EP1682561A1

EP1682561A1 - Use of azeotropically dried nickel(ii) halogenides

Info

Publication number: EP1682561A1
Application number: EP04790947A
Authority: EP
Inventors: Gerd Haderlein; Robert Baumann; Michael Bartsch; Tim Jungkamp; Hermann Luyken; Jens Scheidel; Heinz Schäfer; Wolfgang Siegel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2003-10-30
Filing date: 2004-10-28
Publication date: 2006-07-26
Also published as: WO2005042549A1; DE10351002A1; CN1875027B; JP2007509885A; TW200517180A; CN1875027A; BRPI0416021B1; AR046569A1; US7700795B2; KR101296565B1; BRPI0416021A; KR20070052686A; CA2544051A1; US20070073071A1

Abstract

The invention relates to a method for the production of nickel(0) phosphorous ligand complexes containing at least one nickel(0) central atom and at least one ligand containing phosphorus. One nickel (II) halognenide dried by azeotropic distillation is reduced in the presence of at least one ligand containing phosphorous.

Description

Use of azeotropically dried nickel (II) halides

description

The present invention relates to a process for the preparation of nickel (0) -phosphorus ligand complexes. The present invention furthermore relates to the mixtures containing nickel (0) -phosphorus ligand complexes obtainable by this process and to their use in the hydrocyanation of alkenes or isomerization of unsaturated nitriles.

Nickel complexes of phosphorus ligands are suitable catalysts for the hydrocyanation of alkenes. For example, nickel complexes with monodentate phosphites are known which catalyze the hydrocyanation of butadiene to produce a mixture of isomeric pentenenitriles. These catalysts are also suitable in a subsequent isomerization of the branched 2-methyl-3-butenenitrile to linear 3-pentenenitrile and the hydrocyanation of the 3-pentenenitrile to adiponitrile, an important intermediate in the production of nylon.

No. 3,903,120 describes the production of zero-valent nickel complexes with monodentate phosphite ligands starting from nickel powder. The phosphorus-containing ligands have the general formula PZ ₃ , in which Z corresponds to an alkyl, alkoxy or aryloxy group. This process uses finely divided elemental nickel. In addition, the reaction is preferably carried out in the presence of a nitric solvent and in the presence of an excess of ligand.

No. 3,846,461 describes a process for the preparation of zero-valent nickel complexes with triorganophosphite ligands by reaction of triorganophosphite compounds with nickel chloride in the presence of a finely divided reducing metal which is more electropositive than nickel. The reaction according to US 3,846,461 takes place in the presence of a promoter which is selected from the group consisting of NH ₃ , NH X, Zn (NH ₃ ) ₂ X ₂ and mixtures of NH * X and ZnX ₂ , wherein X is a halide equivalent.

New developments have shown that it is advantageous to use nickel complexes with chelate ligands (multidentate ligands) in the hydrocyanation of alkenes, since they can achieve both higher activities and higher selectivities with increased service life. The prior art methods described above are not suitable for the production of nickel complexes with chelate ligands. However, processes are also known from the prior art which enable the production of nickel complexes with chelate ligands. No. 5,523,453 describes a process for the preparation of nickel-containing hydrocyanation catalysts which contain bidentate phosphorus ligands. These complexes are prepared starting from soluble nickel (0) complexes by re-complexing with chelate ligands. Ni (COD) ₂ or (oTTP) ₂ Ni (C ₂ H ₄ ) are used as starting compounds (COD = 1, 5-cyclooctadiene; oTTP = P (O-ortho-C ₆ H ₄ CH ₃ ) ₃ ). This process is cost-intensive due to the complex production of the nickel starting compounds.

Alternatively, there is the possibility of producing nickel (0) complexes from divalent nickel compounds and chelate ligands by reduction. This method generally requires working at high temperatures, so that thermally labile ligands in the complex may decompose.

US 2003/0100442 A1 describes a process for the production of a nickel (O) chelate complex, in which, in the presence of a chelate ligand and a nitrile-containing solvent, nickel chloride is reduced with a more electropositive metal than nickel, in particular zinc or iron. In order to achieve a high space-time yield, an excess of nickel salt is used, which has to be separated off again after the complexation. The process is usually carried out with water-containing nickel chloride, which can lead to their decomposition, in particular if hydrolysis-labile ligands are used. If one works with anhydrous nickel chloride, in particular when using hydrolysis-labile ligands, it is essential according to US 2003/0100442 A1 that the nickel chloride is first dried by a special process in which very small particles with a large surface area and thus higher Reactivity can be obtained. A disadvantage of the method is in particular that the fine dust of nickel chloride produced by spray drying is carcinogenic. Another disadvantage of this process is that the reaction is generally carried out at elevated reaction temperatures, which can lead to the decomposition of the ligand or the complex, particularly in the case of temperature-labile ligands. Another disadvantage is that an excess of reagents has to be used in order to achieve economic sales. After the reaction has ended, these excesses have to be removed in a complex manner and, if necessary, returned.

GB 1 000477 and BE 621 207 relate to processes for the production of nickel (O) -

Complexes by reduction of nickel (II) compounds using phosphorus-containing ligands.

It was therefore an object of the present invention to provide a process for the preparation of nickel-phosphorus ligand complexes which the process described above

Essentially avoids disadvantages of the prior art. In particular, an anhydrous nickel source is to be used, so that hydrolysis-labile ligands not be decomposed during complexation. In addition, the reaction conditions should preferably be gentle so that temperature-labile ligands and the complexes formed do not decompose. In addition, the method according to the invention should preferably make it possible to use no or only a small excess of the reagents, so that a separation of these substances - after the preparation of the complex - is as unnecessary as possible. The process should also be suitable for the production of nickel (0) complexes with chelate ligands.

The object is achieved according to the invention by a process for the preparation of nickel (0) -phosphorus ligand complexes containing at least one nickel (0) central atom and at least one phosphorus-containing ligand.

The process according to the invention is characterized in that a water-containing nickel (II) halide dried by azeotropic distillation is reduced in the presence of at least one phosphorus-containing ligand.

azeotropic

A water-containing nickel (II) halide is used in the azeotropic distillation. Water-containing nickel (II) halide is a nickel halide which is selected from the group of nickel chloride, nickel bromide and nickel iodide, which contains at least 2% by weight of water. Examples of these are nickel chloride dihydrate, nickel chloride hexahydrate, an aqueous solution of nickel chloride, nickel bromide trihydrate, an aqueous solution of nickel bromide, nickel iodide hydrates or an aqueous solution of nickel iodide. In the case of nickel chloride, nickel chloride hexahydrate or an aqueous solution of nickel chloride is preferably used. In the case of nickel bromide and nickel iodide, the aqueous solutions are preferably used. An aqueous solution of nickel chloride is particularly preferred. ,

In the case of an aqueous solution, the concentration of the nickel (II) halide is in

Water itself is not critical. A proportion of the nickel (II) halide in the total weight of nickel (II) halide and water of at least 0.01% by weight, preferably at least 0.1% by weight, particularly preferably at least 0, has proven advantageous. 25% by weight, particularly preferably at least 0.5% by weight. A proportion of the nickel (II) halide in the total weight of nickel (II) halide and water in the range of at most 80% by weight, preferably at most 60% by weight, particularly preferably at most 40%, has proven advantageous .-% proven. For practical reasons, it is advantageous not to exceed a proportion of nickel halide in the mixture of nickel halide and water which gives a solution under the given temperature and pressure conditions. In the case of an aqueous solution of nickel chloride, it is therefore advantageous for practical reasons to add a proportion of nickel halide to the total weight of nickel chloride and water at room temperature. to be chosen from a maximum of 31% by weight. At higher temperatures, correspondingly higher concentrations can be chosen, which result from the solubility of nickel chloride in water.

The water-containing nickel (II) halide is dried by an azeotropic distillation before the reduction. In a preferred embodiment of the present invention, azeotropic distillation is a process for removing water from the corresponding water-containing nickel (II) halide, to which a diluent is added, the boiling point of which in the case of non-azeotropic formation of the diluent with water under the pressure conditions the distillation mentioned below is higher than the boiling point of water and which is liquid at this boiling point of water or which forms an azeotrope or heteroazeotrope with water under the pressure and temperature conditions of the distillation mentioned below, and the mixture containing the water-containing nickel (II ) -halide and the diluent, with separation of water or said azeotrope or said heteroazeotrope from this mixture and to obtain an anhydrous mixture containing nickel (II) halide and said diluent.

In addition to the water-containing nickel (II) halide, the starting mixture can contain further constituents, such as ionic or nonionic, organic or inorganic compounds, in particular those which are homogeneously miscible with the starting mixture or are soluble in the starting mixture.

According to the invention, the water-containing nickel (II) halide is mixed with a diluent whose boiling point is higher than the boiling point of water under the pressure conditions of the distillation and which is liquid at this boiling point of the water.

The pressure conditions for the subsequent distillation are not critical per se. Pressures of at least 10 ^" MPa, preferably at least 10 ^{" 3} MPa, in particular at least 5 * 10 ^"3 MPa, have proven advantageous. Pressures of at most 1 MPa, preferably at most 5 * 10 ^{" 1} MPa, in particular at most 1, have proven advantageous , 5 * 10 ^"1 MPa.

The distillation temperature is then set depending on the pressure conditions and the composition of the mixture to be distilled. At this temperature the diluent is preferably liquid. For the purposes of the present invention, the term diluent is understood to mean both an individual diluent and a mixture of such diluents, and in the case of such a mixture the physical properties mentioned in the present invention relate to this mixture. Furthermore, under these pressure and temperature conditions the diluent preferably has a boiling point which, in the case of non-azeotrope formation of the diluent with water, is higher than that of water, preferably by at least 5 ° C., in particular at least 20 ° C., and preferably at most 200 ° C, especially at most 100 ° C.

In a preferred embodiment, diluents can be used which form an azeotrope or heteroazeotrope with water. The amount of diluent is not critical per se to the amount of water in the mixture. It is advantageous to use more liquid diluent than the amounts to be distilled off by the azeotropes, so that excess diluent remains as the bottom product.

If a diluent is used which does not form an azeotrope with water, the amount of diluent is not critical per se in relation to the amount of water in the mixture.

The diluent used is in particular selected from the group consisting of organic nitriles, aromatic hydrocarbons, aliphatic hydrocarbons and mixtures of the aforementioned solvents. With regard to the organic nitriles, acetonitrile, propionitrile, n-butyronitrile, n-valeronitrile, cyanocyclopropane, acrylonitrile, crotonitrile, allyl cyanide, cis-2-pentenenitrile, trans-2-pentenenitrile, cis-3-pentenenitrile, trans-3-pentenenitrile 4-pentenenitrile, 2-methyl-3-butenenitrile, Z-2-methyl-2-butenenitrile, E-2-methyl-2-butenenitrile, ethylsuccinitrile, adiponitrile, methylglutaronitrile or mixtures thereof. With regard to the aromatic hydrocarbons, benzene, toluene, o-xylene, m-xylene, p-xylene or mixtures thereof can preferably be used. Aliphatic hydrocarbons can preferably be selected from the group of linear or branched aliphatic hydrocarbons, particularly preferably from the group of cycloaliphatics, such as cyclohexane or methylcyclohexane, or mixtures thereof. Cis-3-pentenenitrile, trans-3-pentenenitrile, adiponitrile, methylglutaronitrile or mixtures thereof are particularly preferably used as solvents.

If an organic nitrile or mixtures containing at least one organic nitrile is used as the diluent, it has proven to be advantageous to choose the amount of diluent such that the proportion of the nickel (II) halide in the finished mixture of the total weight of nickel (II) halide and diluent is at least 0.05% by weight, preferably at least 0.5% by weight, particularly preferably at least 1% by weight.

If an organic nitrile or mixtures containing at least one organic nitrile is used as the diluent, the amount has proven to be advantageous of diluent so that the proportion of nickel (II) halide in the total weight of nickel (II) halide and diluent in the finished mixture is at most 50% by weight, preferably at most 30% by weight, particularly is preferably at most 20% by weight.

According to the invention, the mixture containing the water-containing nickel (II) halide and the diluent is distilled, with the separation of water from this mixture and obtaining an anhydrous mixture containing nickel (II) halide and the said diluent. In a preferred embodiment, the mixture is first prepared and then distilled. In another preferred embodiment, the water-containing nickel halide, particularly preferably the aqueous solution of the nickel halide, is gradually added to the boiling diluent during the distillation. As a result, the formation of a greasy solid which is difficult to handle in terms of process engineering can be substantially avoided.

In the case of pentenenitrile as the diluent, the distillation can advantageously be carried out at a pressure of at most 200 kPa, preferably at most 100 kPa, in particular at most 50 kPa, particularly preferably at most 20 kPa.

In the case of pentenenitrile as diluent, the distillation can preferably be carried out at a pressure of at least 1 kPa, preferably at least 5 kPa, particularly preferably 10 kPa.

The distillation can advantageously be carried out by single-stage evaporation, preferably by fractional distillation in one or more, such as 2 or 3, distillation apparatuses. Equipment suitable for distillation for this purpose, such as those described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 7, John Wiley & Sons, New York, 1979, pages 870-881 , such as sieve plate columns, bubble tray columns, packing columns, packed columns, columns with side take-off or dividing wall columns.

The distillation can be carried out batchwise.

The distillation can be carried out continuously.

ligands

The process according to the invention for the production of nickel (0) -phosphorus ligand complexes, containing at least one nickel (0) central atom and at least one phosphorus-containing ligand, is characterized in that the azeotropically distilled lation dried nickel (II) halide is reduced in the presence of at least one phosphorus-containing ligand.

In the process according to the invention, the phosphorus-containing ligands are preferably selected from the group consisting of phosphines, phosphites, phosphinites and phosphonites.

These phosphorus-containing ligands preferably have the formula I: P (X ¹ R ¹ ) (X ² R ² ) (X ³ R ³ ) (I)

For the purposes of the present invention, compound I is understood to mean a single compound or a mixture of different compounds of the aforementioned formula.

According to the invention, X ¹ , X ² , X ^{3 are} independently oxygen or a single bond. If all of the groups X ¹ , X ² and X ^{3 are} individual bonds, compound I is a phosphine of the formula P (R ¹ R ² R ³ ) with the meanings given for R ¹ , R ² and R ³ in this description ,

If two of the groups X ¹ , X ² and X ^{3 are} individual bonds and one is oxygen, compound I is a phosphinite of the formula P (OR ¹ ) (R ² ) (R ³ ) or P (R ¹ ) (OR ² ) (R ³ ) or P (R ¹ ) (R) (OR ³ ) with the meanings given below for R ² and R ³ .

If one of the groups X ¹ , X ² and X ^{3 stands} for a single bond and two for oxygen, compound I represents a phosphonite of the formula P (OR ¹ ) (OR ² ) (R ³ ) or P (R ¹ ) (OR ² ) (OR ³ ) or P (OR ¹ ) (R ² ) (OR ³ ) with the meanings given for R ² and R ³ in this description.

In a preferred embodiment, all of the groups X ¹ , X ² and X ^{3 should} stand for oxygen, so that compound I is advantageously a phosphite of the formula P (OR ¹ ) (OR ² ) (OR ³ ) with those for R ¹ , R ² and R ³ represents meanings mentioned below.

According to the invention, R ¹ , R ² , R ³ independently of one another represent identical or different organic radicals. R ¹ , R ² and R ³ are, independently of one another, alkyl radicals, preferably having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, Aryl groups, such as phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl, 2-naphthyl, or hydrocarbyl, preferably with 1 to 20 carbon atoms, such as 1,1'-biphenol, 1,1 -Binaphthol into consideration. The groups R ¹ , R ² and R ³ can be connected to one another directly, that is not solely via the central phosphorus atom. be that. The groups R ² and R ³ are preferably not directly connected to one another.

In a preferred embodiment, groups R ¹ , R ² and R ³ are selected from the group consisting of phenyl, o-tolyl, m-tolyl and p-tolyl. In a particularly preferred embodiment, a maximum of two of the groups R ¹ , R ² and R ^{3 should be} phenyl groups.

In another preferred embodiment, a maximum of two of the groups R ² , R ³ and R ^{3 should be} o-tolyl groups.

Particularly preferred compounds I are those of the formula I a

(o-tolyl-O-) _w (m-tolyl-O-) _x (p-tolyl-O-) _y (phenyl-O-) ₂ P (I a)

are used, where w, x, y and z represent a natural number, and the following conditions apply: w + x + y + z = 3 and w, z ≤ 2.

Such compounds I a are, for example, (p-tolyl-O -) (phenyl-O-) ₂ P, (m-tolyl-O -) (phenyl-O-) ₂ P, (o-tolyl-O-) (phenyl -O-) ₂ P, (p-tolyl-O-) ₂ (phenyl-O-) P, (m-tolyl-O-) ₂ (phenyl-O-) P, (o-tolyl-O-) ₂ (Phenyl-O-) P, (m-tolyl-O -) (p-tolyl-O) (phenyl-O-) P, (o-tolyl-O -) (p-tolyl-O -) (phenyl- O-) P, (o-Tolyi-O -) (m-tolyl-O -) (phenyl-O-) P, (p-tolyl-O-) ₃ P, (m-tolyl-O -) (p -Tolyl-O-) ₂ P, (o-tolyl-O -) (p-tolyl-O-) ₂ P, (m-tolyl-O-) ₂ (p-tolyl-O-) P, (o- Tolyl-O-) ₂ (p-tolyl-O-) P, (o-tolyl-O -) (m-tolyl-O -) (p-tolyl-O) P, (m-tolyl-O-) ₃ P, (o-tolyl-O -) (m-tolyl-O-) ₂ P (o-tolyl-O-) ₂ (m-tolyl-O-) P, or mixtures of such compounds.

Mixtures containing (m-tolyl-O-) ₃ P, (m-tolyl-O-) ₂ (p-tolyl-O-) P, (m-tolyl-O -) (p-tolyl-O-) P and (P-tolyl-O-) ₃ P can be obtained, for example, by reacting a mixture containing m-cresol and p-cresol, in particular in a molar ratio of 2: 1, as is obtained in the working up of petroleum by distillation, with a phosphorus trihalide, such as phosphorus trichloride. receive.

In another, likewise preferred embodiment, the phosphites of the formula Ib described in more detail in DE-A 199 53 058 are suitable as phosphorus-containing ligands:

P (OR ¹ ) _x (OR ² ) _y (OR ³ ) _z (OR ⁴ ) _p (I b)

With

R ¹ : aromatic radical with a CrC ^ alkyl substituent in the o-position to the oxygen atom which connects the phosphorus atom to the aromatic system, or with an aromatic substituent in the o-position to the oxygen atom that connects the phosphorus atom to the aromatic system, or with an aromatic system fused in the o-position to the oxygen atom that connects the phosphorus atom to the aromatic system,

R ² : aromatic radical with a C _r C ₁₈ alkyl substituent in the m-position to the oxygen atom that connects the phosphorus atom with the aromatic system, or with an aromatic substituent in the m-position to the oxygen atom that connects the phosphorus atom with the aromatic system connects, or with an aromatic system fused in the m-position to the oxygen atom, which connects the phosphorus atom with the aromatic system, whereby the aromatic remainder in the o-position to the oxygen atom, which connects the phosphorus atom with the aromatic system Carries hydrogen atom,

R ³ : aromatic radical with a CC ₁₈ alkyl substituent in the p-position to the oxygen atom that connects the phosphorus atom to the aromatic system, or with an aromatic substituent in the p-position to the oxygen atom that connects the phosphorus atom to the aromatic system , the aromatic radical in the o-position to the oxygen atom which connects the phosphorus atom to the aromatic system carries a hydrogen atom,

R ⁴ : aromatic radical which, in the o-, m- and p-position to the oxygen atom which connects the phosphorus atom to the aromatic system, bears other substituents than those defined for R ¹ , R ² and R ³ , the aromatic radical bears a hydrogen atom in the o-position to the oxygen atom that connects the phosphorus atom to the aromatic system,

x: 1 or 2,

y, z, p: independently of one another 0, 1 or 2 with the proviso that x + y + z + p = 3.

Preferred phosphites of the formula Ib can be found in DE-A 199 53 058. The radical R ¹ advantageously includes o-tolyl, o-ethyl-phenyl, on-propyl-phenyl, o-isopropyl-phenyl, on-butyl-phenyl, o-sec-butyl-phenyl, o- tert-Butyl-phenyl, (o-PhenyΙ) phenyl or 1-naphthyl groups into consideration.

The radical R ² is m-tolyl, m-ethyl-phenyl, mn-propyl-phenyl, m-isopropyl-phenyl, mn-butyl-phenyl, m-sec-butyl-phenyl, m-tert -Butyl-phenyl-, (m-phenyl) -phenyΙ or 2-naphthyl groups preferred.

The radical R ³ is advantageously p-tolyl, p-ethyl-phenyl, pn-propyl-phenyl, p-isopropyl-phenyl, pn-butyl-phenyl, p-sec-butyi-phenyl-, p- tert-butyl-phenyl- or (p- Phenyl) phenyl groups into consideration.

R ⁴ is preferably phenyl. P is preferably zero. The following options result for the indices x, y, z and p in connection I b:

Preferred phosphites of the formula Ib are those in which p is zero and R ¹ , R ² and R ³ are selected independently of one another from o-isopropylphenyl, m-tolyl and p-tolyl, and R ^{4 is} phenyl.

Particularly preferred phosphites of the formula Ib are those in which R ^{1 is} the o-isopropylphenyl radical, R ^{2 is} the m-tolyl radical and R ^{3 is} the p-tolyl radical with the indices mentioned in the table above; also those in which R ^{1 is} the o-tolyl radical, R ^{2 is} the m-tolyl radical and R ^{3 is} the p-tolyl radical with the indices specified in the table; furthermore those in which R ^{1 is} the 1-naphthyl radical, R ^{2 is} the m-tolyl radical and R ^{3 is} the p-tolyl radical with the indices specified in the table; also those in which R ^{1 is} the o-tolyl radical, R ^{2 is} the 2-naphthyl radical and R ^{3 is} the p-tolyl radical with the indices specified in the table; and finally those in which R ^{1 is} the o-isopropylphenyl radical, R ^{2 is} the 2-naphthyl radical and R ^{3 is} the p-tolyl radical with the indices given in the table; as well as mixtures of these phosphites.

Phosphites of formula I b can be obtained by

a) reacting a phosphorus trihalide with an alcohol selected from the group consisting of R ¹ OH, R ² OH, R ³ OH and R OH or mixtures thereof to give a dihalophosphoric acid monoester,

b) the said dihalophosphoric acid monoester is reacted with an alcohol selected from the group consisting of R ¹ OH, R ² OH, R ³ OH and R OH or mixtures thereof to give a monohalophosphoric acid diester and

c) reacting said monohalophosphoric diester with an alcohol selected from the group consisting of R ¹ OH, R ² OH, R ³ OH and R ⁴ OH or mixtures thereof to obtain a phosphite of the formula Ib. The implementation can be carried out in three separate steps. Two of the three steps can also be combined, i.e. a) with b) or b) with c). Alternatively, all of steps a), b) and c) can be combined with one another.

Suitable parameters and amounts of the alcohols selected from the group consisting of R ¹ OH, R ² OH, R ³ OH and R ⁴ OH or their mixtures can easily be determined by a few simple preliminary tests.

Suitable phosphorus trihalides are in principle all phosphorus trihalides, preferably those in which Cl, Br, I, in particular Cl, is used as the halide, and mixtures thereof. Mixtures of different identical or different halogen-substituted phosphines can also be used as the phosphorus trihalide. PCI ₃ is particularly preferred. Further details on the reaction conditions in the preparation of the phosphites Ib and on the workup can be found in DE-A 199 53 058.

The phosphites Ib can also be used as a ligand in the form of a mixture of different phosphites Ib. Such a mixture can occur, for example, in the production of the phosphites Ib.

However, it is preferred that the phosphorus-containing ligand is multidentate, in particular bidentate. The ligand used therefore preferably has the formula II

on what mean

X ¹¹ , X ¹² , X ¹³ , X ²¹ , X ²² , X ²³ independently of one another oxygen or single bond

R ¹¹ , R ¹² independently of one another the same or different, individual or bridged organic radicals

R ²¹ , R ²² independently of one another are identical or different, individual or bridged organic radicals,

Y bridge group For the purposes of the present invention, compound II is understood to mean a single compound or a mixture of different compounds of the abovementioned formula.

In a preferred embodiment, X ¹¹ , X ¹² , X ¹³ , X ²¹ , X ²² , X ²³ can represent oxygen. In such a case, the bridging group Y is linked to phosphite groups.

In another preferred embodiment, X ¹¹ and X ¹² oxygen and X ^{13 can be} a single bond or X ¹¹ and X ¹³ oxygen and X ^{12 can be} a single bond, so that the phosphorus atom surrounded by X ¹¹ , X ¹² and X ^{13 is the} central atom of a phosphonite. In such a case, X ²¹ , X ²² and X ²³ oxygen or X ²¹ and X ²² oxygen and X ²³ a single bond or X ²¹ and X ²³ oxygen and X ²² a single bond or X ²³ oxygen and X ²¹ and X ²² a single bond or X ²¹ oxygen and X ²² and X ^{23 represent} a single bond or X ²¹ , X ²² and X ^{23 represent} a single bond, so that the phosphorus atom surrounded by X ²¹ , X ²² and X ^{23 represents the} central atom of a phosphite, phosphonite, phosphinite or phosphine, preferably a phosphonite.

In another preferred embodiment, X ¹³ oxygen and X ¹¹ and X ^{12 can be} a single bond or X ¹¹ oxygen and X ¹² and X ^{13 can be} a single bond, so that the phosphorus atom surrounded by X ¹¹ , X ^"12 and X ^{13 is the} central atom of a phosphonite In such a case, X ²¹ , X ²² and X ²³ oxygen or X ²³ oxygen and X ²¹ and X ^ a single bond or X ²¹ oxygen and X ²² and X ²³ a single bond or X ²¹ , X ²² and X ²³ a single bond represent, so that the phosphorus atom surrounded by X ²¹ , X ²² and X ^{23 can be the} central atom of a phosphite, phosphinite or phosphine, preferably a phosphinite.

In another preferred embodiment, X ¹¹ , X ¹² and X ^{13 can represent} a single bond, so that the phosphorus atom surrounded by X ¹¹ , X ¹² and X ^{13 is the} central atom of a phosphine. In such a case, X ²¹ , X ²² and X ²³ oxygen or X ²¹ , X ²² and X ^{23 represent} a single bond, so that the phosphorus atom surrounded by X ²¹ , X ²² and X ^{23 is the} central atom of a phosphite or phosphine, preferably a phosphine , can be.

Suitable bridging groups Y are preferably substituted, for example with CC-alkyl, halogen, such as fluorine, chlorine, bromine, halogenated alkyl, such as trifluoroethyl, aryl, such as phenyl, or unsubstituted aryl groups, preferably those having 6 to 20 carbon atoms in the aromatic system , in particular pyrocatechol, bis (phenol) or bis (naphthol). The radicals R ¹¹ and R ¹² can independently represent the same or different organic radicals. Advantageous R, R ¹ and R ¹² aryl radicals, such preferably having 6 to 10 carbon atoms, are suitable, which may be unsubstituted or mono- or polysubstituted, in particular by C _r C ₄ alkyl, halogen, such as fluorine, chlorine, Bromine, halogenated alkyl such as trifluoromethyl, aryl such as phenyl, or unsubstituted aryl groups.

The radicals R ²¹ and R ²² can independently represent the same or different organic radicals. Advantageously suitable as radicals R ²¹ and R ^{22 are} aryl radicals, preferably those having 6 to 10 carbon atoms, which can be unsubstituted or mono- or polysubstituted, in particular by C 1 -C ₄ -alkyl, halogen, such as fluorine, chlorine, Bromine, halogenated alkyl such as trifluoromethyl, aryl such as phenyl, or unsubstituted aryl groups.

The radicals R ¹¹ and R ¹² can be individually or bridged. The radicals R ²¹ and R ²² can also be individual or bridged. The radicals R ¹¹ , R ² , R ²¹ and R ²² can all be individually, two bridged and two individually or all four bridged in the manner described.

In a particularly preferred embodiment, the compounds of the formula I, II, III, IV and V mentioned in US Pat. No. 5,723,641 are suitable. In a particularly preferred embodiment, the compounds of the formula I, II, III, IV, V, VI and VII mentioned in US Pat. No. 5,512,696, in particular the compounds used there in Examples 1 to 31, come into consideration. In a particularly preferred embodiment, the compounds of the formula I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV and XV mentioned in US Pat. No. 5,821,378, in particular those compounds used there in Examples 1 to 73, into consideration.

In a particularly preferred embodiment, the compounds of the formula I, II, III, IV, V and VI mentioned in US Pat. No. 5,512,695, in particular the compounds used there in Examples 1 to 6, come into consideration. In a particularly preferred embodiment, the compounds of the formula I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII and XIV mentioned in US Pat. No. 5,981,772, in particular those in the examples 1 to 66 compounds used.

In a particularly preferred embodiment, the compounds mentioned in US Pat. No. 6,127,567 and the compounds used there in Examples 1 to 29 are suitable. In a particularly preferred embodiment, the compounds of the formula I, II, IM, IV, V, VI, VII, VIII, IX and X mentioned in US Pat. No. 6,020,516, in particular the compounds used there in Examples 1 to 33, come into consideration. In a particularly preferred embodiment, those described in US Pat. No. 5,959,135 mentioned compounds and compounds used there in Examples 1 to 13 into consideration.

In a particularly preferred embodiment, the compounds of the formulas I, II and III mentioned in US Pat. No. 5,847,191 are suitable. In a particularly preferred embodiment, the compounds mentioned in US Pat. No. 5,523,453, in particular those in formulas 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 and 21 connections shown. In a particularly preferred embodiment, the compounds mentioned in WO 01/14392, preferably those there in the formulas V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XXI, XXII, XXIII compounds shown.

In a particularly preferred embodiment, the compounds mentioned in WO 98/27054 are suitable. In a particularly preferred embodiment, the compounds mentioned in WO 99/13983 are suitable. In a particularly preferred embodiment, the compounds mentioned in WO 99/64155 come into consideration.

In a particularly preferred embodiment, the compounds mentioned in German patent application DE 10038037 come into consideration. In a particularly preferred embodiment, the compounds mentioned in German patent application DE 10046025 come into consideration. In a particularly preferred embodiment, the compounds mentioned in German patent application DE 101 502 85 come into consideration.

In a particularly preferred embodiment, the compounds mentioned in German patent application DE 101 502 86 come into consideration. In a particularly preferred embodiment, the compounds mentioned in German patent application DE 102 071 65 come into consideration. In a further particularly preferred embodiment of the present invention, the phosphorus-containing chelate ligands mentioned in US 2003/0100442 A1 come into consideration.

In a further particularly preferred embodiment of the present invention, the phosphorus-containing chelate ligands mentioned in the unpublished German patent application file number DE 103 50 999.2 dated October 30, 2003 come into consideration.

The compounds I, I a, I b and II described and their preparation are known per se. Mixtures containing at least two of the compounds I, I a, I b and II can also be used as the phosphorus-containing ligand. In a particularly preferred embodiment of the process according to the invention, the phosphorus-containing ligand of the nickel (0) complex and / or the free phosphorus-containing ligand is selected from tritolylphosphite, bidentate phosphorus-containing chelate ligands, and the phosphites of the formula Ib

P (OR ¹ ) _x (OR ² ) _y (OR ³ ) _z (OR ⁴ ) _p (I b)

wherein R ¹ , R ² and R ^{3 are} independently selected from o-isopropyl-phenyl, m-tolyl and p-tolyl, R ^{4 is} phenyl; x is 1 or 2, and y, z, p are independently 0, 1 or 2 with the proviso that x + y + z + p = 3; and their mixtures.

reduction

The process according to the invention for the preparation of nickel (0) -phosphorus ligand complexes, containing at least one nickel (0) central atom and at least one phosphorus-containing ligand, by reduction is preferably carried out in the presence of a solvent. The solvent is in particular selected from the group consisting of organic nitriles, aromatic hydrocarbons, aliphatic hydrocarbons and mixtures of the solvents mentioned above. With regard to the organic nitriles, acetonitrile, propionitrile, n-butyronitrile, n-valeronitrile, cyanocyclopropane, acrylonitrile, crotonitrile, allyl cyanide, cis-2-pentenenitrile, trans-2-pentenenitrile, cis-3-pentenenitrile, trans-3-pentenenitrile, 4-pentenenitrile, 2-methyl-3-butenenitrile, Z-2-methyl-2-butenenitrile, E-2-methyl-2-butenenitrile, ethylsuccinonitrile, adiponitrile, methylglutaronitrile or mixtures thereof. With regard to the aromatic hydrocarbons, benzene, toluene, o-xylene, m-xylene, p-xylene or mixtures thereof can preferably be used. Aliphatic hydrocarbons can preferably be selected from the group of linear or branched aliphatic hydrocarbons, particularly preferably from the group of cycloaliphatics, such as cyclohexane or methylcyclohexane, or mixtures thereof. Cis-3-pentenenitrile, trans-3-pentenenitrile, adiponitrile, methylglutaronitrile or mixtures thereof are particularly preferably used as solvents.

An inert solvent is preferably used.

The concentration of the solvent is preferably 10 to 90% by mass, particularly preferably 20 to 70% by mass, in particular 30 to 60% by mass, in each case based on the finished reaction mixture.

In a particular embodiment of the present invention, the solvent is identical to the diluent which is used in the process according to the invention described above for the preparation of the anhydrous mixture comprising the nickel (II) haemogen and the diluent. In the process according to the invention, the concentration of the ligand in the solvent is preferably 1 to 90% by weight, particularly preferably 5 to 80% by weight, in particular 50 to 80% by weight.

The reducing agent used in the process according to the invention is preferably selected from the group consisting of metals which are more electropositive than nickel, metal alkyls, electric current, complex hydrides and hydrogen.

If a metal which is more electropositive than nickel is used as the reducing agent in the process according to the invention, this metal is preferably selected from the group consisting of sodium, lithium, potassium, magnesium, calcium, barium, strontium, titanium, vanadium, Iron, cobalt, copper, zinc, cadmium, aluminum, gallium, indium, tin, lead and thorium. Iron and zinc are particularly preferred. If aluminum is used as the reducing agent, it is advantageous if it is preactivated by reaction with a catalytic amount of mercury (II) salt or metal alkyl. Triethylaluminum is preferably used for the preactivation in an amount of preferably 0.05 to 50 mol%, particularly preferably 0.5 to 10 mol%. The reducing metal is preferably finely divided, the term "finely divided" meaning that the metal is used in a particle size of less than 10 mesh, particularly preferably less than 20 mesh.

If a metal which is more electropositive than nickel is used as the reducing agent in the process according to the invention, the amount of metal is preferably 0.1 to 50% by weight, based on the reaction mass.

If metal alkyls are used as reducing agents in the process according to the invention, they are preferably lithium alkyls, sodium alkyls, magnesium alkyls, in particular Grignard reagents, zinc alkyls or aluminum alkyls. Aluminum alkyls, such as trimethyl aluminum, triethyl aluminum, tri-isopropyl aluminum or mixtures thereof, in particular triethyl aluminum, are particularly preferred. The metal alkyls can be used in bulk or dissolved in an inert organic solvent such as hexane, heptane or toluene.

If complex hydrides are used as reducing agents in the process according to the invention, preference is given to using metal aluminum hydrides, such as lithium aluminum hydride, or metal borohydrides, such as sodium borohydride.

The molar ratio of the redox equivalents between the nickel (II) source and the reducing agent is preferably 1: 1 to 1: 100, particularly preferably 1: 1 to 1:50, in particular 1: 1 to 1: 5. In the process according to the invention, the ligand to be used can also be present in a ligand solution which has already been used as a catalyst solution in hydrocyanation reactions and is depleted in nickel (O). This "back catalyst solution" generally has the following composition:

2 to 60% by weight, in particular 10 to 40% by weight, of pentenenitrile,

0 to 60% by weight, in particular 0 to 40% by weight, of adiponitrile,

0 to 10% by weight, in particular 0 to 5% by weight, of other nitriles,

- 10 to 90 wt .-%, in particular 50 to 90 wt .-% phosphorus-containing ligand and

- 0 to 2 wt .-%, in particular 0 to 1 wt .-% nickel (O).

The free ligand contained in the back catalyst solution can thus be converted back to a nickel (0) complex by the process according to the invention.

In a particular embodiment of the present invention, the ratio of the nickel (II) source to the phosphorus-containing ligand is 1: 1 to 1: 100. Further preferred ratios of the nickel (II) source to the phosphorus-containing ligand are 1: 1 to 1: 3, especially 1: 1 to 1: 2.

The method according to the invention can be carried out at any pressure. For practical reasons, pressures between 0.1 bara and 5 bara, preferably 0.5 bara and 1.5 bara, are preferred.

The process according to the invention can be carried out in batch mode or continuously.

It is possible to use the nickel (II) ether adduct directly in the solution or suspension thus obtained for the preparation of the nickel (0) -phosphori ligand complexes. Alternatively, the adduct can also first be isolated and optionally dried and dissolved or resuspended again to produce the nickel (0) -phosphorus ligand complex. The adduct can be isolated from the suspension by methods known per se to the person skilled in the art, such as filtration, centrifugation, sedimentation or by hydrocyclones, such as, for example, in Ullmann's Encyclopedia of Industrial Chemistry, Unit Operation I, Vol. B2, VCH, Weinheim, 1988, chapter 10, pages 10-1 to 10-59, chapter 11, pages 11-1 to 11-27 and chapter 12, pages 12-1 to 12-61. In the process according to the invention, it is possible to work without excess nickel (II) halide or reducing agent, for example zinc, so that it is not necessary to separate them after the nickel (0) complex has formed.

In a particular embodiment of the present invention, the method according to the invention comprises the following method steps:

(1) drying a water-containing nickel (II) halide by azeotropic distillation,

(2) precomplexing the azeotropically dried nickel (II) halide in a solvent in the presence of a phosphorus-containing ligand,

(3) adding at least one reducing agent to the solution or suspension originating from process step (2) at an addition temperature of 20 to 120 ° C.,

(4) stirring the suspension or solution from process step (3) for at a reaction temperature of 20 to 120 ° C.

The pre-complexing temperatures, addition temperatures and reaction temperatures can, independently of one another, be 20 ° C. to 120 ° C. Temperatures of 30 ° C. to 80 ° C. are particularly preferred in the pre-complexing, addition and reaction.

The pre-complexation periods, addition periods and implementation periods can, independently of one another, be 1 minute to 24 hours. The pre-complexation period is in particular 1 minute to 3 hours. The addition period is preferably 1 minute to 30 minutes. The reaction period is preferably 20 minutes to 5 hours.

The present invention furthermore relates to the solutions containing nickel (0) -phosphorus ligand complexes obtainable by the process according to the invention and to their use in the hydrocyanation of alkenes and unsaturated nitriles, in particular in the hydrocyanation of butadiene for the preparation of a mixture of pentenenitriles and the hydrocyanation of pentenenitriles to adiponitrile. The present invention also relates to their use in the isomerization of alkenes and unsaturated nitriles, in particular of 2-methyl-3-butenenitrile to 3-pentenenitrile.

The present invention further provides a process for the preparation of a nickel (II) halide dried by azeotropic distillation by removing water from mixtures comprising at least one water-containing nickel (II) halide, the mixture being mixed with a diluent whose boiling point in the case of non-azeotropic formation of the said diluent with water under the pressure conditions of the distillation mentioned below is higher than the boiling point of water and which is liquid at this boiling point of water or that Forms azeotropically or heteroazeotropically with water under the pressure and temperature conditions of the distillation mentioned below, and the mixture containing the water-containing nickel (II) halide and the diluent, with the separation of water or said acetrope or said heteroazeotrope therefrom Mixture and to obtain an anhydrous mixture containing nickel (II) halide and said diluent is distilled. Further designs and refinements of this method have already been described above.

The present inventions are explained in more detail using the following exemplary embodiments.

embodiments

In the examples for complex synthesis, a solution of chelate phosphonite 1 was used as the chelating ligand solution

in 3-pentenenitrile (65% by weight chelate, 35% by weight 3-pentenenitrile).

To determine the conversion, the complex solutions produced were examined for their content of active, complexed Ni (0). For this purpose, the solutions were mixed with tri (m / p-tolyl) phosphite (typically 1 g phosphite per 1 g solution) and kept at 80 ° C. for about 30 minutes in order to achieve complete re-complexing. The current-voltage curve was then measured in a still solution against a reference electrode for electrochemical oxidation in a cyclic voltammetric measuring apparatus, which determines the peak current proportional to the concentration and over a calibration with solutions of known Ni (0) concentrations of the Ni (0) content of the test solution - corrected for the subsequent dilution with tri (m / p-tolyl) phosphite - determined. The Ni (0) values mentioned in the examples indicate the Ni (0) content, determined by this method, in% by weight, based on the total reaction solution.

Examples 1-4 describe the preparation of the suspensions with subsequent complex formation:

Example 1:

9.7 g of NiCl ₂ -6H ₂ O (41 mmol) in 100 ml of 3-pentenenitrile were suspended in a 250 ml flask with stirrer and water separator. The mixture was heated to boiling under reflux and the water was removed. A fine suspension in 3-pentenenitrile was obtained. The suspension was evaporated almost to dryness, resuspended in 13 g of 3-pentenenitrile and mixed with 100 g of chelate solution (86 mmol ligand). 4 g of Zn powder (61 mmol, 1.4 eq.) Were added at 50 ° C., the mixture was heated to 60 ° C. and stirred for 3 h. Since no conversion was observed, stirring was continued at 80 ° C. for 3 h. An Ni (0) value of 1.1% (56% conversion) was measured.

Example 2:

A solution of 9.7 g NiCl ₂ -6H ₂ O (41 mmol) in 10 g water was mixed with 150 g 3-pentenenitrile in a 500 ml flask equipped with a stirrer and a water separator. The two-phase mixture was heated to boiling under reflux and the water was removed in the process. A fine suspension in 3-pentenenitrile was obtained. The suspension was evaporated almost to dryness, resuspended in 13 g of 3-pentenenitrile and mixed with 100 g of chelate solution (86 mmol ligand). 4 g of Zn powder (61 mmol, 1.4 eq.) Were added at 80 ° C. and the mixture was stirred for 6 h. An Ni (0) value of 1.4% (71% conversion) was measured.

Example 3:

A suspension prepared analogously to Example 2 was evaporated almost to dryness, resuspended in 3 g of 3-pentenenitrile and mixed with 50 g of chelate solution (43 mmol ligand). 4 g of Zn powder (61 mmol, 1.4 eq.) Were added at 80 ° C. and the mixture was stirred for 4 h. An Ni (0) value of 2.3% (60% conversion) was measured.

Example 4:

A solution of 19.7 g of NiCl ₂ -6H ₂ O (83 mmol) in 20 g of water was mixed with 61 g of 3-pentenenitrile in a 250 ml flask equipped with a stirrer and water separator. The two-phase mixture was heated to boiling under reflux and the water was removed in the process. A thick, just stirrable suspension in 3-pentenenitrile was obtained. The suspension was cooled to 80 ° C. with 100 g of chelate solution (86 mmol ligand) was added. 8 g of Zn powder (122 mmol, 1.4 eq.) Were then added at 80 ° C. and the mixture was stirred for 4 h. An Ni (0) value of 1.2% (45% conversion) was measured.

Examples 5 and 6 describe the separate preparation of a NiCl ₂ suspension.

Example 5:

A solution of 194 g of NiCl ₂ -6H ₂ O (816 mmol) in 100 g of water was mixed with 300 g of 3-pentenenitrile in a 2 l flask equipped with a stirrer and water separator. The two-phase mixture was heated to boiling under reflux and the water was removed in the process. After 161 g of water (86% of the theoretical amount) had been separated off, the suspension in the flask was partly so viscous and partly solidified into large solid agglomerates that the experiment had to be stopped.

Example e:

700 g of 3-pentenenitrile were heated to boiling under reflux in a 2 l flask with stirrer, water separator and dropping funnel. A solution of 194 g of NiCl ₂ -6H ₂ O (816 mmol) in 105 g of water was added dropwise to this boiling pentenenitrile just as quickly as the water was separated off again in the water separator. A fine, almost homogeneous suspension in 3-pentenenitrile was obtained.

Examples 7-12 describe the preparation of the nickel complexes from a separately prepared suspension.

Example 7:

In a 500 ml flask equipped with a stirrer, 74 g of a suspension (83 mmol of NiCl) prepared according to Example 6 were mixed with 100 g of chelate solution (86 mmol of ligand) under argon and stirred at 80 ° C. for 15 minutes. 8 g of Zn powder (122 mmol, 1.5 eq.) Were then added at 80 ° C. and the mixture was stirred at 80 ° C. for 5 h. An Ni (0) value of 1.7% (64% conversion) was measured.

Example 8:

In a 250 ml flask equipped with a stirrer, 37 g of a suspension (42 mmol of NiCl ₂ ) prepared according to Example 6 were mixed with 50 g of chelate solution (43 mmol of ligand) under argon and stirred at 50 ° C. for 15 minutes. 3 g of Zn powder (46 mmol, 1.1 eq.) Were then added at 50 ° C. and the mixture was stirred at 50 ° C. for 5 h. An Ni (0) value of 1.2% (43% conversion) was measured.

Example 9: A reaction was carried out analogously to Example 8, but the temperature was raised to 80 ° C. before the Zn powder was added. After 5 h, a Ni (0) value of 1.4% (50% conversion) was measured. Example 10:

A reaction was carried out analogously to Example 8, but all steps were carried out at 80.degree. After 5 h, a Ni (0) value of 1.8% (61% conversion) was measured.

Example 11:

A reaction was carried out analogously to Example 7, but 6.8 g of Fe powder (122 mmol, 1.5 eq.) Were added instead of Zn powder. After 5 h, a Ni (0) value of 1.2% (53% conversion) was measured.

Example 12:

In a 250 ml flask equipped with a stirrer, 47.6 g of a suspension (53 mmol of NiCl ₂ ) prepared according to Example 6 were suspended in 67.3 g of chelate solution (58 mmol of ligand) under argon and cooled to 0.degree. Then 26.5 g of a 25% solution of triethyl aluminum in toluene (58 mmol) were slowly metered in. After the solution had been warmed to room temperature, the mixture was stirred for a further 10 h. An Ni (0) value of 0.64% (28% conversion) was measured.

In example 13, a "back catalyst solution" was used as the ligand solution, which had already been used as a catalyst solution in hydrocyanation reactions and had been strongly depleted in Ni (0). The composition of the solution is about 20% by weight of pentenenitriles, about 6% by weight .-% adiponitrile, approx. 3% by weight other nitriles, approx. 70% by weight ligand (consisting of a mixture of 40 mol% chelate phosphonite 1 and 60 mol% tri (m / p-tolyl) phosphite) and a nickel (O) content of only 0.8%.

Example 13:

In a 250 ml flask equipped with a stirrer, 37 g of a suspension (42 mmol of NiCl ₂ ) prepared according to Example 6 were mixed with 50 g of back catalyst solution and stirred at 80 ° C. for 15 minutes. Then 3 g of Zn powder at 80 ° C.

(46 mmol, 1.1 eq.) Were added and the mixture was stirred at 80 ° C. for 5 h. An Ni (0) value of 1.64% (corresponding to a ratio of P: Ni of 4: 1) was measured.

In Examples 14 to 19, tri (m / p-tolyl phosphite) was used as the ligand.

Example 14:

In a 250 ml flask equipped with a stirrer, 36 g (100 mmol) of tri (m / p-tolyl) phosphite were added to 100 g of a suspension (25 mmol of NiCl ₂ ) prepared in analogy to Example 6 under argon and 5 minutes at 80 ° C stirred. Then 1.8 g of Zn powder (28 mmol, 1.1 eq.) Were added at 80 ° C. and the mixture was stirred at 80 ° C. for 4 h. An Ni (0) value of 0.75% (72% conversion) was measured. Example 15:

A reaction was carried out analogously to Example 14, but 53.8 g

(152 mmol) tri (m / p-tolyl phosphite) used. An Ni (0) value of 0.8% (85%

Sales).

Example 16:

A reaction was carried out analogously to Example 15, but all process steps were carried out at 40.degree. An Ni (0) value of 0.6% (65% conversion) was measured.

Example 17:

A reaction was carried out analogously to Example 15, but all process steps were carried out at 60.degree. An Ni (0) value of 0.95% (99% conversion) was measured.

Example 18:

A reaction was carried out analogously to Example 14, but 71.8 g

(203 mmol) tri (m / p-tolyl phosphite) used. An Ni (0) value of 0.5% (85%

Sales).

In the comparative examples, commercially available, anhydrous nickel chloride was used as the nickel source.

Comparative Example 1: In a 500 ml flask equipped with a stirrer, 11 g (85 mmol) of NiCl _{2 were} suspended in 13 g of 3-pentenenitrile under argon, 100 g of chelate solution (86 mmol of ligand) were added and the mixture was stirred at 80 ° C. for 15 minutes , After cooling to 40 ° C., 8 g of Zn powder (122 mmol, 1.4 eq.) Were added and the mixture was stirred at 40 ° C. for 4 h. An Ni (0) value of 0.05% (1% conversion) was measured.

Comparative Example 2:

A reaction was carried out analogously to Comparative Example 1, but the temperature was kept at 80 ° C. when the Zn powder was added. After 5 h, a Ni (0) value of 0.4% (10% conversion) was measured.

Comparative Example 3:

In a 500 ml flask equipped with a stirrer, 11 g (85 mmol) of NiCl _{2 were} suspended in 13 g of 3-pentenenitrile under argon, 100 g of chelate solution (86 mmol of ligand) were added and the mixture was stirred at 80 ° C. for 15 minutes. After cooling to 60 ° C, 5.3 g of Zn powder (95 mmol, 1.1 eq.) Were added and the mixture was stirred at 60-65 ° C for 10 h. An Ni (0) value of 0.16% (4% conversion) was measured. Comparative Example 4:

A reaction was carried out analogously to Comparative Example 3, but the temperature was kept at 80 ° C. when the Fe powder was added. After 10 h, a Ni (0) value of 0.4% (10% conversion) was measured.

Claims

claims

1. A process for the preparation of nickel (0) -phosphorus ligand complexes containing at least one nickel (0) central atom and at least one phosphorus-containing ligand, characterized in that a nickel (II) halide dried by azeotropic distillation in the presence of at least one phosphorus-containing ligand is reduced.

2. The method according to claim 1, characterized in that the nickel (II) halides are selected from the group consisting of nickel (II) chloride, nickel (II) bromide and nickel (II) iodide.

3. The method according to claim 1 or 2, characterized in that the nickel (II) halide dried by azeotropic distillation is produced by a method for removing water from the corresponding water-containing nickel (II) halide, the mixture being mixed with a diluent is added, the boiling point of which in the case of non-azeotrope formation of the diluent mentioned with water under the pressure conditions of the distillation mentioned below is higher than the boiling point of water and which is liquid at this boiling point of the water or an azeotrope or heteroazeotrope with water under the pressure - And temperature conditions of the distillation mentioned below, and the mixture containing the water-containing nickel (II) halide and the diluent, with the separation of water or said acetropic or said heteroazeotrope from this mixture and to obtain an anhydrous mixture containing nickel (II) - halide and the said diluent is distilled.

4. The method according to claim 3, characterized in that the diluent is an organic diluent with at least one nitrile group.

5. The method according to any one of claims 1 to 4, characterized in that metals which are more electropositive than nickel are used as reducing agents.

6. The method according to any one of claims 1 to 4, characterized in that metal alkyls, electric current, complex hydrides or hydrogen are used as the reducing agent.

7. The method according to any one of claims 1 to 6, characterized in that the ligands are selected from the group consisting of phosphines, phosphites, phosphinites and phosphonites.

8. The method according to claim 7, characterized in that the ligand is bidentate.

9. The method according to any one of claims 1 to 8, characterized in that the phosphorus-containing ligand is contained in a catalyst solution which has already been used in hydrocyanation reactions.

10. Mixtures containing nickel (0) -phosphorus ligand complexes, obtainable by a process according to any one of claims 1 to 9.

11. Use of the mixtures containing nickel (0) -phosphorus ligand complexes according to claim 10 in the hydrocyanation and isomerization of alkenes and in the hydrocyanation and isomerization of unsaturated nitriles.

12. A process for the preparation of a nickel (II) halide dried by azeotropic distillation by removing water from mixtures comprising at least one water-containing nickel (II) halide, the mixture being mixed with a diluent whose boiling point in the case of non-aze- The isotropic formation of the diluent mentioned with water under the pressure conditions of the distillation mentioned below is higher than the boiling point of water and which is liquid at this boiling point of the water, or an azeotrope or heteroazeotrope with water under the pressure and temperature conditions of the following Distillation forms, and the mixture containing the water-containing nickel (II) halide and the diluent, with the separation of water or said acetrope or said heteroazeotrope from this mixture and to obtain an anhydrous mixture containing nickel (II) - halide and the said diluent tel is distilled.