DE10108475A1 - Process for the preparation of aldehydes - Google Patents

Abstract

The invention relates to a two-step hydro formylation method, wherein the first step is carried out in a homogenous manner using a dissolved rhodium complex catalystors and the waste gas is introduced to a second hydro formylation step, wherein the olefinically unsaturated compounds contained in the waste gas are hydro formulated in a homogenous reaction system in the presence of xanthene skeleton based diphosphines.

Description

The invention relates to an improved process for hydroformylation olefi nically unsaturated compounds in using the with the exhaust unreacted olefins escaping from the hydroformylation zone.

It is known that compounds which contain olefinic double bonds with carbon monoxide and hydrogen to form aldehydes (Oxosyn thesis). The process is not based on the use of olefinic hydrocarbons limited, but also extends to raw materials other than that Double bond still have functional groups, mainly those that remain unchanged under the reaction conditions.

Classic oxosynthesis works with cobalt as a catalyst. Its effect Samkeit is based on the formation of cobalt carbonyl compounds under the Exposure to hydrogen and carbon monoxide at pressures above 20 MPa and temperatures of about 120 ° C and more on metallic cobalt or cobalt compounds.

In the course of the further development of oxo synthesis, cobalt became increasingly replaced by rhodium as catalyst metal. Rhodium is used as a complex ver bond used, which in addition to carbon monoxide, preferably phosphines  Contains ligands. Rhodium as a metal allows it to close at low pressures work, moreover, higher yields are achieved and preferred formed more valuable unbranched products for further processing, if one assumes straight-chain terminal olefins.

Such a process is known from US-A-3,527,809 under the designation Never derdruck rhodium process known. An improvement on this process discloses US-A-4,148,830. According to this procedure, the Kataly catalyst life and the yield of linear aldehydes are increased, if one before as a solvent for the catalyst and in excess Phosphine is the high-boiling condensation products of the structures ten aldehydes used. The removal of insoluble Rhodi avoid reconnections and the dissolved catalyst can be used in many Reuse catalytic cycles without a decrease in activity vity observed. The method known from US-A-4,148,830 is also known as "Hydroformylation process with liquid recycle" referred to.

For reasons of process economy, especially around large reactors or To avoid long reaction times, one does not lead the implementation to complete consumption of the olefinically unsaturated compounds, but is often satisfied with the conversion of only 60 to 95% of the off gear to the desired end connection. In the exhaust gas that the Hydro formylation zone leaves, are therefore next to excess Koh lenmonoxide and hydrogen unreacted olefin feed, which has been converted into valuable materials according to differently designed processes can be delt.

The implementation contained in the exhaust gas of a first hydroformylation zone NEN olefinically unsaturated compounds in a downstream second Hydroformylation zone is known from EP-A1-0 188 246. In the first Stage is recycling liquid or gas olefin, carbon mon oxide and hydrogen in the presence of a soluble rhodium-phosphorus complex catalyst,  free phosphorus ligand and higher boiling aldehyde Condensation by-products implemented. The exhaust gas, it contains olefin, optionally aldehyde, also hydrogen, carbon monoxide and alkane-Ne benproduct, is a decoupled, d. H. be separate from the first stage driven secondary rhodium-catalyzed hydroformylation process fed in, with the recirculation of liquid or gas, the exhaust gas together with added carbon monoxide and hydrogen for reaction brought. The known method also allows the implementation of Olefins, which are a mixture of terminal and internal olefinic compounds conditions are available, such as. B. a mixture of isomeric butenes. In the first The reaction stage is predominantly the terminal one and in the second Reaction stage the internal olefins contained in the exhaust gas for reaction brought.

Such a process variant is particularly important, in which the second reaction stage carried out under such reaction conditions is, among which the internal olefins with high selectivity in the ge Radkettigen aldehydes are transferred. The transfer from inside EP-B1-0 213 639 describes olefins in the straight-chain aldehydes with high selectivity known in which special diphosphites are used as ligands.

However, the widespread use of diphosphite ligands is reflected in their im Lower stability and higher compared to conventional phosphine ligands Here sensitivity to hydrolysis towards traces of water and acid limits and that during the continuously operated hydroformyly The process formed phosphonous acids affect the catalytic converter gate life and have to be removed from the process, z. B. by treating the catalyst-containing solution with an alkali ion exchangers before their return to the hydroformylation process.  

The methods known from the prior art allow a high one Implementation of the olefinically unsaturated compounds used to. Aldehydes. However, since the straight-chain unbranched aldehydes in general my preferred, there is a need for a method for hydro formylation of olefinically unsaturated compounds with high conversion and at the same time high selectivity to the straight-chain unbranched aldehydes the. The known diphosphite ligands make hydroformyly possible tion of internal olefins to straight-chain aldehydes with high Se selectivity, but diphosphite ligands tend to be prone to their known hydrolysis Sensitivity to the formation of phosphonous acids, which are harmful can affect the rhodium complex catalyst and thus to a shortening increase the catalyst life.

It was therefore the task to develop a process that it under economically acceptable conditions allowed, olefinic, in the exhaust gas Compounds containing hydroformylation reaction, with high selectivity to implement the straight chain carbonyl compounds, which is ready processes to be delivered show an advantageously long catalyst life should.

The invention therefore consists in a process for the hydroformylation of olefinically unsaturated compounds, the reaction in a first stage of reaction in a homogeneous reaction system using organic phosphorus (III) compounds in complex bonds containing rhodium compounds as catalysts at pressures of 0.2 up to 20.0 MPa and exhaust gas is bidded. It is characterized in that the exhaust gas is fed to the first reaction stage of a second reaction stage in which amounts of the olefinically unsaturated compounds present in the exhaust gas in a homogeneous reaction system in the presence of complex compounds of rhodium and diphosphines of the general formula (I)

in which R ¹ and R ^{2 are} each the same or different (C ₁ -C ₁₈ ) alkyl radicals, (C ₆ -C ₁₄ ) aryl radicals, (C ₇ -C ₂₄ ) aralkyl radicals or (C ₇ -C ₂₄ ) -alkylaryl radicals, R ^{3 represents} hydrogen or a radical -CHR ^a R ^b , in which R ^a and R ^{b are} each the same or different hydrogen, (C ₁ -C ₁₈ ) -alkyl-, (C ₁ -C ₈ ) alkoxy residues, unsubstituted or substituted with (C ₁ -C ₁₀ ) alkyl and / or (C ₁ -C ₁₀ ) alkoxy residues (C ₆ -C ₁₄ ) aryl residues or Are (C ₇ -C ₂₄ ) aralkyl residues, and R ^{4 are} (C ₁ -C ₁₀ ) alkyl residues, (C ₆ -C ₁₄ ) aryl residues, (C ₇ -C ₂₄ ) aralkyl residues Residues or (C ₇ -C ₂₄ ) - represent alkylaryl residues, who are implemented at pressures of 0.2 to 20 MPa.

These diphosphines are derived from the xanthene structure as a base and attached oxaphosphine rings. The diphosphines of the general Formula I and its manufacturing process is the subject of the same day Patent application filed to the hereby expressly referenced men will ("incorporated by reference").

Among the diphosphines of the general formula I, those diphosphines are particularly suitable in which R ¹ and R ^{2 are} each the same or different (C ₁ -C ₁₂ ) alkyl radicals, (C ₆ -C ₁₀ ) aryl radicals, (C Are ₇ -C ₁₀ ) aralkyl radicals or (C ₇ - C ₁₀ ) alkylaryl radicals,
R ^{3 represents} hydrogen or a radical -CHR ^a R ^b , in which R ^a and R ^{b are} each the same or different hydrogen, (C ₁ -C ₁₂ ) alkyl, (C ₁ -C ₄ ) alkoxy radicals, unsubstituted or with (C ₁ -C ₈ ) alkyl and / or (C ₁ -C ₄ ) alkoxy radicals substituted (C ₆ -C ₁₀ ) aryl radicals or (C ₇ -C ₁₀ ) aralkyl radicals Are residues, and R ^{4 is} (C ₁ -C ₈ ) alkyl residues, (C ₆ -C ₁₀ ) aryl residues, (C ₇ -C ₁₀ ) aralkyl residues or (C ₇ -C ₁₀ ) - Represent alkylaryl radicals.

The aryl radical is preferably in each case the phenyl or the naphthyl radical, the benzyl radical is preferably used as the aralkyl radical.

For example, R ¹ and R ^{2 are} identical or different and are methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tertiary butyl, n-pentyl, i-pentyl, n-he xyl, i-hexyl, n-heptyl, i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl, tolyl or benzyl.

R ³ stands for example for methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, n-pentyl, i-pentyl, 3,3-dimethylbutyl, n-hexyl, i-hexyl, n-heptyl, i -Heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl, tolyl or benzyl.

R ⁴ stands for example for methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tertiary butyl, n-pentyl, i-pentyl, 3,3-dimethylbutyl, n-hexyl, i-hexyl, n- Heptyl, i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl, tolyl or benzyl.

The new process ensures that most of the exhaust gas in the first stage unreacted olefinic compounds to straight-chain Aldehydes is hydroformylated.

The starting material for the overall process is not only olefinically un saturated compounds with terminal double bonds limited. The process according to the invention is also sol for hydroformylation Suitable starting olefins in which the terminal and internal  Double bond is present in a molecule or as a mixture of olefins are available in technology with terminal and internal double bonds. Such a mixture is, for example, a mixture of isomeric butenes.

In particular, the new process succeeds in containing the exhaust gas olefinically unsaturated compounds with internal double bonds, which only react to a minor extent in the first stage, to linear ones Implement aldehydes. In this way, based on the Ge velvet process, in addition to excellent sales of the olefinically unsaturated Compounds to the carbonyl compounds also have high selectivities achieve the desired straight-chain carbonyl compounds.

The high efficiency of the process according to the invention was not to be expected see. Firstly, it should be noted that the olefinically unsaturated verb doses in the exhaust gas are present in considerable dilution and their contents can be between 20 and 65% by weight, depending on the olefin used NEN. Despite the low initial concentration of olefinically unsaturated Compounds can be the second stage of hydroformylation with a high Sales are driven.

Surprisingly, those in the second hydroformylation prove stage diphosphine ligands used according to the invention of the general Formula (I) as very stable. Therefore, it is possible to process the whole process over many Catalytic cycles without a decrease in activity and selectivity. A frequently carried out and expensive catalyst workup therefore only a few catalytic cycles are omitted.

The first reaction stage of the new process is carried out in a homogeneous one reaction system. The term homogeneous reaction system is used for one consisting essentially of solvent, catalyst, olefinically unsaturated compound and reaction product composed homogeneous Lö solution. The higher-boiling solvents have proven to be particularly effective  Condensation compounds of the aldehydes to be produced, in particular the trimers of the aldehydes to be produced, which proved to be a minor products in the hydroformylation, as well as their mixtures with the to produce aldehydes, so that no further solvent addition is absolutely necessary. In some cases, however, there may be a solution additional funds prove to be appropriate. Organic solvents Compounds used in which the starting material, reaction product and Catalyst system are soluble. Examples of such compounds are aro Matic hydrocarbons such as benzene and toluene or the isomeric Xy lole and mesitylene. Other common solvents are paraffin oil, Cyclohexane, n-hexane, n-heptane or n-octane, ethers, such as tetrahydrofuran, Ketones or Texanol® from Eastman. The proportion of the solvent in the Reaction medium can be varied over a wide range and be usually carries between 20 and 90% by weight, preferably 50 to 80% by weight, based on the reaction mixture.

Rhodium complex compounds are used as catalysts, the contain organic phosphorus (III) compounds as ligands. such Complex compounds and their preparation are known (e.g. from US Pat. No. 3,527,809, US-A-4 148 830, US-A-4 247 486, US-A-4 283 562). You can as uniform complex compounds or as a mixture of different ones Complex compounds are used. The rhodium concentration in the Reaction medium ranges from about 1 to about 1000 ppm by weight and is preferably 10 to 700 ppm by weight. Inbeson rhodium is used in concentrations of 25 to 500 ppm by weight, each based on the homogeneous reaction mixture. As a catalyst can the stoichiometrically composed rhodium complex compound Find application. However, it has proven to be useful Hydroformylation in the presence of a rhodium- Phosphorus complex and free, i.e. H. excess phosphorli ganden perform that with rhodium no more complex connection received. The free phosphorus ligand can be the same as in the rhodium  Complex compound, but it can also be different from this ligan which are used. The free ligand can be a unitary compound be or from a mixture of different organophosphorus compounds consist. Examples of rhodium-phosphorus complex compounds that as Catalysts can be used are described in US-A-3,527,809 ben. Among the preferred ligands in the rhodium complex catalysts count z. B. triarylphosphines such as triphenylphosphine, trialkylphosphines such Tri (n-octyl) phosphine, trilaurylphosphine, tri (cyclohexyl) phosphine, alkylphenyl phosphines, cycloalkylphenylphosphines and organic diphosphites. Because of Triphenylphosphine is particularly popular for its easy accessibility looking.

The molar amount is usually in the homogeneous reaction mixture Ratio of rhodium to phosphorus 1: 1 to 1: 1000, however, the molar proportion of phosphorus in the form of organic phosphorus compounds also be higher. Rhodium and organically bound are preferably used NEN phosphor in a molar ratio of 1: 3 to 1: 500. At the An The use of triarylphosphines have in particular rhodium to Phos Phor molar ratios of 1:50 to 1: 300 have proven successful. Become trialkylphos phine used as ligand, the molar ratio of rhodium to Phosphorus preferably 1: 3 to 1: 100.

The conditions under which the implementation in the first reaction stage expires, can vary within wide limits and the individual Conditions to be adjusted. You hang u. a. from the feed, from selected catalyst system and the desired degree of implementation from. The hydroformylation of the starting materials is usually carried out Temperatures from 50 to 160 ° C. Temperatures are preferred from 60 to 150 ° C and in particular from 75 to 140 ° C. The total pressure extends over a range of 0.2 to 20.0 MPa, preferably 1 to 12 MPa and especially 1 to 7 MPa. The molar ratio of water Substance to carbon monoxide usually ranges between 1:10 and 10: 1,  Mixtures containing hydrogen and carbon monoxide in a molar ratio of 3: 1 up to 1: 3, in particular about 1: 1, are particularly suitable.

The catalyst is usually formed from the components rhodium or rhodium compound, organic phosphorus compound and synthesis gas under the conditions of the hydroformylation reaction in the reaction mixture mixed. However, it is also possible to preform the catalyst first and then feed it to the actual hydroformylation stage. The conditions of preforming generally correspond to Hydroformylation.

The reaction conditions in the first stage can be selected that targeted the olefinically unsaturated compounds with terminal Double bonds are reacted. Conveniently who which the reaction conditions set so that the reaction with possible selectivity to the straight-chain aldehydes. That too Selectivities to achieve straight-chain aldehydes are described in particularly from the phosphorus-containing ligand used influenced. Even if in individual cases in the first stage also on one more or less large partial turnover is worked on, you can in the first Step depending on the phosphine ligand used an aldehyde obtained mixture with a fairly high proportion of branched aldehydes. If you want to target an aldehyde mixture with a high content of straight chain aldehydes are such known phosphite ligands, for example to choose triaryl phosphites, which is known to prefer provide linear aldehydes.

If a mixture of olefins with end and internal double bond, e.g. B. selects a mixture of isomeric butenes one expediently those reaction conditions under which the Olefins with a terminal double bond are preferably implemented. The  unreacted olefins, mostly those with an internal double bond dung, are therefore enriched in the exhaust gas of the first reaction stage.

The reaction product of the first reaction stage is from the catalyst separated, for example distilled off. The one after separation of the aldehyde remaining residue containing the catalyst, if necessary after adding fresh catalyst and removing part of the process the reaction formed aldehyde condensation products in the reaction zone.

The exhaust gas (exhaust gas stream) escaping from the first reaction stage sets composed of the exhaust gas that is taken directly from the reactor is (reactor exhaust gas) to an enrichment of inert in the, in the circuit to avoid guided gas mixture and the gaseous proportions that the separation of catalyst and crude reaction product, e.g. B. at De Stillation of the aldehyde from the reaction product. (Product gas). The exhaust gas stream essentially consists of unreacted olefinic Compound, carbon monoxide, carbon dioxide, hydrogen and the hydrie products of the olefin. If olefinically unsaturated compounds are used with terminal double bonds as the starting olefin for the overall pro eats, the exhaust gas stream only contains residual amounts of olefinically un saturated compound, depending on whether a partial turnover or a almost complete sales in the first stage is aimed for. Contains that Starting material for the inventive process olefins with inside constant double bonds, they are only in the first stage to a lesser extent and these are therefore in the exhaust gas flow gereichert.

The exhaust gas stream is generally without further intermediate treatment, especially without cleaning, but if necessary after adding Hydrogen alone or in a mixture with carbon monoxide as feed abandoned a second hydroformylation stage. In separate cases  However, it may prove useful to have the exhaust gas flow before Use in the second hydroformylation stage to clean it.

The second hydroformylation stage is decoupled, i. H. independent of first hydroformylation stage with one of the first hydroformyly tion stage operated different catalyst. Implementation of the Exhaust gas flow amounts of olefinically unsaturated compounds also takes place in a homogeneous manner, as in the first reaction stage Reaction system with carbon monoxide and hydrogen. As a solvent such solvents are used, which are also in the first Re action level.

Rhodium complex compounds are used as catalysts, the contain diphosphines of the general formula (I) as ligands.

Among the diphosphines of the general formula I are especially those Diphosphines are suitable as ligands, on the one hand in the reaction mixture are readily soluble so that it can be used in many catalyzes under process conditions There is no precipitation of the diphosphine itself during the cycles. On the other hand, the diphosphines and the Rho derived from them dium complex compounds under the hydroformylation conditions have a high long-term stability and thus a homogeneous reaction ensure leadership over many catalytic cycles. A reference to one high long-term stability is the constant homogeneity of the organic Catalyst solution over many catalytic cycles, since the Rho dium-containing complex compounds and the ligands in general in have only a low solubility in the organic solvent and fail.

The following diphosphines are particularly suitable: 2,7-bis (3,3-dimethylbu tyl) -9,9-dimethyl-4,5-bis (2,7-dimethyl-10-phenoxaphosphino) xanthene (II), 2,7,9-trimethyl-9-n-nonyl-4,5-bis xanthene (2,7-dimethyl-10-phenoxaphosphino)  (III), 2,7-di-n-decyl-9,9-dimethyl-4,5-bis (2,7-dimethyl-10- phenoxaphosphino) xanthene (IV), 2,7-di-nhexyl-9,9-dimethyl-4,5-bis (2,7-di methyl-10-phenoxaphosphino) xanthene (V), 2,7- (3,3-dimethylbutyl) -9,9-dime thyl-4,5-bis [2,7-di (3,3-dimethylbutyl) -10-phenoxaphosphino] xanthene (VI), 2,7- Dimethyl-9,9-dimethyl-4,5-bis [2,7-di (3,3-dimethylbutyl) -10-phenoxaphos phino] xanthene (VII).  

The sufficient solubility of the diphosphines is of particular importance of the general formula I in the reaction mixture, which is so high that it under process conditions even over many catalytic cycles Precipitation of the ligand is coming.

The solubility of the individual ligands does not follow any easily understandable laws. Surprisingly, it was found that the radicals R ³ on the two aromatic carbon rings of the xanthene skeleton in the general formula I can have a particularly strong influence on the solubility, while the introduction of the substituents R ⁴ on the phenoxa phosphine radical alone takes only one shows very little influence on the solubility.

The increase in carbon atoms is not a criterion on which the soluble behavior can be read. Also solubility of the xanthene scaffold without phenoxaphosphine substituents not on that Solubility behavior of the ligand with phenoxaphosphine substituents conclude.

The solubility behavior of the diphosphines of the general formula I and the diphosphines which are particularly suitable for the process according to the invention (II) to (VII) will be filed in the same day as the patent application acts, to which express reference is hereby made ("incorporated by reference ").

It has surprisingly been found that when using the Diphosphines of the general formula I and especially the diphosphines of the formula II to VII for the continuous reaction in the Hydroformylation sufficient concentration of diphosphine in the reactor solution can be set. In particular, the diphosphines II, IV, V and VI have excellent solubility in the reaction mixture.  

Those obtained from rhodium and diphosphines of the general formula I. Complex compounds can be used as uniform complex compounds or can be used as a mixture of different complex compounds. The Rhodium concentration ranges from 1 to 1000 ppm by weight and is preferably 50 to 500 ppm by weight. In particular rhodium is used in concentrations of 100 to 300 ppm by weight, in each case based on the homogeneous reaction mixture. The phosphorus (III) con concentration in the form of the diphosphines can be up to due to their solubility a value of 4 mol P (III) per kilogram of homogeneous reaction solution be put. The phosphorus (III) content usually moves in the Re action mixture between 10 to 400 mmol P (III), preferably 10-100 mmol P (III) and in particular 10-50 mmol P (III) per kilogram of reaction gene mixed.

As in the first reaction stage, the catalyst can be stoichiometric Compound rhodium complex compound find application. It has However, the hydroformylation in the presence has proven to be expedient a catalyst system made of rhodium-diphosphine complex compounds and free diphosphine, i.e. H. to carry out excess diphosphine which no more complex compound is formed with rhodium. The free diphosphine can be the same as in the rhodium complex compound, it can but also diphosphines other than this used as ligands become. The free ligand can be a unitary compound or from consist of a mixture of different diphosphines. Preferably ver 1 to 20 mol of phosphorus is used per mol of rhodium in the form of the diphos phine, but the molar proportion of phosphorus can also be higher. on due to the good solubility of the diphosphines used according to the invention can also be a higher molar ratio of up to 80 mol phosphorus per mol Adjust rhodium. However, it is advisable to work with smaller ones Molar ratios of up to 20 mol phosphorus per mol rhodium.  

When using

the molar ratio of rhodium to phosphorus was 1:15 proven.

The reaction pressure in the second stage of the overall process lies in the loading ranges from 0.2 to 20.0 MPa. It has proven particularly useful to use pressures between 1 and 12 MPa and in particular between 1 and 5 MPa. The Composition of the synthesis gas for the second hydroformylation level can vary over a wide range. Generally the molar is Ratio between carbon monoxide and hydrogen between 1:10 and 10: 1. Mixtures containing carbon monoxide and hydrogen in a molar ratio nis of 1: 2 and 2: 1 are particularly suitable. In particular it has proved to be expedient, synthesis gas with a light hydrogen Use excess.

The reaction temperatures in the second stage of the new process towards 50 to 160 ° C. Temperatures from 60 to 150 ° C and especially 75 to 140 ° C are preferred.

Rhodium is used either as a metal or as a compound. In metallic form, it is used either as finely divided particles or in a thin layer on a support, such as activated carbon, calcium carbonate, aluminum silicate, or alumina. Suitable rhodium compounds are salts of aliphatic mono- and polycarboxylic acids, such as rhodium 2-ethyl hexanoate, rhodium acetate, rhodium oxalate, rhodium propionate or rhodium ummalonate. Furthermore, rhodium salts of inorganic hydrogen and oxygen acids, such as rhodium nitrate or rhodium sulfate, the various rhodium oxides or rhodium carbonyl compounds such as Rh ₃ (CO) ₁₂ or Rh ₆ (CO) ₁₆ or complex compounds of rhodium, e.g. B. Cyclopentadienylrhodiumverbindungen or rhodium acetylacetonate, are used. Rhodium halogen compounds are less suitable because of their corrosive behavior of the halide ions.

Rhodium oxide and in particular rhodium acetate and Rho are preferred dium-2-ethylhexanoate. Rhodium metal and the catalyst production for Rhodium compounds suitable for the second reaction stage can be also used for the catalyst preparation in the first reaction stage the.

The catalyst is usually formed from the components rhodium or rhodium compound, the diphosphine or the diphosphines of all base formula I and synthesis gas under the conditions of Hydrofor mylation reaction in the reaction mixture. But it is also possible to use the Ka to preform the Talysator and then the actual one Hydroformylation stage. The conditions of preforming generally correspond to the hydroformylation conditions.

According to a tried and tested embodiment, the raw aldehyde he leads Most reaction stage in a stripping column in countercurrent to fresh Synthesis gas. Here, heat is transferred from the aldehyde to the synthesis gas wear and the olefinic compound dissolved in the aldehyde from the Rohpro ducted and again together with the heated synthesis gas forwarded to the reaction.  

The implementation can be carried out batchwise or continuously leads. The reaction product of the second reaction stage is from Distilled off catalyst. It can be combined with the product of the first stage and further processed, e.g. B. distilled. After the Al dehyds remaining, the catalyst containing distillation residue second stage is, if necessary after adding fresh catalyst and Ent part of the aldehyde condensate formed in the course of the reaction tion products, returned to the second hydroformylation stage.

The implementation of the olefinically unsaturated Ver contained in the exhaust gas stream bonds in the second reaction stage in the presence of the invention rhodium-diphosphine complex compounds, gives the desired linear aldehydes with excellent selectivity. Furthermore, it stands out Kata used according to the invention in the second hydroformylation stage analyzer system due to a long catalyst life.

The second stage is generally run up to a partial turnover ensure a high selectivity to the straight-chain aldehydes and for excessive damage to the catalyst and excess Li to avoid.

In terms of the overall process, it is possible according to the new process Lich, olefinically unsaturated compounds with high sales with out selectivity into linear aldehydes.

By choosing the reaction conditions in the first and second stages, the sales and selectivity z. B. by the choice of organic Controlling phosphine or phosphite ligands in the first stage opens that new methods the possibility of the proportions of n and iso compounds in the Reaction product on the overall process the respective requirements adapt. According to a further embodiment of the invention  The ratio of n- and iso-compound in the overall process can can also be influenced by the addition of olefin to the exhaust gas mixture, which is fed to the second hydroformylation stage.

The inventive method can be applied to olefinically unsaturated compounds of any structure. Accordingly, suitable starting materials are both olefins with an internal and also a terminal double bond and straight-chain and branched olefins. In addition, the olefins can also contain functional groups, in particular those which are not changed in the course of the reaction. Also polyolefinically unsaturated compounds are suitable as feedstocks, such as. B. 1,3-butadiene or 1,3 pentadiene. Mixtures of olefinically unsaturated compounds with terminal and internal double bonds are also suitable. In particular, the mixture of butene-1 and butene-2 available in the art, also referred to as raffinate II, a butene-1-depleted raffinate II, which is also referred to as raffinate III, or an octene-2 and / or octene-3 containing C ₈ -olefin mixture, can be used as starting compound in the process according to the invention. The process according to the invention is particularly suitable for the hydroformylation of olefinically unsaturated hydrocarbons having 4 to 12 carbon atoms. Suitable olefinically unsaturated compounds are, for example, butene-2, mixtures containing butene-2 and butene-1, octene-3, undecene-3, hexene-2, heptene-3, dimeric butenes, trimer propylene, technically available olefin mixtures such as Dimersol® or Octol®.

The aldehyde mixtures obtained from the first and second reaction stages Sche are separated and combined, cleaned if necessary, and on processed. Depending on the subsequent processes, it is too possible to mix the crude aldehyde directly, d. H. without additional cleaning step to implement further.  

Another embodiment of the present invention relates to a method for the production of carboxylic acids, alcohols or amines from olefinically un saturated compounds, the olefinically unsaturated compounds hydroformylated by the process according to the invention and thus obtained NEN aldehydes oxidized to carboxylic acids in a manner known per se, to Al alcohols are reduced or reductively aminated to amines.

The oxidation of the olefinically unsaturated compounds according to the invention aldehydes obtained can in a conventional manner, for example wise by the oxidation of the aldehydes with atmospheric oxygen or oxygen according to the procedures such. B. in Ullmann's Encyclopedia of Industrial Che mistry, 5th edition, Vol. A5, p. 239, VCH publishing company, Weinheim, 1986 are shown.

The catalytic hydrogenation of the process according to the invention Aldehydes obtained from olefinically unsaturated compounds to give alcohol len can be done in a manner known per se, for example according to the method von Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Vol. A1, p. 279, VCH publishing company, Weinheim, 1985 or G. H. Ludwig, hydrocarbon Processing, March 1993, p. 67.

The reductive amination of the aldehydes obtained from olefinically unsaturated compounds by the process according to the invention can be carried out in a manner known per se, for example according to 1985 from Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, vol. A2, 51, VCH Verlagsgesellschaft, Weinheim become. Both ammonia, primary C ₁ -C ₂₀ amines or secondary C ₂ -C ₂₀ amines can be used as starting compounds for the production of amines.

The new process is particularly suitable for the hydroformylation of mixtures containing butene-1 and butene-2, which are necessarily obtained in considerable quantities as refinery by-products in the production of automotive fuels and in the production of ethylene by thermal cracking of higher hydrocarbons. They are obtained from the C ₄ crack cuts of the pyrolysis product by extracting the butadiene with a selective solvent and then separating off the isobutene, preferably by converting it to methyl tert-butyl ether. The pyrolysis product freed from butadiene is referred to as raffinate I. If isobutene is also removed, this is referred to as raffinate II. Instead of extracting the butadiene, it can also be partially hydrogenated to butenes in the C ₄ crack cut. After the isobutene has been separated off, a butene-1 / butene-2 mixture is obtained, which can be converted into n-valeraldehyde with high selectivity by the new process. The first homogeneous hydroformylation stage is operated under conditions in which the butene-1 contained in the butene mixture is converted as far as possible to give n-valeraldehyde while the i-valeraldehyde formation is largely avoided. Depending on the reaction parameters chosen, the butene-1 conversion can be up to 95%, the valeraldehyde obtained after the first stage containing 90% and more n-valeraldehyde, while the rest is i-valeraldehyde. In the first stage, unreacted olefin, which mainly consists of butene-2 and which is often also referred to as raffinate III, is reacted according to the new process in the second stage in a homogeneous reaction. Depending on the reaction conditions, the olefin conversions are up to 90%, the resulting aldehyde mixture containing up to 90% by weight of n-valeraldehyde. In general, only a partial conversion of olefin is aimed for in the second stage in order to avoid excessive thermal stress on the reaction mixture and to suppress an increased formation of i-valeraldehyde. Seen over the entire process, the butene conversion is up to 95% with selectivities to n-valeraldehyde of up to 90%.

A further embodiment of the process according to the invention consists in the production of C ₁₀ carboxylic acids and C ₁₀ alcohols from a mixture containing butene-1 and butene-2, which is converted to C ₅ -aldehydes by the process according to the invention.

The combined C ₅ -aldehyde mixture of the first and second hydroformylation stages is first aldolized in a conventional manner in the presence of basic catalysts. Pretreatment of the aldehydes, e.g. B. a special cleaning is not required. As catalysts, alkali metal carbonates or alkali metal hydroxides, in particular compounds of sodium or potassium and amines, preferably tertiary amines, such as triethylamine, tri-n-propylamine, tri-n-butylamine, are used. One works at temperatures from 60 to 160 ° C, in particular 80 to 130 ° C and at normal pressure or at up to about 1 MPa increased pressure. The reaction time is a few minutes to several hours and depends in particular on the catalyst type and reaction temperature. Due to its higher reaction rate, aldolized primarily n-valeraldehyde with itself or with isomeric valeraldehydes to decenals, but condensation of 2-methyl butanal or isoveraldehyde with one another completely disappears into the background.

The aldehyde mixture obtained by condensation can, depending on the choice of Hydrogenation conditions either partially to the decanal or completely to the Decyl alcohol can be reduced. The partial hydrogenation to the decanal and the subsequent oxidation with air or atmospheric oxygen to the decan carboxylic acid takes place in a known manner, for example analogously to that from Ullmanns Ency Klopedia of technical chemistry, 4th edition 1975, Volume 9, p. 144 known Process for the preparation of 2-ethylhexanoic acid. The preserved decan car bonic acid has a high content of 2-propylheptanoic acid th.

For complete hydrogen deposition on the decenal to decyl alcohol ar is processed in a manner known per se with conventional hydrogenation catalyst ren, such as B. with catalysts based on nickel, chromium or copper. Usually  the hydrogenation temperature is between 100 and 180 ° C and Pressure between 1 and 10 MPa. That after cleaning by distillation Decyl alcohol mixture is suitable due to its high content of 2-Pro pylheptanol excellent as an alcohol component in phthalic esters, which as Find plasticizers. Plasticizer based on the after Draw obtained decyl alcohol mixture according to the method of the invention is characterized by excellent cold properties.

The production of phthalic acid is, for example, from Ullmann, Encyclopä die der Technische Chemie, 1979, Vol. 18, page 536 ff. expedient Phtalic anhydride is added with the decyl alcohol mixture in a molver Ratio 1: 2 in one stage. The reaction rate can be determined by Ka talysators and / or increased by increasing the reaction temperature the. In order to shift the equilibrium towards the formation of esters it is necessary to remove the water formed from the reaction mixture NEN.

The invention is explained in more detail in the examples below, however not limited to the described embodiments.

example 1 1st stage

Hydroformylation of raffinate II with a composition of 8.8 vol. % Butanes, 66.2% by volume of 1-butene and 22.2% by volume of cis and trans 2-butenes with a homogeneous rhodium / TPP catalyst solution

A 1 l stainless steel autoclave equipped with a stirrer was fed 130 g / h of raffinate II of the above-mentioned composition and 110 Nl / h of CO / H ₂ mixture consisting of equal parts by volume so that 10 Nl / h of exhaust gas could be removed from the reactor [Nl / h means 1 liter of exhaust gas in the normal state (20 ° C and 1 at) per hour]. At the same time, 165 g of TPP were dissolved in 830 g of a mixture of n-valeraldehyde and 2-propylheptenal (weight ratio 2: 1) and passed in circles through the reactor. 134 ml of rhodium 2-ethylhexanoate in 2-ethylhexanol were placed in the reactor. The hydroformation was carried out continuously over 168 hours. The further reaction parameters as well as conversion and selectivities are shown in Table 1.

Table 1

Raffinate II hydroformylation with an organic Rh / TPP solution (1st stage)

2nd stage

Implementation of the exhaust gas resulting from the first stage (hereinafter referred to as raffinate III) with a composition of 38.8% by volume Butanes, 3.9% by volume 1-butene and 57% by volume cis and trans 2-butenes with 2.7- Bis (3,3-dimetyl-butyl) -9,9-dimethyl-4,5-bis- (2,7-dimethyl-10-phenoxa-phos phino) -xanthene (II) as a diphosphine ligand

A 1 l stainless steel autoclave equipped with a stirrer was supplied with 80 g / h of raffinate III of the above-mentioned composition and 60 Nl / h of CO / H ₂ mixture consisting of equal parts by volume so that 10 Nl / h of exhaust gas could be removed from the reactor , At the same time, 1000 g of the catalyst solution were circulated through the reactor per hour.

The rhodium 2-ethylhexanoate used and 2,7-bis (3,3-dimetyl-butyl) - 9,9-dimethyl-4,5-bis- (2,7-dimethyl-10-phenoxa-phosphino) xanthene previously dissolved in 1000 g Texanol® from Eastman and 500 g valeraldehyde and presented in the reactor. The hydroformation was also fully maintained performed over 168 hours. The other reaction parameters as well as conversion and selectivities are shown in Table 2.

Table 2

Hydroformylation of the reaction gas of the 1st stage in the presence of the diphosphine (II) (2nd stage)

Comparative Example 1

In the first stage, raffinate II was hydroformylated analogously to the first stage of Example 1 according to the invention. The resulting exhaust gas with a composition of 38% by volume of butanes, 3.9% by volume of 1-butene and 57% by volume of cis and trans 2-butenes was then batch-processed in the second stage under unmodified high-pressure conditions at 250 bar and hydroformylated at 160 ° C. Rhodium-2-ethylhexa noate served as the rhodium source and was pumped into the system as a concentrated solution (rhodium content approx. 5000 ppm in 2-ethylhexanol). The concentration of rhodium based on the olefin used was 5 ppm. The reaction was run until conversion was complete and the resulting aldehyde mixture was worked up by distillation. With a conversion of 98%, a C ₅ - aldehyde mixture with an n: i ratio of 45:55 resulted.

The combination of the hydroformylation products from the comparative example 1 gave a pentanal mixture with an n: i ratio of 76:24.

How to compare the results of the method according to the invention with Based on the results of the comparative examples, a butene-II Ge mix according to the two-step procedure according to the invention with a we implement significantly higher selectivity to the straight-chain aldehydes than according to the well-known way of working, in which in the second stage after the known unmodified process works under high pressure. The invent diphosphines used in accordance with the invention are also distinguished by a high catalyst life.

Claims (26)

1. A process for the hydroformylation of olefinically unsaturated compounds, the reaction in a first reaction stage in a homogeneous reaction system using organic phosphorus (III) compounds in complex bonds containing rhodium compounds as catalysts at pressures of 0.2 to 20.0 MPa and Exhaust gas is formed, characterized in that the exhaust gas of the first reaction stage is fed to a second reaction stage in which amounts of the olefinically unsaturated compounds present in the exhaust gas in a homogeneous reaction system in the presence of complex compounds of rhodium and diphosphines of the general formula (I)
in which R ¹ and R ^{2 are} each the same or different (C ₁ -C ₁₈ ) alkyl radicals, (C ₆ -C ₁₄ ) aryl radicals, (C ₇ -C ₂₄ ) aralkyl radicals or (C ₇ -C ₂₄ ) alkylaryl radicals,
R ^{3 represents} hydrogen or a radical -CHR ^a R ^b , in which R ^a and R ^{b are} each the same or different hydrogen, (C ₁ -C ₁₈ ) alkyl, (C ₁ -C ₈ ) alkoxy radicals, unsubstituted or with (C ₁ -C ₁₀ ) alkyl and / or (C ₁ -C ₁₀ ) alkoxy radicals substituted (C ₆ -C ₁₄ ) aryl radicals or (C ₇ -C ₂₄ ) aralkyl radicals Are residues, and R ^{4 is} (C ₁ -C ₁₀ ) alkyl residues, (C ₆ -C ₁₄ ) aryl residues, (C ₇ -C ₂₄ ) aralkyl residues or (C ₇ -C ₂₄ ) - Represent alkylaryl residues, who are implemented at pressures of 0.2 to 20 MPa. 2. The method according to claim 1, characterized in that in the general formula IR ¹ and R ^{2 in} each case the same or different (C ₁ -C ₁₂ ) alkyl radicals, (C ₆ -C ₁₀ ) aryl radicals (C Are ₇ -C ₁₀ ) aralkyl radicals or (C ₇ -C ₁₀ ) alkylaryl radicals,
R ^{3 represents} hydrogen or a radical -CHR ^a R ^b , in which R ^a and R ^{b are} each the same or different hydrogen, (C ₁ -C ₁₂ ) alkyl, (C ₁ -C ₄ ) alkoxy radicals, unsubstituted or with (C ₁ -C ₈ ) alkyl and / or (C ₁ -C ₄ ) alkoxy radicals substituted (C ₆ -C ₁₀ ) aryl radicals or (C ₇ -C ₁₀ ) aralkyl radicals Are residues, and R ^{4 is} (C ₁ -C ₈ ) alkyl residues, (C ₆ -C ₁₀ ) aryl residues, (C ₇ -C ₁₀ ) aralkyl residues or (C ₇ -C ₁₀ ) - Represent alkylaryl radicals. 3. The method according to claim 1 or 2, characterized in that the aryl radical is in each case the phenyl or naphthyl radical and the aralkyl Rest is the benzyl residue. 4. The method according to one or more of claims 1 to 3, characterized in that R ¹ and R ^{2 are the} same or different and methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tertiary butyl, n -Pentyl, i-pentyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl , Tolyl or benzyl mean that
R ³ for methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, n-pentyl, i-pentyl, 3,3-dimethylbutyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl , n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl, tolyl or benzyl and that
R ^{4 is} methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tertiary butyl, n-pentyl, i-pentyl, 3,3-dimethylbutyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl, i-decyl, phenyl, naphthyl, tolyl or benzyl. 5. The method according to any one of claims 1 or 2, characterized in that the diphosphines 2,7-bis (3,3-dimethylbutyl) -9.9-dimethyl-4,5-bis (2,7-dimethyl-10- phenoxaphosphino) xanthene (II), 2,7,9-trimethyl-9-n-nonyl-4,5- bis (2,7-dimethyl-10-phenoxaphosphino) xanthene (III), 2,7-di-n- decyl-9,9-di methyl-4,5-bis (2,7-dimethyl-10-phenoxaphosphino) xanthene (IV), 2,7-di-n-hexyl-9,9-dimethyl-4,5- bis (2,7-dimethyl-10-phenoxaphosphino) xanthene (V), 2,7- (3,3-dimethylbutyl) -9,9-dimethyl-4,5-bis [2,7-di (3.3 -dimethylbutyl) -10- phenoxaphosphino] xanthene (VI), 2,7-dimethyl-9,9-dimethyl-4,5-bis [2,7-di (3,3-dimethylbutyl) -10-phenoxaphosphino] xanthene ( VII) used. 6. The method according to one or more of claims 1 to 5, characterized ge indicates that the hydroformylation in the first reaction stage Temperatures from 50 to 160 ° C and a rhodium concentration of 1 to 1000 ppm by weight, based on the homogeneous reaction mixture, takes place and the molar ratio of rhodium to phosphorus in the homogeneous reactor mixture 1: 1 to 1: 1000. 7. The method according to one or more of claims 1 to 6, characterized ge indicates that the pressure in the first reaction stage is 1 to 12 MPa is preferably 1 to 7 MPa.   8. The method according to one or more of claims 1 to 7, characterized ge indicates that the temperature in the first reaction stage 60 to 150 ° C. and in particular is 75 to 140 ° C. 9. The method according to one or more of claims 1 to 8, characterized ge indicates that the concentration of rhodium in the homogeneous Re action mixture 10 to 700 ppm by weight and in particular 25 to 500 ppm by weight ppm is. 10. The method according to one or more of claims 1 to 9, characterized characterized in that the molar ratio of rhodium to phosphorus in the homogeneous reaction mixture 1: 3 to 1: 500, preferably 1:50 to 1 300. 11. The method according to one or more of claims 1 to 10, characterized characterized in that as organic phosphorus (III) compounds ali phatic, aromatic or mixed aliphatic-aromatic phosphines, Diphosphines or phosphites are used. 12. The method according to one or more of claims 1 to 11, characterized characterized in that the hydroformyation reaction in the second Re Action level at temperatures from 50 to 160 ° C and a rhodium concentration tration from 1 to 1000 ppm by weight, based on the homogeneous reaction gene mix, and the molar ratio of rhodium to phosphorus im Reaction mixture is 1: 1 to 1:80. 13. The method according to one or more of claims 1 to 12, characterized characterized in that the pressure in the second reaction stage 1 to 12 MPa, is in particular 1 to 5 MPa.   14. The method according to one or more of claims 1 to 13, characterized characterized in that the temperature in the second reaction stage 60 to 150 ° C and in particular 75 to 140 ° C. 15. The method according to one or more of claims 1 to 14, characterized characterized in that the rhodium concentration in the second reaction level 50 to 500 ppm by weight and in particular 100 to 300 ppm by weight, bezo gene to the homogeneous reaction mixture. 16. The method according to one or more of claims 1 to 15, characterized characterized in that the molar ratio in the second reaction stage of rhodium to phosphorus in the reaction mixture is 1: 1 to 1:20. 17. The method according to one or more of claims 1 to 16, characterized characterized in that the first and second hydroformylation in a solvent, using paraffin oil as the solvent, aromatic hydrocarbons, ethers, aldehydes, ketones or higher Ending condensation products of aldehydes, especially trimers of Aldehydes. 18. The method according to one or more of claims 1 to 17, characterized characterized in that the olefinically unsaturated compounds are olefinic unsaturated compounds with internal double bonds or Gemi containing olefinically unsaturated compounds with internal Double bonds used. 19. The method according to claim 18, characterized in that one olefi nically unsaturated compounds with 4 to 12 carbon atoms are used. 20. The method according to claim 19, characterized in that the olefinic unsaturated compound is a mixture containing butene-1 and butene-2.   21. Process for the preparation of carboxylic acids from olefinically unsaturated Compounds, characterized in that the olefinically unsaturated Compound according to one or more of claims 1 to 20 hydrofor mylated, the aldehyde mixtures obtained from the hydroformylation stages separates and unites and subsequently in a known manner to Car oxidized bonic acids. 22. Process for the preparation of alcohols from olefinically unsaturated Compounds, characterized in that the olefinically unsaturated Compound according to one or more of claims 1 to 20 hydrofor mylated, the aldehyde mixtures obtained from the hydroformylation stages separated and combined and subsequently in a manner known per se to Al alcohol reduced or hydrogenated. 23. Process for the preparation of amines from olefinically unsaturated ver Bonds, characterized in that the olefinically unsaturated Compound according to one or more of claims 1 to 20 hydrofor mylated, the aldehyde mixtures obtained from the hydroformylation stages separated and combined and subsequently in the presence of an Aminierungska talysators and hydrogen with ammonia, a primary or secondary Amine aminated in a manner known per se. 24. Process for the preparation of mixtures of isomeric decyl alcohols Mixtures containing butene-1 and butene-2, characterized in that that the mixture containing butene-1 and butene-2 according to one or more of claims 1 to 17 hydroformylated, the aldehyde obtained mixtures separated from the hydroformylation stages and combined, the ver condensed aldehyde mixtures to form an aldol mixture, separates the aldol mixture and to a mixture of isomeric decyl alcohols hydrogenated.   25. Process for the production of didecyl phthalate from butene-1 and butene-2 containing mixtures, characterized in that the butene-1 and mixture containing butene-2 according to one or more of the claims che 1 to 17 hydroformylated, the aldehyde mixtures obtained from the Hydroformylation stages separated and combined, the combined aldehyde mix condensed to form an aldol mixture, the aldol mixture separated and hydrogenated to a mixture of isomeric decyl alcohols and that Mixture of isomeric decyl alcohols with phthalic acid or phthalic anhydride esterified. 26. Process for the preparation of mixtures of isomeric decan carboxylic acids from mixtures containing butene-1 and butene-2, characterized in that that the mixture containing butene-1 and butene-2 according to one or several of claims 1 to 17 hydroformylated, the aldehyde obtained mixtures separated from the hydroformylation stages and combined, the ver condensed aldehyde mixtures to form an aldol mixture, partially separates the aldol mixture to a mixture of isomeric decanals hydrogenated and then to a mixture of isomeric decane carboxylic acids oxidized.