Method for producing polycyclic aliphatic dialdehyde

Abstract

The present invention relates to a process for producing polycyclic aliphatic dialdehydes by hydroformylating polycyclic aliphatic diolefins in the presence of synthesis gas over an organophosphorus ligand-modified metal catalyst system having a transition metal of the 8th to 10th subgroups, wherein the hydroformylation is carried out in a homogeneous liquid reaction phase using a water-soluble diphosphine- or triarylphosphine complex catalyst under a pressure of 0.5 MPa or more and 10 MPa or less and at a temperature of 70° C. or more and 150° C. or less, wherein the homogeneous liquid phase comprises at least one non-aqueous solvent, diolefins and / or their mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution, and the quantitative ratio of these components in the solution is controlled so that a single-phase solution exists under the reaction conditions.

Description

[Technical Field]

[0001] The present invention relates to a process for producing polycyclic aliphatic dialdehydes by hydroformylating polycyclic aliphatic diolefins over an organophosphorus ligand-modified metal catalyst system having a transition metal of subgroups 8 to 10 in the presence of synthesis gas, wherein the hydroformylation is carried out in a homogeneous liquid reaction phase using a water-soluble diphosphine- or triarylphosphine complex catalyst under a pressure of 0.5 MPa or more and 10 MPa or less and at a temperature of 70°C or more and 150°C or less, wherein the homogeneous liquid phase comprises at least one non-aqueous solvent, olefins and / or their mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution, and the mass ratio of these components in the solution is controlled such that a single-phase solution exists under the reaction conditions. [Background technology]

[0002] Due to their special geometry, unsaturated cyclic hydrocarbons with at least two isolated double bonds in the ring structure are valuable chemical raw materials that can be converted into functionally exceptional compounds. The cyclic hydrocarbon skeleton confers special properties to these molecules, which are reflected not only in specific conversion conditions but also in specific application functions. Some important representatives of this class of compounds are, for example, cyclopentadiene, as well as dicyclopentadiene (DCP, designated by IUPAC as tricyclo[5.2.1.0]), which can be obtained by dimerization of cyclopentadiene and can be produced on a large scale. 2,6 ]deca-3,8-diene).

[0003] Further functionalization of these compounds by conversion of one or more double bonds to other functional groups is also known and described in the literature. For example, these double bonds can be converted to aldehydes by catalytic addition of carbon monoxide and hydrogen within the context of hydroformylation. While this conversion was once carried out almost exclusively using cobalt catalysts, modern methods are carried out using metal catalyst systems based on transition metals of subgroups 8 to 10. Depending on the specifically selected reaction conditions, these catalysts are used alone or together with complexing ligands, such as organic phosphines or phosphate esters. According to the consensus of those skilled in the art, under the reaction conditions, for example, in the case of rhodium, the general formula H[Rh(CO) 4-X L X ] (L represents an organic ligand, and x is 0 or an integer from 1 to 3). In the case of DCP conversion, either mono- or dialdehydes are obtained as conversion products, and the latter can be converted by a final hydrogenation step to the economically valuable diol tricyclo[5.2.1.0 2,6 ] can be further converted to decanedimethanol.

[0004] Several hydroformylation processes for the conversion of cyclic olefins to the corresponding aldehydes and optionally further conversion of the aldehydes to the corresponding alcohols are also described in the patent literature.

[0005] For example, DE 102006004318 A1 (Patent Document 1) discloses a method for producing 3(4),7(8)-dihydroxymethyl-bicyclo[4.3.0]nonane by hydroformylation using bicyclo[4.3.0]nona-3,7-diene and subsequent hydrogenation, in which bicyclo[4.3.0]nona-3,7-diene is reacted with synthesis gas in a homogeneous organic phase in the presence of a transition metal compound of Group VIII of the Periodic Table containing an organophosphorus compound in a complexed state and an excess of the organophosphorus compound at a temperature of 70 to 160°C and a pressure of 5 to 35 MPa, and the 3(4),7(8)-bisformyl-bicyclo[4.3.0]nonane thus obtained is then hydrogenated to give 3(4),7(8)-dihydroxymethyl-bicyclo[4.3.0]nonane.

[0006] EP1529771A1 (Patent Document 2) also discloses that dicyclopentadiene is hydroformylated with synthesis gas in a heterogeneous reaction system using an aqueous solution of a transition metal compound of Group VIII of the periodic table containing a water-soluble organophosphorus(III) compound in a complex bonded state at a temperature of 70 to 150°C and a pressure of 0.5 to 10 MPa to obtain 8(9)-formyl-tricyclo[5.2.1.0]. 2.6 ] discloses a method for producing dec-3-ene, which utilizes special sulfonated triarylphosphines as water-soluble organophosphorus(III) compounds.

[0007] Furthermore, WO2004024661A1 (Patent Document 3) describes a method for catalytic hydroformylation of olefinically unsaturated compounds having 3 to 24 carbon atoms, in which an unmodified catalyst having at least one metal from Groups 8 to 10 of the Periodic Table of Elements is used as the catalyst, and the hydroformylation is carried out according to the following formula:

[0008] [ka] [R1, R 2 , R 3 , R 4are the same or different and each represents H, a substituted or unsubstituted aliphatic, alicyclic, aromatic, aliphatic-alicyclic, aliphatic-aromatic, or alicyclic-aromatic hydrocarbon residue having 1 to 27 carbon atoms, n is 0 to 5, X is a divalent substituted or unsubstituted aliphatic, alicyclic, aromatic, aliphatic-alicyclic, or aliphatic-aromatic hydrocarbon residue having 1 to 27 carbon atoms. in the presence of a cyclic carbonate, the proportion of which is at least 1% by weight of the reaction mixture.

[0009] Such solutions known from the prior art may still leave room for improvement, especially with regard to the conversion efficiency and the lifetime of the catalytic materials used. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] DE102006004318A1 [Patent Document 2] EP1529771A1 [Patent Document 3] WO2004024661A1 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the object of the present invention is to at least partially overcome the drawbacks known from the prior art.The object of the present invention is to provide a method that provides high conversion and selectivity under very mild reaction conditions, particularly with low catalyst concentrations and long reaction times. [Means for solving the problem]

[0012] The solution to the above problem is achieved by the features of the independent method claims. Preferred embodiments of the invention are set out in the subclaims, the description and the drawings, wherein further features set out or shown in the subclaims or the description or drawings may, alone or in any combination, constitute the subject matter of the invention, unless the context clearly indicates otherwise.

[0013] According to the present invention, the above-mentioned object is achieved by a process for producing polycyclic aliphatic dialdehydes by hydroformylating polycyclic aliphatic diolefins in the presence of synthesis gas over an organophosphorus ligand-modified metal catalyst system having a transition metal of subgroups 8 to 10, wherein the hydroformylation is carried out in a homogeneous liquid reaction phase using a water-soluble diphosphine or triarylphosphine complex catalyst at a pressure of 0.5 to 10 MPa and a temperature of 70 to 150°C, wherein the homogeneous liquid phase comprises at least one non-aqueous solvent, diolefins and / or their mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution, and the mass ratio of these components in the solution is controlled so that a single-phase solution exists under the reaction conditions.

[0014] It has surprisingly been found that the hydroformylation of polycyclic dienes to the corresponding dialdehydes can be carried out very efficiently under mild process conditions using exceptionally stable and selective catalyst systems, even over relatively long process times. These advantages are due to the fact that the conversion is carried out in a homogeneous liquid phase containing both organic and aqueous components. By adjusting the amounts of at least the components indicated above, i.e., catalyst solution, raw material or intermediate or final product derived therefrom, and solvent, the entire solution can be maintained in the single-phase region of the phase diagram, and, surprisingly, the water-soluble catalyst is uniformly distributed throughout the solution and can be fully contacted with the raw material and synthesis gas without hindrance. Within the homogeneous single-phase region, there is not two separate phases, such as an aqueous phase containing the catalyst solution and a separate organic phase containing the resulting product or intermediate, but rather a single homogeneously mixed aqueous / organic phase. By controlling the amounts of the different, at least partially miscible, individual components, the entire conversion can be reliably carried out in a single phase, and surprisingly, the conversion does not stop at the monoaldehyde stage but proceeds to the dialdehyde with high selectivity and rapid reaction rate. This result is surprising because water-soluble catalysts only result in a single conversion in a "two-phase" reaction environment, and the reaction "stops" at the monoaldehyde stage. In contrast, when considering conversion in a purely organic phase, i.e., without the addition of aqueous or water-soluble components, high conversion rates with good selectivity can result. In summary, from both of these different prior art processes, it can be inferred that conversion over a catalyst in the presence of an inflow of gaseous reactants and aqueous additives, or the use of an entirely water-soluble catalyst, leads to rather poor synthesis. The latter is particularly true for the conversion of cyclic dienes with rigid ring structures, which inherently make efficient addition over the catalyst system difficult. However, such degradation surprisingly does not occur even with the difficult feedstocks considered here. Furthermore, the combination of a water-soluble catalyst with a homogeneous organic / aqueous phase appears to contribute to exceptional protection of the catalyst system in the conversion, so that it is advantageously possible to work with very small amounts of catalyst, which also have a long life.

[0015] The process according to the present invention is a method for producing polycyclic aliphatic dialdehydes. Polycyclic aliphatic dialdehydes have at least two non-aromatic ring structures and, as a whole, at least two aldehyde groups, with at least one of these aldehyde groups being directly located on the ring structure. Preferably, both aldehyde groups can be directly bonded to the ring structure. The entire aliphatic ring structure has, for example, 5 to 20 carbon atoms, and the molecular weight of the dialdehydes that can be produced can be, for example, between 50 and 500 g / mol. Possible representatives of this dialdehyde group are, for example, tricyclodecane dicarbaldehyde or dicyclopentane dicarbaldehyde.

[0016] The conversion of feedstocks to products is carried out by hydroformylation of polycyclic aliphatic diolefins in the presence of synthesis gas. These dialdehydes are obtained by conversion of polycyclic aliphatic dienes, which have at least two non-aromatic rings and at least two non-adjacent double bonds. These feedstocks can have a molecular weight of, for example, 50 g / mol or more and 450 g / mol or less. The diolefins may optionally contain additional functional groups in addition to the double bonds. Possible representatives of the group of usable aliphatic polycyclic dienes are dicyclopentadiene, tricyclopentadiene, norbornadiene, etc. Mass transfer of the above polycyclic aliphatic diolefins is limited in heterogeneous reaction mixtures consisting of water and an organic phase. The homogenization in the process of the present invention makes it possible to overcome the mass transfer limitations that arise in two-phase systems.

[0017] The synthesis gas contains hydrogen and carbon monoxide, and the composition of the synthesis gas, i.e., the ratio of carbon monoxide to hydrogen, can vary. The molar ratio of hydrogen to carbon monoxide is usually between 1:10 and 10:1, with mixtures containing hydrogen and carbon monoxide in a molar ratio of 3:1 to 1:3, especially about 1:1, being particularly suitable. Per mole of diolefin, 1 to 12 moles, especially 1.2 to 10 moles, and preferably 1.5 to 8 moles of carbon monoxide and 2 to 24 moles, especially 2.4 to 20 moles, and preferably 3 to 16 moles of hydrogen can be used. It has proven useful to operate with an excess of 10 to 200 moles, especially 25 to 120 moles of carbon monoxide and 20 to 400 moles, especially 50 to 200 moles of hydrogen per mole of diolefin.

[0018] The conversion of the feedstock to aldehydes is carried out over a metal catalyst system modified with an organophosphorus ligand containing a transition metal from subgroups 8 to 10 of the Periodic Table. The catalyst used, or the catalyst system generated in the reaction solution, contains at least one transition metal from subgroups 8 to 10 of the Periodic Table of Elements, such as cobalt, rhodium, or indium. In addition to the metal, the catalyst contains at least one organophosphorus ligand containing a phosphorus atom in its coordination sphere or coordinates these in the reaction solution under reaction conditions. The organophosphorus ligand has a carbon backbone with or without additional functional groups and at least one or two covalently bonded phosphorus atoms. The catalytically active catalyst system is further formed under reaction conditions by the further access of hydrogen and carbon monoxide in the reaction vessel, whereby components of the synthesis gas form coordination complexes with the metal. However, it is also possible to first preform the catalyst and then feed it to the actual hydroformylation step. In this case, the preformation conditions generally correspond to the hydroformylation conditions.

[0019] The hydroformylation is carried out using a water-soluble triarylphosphine or water-soluble diphosphine complex catalyst, which contains a water-soluble organophosphorus compound as a ligand in its coordination sphere in the reaction solution. Examples of the water-soluble organophosphorus compound include compounds represented by the following general formula:

[0020] [ka] In the formula, Ar1, Ar2 and Ar3 represent the same or different aryl groups having 6 to 14 carbon atoms. The substituents Y1, Y2 and Y3 represent the same or different linear or branched alkyl or alkoxy residues having 1 to 4 carbon atoms, chlorine, bromine, hydroxyl, cyanide or nitro groups, and also phosphorus(III) compounds according to the formula NR 1 R 2 represents an amino group represented by the formula: 1 and R 2 may be the same or different and represent hydrogen or a linear or branched alkyl group having 1 to 4 carbon atoms. The counter cation M may represent lithium, sodium, potassium, magnesium, calcium, or barium, where m1, m2, and m3 may be the same or different and represent integers from 0 to 5, and n1, n2, and n3 may be the same or different and represent integers from 0 to 3, with at least one of the numbers n1, n2, and n3 being 1 or greater. If the solubility of the complex in water at 20°C is 100 g / L or greater, the triarylphosphine complex catalyst is a water-soluble triarylphosphine complex catalyst. Water solubility can be determined, for example, based on the OECD Guidelines for the Determination of Water Soluble ("Water Soluble" of May 27, 1995).

[0021] Water-soluble triarylphosphines of the above formula preferably include those in which Ar1, Ar2, and Ar3 are phenyl groups; and Y1, Y2, and Y3 are methyl, ethyl, methoxy, ethoxy, and / or chlorine atoms. The cationic residue M of the inorganic cation can preferably be sodium, potassium, calcium, or barium. Particularly suitable are water-soluble triarylphosphines in which Ar1, Ar2, and Ar3 are each phenyl groups; m1, m2, and m3 are 0; n1, n2, and n3 are 0 or 1; and n1 + n2 + n3 totals 1 to 3, with the sulfonate group preferably being in the meta position. The ligands can be used alone or in mixtures. Suitable examples of water-soluble triarylphosphine ligands include (sulfophenyl)diphenylphosphine, di(sulfophenyl)phenylphosphine, and tri(sulfophenylphosphine). In the prior art, (sulfophenyl)diphenylphosphine is abbreviated as TPPMS, di(sulfophenyl)phenylphosphine as TPPDS, and tri(sulfophenyl)phosphine as TPPTS.

[0022] Likewise suitable as water-soluble diphosphines are the sulfonated diphosphines of the following general formulae (III) and (IV):

[0023] [ka] In (III), n4 and n5 each independently represent 0 or 1, and the compound of formula (III) can contain up to six -SO3M groups. In (IV), n6, n7, n8 and n9 each independently represent 0 or 1, and the compound of formula (IV) contains four to eight -SO3M groups.

[0024] In formulas (III) and (IV), M represents ammonium, a monovalent metal or a polyvalent metal equivalent, particularly sodium, potassium, calcium or barium.

[0025] The catalyst metal concentration can be 20 to 1000 ppm by weight, preferably 50 to 800 ppm by weight, and particularly 100 to 600 ppm by weight, based on the total volume of the aqueous catalyst solution. While stoichiometrically configured metal-phosphorus ligand complex compounds can be used as catalysts, they are typically operated in the presence of an excess of phosphorus ligand, i.e., in the presence of a ligand that is not complexed with the metal used. Preferably, 10 to 300 moles of phosphorus in the form of a water-soluble organophosphorus ligand can be used per mole of metal. A molar ratio of metal to organophosphorus ligand ranging from 1:50 to 1:150 has been found to be particularly useful. The metal-phosphorus complex catalyst need not be homogeneous in composition and can, for example, consist of a mixture of transition metal-complex compounds differing in the type or stoichiometry of the phosphorus ligand. Similarly, the free phosphorus ligand contained in the aqueous catalyst solution can consist of a mixture of different water-soluble organophosphorus compounds.

[0026] The hydroformylation is carried out at a pressure of 0.5 MPa or more and 10 MPa or less, and at a temperature of 70°C or more and 150°C or less. The conversion according to the invention is carried out under a pressure rather low for the hydroformylation reaction and within a short process time. This can help to reduce the necessary investment in plant equipment. The selected total pressure can preferably range from 0.5 to 10 MPa, more preferably from 1 to 8 MPa, and in particular from 1.5 to 6 MPa. A temperature range of 100 to 150°C, in particular from 110 to 140°C, can be preferably maintained.

[0027] The reaction is carried out in a homogeneous liquid reaction phase, which contains at least one non-aqueous solvent, diolefins, and / or mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution. Using a selected composition consisting of the solvent, aqueous catalyst solution, polycyclic diolefins, and intermediate and final products formed therefrom during the reaction, a homogeneous liquid phase forms at the reaction site throughout the entire reaction process within a specified pressure and temperature range. This homogeneous liquid phase is used to introduce synthesis gas, which is used to further convert the unsaturated bonds to the corresponding aldehydes over the catalyst. This means that the reaction site does not have separate aqueous and organic fractions in a two-phase system where both phases form a common phase boundary. The presence of a common homogeneous phase can be thermodynamically calculated from the ratios of the amounts (an exemplary calculation result is shown in Figure 1) and can be visually confirmed during the conversion process. In addition to the above components, the homogeneous phase may also contain excess ligands and / or high molecular weight by-products.

[0028] The mass ratio of the feedstock, solvent, and aqueous catalyst solution is controlled in the solution so that a single-phase solution exists under the reaction conditions. By determining the mass ratio between the feedstock, the aqueous catalyst solution, and the solvent, a single-phase solution can be provided at the reaction site under selected temperature and pressure conditions, where the conversion of the synthesis gas according to the present invention proceeds particularly favorably. Controlling the monophasic nature here means that the mass ratio of the components is predetermined at the start of the reaction so that the solution is monophasic under the reaction conditions. Since, of course, no intermediate or final product exists at the start of the reaction, changes in the composition as the reaction progresses must be taken into account. For example, a point in a phase diagram, such as that shown in FIG. 1, can be selected that is in the single-phase region both at the start of the conversion of the feedstock and after the conversion is complete. However, it is also possible to actively control the composition during the reaction so that the reaction can proceed in the single-phase region. For example, solvent can be actively added or removed from the solution. The same can be done with the aqueous components, in which case fresh catalyst solution or only water is metered into the reaction site. The mono- or biphasic control, which is in principle possible via temperature and pressure of the plant, is less preferred.

[0029] The solvent is preferably a liquid that has at least some solubility in water. The solubility of the solvent in water may be, for example, 20 g / L or more at 20°C. The use of a solvent with this solubility ratio to water may contribute to obtaining a particularly solid single-phase region, which can reliably offset any pressure and / or temperature fluctuations that may occur. In addition, the use of such a class of solvents contributes to the fact that large changes in composition can be offset by the formation of products. Furthermore, the proportion of solvent can be kept sufficiently low, which simplifies the separation of the resulting mixture and keeps the energy costs for separation low.

[0030] In a preferred embodiment of the process, the polycyclic aliphatic diolefin can be selected from the group consisting of bicyclic or tricyclic dienes or mixtures thereof. It has been found particularly advantageous to completely convert sterically difficult cyclic diene feedstocks having internal double bonds into dialdehydes in the process according to the invention. Due to their rigid ring structure, such cyclic diene feedstocks are significantly less reactive with the catalyst complex in solution than, for example, short aliphatic chains. Due to their low solubility in the aqueous catalyst phase, these polycyclic olefinic aliphatics can only be converted very poorly in conventional process procedures in the two-phase region. While single-phase conversion in purely organic solvents is certainly possible, purification of the resulting product presents significant challenges. Furthermore, the latter conversion presents problems with catalyst recovery and its service life. For example, in purely organic solvents, unmodified (no ligand conversion) metal catalysts are also used for the diolefin conversions described herein, but they require high catalyst loadings and the catalyst is not recycled. When ligand-metal complexes are used as catalysts, desirable activities are often not achieved in the hydroformylation of polycyclic diolefins. Bicyclic or tricyclic dienes convertible according to the present invention contain two or three closed non-aromatic rings and, further, preferably have a molecular weight of at least 60 g / mol and at most 450 g / mol.

[0031] In a more preferred embodiment of the method, the polycyclic aliphatic diolefin can be selected from the group consisting of dicyclopentadiene and norbornadiene. The conversion method of the present invention can effectively convert particularly difficult-to-convert sterically and poorly water-soluble polycyclic aliphatic olefins, such as tricyclo[5.2.1.02,6]deca-3,8-diene and bicyclo[2.2.1]hepta-2,5-diene. High conversion rates can be achieved with high selectivity, and the catalyst system can also have a particularly long life.

[0032] In one preferred embodiment of the method, the temperature and pressure during the conversion can be maintained constant, and the monophasic nature of the reaction solution can be adjusted via the mass ratio of the solvent to the aqueous catalyst solution. Additionally, it has been found advantageous to essentially adjust the desired monophasic range via the mass ratio between the aqueous catalyst solution, raw materials, and solvent. In this case, a "precise" range can be obtained, thereby reliably offsetting composition changes during the course of the reaction due to the formation of intermediate and / or final products, the formation of high molecular weight by-products, and / or changes in the organophosphorus ligands. Additionally, by selecting an appropriate solvent and its amount relative to the aqueous catalyst solution, possible temperature and / or pressure fluctuations can also be offset. Through this determination, the reaction can be reliably maintained in a monophasic range overall. More preferably, this control can be determined at the start of the reaction via the selection of the amounts of solvent and aqueous catalyst solution.

[0033] In yet another preferred feature of the process, the solvent can be selected from the group consisting of linear or branched C2-C5 alcohols or a mixture of at least two alcohols from this group. It has been found that short-chain alcohols are particularly suitable for achieving particularly efficient conversions in the single-phase region. By using these solvents, even difficult-to-hydroformylate feedstocks can be converted very selectively over water-soluble catalysts within very short process times. The catalyst life can also be significantly extended by this solvent selection. These solvents exhibit a low binding affinity for the metal compared to the ligand. However, at the same time, they can act to stabilize the ligand and therefore protect it from decomposition. A further advantage is that a very robust single-phase region can be achieved using only a small proportion of solvent, which reduces the costs of workup and isolation of the desired product. The low boiling point of the selected solvent is also advantageous, allowing them to be easily separated from the reaction system.

[0034] In one preferred aspect of the process, the solvent can be isopropanol. It has been found that the use of isopropanol in the single-phase conversion of polycyclic dienes within the context of hydroformylation is particularly advantageous. By adding isopropanol, even difficult-to-hydroformylate feedstocks can be converted very selectively over a water-soluble catalyst within a very short process time. The solvent also significantly extends the catalyst's life. A further advantage is that the use of only a small proportion of isopropanol results in the formation of a very solid single-phase region, which reduces the costs of workup and separation of the desired product. Additionally, the physical differences between isopropanol and the aldehyde product allow for particularly simple and complete separation after the reaction is complete.

[0035] In one preferred embodiment of the process, the metal catalyst can be present in the reaction solution at a concentration of 0.05 molar or more and 0.75 molar or less. Single-phase conversion also allows for efficient process implementation, requiring significantly less catalyst. Using such low concentrations, highly selective conversions can be achieved within short reaction times. Without being bound by theory, this is likely also achieved by preventing or at least reducing the greater decomposition of the catalyst ligands, and therefore the catalyst system itself, through the single-phase reaction. Furthermore, by adjusting the polarity of the solution, a particularly effective inflow of synthesis gas is achieved, which may contribute to a particularly fast reaction. Without being bound by theory, a mixture of water and isopropanol may also be particularly suitable for preventing premature decomposition of the water-soluble organic ligands when the catalyst is used at very low concentrations. Preferably, the catalyst may be present in the reaction solution at a concentration of 0.1 mol / L or more and 0.65 mol / L or less, more preferably 0.2 mol / L or more and 0.55 mol / L or less.

[0036] In yet another aspect of the method, the reaction can be carried out at a pressure of 2.5 MPa or more and 7.5 MPa or less, preferably 3 MPa or more and 7 MPa or less, in particular 3.5 MPa or more and 6.5 MPa or less. Surprisingly, it has been found that for the conversion of difficult feedstocks, it is additionally particularly advantageous to carry out the reaction in a particularly low pressure range. Despite the sterically difficult feedstocks, their poor solubility, and the desired complete conversion of both double bonds, the aqueous components in the single-phase region do not appear to impede the access of the synthesis gas, so that, overall, sufficient gas introduction into the reaction solution can be ensured even at relatively low pressures.

[0037] In one preferred embodiment of the method, the weight ratio of the aqueous catalyst solution to the solvent, expressed as the weight of the catalyst solution divided by the weight of the solvent, can be 0.25 or more and 4 or less. This weight ratio has been found to be particularly reliable and advantageous for the entire single-phase reaction solution. This weight ratio can reliably compensate for inevitable fluctuations in pressure and temperature caused by the process, as well as composition changes due to product formation. Furthermore, advantageously, the amount of solvent added can be relatively small, 0.5 or more and 2 or less, but in particular 0.75 or more and 1.5 or less, based on the weight of the catalyst solution. This small amount of catalyst added can contribute to more efficient workup of the reaction solution after the reaction is completed.

[0038] In one preferred aspect of the method, the reaction can be carried out at a temperature of 120° C. or higher and 150° C. or lower. Despite the increased reactivity achieved by proceeding in the single-phase range, the temperature range described above has proven to be advantageous, particularly at a temperature of 125° C. or higher and 140° C. or lower. In this range, particularly rapid and selective conversion is obtained, while the proportion of high boilers formed remains very low. In addition, the catalyst life is significantly longer, possibly due to reduced decomposition of the organic ligands.

[0039] In yet another preferred embodiment of the method, the complex catalyst comprises a triarylphosphine ligand and a catalytic metal, wherein the molar ratio of triarylphosphine ligand to catalytic metal, expressed as moles of triarylphosphine ligand divided by moles of catalytic metal, is 3 to 15. For single-phase conversion, it has been found to be advantageous to maintain the ratio of organic ligand to catalytic metal within a narrow range, preferably 5 to 12, particularly 7 to 10. Within this ratio, conversion is highly reproducible and selective. This is likely due to the relatively low ligand concentration, which allows for higher catalyst activity. At the same time, decomposition of the organic ligand in the single-phase solution is slowed or even completely prevented. This approach may therefore contribute to more frequent and longer catalyst use.

[0040] In yet another preferred embodiment of the process, the synthesis gas can have a CO / H molar ratio, expressed as moles of CO divided by moles of H, of 0.5 or more and 2 or less. The improved inflow of synthesis gas into the homogeneous single-phase reaction solution makes it particularly advantageous to use the synthesis gas compositions described above within the scope of this conversion. Different ratios are usually used, taking into account that CO may be relatively difficult to disperse between the different phases in a two-phase process. Therefore, in addition to increasing the reaction rate, it is also possible to operate with very high resource efficiency.

[0041] In yet another embodiment of the method, the pH value of the aqueous catalyst solution can be greater than or equal to pH 4 and less than or equal to pH 10. It has been found that adjusting the pH value to the above-mentioned preferred range results in a catalyst comprising a transition metal and a water-soluble organophosphorus ligand exhibiting very high activity and selectivity for product production. This adjustment can be carried out by adding known adjusters, such as inorganic acids or bases, to the catalyst solution used. However, it is also possible and advantageous to maintain the homogeneous phase formed by the aqueous catalyst solution used within the above-mentioned pH range. Furthermore, it has been observed that the above-mentioned preferred pH adjustment results in less catalyst decomposition. In yet another preferred embodiment, the pH value can be adjusted between greater than or equal to pH 5 and less than or equal to pH 8, more preferably between greater than or equal to pH 5.5 and less than or equal to pH 7.

[0042] In one preferred embodiment of the process, the molar ratio of water to catalyst metal in the aqueous catalyst solution used, expressed as moles of water divided by moles of catalyst metal, can be greater than or equal to 5,000 and less than or equal to 60,000. This water-to-catalyst ratio has been found to be particularly advantageous, despite the fact that the accessibility of the organic feedstock to the catalyst is improved by the organic environment. This water ratio ensures complete conversion of the diene feedstock to dialdehydes and also allows the process to be designed to be single-phase. Additionally, fluctuations in reaction conditions can be reliably offset without departing from the single-phase region.

[0043] In yet another preferred feature of the process, the molar ratio of catalyst metal to polycyclic aliphatic diolefin, expressed as the molar ratio of catalyst metal to moles of diolefin, can be 0.05% or more and 0.75% or less, preferably 0.15% or more and 0.65% or less, and particularly 0.3% or more and 0.5% or less. The single-phase process allows for very efficient use of particularly low ratios of catalyst to olefin feedstock. Complete conversion to dialdehyde is achieved within a short reaction time, and catalyst life can be longer than in prior art approaches.

[0044] In one preferred embodiment of the process, at least one ligand of the water-soluble triarylphosphine complex catalyst can comprise triphenylphosphine-3,3',3"-trisulfonic acid sodium salt. The use of these triphenylphosphine ligands has proven particularly advantageous for operation in the single-phase range. In addition to the highly selective conversion to the dialdehyde, the formation of high boilers is particularly low, even over long reaction periods. This is particularly true when isopropanol is used as the solvent, in which case decomposition of the organic ligands is particularly low. [Example]

[0045] In the hydroformylation according to the present invention, dicyclopentadiene DCDP is converted to the corresponding dialdehyde in a reaction solution using an organically modified rhodium-complex catalyst according to the following reaction scheme:

[0046] [ka] As catalyst, a water-soluble complex catalyst is used, which comprises a phosphorus organic ligand of the following formula:

[0047] [ka] Isopropanol is used as the solvent to achieve a monophasic reaction system. The conversion is carried out in a stirred reactor (800 rpm) at 130 °C and a pressure of 5 MPa within a reaction time of 3 hours.

[0048] The amounts of raw materials used are as follows:

[0049] [Table 1]

[0050] An aqueous catalyst solution was prepared from rhodium and the ligand. Rh(OAc)2 was used as the rhodium source. This solution was added to the reactor together with the above amount of isopropanol. Dicyclopentadiene was metered in and the reaction was carried out for 3 hours at 5 MPa synthesis gas pressure and 130°C. After cooling and releasing the pressure in the autoclave, isopropanol was removed from the reaction mixture at 100 mbar and 40°C. The residue was then added to a phase separator, which allowed the catalyst and product phases to be separated. The product phase was examined by GC. The following composition was obtained:

[0051] [Table 2]

[0052] The above results were obtained without taking into account the proportion of solvent. The results show that nearly 100% conversion was achieved using a very low catalyst concentration of 0.45 mol % based on the diolefin. In addition, a TCD dial selectivity of about 90% was obtained. The aqueous catalyst solution used could be used in multiple tests (n>5) without loss of reactivity. This suggests that the method according to the present invention can also adequately protect the catalyst against decomposition. [Brief explanation of the drawings]

[0053] Figure 1 shows the calculated phase behavior of a three-component mixture as a function of composition at 120°C. The components include an aqueous solution of the Rh-TPPTS complex catalyst (lower left), isopropanol as the solvent (upper), and the final product TCD-dial (lower right). The shaded area contains the mass fraction of the ternary composition present in a two-phase system at this temperature. The upper unshaded triangular area represents a composition that is single-phase under the pressure and temperature conditions. Because the solubility of the olefin feedstock is not significantly different from that of the intermediate and final products, this phase diagram is representative of the entire conversion as the feedstock / product ratio varies.

[0054] Further tests were carried out using other solvents and raw materials. The test conditions for these tests were as follows:

[0055] [Table 3]

[0056] The only difference from the previously described reaction conditions was the use of n-propanol instead of isopropanol. Without optimizing the experimental conditions for the use of n-propanol, a TCD-dial product rate of 61.3% and an olefin conversion of 99.9% were obtained for the conversion of dicyclopentadiene. This indicates that this reaction can also be carried out in unbranched alcohols as solvents.

[0057] This reaction was repeated under the same process conditions as above, except that an additional 20 g of methylcyclohexane (MCH) was added as the solvent. Without optimizing the test conditions for this solvent mixture, a TCD-dial product rate of 69.15% and an olefin conversion of 99.5% were obtained, demonstrating that this reaction can also be carried out with a solvent mixture.

[0058] This reaction was repeated under the same process conditions as above. The difference from the previous reaction was that instead of dicyclopentadiene, 1-octene was used as the olefin component. Without optimizing the test conditions for the use of other olefins, a yield of 83.6% of the C9-aldehyde target component and a 98% olefin conversion were obtained. This indicates that this reaction can also be carried out using acyclic monoolefins. While this application is directed to the invention set forth in the claims, the disclosure of this application also includes: 1. A process for producing polycyclic aliphatic dialdehydes by hydroformylating polycyclic aliphatic diolefins in the presence of synthesis gas over an organophosphorus ligand-modified metal catalyst system having a transition metal of subgroups 8 to 10, wherein the hydroformylation is carried out in a homogeneous liquid reaction phase using a water-soluble diphosphine or triarylphosphine complex catalyst at a pressure of 0.5 MPa to 10 MPa and a temperature of 70°C to 150°C, wherein the homogeneous liquid phase comprises at least one non-aqueous solvent, diolefins and / or their mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution, and the mass ratio of these components in the solution is controlled so that a single-phase solution exists under the reaction conditions. 2. The method according to claim 1, wherein the polycyclic aliphatic diolefin is selected from the group consisting of bicyclic or tricyclic dienes or mixtures thereof. 3. The method according to 1. or 2., wherein the polycyclic aliphatic diolefin is selected from the group consisting of dicyclopentadiene and norbornadiene. 4. The method according to any one of 1. to 3. above, wherein the temperature and pressure are maintained constant during the conversion, and the monophasic nature of the reaction solution is adjusted via the mass ratio of the solvent to the aqueous catalyst solution. 5. The method according to any one of 1. to 4. above, wherein the solvent is selected from the group consisting of linear or branched C2 to C5 alcohols or a mixture of at least two alcohols from this group. 6. The method according to any one of 1 to 5 above, wherein the solvent is isopropanol. 7. The method according to any one of 1. to 6., wherein the metal catalyst is present in the reaction solution at a concentration of 0.05 mol or more and 0.75 mol or less. 8. The method according to any one of 1. to 7. above, wherein the reaction is carried out at a pressure of 2.5 MPa or more and 7.5 MPa or less. 9. The method according to any one of 1. to 8. above, wherein the mass ratio of the aqueous catalyst solution to the solvent, expressed as the mass of the catalyst solution divided by the mass of the solvent, is 0.25 or more and 4 or less. 10. The method according to any one of 1. to 9. above, wherein the reaction is carried out at a temperature of 120°C or higher and 150°C or lower. 11. The method according to any one of 1. to 10. above, wherein the complex catalyst comprises a triarylphosphine ligand and a catalytic metal, and wherein the molar ratio of the triarylphosphine ligand to the catalytic metal used is 8 or more and 15 or less, expressed as the number of moles of triarylphosphine ligand divided by the number of moles of catalytic metal. 12. The method according to any one of 1. to 11. above, wherein the pH value of the aqueous catalyst solution is pH 4 or more and pH 10 or less. 13. The method according to any one of 1. to 12. above, wherein the molar ratio of water in the aqueous catalyst solution used to the catalyst metal, expressed as the number of moles of water divided by the number of moles of catalyst metal, is 5,000 or more and 60,000 or less. 14. The method according to any one of 1. to 13. above, wherein the molar ratio of catalyst metal to polycyclic aliphatic diolefin, expressed as moles of catalyst metal to moles of diolefin, is 0.05% or more and 0.75% or less. 15. The method according to any one of 1. to 14., wherein at least one ligand of the water-soluble triarylphosphine complex catalyst comprises triphenylphosphine-3,3',3''-trisulfonic acid sodium salt.

Claims

1. 1. A process for producing polycyclic aliphatic dialdehydes by hydroformylating polycyclic aliphatic diolefins in the presence of synthesis gas over an organophosphorus ligand-modified metal catalyst system having a transition metal of subgroups 8 to 10, wherein the hydroformylation is carried out in a homogeneous liquid reaction phase using a water-soluble diphosphine- or triarylphosphine complex catalyst under a pressure of 0.5 MPa to 10 MPa and a temperature of 70°C to 150°C, wherein the homogeneous liquid phase comprises at least one non-aqueous solvent, diolefins and / or their mono- and / or dialdehydes as reaction products, and an aqueous catalyst solution, the mass ratio of these components in the solution being controlled so that a single-phase solution exists under the reaction conditions, and the mass ratio of the aqueous catalyst solution to the solvent, expressed as the mass of the catalyst solution divided by the mass of the solvent, is 0.25 to 4.

2. 10. The process of claim 1, wherein the polycyclic aliphatic diolefin is selected from the group consisting of bicyclic or tricyclic dienes or mixtures thereof.

3. 3. The process of claim 1 or 2, wherein the polycyclic aliphatic diolefin is selected from the group consisting of dicyclopentadiene or norbornadiene.

4. 4. The process according to claim 1, wherein the temperature and pressure are kept constant during the conversion and the monophasic nature of the reaction solution is adjusted via the mass ratio of the solvent to the aqueous catalyst solution.

5. 5. The method according to claim 1, wherein the solvent is selected from the group consisting of linear or branched C2-C5 alcohols or a mixture of at least two alcohols from this group.

6. The method according to any one of claims 1 to 5, wherein the solvent is isopropanol.

7. 7. The method of claim 1, wherein the metal catalyst is present in the reaction solution at a concentration of at least 0.05 molar and at most 0.75 molar.

8. The method according to any one of claims 1 to 7, wherein the reaction is carried out at a pressure of 2.5 MPa or more and 7.5 MPa or less.

9. The method according to any one of claims 1 to 8, wherein the reaction is carried out at a temperature of 120°C or higher and 150°C or lower.

10. 10. The method of any one of claims 1 to 9, wherein the complex catalyst comprises a triarylphosphine ligand and a catalytic metal, wherein the molar ratio of triarylphosphine ligand used to catalytic metal is 8 or more and 15 or less, expressed as moles of triarylphosphine ligand divided by moles of catalytic metal.

11. The method according to any one of claims 1 to 10, wherein the pH value of the aqueous catalyst solution is greater than or equal to pH 4 and less than or equal to pH 10.

12. 12. The process according to claim 1, wherein the molar ratio of water in the aqueous catalytic solution used to catalytic metal, expressed as moles of water divided by moles of catalytic metal, is greater than or equal to 5,000 and less than or equal to 60,000.

13. 13. The process of any one of claims 1 to 12, wherein the molar ratio of catalyst metal to polycyclic aliphatic diolefin, expressed as moles of catalyst metal to moles of diolefin, is 0.05% or more and 0.75% or less.

14. The method of any one of claims 1 to 13, wherein at least one ligand of the water-soluble triarylphosphine complex catalyst comprises triphenylphosphine-3,3',3''-trisulfonic acid sodium salt.

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