WO1996003363A1

WO1996003363A1 - Process for the hydroformylation of olefinically unsaturated compounds

Info

Publication number: WO1996003363A1
Application number: PCT/EP1995/002910
Authority: WO
Inventors: Helmut Bahrmann; Christian W. Kohlpaintner; Wolfgang A. Herrmann; Rochus Schmid; Guido Albanese
Original assignee: Hoechst Aktiengesellschaft
Priority date: 1994-07-27
Filing date: 1995-07-22
Publication date: 1996-02-08
Also published as: DE4426577C2; DE4426577A1; ZA956232B

Abstract

Olefines are hydroformylated in the presence of rhodium-diphosphine complex compounds as catalysts. The diphosphines have a (Casey) angle of nip of 100 to 160° and a (Tolman) approach angle of 120 to 240 °C and the isomer energy difference is at least 2 kcal/mol.

Description

Process for Hvdroformylation of olefinically unsaturated

links

The invention relates to a process for the hydroformylation of olefinically unsaturated compounds in the presence of rhodium complex compounds as catalysts which contain diphosphines as complex ligands.

It is known to produce aldehydes and alcohols containing one carbon atom more than the starting olefin by reacting olefins with carbon monoxide and hydrogen (hydroformylation). The reaction is catalyzed by hydridometal carbonyls, preferably those of the metals of group VIII of the periodic table. In addition to cobalt, the classic catalyst metal, catalysts based on rhodium have recently been increasingly used. In contrast to cobalt, rhodium allows the reaction to be carried out at low pressure; moreover, when terminal olefins are used, straight-chain n-aldehydes are preferably formed and iso-aldehydes are formed only in subordinate malts. Finally, the hydrogenation of the olefinic compounds to saturated hydrocarbons in the presence of rhodium catalysts is also significantly less than when using cobalt catalysts.

In the processes introduced in industry, the rhodium catalyst is used in the form of modified hydridorhodium carbonyls which contain additional ligands, in particular tertiary, organic phosphines or phosphites. The ligands are usually present in excess in relation to the metal atom, so that the catalyst system consists of complex compound and free ligand. The

SPARE BLADE RULE 26 Use of the rhodium catalysts described makes it possible to carry out the hydroformylation reaction at pressures below 30 MPa.

The hydroformylation of olefinically unsaturated compounds under the catalytic action of rhodium-phosphine complex compounds is essentially realized in two variants. In one embodiment, the catalyst is homogeneously dissolved in the reaction mixture, in the other it, when dissolved in water, forms its own phase. Both processes have been described many times in the literature, for example by B. Cornils in New Syntheses with Carbon Monoxide Berlin, Heidelberg, New York 1980, also in DE-C-26 27 354 and EP-B-01 03 810. The reaction has different characteristics among others Influence on the level of sales of raw materials and the formation of by-products. In general, the heterogeneous process achieves better conversions with higher selectivity compared to the homogeneous process. A particular advantage of the implementation in the system with a separate catalyst phase is the problem-free separation of the catalyst. It is done by simply separating the aqueous and organic phases, i.e. without distillation and thus without thermal process steps. In contrast, in homogeneously catalyzed processes, the reaction product has to be distilled off from the catalyst, a measure which is often associated with losses in yield due to the thermal sensitivity of the reaction products.

The most commonly used phosphine ligands are triphenylphosphine in the homogeneously catalyzed process and trisodium tri (m-sulfophenyl) phosphine in the heterogeneous catalyst system. Further developments of both processes strive for technical and economic reasons, among others. an increase in the activity and life of the catalytic converter

SPARE BLADE (RULE 26) and an improvement in their selectivity with regard to the formation of unbranched aldehydes. Economic considerations are also decisive for working towards a significant reduction in the phosphine / rhodium ratio. Investigations in this direction concern, inter alia, the replacement of the water-insoluble or soluble phosphines known as complex ligands by modified or new representatives of this class of compounds.

It is therefore of great interest to improve the hydroformylation process as outlined above, i.e. through targeted selection of suitable phosphine ligands to develop catalysts which, with the lowest possible ligand / rhodium ratio, exceed the activity and selectivity of known catalysts.

One step in this direction is the replacement of monophosphines as complex ligands by diphosphines, in particular by diphosphines, which react with the central atom of the complex compound to form chelates. For example, described in EP 0 311 619 B1 chelate ligands for catalysts which are used in the low-pressure hydroformylation of olefins and in the molecule modified 3 -> 01efins by heteroatom substitution. These are diphosphines which are derived from biphenyl, phenylnaphthalene and binaphthalene as the base body.

Casey et al. report in J.Am.Chem.Soc. 1992, 114, 5535 ff on the relationship between the size of the natural bite angle (natural bite angle) of chelating diphosphines and their regioselectivity with regard to the formation of straight-chain aldehydes in the hydroformylation of 1-hexene in the presence of a rhodium catalyst. In addition to flexible adaptation to the desired selectivity - the preferred formation of branched products can also be the goal of the hydroformylation reaction in special cases - industrially used catalysts must also meet further requirements. Among them, the demands for high activity, ie the amount of aldehyde, which is formed for each amount of catalyst and unit of time, and for long-term stability are of outstanding importance. In addition, the aim is to achieve the desired results with the lowest possible ligand / rhodium ratio.

The object of the invention is to improve the hydroformylation process by selecting suitable diphosphine ligands as constituents of the catalyst.

The invention consists in a process for the hydroformylation of olefinically unsaturated compounds at temperatures from 20 to 150 ° C. and pressures from 0.1 to 20 MPa in the presence of diphosphines in rhodium compounds containing complex bonds. It is characterized in that the diphosphines have a bite angle (according to Casey) of 100 to 160 ° and a cone angle (according to Tolman) from 120 to 240 ° and the isomer energy difference Δ E is at least 2.0 kcal / mol.

The new process allows the selection of diphosphines as a catalyst component, among others. with the aim of controlling the catalytic activity and, when using terminal olefins, the ratio of n- and iso-aldehyde in the reaction product.

A key feature of the new process is the use of diphosphines, whose natural bite angle is 100 is up to 160 °. The natural bite angle is a calculation that describes the space requirement of the ligand. Casey et al. define it as the preferred chelation angle, ie the phosphorus-metal-phosphorus angle (PMP angle with M = rhodium), which occurs when the bidentate phosphine is chelated in coordination with a rhodium atom that is not linked to any other ligand . The natural bite angle results from the graphical representation of the energy content of the chelate complex compared to the associated bite angle. The natural bite angle corresponds to the bite angle with the lowest energy content of the complex (minimum energy; see Casey et al., Isr.J.Chem., 30 (4), 299 ff (1990). The larger the bite angle of the ligand, the greater is its space requirement and the higher is the n / iso ratio which can be achieved when it is used as a component of hydroformylation catalysts, preferably diphosphines with a bite angle of 120 to 150 ^β C.

Another measure of the space requirement of phosphine ligands is the cone angle “θ” according to Tolman (CA. Tolman, Chem. Rev. 1977, 77, 313 ff). It is defined as the opening angle of a cone, the tip of which is 2.28 8 from the phosphorus atom and whose surface lines are described by the tangents to the van der Waals radii of the substituents on the phosphorus atom. This definition can also be applied to diphosphines if they attack the metal like a chelate. In this case, the cone angle of the diphosphine is made up of the half-angle of neither of the two PM fragments and the PMP angle. The description of the determination method is published (Tolman et al., J.Am.Chem.Soc. 1974, 96, 53-60 ⁾ . According to the invention, the cone angle is 120 to 240 °, in particular 180 to 210 °. Diphosphines with a large cone angle lead to the preferred formation of unbranched products as catalyst components for steric reasons. Conversely, phosphines with a small space requirement increasingly result in iso compounds. Since the PMP angle is included in the calculation of the cone angle for diphosphines, the cone and bite angles have a direct influence on the space requirement of these ligands. Both angles are purely geometrical sizes and are therefore accessible for arithmetic treatment.

Another characteristic of those used according to the invention

Diphosphine is the energy difference Δ. E = Ei.so - En of the two isomeric intermediates I and II, which are formed by the insertion reaction of the olefin into the catalytically active rhodium hydridocarbonyl complex. This is the first, product-determining step of hydroformylation (see e.g. Evans et al. J. Chem.Soc [AI 1968, 3133).

II

By determining the bite angle according to Casey, the space requirement of the phosphine ligands is determined on the assumption that the metal atom is not connected to any other ligand. The calculation of the energy difference of the isomers according to formulas I and II also takes into account the influence of other ligands that are active metal complex compound are bound. As a result, the space requirement of the diphosphines can be determined much more precisely and the catalytic properties of the rhodium / diphosphine complex compounds can be adjusted much more precisely to the desired result. As a result, the computational simulation moves much closer to the real conditions during the catalytic cycle. According to the invention, the isomer energy difference is at least 2 kcal / mol, preferably at least 2.5 kcal / mol.

The energy difference between the isomeric intermediate stages I (Ei.so) and II (En) is calculated using the Discover 2.8 program (Biosy Technologies, San Diego 1992) by completely minimizing the energy calculated by the "cff91" force field. The force field "cff91" integrated in the program is adapted to the problem by introducing additional parameters. The following additions are to be added to the parameter list:

IBIOSYM forcefield

#version cff91-p.frc 2.1 09-Dec-93

.Version cff91-rh.frc 2.2 15-Jun-94

#version cff91-rh.frc 2. 3 16-Jun-94

#version cff91-rh.frc 2.4 17-Jun-94

#atom_types cff91

> Atom type definitions for any variant of cff91

> Masses from CRC 1973/74 pages B-250

Ver Ref Type Mass EleConnect Comment ment ion

2.2 6 RhC 1.0 Rh 4 Rhodium center 2.4 8 cCO 12.0 C 2 carbon in metal carbonyl

2.4 oCO 15.99940 oxygen in metal carbonyl

.equivalence cff91

Equivalences

Ver Ref Type NonB Bond Angle Torsion OOP

2.2 6 RhC RhC RhC RhC RhC RhC

2.4 8 cCO c 'cCO cCO cCO

2.4 8 oCO o 'oCO oCO oCO

#quartic_bond cff91

> E = K2 * (R-RO) ^* 2 + K3 * (R-RO) "3 + K4 * (R-RO) ^* 4

Ver Ref I J RO K2 K3 K4

2.1 5 P c 1.8400 210.0000 0.0000 0.0000

2.1 5 P cp 1.8200 210.0000 0.0000 0.0000

2.2 6 RhC P 2.3 1000.0 0.0000 0.0000

2.3 7 RhC c 2.1 1000.0 0.0 0.0

2.4 8 cCO oCO 1.18 820.7018 -1875.1000 2303.7600

2.4 8 RhC cCO 1.9 1000.0 0.0 0.0

. torsion 3 cff91

> E = SUM (n = l, 3) (V (n) * [l + cos (n * Phi-PhiO (n))]}

Ver Ref I J K L VI PhiO V2 PhiO

2.1 5 c P cp cp 0.0000 0.0 0.0000 0.0

2.1 5 cp P cp cp 0.0000 0.0 0.0000 0.0

2.1 5 h c P c 0.0000 0.0 0.0000 0.0

2.1 5 c P c c -0.0750 0.0 0.0000 0.0

2.1 5 c P c cp -0.0750 0.0 0.0000 0.0

2.1 5 cp P c h 0.0250 0.0 0.0000 0.0

2.1 5 cp P c c -0.0250 0.0 0.0500 0.0

2.1 5 cp P c cp -0.0250 0.0 0.0500 0.0

2.1 5 cp cp cp P 0.0000 0.0 4.4000 0.0

2.1 5 h cp cp P 0.0000 0.0 1.5600 0.0

2.1 5 cp cp c P 0.1223 0.0 0.0514 0.0

2.1 5 h c c P 0.0000 0.0 0.0316 0.0

2.1 5 c c c P 0.1223 0.0 0.0514 0.0

2.1 5 P c c P 0.1223 0.0 0.0514 0.0

2.2 6 cp P RhC P 0.0000 0.0 0.0000 0.0

2.2 6 c P RhC P 0.0000 0.0 0.0000 0.0

2.2 6 cp cp P RhC 0.0000 0.0 0.0000 0.0

2.2 6 cp c P RhC 0.0000 0.0 0.0000 0.0

2.2 6 c c P RhC 0.0000 0.0 0.0000 0.0

2.2 6 h c P RhC 0.0000 0.0 0.0000 0.0

2.3 7 h c c RhC 0.0000 0.0 0.0000 0.0

2.3 7 c c c RhC 0.0000 0.0 0.0000 0.0

2.3 7 c c RhC P 0.0000 0.0 0.0000 0.0

2.3 7 h c RhC P 0.0000 0.0 0.0000 0.0

2.3 7 c P RhC c 0.0000 0.0 0.0000 0.0

2.3 7 cp P RhC c 0.0000 0.0 0.0000 0.0

2.4 8 oCO cCO RhC c 0.0000 0.0 0.0000 0.0

2.4 8 oCO cCO RhC P 0.0000 0.0 0.0000 0.0

2.4 8 cCO RhC P c 0.0000 0.0 0.0000 0.0

2.4 8 cCO RhC P cp 0.0000 0.0 0.0000 0.0

2.4 8 cCO RhC c c 0.0000 0.0 0.0000 0.0

2.4 8 cCO RhC c h 0.0000 0.0 0.0000 0.0

.Wilson out of plane cff91> E = K * (Chi-Chiθr2

Ver Ref I J K L K ChiO

2.1 cp cp cp 8.0000 0.0 .nonbond (9-6) cff91

> E = eps ⁽ ij ^{) [} 2 ⁽ r ⁽ ij ⁾ * / r ⁽ ij ⁾⁾ ** 9-3 ⁽ r (ij) * / r (ij)) ** 61

> where r (ij ⁾ = I (r (i ⁾ ** 6 + r (j) ** 6)) / 21 ** (l / 6)>

> eps (ij) = 2 sqrt (eps (i) * eps (j)) *

> r ⁽ i ^{) Λ} 3 * r ⁽ j ^{) *} 3 / Ir (i ^{) Λ} 6 + r (j) -6]

Ver Ref eps

2.1 5 P 4.2000 0.1500

2.2 6 RhC 0.0 0.0

#reference 5 parameters for phosphane treference 6

Rhodium (RhC) Parameters

.reference 7 parameters for c at RhC .reference 8

Parameters for cCO and oCO (carbonyl) on RhC

The energy content is calculated as follows:

- The starting structures of both molecules are in accordance with formulas I and II with the one to be investigated

Diphosphine built up as a ligand. The rhodium atom at the origin of the Cartesian coordinate system and the ligand atoms directly linked to the rhodium (both phosphorus atoms, carbonyl and alkyl carbon) are in the xy plane.

- Exactly 0.05 nm above and below the rhodium atom, two additional atoms are built in as pseudoligands on the z-axis, which are not connected to any other atom (the Cartesian coordinates in nm are 10/0 / 0.051 and I0 / 0 / -0.05]. - The cff91 atom types are assigned to all atoms of the ligand according to the standard rules of the cff91 force field.

- All other atoms of the molecules are assigned atom types according to the following table

Description of the atom atom type

Rhodium atom RhC

Phosphorus atom in the phosphine p

Carbon in carbonyl cCO oxygen in carbonyl oCO

Carbon in the alkyl ligand c

Hydrogen in the alkyl ligand h

Pseudo ligands h

- The two pseudo ligands and the rhodium atom are fixed in their positions.

- The geometry of the system is varied by standard algorithms until the minimum energy of the system is reached. All possible conformations of the ligand must also be taken into account.

This energ ³ ie Unlock ^c directing Ei.so or En. The difference between these values is the Isomerenenergiedifferenz.

Diphosphine ligands whose terminal bridging carbon atoms (these are the carbon atoms at the two ends of the carbon chain which are bonded to one of the phosphorus atoms of the diphosphine in each case) are at least 0.33 nm apart. This distance is characterized by bridges made of carbon atoms that are linked together by single bonds Entropy reasons not reached (no chelating coordination). In contrast, it is possible to set such distances with carbon atom bridges in which the mobility of the carbon atoms is restricted by multiple bonds between them. Examples of this are the 2,2'-dimethylbiaryl systems, which lead to a distance of the terminal bridging carbon atoms of more than 0.4 nm.

The diphosphines used as catalyst components in the new process give the catalysts remarkably high flexibility and effectiveness. The formation of normal aldehydes can be increased further compared to known processes, but it is also possible to adapt the ratio of n- and iso-compound in the reaction product to the respective requirements. The discharge of noble metal and phosphine with the reaction product is further reduced compared to the prior art. In addition, these results are achieved with catalysts which have a significantly lower ligand / rhodium ratio than those previously used.

The new process can be carried out with catalysts homogeneously dissolved in the reaction medium. However, complex compounds dissolved in water, which form a separate catalyst phase, can be used with equally good success, a possibility which is surprising because by introducing hydrophilic residues such as the sulfonate - (- SO..H) or the carboxylate - (- COOH ) Group in the diphosphine molecule compared to the unsubstituted molecule, both the steric and the electronic conditions can be changed significantly.

According to the new process, rhodium is used either as a metal or as a compound. In metallic Form it is used in the form of finely divided particles or in a thin layer on a support such as activated carbon, calcium carbonate, aluminum silicate, alumina. The type of rhodium compound depends on whether the reactants are reacted in a homogeneous or heterogeneous liquid phase. Substances which are soluble from the start in the organic phase or in water or which become soluble under the reaction conditions are therefore suitable.

The various rhodium oxides, salts of inorganic hydro- or oxygen acids, and salts of aliphatic mono- or polycarboxylic acids are suitable. Examples of rhodium salts are rhodium nitrate, rhodium sulfate, rhodium acetate, rhodium 2-ethylhexanoate, rhodium malonate. Rhodium halogen compounds, on the other hand, are less useful because of the corrosive behavior of the halide ions. Rhodium carbonyl compounds such as Rh ₃ (CO), ₂ or Rhg (CO) .g or complex salts of rhodium, for example cycloocadienylrhodium compounds, can also be used. Rhodium oxide and in particular rhodium acetate and are preferred

Rhodium 2-ethylhexanoate. Under the conditions of the hydroformylation reaction, lipophilic or hydrophilic rhodium complex compounds are formed which contain carbon monoxide and the diphosphine which is soluble in organic medium or in water as ligands.

It is not necessary to use the diphosphines as uniform compounds. For example, Mixtures of different diphosphines or, in the case of water-soluble ligands, diphosphines of different sulfonation or carboxylation stages can be used.

It has been proven that rhodium and diphosphine are not in a stoichiometric ratio, i.e. according to the to use chemical composition of the rhodium complex compound, which forms in the course of the hydroformylation reaction, but to use the diphosphine in excess. The ratio of rhodium and diphosphine can be varied within wide limits and about 1 to 130 mol of diphosphine can be used per mole of rhodium. A ratio of rhodium to diphosphine in the range from 1: 2 to 1:25 and in particular 1: 2 to 1:10 mol is preferred.

The solution of the catalyst in the organic solvent or in water is prepared from the components either in the hydroformylation reactor or beforehand in a separate device and then fed to the hydroformylation reactor.

The concentration of the rhodium in the reaction mixture or in the aqueous catalyst solution is 20 to 1000 ppm by weight (based on the solution), preferably 100 to 600 ppm by weight and in particular 200 to 400 ppm by weight.

The reaction of the olefin with carbon monoxide and hydrogen takes place at pressures of approximately 0.1 to approximately 30 MPa, preferably 1 to 12 MPa and in particular 3 to 7 MPa. The composition of the synthesis gas, i.e. the volume ratio of carbon monoxide and hydrogen can extend over wide ranges and e.g. can be varied between 1:10 and 10: 1. Generally you bet

Gas mixtures in which the volume ratio of carbon monoxide and hydrogen is approximately 1: 1 or deviates only slightly from this value in one or the other direction.

The reaction temperature is between about 20 to 150 ° C, preferably 80 to 140 C ^β us in particular 100 to 125 ° C.

• • • The reaction partners present in the liquid and gaseous phase are converted in conventional reactors. The course of the reaction in the liquid two-phase system is significantly influenced by the fact that the aqueous catalyst solution must be saturated with the liquid or gaseous, hydrophobic olefin and the synthesis gas. It is therefore necessary to create the largest possible contact area between the phases. It has proven useful to stir the liquid reactor contents - catalyst solution, optionally liquid olefin and reaction product - intensively and to feed the gaseous reactants - synthesis gas and optionally olefin - via distribution devices to the liquid phase. It has proven very useful to keep the proportion of the organic phase in the reaction mixture low. Surprisingly, the organic phase does not contribute to the solubility of the reactants in the aqueous phase and it is avoided that the reaction product undergoes undesired side reactions which cannot be ruled out with increasing product residence time in the reactor. A volume ratio of aqueous to organic phase is accordingly set from 1: 1 to 100: 1, preferably 10: 1 to 100: 1. For this purpose, a corresponding part of the reaction mixture can be continuously removed from the reactor, aqueous and organic phases separated from one another and the aqueous phase returned to the reactor. The reaction can be carried out batchwise or, preferably, continuously.

The process according to the invention is successfully applicable to the conversion of monoolefins, non-conjugated polyolefins, cyclic olefins and derivatives of these unsaturated compounds. Regarding the molecular large ones, the olefins used are not subject to any restrictions, the procedure has proven successful for compounds having 2 to 40 carbon atoms. The olefinically unsaturated compounds can be straight-chain or branched, the double bonds can be terminal or internal. Examples of olefins that can be used in the new process are ethylene, propylene, butene-1, butene-2, pentene-1, 2-methylbutene-1, hexene-1, hexene-2, heptene-1, octene-1 , Octen-3, 3-ethylhexene-1, decene-1, undecene-3, 4,4-dimethylnone-1, dicyclopentadiene, vinylcyclohexene, cyclooctadiene, styrene. Derivatives of the olefins mentioned which can be hydroformylated according to the claimed procedure are, for example, alcohols, aldehydes, carboxylic acids, esters, nitriles and halogen compounds, allyl alcohol, acrolein, methacrolein, crotonaldehyde, methyl acrylate, ethyl crotonate, diethyl fumarate , Diethyl maleate, acrylonitrile. The process for the hydroformylation of olefins and olefin derivatives having 2 to 20 and in particular 2 to 8 carbon atoms is used with particular success.

Claims

claims

1.) Process for the hydroformylation of olefinically unsaturated compounds at temperatures from 20 to 150 ° C. and pressures from 0.1 to 20 MPa in the presence of diphosphines in rhodium compounds containing complex bonds, characterized in that the diphosphines have a bite angle (according to Casey) from 100 to 160 ° and a cone angle (according to Tolman) from 120 to 240 ° and the isomer energy difference Λ E is at least 2.0 kcal / mol.

2.) Method according to claim 1, characterized in that the bite angle is 120 to 150 °.

3.) Method according to claim 1 or 2, characterized gekenn¬ characterized in that the cone angle is 130 to 210 °.

4.) Method according to one or more of claims 1 to 3, characterized in that the isomer energy difference E is at least 2.5 kcal / mol.

5.) Method according to one or more of claims 1 to 4, characterized in that the distance between the terminal bridging carbon atoms in the phosphine is at least 0.33 nm.

6.) Method according to claim 5, characterized in that the distance between the terminal bridging carbon atoms in the phosphine is more than 0.4 nm.

7.) Method according to one or more of claims 1 to 6, characterized in that the diphosphines are soluble in water.

8.) Process according to claim 7, characterized in that the water-soluble diphosphines contain sulfonate - (- SO-H) - or carboxylate - (- COOH) groups.