WO2008028843A1 - Method for producing dinitriles - Google Patents

Abstract

The invention relates to a method for producing mixtures containing adiponitrile, characterised by the following method steps: a) reaction of 3-pentenenitrile with hydrogen cyanide in the presence of a hydrocyanation catalyst, a promoter and a solvent, to give a hydrocyanation product, containing 3-pentenenitrile, adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the solvent, the hydrocyanation catalyst, the promoter and possible decomposition products from the catalyst, b) distillation of the hydrocyanation product from step a) to give a stream (1) as top product, containing 3-pentenenitrile and a stream (2) as bottom product, containing adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the majority of the solvent, the hydrocyanation catalyst, and the promoter, c) extraction of the stream (2) with an extracting agent to give a stream (3), containing the majority of the solvent, the hydrocyanation catalyst and the extraction agent and a stream (4), containing the majority of the adiponitrile, methylglutaronitrile, ethylsuccinonitrile and promoter.

Description

 Process for the preparation of dinitriles

description

The present invention relates to a process for the preparation of adiponitrile-containing mixtures.

Adiponitrile is an important starting material in nylon production obtained by double hydrocyanation of 1,3-butadiene. In a first hydrocyanation, 1, 3-butadiene is hydrocyanated to 3-pentenenitrile. In a second subsequent hydrocyanation, 3-pentenenitrile is reacted with HCN to give adiponitrile. Both hydrocyanations are catalyzed by nickel (0) complexes with phosphorus ligands.

In the second hydrocyanation of 3-pentenenitrile to adiponitrile, a mixture of the reactant and product nitriles with the catalyst is obtained. Since the reaction product is high-boiling and a thermal load of the catalyst is to be avoided, the reaction mixture must be worked up usually extractive.

Thus, US Pat. No. 3,773,809 describes the hydrocyanation of 3-pentenenitrile or 4-pentenenitrile in the presence of a catalyst system of nickel (O) and a ligand system complexing it, comprising monophosphines or monophosphites, a nitrile and further compounds as catalyst promoters. The resulting product mixture is treated under defined conditions in an extractor with a hydrocarbon, wherein a multiphase system is formed. One phase of this multiphase system contains the hydrocarbon, the nickel (0) complex and the majority of the phosphorus-containing compounds, while the organic mononitrile, the organic dinitrile, decomposed nickel catalyst, decomposed phosphorus-containing compounds and catalyst promoters are essentially in the other phase are included. The hydrocarbon phase is separated off. From the other phase, organic mononitrile, organic dinitrile and catalyst promoters are separated from the decomposed nickel catalyst and the decomposed phosphorus-containing compounds.

The German patent application DE 103 1 1 122 "Process for the hydrocyanation of an olefinically unsaturated compound" of BASF AG proceeds from the fundamental problem that in a hydrocyanation of pentenenitriles in the extraction of the entire product and catalyst flow must be extracted, resulting in very large The solution provided for this purpose is that hydrocarbon is already present during the hydrocyanation, which forms a second phase after the hydrocyanation, take up a large part of the catalyst and can be returned directly to the reactors, ie without having to go through the complete extraction.

DE 103 1 1 122 moreover describes that the proportion of adiponitrile in the mixture to be extracted must be a minimum value, so that, in principle, a phase separation occurs.

In general, it is advantageous for the phase ratio of the extraction if the proportion of 3-pentenenitrile in the hydrocyanation system is low. Ideally, i. From the point of view of extraction (phase ratio and extraction coefficient), it is accordingly advantageous that no 3-pentenenitrile is present any more in the hydrocyanation mixture. For this, however, the 3-pentenenitrile would have to be completely separated before the extractive workup, for example by distillation. In the known methods, however, this will result in that the thermal stress of the catalyst is too high due to the high bottom temperatures in the distillative removal of 3-pentenenitrile, which leads to a decomposition of the catalyst, and leads to that obtained after extraction Catalyst is obtained almost solvent-free. The solvent-free catalyst would have without 3-pentenitrile but so high viscosities that it could not be promoted in a technical process and possibly crystallize out. Optionally, it can be diluted again with 3-pentenenitrile in order to avoid crystallization of the catalyst.

The present invention is accordingly based on the object of providing a process which comprises separating the nickel (0) complex used in the hydrocyanation of 3-pentenenitrile with phosphorus ligands as catalyst from the product of the hydrocyanation, adiponitrile and unreacted starting material, preferably with the possibility of reuse of the catalyst, in particular in said hydrocyanation, in a technically simple and economical manner.

This object is achieved by a process for the preparation of adiponitrile-containing mixtures, which is characterized by the present process steps: a) reaction of 3-pentenenitrile with hydrogen cyanide in the presence of a hydrocyanation catalyst, a promoter and a diluent to obtain a Hydrocyanierungsaustrages, the 3rd Pentenenitrile, adiponitrile, methylglutarditrile, ethylsuccinonitrile, the diluent, the hydrocyanation catalyst, the promoter and optionally decomposition products of the catalyst; b) distilling the hydrocyanation effluent from step a) to obtain a stream 1 overhead product containing 3-pentenenitrile and a stream 2 bottoms product containing adiponitrile, methylglutaronitrile, ethylsuccinonitrile, most of the diluent, hydrocyanation catalyst and promoter; c) extraction of stream 2 with an extractant to obtain a stream 3 containing the major part of the diluent, the hydrocyanation catalyst and the extractant and a stream 4 containing the major part of the adiponitrile, methylglutaronitrile, ethylsuccinonitrile and the promoter.

The inventive method is explained in more detail by Figure 1, wherein the reference numerals 1 to 8 have the following meanings:

1 stage a), starting materials

2 step b)

3 stream 1, containing 3-pentenenitrile

4 stream 2 containing adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the diluent, the hydrocyanation catalyst and the promoter, 5 step c)

6 stream 3, containing the major part of the diluent, the hydrocyanation catalyst and the extractant

7 stream 4 containing most of the adiponitrile, methylglutaronitrile, ethylsuccinonitrile and the promoter 8 extractant

In process step (a), 3-pentenenitrile is reacted with hydrogen cyanide in the presence of a hydrocyanation catalyst, a promoter and a diluent to give a hydrocyanation output, 3-pentenenitrile, adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the diluent, the hydrocyanation catalyst, the promoter and optionally degradation products of the catalyst.

For the purposes of the present invention, the term 3-pentenenitrile is understood to mean trans-3-pentenenitrile or mixtures which comprise trans-3-pentenenitrile, cis-3-pentenenitrile and 4-pentenenitrile. In this case, individual isomers can not be included. In addition, in the mixture, cis- and / or trans-2-pentenenitrile, E and / or Z-2-methylbutenenitrile, 2-methyl-3-butenenitrile in a content of 0-10 wt .-%, preferably 0 to 5 wt .-%, be contained. In a preferred embodiment of the process according to the invention, a mixture of isomeric pentenenitriles is used as 3-pentenenitrile.

The educt stream used in the present process is present with respect to 3-pentenenitrile in a purity of> 80%, preferably> 90%, particularly preferably> 95%.

The 3-pentenenitrile used here preferably originates from a homogeneous hydrocyanation of 1,3-butadiene in the presence of a nickel (0) catalyst with phosphorus-containing ligands, which is known per se to the person skilled in the art.

The catalyst used in process step a) is preferably a mixture of at least one Ni (0) complex with phosphorus-containing ligands and free phosphorus-containing ligands.

In the catalyst thus defined, the molar ratio of P atoms to Ni (O) is preferably 40: 1 to 2: 1, more preferably 15: 1 to 4: 1.

The Ni (0) concentration in the hydrocyanation is generally 0.1-5% by weight, preferably 0.1-3% by weight, particularly preferably 0.1-2.0% by weight.

The nickel (0) complexes which are preferably used as catalyst and contain phosphorus-containing ligands and / or free phosphorus-containing ligands are preferably homogeneously dissolved nickel (0) complexes.

The phosphorus-containing ligands of the nickel (0) complexes and the free phosphorus-containing ligands which are removed by extraction according to the invention are preferably selected from mono- or bidentate 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 be a single compound or a mixture of different compounds of the aforementioned formula. O

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

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

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

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

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

In a preferred embodiment, groups R ¹ , R ² and R ^{3 are} radicals 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 ¹ , R ² and R ^{3 should be} o-tolyl groups.

As particularly preferred compounds I, those of the formula I a

(o-tolyl-O-) _w (m-tolyl-O-) _x (p-tolyl-O-) _y (phenyl-O-) _z P (I a) where w, x, y and z are a natural number and the following conditions apply: w + x + y + z = 3 and w, z <2.

Such compounds Ia 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-tolyl-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-toluyl-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 -olyl-O-) ₂ (p-tolyl-O-) P, (m-tolyl-O -) (p-tolyl-O) ₂ P and (P-Tolyl-O-) ₃ P can be obtained, for example, by reacting a mixture comprising m-cresol and p-cresol, in particular in a molar ratio of 2: 1, as obtained in the distillative work-up of crude oil, with a phosphorus trihalide, such as phosphorus trichloride, receive.

In another, likewise preferred embodiment, the phosphites of the formula Ib which are 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 having a Ci-Ci ₈ -Alkylsubstituenten in o-position to the oxygen atom which connects the phosphorus atom with the aromatic system, or with an aromatic substituent in o-position to the oxygen atom, the phosphorus atom with the aromatic system or with an aromatic system fused to the oxygen atom linking the phosphorus atom to the aromatic system,

R ² : aromatic radical having a Ci-Ci ₈ -Alkylsubstituenten in m-position to the oxygen atom which connects the phosphorus atom with the aromatic system, or with an aromatic substituent in the m-position to the oxygen atom, the phosphorus atom with the aromatic system , or with an aromatic system fused in the m-position to the oxygen atom linking the phosphorus atom to the aromatic system, the aromatic radical being in the ortho position to the oxygen atom linking the phosphorus atom to the aromatic system , carries a hydrogen atom, R 3. aromatic radical having a Ci-Ci ₈ -Alkylsubstituenten in p-position to the oxygen atom which connects the phosphorus atom with the aromatic system, or with an aromatic substituent in p-position to the oxygen atom, the phosphorus atom with the aromatic system wherein the aromatic radical in the position ortho to the oxygen atom which links the phosphorus atom to the aromatic system bears a hydrogen atom,

R ⁴ 4 :. aromatic radical which carries in the o-, m- and p-position to the oxygen atom which connects the phosphorus atom to the aromatic system, other than the substituents defined for R ¹ , R ² and R ³ , wherein the aromatic radical in o- Position to the oxygen atom connecting the phosphorus atom to the aromatic system carries a hydrogen atom,

x: 1 or 2,

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

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

As the radical R ² are m-tolyl, m-ethyl-phenyl, mn-propyl-phenyl, m-isopropyl-phenyl, mn-butyl-phenyl, m-sec-butyl-phenyl, m-tert Butyl-phenyl, (m-phenyl) -phenyl or 2-naphthyl groups are preferred.

As radical R ³ are advantageously p-tolyl, p-ethyl-phenyl, pn-propyl-phenyl, p-isopropyl-phenyl, pn-butyl-phenyl, p-sec-butyl-phenyl, p- tert-butyl-phenyl or (p-phenyl) -phenyl groups into consideration.

Radical R ⁴ is preferably phenyl. Preferably, p is equal to zero. For the indices x, y, z and p in connection I b the following possibilities arise:

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

Particularly preferred phosphites of the formula I b are those in which R ^{1 is} the

Isopropylphenyl radical, R ^{2 is} the m-tolyl radical and R ^{3 is} the p-tolyl radical having 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 having the indices mentioned 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 having the indices mentioned 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 having the indices mentioned in the table; and finally those in which R ^{1 is} the o-isopropyl-phenyl radical, R ^{2 is} the 2-naphthyl radical and R ^{3 is} the p-tolyl radical having the indices mentioned in the table; as well as mixtures of these phosphites.

Phosphites of the 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 ⁴ OH or mixtures thereof

Obtaining a dihalophosphoric acid monoester,

b) reacting said dihalophosphoric acid monoester with an alcohol selected from the group consisting of R ¹ OH, R ² OH, R ³ OH and R ⁴ OH or their mixtures to give a monohalophosphoric diester and

c) reacting said Monohalogenophosphorigsäurediester 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 formula I b.

The reaction can be carried out in three separate steps. Likewise, two of the three steps can be combined, ie a) with b) or b) with c). Alternatively, all of steps a), b) and c) can be combined with each other.

In this case, one can easily determine 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 mixtures thereof by a few simple preliminary experiments. As phosphorus trihalogenide are basically all phosphorus trihalides, preferably those in which as the halide Cl, Br, I, in particular Cl, is used, and mixtures thereof. It is also possible to use mixtures of different identically or differently halogen-substituted phosphines as the phosphorus trihalide. Particularly preferred is PCI ₃ . Further details on the reaction conditions in the preparation of phosphites I b and for workup can be found in DE-A 199 53 058.

The phosphites I b can also be used in the form of a mixture of different phosphites I b as a ligand. Such a mixture can be obtained, for example, in the preparation of phosphites I b.

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

^R "- ^χ " \, _{3 23} / ^{χ21 "R21}

P-X-Y-X -P

RK ¹² -XY ¹² XY ²² - RK ²² _{(| |)}

in which mean

X ¹¹ , X ¹² , X ¹³ , X ²¹ , X ²² , X ^{23 are} independently oxygen or single bond

R ¹¹ , R ^{12 are} independently identical or different, single 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 be a single compound or a mixture of different compounds of the aforementioned formula.

In a preferred embodiment, X ¹¹ , X ¹² , X ¹³ , X ²¹ , X ²² , X ^{23 may be} oxygen. In such a case, the bridging group Y is linked to phosphite groups. In another preferred embodiment, X ¹¹ and X ^{12 can be} oxygen and X ^{13 is} a single bond or X ¹¹ and X ^{13 is} oxygen and X ^{12 is} a single bond such 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 may be} 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 is} 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 central atom of a phosphite, phosphonite, phosphinite or phosphine, preferably of a phosphonite.

In another preferred embodiment, X ¹³ may be oxygen and X ¹¹ and X ^{12 may be} a single bond or X ¹¹ oxygen and X ¹² and X ^{13 may be} a single bond such that the phosphorous 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 can be} oxygen or X ²³ oxygen and X ²¹ and X ²² 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 in 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 of a phosphinite.

In another preferred embodiment, X ¹¹ , X ¹² and X ^{13 may represent} a single bond such 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 may represent} a single bond such 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.

Bridging group Y is preferably substituted, for example, with C 1 -C ₄ -alkyl, halogen, such as fluorine, chlorine, bromine, halogenated alkyl, such as trifluoromethyl, 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 may independently represent identical or different organic radicals. Advantageously suitable radicals R ¹¹ and R ^{12 are} aryl radicals, preferably those having 6 to 10 carbon atoms, which may be unsubstituted or monosubstituted 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 ²¹ and R ²² may independently represent identical or different organic radicals. Advantageously suitable radicals R ²¹ and R ^{22 are} aryl radicals, preferably those having 6 to 10 carbon atoms, which may be unsubstituted or monosubstituted or polysubstituted, in particular by C 1 -C ₄ -alkyl, halogens, 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 may be singly or bridged. The radicals R ²¹ and R ²² may also be singly or bridged. The radicals R ¹¹ , R ¹² , R ²¹ and R ²² may all be singly, 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, are suitable. 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 mentioned therein considered in Examples 1 to 73 compounds.

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, are suitable. 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 mentioned therein into consideration in Examples 1 to 66.

In a particularly preferred embodiment, the compounds mentioned in US Pat. No. 6,127,567 and compounds used there in Examples 1 to 29 are suitable. In a particularly preferred embodiment, the compounds of the formula I, II, III, 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, are suitable. In a particularly preferred embodiment, the compounds mentioned in US Pat. No. 5,959,135 and compounds used there in Examples 1 to 13 are suitable.

In a particularly preferred embodiment, the compounds of the formula 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 formula 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, are obtained there , 16, 17, 18, 19, 20 and 21 shown compounds, into consideration. In a particularly preferred embodiment, the compounds mentioned in WO 01/14392, preferably those in formula V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XXI, XXII, XXIII compounds, into consideration.

In a particularly preferred embodiment, the compounds mentioned in WO 98/27054 come into consideration. In a particularly preferred embodiment, the compounds mentioned in WO 99/13983 come into consideration. 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 100 380 37 come into consideration. In a particularly preferred embodiment, the compounds mentioned in the German patent application DE 100 460 25 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 chelating ligands mentioned in the German patent application DE 103 50 999.2 of 30.10.2003, not previously published, come into consideration.

The compounds I, I a, I b and II described and their preparation are known per se. As the phosphorus-containing ligand, it is also possible to use mixtures containing at least two of the compounds I, I a, I b and II.

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 tritolyl phosphite, bidentate phosphorus-containing chelating ligands, and the phosphites of the formula I b

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.

The process step (a) of the process according to the invention is preferably carried out at an absolute pressure of 0.1 to 10 bar, more preferably 0.5 to 2 bar, in particular 0.8 to 1, 5 bar. The temperature in process step (a) is preferably 40 to 150 ^° C., particularly preferably 50 to 100 ^° C., in particular 60 to 70 ^° C.

The hydrocyanation in process step (a) is carried out in the presence of a promoter.

According to the present invention, the promoter used is preferably a Lewis acid. For the purposes of the present invention, a Lewis acid is understood as meaning a single Lewis acid, as well as a mixture of several, such as two, three or four Lewis acids.

Suitable Lewis acids are inorganic or organic metal compounds in which the cation is selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, boron, aluminum, Yttrium, zirconium, niobium, molybdenum, cadmium, rhenium and tin. Examples include ZnBr ₂ , ZnI ₂ , ZnCl ₂ , ZnSO ₄ , CuCl ₂ , CuCl, Cu (O ₃ SCF ₃ ) ₂ , CoCl ₂ , CoI ₂ , FeI ₂ , FeCl ₃ , FeCl ₂ , FeCl ₂ (THF) ₂ , TiCl ₄ (THF) ₂ , TiCl ₄ , TiCl ₃ , CITi (Oi-propyl) ₃ , MnCl ₂ , ScCl ₃ , AICI ₃ , (C ₈ H ₁₇ ) AICl ₂ , (C ₈ H ₁₇ ) ₂ AICI, (iC ₄ H ₉ ) ₂ AICI, (C ₆ Hs) ₂ AICI, (C ₆ H ₅ ) AICI ₂ , ReCl ₅ , ZrCl ₄ , NbCl ₅ , VCI ₃ , CrCl ₂ , MoCl ₅ , YCl ₃ , CdCl ₂ , LaCl ₃ , Er (O ₃ SCF ₃ ) ₃ , Yb (O ₂ CCF ₃ ) ₃ , SmCl ₃ , B (C ₆ H ₅ ) ₃ , TaCl ₅ , as described, for example, in US 6,127,567, US 6,171, 996 and US 6,380,421. Also contemplated are metal salts such as ZnCl ₂ , CoI ₂ and SnCl ₂ and organometallic compounds such as RAICl ₂ , R ₂ AICI, RSnO ₃ SCF ₃ and R ₃ B, where R is an alkyl or aryl group, such as for example, in US 3,496,217, US 3,496,218 and US 4,774,353.

Furthermore, according to US 3,773,809 as a promoter, a metal in cationic form selected from the group consisting of zinc, cadmium, beryllium, aluminum, gallium, indium, thallium, titanium, zirconium, hafnium, erbium, germanium, tin, vanadium, niobium, scandium , Chromium, molybdenum, tungsten, manganese, rhenium, palladium, thorium, iron and cobalt, preferably zinc, cadmium, titanium, tin, chromium, iron and cobalt, wherein the anionic portion of the compound may be selected from the group consisting halides, such as fluoride, chloride, bromide and iodide, anions of lower fatty acids containing from 2 to 7 carbon atoms, HPO ₃ ^{2 "} , H ₃ PO ^{2 "} , CF ₃ COO ^" , C ₇ H ₁₅ OSO ₂ ^" or SO ₄ ^2" . Furthermore, boron hydrides, organoborohydrides and boric acid esters of the formula R ₃ B and B (OR) ₃ , where R is selected from the group consisting of hydrogen, aryl radicals having between 6 and 18 carbon atoms, with alkyl, are suitable promoters from US Pat. No. 3,773,809 Groups with 1 to 7 carbon atoms substituted aryl radicals and with cyano-substituted alkyl groups having 1 to 7 carbon atoms substituted aryl radicals, preferably triphenylboron, called.

Furthermore, as described in US 4,874,884, synergistically effective combinations of Lewis acids can be used to increase the activity of the catalyst system. Suitable promoters may be selected, for example, from the group consisting of CdCl ₂ , FeCl ₂ , ZnCl ₂ , B (C ₆ H ₅ ) ₃ and (C ₆ Hs) ₃ SnX, where X is CF ₃ SO ₃ , CH ₃ C ₆ H ₄ SO ₃ or (C ₆ H ₅ ) ₃ BCN, wherein the ratio of promoter to nickel is a range of preferably from about 1:16 to about 50: 1.

For the purposes of the present invention, the term Lewis acid also encompasses the promoters mentioned in US Pat. Nos. 3,496,217, 3,496,218, 4,774,353, 4,874,884, 6,127,567, 6,171, 996 and 6,380,421.

Particularly preferred Lewis acids are among the metal salts mentioned, in particular metal halides, particularly preferably metal halides, such as fluorides, chlorides, bromides, iodides, in particular chlorides, of which in turn zinc chloride, iron (II) chloride and iron (III) chloride are particularly preferred.

The process step (a) can be carried out in any suitable device known to the person skilled in the art. For this purpose, customary devices are suitable for all reactions, as described, for example, in Kirk-Othmer, Encyclopedia of Chemical Technology, 4th ed. Vol. 20, John Wiley & Sons, New York 1996, pages 1040 to 1055. Examples are stirred tank reactors, loop reactors, gas recycle reactors, bubble column reactors or tubular reactors, each optionally with means for dissipating heat of reaction. The reaction can be carried out in several, such as two or three, devices. Also suitable, for example, reactors with backmixing characteristics.

In the hydrocyanation of process step (a), partial decomposition of the catalyst may occur. The resulting degradation products include, for example, components containing nickel (II) cyanide. As further degradation products arise, for example hydrolyzed phosphorus compounds which are derived by reaction of the respective substances used I, Ia, Ib or Il by traces of water, which may be contained in the starting materials, in particular in the hydrogen cyanide used, in the extractant or in the diluent. As further degradation products arise oxidized phosphorus compounds which are derived by reaction of the respective substances used I, Ia, Ib and Il to compounds with phosphorus atoms in the oxidation state (V) by reaction with elemental oxygen or by reaction with peroxides, which may be contained in the starting materials , in particular by leakage flows into the apparatus, in particular in apparatus operating at absolute pressures <1 bar, or by the dissolution of oxygen in pentenenitrile, for example during storage, with subsequent formation of peroxide compounds of the pentenenitriles. As further degradation products, in particular of the chelating ligands II used, monodentate degradation products which are derived by, for example, thermally induced or proton- or base-catalyzed rearrangement of the radicals on the phosphorus atoms of the respective structures and which have less hydrocyanation activity than the starting materials can be formed under unfavorable conditions.

The hydrocyanation in process step (a) is carried out in the presence of a diluent. For this purpose, as already stated, preferably hydrocarbons. This hydrocarbon preferably has at least one of the following properties according to the invention:

1.) The hydrocarbon must be chemically inert towards educts, products, catalyst components of the hydrocyanation and the extractant;

2.) The hydrocarbon must migrate into the extractant-rich phase during extraction;

3.) The hydrocarbon must have a vapor pressure, as a result of which it behaves as an intermediate in the distillation in step b) and in step d) without pentenenitrile. When pentenenitrile is used in step d), the diluent is a high boiler to pentenenitrile.

The diluent has a boiling point at atmospheric pressure of preferably 145 to 300 ⁰ C, more preferably between 150 and 250 ⁰ C, on.

As diluents, it is possible to use all organic compounds or mixtures of organic compounds which fulfill the abovementioned criteria. These are preferably selected from aliphatic or aromatic compounds or mixtures thereof.

The diluent in a preferred embodiment is at least one aliphatic linear or branched compound, at least one mononuclear or polynuclear aromatic compound optionally substituted with linear or branched alkyl groups, or a mixture thereof. Aliphatic compounds can be linear or branched compounds of 8 to 15 carbon atoms.

Aromatic compounds can be mononuclear or polynuclear compounds which are optionally substituted by linear or branched alkyl radicals. Preference is given to alkylbenzenes having C ₂ - to C ₃ o-, preferably C ₃ - to Ci ₅ radicals, which may moreover also carry functional groups selected from the ether or keto group, for example cumene. Mixtures of these aromatic compounds can be used.

Suitable compounds or mixtures of such compounds are e.g. available under the trade names Mihagol®, Marlotherm®, Therminol®, Thermogen®, Dowtherm®, or Diphenyl®. White oil is also a suitable diluent.

The diluent used is preferably anhydrous, wherein anhydrous means a water content of less than 100, preferably less than 50, in particular less than 10 ppm by weight. The hydrocarbon can be dried by suitable methods known to those skilled in the art, for example by adsorption or azeotropic distillation. The drying can take place in a step preceding the process according to the invention.

In the process according to the invention, a diluent is also understood as meaning a mixture of the individual diluents described above.

In process step (b), the hydrocyanation output is subjected to distillation to obtain a stream 1 containing the major part of the 3-pentenenitrile, and optionally a small amount of diluent, and a stream 2 as bottom product which contains the remainder of the 3-pentenenitrile, Adiponitrile, methylglutar- narditrile, ethylsuccinonitrile, the majority of the diluent, the hydrocyanation catalyst and the promoter.

The evaporation of process step (b) can be carried out in one stage or in several stages carried out in series at different temperatures and pressures. Furthermore, the evaporator stage of process step (b) can be carried out as a distillation column, wherein the operation as a gain or stripping column or as a column with abrasion and reinforcing member is possible. In one embodiment, the evaporator stage (b) is operated as a distillation column in the driven mode.

If the difference between the boiling point of the 3-pentenitrile and the boiling point of the diluent is more than 80 K, the evaporation stage will preferably be carried out in one stage. Is the difference between the boiling point of the 3-pentenitrile and the boiling point of the diluent less than 80 K, the evaporation stage is preferably carried out in multiple stages.

In a further embodiment of the method according to the invention, at least one of the single-stage evaporator stages of process step (b) is operated with a divided bottom, the liquid flowing from a first bottom of the relevant evaporator stage to the evaporator, which is generally large in relation to the bottom draw stream However, flow stream from the evaporator does not return directly into the sump, but in a second sump, which is separated from the first sump, receives, receives from the second sump the bottom draw stream and the remaining excess from the evaporator recycle stream overflows into the first sump, where as the bottom draw stream from the second sump, a mixture is obtained which is depleted of low-boiling components compared with the withdrawal from the first sump.

The absolute pressure in process step (b) is preferably 0.001 to 1 bar, more preferably 0.005 to 0.15 bar. The distillation is carried out so that the temperature in the bottom of the distillation apparatus is preferably 40 to 180 ^° C., particularly preferably 50 to 140 ^° C., in particular 60 to 120 ^° C. The distillation is implemented in a way that the temperature at the top of the distillation apparatus is preferably from -15 to 150 ⁰ C, particularly preferably 0 to 100 ⁰ C, in particular 10 to 80 ⁰ C, is. In a particularly preferred embodiment of the method according to the invention, the abovementioned temperature ranges are observed both at the top and in the bottom.

An essential separation of the pentenenitriles before the subsequent extraction in process step (c) is advantageous, since otherwise phase separation in the extraction may be difficult or prevented, and the efficiency of extraction of catalyst components from the hydrocyanation by a high pentenenitrile pentane concentration is adversely affected ,

The remainder of 3-pentenenitrile in stream 2 after process step b) is so low that a phase separation in the extraction is made possible. The content of 3-pentenenitrile after the distillation is preferably <30% by weight, particularly preferably <25% by weight, very particularly preferably <20% by weight.

In a preferred embodiment of the process according to the invention, the stream 1 obtained in process step (b) is recycled wholly or partly, if appropriate after workup by distillation, in process step (a).

In process step (c), the stream 2 is extracted with an extractant to obtain a stream 3 which comprises the major part of the dilution and a stream 4 containing most of the adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the promoter and 3-pentenenitrile radicals.

In a preferred embodiment, a non-polar aprotic liquid F is added to the stream 2 in step c), thereby obtaining the stream 2 ^* . In this case, liquid means that the compound F is present in liquid form at least under the pressure and temperature conditions prevailing in step a); under other pressure and temperature conditions F can also be solid or gaseous.

Suitable non-polar (or apolar) aprotic liquid F are all compounds which are liquid under the conditions of step a) and which do not chemically or physically support the catalyst, eg the Ni (O) complex with phosphorus-containing ligands and / or the free phosphorus-containing ligands or do not change significantly. Compounds suitable as liquid F do not contain any ionizable proton in the molecule and generally have low relative dielectric constants (ε _r <15) or low electrical dipole moments (μ <2.5 Debye).

Suitable F are, in particular, hydrocarbons which may be, for example, unhalogenated or halogenated, and, in particular, tertiary amines and carbon disulfide.

In another embodiment, the liquid F is a hydrocarbon K ^* . Suitable are aliphatic, cycloaliphatic or aromatic hydrocarbons K ^* . Suitable aliphatic hydrocarbons K ^* are, for example, linear or branched alkanes or alkenes having 5 to 30, preferably 5 to 16, carbon atoms, in particular pentane, hexane, heptane, octane, nonane, decane, undecane and dodecane, in each case all isomers.

Suitable cycloaliphatic hydrocarbons have, for example, 5 to 10 C atoms, such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane and

Cyclodecane. Also substituted, especially d-io-alkyl-substituted cycloaliphatic such as methylcyclohexane are suitable. As aromatic hydrocarbons are preferably those having 6 to 20 carbon atoms, in particular benzene, toluene, o-, m- and p-xylene, naphthalene and anthracene. It is also possible to use substituted, preferably C _MO -alkyl-substituted aromatics such as ethylbenzene.

The hydrocarbon K ^* is particularly preferably selected from the compounds mentioned below for the hydrocarbon K. The hydrocarbon K ^* is very particularly preferably identical to the hydrocarbon K, ie the same hydrocarbon is used for the extraction and as liquid F. Embodiment of adding the liquid

The non-polar aprotic liquid F can be added to stream 2 in conventional mixing devices. Preferably, because it is particularly simple in terms of process engineering, in step c) the nonpolar aprotic liquid F is mixed with the reaction output in a stirred tank or a pumped circulation.

Preferably, the nonpolar aprotic liquid is intimately mixed with the stream 2. Suitable stirred vessels are customary liquid mixers which can be provided with intensive mixing mixing elements and / or static or movable internals.

The use of a pumped circulation is also preferred. It is usually operated such that the ratio of Umpumpmenge to ejection from the Umpumpkreis, 0.1: 1 to 1000: 1, preferably 1: 1 to 100: 1 and more preferably 2: 1 to 25: 1. As circulation pump are suitable, e.g. Gear pumps or other common pumps. Preferably, the circulation pump operates against an overflow which, at a defined pressure of e.g. 3 to 10 bar (abs.) Opens.

In a further preferred embodiment, the liquid F is a partial stream of stream 2 (catalyst-enriched hydrocarbon K, see below) obtained in step b). This means that in step b) a part of stream 2 is branched off and the branched-off part is added again to stream 2 in step b). Accordingly, in this embodiment, a part of the stream 2 is circulated.

In another, likewise preferred embodiment, the non-polar aprotic liquid F is metered directly into a residence time zone (see below), for example at the beginning thereof.

The addition of the liquid F is usually carried out at temperatures of 0 to 150, preferably 10 to 100 and in particular 20 to 80 ⁰ C, and pressures of 0.01 to 100, preferably 0.1 to 10 and in particular 0.5 to 5 bar (abs.).

The required amount of liquid F can vary within wide limits. It is usually less than the amount of hydrocarbon K used, with which is extracted in step b), but may also be larger. The amount of liquid F is preferably 0.1 to 200% by volume, in particular 1 to 50% by volume and more preferably 5 to 30% by volume, based on the amount of hydrocarbon K used for the extraction in step b) , Particularly preferred is the addition of the liquid F in an amount which is sufficient to achieve phase separation in the stream 2 ^* prior to feeding into the extraction (step c). In this embodiment, the biphasic stream 2 ^* after step b) and before step c) is passed through a residence time path (see below). The residence time section acts as a decanter and separates the two phases of the current 2 ^* from each other. The separated first phase contains the major part of the contents of the - possibly narrowed - effluent, and portions of the catalyst to be extracted, and is fed into the extraction apparatus. The separated second phase, which is obtained in addition to the first phase, is also - usually elsewhere - fed together with the hydrocarbon K (extractant) in the extraction apparatus. Preferably, a countercurrent of the phases is brought about. Thus, in this embodiment, stream 2 ^{* is} supplied as two separate phases of extraction.

Process (c) may be carried out in any suitable apparatus known to those skilled in the art. The extraction of process step (c) preferably takes place in countercurrent extraction columns, mixer-settler cascades or combinations of column-type mixer-settler cascades. Particularly preferred is the use of countercurrent extraction columns, which are particularly equipped with sheet metal packages as dispersing elements.

In a further particularly preferred embodiment, the countercurrent extraction is carried out in a compartmented, stirred extraction column.

In a preferred embodiment, the extractant is used as the continuous phase, the bottoms discharge obtained in process step (b) is used as the disperse phase.

In the extraction, a phase ratio of 0.1 to 10, calculated as the ratio of the volume of the extractant supplied to the volume of the mixture to be extracted, can be used. In a preferred embodiment, the extraction is operated at a phase ratio of 0.4 to 3.5, in a particularly preferred embodiment at 0.75 to 3.5.

The absolute pressure in process step (c) is preferably 0.1 to 10 bar, particularly preferably 0.5 to 5 bar, in particular 0.9 to 2.5 bar. The extraction is preferably carried out at temperatures of -15 to 120 ^° C., more preferably 0 to 60 ^° C., in particular 25 to 45 ^° C.

The extractant is preferably a hydrocarbon K having 6 to 14 carbon atoms, more preferably 6 to 1 1 carbon atoms. It preferably has a boiling point of at least 30 ^° C., more preferably at least 60 ^° C., in particular at least 90 ^° C., and preferably at most 140 ^° C., particularly preferably at most 135 ^° C., in particular at most 130 ^° C., in each case at a pressure of 10 ⁵ Pa absolute.

Particularly preferred may be a hydrocarbon, which in the context of the present invention, a single hydrocarbon, as well as a mixture of such hydrocarbons, for the separation, in particular by extraction, of adiponitrile from a mixture containing adiponitrile and the (eg Ni (O) containing ) Catalyst, wherein the hydrocarbon has a boiling point in the range between 90 ⁰ C and 140 ⁰ C and preferably dissolves the Ni (0) catalyst. From the mixture obtained after the separation according to this process, the catalyst can be advantageously obtained by distillative removal of the hydrocarbon, if appropriate with addition of a suitable solvent which has a higher boiling point than the hydrocarbon (eg pentenenitrile). In this case, the use of a hydrocarbon having a boiling point in the said range allows a particularly economical and technically simple separation, since it is possible to condense the distilled-off hydrocarbon with river water.

Suitable hydrocarbons are described, for example, in US Pat. No. 3,773,809, column 3, lines 50-62. Preferably, a hydrocarbon selected from cyclohexane, methylcyclohexane, cycloheptane, n-hexane, n-heptane, isomeric heptanes, n-octane, iso-octane, isomeric octanes such as 2,2,4-trimethylpentane, cis- and trans- Decalin or mixtures thereof, in particular from cyclohexane, methylcyclohexane, n-heptane, isomeric heptanes, n-octane, isomeric octanes such as 2,2,4-trimethylpentane, or mixtures thereof, into consideration. Cyclohexane, methylcyclohexane, n-heptane or n-octane are particularly preferably used.

The hydrocarbon K used as extractant is preferably anhydrous, wherein anhydrous means a water content of less than 100, preferably less than 50, in particular less than 10 ppm by weight. The hydrocarbon may be dried by suitable methods known to those skilled in the art, for example by adsorption or azeotropic distillation. The drying can take place in a step preceding the process according to the invention.

In the process according to the invention, an extraction agent is also understood to mean a mixture of the individual extraction agents described above.

According to the invention, the diluent is selected from the group referred to in process step (a). The extractant is selected from the above The liquid F is selected from the above-mentioned group K or from the group K ^* . The diluent used in step a) is not equal to the extractant used from the group K or the liquid F, which is selected from the group K or K ^* .

In a preferred embodiment of the process according to the invention, the reaction effluent of the hydrocyanation during or after step a) or stream 2 during or after step b) is treated with ammonia or a primary, secondary or tertiary aromatic or aliphatic amine. Aromatic includes alkylaromatic, and aliphatic includes cycloaliphatic.

It has been found that the content of catalyst, in particular of nickel (0) complex or ligand, in the extraction (step c)) in the second phase enriched with dinitriles (stream 4) is reduced by this ammonia or amine treatment lets, ie During extraction, the distribution of the Ni (0) complex or ligands is shifted to the two phases in favor of the first phase. The Ammoniakbzw. Amine treatment improves catalyst enrichment in stream 3; this means lower catalyst losses in the catalyst circulation and improves the economics of Hydrocyanierung.

Accordingly, in this embodiment the extraction is preceded by a treatment of the reaction effluent or of stream 2 with ammonia or an amine or takes place during the extraction. The treatment during the extraction is less preferred.

It is particularly preferable to add the ammonia or the amine together with the non-polar aprotic liquid F. In particular, the addition of the liquid F and of the ammonia or amine takes place in the same mixing device.

The amines used are monoamines, diamines, triamines or higher-functional amines (polyamines). The monoamines usually have alkyl radicals, aryl radicals or arylalkyl radicals having 1 to 30 C atoms; suitable monoamines are, for example, primary amines, for example monoalkylamines, secondary or tertiary amines, for example dialkylamines. Suitable primary monoamines are, for example, butylamine, cyclohexylamine, 2-methylcyclohexylamine, 3-methylcyclohexylamine, 4-methylcyclohexylamine, benzylamine, aniline and derivatives of aniline, tetrahydrofurfurylamine and furfurylamine mono- or polysubstituted with alkyl groups, aryl groups and / or non-protic functional groups. minute Examples of suitable secondary monoamines are diethylamine, dibutylamine, di-n-propylamine and N-methylbenzylamine. Suitable tertiary amines are, for example, trialkylamines having C 1-10 -alkyl radicals, such as trimethylamine, triethylamine or tributylamine. Ammonia, aniline or derivatives of aniline mono- or polysubstituted with alkyl groups, aryl groups and / or non-protic functional groups are preferably used.

Suitable diamines are, for example, those of the formula R ¹ -NH-R ² -NH-R ³ , where R ¹ , R ² and R ³ independently of one another are hydrogen or an alkyl radical, aryl radical or arylalkyl radical having 1 to 20 C atoms. The alkyl radical can also be cyclic, in particular linearly or in particular for R ² . Suitable diamines are, for example, ethylenediamine, the propylenediamines (1,2-diaminopropane and 1,3-diaminopropane), N-methylethylenediamine, piperazine, tetramethylenediamine (1,4-diaminobutane), N, N'-dimethylethylenediamine, N- Ethylethylenediamine, 1,5-diaminopentane, 1,3-diamino-2,2-diethylpropane, 1,3-bis (methylamino) propane, hexamethylenediamine (1,6-diaminohexane), 1, 5-diamino-2-methylpentane, 3- (Propylamino) -propylamine, N, N'-bis (3-aminopropyl) -piperazine, N, N'-bis (3-aminopropyl) -piperazine and isophoronediamine (IPDA).

Suitable triamines, tetramines or higher-functional amines are e.g. Tris (2-aminoethyl) amine, tris (2-aminopropyl) amine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), isopropyltriamine, dipropylenetriamine and N, N'-bis (3-aminopropyl- ethylenediamine). Aminobenzylamines and aminohydrazides having 2 or more amino groups are also suitable.

Naturally one can also use mixtures of ammonia with one or more amines, or mixtures of several amines.

The molar ratio of amine to ammonia can be varied within wide limits, is usually at 10000: 1 to 1: 10000.

Preference is given to using ammonia or aliphatic amines, in particular triallamins having 1 to 10 C atoms in the alkyl radical, e.g. Trimethylamine, triethylamine or tributylamine, and diamines such as ethylenediamine, hexamethylenediamine or 1, 5-diamino-2-methylpentane.

Particularly preferred is ammonia alone, i. It is particularly preferable to use no amine in addition to ammonia. Anhydrous ammonia is most preferred; Anhydrous means a water content below 1 wt .-%, preferably below 1000 ppm and in particular below 100 ppm by weight.

The amount of ammonia or amine used depends inter alia on the type and amount of the catalyst, for example the nickel (0) catalyst and / or the ligands, and - if used - on the type and amount of Lewis acid, in the hydrocyanine - tion is used as a promoter. The molar ratio of ammonia or amine function to Lewis acid is usually at least 1: 1. The upper limit of this molar ratio is generally not critical and is for example 100: 1; However, the excess of ammonia or amine should not be so great that the Ni (0) complex or its ligands decompose. The molar ratio of ammonia or amine function to Lewis acid is preferably 1: 1 to 10: 1, more preferably 1: 5: 1 to 5: 1, and in particular about 4.0: 1, if a mixture of ammonia and amine is used , These molar ratios apply to the sum of ammonia and amine functions.

The temperature in the treatment with ammonia or amine is usually not critical and is for example 10 to 140, preferably 20 to 100 and in particular 20 to 90 ⁰ C. The pressure is usually not critical.

The ammonia or the amine can be added to the reaction effluent in gaseous form, liquid (under pressure) or dissolved in a solvent. Suitable solvents are e.g. Nitriles, in particular those which are present in the hydrocyanation, and furthermore aliphatic, cycloaliphatic or aromatic hydrocarbons, as used in the inventive method as an extractant, for example, cyclohexane, methylcyclohexane, n-heptane or n-octane.

The ammonia or amine addition is carried out in conventional devices, for example those for gas introduction or in liquid mixers. The precipitated in many cases solid can either remain in the reaction, ie. The extraction is fed to a suspension or separated by sedimentation (cross-flow filtration), centrifuging (centrifugal separator), filters or through a belt chamber, possibly rinsed, or as described in d).

In a particular embodiment of the process according to the invention, the following process step (d) is additionally carried out after process step (c): d) distillation of the stream 3 to obtain a stream 5 as top product which contains the predominant part of the extractant and a stream 6 containing the at least one hydrocyanation catalyst and most of the diluent.

Step d) of the method according to the invention is explained in more detail by FIG. 2, the reference symbols 6 and 9 to 11 having the following meanings: 6 stream 3, containing the major part of the diluent, the

Hydrocyanierungskatalysators and the extractant, see also Figure 1 9 step d)

Stream 5, containing the major part of the extractant 1 1 stream 6, containing the hydrocyanation catalyst and the major part of the diluent

The process step (d) can be carried out in any suitable apparatus known to the person skilled in the art. The distillation of process step (d) preferably takes place in one or more evaporation stages and distillation columns.

As internals for the distillation columns are preferably structured sheet metal packing, structured fabric packing, bubble trays, dual-flow trays or beds of packing or combinations of two or more of these classes of separating internals used. The distillation column of process step (d) may be carried out with one or more liquid or gaseous side draws. The distillation column from process step (d) can be carried out as a dividing wall column with one or more existing gaseous or liquid side draws.

The one or more evaporator stages or the distillation column of process step (d) may in particular be equipped with falling film evaporators, thin film evaporators, natural circulation evaporators, forced circulation flash evaporators and multiphase spiral tube evaporators.

In a further embodiment of the method according to the invention, at least one of the evaporator units of process step (d) is operated with a divided bottom, wherein the circulating stream, which is generally large relative to the bottom draw stream, is passed from a first bottom of the relevant evaporator stage to the evaporator However, evaporator does not return directly into the sump, but in a second sump, which is separated from the first sump, receives, receives from the second sump the bottom draw stream and the remaining excess from the evaporator recirculation flow into the first sump overflow, being used as bottom draw stream from the second Swamp will receive a mixture that is compared to the deduction from the first swamp of low-boiling enriched.

The absolute pressure in process step (d) is preferably 0.001 to 2.0 bar, more preferably 0.01 to 0.5 bar. The distillation is conducted so that the temperature in the bottom of the distillation apparatus is preferably 40 to 150 ⁰ C, particularly preferably 70 to 120 ⁰ C, in particular 80 to 100 ⁰ C, is. The distillation is carried out so that the temperature at the top of the distillation apparatus preferably -15 to 100 ⁰ C, more preferably 0 to 60 ⁰ C, in particular 20 to 50 ⁰ C, is. In a particularly preferred embodiment of the method according to the invention, the abovementioned temperature ranges are observed both at the top and in the bottom.

In the separation of the extractant to recover the catalyst according to process step d), in a preferred embodiment of the present invention, a diluent is added as an intermediate for distillation. This solvent change has, on the one hand, the advantage that effective depletion of the extractant from the high-boiling catalyst stream is possible at evaporator temperatures which are low enough not to damage the particular nickel catalyst used, and in particular the chelate ligands, while the pressure is still high enough in order to condense the comparable compared to the catalyst components tively low-boiling extraction agent at the head of the evaporator stage or distillation column even with conventional cooling water temperatures of 25 to 50 ⁰ C. The solvent change also has the advantage that the flowability and the single-phase of the catalyst solution is ensured since, depending on the temperature and residual content of extractant - without the addition of the diluent - possibly catalyst components can crystallize. In this case, the diluent, which is difficult or impossible to completely separate, for example, from the extractants cyclohexane or methylcyclohexane, depending on the pressure conditions or due to Mindestsdampfdruckazebildung at a proportion of preferably up to 10 wt .-%, particularly preferably up to 5 wt .-%, ins - Particular to 1 wt .-%, based on the total amount of Extractmittelzulauf- stream to the extraction column in process step (c), not disturbing to the inventive method.

The stream 5 obtained in process step (d), comprising most of the extractant, is at least partly recycled to the extraction step (c) in a preferred embodiment of the process according to the invention. The recycled stream 5 is preferably dried before the extraction step (c), so that the water content in this stream is preferably less than 100 ppm, more preferably less than 50 ppm, in particular less than 10 ppm.

The stream 6 obtained in process step (d), comprising the catalyst, is recycled in a further preferred embodiment of the process according to the invention at least partially into the hydrocyanation of process step (a). In a preferred embodiment of the process according to the invention, the proportion of extractant in stream 6 is preferably less than 10% by weight, especially preferably less than 5% by weight, in particular less than 1% by weight, based on the total amount of stream 6.

Since the separation of the extractant from the catalyst is thus not necessarily quantitative, it may be found that extractant still contained in stream 6 is also recycled to the hydrocyanation stage. This extractant is then in the subsequent process step (b) described above substantially in the stream 1, containing pentenenitriles, transferred, and may possibly level up there if it is not separated, for. by distillation before recycling.

In a further embodiment of the process according to the invention, stream 1, which is obtained in process step (b), is recycled in process step (a), in whole or in part, if appropriate after working up by distillation.

In a further embodiment of the process according to the invention, the diluent is used as feed to the distillation column in the distillation in step d). The pentenenitrile boils at a higher temperature than the extractant and thus passes predominantly into the bottom, thereby optionally the temperature in the distillation bottoms can be limited in order to protect the hydrocyanation catalyst thermally.

In a further embodiment of the process according to the invention, the stream 5 obtained in process step (d) is completely or partially, preferably> 90% by weight, more preferably> 95% by weight, in particular> 99% by weight in process step ( c) returned.

In a further embodiment of the process according to the invention, the stream 6 obtained in process step (d) is optionally recycled to process step (a) after regeneration, if appropriate also in the presence of the diluent.

Regeneration in the sense of the present process is understood to mean a reductive treatment of the product stream obtained in process step (d), as described, for example, in DE 103 51 002 A1.

As a result, the free ligand contained in the product stream is thus converted again into a nickel (0) complex by the process according to the invention. 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.

When 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. Particularly preferred are iron and zinc. When aluminum is used as the reducing agent it is advantageous to pre-activate it by reaction with a catalytic amount of mercury (II) salt or metal alkyl. For the preactivation, triethylaluminum is preferably used 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, more preferably less than 20 mesh.

In the method of the present invention, when the reducing agent used is a metal which is more electropositive than nickel, 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, these are preferably lithium alkyls, sodium alkyls, magnesium alkyls, in particular Grignard reagents, zinc alkyls or aluminum alkyls. Particular preference is given to aluminum alkyls, such as trimethylaluminum, triethylaluminum, triisopropylaluminum or mixtures thereof, in particular triethylaluminum. The metal alkyls can be used in bulk or dissolved in an inert organic solvent, such as hexane, heptane or toluene.

When complex hydrides are used as the reducing agent in the process of the present invention, it is preferable to use 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, more preferably 1: 1 to 1:50, in particular 1: 1 to 1: 5.

The hydrocarbon used as diluent according to the invention behaves in the two distillations b) and d) of the process according to the invention, on the one hand the separation of 3-pentenenitrile after the hydrocyanation and on the other hand the optional separation of the extractant after extraction, although he both cases with the catalyst is removed via the bottom, as intermediate boiler, whereby the temperatures are limited in the column bottom and thermal degradation of the catalyst is avoided.

The essential advantages of the method according to the invention are thus that due to the complete separation of 3-pentenenitrile from the reaction mixture before the extractive workup in the extraction, the phase ratio and the distribution coefficient are positively changed and this by the presence of the intermediate boiler "diluent" temperature-friendly and without This makes it possible to use smaller and more favorable equipment for extraction and requires less extractant so that less vapor is evaporated and condensed during later distillation, thus saving energy of 3-pentenenitrile is made possible by adding to the reaction mixture a hydrocarbon having the above-mentioned properties.

The present invention also relates to the use of diluents in a process for the preparation of adiponitrile-containing mixtures for lowering the bottom temperature in the purification of the product, to reduce the thermal degradation of the catalyst and to prevent the crystallization of the catalyst during the process.

The present invention will be explained in more detail with reference to the following examples

Examples

Example 1 :

In a 500 ml flask with stirrer under argon 195.05 g (4 wt .-% in pentenenitrile, 0.06 mol) of NiC ^ suspension in white oil (163 g), with chelate solution (70 g, 65 % in white oil) and heated to 75 ⁰ C. Then zinc powder (4.2 g, 0.064 mol) is added and stirred at 75 ⁰ C for 4 h. After cooling to room temperature, the batch is biphasic. The upper phase has a Ni (0) value of 0 wt .-%, the lower phase has a Ni (0) value of 1, 2 wt .-% to.

187 g of adiponitrile are added to the reaction mixture and 15 min. touched. After phase separation, the upper phase has a Ni (0) value of 0 wt .-%, the lower phase has a Ni (0) value of 0.6 wt .-%. The resulting 3-pentenenitrile is to a residual content of about 10 removed on a rotary evaporator at 95 ⁰ C and 30 mbar wt .-%. The reaction mixture continues to remain liquid in two phases. to like. The upper phase has a Ni (0) value of 0 wt .-%, the lower phase has a Ni (0) value of 0.8 wt .-%.

Example 2:

195.0 g (4% by weight in pentenenitrile, 0.06 mol) of NiCl suspension in Mihagol® (163 g) are suspended under argon in a 500 ml flask with stirrer, with chelate solution (70 g, 65% in white oil) and heated to 75 ⁰ C. Then zinc powder (4.2 g, 0.064 mol) is added and stirred at 75 ⁰ C for 4 h. After cooling to room temperature, the batch is biphasic. The upper phase has a Ni (0) value of 0.2 wt .-%, the lower phase to a Ni (0) value of 1, 0 wt .-% to.

187 g of adiponitrile are added to the reaction mixture and 15 min. touched. After phase separation, the upper phase has a Ni (0) value of 0 wt .-%, the lower phase has a Ni (0) value of 0.75 wt .-%. The resulting 3-pentenenitrile is to a residual content of about 10 removed on a rotary evaporator at 95 ⁰ C and 30 mbar wt .-%. The reaction mixture remains two-phase liquid homogeneous. The upper phase has a Ni (0) value of 0 wt .-%, the lower phase has a Ni (O) value of 1, 1 wt .-% on.

Examples 1 and 2 use a chelate ligand of the following formula according to DE 103 51 002 A1:

The determination of the Ni (0) content is carried out according to the method disclosed in DE 10351000 A1. For this purpose, the solutions with tri (m / p-tolyl) phosphite (phosphite typically 1 g per 1 g solution) are added and 30 min at 80 ⁰ C maintained in order to achieve a complete recomplexing. Subsequently, for electrochemical oxidation in a cyclovoltametric measuring apparatus, the current-voltage curve in ru measured solution against a reference electrode, which determines the concentration corresponding peak current and a calibration with solutions of known Ni (0) concentration of the Ni (O) content of the test solution - corrected by the subsequent dilution with tri (m / p-tolyl) phosphite - determined. The stated Ni (0) values indicate the content of Ni (O) in% by weight, based on the total reaction solution, determined by this method.

Claims

claims

1. A process for the preparation of adiponitrile-containing mixtures, which is characterized by the present process steps:

a) reacting 3-pentenenitrile with hydrogen cyanide in the presence of a hydrocyanation catalyst, a promoter and a diluent to obtain a hydrocyanation output comprising 3-pentenenitrile, adiponitrile, methylglutaronitrile, ethylsuccinonitrile, the diluent, the hydrocyanation catalyst, the promoter and optionally decomposition products of the catalyst; b) distilling the hydrocyanation effluent from step a) to obtain a stream 1 overhead product containing 3-pentenenitrile and a stream 2 bottoms product containing adiponitrile, methylglutaronitrile, ethylsuccinonitrile, most of the diluent, hydrocyanation catalyst and promoter; c) extraction of the stream 2 with an extractant to obtain a stream 3 containing the major part of the diluent, the hydrocyanation catalyst and the extractant, and a stream 4 containing the major part of the adiponitrile, methylglutardinitrile, ethylsuccinonitrile and the promoter ,

2. The method according to claim 1, characterized in that subsequent to method step (c) additionally the following method step (d) is carried out:

d) distilling the stream 3 to obtain a stream 5 as top product containing the major part of the extractant, and a stream 6 containing the at least one hydrocyanation catalyst and the major part of the diluent.

3. The method according to claim 1 or 2, characterized in that the reaction onsaustrag the hydrocyanation during or after step a) or the stream 2 during or after step b) treated with ammonia or a primary, secondary or tertiary aromatic or aliphatic amine becomes.

4. The method according to claim 2 or 3, characterized in that the stream 6 obtained in process step (d) is at least partially recycled to the hydrocyanation of process step (a). όό

5. The method according to any one of claims 1 to 4, characterized in that the diluent has a boiling point at atmospheric pressure of 145 to 300 ⁰ C.

6. The method according to any one of claims 1 to 5, characterized in that the diluent is at least one aliphatic linear or branched compound or at least one mononuclear or polynuclear aromatic compound which is optionally substituted with linear or branched alkyl radicals, or a mixture thereof is.

7. The method according to any one of claims 1 to 6, characterized in that in step c) the stream 2, a non-polar aprotic liquid F is added.

8. The method according to any one of claims 1 to 7, characterized in that a hydrocarbon K having 6 to 14 carbon atoms is used as the extraction agent.

9. The method according to any one of claims 1 to 8, characterized in that a mixture of isomeric pentenenitriles is used as 3-pentenenitrile.

10. The method according to any one of claims 1 to 9, characterized in that the stream 1 obtained in process step (b) wholly or partly, optionally after work-up by distillation in process step (a) is recycled.

1 1. The method according to any one of claims 2 to 10, characterized in that the stream 5 obtained in step (d) is at least partially recycled to the extraction step (c).

12. The method according to any one of claims 1 to 1 1, characterized in that the 3-pentenenitrile used is derived from a homogeneous hydrocyanation of 1, 3-butadiene.

13. Use of diluents in a process for the preparation of adiponitrile-containing mixtures for lowering the bottom temperature in the

Purification of the product, to reduce the thermal degradation of the catalyst and to avoid the crystallization of the catalyst during the process.

14. Use according to claim 13, characterized in that the diluent has a boiling point at atmospheric pressure of 145 to 300 ⁰ C.