Title of Invention

A PROCESS FOR PREPARING MIXTURES OF MONOOLEFINIC C5 MONONITRILES

Abstract

A process for preparing mixtures of monoolefinic C5 mononitriles with nonconjugated C=C and C=N bonds by catalytic hydrocyanation of 1,3-butadiene or a 1,3-butadiene-containing hydrocarbon mixture, wherein the hydrocyanation takes place in the presence of a catalyst which comprises at least one metallocene-phosphorus(lll)-nickel{0) complex which comprises at least one monodentate or bidentate metallocene-phosphorus(III) ligand of the formula I

Full Text

The present invention relates to a process for preparing mixtures if monoolefinic C5 mononitriles with nonconjugated C=C and C=N londs by catalytic hydrocyanation of a 1,3-butadiene-containing lydrocarbon mixture. ?here is a great demand throughout the world for [,a)-alkylenediamines which are important starting materials in ;he industrial preparation of polyamides (nylons). The [fCO-alkylenediamines such as hexamethylenediamine are obtained ilmost exclusively by hydrogenation of the corresponding linitriles. Virtually all industrial routes for preparing lexamethylenediamine are therefore essentially variants of the ireparation of adiponitrile, about 1.0 million tons of which are iroduced around the world each year. 'our routes, which differ in principle, for preparing idiponitrile are described in K. Weissermel, H.-J. Arpe, industrielle Organische Chemie, 4th edition, VCH Weinheim, pages 166 et seq.: dehydrating amination of adipic acid with eimmonia in the liquid or gas phase with intermediate formation of the diamide; 1. indirect hydrocyanation of 1,3-butadiene via intermediate 1,4-dichlorobutenes; I. hydrodimerization of acrylonitrile in an electrochemical process, and 1. direct hydrocyanation of 1,3-butadiene with hydrogen cyanide. :n the last-mentioned process, monoaddition in a first stage results in a mixture of isomeric pentenonitriles, which is -somerized in a second stage mainly to 3- and 4-pentenonitriles. :n a subsequent third stage, anti-Markownikoff addition of lydrogen cyanide onto 4-pentenonitrile results in adiponitrile. This reaction takes place in the liquid phase in a solvent such as tetrahydrofuran at a temperature in the range 30 - 150°C under atmospheric pressure. The catalysts used for this are nickel complexes with phosphine or phosphite ligands and metal salt promoters. Complex phosphine ligands bound to metallocenes for stabilizing the nickel are not described in the abovementioned review. There is a general description of the addition, with heterogeneous and homogeneous catalysis, of hydrogen cyanide onto olefins in Applied Homogeneous Catalysis with Organometalic Compounds, Vol. 1, VCH Weinheim, pages 465 et seq.. The catalysts used for this are, in particular, based on phosphine and phosphite complexes, not bound to metallocenes, of nickel and palladium, which make high product selectivity, improved conversions and reduced reaction times possible. Adiponitriie is prepared by hydrocyanation of butadiene mainly using nickel(O) phosphite catalysts, in the presence or absence of a Lewis acid as promoter- The reaction can generally be divided into three steps: 1. synthesis of mononitriles by hydrocyanation of 1,3-butadiene; 2. isomerization; 3. synthesis of dinitriles. Formation of the monoadduct results in an isomer mixture composed of 3-pentenonitrile and 2-methyl-3-butenonitrile, and the selectivity for the linear 3-pentenonitrile is about 70% or less, depending on the catalyst used. If this first reaction step is carried out in the absence of Lewis acids, generally there is no second addition of hydrogen cyanide and the resulting product mixture can be subjected to an isomerization using the same ::atalyst systems as in the first reaction step, but this time in the presence or absence of a Lewis acid such as ZnCl2 as promoter. In this there is, on the one hand, isomerization of 2-methyl-3-butenonitrile to 3-pentenonitrile and, on the other :iand, isomerization of 3-pentenonitrile to the various i-pentenonitriles. This publication mentions that the most :hermodynaraically stable isomer, 2-pentenonitrile in which the :,N triple bond is conjugated with the C,C double bond, inhibits ihe reaction because it acts as catalyst poison. The required Isomerization to 4-pentenonitrile is made possible only because J-pentenonitrile is isomerized considerably faster to 1-pentenonitrile than to 2-pentenonitrile. The usual catalysts for the hydrocyanation of 1,3-butadiene are, i.n particular, the abovementioned nickel(O) phosphite catalysts jith phosphite ligands without complex modification.. EP-A-0 274 401 describes a process for the hydrocyanaticn of pure butadiene using a nickel catalyst having a mixture of phenyl and m,p-tolyl phosphite ligands. C.A. Tolman et al. describe, in Organometallics 3 (1984) 33 et seq., a catalytic hydrocyanaticn of olefins by nickel(O) phosphite complexes specifically taking account of the effects of Lewis acids on the addition of hydrogen cyanide. In Advances in Catalysis, Volume 33, 1985, Academic Press, Inc., page 1 et seq. there is a review-like description of the homogeneous nickel-catalyzed hydrocyanaticn of olefins. This deals in particular with mechanistic aspects of the monohydrocyanation of butadiene to isomeric pentenonitriles, of the isomerization of 2-methyl-3-butenonitrile to 3-pentenonitrile and of the second addition of hydrogen cyanide to prepare adiponitrile. The catalysts employed are nickel (0) complexes, preferably with phosphite ligands. Jsual phosphines such as triphenylphosphine or l.,2-bis{diphenylphosphino)et.hane have only low catalytic activity, if any, in the hydrocyanaticn of olefins. ro 95/30680 describes bidentate phosphine chelate ligands in jhich the phosphine groups are bonded to aryl radicals which are :used by two bridges in ortho positions. In these, the first jridge comprises an 0 or S atom and the second bridge comprises in O, S or substituted N, Si or C atom. The two phosphine ligands ire each located on a different aryl radical in the position irtho to the first bridge. These bidentate phosphine ligands are suitable, in the form of their transition metal complexes, as catalysts for hydroformylation, hydrogenation, polymerization, .somerization, carboxylation, crosscoupling, metathesis and lydrocyanation. r. Chem. Soc, Chem. Commun. (1995) 2177 et seq. describes the iffect of the bonding angle of the abovementioned bidentate ihosphine ligands on the activity and selectivity in the lickel-catalyzed hydrocyanaticn of styrene. lone of the abovementioned publications describes a process for atalytic hydrocyanaticn using monodentate or polydentate iickel(0)-phosphorus(III) complexes in which the phosphorus(III) igands in turn are covalently bonded to one or both of the cyclopentadienyl ligands of a metallocene. EP-A 564 406 and EP-A 612 75/ describe ferrocenyldiphosphines as ligands for homogeneous catalysts and the use of these catalysts for enantioselective hydrogenation. In these ligands, two phosphine groups are bonded in the ortho position to the same cyclopentadienyl ligand of the ferrocene, one of them directly to the C5 ring and the other via a substituted Ci-alkylene group. The rhodium and iridium complexes with these ligands are suitable as homogeneous enantioselective catalysts for hydrogenation of prochiral compounds with carbon or carbon/heteroatom double bonds. The use of these catalysts for hydrocyanation is not described. Catalysts for asymmetric addition of hydrogen cyanide onto alkenes based on transition metal(O) complexes have been disclosed. Thus, Aust. J. Chem. 35 (1982) 2041 et seq. describes the use of [(+)-{diop)]2Pd and ((+)-(diop)]2Ni {(+)-(diop) = (+)-{2S,3S)-(2,3-isopropylidenedioxy-l,4-butanediyl)bis{diphenyl-phosphine)} as catalysts in enantioselective hydrocyanation. J. Am. Chem. Soc. 118 (1996) 6325 et seq. describes the relationship of the electronic asymmetry of the ligands to the observed enantioselectivity in asymmetric hydrocyanation using electronically nonsymmetrical bis-3,4-diarylphosphonite ligands based on a-D-fructofuranosides. It is an object of the present invention to provide a process for hydrocyanation in which the catalysts employed are to show high selectivity and good catalytic activity especially in the hydrocyanation of 1,3-butadiene-containing hydrocarbon mixtures to prepare mixtures of monoolefinic Cs-mononitriles with nonconjugated C=C and C=N bonds and in the first and second addition of hydrogen cyanide to prepare adiponitrile. we have found that this object is achieved by employing catalysts which comprise at least one metallocene-phosphorus(III}-nickel(0} complex. The present invention thus relates to a process for preparing mixtures of monoolefinic C5 mononitriles with nonconjugated C=C and CsN bonds by catalytic hydrocyanation of 1,3-butadiene or a ,,^. . . ' ^ ^ undjer known hydrocYanatlon conditions 1,3'butadiene-containing hydrocarbon mixture* wnerein the hydrocyanation takes place in the presence of a catalyst which comprises at least one metallocene-phosphorus{III)-nickel(0) complex which comprises at least one monodentate or bidentate metallocene-phosphorus(III) ligand of the formula I 1-ethylpropyl, n-hexyl, 2-hexyl, 2-niethylpentyl, 3-inethylpentyl, 4-methylpentyl, 1, 2-dimethylbutyl, 1,3-dirnethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3 , 3-diinethylbutyl, 1,1, 2-triinethylpropyX, 1,2,2-triinethylpropyl, 1-ethylbutyl, 2-ethylbutyl, l-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl, 2-ethylpentyl, 1-propylbutyl and octyl. The cycloalkyl group is preferably a Cs-Cy-cycloalkyl group such as cyclopentyl, cyclohexyl or cycloheptyl. If the cycloalkyl group is substituted, it preferably has 1, 2, 3, 4 or 5, in particular 1, 2 or 3, alkyl radicals as substituents. Aryl is preferably phenyl, tolyl, xylyl, mesityl or naphthyl and, in particular, phenyl. Substituted aryl radicals have as substituents for example Ci-Cg-alkyl, Ci-Cg-alkoxy, halogen, trifluoromethyl, nitro or carbcxyl. As a rule, 1, 2 or 3 substituents are preferred. The L radicals in the PL2 groups are different or, preferably, identical. Examples of suitable L radicals are Ci-Ci2-alkyl and C5-Ci2-cycloalkyl, each of which can be substituted by one, two or three of the following groups: Ci-C4-alkyl, Ci-C4-alkoxy. Further examples of suitable L radicals are aryl which can be substituted by one, two or three of the following groups: Ci-C^-alkyl, Ci-C4-alkoxy, halogen, trifluoromethyl, sulfo, alkylsulfonyl, carboxyl, alkanoyloxy, alkoxycarbonyl, hydroxyl, nitro or cyano. The L radicals are preferably phenyl. If one of the radicals R^, R^', R^, R^', R^, R^', R^ or R^' is alkyl interrupted by an oxygen atom in ether linkage, possible examples thereof are 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 3-butoxypropyl, 2- or 4-niethoxybutyl, 2-or 4-ethoxybutyl, 2- or 4-butoxybutyl and, preferably, 2-methoxyethyl. If one of the radicals R^, R^', R^, R3', Ri, Ri', R5 or R^' is alkyl substituted by a radical of the formula NE^E^, possible examples are N,K-dimethylaminomethyl, N,N-dimethylaminoethyl, N,N-diethylaminoi[iethyl, N,N-diethylaminoethyl or N,N-dimethylaminopropy1. If in each case two of the substituents R^, R3, R4, R5 and/or R^', R3', R4', R5' in adjacent positions are, together with the part of the cyclopentadienyl ring connecting them, an aromatic or nonaromatic, 5- to 7-membered carbocyclic or heterocyclic system which additionally has 1, 2 or 3 heteroatoms selected from 0, N ( and S, possible examples are indenyl, fluorenyl, azulenyl etc. The two cyclopentadienyl rings in the metallocene-phosphorus(III) ligand of the formula I may be in the eclipsed or staggered conformation with various conformational angles. The planes of the cyclopentadienyl rings may be parallel or inclined toward one another, eg. depending on the central metal. The catalysts employed according to the invention comprise metallocene-phosphorus(III)-nickel(0) complexes having a) metallocene-phosphorus(III) ligands of the formula I having only one radical of the formula PL2, b) bidentate metallocene-phosphorus(III) ligands of the formula I having two radicals of the formula PL2 where the abovementioned structural circumstances of the ligand of the formula I make two-fold coordination of a transition metal possible, and c) bidentate or polydentate metallocene-phosphorus(III) ligands of the formula I, in which case one ligand coordinates different transition metals by different radicals of the formula PL2, it being possible for chain-like metallocene-phosphorus(lll)-nickel{0) complexes to result, eg. in a sandwich structure. A zero valency transition metal may moreover coordinate one, two, three or four ligands of the formula I and, where appropriate, further ligands which are described hereinafter. The central metal of the metallocene-phosphorus(III) ligand is preferably Fe. In a suitable embodiment of the process according to the invention, the catalysts employed are those where Rl is a radical of the formula PL2 where the L radicals are phenyl. ] Ri' is hydrogen or a radical of the formula PL2 where the L radicals are, independently of one another, alkyl, cycloalkyl, substituted aryl and, in particular, phenyl, one of the substituents R^, R2', R3, R3'^ R4^ R4'^ R5 or R^', I preferably that in the position a to R^ or R^', is hydrogen or alkyl which may be interrupted by an oxygen atom or substituted by a radical of the formula NE^E^ where E^ and E^ can be identical or different and are alkyl, and the other substituents R2, R2', R3, R3', R4, R4'^ R5 ^ R5 ' ^re, independently of one . another, hydrogen or methyl. R^'is then preferably hydrogen or a radical of the formula PL; where the L radicals are isopropyl, cyclohexyl, trifluoromethyl-substituted phenyl or phenyl. ) The catalysts according to the invention may, in addition to the metallocene-phosphine ligands of the formula I described above, additionally have at least one other ligand which is selected , from halides, amines, carboxylates, acetylacetonate, aryl- or ' alkylsulfonates, hydride, CO, olefins, dienes, cycloolefins, nitriles, H-containing heterocycles, aromatic and heteroaromatic systems, ethers, PF3 and monodentate, bidentate and polydentate phosphine, phosphinite, phosphonite and phosphite ligands, which is likewise monodentate, bidentate or polydentate and coordinates ' to the zero valency transition metal. In a suitable embodiment of the process according to the invention, the catalysts employed comprise as metallocene-phosphorus(III) ligand 1,1'-bis(diphenylphosphino)ferrocene, 1,1'-bis(dicyclohexylphosphino)ferrocene, or 1,1'-bis(diisopropylphosphino)ferrocene. In a possible embodiment, the catalyst employed according to the invention comprises a chiral metallocene-phosphine ligand of the formula I so that it is suitable for enantioselective catalysis. Enantioselective catalysis generally entails a compound which is already chiral or prochiral being reacted with use of the I catalyst according to the invention, resulting in products with an enantiomeric excess or, preferably, enantiomerically pure products. The catalysts according to the invention can be prepared by reacting at least one metallocene-phosphine ligand of the formula I and nickel powder or a nickel compound or a nickel complex in an inert solvent. Suitable nickel compounds in this connection are, for example, compounds in which the transition metal has an oxidation state higher than 0 and which are reduced in situ in the reaction with the inetallocene-phosphorus{III) ligand of the formula I, in the presence or absence of a suitable reducing agent. These include, for example, the halides, preferably the chlorides, the acetates and the acetylacetonates of the abovementioned transition metals. Nickel{0) complexes are preferably prepared using NiClj, Examples of suitable reducing agents are alkali metals such as Na and K, and aluminum, and trialkylaluminum compounds. If complex compounds of the transition metal are employed to prepare the metallocene-phosphorus(lll)-nickel(0) complexes, the transition metal preferably has zero valency therein. Complexes with ligands which correspond to the abovementioned additional ligands in the complexes according to the invention are preferably employed for the preparation. In this case, preparation takes place by partial or complete ligand exchange with the metallocene-phosphorus(IIIl ligands of the formula I described above. In a suitable embodiment of the process according to the invention, the nickel complex is bis{1,5-cyclo-octadiene)nickel(0). Suitable inert solvents for preparing the metallocene-phosphorus(lll)-nickel(0) complexes are, for example, aromatic compounds such as benzene, toluene, ethylbenzene, chlorobenzene, ethers, preferably diethyl ether and tetrahydrofuran, or haloalkanes, for example dichloromethane, chloroform, dichloroethane and trichloroethane. The temperature in this case is in the range from -70oc to 150oc, preferably from 0°C to 100°C, particularly preferably at about room temperature. Mixtures of monoolefinic C5 mononitriles with nonconjugated C=C and CsN bonds can be prepared by reacting a 1,3-butadiene-containing hydrocarbon mixture in the presence of one of the catalysts described above. This preferably results in mixtures with a high content of linear pentenonitriles. Mixtures of monoolefinic C5 mononitriles which contain, for example, 3-pentenonitrile and 2-inethyl-3-butenonitrile, and which are suitable as intermediates for further processing to adiponitrile, can be prepared by employing pure butadiene or 1,3-butadiene-containing hydrocarbon mixtures. If a hydrocarbon mixture is employed to prepare monoolefinic C5 mononitriles by the process according to the invention, it preferably has a 1,3-butadiene content of at least 10% by volume, preferably at least 25% by volume, in particular at least 40% by i^olume. 1,3-Butadiene-containing hydrocarbon mixtures are obtainable on the industrial scale. Thus, for example, in petroleum processing the steam cracking of naphtha results in a hydrocarbon mixture tfhich is called the C4 cut and has a high total olefin content, about 40% comprising 1,3-butadiene and the remainder monoolefins and polyunsaturated hydrocarbons, plus alkanes. These streams always also contain small amounts, in general up to 5%, of ilkynes, 1,2-dienes and vinylacetylene. ?ure 1,3-butadiene can be isolated, for excimple, by extractive iistillation from industrial hydrocarbon mixtures. li cuts are, where appropriate, essentially freed of alkynes, such is propyne or butyne, of 1,2-dienes such as propadiene, and of ilkenynes such as vinylacetylene. Otherwise, in some :ircumstances the resulting products have a C=C double bond in ;onjugation with the C = N bond. It is disclosed in Applied Jomogeneous Catalysis with Organometalic Compounds, Vol. 1, VCH Jeinheim, page 479, that the conjugated 2-pentenonitrile which results from the isomerization of 2-methyl-3-butenonitrile and !-pentenonitrile acts as inhibitor of the second addition of lydrogen cyanide to give adiponitrile. It has been found that the ibovementioned conjugated nitriles obtained on hydrocyanation of I C4 cut which has not been pretreated also act as catalyst )oisons for the first reaction step in the preparation of adipic icid, the monoaddition of hydrogen cyanide. 'his is why the components which constitute catalyst poisons in :atalytic hydrocyanation, especially alkynes, 1,2-dienes and mixtures thereof, are partly or completely removed where appropriate from the hydrocarbon mixture. To remove these components, the C4 cut is subjected, for the addition of hydrogen cyanide, to a partial catalytic hydrogenation. This partial hydrogenation takes place in the presence of a hydrogenation catalyst which is able to hydrogenate alkynes and 1,2-dienes selectively in the presence of other dienes and monoolefins. Suitable heterogeneous catalyst systems for the selective hydrogenation generally comprise a transition metal compound, eg. on an inert carrier. Suitable inorganic carriers are the oxides usual for this purpose, especially silicas and aluminas, aluminosilicates, zeolites, carbides, nitrides etc. and mixtures thereof, preferably used as carriers are AI2O3, Si02 and mixtures thereof. The heterogeneous catalysts used are particularly those described in US-A-4,587,369; US-A-4,704,492 and US-A-4,493,906 which are incorporated herein by reference. Further suitable Cu-based catalyst systems are marketed by Dow Chemical as KLP catalyst. Addition of hydrogen cyanide onto 1,3-butadiene or a 1,3-butadiene-containing hydrocarbon mixture, eg. a pretreated, partially hydrogenated C4 cut, can take place continuously, semicontinuously or batchwise. In a suitable variant of the process according to the invention, the addition of hydrogen cyanide takes place continuously. Reactors suitable for the continuous reaction are known to the skilled worker and are described, for example, in Ullmanns Enzyklopadie der technischen Chemie, vol. 1, 3rd Edition, 1951, page 743 et seq.. A cascade of stirred vessels or a tubular reactor is preferably used for the continuous variant of the process according to the invention. In a preferred variant of the process according to the invention, the addition of hydrogen cyanide onto 1,3-butadiene or a 1,3-butadiene-containing hydrocarbon mixture takes place semicontinuously. The semicontinuous process comprises: a) charging a reactor with the hydrocarbon mixture, with or without part of the hydrogen cyanide and a hydrocyanation catalyst according to the invention which has been generated in situ where appropriate, with or without a solvent, b) reacting the mixture at elevated temperature under elevated pressure, with hydrogen cyanide being fed in at the rate of its consumption in the semicontinuous procedure, ::) completing the conversion by subsequent reaction, followed by workup. Suitable pressure-resistant reactors are known to the skilled i/orker and are described, for example, in Ullmanns Enzyklopadie ier technischen Chemie, Vol. 1, 3rd Edition, 1951, page 769 et jeq.. An autoclave is generally used for the process according to :he invention and can, if desired, be equipped with a stirring levice and an inner lining. Account should preferably be taken of :he following for the above steps: )tep a)! iefore starting the reaction, the pressure-resistant reactor is :harged with the partially hydrogenated C4 cut, hydrogen cyanide, L hydrocyanation catalyst and, where appropriate, a solvent, luitable solvents are those mentioned above for the preparation )f the catalysts according to the invention, preferably aromatic lydrocarbons such as toluene, xylene or tetrahydrofuran. itep b): 'he mixture is generally reacted at elevated temperature under ilevated pressure. The temperature is generally in the range from .bout 0 to 200°C, preferably about 50 to ISCC. The pressure is enerally in the range from about 1 to 200 bar, preferably about to 100 bar, in particular 1 to 50 bar, particularly preferably to 20 bar. Hydrogen cyanide is fed in during the reaction at he rate at which it is consumed, keeping the pressure in the utoclave essentially constant. The reaction time is about 0 minutes to about 5 hours. tep c): o complete the conversion the reaction time can be followed by a eriod of from 0 minutes to about 5 hours, preferably about hour to 3.5 hours, for subsequent reaction without hydrogen yanide being fed into the autoclave. The temperature during this eriod is kept essentially constant at the reaction temperature reviously set. workup takes place by conventional processes and omprises removal of the unreacted 1,3-butadiene and unreacted ydrogen cyanide, eg. by washing or extraction, and distillation _f the remaining reaction mixture to remove the required products and recover the still active catalyst. In another suitable variant of the process according to the invention, the addition of hydrogen cyanide onto the 1,3-butadiene-containing hydrocarbon mixture takes place batchwise. The reaction conditions for this are essentially those described for the semicontinuous process but without additional hydrogen cyanide being fed in, but being completely present from the outset, in step b). The preparation of adiponitrile from a butadiene-containing mixture by addition of 2 mole equivalents of hydrogen cyanide can generally be divided into three steps: 1. Preparation of C5 monoolefin mixtures with nitrile functionality. 2. Isomerization of the 2-methyl-3-butenonitriIe present in the mixtures to 3-pentenonitrile and isomerization of 3-pentenonitrile thus formed and present in the mixtures from step 1 to various n-pentenonitriles. This is intended to form a maximum content of 3-pentenonitrile and a minimum content of conjugated 2-pentenonitrile and 2-methyi-2-butenonitrile, which act as catalyst poison. 3. Preparation of adiponitrile by addition of hydrogen cyanide onto the 3-pentenonitrile which was formed in step 2 and which is previously isomerized in situ to 4-pentenonitrile. By-products of this are, for example, 2-inethylglutaronitrile from Markownikoff addition of hydrogen cyanide onto 4-pentenonitrile or anti-Markownikoff addition of hydrogen cyanide onto 3-pentenonitrile, and ethylsuccinonitrile from Markownikoff addition of hydrogen cyanide onto 3-pentenonitrile. The catalysts based on metallocene-phosphorus(lll) ligands and employed according to the invention are also suitable and advantageous for the positional and double-bond isomerization in step 2 and the second addition of hydrogen cyanide in step 3. In a preferred embodiment of the process according to the invention, the ratio of the amounts of 3-pentenonitrile to 2-methyl-3-butenonitrile obtained in the monoaddition of hydrogen cyanide onto the 1,3-butadiene-containing hydrocarbon mixture is at least 5:1, preferably at least 10:1, in particular at least 20:1. It is therefore generally possible to dispense with division of the process for preparing adiponitrile into the three steps of monoaddition of hydrogen cyanide onto a 1,3-biJtadiene-containing hydrocarbon mixture; isomerization; '-addition of hydrogen cyanide onto 4-pentenonitrile formed in situ; and the addition of 2 mole equivalents of hydrogen cyanide onto a 1,3-butadiene-containing hydrocarbon mixture can be > designed as a one-stage process. The present invention therefore also relates to a process for preparing adiponitrile whicn comprises I) catalytic hydrocyanation of a mixture, which has been prepared as previously described, of C5 mononitriles, where appropriate after further workup or isomerization, or II) catalytic hydrocyanation of a 1,3-butadiene-containing hydrocarbon mixture in a one-stage process, without workup and isomerization of C5 mononitriles, in the presence of a catalyst of the formula I. Not only do the catalysts employed according to the invention , advantageously show high selectivity with regard to the monoaddition products obtained on hydrocyanation of 1,3-butadiene-containing hydrocarbon mixtures, but they can also be mixed with an excess of hydrogen cyanide for the hydrocyanation with negligible deposition of inactive nickel(II) compounds such as nickel(II) cyanide. In contrast to known hydrocyanation catalysts based on noncomplex phosphine and phosphite ligands, the catalysts of the formula I are thus suitable not only for continuous hydrocyanation processes in which an excess of hydrogen cyanide in the reaction mixture can generally be effectively avoided, but also for semicontinuous processes and batch processes in which, in general, a large excess of hydrogen cyanide is present. The catalysts employed according to the invention, and the hydrocyanation processes based thereon, thus generally display higher catalyst recycling rates and longer catalyst service lives than known processes. This not only improves the economics but is also ecologically advantageous because the nickel cyanide formed from the active catalyst with hydrogen cyanide is highly toxic and must be worked up or disposed of at high cost. Besides hydrocyanation of 1,3-butadiene-containing hydrocarbon mixtures, the catalysts of the formula I are generally suitable for all conventional hydrocyanation processes. Those which may be particularly mentioned are the hydrocyanation of styrene and of f3 3-pentenonitrile. The catalysts described above can also be employed for isomerizing 2-methyl-3-butenonitrile to 3-pentenonitrile. Catalysts which comprise chiral metallocene-phosphorus{III) ligands of the formula I are suitable for enantioselective hydrocyanation. The invention is illustrated in detail by the following, non-limiting examples. Examples Example 1 (according to the invention): Hydrocyanation of 1,3-butadiene 0.82 g of bis(l,5~cyclooctadiene)nickel(0}, 3.32 g of 1,1'-bis(diphenylphosphino)ferrocene and 10 ml of toluene are mixed together in a glass autoclave at room temperature under argon, the reaction mixture immediately becoming reddish brown. After about 1 hour, a mixture of 16.2 g of 1,3-butadiene and 40 g of toluene is added. The glass autoclave is tightly closed and the mixture is heated to 90°C, an initial pressure of 3.4 bar being set up. The temperature is kept constant at 90oc, and a mixture of 4.0 g of freshly distilled hydrocyanic acid and 30 ml of toluene is metered in continuously, over a period of 80 minutes. The pressure has fallen to 1.4 bar after this. The reaction is then completed by subsequent reaction at 90°C for 110 minutes. Toluene is used to rinse out the reactor. The progress of the reaction is followed by measuring the pressure and temperature. In a subsequent Volhard cyanide determination, no cyanide is detected, and thus there has been virtually complete conversion of hydrogen cyanide. JC analysis (column: 30 m stable wax, temperature program: 5 minutes isothermal at 50°C, subsequent heating to 240°C at 5°C/min, gas chromatograph: Hewlett Packard HP-5890) with internal standard (benzonitrile): 75% of 3-pentenonitrile and 2-methyl-3-butenonitrile based on hydrogen cyanide. 3-Pentenonitrile : 2-methyl-3-butenonitrile ratio = 30:1. Example 2 (according to the invention): Hydrocyanation of 1,3-butadiene 0.14 g of bis(l,5-cyclooctadiene)nickel(0}, 1.65 g of 1,1'-bis(diphenylphosphino)ferrocene and 10 ml of toluene are mixed together in a glass autoclave at room temperature under argon, the reaction mixture immediately becoming reddish brown. After about 1 hour, a mixture of 16.2 g of 1,3-butadiene and 40 g of toluene is added. The glass autoclave is tightly closed and the mixture is heated to 80°C, an initial pressure of 3.4 bar being set up. The temperature is kept constant at 80^C, and a mixture of 4.0 g of freshly distilled hydrocyanic acid and 30 ml of toluene is metered in continuously, over a period of 90 minutes. The pressure has fallen to 2.0 bar after this. The reaction is then completed by subsequent reaction at 80°C for 60 minutes. Toluene is used to rinse out the reactor. The progress of the reaction is followed by measuring the pressure and temperature . In a subsequent Volhard cyanide determination, 0.004%- by weight, based on 120.1 g, of cyanide is found. The hydrogen cyanide conversion is thus 99.5%. GC analysis (column: 30 m stable wax, temperature program: 5 minutes isothermal at 5Q°C, subsequent heating to 240oc at 5°C/min, gas chromatograph: Hewlett Packard HP-5890) with internal standard (benzonitrile): 81.7% of 3-pentenonitrile and 2-methyl-3-butenonitrile based on hydrogen cyanide. 3-Pentenonitrile : 2-methyl-3-butenonitrile ratio = 30:1. Example 3 (according to the invention) Hydrocyanation of C4 cut Table 1: Composition of the C4 cut Compound % by vol 1,3-Butadiene 40.50 cis-2-Butene 2.65 traiis-2-Butene 4.30 Isobutene 30.20 1-Butene 14.30 Isobutane 1.10 n-Butane 2.90 Propyne 0.50 Carbon dioxide 0.10 Vinylacetylene 0.35 0.41 g of bis(l,5-cyclooctadiene)nickel(0), 0,80 g of 1,1'-bis(diphenylphosphino)ferrocene and 10 ml of toluene are mixed together in a glass autoclave at room temperature under argon, the reaction mixture immediately becoming reddish brown. After about i hour, a mixture of 39 g of Cj cut with a composition shown in Table 1 and 50 g of toluene is added. The glass autoclave is tightly closed and the mixture is heated to 8OOC, an initial pressure of 3.9 bar being set up. The temperature is kept constant at 80 In a subsequent Volhard cyanide determination, 0.01%, based on 134.1 g, of cyanide is found. The hydrogen cyanide conversion is thus 99.9%. GC analysis (column: 30 m stable wax, temperature program: 5 minutes isothermal at 50°C, subsequent heating to 240 3-Pentenonitrile : 2-methyl-3-butenonitrile ratio = 23.8:1. Example 4 (comparative): Hydrocyanation with triphenylphosphine-based catalyst 6.0 g of toluene, 0.1 g of bis(1,5-cyclooctadiene)nickel(0) and 0.39 g of triphenylphosphine are mixed together in a glass miniautoclave under argon at room temperature. After about 1 hour, first 2.0 g of 1,3-butadiene and then 1.0 g of freshly distilled hydrocyanic acid are added. The glass autoclave is tightly closed and the mixture is maintained at 80°C under autogenous pressure. After reaction for 5 hours, the mixture is allowed to cool and then analyzed. GC analysis (column: 30 m stable wax, temperature program: 5 minutes isothermal at SQoc, subsequent heating to 240°C at 5°C/min, gas chromatograph: Hewlett Packard HP-5890) with internal standard (benzonitrile): 5.7% of 3-pentenonitrile and 2-butenonitrile based on hydrogen cyanide. 3-Pentenonitrile : 2-methyl-3-butenonitrile ratio = 0.91:1. WE CLAIM: 1. A process for preparing mixtures of monoolefmic Cs mononitriies with nonconjugated C = C and C = N bonds by catalytic hydrocyanation of 1, 3-butadiene or a 1, 3-butadiene-containing hydrocarbon mixture under known hydrocyanation conditions, wherein the hydrocyanation takes place in the presence of a catalyst which comprises at least one metallocene-phosphorus (III) - nickel (0) complex which comprises at least one monodentate or bidentate metallocene-phosphorus (III) ligand of the formula I V 4. The process as claimed in any of the preceding claims, wherein at least another ligand selected from halides, amines, carboxylates, acetylacetonate, aryl- or alkylsulfonates, hydride, CO, olefins, dienes, cycloolefms, nitriles, N-containing heterocycles, aromatic and heteroaromatic systems, ethers, PF^ and monodentate, bidentate and multidentate phosphine, phosphinite, phosphonite and phosphite ligands is optionally added. 5. The process as claimed in any of the preceding claims, wherein the metallocene-phosphorus (III) Hgand of the formula I is selected from 1,1 '-bis(diphenylphosphino) ferrocene, 1,1 '-bis(diisopropylphosphino)ferrocene or 1,1 '-bis(dicyclohexylphosphino) ferrocene. 6. The process as claimed in any of the preceding claims, wherein a hydrocarbon mixture with a 1, 3-butadiene content of at least 10% by volume, preferably at least 25% by volume, in particular at least 40% by volume, is employed. 7. The process as claimed in any of the preceding claims, wherein a C4 cut from petroleum processing is employed as 1, 3-butadiene-containing hydrocarbon mixture. 8. The process as claimed in any of the preceding claims, wherein the hydrocyanation is carried out semicontinuously by a) charging a reactor with the hydrocarbon mixture, with or without part of the hydrogen cyanide and a catalyst which has been generated in situ where appropriate, with or without a solvent, b) reacting the mixture at elevated temperature under elevated pressure, with hydrogen cyanide being fed in at the rate of its consumption and c) completing the conversion by subsequent reaction, if required, followed by workup. 9. The process as claimed in any of claims 1 to 7, wherein the hydrocyanation is carried out batchwise with the total amount of hydrogen cyanide being present in stage a) in a process as claimed in claim 8. 10. The process as claimed in any of the preceding claims, wherein the hydrocyanation is carried out at from 0 to 200°C, preferably 50 to 150°C, in particular 70 to 120°C. 11. The process as claimed in any of the preceding claims, wherein the hydrocyanation is carried out under a pressure of from 1 to 200 bar, preferably 1 to 100 bar, in particular 1 to 50 bar and specifically 1 to 16 bar. 12. The process as claimed in any of the preceding claims, wherein the conversion of hydrogen cyanide in the reaction is at least 95%, preferably at least 97%, particularly preferably at least 99%. 13. The process as claimed in any of the preceding claims, wherein the resulting product mixture comprises isomeric pentenonitriles and methylbutenonitriles, such as 3-pentenonitrile, 2-pentenonitrile, 4-pentenonitrile, 2-methyl-2-butenonitrile and 2-methyl-3-butenonitrile. 14. The process as claimed in claim 13, wherein the ratio of the amounts of 3- pentenonitrile to 2-methyl-3-butenonitrile is at least 5:1, preferably at least 10:1. in particular at least 20:1. 15. Aprocessforthepreparationofadiponitrile, which comprises: 1. preparation of a mixftireof Cs mononitriles by a process as claimed in any one of claims 1 to 14. 2. optionally, isomerization of the 2-methyle-3-butenonitrile present in the mixture obtained in step 1) to 3-pentenonitrile and isomerization of the 3- pentenonitrile thus foimed and the 3-pentenonitrile present in the mixture obtained in step 1) to n-pentenonitriles, 3. catalytic hydrocyanation of the mixture obtained in step 1) or the isomerized mixture obtained in step 2) for the preparation of adiponitrile, wherein step 1) and steps 2) and/or 3) take place in the presence of a catalyst as claimed in claim 1, 16. The process as claimed in claim 15, wherein the hydrocyanation of 1, 3-butadiene or of the I, 3-butadiene-containing hydrocarbon mixture to prepare adiponitrile takes place in one stage, without separate workup and isomerization of C5 mononitriles. 17. A process for preparing mixtures of monoolefinic C5 mononitriles substantially as herein described and exemplified.

Documents:

1684-mas-1998 abstract duplicate.pdf

1684-mas-1998 abstract.pdf

1684-mas-1998 claims duplicate.pdf

1684-mas-1998 claims.pdf

1684-mas-1998 correspondence others.pdf

1684-mas-1998 correspondence po.pdf

1684-mas-1998 description (complete) duplicate.pdf

1684-mas-1998 description (complete).pdf

1684-mas-1998 form-19.pdf

1684-mas-1998 form-2.pdf

1684-mas-1998 form-26.pdf

1684-mas-1998 form-4.pdf

1684-mas-1998 form-6.pdf

1684-mas-1998 others.pdf

1684-mas-1998 petition.pdf