoethyl cyclohexyl maleate;

• maleic acid monoaryl esters, preferably monophenyl maleate;

• maleic acid monobenzyl esters, preferably monobenzyl maleate;

• fumaric acid monoalkyl esters, preferably monomethyl fumarate, monoethyl fumarate, monopropyl fumarate and mono-n-butyl fumarate;

• fumaric acid monocycloalkyl esters, preferably monocyclopentyl fumarate, monocyclohexyl fumarate and monocycloheptyl fumarate;

• fumaric acid monoalkyl cycloalkyl esters, preferably monomethyl cyclopentyl fumarate and monoethyl cyclohexyl fumarate;

• fumaric acid monoaryl esters, preferably monophenyl fumarate;

• fumaric acid monobenzyl esters, preferably monobenzyl fumarate;

• citraconic acid monoalkyl esters, preferably monomethyl citraconate, monoethyl citraconate, monopropyl citraconate and mono-n-butyl citraconate;

• citraconic acid monocycloalkyl esters, preferably monocyclopentyl citraconate, monocyclohexyl citraconate and monocycloheptyl citraconate;

• citraconic acid monoalkyl cycloalkyl esters, preferably monomethyl cyclopentyl citraconate - - and monoethyl cyclohexyl citraconate;

• citraconic acid monoaryl esters, preferably monophenyl citraconate;

• citraconic acid monobenzyl esters, preferably monobenzyl citraconate;

• itaconic acid monoalkyl esters, preferably monomethyl itaconate, monoethyl itaconate, monopropyl itaconate and mono-n-butyl itaconate;

• itaconic acid monocycloalkyl esters, preferably monocyclopentyl itaconate, monocyclohexyl itaconate and monocycloheptyl itaconate;

• itaconic acid monoalkyl cycloalkyl esters, preferably monomethyl cyclopentyl itaconate and monoethyl cyclohexyl itaconate;

· itaconic acid monoaryl esters, preferably monophenyl itaconate;

• itaconic acid monobenzyl esters, preferably monobenzyl itaconate.

• Mesaconic acid monoalkyl esters, preferably mesaconic acid monoethyl esters;

As α,β-unsaturated dicarboxylic diesters it is possible to use the analogous diesters based on the abovementioned monoester groups, and the ester groups may also be chemically different groups.

It is further possible, as further copolymerizable monomers, to use free-radically polymerizable compounds which contain per molecule two or more olefinic double bonds. Examples of such di- or polyunsaturated compounds are di- or polyunsaturated acrylates, methacrylates or itaconates of polyols, such as, for example, 1,6-hexanediol diacrylate (HDODA), 1,6-hexanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate, triethylene glycol diacrylate, butane- 1,4-diol diacrylate, propane- 1,2-diol diacrylate, butane-l,3-diol dimethacrylate, neopentylglycol diacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolethane diacrylate, trimethylolethane dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate (TMPTMA), glyceryl diacrylate and triacrylate, pentaerythritol di-, tri- and tetraacrylate or -methacrylate, dipentaerythritol terra-, penta- and hexa-acrylate or -methacrylate or -itaconate, sorbitol tetraacrylate, sorbitol hexamethacrylate, diacrylates or dimethacrylates or 1 ,4-cyclohexanediol, 1 ,4-dimethylolcyclohexane, 2,2-bis(4-hydroxyphenyl)propane, of polyethylene glycols or of oligoesters or oligourethanes having terminal hydroxyl groups. As polyunsaturated monomers it is also possible to use acrylamides, such as, for example, methylenebisacrylamide, hexamethylene-

1,6-bisacrylamide, diethylenetriaminetrismethacrylamide, bis(methacrylamidopropoxy)ethane or 2- acrylamidoethyl acrylate. Examples of polyunsaturated vinyl compounds and allyl compounds are divinylbenzene, ethylene glycol divinyl ether, diallyl phthalate, allyl methacrylate, diallyl maleate, triallyl isocyanurate or triallyl phosphate.

When termonomers of this kind are employed it is possible with advantage successfully to take the polymerization to high conversions and at the same time to prepare nitrile rubbers which have a - - comparatively higher average molecular weight Mw (weight average) and/or Mn (number average), and yet are gel-free.

The proportions of conjugated diene and α,β-unsaturated nitrile in the NBR polymers may vary within wide ranges. The proportion of or the sum of the conjugated dienes is typically in the range from 40 to 90% preferably in the range from 50 to 85%, by weight, based on the overall polymer. The proportion of or the sum of the α,β-unsaturated nitriles is typically 10 to 60%, preferably 15 to 50%), by weight, based on the overall polymer. The proportions of the monomers add up in each case to 100%> by weight. The additional monomers, depending on the nature of the termonomer or termonomers, may be present in amounts of 0%> to 40%> by weight, based on the overall polymer. In this case, corresponding proportions of the conjugated diene or dienes and/or of the α,β-unsaturated nitrile or nitriles are replaced by the proportions of the additional monomers, with the proportions of all the monomers adding up in each case to 100%> by weight.

If esters of (meth)acrylic acid are used as additional monomers, they are usually used in amounts of from 1 to 25% by weight.

If α,β-unsaturated monocarboxylic or dicarboxylic acids are used as additional monomers, they are usually used in amounts of less than 10% by weight. The nitrogen content of the nitrile rubbers of the invention is determined by the Kjeldahl method in accordance with DIN 53 625. Owing to the content of polar comonomers, the nitrile rubbers are usually soluble in methyl ethyl ketone to an extent of > 85% by weight at 20°C.

The nitrile rubbers have Mooney viscosities (ML (1+4 @100°C)) of from 10 to 150, preferably from 20 to 100, Mooney units. The Mooney viscosity (ML (1+4 @100°C)) is determined at 100°C by means of a shear disc viscometer in accordance with DIN 53523/3 or ASTM D 1646.

The glass transition temperatures of the optionally hydrogenated nitrile rubbers of the invention are situated in the range from -70°C to +20°C, preferably in the -60°C to 10° range.

Preference is given to nitrile rubbers according to the invention which comprise repeating units of acrylonitrile, 1,3-butadiene and optionally of one or more further copolymerizable monomers. Preference is likewise given to nitrile rubbers having repeating units of acrylonitrile, 1,3-butadiene and one or more α,β-unsaturated monocarboxylic or dicarboxylic acids, their esters or amides, and in particular repeating units of an alkylester of an α,β-unsaturated carboxylic acid, very particularly preferably of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate or lauryl (meth) aery late. - -

The preparation of such nitrile rubbers is performed by emulsion-polymerization of the abovementioned monomers which is adequately known to those skilled in the art and is comprehensively described in the polymer literature. Nitrile rubbers which can be used for the purposes of the invention are also commercially available, e.g. as products from the product range of the trade names Perbunan® and Krynac® from Lanxess Deutschland GmbH.

Prior to being subjected to the process of the present invention the nitrile rubbers can also be subjected to a metathesis reaction to lower the molecular weight which is well-known in the art and described in scientific literature and patents (e.g. US 2003/0088035 A and US 2004/0132891 A).

Nitrile rubbers to be subjected to the present process which have not undergone a methathesis reaction typically have a Mooney viscosity (ML 1+4 at 100°C) in the range from 30 to 70, preferably from 30 to 50. This corresponds to a weight average molecular weight Mw in the range 200,000 - 500,000, preferably in the range 200,000 - 400,000. The nitrile rubbers used also have a polydispersity PDI = Mw/Mn, where Mw is the weight average molecular weight and Mn is the number average molecular weight, in the range 2.0 - 6.0 and preferably in the range 2.0 - 4.0.

Nitrile rubbers to be subjected to the present process which have previously undergone a methathesis reaction typically have a Mooney viscosity (ML 1+4 at 100°C) in the range from 1 to 50, preferably from 1 to 30. This corresponds to a weight average molecular weight Mw in the range 25,000 - 250,000, preferably in the range 50,000 - 150,000. These nitrile rubbers typically have a polydispersity PDI = Mw/Mn, where Mw is the weight average molecular weight and Mn is the number average molecular weight, in the range of 1.5 to 5.0 and preferably in the range of from 1.5 to 3.5.

Hydrogenated nitrile butadiene rubbers:

The term hydrogenated nitrile butadiene rubbers or "HNBR" for short is intended to mean all aforementioned nitrile rubbers which have been subjected to hydrogenation. "Hydrogenated" in the present invention is intended to characterizse nitrile rubbers in which the C=C double bonds are partly or completely hydrogenated selectively. Preferred hydrogenated nitrile rubbers are those with a degree of hydrogenation, based on the C=C double bond originating from the conjugated diene, of at least 75, preferably at least 95, more preferably at least 98%. The degree of hydrogenation can be determined by NMR and IR spectroscopy.

For hydrogenation the nitrile rubber obtained from emulsion polymerization is converted into a solid rubber. The conversion of the nitrile rubber latex into a solid rubber is carried out by the methods known to the person skilled in the art. The nitrile rubber, from which impurities have been - - removed, is subsequently either dissolved in an organic solvent, if the impurities were removed from it by the purification methods known to the person skilled in the art, such as precipitation or coagulation and subsequent washing, or the retentate solution obtained by the method according to the present invention, which contains the dissolved and purified nitrile butadiene rubber, directly has a transition metal catalyst suitable for the hydrogenation added to it, and is hydrogenated.

The hydrogenation of nitrile rubber is well known to a person skilled in the art from US-A- 3,700,637; 4,464,515 and DE A3-046,008, DE A3-227,650 and DE A3-329,974. NBR and HNBR are also collectively referred to as (H)NBR in this application unless indicated otherwise.

Process pursuant to the invention:

The inventive process allows at the same time the purification of nitrile rubbers as well as hydrogenated nitrile rubber in various aspects. It is possible to remove the following types of components (1) to (3) simultaneously:

(1) ruthenium, osmium and rhodium catalysts used for catalysing the metathesis and/or hydrogenation reaction(s) and any degradation products.

(2) iron containing residues and degradation products thereof, and

(3) compounds used either in the emulsion polymerisation process of the nitrile rubber and the optional subsequent metathesis reaction and the subsequent optional hydrogenation process or any degradation products thereof, including but not being limited to fatty acid emulsifiers and salts thereof, salt complexes of Na, K, Mg and Fe, residual nitrile rubber molecular weight modifiers, residual acrylonitrile, defoamers and anti foaming agents.

Such broad purification has not been disclosed anywhere in the prior art and is surprising in its scope, although considerable academic attention has already been given to the ionic liquids covering various general olefin processes such as olefin hydrogenation (Dyson et al., J. of Organometallic Chem., 2005, 690, p. 3552), metathesis of low molecular weight compounds (Tang et al., Tetrahedron Letters, 2006, 47, 2921), hydroformylation (Esterhuysen et al., J. of the Chemical Society - Dalton Transactions, 2002, 1132), carbonylation (Kollar et al., Chem. Communications, 2000, 1695), carboxylation (Arai et al., Catalysis Communications, 2004, 5, 83) and as new solutions for transition metal catalysis (Wasserscheid et al., Angew. Chem. Int. Ed., 2000, 39, 3772).

Similarly, the use of ionic liquids has been used for documented and historical organic and inorganic reactions such as Diels-Alder (Oh et al, Tetrahedron Letters, 2003, 44, 6465), Friedel- - -

Crafts alkylations (Garcia et al., Catalysis Letters, 2002, 78, 115), Mannich-type reactions (Loh et al., Tetrahedron Letters, 2003, 44, 2405) and Heck arylation reactions (Muzart et al, J. of Organometallic Chem., 2001, 634, 153). Ionic liquids have also been used to behave as purification reagents. Haag et al. (Angew. Chem. Int. Ed., 2002, 41, 3964) have taught the benefits of liquid-liquid phase separation with ionic liquids due to the fact that ionic liquids are not miscible with the majority of organic solvents. This benefit allows for impurities found in the organic phase to be easily removed through interaction, washing and/or stirring with an ionic liquid.

However, even in view of these numerous prior art references it was unforeseeable that the removal of the various impurities contained in nitrile rubber or hydrogenated nitrile rubber could be successfully removed by contacting said polymer with an ionic liquid, as the solutions of nitrile rubber as well as hydrogenated nitrile rubber are highly viscous due to the high molecular weight of the polymers and any type of mixing is therefore very difficult and challenging, let alone the removal of impurities.

The inventive use of an ionic liquid allows a facilitated separation between the catalyst, catalyst degradation products and the main product after the end of the reaction and makes it additionally possible to reuse the catalytic system.

The elastomers obtained by the method according to the invention are distinguished by many advantages. They exhibit less mould contamination in injection-molding applications, and the purified elastomers may be used in contact with food and in the medical field owing to the low incidence of contamination. The purified elastomers can be used for insulation in the electronics field, since only reduced amounts of ionic impurities which can conduct current remain, and environmentally unfriendly substances are not left behind in the event of burning. Owing to these properties, because of the low impurity level, these elastomers are suitable for use in the cosmetic and medical fields, the food-contact and electronics sectors and in the rubber industry. Additional advantages result from the cost saving in subsequent refining processes, for example hydrogenation and metatheses, by saving on catalyst and lower maintenance costs owing to lower corrosion potentials. The method is furthermore straightforward, and it can readily be carried out fully continuously even on an industrial scale. Components (1) which may be removed according to the present invention represent

ruthenium catalysts and degradation products thereof,

rhodium catalysts and degradation products thereof, and

osmium catalysts and degradation products thereof. - -

The aforementioned ruthenium, osmium and rhodium catalysts as well as the respective degradation products thereof are either used during the emulsion polymerization of the nitrile rubber, the optional metathesis reaction and/or the optional subsequent hydrogenation reaction. One preferred catalyst used during hydrogenation of nitrile rubber is a rhodium- or ruthenium- containing catalyst, more preferably a catalyst of the general formula

(R¹⁰ _mB)i M X_n ,

where M is ruthenium or rhodium, the radicals R¹⁰ are identical or different and are each a CpCg- alkyl group, a C pCg-cycloalkyl group, a C6-Ci₅-aryl group or a C₇-Ci₅-aralkyl group. B is phosphorus, arsenic, sulphur or a sulphoxide group S=0, X is hydrogen or an anion, preferably halogen and particularly preferably chlorine or bromine, 1 is 2, 3 or 4, m is 2 or 3 and n is 1 , 2 or 3, preferably 1 or 3. Preferred catalysts are tris(triphenylphosphine)rhodium(I) chloride, tris(tri- phenylphosphine)rhodium(III) chloride and tris(dimethyl sulphoxide)rhodium(III) chloride and also tetrakis(triphenylphosphine)rhodium hydride of the formula (C6H₅)3P)₄RhH and the corresponding compounds in which the triphenylphosphine has been completely or partly replaced by tricyclohexylphosphine.

Further catalysts to be covered by component (1) have the general formula (A),

L

X¹ l ^R (A) where

M is osmium or ruthenium,

X¹ and X² are identical or different and are two ligands, preferably anionic ligands,

L are identical or different ligands, preferably uncharged electron donors,

R are identical or different and are each hydrogen, alkyl, preferably Ci-C3o-alkyl, cycloalkyl, preferably C3-C2o-cycloalkyl, alkenyl, preferably C2-C2o-alkenyl, alkynyl, preferably C2-C2o-alkynyl, aryl, preferably C6-C24-aryl, carboxylate, preferably C1-C20- carboxylate, alkoxy, preferably Ci-C2o-alkoxy, alkenyloxy, preferably C2-C20- alkenyloxy, alkynyloxy, preferably C2-C2o-alkynyloxy, aryloxy, preferably C6-C24- aryloxy, alkoxycarbonyl, preferably C2-C2o-alkoxycarbonyl, alkylamino, preferably Ci-C3o-alkylamino, alkylthio, preferably Ci-C3o-alkylthio, arylthio, preferably C6-C24- arylthio, alkylsulphonyl, preferably Ci-C2o-alkylsulphonyl, or alkylsulphinyl, preferably Ci-C2o-alkylsulphinyl, where these groups may in each case optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl moities or, as an alternative, the two groups R together with the common carbon atom to which they are - - bound are bridged to form a cyclic structure which can be aliphatic or aromatic in nature, may be substituted and may contain one or more heteroatoms.

Various representatives of the catalysts of the formula (A) are known in principle, e.g. from WO-A-96/04289 and WO-A-97/06185.

In preferred catalysts of the general formula (A), one group R is hydrogen and the other group R is Ci-C₂o-alkyl, C3-Cio-cycloalkyl, C₂-C₂o-alkenyl, C₂-C₂o-alkynyl, C6-C24-aryl, Ci-C₂o-carboxylate, Ci-C₂o-alkoxy, C₂-C₂o-alkenyloxy, C₂-C₂o-alkynyloxy, C6-C24-aryloxy, C₂-C₂o-alkoxycarbonyl, Ci-C3o-alkylamino, Ci-C3o-alkylthio, C6-C24-arylthio, Ci-C₂o-alkylsulphonyl or C₁-C₂₀- alkylsulphinyl, where these moiety may in each case be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl groups.

In the catalysts of the general formula (A), X¹ and X² are identical or different and are two ligands, preferably anionic ligands.

X¹ and X² can be, for example, hydrogen, halogen, pseudohalogen, straight-chain or branched Ci-C3o-alkyl, C6-C24-aryl, Ci-C₂o-alkoxy, C6-C24-aryloxy, C3-C₂o-alkyldiketonate C6-C24- aryldiketonate, Ci-C₂o-carboxylate, Ci-C₂o-alkylsulphonate, C6-C24-arylsulphonate, C₁-C₂₀- alkylthiol, C6-C24-arylthiol, Ci-C₂o-alkylsulphonyl or Ci-C₂o-alkylsulphinyl.

X¹ and X² can also be substituted by one or more further groups, for example by halogen, preferably fluorine, Ci-Cio-alkyl, Ci-Cio-alkoxy or C6-C24-aryl, where these groups, too, may once again be substituted by one or more substituents selected from the group consisting of halogen, preferably fluorine, Ci-C₅-alkyl, Ci-C₅-alkoxy and phenyl.

In a preferred embodiment, X¹ and X² are identical or different and are each halogen, in particular fluorine, chlorine, bromine or iodine, benzoate, Ci-C₅-carboxylate, Ci-C₅-alkyl, phenoxy, C₁-C5- alkoxy, Ci-C₅-alkylthiol, C6-C24-arylthiol, C6-C24-aryl or Ci-C₅-alkylsulphonate.

In a particularly preferred embodiment, X¹ and X² are identical and are each halogen, in particular chlorine, CF₃COO, CH₃COO, CFH₂COO, (CH₃)₃CO, (CF₃)₂(CH₃)CO, (CF₃)(CH₃)₂CO, PhO (phenoxy), MeO (methoxy), EtO (ethoxy), tosylate (p-CH3-C₆H4-S0₃), mesylate (CH3-SO3) or CF₃ S O₃ (trifluoromethanesulphonate) .

In the general formula (A), the symbols L represent identical or different ligands and are preferably uncharged electron donating ligand. - -

The two ligands L can, for example, be, independently of one another, a phosphine, sulphonated phosphine, phosphate, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, sulfonate, sulfoxide, carboxyl, nitrosyl, pyridine, thioether, imidazoline or imidazolidine (the latter two also being jointly referred to as "Im" ligand(s)).

The term "phosphinite" includes, for example, phenyl diphenylphosphinite, cyclohexyl dicyclohexylphosphinite, isopropyl diisopropylphosphinite and methyl diphenylphosphinite.

The term "phosphite" includes, for example, triphenyl phosphite, tricyclohexyl phosphite, tri-tert- butyl phosphite, triisopropyl phosphite and methyl diphenyl phosphite.

The term "stibine" includes, for example, triphenylstibine, tricyclohexylstibine and trimethylstibine.

The term "sulfonate" includes, for example, trifluoromethanesulphonate, tosylate and mesylate.

The term "sulfoxide" includes, for example, (CH₃)₂S(=0) and (C₆H₅)₂S=0.

The term "thioether" includes, for example, CH₃SCH₃, C₆H₅SCH₃, CH₃OCH₂CH₂SCH₃ and tetrahydrothiophene.

For the purposes of the present application, the term "pyridine" is used as a collective term for all nitrogen-containing ligands as are mentioned by, for example, Grubbs in WO-A-03/011455. Examples are: pyridine, picolines (including α-, β- and γ-picoline), lutidines (including 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-lutidine), collidine (2,4,6-trimethylpyridine), trifluoromethylpyridine, phenylpyridine, 4-(dimethylamino)pyridine, chloropyridines, bromopyridines, nitropyridines, quinoline, pyrimidine, pyrrole, imidazole and phenylimidazole.

In a preferred embodiment catalysts of general formula (A) are used in which one or both of ligands L represent an imidazoline or imidazolidine ligand (also jointly referred to as "Im"- ligand in this application unless indicated otherwise), having a structure of general formulae (Ila) or (lib), wherein the meaning of L can be identical or different in case both ligands L have a structure according to (Ila) or

(Ila) (Mb)

where - -

R⁸' R⁹, R¹⁰ and R¹¹ are identical or different and represent hydrogen, straight-chain or branched Cp C₃₀-alkyl, C₃-C₂o-cycloalkyl, C₂-C₂o-alkenyl, C₂-C₂o-alkynyl, C₆-C₂₄-aryl, C₇-C₂₅-alkaryl, C₂-C₂₀ heteroaryl, C₂-C₂o heterocyclyl, Ci-C₂o-alkoxy, C₂-C₂o-alkenyloxy, C₂-C₂o-alkynyloxy, C6-C₂o- aryloxy, C₂-C₂₀-alkoxycarbonyl, C_rC₂₀-alkylthio, C₆-C₂₀-arylthio, -Si(R)₃, -0-Si(R)₃, -0-C(=0)R, C(=0)R, -C(=0)N(R)₂, -NR-C(=0)-N(R)₂, -S0₂N(R)₂ , -S(=0)R, -S(=0)₂R, -0-S(=0)₂R, halogen, nitro or cyano, wherein in all above occurences relating to the meanings of R⁸' R⁹, R¹⁰ and R¹¹ the group R is identical or different and represents hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl. If appropriate, one or more of R⁸, R⁹, R¹⁰, and R¹¹ can independently of one another, be substituted by one or more substituents, preferably straight-chain or branched Ci-Cio-alkyl, C₃-Cg-cycloalkyl, CpCio-alkoxy or C6-C₂4-aryl, C₂-C₂o heteroaryl, C₂-C₂o heterocyclic, and a functional group selected from the group consisting of hydroxy, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen, where these abovementioned substituents, to the extent chemically possible, may in turn be substituted by one or more substituents, preferably selected from the group consisting of halogen, in particular chlorine or bromine, Ci-C₅-alkyl, Ci-C₅-alkoxy and phenyl. Merely in the interest of clarity, it may be added that the structures of the imidazoline and imidazolidine ligand depicted in the general formulae (Ila) and (lib) in the present patent application are equivalent to the structures (Ha') and (lib') which are frequently also found in the literature for this imidazoline and imidazolidine ligand, respectively, and emphasize the carbene character of the imidazoline and imidazolidine. This applies analogously to the associated preferred structures (Illa)-(IIIu) depicted below.

In a preferred embodiment of the catalysts of the general formula (A),

R⁸ and R⁹ are each identical or different and represent hydrogen, C6-C₂4-aryl, straight-chain or branched Ci-Cio-alkyl, or form a cycloalkyl or aryl structure together with the carbon atoms to which they are bound.

More preferably

R⁸ and R⁹ are identical and are selected from the group consisting of hydrogen, methyl, propyl, butyl and phenyl. _ -

The preferred and more preferred meanings of R⁸ and R⁹ may be substituted by one or more further substituents selected from the group consisting of straight-chain or branched Ci-Cio-alkyl or Cp Cio-alkoxy, C3-Cg-cycloalkyl, C6-C24-aryl, and a functional group selected from the group consisting of hydroxy, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen, wherein all these substituents may in turn be substituted by one or more substituents, preferably selected from the group consisting of halogen, in particular chlorine or bromine, C1-C5- alkyl, Ci-C₅-alkoxy and phenyl.

R¹⁰ and R¹¹ are identical or different and preferably represent straight-chain or branched C1-C10- alkyl, C3-Cio-cycloalkyl, C6-C24-aryl, particularly preferably phenyl, Ci-Cur alkylsulfonate, C6-Cio-arylsulfonate.

More preferably

R¹⁰ and R¹¹ are identical and are selected from the group consisting of i-propyl, neopentyl, adamantyl, phenyl, 2,6-diisopropylphenyl, 2,6-dimethylphenyl, or 2,4,6- trimethylphenyl.

The preferred meanings of R¹⁰ and R¹¹ may be substituted by one or more further substituents selected from the group consisting of straight-chain or branched Ci-Cio-alkyl or Ci-Cio-alkoxy, C3- Cg-cycloalkyl, C6-C24-aryl, and a functional group selected from the group consisting of OH, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen, wherin all these substituents may in turn be substituted by one or more substituents, preferably selected from the group consisting of halogen, in particular chlorine or bromine, Ci-C₅-alkyl, Ci-C₅-alkoxy and phenyl.

Particularly preferred are catalysts of general formula (A) in which one or both of ligands L represent imidazoline and imidazolidine ligands having the structures (Ilia) to (IIIu), where "Ph" means in each case phenyl, "Bu" means butyl, "Mes" represents in each case 2,4,6-trimethylphenyl, "Dipp" means in all cases 2,6-diisopropylphenyl and "Dimp" means 2,6-dimethylphenyl, and wherein the meaning of L can be identical or different in case both ligands L in general formula (A) have a structure according to (Ilia) to (IIIu), - -

Bu Bu Bu^ ^Bu

Ph^ ^Ph

I— I

Dipp

Dipp J Dipp Dipp Dipp - - ^oipp

(lllm) (Illn)

Dimp

(lllp) (ll lq) (ll lr)

(Ills) (lilt) (l llu)

In a further preferred embodiment of catalyst (A) one or both of the ligands L may have the meaning of general formulae (lie) or (lid), wherein the meaning of L can be identical or different in case both ligands L have a structure according to (lie) or (lid),

(lie) (Ild)

wherein

R⁸, R⁹ and R¹⁰ may have all general, preferred, more preferred and most preferred meanings as defined above in relation to general formulae (Ila) and (lib), and - -

R , R and R are identical or different and may represent alkyl, cycloalkyl, alkoxy, aryl, aryloxy, or a heterocyclic group.

In general formulae (lie) and (lid) R⁸, R⁹, R¹⁰, R¹⁵, R¹⁶ and R¹⁷ may also be substituted by one or more further, identical or different substituents selected from the group consisting of straight-chain or branched Ci-C₅-alkyl, in particular methyl, Ci-C₅-alkoxy, aryl and a functional group selected from the group consisting of hydroxy, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen.

In a more preferred embodiment the ligands L has the general formula (lid) wherein

R¹⁵, R¹⁶ and R¹⁷ are identical or different, even more preferably identical, and can represent d-

C₂o alkyl, C₃-C₈-cycloalkyl, C1-C20 alkoxy, C₆-C₂o aryl, C₆-C₂o aryloxy, C₂-C₂o heteroaryl or a C₂-C₂o heterocyclic group.

In an even more preferred embodiment the ligand L has the general formula (lid) wherein

R¹⁵, R¹⁶ and R¹⁷ are identical and each selected from the group consisting of methyl, ethyl, n- propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1 -methylbutyl, 2- methylbutyl, 3 -methylbutyl, neopentyl, 1 -ethylpropyl, n-hexyl, neophenyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl cyclooctyl, phenyl, biphenyl, naphthyl, phenanthrenyl, anthracenyl, tolyl, 2,6-dimethylphenyl, and trifluoromethyl.

In case one or both of the ligand L possess general formula (lid) it most preferably represents PPh₃, P(p-Tol)₃, P(o-Tol)₃, PPh(CH₃)₂, P(CF₃)₃, P(p-FC₆H₄)₃, P(p-CF₃C₆H₄)₃, P(C₆H₄-S0₃Na)₃, P(CH₂C₆H₄-S0₃Na)₃, P(isopropyl)₃, P(CHCH₃(CH₂CH₃))₃, P(cyclopentyl)₃, P(cyclohexyl)₃, P(neopentyl)₃ or P(neophenyl)₃.

The following catalysts with structures (IV) (Grubbs I catalyst) and (V) (Grubbs II catalyst) shall also be covered by component (1), where Cy is cyclohexyl.

Mes— N N— Mes

- -

where

X¹, X² and L can have the same general, preferred and particularly preferred meanings as in the general formula (A),

n is 0, 1 or 2,

m is 0, 1 , 2, 3 or 4 and

R' are identical or different and are alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl radicals which may in each case be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl.

A further catalyst of general formula (Al) is the catalyst of the formula (VI) below, where Mes is in each case 2,4,6-

This catalyst which is also referred to in the literature as "Nolan catalyst" is known, for example, from WO-A-2004/112951.

Further catalysts to be covered by component (1) are the catalysts of the general formula (B),

where

M is ruthenium or osmium,

X¹ and X² are identical or different and are anionic ligands,

R" are identical or different and are organic moieties,

Im is a substituted or unsubstituted imidazoline or imidazolidine ligand and

An is an anion. - -

The catalysts of the general formula (B) are known in principle (see, for example, Angew. Chem. Int. Ed. 2004, 43, 6161-6165).

X¹ and X² in the general formula (B) can have the same general, preferred and particularly preferred meanings as in the formula (A).

The imidazoline or imidazolidine ligand usually has a structure of the general formulae (Ila) or (lib) which have been mentioned above for the catalyst of general formula (A) and can have all the structures mentioned there as preferred, in particular those of the formulae (Illa)-(IIIu).

In general formula (B) R" are identical or different and are each a straight-chain or branched Cp C3o-alkyl, C₅-C3o-cycloalkyl or aryl, where the Ci-C3o-alkyl moiety may be interrupted by one or more double or triple bonds or one or more heteroatoms, preferably oxygen or nitrogen.

Aryl is an aromatic radical having from 6 to 24 skeletal carbon atoms. As preferred monocyclic, bicyclic or tricyclic carbocyclic aromatic moieties having from 6 to 10 skeletal carbon atoms, mention may be made by way of example of phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.

Preference is given to R" in the general formula (B) being identical and each being phenyl, cyclohexyl, cyclopentyl, isopropyl, o-tolyl, o-xylyl or mesityl.

Further catalysts to be covered by component (1) are the catalysts of the general formula (C),

where

M is ruthenium or osmium,

14

R^1J and R are each, independently of one another, hydrogen, Ci-C2o-alkyl, C2-C2o-alkenyl,

C2-C2o-alkynyl, C6-C24-aryl, Ci-C2o-carboxylate, Ci-C2o-alkoxy, C2-C2o-alkenyloxy, C2-C2o-alkynyloxy, C6-C24-aryloxy, C2-C2o-alkoxycarbonyl, Ci-C2o-alkylthio, Ci-C2o-alkylsulphonyl or Ci-C2o-alkylsulphinyl,

X is an anionic ligand,

2

L is an uncharged π-bonded ligand which may either be monocyclic or polycyclic, - - is a ligand selected from the group consisting of phosphines, sulphonated phosphines, fluorinated phosphines, functionalized phosphines having up to three aminoalkyl, ammonioalkyl, alkoxyalkyl, alkoxycarbonylalkyl, hydrocarbonylalkyl, hydroxyalkyl or ketoalkyl groups, phosphites, phosphinites, phosphonites, phosphinamines, arsines stibines, ethers, amines, amides, imines, sulphoxides, thioethers and pyridines,

is a noncoordinating anion and

is 0, 1, 2, 3, 4 or 5.

Further catalysts to be covered by component (1) are the catalysts of the general formula (D),

L

I R¹⁹

^ M=C=C (D)

X^{l /} V

where

M is ruthenium or osmium,

X¹ and X² are identical or different and are anionic ligands which can have all meanings of

X¹ and X² mentioned in the general formulae (A) and (B),

the symbols L represent identical or different ligands which can have all general and preferred meanings of L mentioned in the general formulae (A) and (B),

R¹⁹ and R²⁰ are identical or different and are each hydrogen or substituted or unsubstituted alkyl.

Further catalysts to be covered by component (1) are the catalysts of the general formula (E), (F) and (G)

(F) (G) is osmium or ruthenium,

are identical or different and are two ligands, preferably anionic ligands, is a ligand, preferably an uncharged electron donor,

are identical or different and are uncharged electron donors,

are each, independently of one another, hydrogen alkyl, cycloalkyl, alkenyl, alkynyl, aryl, carboxylate, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, alkylsulphonyl or alkylsulphinyl which are - - in each case substituted by one or more substituents selected from among alkyl, halogen, alkoxy, aryl or heteroaryl.

The catalysts of the general formulae (E), (F), and (G) are known in principle, e.g. from WO 2003/011455 Al, WO 2003/087167 A2, Organometallics 2001, 20, 5314 and Angew. Chem. Int. Ed. 2002, 41, 4038. The catalysts are commercially available or can be synthesized by the preparative methods indicated in the abovementioned literature references.

In the catalysts of the general formulae (E), (F), and (G) can be used in which Z¹ and Z² are identical or different and are uncharged electron donors. These ligands are usually weakly coordinating. The ligands are typically optionally substituted heterocyclic groups. These can be five- or six-membered monocyclic groups having from 1 to 4, preferably from 1 to 3 and particularly preferably 1 or 2, heteroatoms or bicyclic or polycyclic structures made up of 2, 3, 4 or 5 five- or six-membered monocyclic groups of this type, where all the abovementioned groups may in each case optionally be substituted by one or more alkyl, preferably Ci-Cio-alkyl, cycloalkyl, preferably C3-Cg-cycloalkyl, alkoxy, preferably CpCio-alkoxy, halogen, preferably chlorine or bromine, aryl, preferably C6-C24-aryl, or heteroaryl, preferably C₅-C23-heteroaryl, radicals which may in turn each be substituted by one or more moieties, preferably selected from the group consisting of halogen, in particular chlorine or bromine, Ci-C₅-alkyl, Ci-C₅-alkoxy and phenyl.

Examples of Z¹ and Z² encompass nitrogen-containing heterocycles such as pyridines, pyridazines, bipyridines, pyrimidines, pyrazines, pyrazolidines, pyrrolidines, piperazines, indazoles, quinolines, purines, acridines, bisimidazoles, picolylimines, imidazolines, imidazolidines and pyrroles.

Z¹ and Z² can also be bridged to one another to form a cyclic structure. In this case, Z¹ and Z² form a single bidentate ligand.

In the catalysts of the general formulae (E), (F), and (G) L can have the same general, preferred and particularly preferred meanings as L in the general formula (A) and (B).

In the catalysts of the general formulae (E), (F), and (G) R²¹ and R²² are identical or different and are each alkyl, preferably Ci-C3o-alkyl, particularly preferably Ci-C2o-alkyl, cycloalkyl, preferably C3-C2o-cycloalkyl, particularly preferably C3-Cg-cycloalkyl, alkenyl, preferably C2-C2o-alkenyl, particularly preferably C2-Ci6-alkenyl, alkynyl, preferably C2-C2o-alkynyl, particularly preferably

C2-Ci6-alkynyl, aryl, preferably C6-C24-aryl, carboxylate, preferably Ci-C2o-carboxylate, alkoxy, preferably Ci-C2o-alkoxy, alkenyloxy, preferably C2-C2o-alkenyloxy, alkynyloxy, preferably C2- C2o-alkynyloxy, aryloxy, preferably C6-C24-aryloxy, alkoxycarbonyl, preferably C2-C20- - - alkoxycarbonyl, alkylamino, preferably Ci-C3o-alkylamino, alkylthio, preferably Ci-C3o-alkylthio, arylthio, preferably C6-C24-arylthio, alkylsulphonyl, preferably Ci-C2o-alkylsulphonyl, or alkylsulphinyl, preferably Ci-C2o-alkylsulphinyl, where the abovementioned substituents may be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl moieties.

In the catalysts of the general formulae (E), (F), and (G) X¹ and X² are identical or different and can have the same general, preferred and particularly preferred meanings as indicated above for X¹ and X² in the general formula (A). Further catalysts to be covered by component (1) are those of general formulae (E), (F), and (G) in which

M is ruthenium,

X¹ and X² are both halogen, in particular chlorine,

R¹ and R² are identical or different and are five- or six-membered monocyclic groups having from 1 to 4, preferably from 1 to 3 and particularly preferably 1 or 2, heteroatoms or bicyclic or polycyclic structures made up of 2, 3, 4 or 5 five- or six-membered monocyclic groups of this type, where all the abovementioned groups may in each case be substituted by one or more moieties selected from the group consisting of alkyl, preferably Ci-Cio-alkyl, cycloalkyl, preferably C3-Cg-cycloalkyl, alkoxy, preferably Ci-Cio-alkoxy, halogen, preferably chlorine or bromine, aryl, preferably

C6-C24-aryl, or heteroaryl, preferably C₅-C23-heteroaryl,

Z¹ and Z² are identical or different and five- or six-membered monocyclic groups having from 1 to 4, preferably from 1 to 3 and particularly preferably 1 or 2, heteroatoms or bicyclic or polycyclic structures made up of 2, 3, 4 or 5 five- or six-membered monocyclic groups of this type, where all these abovementioned groups may in each case optionally be substituted by one or more alkyl, preferably Ci-Cio-alkyl, cycloalkyl, preferably C3-Cg-cycloalkyl, alkoxy, preferably CpCio-alkoxy, halogen, preferably chlorine or bromine, aryl, preferably C6-C24-aryl, or heteroaryl, preferably C₅-C23-heteroaryl, radicals which may in turn each be substituted by one or more moieties, preferably selected from the group consisting of halogen, in particular chlorine or bromine, Ci-C₅-alkyl, Ci-C₅-alkoxy and phenyl,

R ¹ and R²² are identical or different and are each Ci-C3o-alkyl C3-C2o-cycloalkyl, C2-G 20- alkenyl, C2-C2o-alkynyl, C6-C24-aryl, Ci-C2o-carboxylate, Ci-C2o-alkoxy, C2-C20- alkenyloxy, C2-C2o-alkynyloxy, C6-C24-aryloxy, C2-C2o-alkoxycarbonyl, C1-C30- alkylamino, Ci-C3o-alkylthio, C6-C24-arylthio, Ci-C2o-alkylsulphonyl, C1-C20- alkylsulphinyl, and

has a structure of the above-described general formula (Ila) or (lib), in particular one of the formulae (Ilia) to (IIIu). - -

A further catalyst to be covered by component (1) has the structure (XIX),

where R and R are identical or different and are each halogen, straight-chain or branched Cp C2o-alkyl, Ci-C2o-heteroalkyl, Ci-Cio-haloalkyl, Ci-Cio-alkoxy, C6-C24-aryl, preferably bromine, phenyl, formyl, nitro, a nitrogen heterocycle, preferably pyridine, piperidine or pyrazine, carboxy, alkylcarbonyl, halocarbonyl, carbamoyl, thiocarbamoyl, carbamido, thioformyl, amino, dialkylamino, trialkylsilyl or trialkoxysilyl.

The abovementioned meanings for R²³ and R²⁴ C_rC₂o-alkyl, C_rC₂o-heteroalkyl, C_rCi₀-haloalkyl, Ci-Cio-alkoxy, C6-C24-aryl, preferably phenyl, formyl, nitro, a nitrogen heterocycle, preferably pyridine, piperidine or pyrazine, carboxy, alkylcarbonyl, halocarbonyl, carbamoyl, thiocarbamoyl, carbamido, thioformyl, amino, trialkylsilyl and trialkoxysilyl may in turn each be substituted by one or more halogen, preferably fluorine, chlorine or bromine, Ci-C₅-alkyl, Ci-C₅-alkoxy or phenyl moities.

Further catalysts to be covered by component (1) have the structure (XIX a) or (XIX b), where R²³ and R²⁴ have the same meanin s as indicated in formula (XIX).

(XlXa) (XlXb)

When R²³ and R²⁴ are each bromine in formula (XlXa), the catalyst is referred to in the literature as the "Grubbs III catalyst".

Further catalysts to be covered by component (1) which come under general formulae (E), (F), and (G) have the structural formulae (XX)-(XXXII), where Mes is in each case 2,4,6-trimethylphenyl. - -

- -

Further catalysts to be covered by component (1) are catalysts (N) containing the general structural element (Nl), where the carbon atom denoted by "*" is bound via one or more double bonds to the catalyst framework l metal,

and where

_R25__R32 are identical or different and are each hydrogen, halogen, hydroxyl, aldehyde, keto, thiol,

CF₃, nitro, nitroso, cyano, thiocyano, isocyanato, carbodiimide, carbamate, thiocarbamate, dithiocarbamate, amino, amido, imino, silyl, sulphonate (-SO₃ ), -OSO₃ ^", -PO₃ ^" or OPO₃ ^" or alkyl, cycloalkyl, alkenyl, alkynyl, aryl, carboxylate, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl, alkylsulphinyl, dialkylamino, alkylsilyl or alkoxysilyl, where all these moieties can each optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents, or, as an alternative, two directly adjacent substituents from the group consisting of R²⁵-R³² together with the ring carbons to which they are bound form a cyclic group, preferably an aromatic system, by bridging or, as an alternative, R⁸ is optionally bridged to another ligand of the ruthenium- or osmium-carbene complex catalyst,

m is 0 or 1 and

A is oxygen, sulphur, C(R³³R³⁴), N-R³⁵, -C(R³⁶)=C(R³⁷)-, -C(R³⁶)(R³⁸)-C(R³⁷)(R³⁹)-, where

33 39 25 32

R -R are identical or different and can each have the same meanings as R -R . - -

In the catalysts having the structural element of the general formula (Nl) the carbon atom denoted by "*" is bound via one or more double bonds to the catalyst framework. If the carbon atom denoted by "*" is bound via two or more double bonds to the catalyst framework, these double bonds can be cumulated or conjugated.

Such catalysts (N) have been described in US-A-2009/0076226, which also discloses their preparation.

The catalysts (N) having a structural element of the general formula (Nl) include, for example, cata

(N2a) (N2b)

where

M is ruthenium or osmium,

L¹ and L² are identical or different ligands, preferably uncharged electron donors, where L can alternatively also be bridged to the radical R⁸,

n is 0, 1, 2 or 3, preferably 0, 1 or 2,

n' is 1 or 2, preferably 1, and

R -R , m and A have the same meanings as in the general formula (Nl).

In the catalysts of the general formula (N2a), the structural element of the general formula (Nl) is bound via a double bond (n = 0) or via 2, 3 or 4 cumulated double bonds (in the case of n = 1 , 2 or 3) to the central metal of the complex catalyst. In the catalysts of the general formula (N2b) suitable to be used for the catalyst systems according to the invention, the structural element of the general formula (Nl) is bound via conjugated double bonds to the metal of the complex catalyst. In both cases, the carbon atom denoted by "*" as a double bond in the direction of the central metal of the complex catalyst.

The catalysts of the general formulae (N2a) and (N2b) thus encompass catalysts in which the general structural elements (N3)-(N9) - -

are bound via the carbon atom denoted by "*" via one or more double bonds to the catalyst framework of the general formula (NlOa) or (NlOb)

(N10a) (N10b)

1 2 1 2 25 39

where X and X , L and L , n, n' and R -R have the meanings given for the general formulae (N2a) and (N2b).

The Ru- or Os-based carbene catalysts resulting thereof typically have five-fold coordination. In the structural element of the general formula (Nl),

_R25__R32 are identical or different and are each hydrogen, halogen, hydroxyl, aldehyde, keto, thiol, CF₃, nitro, nitroso, cyano, thiocyano, isocyanato, carbodiimide, carbamate, thiocarbamate, dithiocarbamate, amino, amido, imino, silyl, sulphonate (-SO₃ ), -OSO₃ ^", -PO₃ ^" or OPO₃ ^" or alkyl, preferably Ci-C2o-alkyl, in particular Ci-Ce-alkyl, cycloalkyl , preferably C3-C20- cycloalkyl, in particular C3-Cg-cycloalkyl, alkenyl, preferably C2-C2o-alkenyl, alkynyl, preferably C2-C2o-alkynyl, aryl, preferably C6-C24-aryl, in particular phenyl, carboxylate, - - preferably Ci-C2o-carboxylate, alkoxy, preferably Ci-C2o-alkoxy, alkenyloxy, preferably C2-C2o-alkenyloxy, alkynyloxy, preferably C2-C2o-alkynyloxy, aryloxy, preferably C6-C24- aryloxy, alkoxycarbonyl, preferably C2-C2o-alkoxycarbonyl, alkylamino, preferably Cp C3o-alkylamino, alkylthio, preferably Ci-C3o-alkylthio, arylthio, preferably C6-C24-arylthio, alkylsulphonyl, preferably Ci-C2o-alkylsulphonyl, alkylsulphinyl, preferably C1-C20- alkylsulphinyl, dialkylamino, preferably di(Ci-C2o-alkyl)amino, alkylsilyl, preferably Cp C2o-alkylsilyl, or alkoxysilyl, preferably Ci-C2o-alkoxysilyl, where these moities can each be optionally substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents, or, as an alternative, in each case two directly adjacent substituents from the group consisting of R²⁵-R³² together with the ring carbons to which they are bound may also form a cyclic group, preferably an aromatic system, by bridging or, as an alternative, R⁸ is optionally bridged to another ligand of the ruthenium- or osmium-carbene complex catalyst,

m is 0 or 1 and

A is oxygen, sulphur, C(R³³)(R³⁴), N-R³⁵, -C(R³⁶)=C(R³⁷)- or -C(R³⁶)(R³⁸)-C(R³⁷)(R³⁹)-, where R³³-R³⁹ are identical or different and can each have the same preferred meanings as the radicals R'-R⁸.

Ci-C6-Alkyl in the structural element of the general formula (Nl) is, for example, methyl, ethyl, n- propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl, neopentyl, 1-ethylpropyl or n-hexyl.

C3-Cg-Cycloalkyl in the structural element of the general formula (Nl) is, for example, cyclopropyl, cyclobutyl, cylopentyl, cyclohexyl, cycloheptyl or cyclooctyl.

C6-C24-Aryl in the structural element of the general formula (Nl) comprises an aromatic radical having from 6 to 24 skeletal carbon atoms. As preferred monocyclic, bicyclic or tricyclic carbocyclic aromatic radicals having from 6 to 10 skeletal carbon atoms, mention may be made by way of example of phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.

X¹ and X² in the structural element of the general formula (Nl) have the same general, preferred and particularly preferred meanings indicated for catalysts of the general formula A.

In the general formulae (N2a) and (N2b) and analogously in the general formulae (NlOa) and (NlOb), L¹ and L² are identical or different ligands, preferably uncharged electron donors, and can have the same general, preferred and particularly preferred meanings indicated for catalysts of the general formula A. - -

Further catalysts to be covered by component (1) are catalysts of the general formulae (N2a) or (N2b) having a general structural unit (Nl) in which

M is ruthenium,

X¹ and X² are both halogen,

n is 0, 1 or 2 in the general formula (N2a) or

n' is 1 in the general formula (N2b)

L¹ and L² are identical or different and have the general or preferred meanings indicated for the general formulae (N2a) and (N2b),

_R25__R32

are identical or different and have the general or preferred meanings indicated for the general formulae (N2a) and (N2b),

m is either 0 or 1 ,

and, when m = 1 ,

A is oxygen, sulphur, C(C_rCio-alkyl)₂, -C(Ci-Ci₀-alkyl)₂-C(Ci-Ci₀-alkyl)₂-, -C(Ci_Cio-

or -N(C_rCi₀-alkyl).

M is ruthenium,

X¹ and X² are both chlorine,

n is 0, 1 or 2 in the general formula (N2a) or

n' is 1 in the general formula (N2b)

L¹ is an imidazoline or imidazolidine ligand of one of the formulae (Ilia) to (IIIu),

L² is a sulphonated phosphine, phosphate, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, sulphoxide, carboxyl, nitrosyl, pyridine radical, an imidazolidine radical of one of the formulae (Xlla) to (Xllf) or a phosphine ligand, in particular PPh₃, P(p-

Tol)₃, P(o-Tol)₃, PPh(CH₃)₂, P(CF₃)₃, P(p-FC₆H₄)₃, P(p-CF₃C₆H₄)₃, P(C₆H₄-S0₃Na)₃,

P(CH₂C₆H₄-S0₃Na)₃, P(isopropyl)₃, P(CHCH₃(CH₂CH₃))₃, P(cyclopentyl)₃,

P(cyclohexyl)₃, P(neopentyl)₃ and P(neophenyl)₃,

R²⁵-R³² have the general or preferred meanings indicated for the general formulae (N2a) and

(N2b),

m is either 0 or 1

and, when m = 1 ,

A is oxygen, sulphur, C(C_rCi₀-alkyl)₂, -C(C_rCio-alkyl)₂-C(Ci-Cio-alkyl)₂-, -C(C_rCi₀-

or -N(C_rCi₀-alkyl).

When R is bridged to another ligand of the catalyst of the formula N, this results, for example for the catalysts of the general formulae (N2a) and (N2b), in the following structures of the general formulae (N13a) and (N13b) - -

(N13a) (N13b)

where

Y¹ is oxygen, sulphur, N-R⁴¹ or P-R⁴¹, where R⁴¹ has the meanings indicated below,

R⁴⁰ and R⁴¹ are identical or different and are each alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl which may each be optionally substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl substituents,

p is 0 or 1 and

Y² when p = 1 is -(CH₂)_r- where r = 1, 2 or 3, -C(=0)-CH₂-, -C(=0)-, -N=CH-, -N(H)-

C(=0)- or, as an alternative, the entire structural unit "-Y¹ (R⁴⁰)-(Y²)_P-" is (- N(R⁴⁰)=CH-CH₂-), (-N(R⁴⁰,R⁴¹)=CH-CH₂-), and

1 2 1 25 32

where M, X¹, X V, R -R , A, m and n have the same meanings as in general formulae (N2a) and (N2b).

- -

- -

Further catalysts to be covered by component (1) are catalysts of the general formulae (Q) which can be used for hydrogenation and/or molecular weight degradation reaction of nitrile rubber during a metathesis

where

M is ruthenium or osmium,

X¹ and X² are identical or different ligands,

L is an electron donating ligand, which can be linked or not linked with X¹ to form a cyclic structure,

R¹ is hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl and

R², R³, R⁴ and R⁵ are identical or different and are each hydrogen or an organic or inorganic substituent,

R⁶ is H, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, -C(=0)R, -C(=0)OR, -

C(=0)N(R)₂, -C(=S)R, -C(=S)SR, -C(=S)OR, -C(=S)N(R)₂, -S(=0)₂N(R)₂ , - S(=0)₂R, -S(=0)R or a group containing either a C=0 or a C=S structural element adjacent to a carbon atom which is bound to Y,

n is 0 or 1 ,

wherein if n=l, then the element

Y^^( E)

n shall mean that Y and (E)_n are linked either by a single bond or by a double bond, wherein

(i) if Y and (E)_n are linked by a single bond, then

Y is oxygen (O), sulfur (S), N-R or P-R and

E is CH₂ or

(ii) if Y and (E)_n are linked by a double bond, then

Y is N or P

E is CH

wherein if n=0, then

Y is oxygen (O), sulfur (S), N-R or P-R and directly linked by a single bond to the phenyl moiety depicted above in formula (L)

and wherein in all above occurences of general formula (Q)

R is hydrogen or alkyl, cycloalkyl, alkenyl, alkynyl, aryl or heteroaryl. - -

The catalysts of the general formula (Q) are known in principle. Representatives of this class of compounds are e.g. the catalysts described by Hoveyda et al. in US 2002/0107138 Al and Angew Chem. Int. Ed. 2003, 42, 4592, and the catalysts described by Grela in WO-A-2004/035596, Eur. J. Org. Chem 2003, 963-966 and Angew. Chem. Int. Ed. 2002, 41, 4038 and also in J. Org. Chem. 2004, 69, 6894-96 and Chem. Eur. J 2004, 10, 777-784. Further representatives of this class of catalysts are the catalysts described in EP-A-1 905 777.

Further catalysts to be covered by component (1) falling under general formula (Q) have the following structures where Mes is in each case 2,4,6-trimethylphenyl

- -

- -

- -

5

- -

- -

- -

_ -

Components (2) which shall be removed by the process of the present invention comprise

iron-containing residues and degradation products thereof. Such iron-containing residues can occur due to a minimum corrosion or degradation which might happen in any metal vessel or pipes or alternatively due to the fact that iron-containing compounds might have been used as activators in the polymerisation of the nitrile rubber.

Components (III) which shall be removed according to the present invention comprise

- fatty acids, anti-oxidants and antidegradant stabilizers

ionic alkali and earth alkali based residues, in particular Ca, Na, K- based ionic residues non metallic ionic residues, in particular on the basis of phosphorus

Fatty acids, anti-oxidants and antidegradant stabilizers are used during the emulsion polymerisation of the nitrile rubbers and prevent destabililzation of the emulsion latex and resulting solid polymer.

Once the nitrile rubber is isolated and subsequently optionally hydrogenated degradation of the rubber can occur through several mechanisms including, thermal or photochemical degradation, oxidative degradation and ozone degradation. In the majority of mechanisms, degradation is initiated through the formation of a radical species. The presence of antioxidants or antidegradent stabilizers can inhibit these radicals from prematurely 'aging' the polymer. In general these antioxidants or antidegradent stabilizers can consist of hindered amines, diamines, phenylenediamines, monophenols and bisphenols which can include but are not reststricted to; butylated hydroxytoluene (BHT™, octylated diphenylamine (ODPA), Vulkanox™ 3100,

Vulkanox™ 4020, Naugard™ 446, Vulkanox™ HS (TMQ), Vulkanox™ BKF, Irganox™ MD 1024, Irganox 1010 and Vulkanox™ SKF. While it is common knowledge that these antioxidants or antidegradent stabilizers hinder premature degradation of the polymers through radical inhibiting, their benefit is in fact also a burden during the process of polymer vulcanization where the generation of radicals for the purpose of cross-linking the polymer chains is desired. For this reasoning the ability to remove the antioxidants or antidegradent stabilizers can be beneficial. - -

Purification parameters:

The process of the invention can be carried out in the presence of one or more organic solvents (other than the ionic liquid), which, for example, makes it easier to separate the (H)NBR from the ionic liquid and the catalyst present therein. Contacting the (H)NBR solution with at least one ionic liquid results in a two phase system being formed. If the components (1) to (3) to be removed have an ionic character they dissolve preferentially in the ionic liquid. Such ionic phase comprising the catalyst, the catalyst degradation products as well as all other compounds to be removed can easily be separated from the organic solvent and (H)NBR present therein. The catalyst in the ionic liquid can be recycled and used for further metathesis or hydrogenation reactions, respectively, preferably after other impurities have been removed through distillation or washing steps. Processes for recycling ionic liquids are in principle known from prior art (EP-A-1 218 890; Chem. Rev. 2002, 102, 3667-3692, US 2003/0085156 A)

Typically the solvent used is an organic solvent. Suitable organic solvents are, in particular, halogenated hydrocarbons such as dichloromethane, trichloromethane, tetrachloromethane, 1 ,2- dichloroethane or trichloroethane, aromatic compounds such as benzene, toluene, xylene, cumene or halogenobenzenes, alkanes such as pentane, hexane or cyclohexane, esters such as teri-butyl- methyl esters or acetic esters, ethers such as diethyl ether, tetrahydrofuran and dimethoxyethane, amides such as dimethylformamide, antioxidants such as hydroquinones, acetone, dimethyl carbonate or alcohols.

Preferred solvents for use in the process of the invention are C₅-C2o-alkanes, ethers and halogenated hydrocarbons. Acetone, toluene or mono-chlorobenzene are very particularly preferably used in the process of the invention.

The process pursuant to the present invention can be carried out batch-wise, i.e. discontinuously, or continuously. If the process is performed batch-wise the optionally hydrogenated nitrile rubber, in particular dissolved in an organic solvent, is contacted with at least one ionic liquid in a vessel which may be agitated. Typically the optionally hydrogenated nitrile rubber optionally dissolved is dosed into the vessel and the ionic liquid added thereafter while stirring the vessel. In an alternative embodiment the process may be performed continuously. Particularly such continuous process is performed in countercurrent flow. In another alternative embodiment it is possible to bubble the ionic liquid through the solution of the optionally hydrogenated nitrile rubber. This may be realized for both, the batch-wise as well as continuous process.

After the contacting, the ionic liquid can be removed from the optionally hydrogenated nitrile rubber e.g. by known phase separation techniques. The remaining optionally hydrogenated nitrile in the organic solvent is then coagulated using typical coagulation methods. - -

In an alternative embodiment the reaction mixture comprising the optionally hydrogenated nitrile rubber, at least one solvent and at least one ionic liquid may be fed either to an extruder or to a press and the ionic liquid as well as the solvent are removed. The remaining optionally hydrogenated nitrile rubber may be subjected to one or more further washing and drying steps.

The process of the invention is usually carried out in a temperature range from -20°C to 200°C, preferably from 0°C to 150°C, very particularly preferably from 20°C to 100°C.

- -

EXAMPLES:

The examples below describe the removal of rhodium, ruthenium, iron, fatty acid emulsifiers, metal ions, non metallic ions, and polymer stabilizers from a nitrile rubber as well as from a hydrogenated nitrile rubber. However, they shall in no way restrict the scope of the present invention.

"phr" as mentioned hereinafter means parts by weight based on hundred parts by weight of the respective rubber. The ionic liquids were purchased from Polymer Laboratories Ltd. The metathesis and hydrogenation reactions were carried out using the following nitrile rubbers:

Perbunan^® T 3429 (Nitrile Rubber) statistical butadiene-acrylonitrile copolymer with an acrylonitrile content of 34 mol% and a Mooney- Viscosity ML (l+4)@ 100 °C of 29 MU. Commercially available from LANXESS.

Perbunan^® T 4441 (Nitrile Rubber) statistical butadiene-acrylonitrile copolymer with an acrylonitrile content of 44 mol% and a Mooney- Viscosity ML (l+4)@ 100 °C of 41 MU.

The following commercially available ionic liquids were used:

1 -ethyl-3-methylimidazolium ethylsulfate

1 -ethyl-3-methylpyridinium ethylsulfate

1 -butyl-3-methylimidazolium octylsulfate

Ammoeng 102: Tetralkylammoniumsulfate having the formula

Example 1 and 2:

Analysis of Rh, Ru and Fe metal removal from a hydrogenated nitrile rubber

Perbunan^® T 4441 was metathesised utilizing 4 phr of 1-hexene and 0.007 phr Grubbs (II) generation catalyst. The low molecular weight nitrile rubber was then hydrogenated utilizing 0,02 phr of Wilkinson's catalyst (see Table 1). To the low molecular weight hydrogenated nitrile polymer solution in monochlorobenzene (100 g) was added 50 g of the ionic liquid as shown in Table 1. It was allowed to react for a determined period at a set temperature (see Table 2) while being agitated. After the set time allotment was complete, the reaction was allowed to phase separate and the ionic layer was separated from the organic solvent layer containing the rubber - - through the use of a separation funnel. The organic layer was reacted with water in order to coagulate the rubber and then isolate the rubber. The analysis of the Ru, Rh and Fe content of the rubber was then performed using ion phase chromatography and the results are shown in Table 2. Table 1:

Table 2:

As can be observed from Table 2, nearly 100% of the ruthenium (Ru) metal was removed from the polymer, 90%> and 83% respectively of the rhodium (Rh) metal was removed and 66%> and 91%> of the Fe was respectively removed.

Example 3-5:

Analysis of removal of Rh, Fe, fatty acid emulsifiers and the polymer antioxidant Vulkanox® BKF (namely 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methyl- phenol) from HNBR

The hydrogenated nitrile rubber was generated through the hydrogenation using 0,05 phr Wilkinson's catalyst and 1 phr triphenylphosphine of a 15 wt.-%> Perbunan^® T 3429 solution in monochlorobenzene at 138°C and 85 bar of H₂ pressure. Completion of the hydrogenation was monitored through the achievement of 99+%> hydrogenation of the carbon-carbon double bonds.

To a 25g solution of said hydrogenated nitrile rubber was added 25g of an ionic liquid as shown in Table 3. The mixture was agitated for a set time and temperature (see Table 3), the mixture was then allowed to cool and phase separate into the ionic liquid layer and the organic solvent layer.

The analysis of the Rh and Fe content of the hydrogenated nitrile rubber was then performed using - - ion phase chromatography. The analysis of the fatty acid and the antioxidant content and residues in the polymer was performed via gas chromatography. All results are shown in Table 4.

Table 3:

Table 4:

The control data have been obtained using a hydrogenated nitrile rubber (Therban A 3406, abvailable from Lanxess Deutschland GmbH) which is manufactured on a commercial scale by hydrogenation of Perbunan^® T 3429 also using Wilkinson's catalyst and triphenylphosphine in principally the same manner as described above for Examples 3 to 5.

Table 4 illustrates that increasing the temperature at which the reaction proceeds may improve the efficiency of the purification. As the temperature is increased from 22°C to 100°C and on to 140°C the efficiency of the rhodium (Rh) removal rises from 83% to 90%> respectively. The temperature effect relating to the efficiency of the iron (Fe) removal is lesser with only an increase in efficiency from 97%) to 99+%> occurring when moving from 22°C to 100°C respectively. Neither the antioxidant (Vulkanox^® BKF) nor the fatty acid emulsifier content were observed to be dependent on temperature as 91%> of the fatty acid emulsifier was removed from each example, while 87% to 90% of the BKF was removed.

Example 6-9: - -

Analysis of Na, K, Mg and Ca removal from a nitrile rubber solution.

To a 75 g solution of Perbunan^® T 3429 in monochlorobenzene was added a set quantity of an ionic liquid as identified in Table 5 and the mixture was agitated for a set time and temperature (see Table 5). After the set time allotment was complete, the reaction was allowed to phase separate and the ionic layer was separated from the organic solvent layer containing the nitrile rubber through the use of a separation funnel. The organic layer was then contacted with water in order to coagulate the nitrile rubber. Thereafter the rubber was isolated. The analysis of the metal ion content of the nitrile rubber was followed by ion phase chromatography (see Table 6).

Table 5

Table 6

* Perbunan^® T 3429

Table 6 illustrates that the purification of the nitrile rubber with ionic liquids afforded a decrease in the sodium (Na) content of more than 45% for Examples 8 and 9, a decrease in potassium (K) content of more than 70% for examples 6 and 7, a decrease in the calcium (Ca) content of more than 50% and a decrease in magnesium (Mg) ion content of more than 15%. - -

Example 10-11:

Analysis of Na, K and antioxidant removal from a nitrile rubber

To a lOOg solution of Perbunan^® T 3429 in monochlorobenzene was added a set quantity of an ionic liquid as defined in Table 7 and the mixture was then agitated for a set time and temperature as shown in Table 7, too. After the set time allotment was complete, the reaction was allowed to phase separate and the ionic layer was separated from the organic solvent layer containing the nitrile rubber through the use of a separation funnel. The organic layer was reacted with water in order to coagulate the nitrile rubber and the rubber was isolated from the mixture thereafter.

Analysis of the resulting polymer is outlined in Table 8.

Table 7

Table 8

* Perbunan^® T 3429

As can be seen from Table 8, the purification with the ionic liquids afforded a decrease in the antioxidant content of the polymer of more than 50%, a decrease in the sodium (Na) content of more than 40%> and a decrease in potassium (K) ion content of more than 45%.

Claims

CLAIMS:

1. A process for purifying an optionally hydrogenated nitrile rubber comprising contacting such optionally hydrogenated nitrile rubber with at least one ionic liquid.

2. The process according to claim 1 wherein the ionic liquid represents a compound on the basis of quaternary ammonium cations, quaternary phosphonium cations, optionally substituted pyridinium cations, optionally substituted imidazolium cations, optionally substituted pyrazolium cations, and optionally substituted pyrimidinium cations.

3. The process according to claim 1 wherein the ionic liquid is selected from the group consisting of the ionic liquids having the general formulae (1) to (5)

(5)

wherein

A^n" shall mean an anion selected from the group consisting of hexafluorophosphate (PF₆ ^~), nitrate (NO₃)^", halides, preferably fluoride, chloride, bromide or iodide, sulfates, sulfonates, aluminates, carboxylates, phosphates and borates, with n meaning 1 , 2 or 3 depending on the negative charge of the aforementioned anions and (1/n) therefore representing 1 for a one time negatively charged anion, 1/2 for a two times negatively charged anion and 1/3 for a three times negatively charged anion, X is nitrogen or phosphorous,

Pv¹, R², R³, R⁴, R⁵ and R⁶ are identical or different and represent hydrogen, halide, alkoxy, alkyl, substituted alkyl, aryl, preferably phenyl, substituted aryl, and

4. The process according to claim 1 wherein the ionic liquid is selected from the group consisting of the ionic liquids having the general formulae (l)-(5) wherein

(l/n) A^n- represents PF₆\ N0₃ ^", F\ CI^", Br , Γ, R⁷S0₃ ^", R⁷OS0₃ ^", R⁷C0₃ ^", BF₄ ^", and

B(R⁷)₄ ^~, where R⁷ is identical or different and represents alkyl, substituted alkyl, aryl, more preferably phenyl, substituted aryl, or alkoxy.

5. The process according to claim 1 wherein the ionic liquid is selected from the group consisting of l-ethyl-3-methyl-pyridinium ethylsulfate, l-ethyl-3-methyl-imidazolium ethylsulfate, l-methyl-3-butylimidazolium chloride, l-methyl-3-ethylimidazolium chloride, N-butylpyridinium chloride, tetrabutylphosphonium chloride, ammonium hexa- fluorophosphate, ammonium tetrafluoroborate, ammonium tosylate, ammonium hydrogen sulphate, pyridinium hexafluorophosphate, l-methyl-3 -butyl imidazolium hexafluoro- phosphate, pyridinium tetrafluoroborate, pyridinium hydrogen sulphate, N-butylpyridinium hexafluorophosphate and combinations of two or more of the aforementioned ionic liquids.

6. The process according to claim 1, wherein the nitrile rubber contacted with the ionic liquid represents a copolymer containing repeating units of at least one α,β-unsaturated nitrile and at least one conjugated diene.

7. The process according to claim 6, wherein the nitrile rubber contacted with the ionic liquid contains repeating units of at least one conjugated diene selected from the group consisting of 1 ,2-butadiene, 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and mixtures thereof, preferably 1,3-butadiene, and of at least one α,β-unsaturated nitrile selected from the group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile and mixtures thereof, preferably acrylonitrile.

8. The process according to claim 6 or 7, wherein the nitrile rubber additionally contains repeating units of at least one further copolymerizable termonomer, preferably selected from the group consisting of α,β-unsaturated monocarboxylic acids, their esters, their amides, α,β-unsaturated dicarboxylic acids, their monoesters or diesters, or their corresponding anhydrides or amides.

9. The process according to claim 1, wherein the nitrile rubbers have Mooney viscosities (ML (1+4 @100°C)) of from 10 to 150, preferably from 20 to 100, Mooney units determined at 100°C in accordance with DIN 53523/3 or ASTM D 1646.

The process according to claim 1, wherein the nitrile rubber is prepared by an emulsion- polymerisation.

The process according to claim 10, wherein the polymerisation is followed by a metathesis reaction and/or hydrogenation reaction before the resulting nitrile rubber or partially or fully hydrogenated nitrile rubber is contacted with the at least one ionic liquid.

The process according to claim 11, wherein the component types (1) to (3) can be removed from the nitrile rubber which can also be partially or fully hydrogenated

(2) iron containing residues and degradation products thereof, and

The process according to claim 12, wherein the optionally hydrogenated nitrile rubber is first dissolved in one or more organic solvent(s) other than the ionic liquid and then this solution is contacted with the at least one ionic liquid this resulting in a two phase system wherein the components (1) to (3) being preferentially getting dissolved in the ionic liquid and wherein the ionic liquid is separated from the organic solvent the latter containing the optionally hydrogenated nitrile rubber.

The process according to claim 13, wherein the organic solvent is selected from the group consisting of halogenated hydrocarbons, preferably dichloromethane, trichloromethane, tetrachloromethane, 1 ,2-dichloroethane and trichloroethane, aromatic compounds, preferably benzene, toluene, xylene, cumene and halogenobenzenes, alkanes, preferably pentane, hexane and cyclohexane, esters, preferably tert-butylmethyl esters and acetic esters, ethers, preferably diethyl ether, tetrahydrofuran and dimethoxyethane, amides, preferably dimethylformamide, and antioxidants, preferably hydroquinones, acetone, and dimethyl carbonate, and alcohols.

15. The process according to claim 1 which is carried out batch-wise or continuously.