MXPA06007883A - Method for producing 3-pentenenitrile - Google Patents

Abstract

The invention relates to a method for producing 3-pentenenitrile, said method being characterised by the following steps:(a) 1,3-butadiene is reacted with hydrogen cyanide on at least one catalyst to obtain a flow (1) containing 3-pentenenitrile, 2-methyl-3-butenenitrile, the at least one catalyst, and 1,3-butadiene;(b) the flow (1) is distilled in a column to obtain a top product flow (2) rich in 1,3-butadiene, and a bottom product flow (3) that is poor in 1,3-butadiene and contains 3-pentenenitrile, the at least one catalyst, and 2-methyl-3-butenenitrile;(c) the flow (3) is distilled in a column to obtain a top product flow (4) containing 1,3-butadiene, a flow (5) in a side-tap of the column, containing 3-pentenenitrile and 2-methyl-3-butenenitrile, and a bottom product flow (6) containing the at least one catalyst;and (d) the flow (5) is distilled to obtain a top product flow (7) containing 2-methyl-3-butenenitrile, and a bottom product flow (8) containing 3-pentenenitrile.

Description

KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, PL, PT, RO, SE, SI, SK, TR), OAPI (BF, BJ, CF, CG , Cl, MG, MK, MN, MW, MX, MZ, NA, NI, NO, NZ, OM, PG, CM, GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG). PH, PL, PT, RO, RU, SC, SD, SE, SG, SK, SL, SY, TJ, TM, 'TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, YU , ZA, ZM, Verdffenüicht: ZW. - - • mit intemationalem Recherchenbericht - vor Ablauf der für Anderungen der Ansprüche geltenden Frist; Veroffentlichung wird wiederholt, falls Anderungen (84) Bestimmungsstaaten (soweit nicht anders angegeben, ßr eintreffen jede verfügbare regionale Schutzrechtsart): ARJPO (BW, GH, GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, Zur Erkliirung der Zweibuchstaben -Codes und der anderen Ab- ZM, ZW), eurasisches (AM, AZ, BY, KG, KZ, MD, RU, kurzungen wird auf die Erklárungen ("Guidance Notes on CoTJ, TM), europaisches (AT, BE, BG , CH, CY, CZ, DE, DK, des and Abbreviations ") am Anfangjeder regularen Ausgabe der EE, ES, Fl, FR, GB, GR, HU, TE, IS, IT, LT, LU, MC, NL, PCT- Gazette verwiesen.

PROCEDURE FOR PREPARING 3-PENTENONITRILO Description The present invention relates to a process for the preparation of 3-pentenenitrile.

Adiponitrile is an important starting product in the manufacture of nylon, which is obtained by double hydrocyanation of 1,3-butadiene. In this process, in a first hydrocyanation 1,3-butadiene is hydrogenated to convert it to 3-pentenenitrile, obtaining as by-products mainly 2-methyl-3-butenonitrile, 4-pentenenitrile, 2-pentenenitriles, 2-methyl- 2-butenonitriles, C9 nitriles and methylglutaronitrile. In a second hydrocyanation, following the first one, 3-pentenenitrile is transformed by hydrocyanic acid into adiponitrile. Both hydrocyanates are catalyzed by nickel (0) -phosphorus complexes.

For the second hydrocyanation it is essential that the 3-pentenenitrile used be free of 2-methyl-3-butenonitrile, because otherwise the 2-methyl-3-butenonitrile would be cross-linked to become the unwanted by-product methylglutaronitrile.

An overview of olefin catalyzed hydrocyanation by nickel is described in Tolman et al., Adv. Cat. 33, 1-46 (1985).

The hydrolyzation of 1,3-butadiene by the use of a nickel catalyst of the formula Ni [P (OR) 3] 4 is described in US 3,496,215. The disadvantage of this method is that no suitable technique is indicated to fully recover 1,3-butadiene or the catalyst.

US Pat. No. 5,693,843, US Pat. No. 5,696,280, US Pat. No. 5,821,378 and US Pat. No. 5,981,772 disclose 1,3-butadiene hydrocyanates with phosphorus-containing multidentate ligands, although in the various embodiments, no suitable method is disclosed for recover the components of the catalysts.

US 4,810,815 discloses how hydrocyanation is carried out in one or more reactors and how to establish connection between them, mentioning the possibility of continuous exploitation of agitation vessels or cascades of agitation vessels, although in the examples only one mode of semi-continuous process is described in detail, by which the specialist can not directly deduce under what conditions the continuous process mode has to be performed in agitator vessels.

US Pat. No. 3,7-73,809 describes a process for separating organic phosphorus compounds and their metal complexes from organic nitriles in the hydrocyanation of olefins. The separation is effected there by contacting the product with a cyclic paraffin or a parafinoid hydrocarbon. In this way, a multiphase liquid system is formed. This method of separation and recovery of catalyst components by extraction is not applicable in the hydrocyanation of 1,3-butadiene, due to the too low concentration of dinitriles in the product of the reaction.

Accordingly, the object of the present invention is to provide an integrated process for the preparation of 3-pentenonitrile by hydrocyanation of 1,3-butadiene, wherein the 3-pentenenitrile is substantially free of 2-methyl-3-. butenonitrile, the 1,3-butadiene applied is preferably returned in order to increase the yield of the process, and the catalyst is preferably separated from the pentenenitriles and returned for the purpose of economic application.

It is known that 2-methyl-3-butenonitrile reacts under hydrocyanation conditions to become methylglutanedonitrile, in particular in the presence of nickel (0) complexes. Therefore, another object of the present invention is to provide a process for the preparation of 3-pentenenitrile by hydrocyanation of 1,3-butadiene, in which preferably it is returned to hydrocyanation as little as possible of 2-methyl-3-. butenonitrile. For this reason, in the process according to the invention, the recycled stream of the catalyst and the returned part of the 1,3-butadiene have to be liberated as much as possible from 2-methyl-3-butenonitrile.

For the rest, the catalysts for homogeneously dissolved hydrocyanation are, as is known, labile in the thermal order. Therefore, another object of the present invention is to provide a process for the preparation of 3-pentenenitrile by the hydrocyanation of 1,3-butadiene, in which the catalyst is preferably subjected to a thermal load as low as possible.

According to the invention, this object is achieved by a process for the preparation of 3-pentenenitrile.

The process according to the invention is characterized by the following steps: (a) Transformation of 1,3-butadiene with hydrocyanic acid with at least one catalyst, obtaining a stream 1 containing 3-pentenenitrile, 2-methyl-3-butenenitrile, the catalyst, which is at least one, and , 3-butadiene, (b) distillation of stream 1 in a column, obtaining, as a superior product, a stream 2 rich in 1,3-butadiene and, as the discharge product, a stream 3 poor in 1,3-butadiene, containing 3 - pentenenitrile, the catalyst, which is at least one, and 2-methyl-3-butenenitrile, (c) distillation of stream 3 in a column, obtaining, as a superior product, a stream 4 containing 1,3-butadiene; in a lateral evacuation outlet of the column a stream containing 3-pentenenitrile and 2-methyl-3-butenonitrile, and, as product of the discharge, a stream 6, containing the catalyst, which is at least one; (d) distillation of stream 5, obtaining, as the upper product, a stream 7 containing 2-methyl-3-butenonitrile, and, as product of the discharge, a stream 8 containing 3-pentenenitrile.

Step (a) of the process comprises the reaction of 1,3-butadiene and hydrocyanic acid with at least one catalyst. As catalysts, complexes of nickel (0) catalysts are used.

In the case of Ni (0) complexes containing phosphorus ligands and / or free phosphorus ligands, these are preferably homogeneously dissolved nickel (0) complexes.

The phosphorus ligands of the nickel (0) complexes and the free phosphorus ligands are preferably selected from mono- or bidentate phosphines, phosphites, phosphinites and phosphonites.

The phosphorus ligands preferably have the formula I: P ^ R1) (X2R2) (X3R3) (I) By compound I is meant, in the sense of the present invention, a single compound or a mixture of various compounds of the formula above.

According to the invention, X1, X2, X3 are, independently of one another, oxygen or a single bond. In the case that all groups X1, X2 and X3 represent single bonds, compound I represents a phosphine of formula P (R1R2R3) with the meanings given to R1, R2 and R3 in this description.

In case two of the groups X1, X2 and X3 represent single bonds and one represents oxygen, the compound I represents a phosphinite of the formula PÍOR ^ ÍR2) (R3) or P (RX) (OR2) (R3) or P (R1) (R2) (OR3) with the meanings indicated for R1, R2 and R3 below.

In case one of the groups X1, X2 and X3 represents a single bond and two represent oxygen, the compound I represents a phosphonite of the formula P (OR1) (OR2) (R3) or P (R1) (OR2) ( OR3) or P (ORx) (R2) (OR3) with the meanings given for Rx, R2 and R3 in this description.

In a preferred embodiment, all groups X1, X2 and X3 should represent oxygen, so that compound I profitably represents a phosphite of the formula P1OR1 (OR2) (OR3) with the meanings indicated for R1, R2 and R3 later.

According to the invention, R1, R2 and R3 represent, independently of one another, identical or different organic radicals. As R.sub.1, R.sub.2 and R.sub.3 are independently selected from each other, 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'-bifolol. The groups R1, R2 and R3 can be linked together directly with one another, ie not through the central phosphorus atom. Preferably, the groups R1, R2 and R3 are not directly linked to one another.

In a preferred embodiment, radicals selected from the group consisting of phenyl, o-tolyl, m-tolyl and p-tolyl are taken into account as groups R1, R2 and R3. In a particularly preferred embodiment, they should, in such a case, be phenyl groups at most two of the groups R1, R2 and R3.

In another preferred embodiment, in such a case, at least two of the groups Rx, R2 and R3 should be o-tolyl groups.

As particularly preferred compounds I, those of the formula I-a can be applied (o-tolyl-0-) w (m-tolyl-0-) x (p-tolyl-0-) and (phenyl-0-) z P (I-a) meaning w, x, y and z a natural number and the following conditions are in force: w + x + y + z = 3 w, z < 2.

I a compounds of that kind are for example (p-tolyl-0-) (phenyl-0-) 2P, (m-tolyl-O) (phenyl-O-) 2P, (o-tolyl-0-) (phenyl) -O-) 2P, (p-tolyl-O-) 2 (phenyl-O-) P, (m-tolyl-0-) 2 (phenyl-0-) 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-) 3P, (m-tolyl-O-) (p-tolyl -O-) 2P, (o-tolyl-O-) (p-tolyl-O-) 2P, (m-tolyl-0-) 2 (p-toluyl-0-) P, (o-tolyl-0- ) 2 (p-tolyl-O-) P, (o-tolyl-O-) (m-tolyl-O-) (p-tolyl-O) P, (m-tolyl-O) 3P, (o-tolyl -0-) (m-tolyl-O) 2 P (o-tolyl-O) 2 (m-tolyl-O) P, or mixtures of those compounds.

Mixtures containing '(m-tolyl-O-) 3P, (m-tolyl-O-) 2 (p-tolyl-0-) P, (m-tolol-O-) (p-tolyl-O-) 2P , and (p-tolyl-O-) 3P can be obtained, for example, by reacting a mixture containing m-cresol and p-cresol, in particular, in a 2: 1 molar ratio, as it occurs in the preparation petroleum distillator, with a phosphorus trihalogenide, such as phosphorus trichloride.

In another, equally preferred embodiment, the phosphites of the formula I b, described in more detail in DE-A 199 53 058, are considered as phosphorus ligands: P (0-Rx) x (0-R2) and (0-R3) 2 (0-R4) p (I b) R1 being: an aromatic radical with a C? -C? 8 alkyl substituent, in position or with respect to the oxygen atom linking the phosphorus atom with the aromatic system, or with an aromatic substituent in position or with respect to the oxygen that joins the phosphorus atom with the aromatic system, or with an aromatic system condensed in position or with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, R2: an aromatic radical with an alkyl substituent C? -C? B, in position m with respect to the oxygen atom joining the phosphorus atom with the aromatic system, or with an aromatic substituent in position m with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, or with an aromatic system condensed in position m with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, carrying the aromatic radical in position or with respect to the oxygen atom that binds the phosphorus atom with the aromatic system, a hydrogen atom, R3: an aromatic radical with a C? -C18 alkyl substituent, in position p with respect to the oxygen atom linking the phosphorus atom with "the aromatic system, or with an aromatic substituent in position p with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, carrying the aromatic radical in position or with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, a hydrogen atom, R4: an aromatic radical carrying, in position or, m and p with respect to the oxygen atom linking the phosphorus atom with the aromatic system, other substituents than those defined for R1, R2 and R3, carrying the aromatic radical in position or with with respect to the oxygen atom that joins the phosphorus atom with the aromatic system, a hydrogen atom, x: 1 or 2 ,.

And z, p: independently of each other, 0, l or 2, with the proviso that x + y + z + p = 3.

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

As radical R2, 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.

As radical R3, p-tolyl, p-ethyl-phenyl, p-propyl-phenyl, p-isopropyl-phenyl, p-butyl-phenyl, p-sec-butyl-phenyl, p-tert-butyl-phenyl, advantageously enter. or (p-phenyl) -phenyl.

The radical R is preferably phenyl.

Preferably, p is equal to 0. For the indices x, y, z and p in compound I b the following possibilities are given: Preferred phosphites of the formula I b are those in which p is equal to zero and R1, R2 and R3 are, independently of one another, selected from o-isopropyl-phenyl, m-tolyl and p-tolyl, and R4 is phenyl.

Particularly preferred phosphites of the formula I b 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 indicated in the table above; in addition they are those in which R1 is the o-tolyl radical, R2 is the m-tolyl radical and R3 is the p-tolyl radical, with the indices indicated in the table; also those in which R1 is the 1-naphthyl radical, R2 is the m-tolyl radical and R3 is the p-tolyl radical, with the indices indicated in the table; also those in which R1 is the o-tolyl radical, R2 is the. 2-naphthyl radical and R3 is the p-tolyl radical, with the indices indicated in the table; and finally those in which R1 is the o-isopropyl-phenyl radical, R2 is the 2-naphthyl radical and R3 is the p-tolyl radical, with the indices indicated in the table; as well as mixtures of those phosphites.

The phosphites of the formula I b can be obtained a) reacting a phosphorus trihalogenide with an alcohol selected from the group consisting of RxOH, ROH, R30H and ROH, or mixtures of these, thus obtaining a monoester of dihalogen-phosphorous acid, b) reacting said dihalophosphorous acid monoester with an alcohol selected from the group consisting of R 10 H, R 2 OH, R 3 OH and R 4 OH, or mixtures thereof, thereby obtaining a diester of monohalogenous phosphorous acid, and c) by reacting said diester of monohalophosphorous acid with an alcohol selected from the group consisting of R 10 H, R 2 OH, R 3 OH and R40H, or mixtures thereof, thus obtaining a phosphite of formula I-b.

The reaction can be carried out in three separate steps. Likewise, two of these three steps can be combined, that is a) with b) or b) with c). As an alternative, the three steps a), b) and e) can be combined.

By doing so, appropriate parameters and appropriate amounts of alcohols selected from the group consisting of R ^ H, R2OH, R30H and R40H, or mixtures thereof, can be readily determined by some simple preliminary tests.

As a phosphorus trihalogenide, all phosphorus trihalogenides are taken into account, preferably those in which they are applied, such as halide, Cl, Br, I, in particular Cl, as well as mixtures of these. It is also possible to use, as phosphorus trihalide, mixtures of halogen-substituted phosphines in the same or different manner. PC13 is particularly preferred. Further details regarding the reaction conditions in the preparation of the phosphites I b and in terms of the preparation result from DE-A 199 53 058.

The phosphites I b can also be used as a mixture of various phosphites I b as ligands. Such a mixture can occur, for example, in the preparation of the phosphites I b.

It is certainly preferred that the phosphorus ligand be multidentate, in particular bidentate. Therefore, the ligand used preferably has formula II in which X11, X12, X13, X21, X22, X23 mean, independently of each other, oxygen or a single bond, R11, R12 signify, independently of one another, identical or different organic radicals, simple or compound bridged, R1, R2 signify, independently of one another, identical or different organic radicals, simple or compound bridged, And it means a bridge group.

By compound II is meant, in the sense of the present invention, a simple compound or a mixture of various compounds of the above-mentioned formula.

In a preferred embodiment, X11, X12, X13, X21, X22, X23 can represent oxygen. In this case, the bridge group Y is linked with phosphite groups.

In another preferred embodiment, X11 and X12 can represent oxygen and X13, a single bond, or X11 and X13 represent oxygen and X12, a single bond, so that the phosphorus atom surrounded by X11, X12 and X13 is the central atom of a phosphonite. In this case, X21, X22 and X23 can represent oxygen, or X21 and X22 represent oxygen and X23 a single bond, or X21 and X23 represent oxygen and X22 a single bond, or X23 represent oxygen and X21 and X22 represent a link simple, or X21 represent oxygen and X22 and X23 a single bond, or X21, X22 and X23 represent a simple bond, so that the atom of phosphorus surrounded by X21, X22 and X23 is the central atom of a phosphite, a phosphonite, a phosphinite or a phosphine, preferably a phosphonite.

In another preferred embodiment, X13 can represent oxygen and X11 and X12 represent a single bond, or X11 represent oxygen and X2 and X represent a single bond, so that the phosphorus atom surrounded by X11, X12 and X13 is the central atom of a phosphonite. In such a case, X21, X22 and X23 can represent oxygen, or X23 represent oxygen and X21 and X22 a single bond, or X21 represent oxygen and X22 and X23 a single bond, or X21, X22 and X23 represent a simple link , so that the phosphorus atom surrounded by X21, X22 and X23 is the central atom of a phosphite, of a phosphinite or of a phosphine, preferably of a phosphinite.

In another preferred embodiment, X11, X12 and X13 may represent a single bond, such that the phosphorus atom surrounded by X11, X12 and X13 is the central atom of a phosphine. In this case, X21, X22 and X23 can represent oxygen, or X21, X22 and X23 represent a single bond, so that the phosphorus atom surrounded by X21, X22 and X23 is the central atom of a phosphite or a phosphine , preferably of a phosphine.

Suitable bridging groups Y are preferably substituted aryl groups, for example, with alkoyl 1.-C4 / halogen such as fluorine, chlorine, bromine, halogenated alkyl such as trifluoromethyl, aryl such as phenyl, or unsubstituted aryl groups , preferably those having from 6 to 20 carbon atoms within the aromatic system, in particular pyrocatechol, bis (phenol) or bis (naphthol).

The radicals R11 and R12 can represent, independently of one another, identical or different organic residues. It is considered advantageous that as radicals R11 and R12, aryl radicals are taken into account, preferably those having from 6 to 10 carbon atoms, and which can be unsubstituted or substituted once or several times, in particular with C? -C4 alkyl, halogen such as fluorine, chlorine, bromine, halogenated alkyl as trifluoromethyl, aryl as phenyl, or with unsubstituted aryl groups.

The radicals R21 and R22 can represent, independently of one another, identical or different organic residues. It is considered advantageous that, as radicals R21 and R22, aryl radicals, preferably those having 6 to 10 carbon atoms, which can be unsubstituted or substituted one or more times, in particular with C3-C4 alkyl, are considered. , halogen as fluorine, chlorine, bromine, halogenated alkyl as trifluoromethyl, aryl as phenyl, or with unsubstituted aryl groups.

The radicals R11 and R12 can be simple or compounds bridged. Also radicals R21 and R22 can be simple or compounds bridged. The radicals R11, R12, R21 and R22 may all be simple, two compounds joined by bridges and two simple, or all compounds bridged together, in the manner in which it has been described.

In a particularly preferred embodiment, the compounds of the formulas I, II, III, IV and V mentioned in US 5,723,641. In a particularly preferred embodiment, the compounds of the formulas I, II, III, IV, V, VI and VII mentioned in US 5,512,696, in particular, those applied therein in examples 1 to 31. In a particularly preferred embodiment, the compounds of the formulas I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV and XV mentioned in the document are taken into account US 5,821,378, in particular, those applied therein in examples 1 to 73.

In a particularly preferred embodiment, the compounds of the formulas I, II, III, IV, V and VI mentioned in US 5,512,695, in particular, those applied therein in examples 1 to 6. In a particularly preferred embodiment, the compounds of the formulas 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 applied there in Examples 1 to 66.

In a particularly preferred embodiment, the compounds mentioned in US 6,127,567 and applied therein in examples 1 to 29 are taken into account. In a particularly preferred embodiment, the compounds of the formulas I are taken into account , II, III, IV, V, VI, VII, VIII, IX and X mentioned in US 6,020,516, in particular, those applied therein in examples 1 to 33. In a particularly preferred embodiment, they are into account the compounds mentioned in US Pat. No. 5,959,135, and applied therein in Examples 1 to 13.

In a particularly preferred embodiment, the compounds of the formulas I, II and III mentioned in document 5,847,191 are taken into account. In a particularly preferred embodiment, the compounds mentioned in US 5,523,453 are taken into account, especially the compounds represented therein in formulas 1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 and 21. In a particularly preferred embodiment, the compounds mentioned in WO 01/14392 are taken into account, preferably the compounds represented in formulas V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XXI, XXII, XXIII.

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

In a particularly preferred embodiment, the compounds mentioned in the German patent application DE 100 380 37 are taken into account. In a particularly preferred embodiment, the compounds mentioned in the German patent application are taken into account. DE 100 460 25. In a particularly preferred embodiment, the compounds mentioned in the German patent application DE 101 502 85 are taken into account.

In a particularly preferred embodiment, the compounds mentioned in the German patent application DE 101 502 86 are taken into account. In a particularly preferred embodiment, the compounds mentioned in the German patent application DE are taken into account 102 071 65. In another particularly preferred embodiment of the present invention, the phosphorus chelate ligands mentioned in US 2003/0100442 Al are taken into account.

In another particularly preferred embodiment of the present invention, the ligands of phosphorus chelates mentioned in the previously published German patent application DE 103 50 999.2 of 10/30/2003 are taken into account.

The compounds described I, 1 a, I b and II, as well as their preparation are known per se. As the phosphorus ligand, mixtures containing at least oxides of the compounds I, 1 a, 1 b and II can also be used.

In a particularly preferred embodiment of the process according to the invention, the phosphorus ligand of the nickel complex (0) and / or the phosphorus-free ligand selected from tritolylphosphite, phosphorus-containing bidentate chelate ligands, as well as the phosphites of the formula I b P (0-Rx) x (O-R2) i (0-R3) z (0-R4) p (Ib) wherein R x, 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 of each other, 0, 1 or 2, with the proviso that x + yi + z + p = 3; and its mixtures.

Step (a) of the method according to the invention can be carried out in any appropriate device, known to the person skilled in the art. For the reaction, conventional equipment is taken into account 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, such as agitation boiler reactors, bubble reactors with loop circulation, reactors with gas circulation, bubble columns or tubular reactors, in each case eventually with devices to dissipate the heat of the reaction. The reaction can be carried out - in several teams, such as in two or three.

In a preferred embodiment of the method according to the invention, reactors with a characteristic of remixing or cascades of reactors with characteristics of remixing were obtained. The cascades of reactors with a remixing characteristic that are operated with a transverse current with respect to the dosage of hydrocyanic acid were particularly advantageous.

Hydrocyanation can be carried out in the presence or absence of a solvent. When a solvent is used, it must be liquid at the given reaction temperature and the reaction pressure given and inert to the unsaturated compounds and at least one catalyst. In general, hydrocarbons are used as solvents, for example, benzene or xylene, or nitriles, for example, acetonitrile or benzonitrile. However, as a solvent, a ligand is preferably used.

The reaction can be carried out batchwise, continuously or semicontinuously.

The hydrocyanation reaction can be carried out by providing the device with all the reagents. However, it is preferred that the device is filled with the catalyst, the unsaturated organic compound and eventually the solvent. Preferably, the gaseous hydrocyanic acid floats on the surface of the reaction mixture or is introduced through the reaction mixture. Another procedure to equip the device is to fill it with the catalyst, hydrocyanic acid and eventually the solvent and slowly feed the unsaturated compound into the reaction mixture. Alternatively, it is also possible for the reactants to be introduced into the reactor and for the reaction mixture to be brought to the reaction temperature, at which the hydrocyanic acid is poured into the mixture. Beyond this, hydrocyanic acid can also be added before heating to the reaction temperature. The reaction is carried out under conventional hydrocyanation conditions in terms of temperature, atmosphere, reaction time, etc.

Preferably, the hydrocyanation is carried out continuously in one or several process steps under agitation. If several process steps are used, then it is preferred that the process steps be connected in series. In this case, the product is passed directly from a process step to the next process step. The hydrocyanic acid can be added directly in the first stage of the process or between the various stages of the process.

When the process according to the invention is carried out in semi-continuous operation, it is then preferred that the catalyst components and 1,3-butadiene are placed in the reactor while hydrocyanic acid is dosed during the entire reaction time in the reaction mixture. .

The reaction is preferably carried out at absolute pressures of 0.1 to 500 MPa, particularly preferably 0.5 to 50 MPa, especially 1 to 5 MPa. The reaction is preferably carried out at temperatures of 273 to 473 K, with particular preference 313 to 423 K, in particular 333 to 393 K. In this case, average waiting times of the liquid phase of the reactor in the range of 0.001 to 100 hours, preferably from 0.05 to 20 hours, with special preference from 0.1 to 5 hours, in each case per reactor.

The reaction can be carried out in a liquid phase embodiment in the presence of a gas phase and optionally a suspended solid phase. In this case, the starting substances can be hydrocyanic acid and 1,3-butyl diene, in each case in a liquid or gaseous state.

The reaction can be carried out in another embodiment in liquid phase, where the pressure in the reactor is measured such that all substances such as 1,3-butadiene, hydrocyanic acid and at least one of the substances are added in a liquid state. a catalyst and are in the reaction mixture in the liquid phase. In this case there can be a solid phase suspended in the reaction mixture which can also be dosed together with at least one catalyst, for example, composed of degradation products of the catalyst system containing, among others, nickel (II) compounds .

In process step (a) a stream 1 is obtained which contains 3-pentenenitrile, 2-methyl-3-butenonitrile, at least one catalyst and unreacted 1,3-butadiene, as well as unreacted hydrocyanic acid radicals. This stream 1 preferably has the following composition: 1 to 80% by weight, with particular preference 5 to 50% by weight, of at least one catalyst, 0.1 to 50% by weight, with particular preference 1 to 25% by weight 1,3-butadiene, 1 to 80% by weight, with particular preference 10 to 50% by weight, of pentenonitriles comprising trans-3-pentenenitrile, 2-methyl-3-butenonitrile, as well as other pentenonitrile isomers and 0.1 ppm by weight to 10% by weight, with special preference 10 ppm by weight to 1% by weight, of hydrocyanic acid, in each case based on the total mass of stream 1.

Stream 1 containing 3-pentenenitrile, 2-methyl-3-butenonitrile, at least one catalyst and unreacted 1,3-butadiene, then passes in process step (b) to a distillation device. In this distillation device, a distillation of stream 1 takes place, obtaining a stream 2 rich in 1,3-butadiene as an upper product and a stream 3 poor in 1,3-butadiene as a discharge product, which contains 3-pentenenitrile , at least one catalyst and 2-methyl-3-butenonitrile.

Step (b) of the process according to the invention can be carried out in any suitable device known to the person skilled in the art. Equipment is suitable for distillation as described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., Vol. 8, John Wiley & Sons, New York, 1996, pages 334-348, such as columns with perforated bottoms, columns with bubble plates, packing columns, columns with filling bodies or single-stage evaporators, such as gravity evaporator, thin-film evaporator, flash evaporator, multistage helical tube evaporator, natural circulation evaporator or forced circulation instant evaporator. The distillation can be carried out in several equipment, for example two or three, preferably in a single equipment.

In a preferred embodiment of the process according to the invention, there are added parts of the column with structured packing in the distillation device that generate preferably between 2 and 60, especially between 3 and 40, especially between 4 and 20, levels from separation.

In a particularly preferred embodiment of the process according to the invention, at least one step of the evaporator corresponding to the distillation device of process step (b) is carried out in such a way that the material to be evaporated suffers the least thermal damage possible, for example, by means of molecular gravity evaporators, multistage helical tube evaporators, thin-film evaporators or short-path evaporators by short contact times of the material with the evaporator surface and temperatures as low as possible of the evaporator surfaces.

In a preferred embodiment of the process according to the invention, the distillation device of process step (b) is operated with a separate discharge, where a circulating current is carried from a first discharge of the distillation column in question. the evaporator, in relation to the current 3 in general much larger, the liquid outlet stream does not return directly to the first discharge, but is captured in a second discharge that is separated from the first discharge, current 3 is obtained from the second discharge and the remaining excess of the circulating flow of the evaporator is dropped in the first discharge, where as a stream 3 of the second discharge a mixture is obtained which, in contrast to the circulating current of the evaporator extracted from the first discharge, is impoverished in terms of low boiling fractions. In this case, a molecular evaporator by gravity is preferably used as the evaporator.

In another preferred embodiment of the process according to the invention, the distillation is carried out with average waiting times of the liquid phase in the area of the discharge of one or several distillation equipment together less than 10 hours, with special preference less than 5 hours, especially less than 1 hour.

In another preferred embodiment of the method according to the invention, the condensation in the upper part of the distillation device is carried out in such a way that a partial flow of the discharge from the upper part to the condenser is rinsed again.

The distillation can be carried out in a further preferred embodiment of the process according to the invention with a direct condenser, so that the condensation is carried out in a column section which is preferably provided with a structured column packing, a collecting container with under this packing, a liquid outlet of the collecting vessel, a pumping circuit connected to the liquid outlet with pump and heat exchanger, as well as at least one device for supplying the liquid stream pumped to the packing over the collecting vessel .

In order to obtain the highest possible performance of the process with respect to 1,3-butadiene, in spite of the only partial reaction of step (a), it is preferred that stream 2 rich in 1,3-butadiene recirculates to the procedure stage (a). The recirculation of stream 2 in process step (a) can also be carried out only partially.

In another embodiment, in the distillation of step (b), the necessary 1,3-butadiene can additionally be added for the reaction in process step (a) in the upper part of the column or in stream 2.

In another embodiment, the added 1,3-butadiene contains a stabilizer such as ter-butyl pyrocatechol or 2,6-di-ter. -butil-para-cresol, according to the description in "Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2000 Electronic Relay, chapter" Butadiene - 6. Stabilization, Storage and Transportation ".

In a particularly preferred embodiment of the process according to the invention, 1,3-butadiene applied directly in process step (a) or added in process step (b) and passed through stream 2 in the step of process (a) is released from the water and optionally from the stabilizer upon contact with the molecular sieve with a pore size of less than 10 Angstrom or upon contact with aluminum oxide.

In another particularly preferred embodiment, the 1,3-butadiene used directly in the process step (a) or supplied in stream 2 is used without stabilizer, wherein with an appropriate choice of the pressure conditions the condensation temperatures in the upper part of the distillation device of process step (b) to less than 293 K, in order to avoid a polymerization of 1,3-butadiene, especially in order to restrict the growth of popcorn polymeric seeds .

The absolute pressure in process step (b) is preferably from 0.001 to 100 bar, particularly preferably from 0.01 to 10 bar, in particular from 0.5 to 5 bar. The distillation is carried out in such a way that the temperature in the discharge of the distillation device is preferably from 30 to 140 ° C, particularly preferably from 50 to 130 ° C, in particular from 60 to 120 ° C. carried out in such a way that the condensation temperature in the upper part of the distillation device is preferably from -50 to 140 ° C, with special preference from -15 to 60 ° C, especially from 5 to 45 ° C. In a particularly preferred embodiment of the process according to the invention, the aforementioned temperature ranges are maintained both in the upper part and also in the discharge of the distillation device.

The return ratio at the top of the distillation device is preferably adjusted such that stream 2 contains 1 to 1000 ppm, particularly preferably 5 to 500 ppm, especially 10 to 200 ppm, of 2-methyl-3-. butenonitrile.

This contributes to the recirculated 1, 3-butadiene containing minor amount of 2-methyl-3-butenonitrile which reacts in process step (a) in methylglutardinitrile.

In process step (b), a stream 2 rich in 1,3-butadiene is obtained as the top product and a stream 3 is poor in 1,3-butadiene as the discharge product. The designation of the currents as rich or poor in 1,3-butadiene refers, in this case, to the 1,3-butadiene content of stream 1 applied in process step (b).

In a preferred embodiment of the process according to the invention, stream 2 rich in 1,3-butadiene contains a total of 50 to 100% by weight, with particular preference 80 to 100% by weight, in particular 85 to 99% by weight , 1, 3-butadiene and isomers of butene, as well as in total 0 to 50% by weight, with particular preference 0 to 20% by weight, in particular 10 ppm by weight to 1% by weight, of pentenenitrile isomers, of which 2-methyl-3-butenonitrile and trans-3-pentenenitrile are essentially represented in stream 2.

In a preferred embodiment of the process according to the invention, the 3-butadiene-poor stream 3 contains in total 0 to 50% by weight, with particular preference 1 to 30% by weight, in particular 2 to 20% by weight , of 1,3-butadiene and butene isomers with respect to the total mass of the stream 3. In a particularly preferred embodiment of the process according to the invention, the aforementioned 1,3-butadiene specifications are obtained, both in current 2 as well as current 3.

The 3-butadiene-poor stream 3 from process step (b), which contains 3-pentenenitrile, at least one catalyst and 2-methyl-3-butenenitrile, is then passed to the process step (c) ) to a distillation device. In this distillation device, a distillation of stream 3 is produced by obtaining a stream 4 as an upper product containing 1,3-butadiene, from a stream 5 in a lateral evacuation of the column containing 3-pentenenitrile and 2-methyl-3. -butenonitrile, and a stream 6 as a discharge product containing at least one catalyst.

Step (c) of the process according to the invention can be carried out in any appropriate device known to the person skilled in the art. For this distillation equipment is suitable as described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed., Vol. 8, John Wiley & Sons, New York, 1996, pages 334-348, such as columns with perforated bottoms, columns with bubble plates, packing columns, columns with filling bodies or single-stage evaporators, such as gravity evaporator, thin-film evaporator, flash evaporator, multiphase helical tube evaporator, natural circulation evaporator or forced circulation instant evaporator. The distillation can be carried out in several teams, such as two or three, preferably in a team.

In a particularly preferred embodiment, the distillation device in process step (c) comprises at least one distillation column with a stripping section. Particularly preferred is an embodiment which contains as a distillation device in process step (c) only one distillation column which is operated only with separation operation.

The column of. Distillation in the distillation device is preferably equipped with a structured packing that generates 2 to 50, with particular preference 3 to 40, in particular 4 to 30 theoretical levels of separation.

In a particularly preferred embodiment of the method according to the invention, at least one of the levels of the evaporator corresponding to the distillation device of process step (c) is carried out in such a way that the material to be evaporated suffers the least possible thermal damage , as is achieved, for example, by the molecular evaporator by gravity, the evaporator of multiphase helical tubes, the thin-film evaporator or the short-path evaporators, by brief contact times of the material on the surface of the evaporator and the smaller ones possible temperatures of the evaporator surfaces.

The absolute pressure in process step (c) is preferably from 0.001 to 10 bar, particularly preferably from 0.010 to 1 bar, in particular from 0.02 to 0.5 bar. The distillation is carried out in such a way that the temperature at the discharge of the distillation device is preferably from 30 to 140 ° C, particularly preferably from 50 to 130 ° C, especially from 60 to 120 ° C. The distillation is carried out in such a way that the condensation temperature in the discharge of the distillation device is preferably from -50 to 140 ° C, with special preference from -15 to 60 ° C, especially from 5 to 45 ° C. In a particularly preferred embodiment of the process according to the invention, the aforementioned temperature ranges are preserved both in the upper part and also in the discharge of the distillation device.

In a further preferred embodiment of the method according to the invention, a discharge temperature of 140 ° C. is not exceeded in process steps (b) and (c).

In another preferred embodiment of the process according to the invention, the distillation is carried out with mean waiting times of the liquid phase in the area of the discharge of one or several distillation equipment together less than 10 hours, with special preference less than 5 hours, especially less than 1 hour.

In a particularly preferred embodiment of the process according to the invention, the distillation is carried out with average waiting times of the liquid phase in the area of the discharge of one or more distillation equipment in the process steps (b) and (c) together less than 10 hours, with special preference less than 5 hours, especially less than 1 hour.

In the distillation of process step (c), a stream 4 is obtained as an upper product. This stream 4 preferably contains a total of 50 to 100% by weight, with particular preference 80 to 100% by weight, in particular 90 to 99.9% by weight, of 1,3-butadiene and isomers of butene, and in total 0 to 50% by weight, with particular preference 0 to 20% by weight, especially 10 ppm by weight to 10% by weight of pentenenitrile isomers, of which essentially 2-methyl-3-butenonitrile and trans-3 are represented -pentenenitrile in stream 4.

In a preferred embodiment of the process according to the invention, the stream 4 is obtained in gaseous form in at least one condenser in the upper part of the distillation device, wherein at least one condenser condenses pentenonitrile components from the vapor stream. from the distillation device of process step (c) in the aforementioned range of condensation conditions such as pressure and temperature at least partially, and are fed back into the column at least partially in liquid form as a stream containing pentenonitriles, as well as 1,3-butadiene and butene isomers.

In order to increase the yield of the process with respect to the 1,3-butadiene applied in the process according to the invention, it is preferred that the stream 4 recirculates in process step (a). The recirculation of stream 4 in process step (a) can also be carried out only partially. In this case, the stream 4 can be subjected before its recirculation in addition to a technical processing process, for example, a high pressure condensation.

In a particularly preferred embodiment of the process according to the invention, stream 4 is recirculated through process step (b) to process step (a), wherein the pentenonitrile components, which may be contained in stream 4 according to the distillation conditions, are preferably separated from stream 4 by recirculation of stream 4 in the distillation device of process step (b) and finally only the ratio of 1,3-butadiene and isomers is recirculated of butene of stream 4 through stream 2 in step (a).

In process step (c), in addition to current 4, another stream 5 is obtained which is obtained in a lateral evacuation of the column. This stream contains 3-pentenenitrile and 2-methyl-3-butenonitrile, in addition to other pentenenitrile isomers and residual components of 1,3-butadiene and butene isomers. The proportion of 3-pentenenitrile and 2-methyl-3-butenonitrile in stream 5 is, in total, preferably from 80 to 100% by weight, with particular preference from 85 to 99.998% by weight, especially from 90 to 99, 9% by weight, in each case referred to the stream 5. The ratio of 1,3-butadiene and isomers of butene in stream 5 is preferably from 0 to 20% by weight, with particular preference from 10 ppm by weight to 5. % by weight, in particular from 50 ppm by weight to 2% by weight, in each case based on the current 5. The stream 5 is preferably extracted in the form of steam.

The lateral evacuation of the distillation device is preferably below the admission of the stream 3, with particular preference in a position corresponding to 1 to 20, in particular 2 to 10 levels of distillation separation below the admission of the current 3.

As a discharge product, a stream 6 containing at least one catalyst, such as trans-3-pentenenitrile and 2-methyl-3-butenonitrile, is obtained in process step (c). The proportion of pentenenitrile isomers in stream 6 is in total preferably from 0.1 to 80% by weight, with particular preference from 5 to 50% by weight, in particular from 10 to 40% by weight, in each case based on the current 6.

In this case it is especially preferred that the stream 6 in the process step (a) of the hydrocyanate recirculates at least in part, where [...] a regeneration, as described in the document. In another embodiment of the method according to the invention, the distillation device of process step (c) is operated with one or more liquid side or vapor evacuations, above or below the current admission site 3, in order to extract expulsion or recirculation currents.

In addition, it is also possible to use the stream 6 of process step (c) wholly or partly as stream of catalysts for other hydrocyanates, for example, for the hydrocyanation of 3-pentenenitrile. When the catalyst stream 6 is used for the hydrocyanation of the 3-pentenenitrile, it is preferred that the content of 2-methyl-3-butenonitrile in this stream of catalysts 6 be as low as possible.

For this reason, in a preferred embodiment of the method according to the invention in process step (c), the position of the lateral evacuation and the total amount of the theoretical levels of separation of the distillation device in the process step ( c) is chosen such that in the discharge the stream 6 is obtained with a concentration of 2-methyl-3-butenonitrile which is reduced in comparison with the stream 5, where the reduction refers to the ratio of the concentrations of 2-methyl-3-butenonitrile with respect to trans-3-pentenenitrile. Especially preferred are 1 to 50, in particular 2 to 20 levels of separation by distillation between the position of the lateral evacuation and the discharge. This depletion of 2-methyl-3-butenonitrile can also possibly take place in a separate device, designed as a distillation column with a separation part. Preferably, the proportion of 2-methyl-3-butenonitrile in the catalyst stream 6 is from 0 to 5% by weight, with particular preference from 10 ppm by weight to 2% by weight, in particular 50 ppm by weight at 0.5% by weight, relative to the catalyst stream 6. In another embodiment of the method according to the invention, the stream 6 can be supplemented once a partial stream 6b has been withdrawn for the purpose of ejection, regeneration or use and another method of hydrocyanation, for example, of 3-pentenontrile in adiponitrile, by a new catalyst stream, in order to ensure the necessary amount of at least one catalyst in process step (a). The new catalyst stream can come from a directed synthesis, a regeneration process or a process for recovering the catalyst from a hydrocyanation process, especially from an extraction process step in a process to hydrocyanate 3-pentenenitrile in adiponitrile.

In a preferred embodiment, the stream of new catalysts is brought directly to the process step (a) or to the stream 6 according to the place from which "the partial stream was extracted.

In a further preferred embodiment, a stream of new catalysts is passed in the distillation device of process step (c), in order to be able to control the pentenenitrile content of the entire catalyst stream of the process step (a) in the limits indicated above.

In a further preferred embodiment of the process according to the invention, the amount of catalyst ejection and thus the necessary additional amount of new catalyst are measured such that in the catalyst circuit the content of metliglutardini-rile does not exceed 50% by weight , with special preference does not exceed 20% by weight, in particular does not exceed 10% by weight, in each case referred to the current of the catalyst circuit, in order to have the catalytic current expelled in a regeneration with the least amount of inhibitory effects of methylglutardinitrile to capture nickel (0).

In another preferred embodiment of the method according to the invention, the amount of catalyst removal and thus the necessary additional amount of new catalyst are measured such that in the catalyst circuit the content of nickel (0) complexes is not less than 0.05% by weight, preferably not less than 0.1% by weight, in particular not less than 0.2% by weight, in each case with respect to the catalyst circuit and in each case calculated as nickel ( 0) metallic, in order to ensure the activity of the hydrotreating catalyst despite the losses of nickel (0) complexes during the reaction in step (a) or during the distillation process in steps (b) and (c) ), especially during the reaction in step (a).

In the process according to the invention, it is particularly preferred when the stream 5 is obtained in the lateral evacuation in the process step (c) in the form of steam.

In a further preferred embodiment of the method according to the invention it is possible to pass current 1, which is obtained in process step (a), excluding process step (b), directly to process step (c).

The stream 5 is then passed in the process step (d) to another distillation device. In this distillation device a distillation of the stream 5 is produced by obtaining a stream 7, which contains 2-methyl-3-butenonitrile, and a stream 8 containing 3-pentenenitrile. The stream 7 is obtained in the upper part of the distillation device, while the stream 8 is obtained in the discharge of the distillation device.

In this case, in a particularly preferred embodiment of the process according to the invention, the stream 5, optionally obtained as gas side discharge, is passed in gaseous form to the distillation device of process step (d), where the pressure at the position of the intake site for the stream 5 in the distillation device of the process step (d) is less than or equal to the pressure at the position of the side discharge for the stream 5 in the distillation device of the process step (c).

The procedure variants in which the level pressure is not excluded from the scope of this description are not excluded. (d) is freely chosen and the gaseous stream 5 is eventually compressed at a higher pressure than at the extraction site in (c), in order to be brought to the level (d).

Step (d) of the process according to the invention can be carried out in any appropriate equipment known to the skilled person. For this distillation equipment is suitable as described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, - 4 to Ed., Vol. 8, John Wiley & Sons, New York, 1996, pages 334-348, such as columns with perforated bottoms, columns with bubble plates, packing columns, columns with filling bodies or single-stage evaporators, such as gravity evaporator, thin-film evaporator, flash evaporator, multiphase helical tube evaporator, natural circulation evaporator or forced circulation instant evaporator. The distillation can be carried out in several teams, such as in two or three, preferably in a single team.

The columns preferably contain structured packings. In this case, the structured packings preferably generate 5 to 100, with special preference 10 to 80, in particular 15 to 50 theoretical levels of separation.

The pressure in process step (d) is preferably from 0.001 to 100 bar, with particular preference from 0.01 to -20 bar, especially from 0.05 to 2 bar. The distillation is carried out in such a way that the temperature at the discharge of the distillation device is preferably from 30 to 250 ° C, particularly preferably from 50 to 200 ° C, in particular from 60 to 180 ° C. carried out in such a way that the condensation temperature in the upper part of the distillation device is preferably from -50 to 250 ° C, particularly preferably from 0 to 180 ° C, in particular from 15 to 160 ° C. In a particularly preferred embodiment of the method according to the invention, the aforementioned temperature ranges are preserved both in the upper part and in the discharge of the distillation device.

In an embodiment of the process according to the invention, the stream 7, which is obtained in process step (d), can be recirculated in process step (a) and / or in process step (b), in wherein the reaction conditions in process step (a) or the waiting time of the fluid phase in the discharge of process step (b) are selected such that 2-methyl-3 is at least partially isomerized -butenonitrile in trans-3-pentenonitrile.

In another embodiment of the method according to the invention, the stream 7 is obtained as a side discharge stream in the distillation device of process step (d), wherein as the upper product of this distillation column a stream is obtained which it contains, in addition to 2-methyl-3-butenonitrile, essentially (Z) -2-methyl-2-butenonitrile and optionally 1,3-butadiene and isomers of butene, as well as vinylcyclohexene and ethylidenecyclohexene.

The content of trans-3-pentenenitrile in stream 7 is preferably from 0 to 50% by weight, particularly preferably from 100 ppm by weight to 20% by weight, in particular from 1 to 15% by weight. The content of 2-methyl-3-butenonitrile in stream 8 is preferably from 0 to 10% by weight, with particular preference from 5 ppm by weight to 5% by weight, in particular from 50 ppm by weight to 1% by weight .

The process according to the invention allows the preparation of 3-pentenenitrile and 2-methyl-3-butenonitrile in an integrated process which, by virtue of the possible practically complete recirculation of the 1,3-butadiene streams and the catalyst stream, It presents a high procedure yield for the substances of use. In this case, the temperatures and pressure ratios necessary for the distillative separation of 1,3-butadiene and the pentenenitrile isomers from the streams with catalyst content can be chosen so that, on the one hand, the temperatures of the evaporator of the discharge when carrying out the procedure, they are so low on a production scale with technically achievable waiting times that they do not preferentially cause damage to the catalysts and, on the other hand, the condensation of the products of the upper part of each of the stages of production takes place. distillation preferably at temperatures in which heat dissipation is possible at a justifiable economic cost.

An embodiment of the method according to the invention is explained in more detail by means of Figure 1.

Figure 1 shows a schematic representation of an embodiment of the method according to the invention. In the reactor Rl, 1,3-butadiene (1,3-butadiene), hydrocyanic acid (HCN) and a homogeneous catalyst of nickel (0) (CAT) are introduced. Hydrocyanation of 1,3-butadiene takes place in this reactor. In this case current 1 is formed, which contains essentially 3-pentenenitrile, 2-methyl-3-butenonitrile, the nickel (0), 1,3-butadiene and hydrocyanic acid catalyst. This stream is then passed to a distillation column Kl. Here a separation of the stream 1 takes place in a stream 2 which contains 1,3-butadiene and is recycled to the reactor Rl, and in a stream 3 containing 3-pentenenitrile, the nickel (0) and 2-methyl- catalyst. 3-butenonitrile.

The stream 3 is then passed to a second distillation column K2. Here there is a separation of the remaining 1,3-butadiene (stream 4) from stream 3 at the top of the column, its recirculation in the column Kl, as well as a separation of the catalyst with a stream 6 from the discharge of the column that is impoverished in 3-pentenenitrile and 2-methyl-3-butenonitrile. Stream 6 is recirculated in reactor Rl. In a lateral evacuation of column K2, a stream 5 is obtained. This stream contains 3-pentenenitrile and 2-methyl-3-butenonitrile. Stream 4 is recirculated in Kl.

Next, stream 5 is passed to a third distillation column K3. Here a separation occurs in stream 8, which contains 3-pentenenitrile and is extracted in the discharge from the column, and stream 7 which contains' 2-methyl-3-butenonitrile and is extracted in the upper part of the column of distillation.

Stream 8, which contains 3-pentenenitrile, can be fed into another hydrocyanation in adiponitrile.

The present invention is explained in more detail by means of the following exemplary embodiments.

In the examples the following abbreviations are used: HCN: hydrocyanic acid CAT: catalyst BD: 1,3-butadiene REG: regeneration stage Example 1: Example 1 is clarified by means of Figure 2.

In Example 1, a system of catalysts based on nickel complexes (0) with a mixture of ligands is used for the hydrocyanation of 1,3-butadiene. The mixture of ligands for hydrocyanation contains about 60 mole% by weight of tri (m / p-tolyl) phosphite and 40 mole% by weight of chelate phosphonite 1: In a process step (a) is. they carry the following streams in a bubble reactor with loop circulation Rl with a volume of 25 1, which is equipped with a nozzle, a pulse exchange tube, an external pumping circuit and a heat exchanger that is in the pumping circuit to dissipate the energy of the reaction and which is tempered at 357 K: (1) 10 kg / h of liquid hydrocyanic acid, unstable, and released from water by distillation, (2) 22 kg / h of commercially available 1,3-butadiene containing 0.25% by weight of cis-2-butadiene, which was treated by contact with aluminum oxide to remove water and the stabilizer, (3) 8 kg / h of 1,3-butadiene from column Kl of process step (b) (stream 2), so that a stream is obtained as total admission of 1,3-butadiene in reactor Rl of 30 kg / h containing 90% by weight of 1,3-butadiene, 5% by weight of cis-2-butene, as well as 5% by weight of 1-butene, (4) 21 kg / h of nickel (0) catalyst solution, obtained as in this example described below as stream 6a from column (K2) of the step o.e process (c).

The stream 1 extracted from the reactor Rl (63 kg / h) contains in total 11% by weight of 1,3-butadiene and cis-2-butene, equivalent to a 79% yield of 1,3-butadiene, as well as in total 63% by weight of pentenenitriles, 31% by weight of trans-3-pentenenitrile, 29% by weight of 2-methyl-3-butenenitrile, subordinate amounts of cis-3-pentenenitrile, trans-2-pentenenitrile, cis-2 -pentenenitrile, 4-pentenenitrile and low amounts of (Z) -2-methyl-2-butenonitrile and (E) -2-methyl-2-butenonitrile, as well as the catalyst components and degradation products of the catalyst and methylglutarnitrile.

The stream 1 is carried in a process step (b) to a distillation column K1 which is operated with a reinforcement and depletion section and which is equipped with a molecular evaporator by gravity and a separate discharge, and contains parts added to it. the structured packing column that generates 10 theoretical levels of separation. The Kl column is operated in the upper part with a direct condenser consisting of a column section with a total collector tank provided with a structured packing, pumping circuit and external heat exchanger. The column Kl is operated with an absolute pressure of 2.0 bar of pressure in the upper part, 288 K of temperature in the upper part and 363 K of temperature in the outlet of the discharge.

In the upper part of the column Kl the current 2 is obtained, which is dosed as recirculation current in the reactor R1 as originally described. The return ratio at the top of column Kl is adjusted such that stream 2 contains approximately 100 ppm of 2-methyl-3-butenonitrile.

In the discharge of the column Kl, 59 kg / h of a stream 3 containing 2.9% by weight of 1,3-butadiene, 4.6% by weight of cis-2-butene, 67% by weight of pentenenitriles, as well as additionally the catalyst components. The cis-2-butene is clearly enriched in relation to 1,3-butadiene with respect to admission.

Stream 3 is carried in a process step (c) to a distillation column K2, which is operated in separation operation and with molecular evaporator by gravity, upper condenser with final condenser, as well as pieces added in the structured packing column that generate 10 theoretical levels of separation. The column is operated with an absolute pressure of 150 mbar of pressure at the top, 329 K of temperature at the top and 373 K of temperature at the outlet of the discharge. The vapor stream of the column is partially condensed at 308 K and treated with a final condenser at 263 K. The current 4 thus depleted of 2-methyl-3-butenonitrile and other pentenonitriles is condensed in a compressor VI at an absolute pressure of 1.2 bar. The compressed gas stream condenses at 279 K, obtaining in large part a stream 4a (5 kg / h), where a partial stream 4b (approximately 50 Nl / h, containing 44% by weight of cis) is available in gaseous form. 2 -butene). The stream 4a is brought back in liquid form to the return part of the separate discharge of the column Kl.

From column K2, current 5 (40 kg / h), which contains approximately 50 ppm of 1,3-butadiene, 46% by weight of 2-methyl-3-butenonitrile and 48% by weight, is obtained in a gaseous lateral evacuation. of trans-3-pentenenitrile, as well as on a smaller scale (E) -2-methyl-2-butenonitrile and (Z) -2-methyl-2-butenonitrile together with other pentenonitrile isomers. The position of the lateral evacuation was chosen such that below the lateral evacuation in a depletion section the 2-methyl-3-butenonitrile component in the stream 6 obtained in the discharge relative to trans-3-pentenenitrile is depleted.

In column K2, 13 kg / h of a stream of catalyst 10 (stream 10) are carried in addition to the stream 3, which contains in total 73% by weight of pentenenitriles, 0.5% by weight of Ni (0), 18% by weight of mixture of ligands, as well as about 5% by weight of adiponitrile.

In column K2, the stream of catalyst 6, containing 0.5% by weight of Ni (0), approximately 100 ppm of 2-methyl-3-butenonitrile and 35% by weight of residual pentenonitriles is obtained at the discharge. Stream 6 is partially returned to reactor Rl (stream 6a) (21 kg / h). Another part (stream 6b: 5.4 kg / h) is brought to a regeneration (REG), in order to be applied after regeneration, for example, in Example 1 of the hydrocyanation of 3-pentenenitrile according to DE-A-102 004 004 683.

The stream 5 is carried in a process step (d) to a distillation column K3 which is equipped with an evaporator with circulation and a condenser of the upper part, as well as with a structured packing that generate 30 theoretical levels of separation. Column K3 is operated with an absolute pressure of 180 mbar of top pressure, 345 K of top temperature and 363 K of outlet temperature at discharge.

In column K3, 39 kg / h of a stream 9, which contains 54% by weight of trans-3-pentenenitrile, 23% by weight of 2-methyl-3-butenenitrile and 16% by weight of (Z) - are carried. 2-methyl-2-butenonitrile, as well as in smaller amounts other isomers of pentenonitrile. Stream 9 can be obtained, for example, as a pentenenitrile stream returned from a process for isolating 2-methyl-3-butenonitrile in 3-pentenenitrile, as described in Example 1 of DE-A-102 004 004 671.

In the upper part of column K3, 40 kg / h of a stream 7 are obtained, containing 10% by weight of trans-3-pentenenitrile, 68% by weight of 2-methyl-3-butenonitrile, 16% by weight of (Z) -2-methyl-2-butenonitrile, as well as in total 0.1% by weight of 1,3-butadiene and cis-2-butene. This stream can be fed in a process to isomerize 2-methyl-3-butenonitrile in 3-pentenenitrile, as described in Example 1 of DE-A-102 004 004 671.

In the discharge of column K3, 39 kg / h of stream 8 are obtained, which contains in total 97% by weight of trans-3-pentenenitrile, cis-3-pentenenitrile and 4-53 pentenonitrile, as well as about 100 ppm of 2-methyl-3-butenonitrile and about 1% by weight of (E) -2-methyl-2-butenonitrile.

Example 1 shows how a practically complete recovery of butadiene and catalyst results in a hydrocyanation process. In Example 1, the catalyst in column K1 and column K2 is separated in two stages under protection conditions, where in column K2 the nitrile stream can be obtained essentially without butadiene.

The composition of the previously recovered catalyst stream found in Example 1 is particularly suitable for the application in a process for hydrocyanate pentenenitrile in adiponitrile, since the stream 6 and thus also the stream 6b are obtained essentially free of 2-methyl-3. -butenonitrilo and butadieno.

Example 2 Example 2 is clarified by means of Figure 3 In Example 2 a system of catalysts based on nickel (0) complexes with chelate phosphite 2 as a ligand is used for the hydrocyanation of 1,3-butadiene: In a process step (a) the following streams are taken to a bubble reactor with circulation in Rla and Rlb loops with a volume of 12 1 each, which are equipped with a nozzle, a pulse exchange tube, an external pumping circuit and a heat exchanger that is in the pumping circuit to dissipate the energy of the reaction and which are tempered in 357 K: (1) 6 kg / h of liquid hydrocyanic acid, unstable, released from water by distillation of Rla, (2) 6 kg / h of liquid hydrocyanic acid, unstable, liberated from water by distillation of Rlb, (3). 25 kg / h of 1,3-butadiene customary in the market of Rla, containing 0.25% by weight of cis-2-butene, which was treated by contact with aluminum oxide to remove water and stabilizer, (4) 2 kg / h of 1,3-butadiene recirculated from column Kl in process step (b) of Rla (stream 2), so that as total admission of 1,3-butadiene to reactor Rl is obtained a current of 27 kg / h containing 98% by weight of 1,3-butadiene and in total 2% by weight of cis-2-butene and 1-butene, (5) 14 kg / hr of Rla nickel (0) catalyst solution, obtained as described below in this Example as stream '6a from column (K2) of process step (c).

The stream 1 extracted from the Rlb reactor (54 kg / h) contains in total 4% by weight of 1,3-butadiene and cis-2-butene, equivalent to a 94% yield of 1,3-butadiene, as well as in total 74% by weight of pentenenitriles, of which 33% by weight of trans-3-pentenenitrile, 37% by weight of 2-methyl-3-butenenitrile, subordinate amounts of cis-3-pentenenitrile, trans-2-pentenenitrile, cis -2-pentenenitrile, 4-pentenenitrile and low amounts of (Z) -2-methyl-2-butenonitrile and (E) -2-methyl-2-butenonitrile, as well as the catalyst components and degradation products of the catalyst and methylglutardinitrile .

The stream 1 is carried in a process step (b) to a distillation column Kl which is operated with a reinforcing part and which is equipped with a molecular evaporator by gravity, and contains added pieces of structured packing column which generate 4. theoretical levels of separation. The column Kl is operated in the upper part with a direct condenser which is composed of a column section with a total collector tank filled with filler bodies, a pumping circuit and an external heat exchanger. Column Kl is operated at an absolute pressure of 0.8 bar of pressure in the upper part, 263 K of temperature in the upper part and 393 K of outlet temperature in the discharge.

In the upper part of the column Kl the current 2 is obtained, which is dosed in the reactor Rla as recirculation current as described at the beginning. The return ratio in the upper part of the column K1 is regulated such that the stream 2 contains 0.1% by weight of 2-methyl-3-butenonitrile.

In the discharge of the column Kl, 52 kg / h of a stream 3 are obtained, which contains 0.3% by weight of 1,3-butadiene, 0.1% by weight of cis-2-butene, 76% by weight. weight of pentenenitriles, as well as additionally the catalyst components.

The stream 3 is carried within the process step (c) to a distillation column K2 which is operated in separation operation and which is equipped with molecular evaporator by gravity, upper condenser with final condenser, as well as parts added from the column of structured packing that generate 4 theoretical levels of separation. The column is operated at an absolute pressure of 70 mbar of pressure in the upper part, 333 K of temperature in the upper part and 373 K of outlet temperature in the discharge.

In column K2 the gaseous stream 5 is obtained at the upper outlet (40 kg / h), which contains 0.4% by weight of 1,3-butadiene, 54% by weight of 2-methyl-3-butenonitrile and 42% by weight. % by weight of trans-3-pentenenitrile, as well as on a smaller scale (E) -2-methyl-2-butenonitrile and (Z) -2-methyl-2-butenonitrile in addition to other pentenenitrile isomers.

In column K2, 3 kg / h of a catalytic current (stream 4), containing a total of 45% by weight of pentenenitriles, 1.5% by weight of Ni (0) and the chelate ligand obtained, for example, are carried. , by reaction of the nickel (0) complex (cyclooctadienyl) 2 with the chelate phosphite 2.

In the column K2, the catalyst stream 6, which contains 1.2% by weight of Ni (0), 0.3% by weight of 2-methyl-3-butenonitrile and 17% by weight of the pentenenitriles, is obtained at the discharge. remaining . The stream 6 is partly returned (stream 6a) in the reactor Rl (14 kg / h). Another part (stream 6b: 3.8 kg / h) is brought to a regeneration (REG), and can be applied after regeneration, for example, in the hydrocyanation of 3-pentenenitrile or possibly recirculated in the hydrocyanation of butadiene according to the process according to the invention.

'The stream 5 is carried in a process stage (d) to a distillation column K3, which is equipped with a circulation evaporator and an upper condenser as well as with structured packing, which generate 45 theoretical levels of separation. Column K3 is operated at an absolute pressure of 1.0 bar pressure at the top, 395 K temperature at the top and 416 K discharge temperature at the discharge.

In column K3, 24 kg / h of recirculation stream 9, which contains 70% by weight of trans-3-pentenenitrile, 14% by weight of 2-methyl-3-butenonitrile and 7% by weight of (Z), are carried. -2-methyl-2-butenonitrile, as well as in smaller amounts other pentenenitrile isomers. The stream 9 can be obtained, for example, as recirculated pentenenitrile stream from a process for isomerizing 2-methyl-3-butenonitrile in 3-pentenenitrile, as described in Example 2 of DE-A-102 004 004 671 In the upper part of column K3, 30 kg / h of a stream 7 are obtained, which contains 1% by weight of trans-3-pentenenitrile, 85% by weight of 2-methyl-3-butenonitrile, 8% by weight of (Z) -2-methyl-2-butenonitrile, as well as in total 3% by weight of 1,3-butadiene and cis-2-butene. The return ratio of column K3 is regulated in such a way that 1% by weight of 3-pentenenitrile is obtained in the upper part. This stream can be obtained from a process to εomerize 2-methyl-3-butenonitrile into 3-pentenenitrile, as described in Example 2 of DE-A-102 004 004 671.

In the discharge of column K3, 38 kg / h of stream 8 are obtained, which contains in total 97% by weight of trans-3-pentenenitrile, cis-3-pentenenitrile and 4-pentenenitrile, as well as approximately 10 ppm of 2. -methyl-3-butenonitrile and about 2% by weight of (E) -2-methyl-2-butenonitrile and in minor amounts methylglutardinitrile. Stream 8 can be brought to a process to hydrocyanate 3-pentenenitrile in adiponitrile, as described in Example 2 of the hydroscianation of 3-pentenenitrile according to DE-A-102 004 004 683.

In Example 2, stream 6 is obtained in column K2 and thus also stream 6b without the corresponding separation levels with a considerable proportion of 2-methyl-3-butenonitrile (approximately 1.5% by weight with respect to the nitrile content). of the catalyst stream in Example 2 instead of about 0.1% by weight in Example 1), which leads to a considerable loss of the desired product, forming methylglutarnitrile, when this catalyst is applied after regeneration to hydrocyanate the 3-pentenenitrile in adiponitrile.

Example 3: Example 3 is clarified by means of Figure 4.

In Example 3 a system of catalysts based on nickel (0) complexes with a mixture of ligands is used for the hydrocyanation of 1,3-butadiene. The mixture of ligands for hydrocyanation contains approximately 80 mole percent of tri (m / p-tolyl) phosphite and 20 mole% of the chelate phosphite 2.

In a process step (a) the following currents are brought to a system of three stirring boilers operated continuously and connected successively Rla, Rlb and Rlc with a volume of 10 1 each, which were tempered in 373 K: (1) 5.2 kg / h of liquid cyanhydric acid, unstabilized, released from water by Rla distillation; (2) 4.0 kg / h of liquid cyanhydric acid, destabilized, liberated from the water by distillation of Rlb; (3) 23 kg / h of 1,3-butadiene as stream 2 of the evaporator condenser Bl in process step (b), containing 92% by weight of 1,3-butadiene, 2% by weight of trans- 3-pentenenitrile, 4% by weight of 2-methyl-3-butenonitrile and about 2% by weight of cis-2-butene from Rla; (4) 4.1 kg / hr of Rla nickel (0) catalyst solution, obtained, as described in this example below, as stream 6a from the rectification column K2 in the process step (c); (5) 3.7 kg / h of Rla (0) nickel (0) catalyst solution (CAT), containing in total 45% by weight of pentenenitriles, 1.1% by weight of Ni (0), 38% by weight weight of ligand mixture, as well as about 12% by weight of adiponitrile.

The Rlc reactor is operated as the final reactor with the course from the Rlb reactor to 353 K.

The stream 1 extracted from the Rlc reactor (37 kg / h) contains 7% by weight of 1,3-butadiene, equivalent to a yield of 86% of 1,3-butadiene, as well as a total of 77% by weight of pentenenitriles, 33% by weight of trans-3-pentenenitrile, 41% by weight of 2-methyl-3-butenonitrile, subordinate amounts of cis-3-pentenenitrile, trans-2-pentenenitrile, cis-2-pentenenitrile, 4-pentenenitrile and low amounts of (Z) -2-methyl-2-butenonitrile and (E) -2-methyl-2-butenonitrile, as well as catalyst components, catalyst degradation products and methylglutarnitrile.

The stream 1 is taken in a process step (b) to a stage of the evaporator Bl, which is equipped with a circulating evaporator. The stage of the evaporator Bl is operated in the upper part with a condenser, which is rinsed with condensed material from the return vessel. The stage of the evaporator Bl is operated at an absolute pressure of 0.5 bar of pressure in the upper part, 253 K of condensing temperature and 363 K of outlet temperature in the discharge. 18.5 kg / h of commercially available 1,3-butadiene, containing 0.25% by weight of cis-2-butene, are dosed into the condensate collection tank of the evaporator Bl, which was treated by contact with a molecular sieve, wherein the water content of the 1,3-butadiene applied was reduced to less than 10 ppm by weight of H20.

The stream 2 is withdrawn from the condensate collecting tank of the evaporator stage Bl as the sum of the recirculated and re-dosed 1,3-butadiene and is recycled to the reactor Rla, as described above. 37 kg / h of a stream 3 are obtained from the discharge of the evaporator stage Bl, which in total contains 1% by weight of 1,3-butadiene and cis-2-butene, 82% by weight of pentenenitriles as well as additionally the catalyst components.

Stream 3 is carried in a process step (f) to a reactor R2 tempered at 383 K, designed as a stirring boiler with downstream waiting times, wherein 2-methyl-3-butenonitrile is isomerized in the presence of the nickel catalyst and a Lewis acid in trans-3- pentenonitrile.

A recirculation stream of pentenenitrile 9 (10 kg / h), which is obtained in process step (e) in column 4 as discharge product, contains 60% by weight of 2-methyl- 3-Butenonitrile, in total 10% by weight of trans-3-pentenenitrile with other pentenenitrile isomers, as well as vinylcyclohexene and, in smaller amounts, 1,3-butadiene.

A stream 4 (45 kg / h) is obtained from reactor R2, which contains 62% by weight of trans-3-pentenenitrile and 14% by weight of 2-methyl-3-butenonitrile, equivalent to a yield of 70% by weight of 2-methyl-3-butenonitrile with respect to trans-3-pentenenitrile, as well as the components of the catalyst.

The stream 4 is carried in a process step (c) to a rectification column K2, which is equipped with a molecular evaporator by gravity and condenser and which is operated at an absolute pressure of 50 mbar and 393 K of outlet temperature in the reactor. discharge as a separation column with pieces added to the column that make available 10 levels of separation by distillation.

From the condenser of the rectification column K2, a stream 5 (38 kg / h) is obtained, which contains 91% by weight of pentenenitrile isomers. as well as about 1% by weight of 1,3-butadiene and to a lesser extent (E) -2-methyl-2-butenonitrile, (Z) -2-methyl-2-butenonitrile and vinylcyclohexene.

In the rectification column K2, the catalyst stream 6 (7 kg / h), which contains 1.3% by weight of Ni (0), approximately 20 ppm of 2-methyl-3-butenonitrile, is obtained on the discharge. % by weight of residual pentenonitriles, the remaining catalyst components, adiponitrile and methylglutarnitrile. Stream 6 is partially returned (stream 6a) to reactor RI (4.4 kg / h). The remainder (stream 6b) can be brought to a regeneration (REG), and then, for example, applied in a hydrocyanation of 3-pentenenitrile (corresponds to US 2003/0100442 or to DE-A-103 51 002). Beyond this, the catalyst can be reused in the process for the hydrocyanation of 1,3-butadiene, optionally after separating the zinc chloride.

Stream 5 is carried in a process step (d) to a distillation column K3 which is equipped with a forced circulation evaporator and an upper condenser, as well as with pieces added in the column, which generate 30 theoretical levels of separation. Column K3 is operated at an absolute pressure of 0.12 bar pressure at the top, 334 K temperature at the top and 352 K discharge temperature at the discharge.

In the upper part of column K3, 10 kg / h of a stream 7 are obtained, containing 5% by weight of trans-3-pentenenitrile, 60% by weight of 2-methyl-3-butenonitrile, 4% by weight of (Z) -2-methyl-2-butenonitrile, as well as a total of 4% by weight of 1,3-butadiene and cis-2-butene. The return ratio of column K3 is regulated in such a way that 5% by weight of 3-pentenenitrile is obtained in the upper part.

In the discharge of column K3, 27 kg / h of stream 8 are obtained, which contains in total 98% by weight of trans-3-pentenenitrile, cis-3-pentenenitrile and 4-pentenenitrile, as well as approximately 1000 ppm of 2. methyl-3-butenonitrile and about 2% by weight of (E) -2-methyl-2-butenonitrile.

The stream 7 is carried in a process step (e) to a distillation column K4, which is operated as a reinforcing column and with forced circulation evaporator, upper condenser, return separator, as well as pieces added in the column with structured packing, which generate 15 theoretical levels of separation . Column K4 is operated with an absolute pressure of 380 mbar of pressure in the upper part, 361 K of temperature in the upper part and 365 K of outlet temperature in the discharge.

In column K4, a liquid stream 10 (0.6 kg / h) is obtained in the upper part, which contains in total 4% by weight of 1,3-butadiene and cis-2-butene, 54% by weight of 2 -methyl-3-butenonitrile, 38% by weight of (Z) -2-methyl-2-butenonitrile, as well as 2.5% by weight of vinylcyclohexene. The quantity withdrawn from the stream 10 of the upper part of the column K4 is regulated in such a way that in the upper discharge stream 7 of the column K3 a total of 30% by weight of (Z) -2-methyl-2 is obtained -butenonitrile and vinylcyclohexene. In column K4, a gaseous current (195 norm-l / h), which contains 1,3-butadiene, is obtained in the upper condenser operated as partial condenser.

In column K4, stream 9 (9.4 kg / h) is obtained in the upper part, which contains, in addition to 3-pentenenitriles, essentially 2-methyl-3-butenonitrile that did not react in the isomerization and returns to the isomerization reactor R2 in step (f).

In Example 3, the distillation device Kl of Example 1 is designed as evaporation in a single step Bl, which leads, in comparison with Example 1, to a clearly higher concentration of nitriles, especially 2-methyl-3 - Butenonitrile, in the recirculated butadiene and greater butadiene losses.

Example 4: Example 4 is clarified by means of Figure 5.

In Example 4 it is applied for the hydrocyanation of 1,3-butadiene a system of catalysts based on nickel complexes (0) with a mixture of ligands. The mixture of ligands for hydrocyanation contains approximately 80 mole percent of tri (m / p-tolyl) phosphite and 20 mole% of the chelate phosphonite 1.

In a process step (a) the following current is carried to a system of two stirring boilers continuously operated and connected one after the other Rla and Rlb with a volume of 50 1 each, which are tempered to 363 K: (1) 18 kg / h of liquid hydrocyanic acid, destabilized, liberated from the water by distillation, in equal parts to the reactors Rla and Rlb, (2) 62 kg / h of 1,3-butadiene as stream 2 in the upper part of the evaporator Bl in process step (b), which contains 87% by weight of 1,3-butadiene, 3% by weight of trans-3-pentenenitrile, 6% by weight of 2-methyl-3-butenonitrile and about 2% by weight of cis-2-butene in the Rla reactor, (3) 61 kg / h of a nickel (0) catalyst solution, obtained, as described in this example below, as stream 6a from the stage of the evaporator B2 in the process step (c) in the reactor Rla, (4) 6.7 kg / hr of Rla nickel (0) catalyst solution (CAT), obtained as described in Example 1 of DE-A-102 004 004 683 as evacuation of discharge from the column K4 of process step (4) of Example 2 of this patent application, which contains in total 45% by weight pentenonitriles, 1.1% by weight Ni (0), 38% by weight of a mixture of ligands, as well as about 12% by weight of adiponitrile in the Rla, wherein the 1,3-butadiene stream and the catalyst stream are pre-mixed before coming into contact with hydrocyanic acid, (5) 29 kg / hr of a nitrile recirculation stream 9 obtained as discharge discharge from column K4, as described below in the Example, containing 19% by weight of trans-3-pentenenitrile, 62% by weight of 2-methyl-3-butenonitrile, other nitriles and vinylcyclohexene.

The stream 1 extracted from the Rlb reactor (177 kg / h) contains 11% by weight of 1,3-butadiene, equivalent to a 66% yield of 1,3-butadiene, as well as a total of 64% by weight of pentenenitriles, 32% by weight of trans-3-pentenenitrile, 30% by weight of 2-methyl-3-butenenitrile, subordinate amounts of cis-3-pentenenitrile, trans-2-pentenenitrile, cis-2-pentenenitrile, 4-pentenenitrile. and low amounts of (Z) -2-methyl-2-butenonitrile and (E) -2-methyl-2-butenonitrile, as well as catalyst components and catalyst degradation products.

The stream 1 is carried in a process step (b) to a stage of the evaporator Bl, which is equipped with a molecular evaporator by gravity. The stage of the evaporator Bl is operated in the upper part with a condenser that is rinsed with condensed material from the return vessel. The stage of the evaporator Bl is operated at an absolute pressure of 1.3 bar of pressure in the upper part, 278 K of condensing temperature and 403 K of outlet temperature in the discharge. 37 kg / h of commercially available 1,3-butadiene, containing 0.25% by weight of cis-2-butene, are metered into the condensate collection tank of the evaporator stage Bl, which was treated by contact with a molecular sieve, wherein the water content of the 1,3-butadiene using was reduced to less than 5 ppm by weight and wherein the stabilizer contained in the 1,3-butadiene applied achieves pyrocatechol from ter. -butyl in concentrations within the ppm scale in the condensate collection vessel and the condenser washing circuit.

The stream 2 is withdrawn from the condensate collection tank of the evaporator stage Bl as a sum of recirculated and freshly metered 1,3-butadiene and is recycled to the reactor Rla, as described above.

In the discharge of the evaporator stage Bl, 152 kg / h are obtained from a stream 3, which contains 0.9% by weight of 1,3-butadiene, 16% by weight of 2-methyl-3-butenonitrile, 51% by weight of trans-3-pentenenitrile and other pentenenitrile isomers, as well as additionally the catalyst components. The composition of the discharge of the evaporator stage allows to infer a reaction degree of 50% by weight of 2-methyl-3-butenonitrile in trans-3-pentenenitrile in the evaporator discharge.

Stream 3 is carried in a process step (c) to a stage of the evaporator B2 that is equipped with a molecular evaporator by gravity and condenser and operated at an absolute pressure of 260 mbar and 383 K of exit temperature at the discharge.

A current is obtained from the evaporator stage B2 in gaseous form (83 kg / h), containing 93% by weight of pentenenitrile isomers, approximately 1% by weight of 1,3-butadiene and to a lesser extent (E) -2-methyl-2-butenonitrile, ( Z) -2-methyl-2-butenonitrile and vinylcyclohexene. The stream 5 is taken to the distillation column K3 in process step (d).

In the stage of the evaporator B2, the stream of the catalyst 6 (69 kg / h), which contains 0.6% by weight of Ni (0), 2% by weight of 2-methyl-3-butenonitrile, is obtained at the discharge. 42% by weight of the remaining pentenonitriles. The stream 6 is returned in its vast majority to the reactor Rl (stream 6a) (61.4 kg / h). The remainder (stream 6b) is brought to a regeneration (REG), for example, according to DE-A-103 51 002 and can be applied in the hydrocyanation of 3-pentenenitrile, for example, according to the document DE-A-102 004 004.

The stream 5 is carried in a process step (d) in gaseous form to a distillation column K3, which is equipped with a forced circulation flash evaporator and a top condenser, as well as with a structured packing which generates 30 theoretical levels of separation. Column K3 is operated at an absolute pressure of 80 mbar of pressure in the upper part, 375 K of temperature in the upper part and 343 K of outlet temperature in the discharge.

In the upper part of column K3, 36 kg / h of a stream 7 are obtained, containing 15% by weight of trans-3-pentenenitrile, 64% by weight of 2-methyl-3-butenonitrile, 3% by weight of (Z) -2-methyl-2-butenonitrile, as well as a total of 4% by weight of 1,3-butadiene and cis-2-butene. The return ratio of column K3 is adjusted so that 15% by weight of trans-3-pentenenitrile is obtained in the upper part.

In the discharge of column K3 47 kg / h of stream 8 are obtained, which contains in total 98% by weight of trans-3-pentenenitrile, cis-3-pentenenitrile, trans-2-pentenenitrile, cis-2-pentenenitrile and 4-pentenenitrile, as well as 100 ppm of 2-methyl-3-butenonitrile and about 1% by weight of (E) -2-methyl-2-butenonitrile.

The stream 7 is carried in a process step (e) to a distillation column K4, which is operated as a reinforcing column and is equipped with forced circulation evaporator, upper condenser, return separator, as well as pieces added in the column with structured packing, which generate 45 theoretical levels of separation. The column is operated at an absolute pressure of 320 mbar pressure at the top, 288 K condensation temperature and 363 K discharge temperature at the discharge.

In this column K4 a liquid stream 10 (6.8 kg / h) is obtained in the upper part, which contains in total 10% by weight of 1,3-butadiene and cis-2-butene, 80% by weight of 2 -methyl-3-butenonitrile, 8% by weight of (Z) -2-methyl-2-butenonitrile, as well as 0.5% by weight of vinylcyclohexene. In column K4, a gaseous stream (approximately 250 norm-l / h) containing essentially 1,3-butadiene is obtained in the upper condenser operated as a partial condenser.

In column K4, stream 9 (28.7 kg / h) is obtained at the discharge, which in addition to 3-pentenenitriles contains essentially 2-methyl-3-butenonitrile not reacted in the isomerization and which is returned to the hydrocyanation reactor Rl.

In Example 4 both the distillation device K1 and the distillation device K2 of Example 1 are each carried out as mono-stage evaporators Bl and B2, which, in comparison with Example 1, also leads to considerable losses of butadiene by adapting the conditions in step Bl and the catalyst stream is thermally more charged than in Example 1.

Example 5: Example 5 is clarified by means of Figure 6.

In Example 5 a system of catalysts based on nickel (0) complexes with chelate phosphonite 1 as a ligand is applied for the hydrocyanation of 1,3-butadiene.

In a process step (a) the following currents are carried to a continuously operated boiler Rl with a volume of 30 1, which is tempered to 363 K: (1) 16 kg / h of liquid cyanhydric acid, destabilized, released from water by distillation, (2) 50 kg / h of 1,3-butadiene as stream 2 from the top of the evaporator Bl in process step (b), containing 94% by weight of 1,3-butadiene, 2% by weight of trans-3-pentenenitrile, 4% by weight of 2-methyl-3-butenenitrile and about 1% by weight of cis-2-butene, (3) 10 kg / h of the nickel catalyst solution (0), obtained, as described in this example below, as stream 6a from the stage of the evaporator B2 in the process step (c), which contains in total 42% by weight of pentenenitriles, 23% by weight of ligand, 0.9% by weight of nickel (0), as well as approximately 10% by weight of adiponitrile and approximately 10% by weight of methylglutarnitrile, (4) 4 kg / hr of nickel (0) catalyst solution of Rl (CAT), containing in total 45% by weight of pentenenitriles, 1.5% by weight of Ni (0) and 48% by weight of ligand The stream 1 extracted from the reactor Rl (89 kg / h) contains 17% by weight of 1,3-butadiene, equivalent to a 71% yield of 1,3-butadiene, as well as a total of 73% by weight of pentenenitriles, about 32 wt.% of trahs-3-pentenenitrile, 36 wt.% of 2-methyl-3-butenonitrile, subordinate amounts of "cis-3-pentenenitrile, trans-2-pentenenitrile, cis-2-pentenenitrile, 4- pentenonitrile and low amounts of (Z) -2-methyl-2-butenonitrile and (E) -2-methyl-2-butenonitrile, as well as catalyst components and catalyst degradation products.

The stream 1 is taken in a process step (b) to a distillation column Kl, which is equipped with a molecular evaporator by gravity and which is operated as a separation column with pieces added to the column, which make available 8 levels of separation by distillation. The distillation column Kl is operated at the top with a condenser that is washed with condensed material from the return vessel. The distillation column Kl is operated at an absolute pressure of 1.3 bar pressure at the top, 278 K for the condensing temperature and 403 K for the outlet temperature at the discharge.

In the distillation column Kl, the nitrile recirculation stream 7 of the column K3 is recirculated, as described below.

In the condensate collection vessel of the distillation column Kl, 34 kg / h of commercially available 1,3-butadiene, containing 0.25% by weight of cis-2-butene, are dosed by contact with aluminum oxide, wherein the water content of the 1,3-butadiene used was reduced to less than 10 ppm by weight of H20 and. the content of pyrocatechol stabilizer of ter. -butyl at less than 10 ppm.

The stream 2 is withdrawn from the condensate collecting vessel of the evaporator stage as the sum of recirculated and freshly dosed 1,3-butadiene and is recycled to the reactor Rla, as described above.

In the discharge of the distillation column Kl, 76 kg / h of a stream 3 are obtained, containing 0.8% by weight of 1,3-butadiene, 12% by weight of 2-methyl-3-butenonitrile, 69% by weight of trans-3-pentenenitrile and other pentenenitrile isomers, as well as additionally the catalyst components. The composition of the discharge of the evaporator stage corresponds to a reaction degree of 75% by weight of 2-methyl-3-butenonitrile in trans-3-pentenenitrile in the discharge of the evaporator stage K1.

The stream 3 is carried in a process step (c) to a stage of the evaporator B2, which is equipped with a molecular evaporator by gravity and a condenser and operated at an absolute pressure of 220 mbar and 381 K of outlet temperature at the download.

From the stage of the evaporator B2 a stream 5 is obtained in gaseous form (58 kg / h), which contains 97% by weight of pentenenitrile isomers, as well as approximately 1% by weight of 1,3-butadiene and on a smaller scale ( E) -2-methyl-2-butenonitrile, (Z) -2-methyl-2-butenonitrile and vinylcyclohexene.

In the stage of the evaporator B2, the catalyst stream 6 (17 kg / h), which contains 0.9% by weight of Ni (0), 0.3% by weight of 2-methyl-3-, is obtained at the discharge. butenonitrile and 42% by weight of the remaining pentenonitriles. Stream 6 is mostly carried (stream 6a) to the reactor Rl (10 kg / h). The rest (current 6b) is brought, to a regeneration (REG), for example, according to US 2003/0100442 and can be used after regeneration in a hydrocyanation of 3-pentenenitrile or carried to the process according to the invention in the step of procedure for the hydrocyanation of 1,3-butadiene.

The stream 5 is condensed and brought liquid in a process step (d) to a distillation column K3, which is equipped with a forced circulation evaporator and an upper condenser, as well as with a structured packing, which generate 50 theoretical levels from separation. Column K3 is operated at an absolute pressure of 0.200 bar pressure at the top, 342 K temperature at the top and 366 K discharge temperature at the discharge.

In the upper part of the columns K3 a stream 10 is obtained, containing 10% by weight of 1,3-butadiene, 18% by weight of (Z) -2-methyl-2-butenenitrile, 68% by weight of 2 -methyl-3-butenonitrile, as well as other isomers of pentenonitrile and vinylcyclohexene. The return relation of column K3. it is adjusted in such a way that in the upper drainage stream it contains 18% by weight of (Z) -2-methyl-2-butenonitrile.

In the lateral evacuation in liquid form of the column K3, 8 kg / h of a stream 7 containing 0.5% by weight of trans-3-pentenenitrile, 85% by weight of 2-methyl-3-butenenitrile, are obtained. % by weight of (Z) -2-methyl-2-butenonitrile and 10% by weight of vinylcyclohexene. The stream 7 is taken back to the distillation column Kl in step (b).

In the discharge of column K3 47 kg / h of stream 8 are obtained, which contains in total 98% by weight of trans-3-pentenenitrile, cis-3-pentenenitrile and 4-pentenenitrile, as well as 100 ppm of 2- methyl-3-butenonitrile and about 1% by weight of (E) -2-methyl-2-butenonitrile.

In Example 5 the distillation device Kl of Example 1 is run as a distillation column with a stripping section, the distillation device K2 of Example 1 can be run here as evaporation of a step B2, since the content of 2-methyl- 3-Butenonitrile on admission to B2 is clearly reduced by prior isomerization compared to Examples 1, 2 or 3. Compared to Example 4, the procedure according to Example 5 leads to lower losses of butadiene, but the Catalyst stream is charged, both before and after, more than in Example 1 or 2.

Claims (9)

1. Process for preparing 3-pentenenitrile, characterized by the following process steps: (a) reaction of 1,3-butadiene with hydrocyanic acid with at least one catalyst, obtaining a stream 1 containing 3-pentenenitrile, 2-methyl-3-butenonitrile, the at least one nickel (O) catalyst homogeneously dissolved , which is stabilized with phosphorus ligands, having selected the phosphorus ligands of the group, which comprises: phosphines, phosphites, phosphinites and phosphonites, and 1,3-butadiene, (b) distillation of stream 1 in a column, obtaining a stream 2 rich in 1,3-butadiene as an overhead product and a stream 3 poor in 1,3-butadiene as a discharge product, containing 3-pentenenitrile, at least a catalyst and 2-methyl-3-butenonitrile, "(c) distillation of stream 3 in a column, obtaining a stream 4 as a higher product containing 1,3-butadiene, from a stream 5 in a lateral evacuation of the column containing 3-pentenenitrile and 2-methyl-3. -butenonitrile, and of a stream 6 as a discharge product containing at least one catalyst, (d) distillation of stream 5 by obtaining a stream 7 as an upper product containing 2-methyl-3-butenonitrile, and a stream 8 as a discharge product containing 3-pentenenitrile. being precise, that in the. procedural steps (b) and (c) the discharge temperatures do not exceed 140 ° C and that the sum of the average waiting times in the distillation devices in the process steps (b) and (c) does not exceed 10 hours

2. Process according to claim 1, characterized in that the stream 2 rich in 1,3-butadiene from process step (b) is recirculated at least partially in process step (a).

3. Process according to one of the claims 1 or 2, characterized in that in the process step (c) the stream 6 is obtained at the discharge with a concentration of 2-methyl-3-butenonitrile which is reduced in comparison with the current. , wherein the reduction refers to the ratio of the concentrations of 2-methyl-3-butenonitrile with trans-3-pentenontrile.

4. Process according to one of claims 1 to 3, characterized in that the stream 6 is recirculated from process step (c) at least partially to process step (a).

5. Process according to one of claims 1 to 4, characterized in that the stream 4 of process step (c) is recirculated at least partially to process step (a) and / or (b).

6. Process according to one of claims 1 to 5, characterized in that the stream 5 in the lateral evacuation in process step (c) is extracted in gaseous form.

7. Process according to one of claims 1 to 6, characterized in that the stream 7 of process step (d) is recirculated at least partially to process step (a) and / or to process step (b).

8. Process according to one of claims 1 to 7, characterized in that in the process step (c) there are 1 to 50 levels of separation by distillation between the position of the lateral evacuation and the discharge.

9. Process according to one of claims 1 to 8, characterized in that the proportion of 2-methyl-3-butenonitrile in the catalyst stream 6 obtained in process step (c) is from 0 to 5% by weight. Summary A process for preparing 3-pentenenitrile, characterized by the following process steps, is described: (a) reaction of 1,3-butadiene with hydrocyanic acid with at least one catalyst, obtaining a stream 1 containing 3-pentenenitrile, 2-methyl-3-butenonitrile, at least one catalyst and 1,3-butadiene, (b) distillation of stream 1. in a column, obtaining a stream 2 rich in 1, 3-butadiene 2 as an overhead product and a stream 3 poor in 1,3-butadiene as a discharge product, containing 3-pentenenitrile, at least one catalyst and 2-methyl-3-butenonitrile, (c) distillation of stream 3 in a column, obtaining a stream 4 as a higher product containing 1,3-butadiene, from a stream 5 in a lateral evacuation of the column containing 3-pentenenitrile and 2-methyl-3- butenonitrile, and a stream 6 as a discharge product containing at least one catalyst, (d) distillation of stream 5 by obtaining a stream 7 as the top product, which contains 2-methyl-3-butenonitrile, and a stream 8 as a discharge product containing 3-pentenontrile. • 10 fifteen twenty 25 Summary A process for preparing 3-pentenenitrile, characterized by the following process steps, is described: (a) reaction of 1,3-butadiene with hydrocyanic acid with at least one catalyst, obtaining a stream 1 containing 3-pentenenitrile, 2-methyl-3-butenenitrile, at least one catalyst and 1,3-butadiene, (b) distillation of stream 1 in a column, obtaining a stream 2 rich in 1,3-butadiene 2 as an overhead product and a stream 3 poor in 1,3-butadiene as a discharge product, containing 3-pentenenitrile, minus a catalyst and 2-methyl-3-butenonitrile, (c) distillation of stream 3 in a column, obtaining a stream 4 as a higher product containing 1,3-butadiene, from a stream 5 in a lateral evacuation of the column containing 3-pentenenitrile and 2-methyl-3 - butenonitrile, and a stream 6 as a discharge product containing at least one catalyst, (d) distillation of stream 5 by obtaining a stream 7 as the top product, which contains 2-methyl-3-butenonitrile, and a stream 8 as a discharge product containing 3-pentenontrile.