A process for the preparation of a dialdehyde

Abstract

The application provides a preparation method of dialdehyde, comprising the following steps: S1: under the action of a catalyst, carrying out hydroformylation reaction on non-conjugated diene with carbon-carbon double bond alkenyl and allyl alcohol group at the end of each molecule respectively, carbon monoxide and hydrogen in an aqueous phase to generate a reaction mixture; S2: carrying out extraction on the reaction mixture obtained in step S1; S3: carrying out at least twice rectification on the dialdehyde-containing extraction oil phase obtained in step S2 to obtain a dialdehyde product. The application has the beneficial effects that the preparation method of dialdehyde has the characteristics of low catalyst cost, mild reaction condition, high catalytic activity, low product separation cost, obvious energy consumption advantage and high production efficiency, can realize raw material conversion rate of 95-99%, dialdehyde selectivity of 95-99% and n-iso ratio of 8.5-24:1.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of compound synthesis, and particularly relates to a preparation method of dialdehyde. BACKGROUND

[0002] Long carbon chain dialdehyde is a key intermediate for preparing long carbon chain nylon, long carbon chain polyester and polyurethane. Taking 1,9-nonanedial as an example, its downstream products include 1,9-nonanediamine, 1,9-nonanediol, 1,9-nonanedioic acid, nylon 9T, polyester polyol based on nonanediol, polyurethane epoxy resin, UV light curing monomer, essence and perfume, etc.

[0003] The current disclosed long carbon chain dialdehyde (taking 1,9-nonanedial as an example) synthesis process includes the following several kinds:

[0004] I. Oleic acid decomposition method

[0005] This method is to make oleic acid undergo ozone decomposition and esterification to obtain nonanedioate ester, and then use lithium aluminum hydride as a reducing agent to perform partial reduction, and finally obtain nonanedial. However, this method has the disadvantages of high cost of raw materials and reducing agent, incomplete reduction depth, etc., and therefore is impractical from a commercial point of view.

[0006] II. Hydroformylation of 7-octene-1-al

[0007] CN105050996A and EP1489087A respectively disclose the hydroformylation reaction of 7-octene-1-al and hydrogen, carbon monoxide catalyzed by a catalyst composed of rhodium and a biphosphine ligand, and the selectivity of 1,9-nonanedial and 2-methyl-1,8-octanedial obtained is 80-92% and 5-16% respectively, and the normal / iso ratio is 4-6:1. However, the recycling ability of the above-mentioned catalyst system is not disclosed in the above-mentioned patents. CN101415717A discloses the hydroformylation reaction of 2,7-octadiene-1-methyl ether as a raw material catalyzed by a rhodium-biphosphine catalyst, and due to the presence of the methoxy group, only the terminal double bond hydroformylation product with a yield of more than 90% can be obtained.

[0008] Since the rhodium catalyst is very expensive, as a hydroformylation catalyst used in industry, it is desired that the amount of the catalyst used is as little as possible, and at the same time, the catalyst needs to be recovered with a high recovery rate for recycling. Compared with low-carbon olefins such as propylene, long carbon chain non-conjugated dienes and their hydroformylation products have very high boiling points. In order to separate the rhodium catalyst from the product by distillation, the reaction mixture must be heated to a high temperature until the long carbon chain dialdehyde product with a high boiling point is distilled. In this process, the rhodium catalyst is prone to thermal decomposition, resulting in the formation of rhodium clusters and metal precipitation, and the degradation and oxidation of the catalyst to form high-boiling-point compounds, so that the catalyst is difficult to be reused by recycling for a long enough time, resulting in a sharp increase in cost.

[0009] CN1538971A discloses a process for the hydroformylation of 7-octene-1-al in the presence of rhodium, a water-soluble phosphine ligand having a sulfonic acid group and polyethylene glycol, and then adding water to the reaction solution to separate the catalyst components by extraction, removing the water from the separated water layer, and recycling the obtained polyethylene glycol containing the catalyst components to the hydroformylation reactor, while obtaining 1,9-nonanedial from the organic layer. However, according to the information disclosed in this patent, the molar ratio of the ligand to Rh used in the reaction is high (80:1), and the normal / iso ratio in the reaction product is only 4-5:1. In addition, although the Rh recovery rate in this process is 97-98%, the ligand recovery rate is only 82-83%, and the phosphine ligand needs to be replenished regularly. As is well known, the cost of the phosphine ligand is also very high, which will inevitably increase the operating cost of the device and reduce its technical competitiveness.

[0010] III. Hydroformylation of 2,7-octadiene-1-ol

[0011] US4420640A discloses the synthesis of 1,9-nonadienal by hydroformylation of 2,7-octadien-1-ol using rhodium and triphenylphosphine as catalyst. This technology directly obtains 1,9-nonadienal from 2,7-octadien-1-ol without isomerization to prepare 7-octen-1- aldehyde. However, from the information disclosed in the patent, the process has the following problems: ① the selectivity of 1,9-nonadienal generated by the reaction is only 18-43%, the main product is mainly 9-hydroxy-7-octen-1-al (the terminal allyl alcohol group is not isomerized to aldehyde), the selectivity is 51-76%, and the rest of the by-products are 9-hydroxy-6-nonenal, 8-hydroxy-2-methyl-6-octenal, 2-methyl-1,8-octadienal, 2,6-octadien-1-ol and n-octanol, etc. Although the patent mentions that 9-hydroxy-7-octen-1-al can be isomerized to 1,9-nonadienal by copper-chromium catalyst, but in the research process of the inventors, it is found that 9-hydroxy-7-octen-1-al is extremely unstable when isomerized by copper-chromium catalyst at high temperature, and is extremely easy to form various by-products such as acetal and internal double bond migration, and their structures and boiling points are extremely close, which is difficult to separate by conventional rectification means, which also leads to a complex industrialization device and a high purification cost, thereby reducing the product competitiveness; ② the patent uses high-boiling 1,10-decanediol diacetate and dioctyl phthalate as solvent, and the product still uses conventional rectification means for separation, which still cannot avoid the occurrence of rhodium catalyst metal precipitation and thermal degradation during high-temperature rectification, and further due to the accumulation of high-boiling by-products, the catalytic activity of the catalyst will be reduced. Therefore, the cost of the catalyst inevitably accounts for a large part of the production cost. And the patent does not disclose the recycling of the catalytic system.

[0012] In order to overcome the limitations of the prior art, the following problems need to be solved: ① achieve high reaction rate from the acceptable rhodium catalyst concentration of industrialization cost; ② obtain high selectivity to 1,9-nonadienal, reduce as much as possible the occurrence of other isomerization including double bond migration and other side reactions, and reduce the separation difficulty of the reaction product; ③ maintain the activity of rhodium catalyst for a long time; ④ effectively separate 1,9-nonadienal from the reaction mixture without significantly reducing the activity of rhodium catalyst; ⑤ improve the recovery rate of rhodium catalyst and its ligand, and effectively reduce the use cost of the catalyst. SUMMARY

[0013] In view of the above, the present application aims to provide a method for preparing a dialdehyde, in order to solve the above technical problems. The method for preparing a dialdehyde includes the following steps: S1, carrying out hydroformylation of a non-conjugated diene having carbon atoms of 6-12 and having an olefin group and an allyl alcohol group at each molecular end, in the presence of a catalyst, carbon monoxide and hydrogen in an aqueous phase, to obtain a reaction mixture; S2, carrying out extraction on the reaction mixture obtained in step S1, and recycling the raffinate aqueous phase containing the catalyst obtained after the extraction to the hydroformylation reaction step S1; and S3, carrying out rectification on the dialdehyde-containing extract oil phase obtained in step S2 at least twice, to obtain a dialdehyde product.

[0014] To achieve the above object, the technical scheme of the present application is as follows:

[0015] A method for preparing a dialdehyde, including the following steps:

[0016] S1, carrying out hydroformylation of a non-conjugated diene having carbon atoms of 6-12 and having an olefin group and an allyl alcohol group at each molecular end, in the presence of a catalyst, carbon monoxide and hydrogen in an aqueous phase, to obtain a reaction mixture;

[0017] S2, carrying out extraction on the reaction mixture obtained in step S1, and recycling the raffinate aqueous phase containing the catalyst obtained after the extraction to the hydroformylation reaction step S1;

[0018] S3, carrying out rectification on the dialdehyde-containing extract oil phase obtained in step S2 at least twice, to obtain a dialdehyde product.

[0019] The catalyst in step S1 is a ligand and at least one compound of a transition metal of group VIII, wherein the ligand comprises at least one compound selected from the general formula (I);

[0020]

[0021] In the formula, R

[0022] R 1 , R 2 , R 3 , R 4 is hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, COOR a , COO - M + , SO3R a , SO3-M + , NE 1 E 2 , alkylene-NE 1 E 2 , NE 1 E 2 E 3+ X - , alkylene NE 1 E 2 E 3+ X - , OR a , SR a, halogen, trifluoromethyl, nitro, acyl and cyano; R 1 , R 2 , R 3 , R 4 are identical or different radicals;

[0023] wherein R a , E 1 , E 2 and E 3 are identical or different radicals, R a , E 1 , E 2 and E 3 are any of hydrogen, alkyl, cycloalkyl or aryl; M + is a cation, X - is an anion;

[0024] Preferably, M + comprises Li + , Na + , K + or any of the cations HN + F 1 F 2 F 3 , wherein F 1 , F 2 and F 3 are identical or different radicals, F 1 , F 2 and F 3 are any of hydrogen, alkyl, cycloalkyl or aryl;

[0025] X - comprises any of fluoride, chloride or bromide;

[0026] A 1 , A 2 are any of O, S, SiR b R c , NR d or CR 5 R 6 , A 1 , A 2 are identical or different radicals;

[0027] wherein R b , R c , R d , R 5 and R 6 are each independently any of hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or heteroaryl;

[0028] R7 R 8 R 9 R 10 It is any one of substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or heteroaryl;

[0029] R 7 R 8 R 9 R 10 The substituents on them are the same or different;

[0030] Preferably, R 7 R 8 R 9 R 10 It has one, two, or three substituents, said substituents being substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl, COOR f COO - U + SO3 - R f SO3U + NE 4 E 5 Alkylene-NE 4 E 5 NE 4 E 5 E 6+ V - Alkylene NE 4 E 5 E 6+ V - OR f SR f Any one of halogen, trifluoromethyl, nitro, acyl, and cyano groups; U + V- is a cation, and V- is an anion;

[0031] Preferably, U + Including Li + Na + K + or cation HN + F 1 F 2 F 3 Any one of them, where F 1 F 2 and F 3 Are they the same or different groups, F 1 F 2 and F 3is any one of hydrogen, alkyl, cycloalkyl or aryl;

[0032] V - is any one of fluoride ion, chloride ion or bromide ion;

[0033] wherein R f , E 4 , E 5 , E 6 are identical or different radicals, R f , E 4 , E 5 , E 6 is any one of hydrogen, alkyl, cycloalkyl or aryl.

[0034] Further, the Group VIII transition metal element in the Group VIII transition metal compound is selected from one or both of rhodium and palladium;

[0035] Preferably, the Group VIII transition metal element in the Group VIII transition metal compound is rhodium or palladium, wherein the molar ratio of palladium atom to rhodium atom is (0.01-0.5):1;

[0036] Preferably, the non-conjugated diene is an allyl alcohol group having 6-12 carbon atoms.

[0037] Preferably, the molar ratio of the rhodium atom to the non-conjugated diene raw material having an olefin group and an allyl alcohol group at the molecular terminal, respectively, is (0.00001-0.01):1.

[0038] Further, the ligand is a compound of general formula (I-1) or general formula (I-2);

[0039]

[0040] wherein:

[0041] R 1 , R 3 is any one of hydrogen, C1-C4 alkyl, C5-C8 cycloalkyl, aryl, heteroaryl, OR a , SR a , halogen, trifluoromethyl, nitro, acyl and cyano, R 1 and R 3 are identical or different radicals;

[0042] R a is any one of hydrogen, alkyl, cycloalkyl or aryl;

[0043] A 1 is O, S or CR 5 R 6 is any one of hydrogen, C1-C4 alkyl, C5-C8 cycloalkyl, aryl, heteroaryl, OR5 R 6 is any one of hydrogen, C1-C4alkyl, R 5 R 6 are identical or different radicals;

[0044] R 11 R 12 R 13 R 14 is any one of hydrogen, substituted or unsubstituted C1-C4alkyl, substituted or unsubstituted C5-C8cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; R 11 R 12 R 13 R 14 are identical or different radicals;

[0045] Preferably, R 11 R 12 R 13 R 14 carry one, two or three substituents, which include alkyl, cycloalkyl, heterocycloalkyl, aryl or heteroaryl, COOR f COO - Y + SO3 - R f SO3Y + NE 4 E 5 alkylene-NE 4 E 5 NE 4 E 5 E 6+ Z - alkyleneNE 4 E 5 E 6+ Z - OR f SR f halogen, trifluoromethyl, nitro, acyl and cyano;

[0046] wherein R f E 4 E 5 and E 6 are identical or different radicals, each selected from any one of hydrogen, alkyl, cycloalkyl or aryl;

[0047] R 11 R 12 R 13 R 14 the substituents on R

[0048] Z - is an anion, Y + is a cation, Y + is Li + , Na + , K + or a cation HN + F 1 F 2 F 3 , wherein F 1 , F 2 and F 3 are identical or different radicals, F 1 , F 2 and F 3 are any of hydrogen, alkyl, cycloalkyl or aryl.

[0049] Z - comprises any of fluoride, chloride or bromide.

[0050] Further, each molecule in the step S1 has a carbon atom number of 6-12 of the non-conjugated diene raw material having a carbon-carbon double bond alkenyl group and an allyl alcohol group at each end, respectively;

[0051] Preferably, the non-conjugated diene comprises one of 2,5-hexadiene-1-ol, 2,6-heptadiene-1-ol, 2,7-octadiene-1-ol, 2,8-nonadiene-1-ol, 2,9-decadiene-1-ol.

[0052] Further, the hydroformylation reaction involved in the step S1 is carried out in an aqueous phase, the aqueous phase comprising a water-soluble solvent and water;

[0053] The water-soluble solvent comprises one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, acetone, tetrahydrofuran, dioxane, heptanone, sulfolane, polyethylene glycol, polyethylene glycol dimethyl ether; and / or

[0054] The content of water in the aqueous phase is 25-60wt%.

[0055] Further, an organic tertiary amine is added in the hydroformylation reaction in the step S1, the mass of the added organic tertiary amine being 0.1-10wt% of the mass of the non-conjugated diene;

[0056] Preferably, the organic tertiary amine includes one or more of trialkylamine, trialkanolamine, alicyclic tertiary amine, pyridine; the organic tertiary amine plays the following roles: ① accelerates the catalytic cycle of rhodium and palladium, and improves the reaction rate of hydroformylation reaction; ② promotes the further isomerization of terminal allyl group in the raw material molecule into aldehyde under the catalysis of palladium, so as to obtain a dialdehyde product; ③ prevents the formation of acetal due to the presence of trace acid during the reaction.

[0057] Preferably, the reaction temperature of the hydroformylation reaction is 40-150℃, the molar ratio of the mixed gas H2 / CO of hydrogen and carbon monoxide is 0.1-10, and the reaction pressure is 0.1-10 MPa.

[0058] Further, the step S2 includes extracting the reaction mixture obtained from the step S1 with a saturated aliphatic hydrocarbon or a saturated alicyclic hydrocarbon, and separating it into an extracted oil phase containing dialdehyde and a raffinate water phase;

[0059] Preferably, the saturated aliphatic hydrocarbon includes at least one of n-pentane, n-hexane, n-octane;

[0060] Preferably, the saturated alicyclic hydrocarbon includes at least one of cyclopentane, cyclohexane, methylcyclohexane, decalin, and ether, wherein the ether is selected from any one of dibutyl ether, diisopropyl ether, ethyl phenyl ether, and methyl tert-butyl ether.

[0061] Preferably, the extraction separation in the step S2 is carried out in an inert atmosphere gas, the extraction temperature is 20-80℃, and the extraction pressure is 0.1-5 MPa.

[0062] Preferably, the inert atmosphere gas includes one or more of helium, neon, argon, krypton, xenon, or nitrogen.

[0063] The product prepared by using the above method includes one of linear alkanedial and methyl alkanedial.

[0064] Preferably, the linear alkanedial includes one of 1,7-heptanedial, 1,8-octanedial, 1,9-nonanedial, 1,10-decanedial, and 1,11-undecanedial.

[0065] Preferably, the methyl alkanedial includes one of 2-methyl-1,6-hexanedial, 2-methyl-1,7-heptanedial, 2-methyl-1,8-octanedial, 2-methyl-1,9-nonanedial, and 2-methyl-1,10-decanedial.

[0066] As specific examples of the general formula (I), compounds represented by, but not limited to, the following structures can be listed:

[0067]

[0068]

[0069]

[0070] The step S1 of the present application provides a catalyst comprising at least one ligand selected from the group consisting of compounds of general formula (I) and at least one Group VIII transition metal compound, wherein the Group VIII transition metal compound is selected from rhodium. The rhodium compound can be selected from the group consisting of Rh(NO3)2, Rh(OAc)2, Rh(acac)(CO)2, Rh(acac)(CO)(PPh3), HRh(CO)(PPh3)3, RhCl(CO)(PPh3)2, RhBr(CO)(PPh3)2, RhCl(PPh3)3, [Rh(μ-OAc)(CO)2]2, [Rh(μ-OAc)(COD)]2, [Rh(μ-Cl)(COD)]2, [Rh(μ-Cl)(CO)2]2, Rh4(CO) 12 8(PPh3)4, and Rh6(CO) 16 (wherein OAc represents acetyl, acac represents acetylacetonate, Ph represents phenyl, and COD represents 1,5-cyclooctadiene). Of these, Rh(acac)(CO)2and Rh(OAc)2are preferred from the viewpoint of being able to easily prepare a rhodium catalyst under an atmosphere of a mixed gas comprising carbon monoxide and hydrogen.

[0071] The step S1 of the present application provides a catalyst comprising at least one ligand selected from the group consisting of compounds of general formula (I) and at least one Group VIII transition metal compound, wherein the Group VIII transition metal compound is selected from rhodium. The rhodium compound can be selected from the group consisting of Rh(NO3)2, Rh(OAc)2, Rh(acac)(CO)2, Rh(acac)(CO)(PPh3), HRh(CO)(PPh3)3, RhCl(CO)(PPh3)2, RhBr(CO)(PPh3)2, RhCl(PPh3)3, [Rh(μ-OAc)(CO)2]2, [Rh(μ-OAc)(COD)]2, [Rh(μ-Cl)(COD)]2, [Rh(μ-Cl)(CO)2]2, Rh4(CO)

[0072] Further, the molar ratio of the rhodium atom to the non-conjugated diene hydrocarbon raw material having carbon-carbon double bond alkenyl and allyl alcohol groups at each molecular end, each having 6 to 12 carbon atoms, in step S1 is (0.00001 to 0.01): 1, preferably (0.0001 to 0.005): 1, and particularly preferably (0.0001 to 0.001): 1; the molar ratio of palladium to rhodium is (0.01 to 0.5): 1, and preferably (0.05 to 0.2): 1; and the amount of the water-soluble phosphine ligand represented by the general formula (I) is in the range of 10 to 200 moles per gram atom of rhodium, preferably 10 to 100 moles, and more preferably 15 to 80 moles.

[0073] The present inventors have unexpectedly found that the addition of a small amount of palladium to a rhodium catalyst forms a Rh-Pd bimetallic complex that exhibits high synergistic catalytic action in a catalytic hydroformylation reaction, and that a higher reaction selectivity and n / iso ratio can be obtained. In addition, in the presence of a small amount of an organic tertiary amine additive, the palladium can further catalyze the isomerization of the terminal allyl group in the raw material molecule to an aldehyde, thereby obtaining a dialdehyde product.

[0074] In step S1 of the present application, for the preparation of a catalyst comprising at least one ligand represented by the general formula (I) and at least one Group VIII transition metal compound, at least one Group VIII transition metal compound, i.e., a rhodium and palladium compound, can be dissolved in a solvent and the solution supplied to the hydroformylation reaction system, and a solution of the ligand represented by the general formula (I) dissolved in a solvent can be supplied to the hydroformylation reaction system, and the catalyst formed in the reaction system; or the rhodium and palladium compound and the ligand represented by the general formula (I) can be dissolved in a solvent under an inert gas atmosphere, and the solution of the catalyst prepared by stirring under an inert gas atmosphere, preferably under a nitrogen, argon, helium or the like inert gas or a mixed gas atmosphere comprising carbon monoxide and hydrogen, and then supplied to the hydroformylation reaction system.

[0075] The non-conjugated diene hydrocarbon raw material having carbon-carbon double bond alkenyl and allyl alcohol groups at each molecular end, each having 6 to 12 carbon atoms, in step S1 of the present application is selected from any of 2,5-hexadien-1-ol, 2,6-heptadien-1-ol, 2,7-octadien-1-ol, 2,8-nonadien-1-ol, 2,9-decadien-1-ol, and preferably 2,7-octadien-1-ol. The raw material 2,7-octadien-1-ol used in the hydroformylation reaction of the present application can be prepared by any method. Preferably, 2,7-octadien-1-ol having a purity of about 90 to 99.9%, and particularly preferably about 95 to 99.9%, is used.

[0076] Further, the amount of the organic tertiary amine is 0.1-10 wt%, preferably 0.2-5 wt%, and particularly preferably 0.5-3 wt% of the raw material. The organic tertiary amine has the following functions: ① accelerating the catalytic cycle of rhodium and palladium and increasing the reaction rate of the hydroformylation reaction; ② promoting the further isomerization of the terminal allyl group in the raw material molecule into aldehyde by palladium catalysis, thereby obtaining the dialdehyde product; and ③ preventing the formation of acetals due to the presence of trace amounts of acid during the reaction.

[0077] The reaction temperature of the hydroformylation reaction of step S1 is 40-150°C, preferably 50-120°C, and particularly preferably 60-100°C, from the perspective of inhibiting catalyst deactivation.

[0078] The hydroformylation reaction can be carried out continuously, semi-continuously or intermittently, and is preferably carried out continuously.

[0079] In the process of the present application, the dialdehyde-containing reaction mixture obtained in step S1 is subjected to extraction in the next step S2. As the extraction device, a general-purpose extraction device such as an extraction column or a centrifugal extractor can be used.

[0080] Further, in order to achieve efficient extraction of the dialdehyde product and minimize the dissolution or migration of catalyst components, water-soluble solvents and auxiliary organic tertiary amines in the extraction layer, the amount of the extractant is 0.3-3 times the volume of the reaction mixture of step S1, and preferably 0.5-2 times the volume. If the amount of the extractant is too low, the extraction rate of the desired product is too low; on the other hand, if the amount of the extractant exceeds 3 times the volume of the reaction mixture, a large amount of extractant must be recovered when the product is separated, which inevitably increases the energy consumption for separation and is not economical in industry.

[0081] The extraction separation temperature in step S2 of the present application is 20-80°C, and preferably 30-60°C. A temperature that is too low reduces the efficiency of dialdehyde product extraction; although there is no upper limit to the extraction temperature, the extraction temperature is generally not higher than the reaction temperature of step S1, considering the relationship between temperature and the pressure of the mixed gas of inert gas and / or hydrogen and carbon monoxide in the extraction system. The extraction separation is preferably carried out in an inert gas, such as nitrogen, helium, argon, carbon dioxide, etc., which does not adversely affect the extraction process, and is preferably carried out in a mixed gas of hydrogen and carbon monoxide, the molar ratio of which is 0.1-10, and preferably 1-3. The extraction separation pressure is 0.1-5 MPa, and preferably 0.1-2 MPa. The extraction separation is preferably carried out continuously, or can be carried out by batchwise operation.

[0082] In the extraction process of step S2, the dialdehyde product and unreacted raw material are extracted into the extraction layer (oil phase), while the catalyst component, water-soluble solvent, and organic tertiary amine auxiliary are separated into the raffinate layer (water phase). In a preferred embodiment of the present application, a small amount of water is added to the extraction layer for back extraction, which can further effectively extract a small amount of catalyst component and organic tertiary amine auxiliary dissolved or migrated in the original extraction layer, thereby improving the recovery rate of the catalyst and organic tertiary amine auxiliary. The back-extracted water phase can be combined with the raffinate layer and recycled to the hydroformylation reaction step S1 as it is or after a known catalyst activation procedure, i.e., the step S2 recycling step of the present application. The extraction layer is subjected to rectification at a liquid phase temperature of not higher than 100°C. The low-boiling-point extraction solvent rectified out can be reused for the extraction operation of step S2. Further rectification of the rectification residue can obtain the dialdehyde product with a purity of greater than 99%.

[0083] The dialdehyde product with each molecular end having an aldehyde group and a carbon atom number of 7-13 according to the present application is selected from linear alkanedial, such as 1,7-heptanedial, 1,8-octanedial, 1,9-nonanedial, 1,10-decanedial, 1,11-undecanedial, etc.; methylalkanedial, such as 2-methyl-1,6-hexanedial, 2-methyl-1,7-heptanedial, 2-methyl-1,8-octanedial, 2-methyl-1,9-nonanedial, 2-methyl-1,10-decanedial, preferably 1,9-nonanedial and 2-methyl-1,8-octanedial.

[0084] 1,9-Nonanedial can be converted into 1,9-nonanedioic acid by oxidation, which is commercially used as a raw material for producing lubricants, polyesters, and plasticizers, etc.; 1,9-nonanedial can also be converted into 1,9-nonanediol by hydrogenation, which is used for producing long-carbon-chain polyesters and polyurethanes, etc.; in addition, 1,9-nonanedial can be converted into 1,9-nonanediamine by reacting with ammonia and hydrogen, which is used for producing long-carbon-chain high-temperature nylon, etc.

[0085] Compared with the prior art, the dialdehyde preparation method according to the present application has the following advantages:

[0086] 1. The present application adopts non-conjugated diene with carbon atom number of 6-12, which has carbon-carbon double bond olefin group and allyl alcohol group at each molecular end, as raw material, directly prepares dialdehyde in one step under water-soluble rhodium-palladium catalytic system, and can obtain raw material conversion rate of 95-99%, dialdehyde selectivity of 95-99%, and normal / iso ratio of 8.5-24:1. Taking synthesis of 1,9-nonanedial as an example, the present application directly prepares 1,9-nonanedial by hydroformylation reaction of 2,7-octadien-1-ol as raw material, under the synergistic catalysis of rhodium-palladium bimetallic catalyst, with organic tertiary amine, the other end allyl alcohol group can be directly isomerized to aldehyde while the end olefin hydroformylation is carried out, thereby effectively improving the selectivity (88-92%) and normal / iso ratio (8.5-24:1) of straight-chain 1,9-nonanedial.

[0087] 2. The dialdehyde preparation method of the present application has obvious cost advantage of catalyst use. On one hand, the rhodium-palladium catalyst used in the present application has very low dosage, and the ratio of water-soluble phosphine ligand to rhodium atom is lower than or close to the prior art, which reduces the input cost of catalyst from the source; on the other hand, the water-soluble catalytic system and extraction process used in the present application can realize high recovery rate of noble metal and phosphine ligand in the catalyst, and can maintain the catalytic activity of the catalytic system for a long time. In a preferred embodiment of the present application, the rhodium atom recovery rate is greater than 95%, the palladium atom recovery rate is greater than 96%, and the water-soluble phosphine ligand recovery rate is greater than 95% through the extraction process. After the catalyst is continuously used for 30 cycles, it still maintains high reaction conversion rate and selectivity. This greatly reduces the use cost of the catalyst and improves the technical competitiveness, which is very advantageous for the control of industrialization cost.

[0088] 3. The dialdehyde preparation method of the present application has low separation operation difficulty and low energy consumption. Compared with the prior art, the present application has mild reaction conditions and easy extraction separation operation, and does not need to use high-temperature rectification to recover the catalyst, which avoids the problems of rhodium catalyst metal precipitation and thermal degradation in the high-temperature rectification process, and further effectively maintains the activity of the catalyst for a long time. In addition, the high reaction selectivity and yield can further effectively avoid the generation of high-boiling point by-products such as double bond migration isomerization with similar functional groups and carbon atom numbers, greatly reducing the difficulty and operation difficulty of by-product separation, and having obvious energy consumption advantage, which is suitable for industrial production.

[0089] 4. The dialdehyde preparation method of the present application has strong universality and can be used to prepare various dialdehydes with different carbon atom numbers. DETAILED DESCRIPTION

[0090] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0091] The present application will be described in detail below with reference to Examples. The following Examples are intended to illustrate the present application without limitation.

[0092] In the following Examples, the concentrations of rhodium atoms, palladium atoms and phosphine ligand compounds contained in the aqueous phase obtained by the extraction operation were analyzed and quantified by an Agilent inductively coupled plasma mass spectrometer. In addition, the organic tertiary amine adjuvant, the raw material and the product dialdehyde contained in the hydroformylation reaction liquid or the aqueous phase containing the catalyst were analyzed and quantified by gas chromatography under the following measurement conditions. On this basis, the conversion rate of the reactants, the selectivity and the yield of the product were calculated.

[0093] The gas chromatography analysis conditions were as follows:

[0094] Chromatographic column: Agilent DB-Wax (specifications: 30 m x 0.32 mm x 0.25 mm); injection port temperature: 300°C; split ratio: 30:1; column flow rate: 1.5 mL / min; column temperature: 100°C for 0.5 min; temperature rising program: 15°C / min to 300°C, hold for 8 min; detector temperature: 300°C, hydrogen flow rate: 35 mL / min, air flow rate: 350 mL / min.

[0095] The preparation of the catalyst was carried out at room temperature, normal pressure and under a nitrogen atmosphere, unless otherwise specified, and the raw materials and solvents were previously distilled and purified, and then used after nitrogen replacement.

[0096] As the water-soluble phosphine ligand represented by general formula (I), the compounds shown in the following chemical formula were used in the hydroformylation reaction in the Examples. These compounds can be synthesized and prepared according to known methods.

[0097]

[0098] Example 1:

[0099] Step S1 hydroformylation reaction:

[0100] Into a 100 mL glass flask, 5 g of a dimethyl sulfoxide solution containing Rh(acac)(CO)2 81.8 mg (rhodium atoms 0.317 mmol) and Pd(acac)2 9.8 mg (palladium atoms 0.032 mmol) was added under a nitrogen atmosphere, followed by the addition of 20 g of an aqueous solution containing 4.96 g (6.34 mmol) of ligand A, and stirring at room temperature for 20 min to prepare catalyst A.

[0101] Into a 500 mL autoclave were introduced 80 g of desalted water, 125 g of dimethyl sulfoxide, 80 g of 2,7-octadien-l-ol (0.634 mol), and 0.8 g of triethylamine, and the autoclave was purged with nitrogen three times and then with a mixed gas of hydrogen and carbon monoxide (molar ratio of hydrogen to carbon monoxide: 1:1) to pressurize the autoclave to 2 MPa. The autoclave was stirred at 500 rpm and heated to 80°C. Subsequently, a solution of the catalyst A prepared in advance was pressurized and fed into the autoclave using a mixed gas of hydrogen and carbon monoxide (molar ratio of hydrogen to carbon monoxide: 1:1) to make the total pressure 2.5 MPa. The time at which the solution of the catalyst A was pressurized and fed into the autoclave was defined as the start of the reaction. Note that the molar ratio of the phosphine ligand A to rhodium atoms in the solution of the catalyst A was 20:1, and the molar ratio of palladium atoms to rhodium atoms was 0.1:1. The molar ratio of rhodium atoms to the starting material 2,7-octadien-l-ol in the hydroformylation reaction was 0.0005:1, and the mass ratio of triethylamine to the starting material was 1 wt%. The water content in the aqueous solvent was 43.5 wt%.

[0102] The hydroformylation reaction solution after a certain period of time was subjected to quantitative analysis of the products by gas chromatography.

[0103] The conversion of the starting material 2,7-octadien-l-ol was calculated according to the following mathematical formula 1. The units of the amounts in the formula are mol.

[0104] As the reaction products, 1,9-nonadienal, 2-methyl-l,8-octadienal, 9-hydroxy-7-nonen-l-al, 9-hydroxy-6-nonen-l-al, 8-hydroxy-2-methyl-6-octen-l-al, 2-methyl-l,8-octadiene aldehyde, 2,6-octadien-l-ol, n-octanol, and the like can be exemplified. The units of the amounts in the formula are mol.

[0105]

[0106] The selectivity of the high-boiling product = 100 - (the sum of the selectivities of the products calculated according to mathematical formula 2) (mathematical formula 3)

[0107] After 3 h of the reaction, the conversion of the starting material 2,7-octadien-l-ol was 98.2%, the selectivity of the product 1,9-nonadienal was 91.5%, the selectivity of 2-methyl-l,8-octadienal was 6.8%, the normal / isomer ratio was 24:1, the selectivity of 9-hydroxy-7-nonen-l-al was 0.4%, and the selectivity of the other components and the high-boiling product was 1.3%.

[0108] Extraction of the reaction solution of Step S2:

[0109] The autoclave was cooled to 30°C, and then the reaction mixture was pumped into a pressure-resistant glass reactor, which was pressurized with a mixture of hydrogen and carbon monoxide (molar ratio 1:1) to 0.3 MPa in advance. 200 mL of cyclohexane was pumped into the glass reactor, the temperature in the reactor was maintained at 30°C, and the mixture was stirred at 0.3 MPa for 20 min. After the stirring was stopped, the reaction mixture was separated into oil and water phases, and after standing for 10 min, the extraction layer (oil phase) was pumped out through a pipe by the internal pressure. The pressure-resistant glass reactor containing the water phase was maintained at 0.3 MPa and 30°C, and 135 mL of fresh cyclohexane was added again. The mixture was stirred at the same conditions for 10 min, and then stood for 5 min. The upper extraction layer was pumped out of the autoclave and combined with the previously removed cyclohexane extraction phase, and finally 5 mL of water was added to it for back extraction, and the water phase was added to the pressure-resistant glass reactor. It should be noted that the volume ratio of cyclohexane to hydroformylation reaction liquid was 1.2:1.

[0110] The rhodium content, palladium content and phosphine ligand content contained in the water phase were calculated by the rhodium concentration, palladium concentration, phosphorus concentration and the weight of the recovered water phase, wherein the rhodium concentration, palladium concentration and phosphorus concentration were quantitatively analyzed by inductively coupled plasma mass spectrometer. The recovery rates of the three were calculated by the following mathematical formula, and the units of each quantity in the formula were mol.

[0111]

[0112]

[0113]

[0114] After extraction, the recovery rate of rhodium atoms in the water phase was 97.8%, the recovery rate of palladium atoms was 98.2%, and the recovery rate of water-soluble phosphine ligand A was 96.6%.

[0115] Example 2:

[0116] The same operation was carried out except that 3.875 g (4.755 mmol) of ligand B was used instead of ligand A used in Example 1 to prepare catalyst B. It should be noted that the ratio of ligand B to rhodium atoms in the preparation of the catalyst was 15:1.

[0117] After 3 h of reaction, the conversion rate of the raw material 2,7-octadien-1-ol was 95.5%, the selectivity of the product 1,9-nonadienal was 90.4%, the selectivity of 2-methyl-1,8-octadienal was 5.3%, the normal / isomer ratio was 17:1, the selectivity of 9-hydroxy-7-nonen-1-al was 1.7%, and the selectivity of other components and high-boiling products was 2.6% in total.

[0118] The recovery rate of rhodium atoms in the aqueous phase after extraction of the hydroformylation reaction solution was 98.5%, the recovery rate of palladium atoms was 98.9%, and the recovery rate of the water-soluble phosphine ligand B was 95.8%.

[0119] Example 3:

[0120] The same operation was performed except that 10.44 g (11.095 mmol) of ligand C was used instead of ligand A used in Example 1, to prepare catalyst C. Note that the ratio of ligand C to rhodium atoms at the time of catalyst preparation was 35:1.

[0121] After 3 h of reaction, the conversion rate of the starting material 2,7-octadien-1-ol was 96.7%, the selectivity of the product 1,9-nonadienal was 89.3%, the selectivity of 2-methyl-1,8-octadienal was 7.1%, the normal / iso ratio was 12.5:1, the selectivity of 9-hydroxy-7-nonen-1-al was 2.2%, and the selectivity of other components and high-boiling products was 1.4%.

[0122] The recovery rate of rhodium atoms in the aqueous phase after extraction of the hydroformylation reaction solution was 97.1%, the recovery rate of palladium atoms was 98.3%, and the recovery rate of the water-soluble phosphine ligand C was 96.9%.

[0123] Example 4:

[0124] The same operation was performed except that 2.88 g (3.80 mmol) of ligand D was used instead of ligand A used in Example 1, to prepare catalyst D. Note that the ratio of ligand D to rhodium atoms at the time of catalyst preparation was 12:1.

[0125] After 3 h of reaction, the conversion rate of the starting material 2,7-octadien-1-ol was 96.7%, the selectivity of the product 1,9-nonadienal was 89.3%, the selectivity of 2-methyl-1,8-octadienal was 7.1%, the normal / iso ratio was 12.5:1, the selectivity of 9-hydroxy-7-nonen-1-al was 2.2%, and the selectivity of other components and high-boiling products was 1.4%.

[0126] The recovery rate of rhodium atoms in the aqueous phase after extraction of the hydroformylation reaction solution was 97.1%, the recovery rate of palladium atoms was 98.3%, and the recovery rate of the water-soluble phosphine ligand D was 96.9%.

[0127] Example 5:

[0128] The same operation was performed except that 3.13 g (3.17 mmol) of ligand E was used instead of ligand A used in Example 1, to prepare catalyst E. Note that the ratio of ligand E to rhodium atoms at the time of catalyst preparation was 10:1.

[0129] After 3 hours of reaction, the conversion of the starting material 2,7-octadien-1-ol was 96.1%, the selectivity of the product 1,9-nonadienal was 90.8%, the selectivity of 2-methyl-1,8-octadienal was 4.6%, the normal / iso ratio was 19.7:1, the selectivity of 9-hydroxy-7-nonen-1-al was 1.2%, and the selectivity of the other components and high-boiling products was 3.4%.

[0130] After extraction of the hydroformylation reaction liquid, the recovery of rhodium atoms in the aqueous phase was 99.3%, the recovery of palladium atoms was 98.6%, and the recovery of the water-soluble phosphine ligand F was 96.1%.

[0131] Example 6:

[0132] The same operation was performed except that 6.32 g (5.71 mmol) of ligand F was used instead of the ligand A used in Example 1, to prepare catalyst F. Note that the ratio of ligand F to rhodium atoms at the time of catalyst preparation was 18:1.

[0133] After 3 hours of reaction, the conversion of the starting material 2,7-octadien-1-ol was 96.1%, the selectivity of the product 1,9-nonadienal was 90.8%, the selectivity of 2-methyl-1,8-octadienal was 4.6%, the normal / iso ratio was 19.7:1, the selectivity of 9-hydroxy-7-nonen-1-al was 1.2%, and the selectivity of the other components and high-boiling products was 3.4%.

[0134] After extraction of the hydroformylation reaction liquid, the recovery of rhodium atoms in the aqueous phase was 99.3%, the recovery of palladium atoms was 98.6%, and the recovery of the water-soluble phosphine ligand F was 96.1%.

[0135] Comparative Example 1:

[0136] The same operation was performed except that 2.21 g (6.34 mmol) of ligand G was used instead of the ligand A used in Example 1, to prepare catalyst G. Note that the ratio of ligand G to rhodium atoms at the time of catalyst preparation was 20:1.

[0137] After 3 hours of reaction, the conversion of the starting material 2,7-octadien-1-ol was 92.7%, the selectivity of the product 1,9-nonadienal was 69.2%, the selectivity of 2-methyl-1,8-octadienal was 10.9%, the normal / iso ratio was 6.3:1, the selectivity of 9-hydroxy-7-nonen-1-al was 8.5%, and the selectivity of the other components and high-boiling products was 11.4%.

[0138] After extraction of the hydroformylation reaction liquid, the recovery of rhodium atoms in the aqueous phase was 65.5%, the recovery of palladium atoms was 68.2%, and the recovery of the water-soluble phosphine ligand G was 79.3%.

[0139] Comparative Example 2:

[0140] The same procedure was followed except that 2.16 g (3.80 mmol) of ligand H was used instead of ligand A used in Example 1 to prepare catalyst H. It is noted that the ratio of ligand H to rhodium atoms in the catalyst preparation was 12:1.

[0141] After 3h of reaction, the conversion of starting material 2,7-octadien-1-ol was 95.5%, the selectivity of product 1,9-nonadienal was 78.3%, the selectivity of 2-methyl-1,8-octadienal was 11.6%, the normal / iso ratio was 6.8:1, the selectivity of 9-hydroxy-7-nonen-1-al was 6.4%, and the selectivity of other components and high boiling point products was 3.7%.

[0142] After extraction of the hydroformylation reaction solution, the recovery of rhodium atoms in the aqueous phase was 79.6%, the recovery of palladium atoms was 80.1%, and the recovery of water-soluble phosphine ligand H was 84.6%.

[0143] Table 1 summarizes the results of the hydroformylation reactions and the recoveries of rhodium, palladium and phosphorus of Examples 1-6 and Comparative Examples 1-2. As can be seen from Table 1, compared to water-soluble monophosphine ligands (Comparative Examples 1 and 2), the water-soluble ligands having general formula S1 according to the present application can better achieve the one-step hydroformylation of 2,7-octadien-1-ol to directly produce dialdehyde products mainly 1,9-nonadienal, and achieve a higher normal / iso ratio than the prior art. More importantly, through the extraction process of step S2, rhodium, palladium and phosphine ligands can be recovered at a very high rate, thereby greatly reducing the cost of using catalysts.

[0144] Table 1 Results of different water-soluble phosphine ligands applied to the preparation of 1,9-nonadienal by hydroformylation of 2,7-octadien-1-ol

[0145]

[0146] Example 7:

[0147] Step S1 hydroformylation reaction:

[0148] Into a 100 mL glass flask under nitrogen atmosphere was added a solution of cyclobutanone 10 g containing Rh(OAc)2 69.3 mg (rhodium atoms 0.428 mmol) and Pd(OAc)2 14.4 mg (palladium atoms 0.064 mmol), followed by adding a solution of water 20 g containing 8.37 g (10.7 mmol) of ligand A, stirring at room temperature for 20 min to prepare catalyst A.

[0149] Into a 500 mL autoclave, 80 g of desalted water, 175 g of sulfolane, 46.7 g (0.253 mol) of 2,5-hexadiene-1-ol, and 1.17 g of triethylamine were added, and the autoclave was purged with nitrogen three times and then with a mixed gas of hydrogen and carbon monoxide (molar ratio of hydrogen to carbon monoxide: 1:1) and pressurized to 2 MPa. The autoclave was stirred at 500 rpm and heated to 80°C. Subsequently, a solution of catalyst A prepared in advance was pressurized and rapidly fed into the autoclave using a mixed gas of hydrogen and carbon monoxide (molar ratio of hydrogen to carbon monoxide: 1:1), and the total pressure was set to 2.5 MPa. The time at which the solution of catalyst A was pressurized and fed into the autoclave was defined as the start of the reaction. Note that the molar ratio of phosphine ligand A to rhodium atoms in the solution of catalyst A prepared was 25:1, the molar ratio of palladium atoms to rhodium atoms was 0.15:1, the molar ratio of rhodium atoms to the raw material 2,5-hexadiene-1-ol in the hydroformylation reaction was 0.0009:1, and the mass ratio of triethylamine to the raw material was 2.5 wt%. The water content in the aqueous solvent was 35 wt%.

[0150] The hydroformylation reaction solution after a certain period of time was subjected to quantitative analysis of the products by gas chromatography.

[0151] After 3 hours of reaction, the conversion rate of the raw material 2,5-hexadiene-1-ol was 97.6%, the selectivity of the linear product 1,9-heptandial was 87.5%, the selectivity of the branched product 2-methyl-1,6-hexandial was 10.3%, the n / i ratio was 8.5:1, the selectivity of the product in which the terminal allyl alcohol group was not isomerized to an aldehyde, i.e., 7-hydroxy-5-hepten-1-al, was 0.8%, and the selectivity of other components and high-boiling products was 1.4%.

[0152] Extraction of the reaction solution in step S2:

[0153] The autoclave was cooled to 30°C, and then the reaction mixture was pressurized and fed into a pressure-resistant glass reactor that had been pressurized to 0.3 MPa with a mixed gas of hydrogen and carbon monoxide (molar ratio: 1:1) in advance. 300 mL of cyclohexane was pumped into the glass reactor, and the temperature in the reactor was maintained at 40°C, and the mixture was stirred at 0.2 MPa for 20 min. After the stirring was stopped, the reaction mixture was separated into an oil phase and an aqueous phase, and after standing for 10 min, the extraction layer (oil phase) was drawn out from the reactor by the internal pressure. The pressure-resistant glass reactor containing the aqueous phase was maintained at 0.3 MPa and 40°C, and 300 mL of fresh cyclohexane was added again, and the mixture was stirred at the same conditions for 10 min and then allowed to stand for 5 min. The upper extraction layer was drawn out from the autoclave and combined with the cyclohexane extraction layer taken out previously, and 5 mL of water was added to the combined cyclohexane layer to perform back extraction, and the aqueous phase was introduced into the pressure-resistant glass reactor. Note that the volume ratio of cyclohexane to the hydroformylation reaction solution was 2:1.

[0154] The rhodium, palladium, and phosphine ligand contents in the aqueous phase were calculated using the rhodium, palladium, and phosphorus concentrations and the weight of the recovered aqueous phase. The rhodium, palladium, and phosphorus concentrations were quantified using inductively coupled plasma mass spectrometry (ICP-MS). After extraction, the recovery rates of rhodium atoms in the aqueous phase were 98.0%, palladium atoms 97.9%, and water-soluble phosphine ligand A 95.3%.

[0155] Example 8:

[0156] As shown in Table 2, the same operation was performed except that the following reaction conditions were substituted in Example 7: the ratio of phosphine ligand A to rhodium atoms was 10:1, the ratio of palladium atoms to rhodium atoms was 0.08:1, the mass ratio of tributylamine to raw materials was 1.3 wt%, and the water content in the sulfolane-water solvent was 58 wt%.

[0157] After 3 hours of reaction, the conversion rate of the starting material 2,6-heptadien-1-ol was 98.9%, the selectivity of the straight-chain product 1,8-octanedialdehyde was 89.4%, the selectivity of the branched 2-methyl-1,7-heptadialdehyde was 6.3%, the normal / isomer ratio was 14.2:1, the selectivity of the product 8-hydroxy-6-octen-1-al (which is not isoformed into an aldehyde at the terminal allyl alcohol group) was 2.7%, and the total selectivity of other components and high-boiling products was 1.6%.

[0158] After extraction with n-hexane, the recovery rates of rhodium atoms in the aqueous phase were 97.5%, palladium atoms 98.4%, and water-soluble phosphine ligand A 95.9%.

[0159] Example 9:

[0160] As shown in Table 2, the same operation was performed except for replacing the following reaction conditions in Example 7: the ratio of phosphine ligand E to rhodium atoms was 18:1, the ratio of palladium atoms to rhodium atoms was 0.25:1, the mass ratio of triethanolamine to raw materials was 3 wt%, and the water content in the NMP-water solvent was 55 wt%.

[0161] After 3 hours of reaction, the conversion rate of the starting material 2,7-octadien-1-ol was 97.1%, the selectivity of the straight-chain product 1,9-nonadialdehyde was 90.3%, the selectivity of the branched 2-methyl-1,8-octadialdehyde was 6.1%, the normal / isomer ratio was 14.8:1, the selectivity of the product 9-hydroxy-7-nonen-1-aldehyde (which is not isoformed from the terminal allyl alcohol group) was 1.5%, and the total selectivity of other components and high-boiling products was 2.1%.

[0162] After extraction with methylcyclohexane, the recovery rates of rhodium atoms in the aqueous phase were 98.8%, palladium atoms 97.6%, and water-soluble phosphine ligand E 97.1%.

[0163] Example 10:

[0164] The same operation was carried out except for the following reaction conditions in place of those in Example 7, i.e., the ratio of phosphine ligand E to rhodium atom was 20:1, the ratio of palladium atom to rhodium atom was 0.2:1, the starting material was 2,8-nonadien-1-ol, the mass ratio of trioctylamine to the starting material was 1.5 wt%, the water content in PEG-200-water solvent was 40 wt%.

[0165] After 3 h of the hydroformylation reaction, the conversion of the starting material 2,8-nonadien-1-ol was 99.1%, the selectivity of the straight-chain product 1,10-decanedial was 88.8%, the selectivity of the branched-chain 2-methyl-1,9-nonanedial was 7.1%, the normal / iso ratio was 12.5:1, the selectivity of the product in which the terminal allyl alcohol group was not isomerized to aldehyde, i.e., 10-hydroxy-8-decen-1-al, was 2.2%, and the selectivity of the total of other components and high-boiling products was 1.9%.

[0166] After the hydroformylation reaction solution was extracted with cyclohexane, the recovery of rhodium atom in the aqueous phase was 95.9%, the recovery of palladium atom was 96.2%, and the recovery of water-soluble phosphine ligand E was 96.5%.

[0167] Example 11:

[0168] The same operation was carried out except for the following reaction conditions in place of those in Example 7, i.e., the ratio of phosphine ligand F to rhodium atom was 15:1, the ratio of palladium atom to rhodium atom was 0.11:1, the starting material was 2,7-octadien-1-ol, the mass ratio of tripropylamine to the starting material was 2 wt%, and the water content in DMF-water solvent was 50 wt%.

[0169] After 3 h of the hydroformylation reaction, the conversion of the starting material 2,7-octadien-1-ol was 97.5%, the selectivity of the straight-chain product 1,9-nonanedial was 89.9%, the selectivity of the branched-chain 2-methyl-1,8-octanedial was 7.8%, the normal / iso ratio was 11.5:1, the selectivity of the product in which the terminal allyl alcohol group was not isomerized to aldehyde, i.e., 9-hydroxy-7-nonen-1-al, was 1.0%, and the selectivity of the total of other components and high-boiling products was 1.3%.

[0170] After the hydroformylation reaction solution was extracted with methylcyclohexane, the recovery of rhodium atom in the aqueous phase was 97.2%, the recovery of palladium atom was 96.5%, and the recovery of water-soluble phosphine ligand F was 95.6%.

[0171] Example 12:

[0172] The same operation was performed except for replacing the following reaction conditions in Example 7, i.e., the ratio of phosphine ligand F to rhodium atom was 30:1, the ratio of palladium atom to rhodium atom was 0.1:1, the mass ratio of triethylamine to raw material was 1.8 wt%, and the water content in the polyethylene glycol dimethyl ether-water solvent was 58 wt%.

[0173] After 3h of the reaction, the conversion of raw material 2,9-decadien-l-ol was 96.1%, the selectivity of linear product 1,11-undecanedial was 90.3%, the selectivity of branched 2-methyl-l,10-decanedial was 5.6%, the normal / iso ratio was 16.1:1, the selectivity of product in which the terminal allyl alcohol group was not isomerized to aldehyde, i.e., 11-hydroxy-9-decen-l- al was 2.3%, and the selectivity of other components and high boiling point products was 1.8%.

[0174] After the hydroformylation reaction solution was extracted with n-hexane, the recovery rate of rhodium atom in the water phase was 98.9%, the recovery rate of palladium atom was 98.1%, and the recovery rate of water-soluble phosphine ligand F was 96.7%.

[0175] Comparative Example 3:

[0176] The same operation was performed except for not adding triethanolamine in Example 9 as shown in Table 2.

[0177] After 3h of the reaction, the conversion of raw material 2,7-octadien-l-ol was 97.8%, the selectivity of linear product 1,9-nonanedial was 75.6%, the selectivity of branched 2-methyl-l,8-octanedial was 8.2%, the normal / iso ratio was 9.2:1, the selectivity of product in which the terminal allyl alcohol group was not isomerized to aldehyde, i.e., 9-hydroxy-7-nonen-l- al was 11.7%, and the selectivity of other components and high boiling point products was 4.5%.

[0178] After the hydroformylation reaction solution was extracted with methylcyclohexane, the recovery rate of rhodium atom in the water phase was 97.2%, the recovery rate of palladium atom was 96.6%, and the recovery rate of water-soluble phosphine ligand E was 95.3%.

[0179] Comparative Example 4:

[0180] The same operation was performed except for not adding palladium compound in Example 9 as shown in Table 2.

[0181] After 3h of reaction, the conversion of the starting material 2,7-octadien-1-ol was 96.2%, the selectivity of the linear product 1,9-nonadienal was 62.7%, the selectivity of the branched 2-methyl-1,8-octadienal was 10.3%, the n / i ratio was 6.1:1, the selectivity of the product in which the terminal allylic alcohol group was not isomerized to aldehyde, i.e. 9-hydroxy-7-nonen-1-al, was 21.9%, and the selectivity of the other components and high-boiling products was 5.1%.

[0182] After the hydroformylation reaction solution was extracted with methylcyclohexane, the recovery rate of rhodium atoms in the aqueous phase was 95.2%, and the recovery rate of the water-soluble phosphine ligand E was 93.8%.

[0183] Comparative Example 5

[0184] As shown in Table 2, the same operation was performed except that the rhodium compound was not added in place of Example 9.

[0185] After 3h of reaction, the conversion of the starting material 2,7-octadien-1-ol was 36.5%, the selectivity of the linear product 1,9-nonadienal was 34.6%, the selectivity of the branched 2-methyl-1,8-octadienal was 18.3%, the n / i ratio was 1.9:1, the selectivity of the product in which the terminal allylic alcohol group was not isomerized to aldehyde, i.e. 9-hydroxy-7-nonen-1-al, was 13.7%, and the selectivity of the other components and high-boiling products was 33.4%.

[0186] After the hydroformylation reaction solution was extracted with methylcyclohexane, the recovery rate of palladium atoms in the aqueous phase was 92.2%, and the recovery rate of the water-soluble phosphine ligand E was 90.3%.

[0187] Table 2 summarizes the results of the hydroformylation reactions and the recovery rates of rhodium, palladium and phosphorus in Examples 7 to 12 and Comparative Examples 3 to 5. As shown in Table 2, the method described in the present application has good substrate applicability, and long carbon chain dialdehyde products can be obtained in high yield from C6 to C10, and Rh, Pd and the ligand can be reused in high recovery rate after extraction. In addition, as shown in Example 9 and Comparative Examples 3 to 5, a small amount of palladium is added to the rhodium catalyst to form a Rh-Pd bimetallic complex, which can exhibit high synergistic catalysis in the catalytic hydroformylation reaction, and higher reaction selectivity and n / i ratio can be obtained. Only rhodium or palladium cannot obtain the above-mentioned beneficial synergistic effect. At the same time, in the presence of a small amount of an organic tertiary amine additive, palladium can also catalyze the further isomerization of the terminal allyl group in the starting material molecule to aldehyde, thereby obtaining long carbon chain dialdehyde products, and palladium and the organic tertiary amine additive must be added at the same time to achieve the above-mentioned beneficial effects.

[0188] Example 13

[0189] Step S1 hydroformylation reaction:

[0190] A 100 mL glass flask was charged with a solution of Rh(acac)(CO)2 135.4 mg (Rh atom 0.525 mmol) and Pd(OAc)2 11.8 mg (Pd atom 0.053 mmol) in sulfolane 10 g under nitrogen atmosphere, followed by a solution of 8.72 g (7.88 mmol) of ligand F in water 20 g, stirring at room temperature for 20 min to prepare catalyst F solution.

[0191] A 500 mL autoclave was charged with demineralized water 80 g, sulfolane 150 g, 2,7-octadien-1-ol 132.5 g (1.05 mol), triethylamine 2.65 g, purged with nitrogen for 3 times, then purged with hydrogen and carbon monoxide mixed gas (hydrogen to carbon monoxide molar ratio 2:1) and pressurized to 2 MPa, while stirring at 500 rpm and heating to 80°C. Subsequently, the previously prepared catalyst F solution was pressurized and rapidly delivered into the autoclave using hydrogen and carbon monoxide mixed gas (hydrogen to carbon monoxide molar ratio 2:1) to make the total pressure 2.5 MPa. The time when the catalyst A solution was delivered into the reactor was defined as the start of the reaction. It should be noted that the ratio of phosphine ligand A to rhodium atom in the preparation of catalyst A solution was 15:1, the ratio of palladium atom to rhodium atom was 0.1:1, the molar ratio of rhodium atom to raw material 2,7-octadien-1-ol in the hydroformylation reaction was 0.0005:1, the mass ratio of triethylamine to raw material was 2 wt%, and the water content in the aqueous solvent was 38.5 wt%. The product was quantitatively analyzed by gas chromatography for the hydroformylation reaction solution after a certain time. After 4 h of reaction, the conversion of raw material 2,7-octadien-1-ol was 98.7%, the selectivity of product 1,9-nonadienal was 90.8%, the selectivity of 2-methyl-1,8-octadienal was 5.8%, the normal / isomer ratio was 15.7:1, the selectivity of 9-hydroxy-7-nonen-1-al was 1.3%, and the selectivity of other components and high boiling point products was 2.1%.

[0192] Table 2 Preparation of different diacids by telomerization and results

[0193]

[0194]

[0195] Extraction of the reaction solution of step S2:

[0196] The autoclave was cooled to 30°C, and then the reaction mixture was pumped into a pressure-resistant glass reactor, which was previously pressurized with a mixture of hydrogen and carbon monoxide (molar ratio 2:1) to 0.3 MPa. 400 mL of cyclohexane was pumped into the glass reactor, the temperature in the reactor was maintained at 30°C, and the mixture was stirred at 0.3 MPa for 20 min. After the stirring was stopped, the reaction mixture was separated into oil and water phases, and after standing for 10 min, the extraction layer (oil phase) was pumped out through a pipe by the internal pressure. The pressure-resistant glass reactor containing the water phase was maintained at 0.3 MPa and 30°C, and 300 mL of fresh cyclohexane was added again. The mixture was stirred at the same conditions for 10 min, and then stood for 5 min. The upper extraction layer was pumped out of the autoclave and combined with the previously removed cyclohexane extraction phase, and finally 5 mL of water was added to the mixture for back extraction, and the water phase was added to the pressure-resistant glass reactor. It should be noted that the volume ratio of cyclohexane to the hydroformylation reaction liquid was 1.1:1.

[0197] The rhodium content, palladium content and phosphine ligand content contained in the water phase were calculated by the rhodium concentration, palladium concentration, phosphorus concentration and the weight of the recovered water phase, wherein the rhodium concentration, palladium concentration and phosphorus concentration were quantitatively analyzed by inductively coupled plasma mass spectrometry. After extraction, the recovery rate of rhodium atoms in the water phase was 98.9%, the recovery rate of palladium atoms was 98.4%, and the recovery rate of water-soluble phosphine ligand A was 97.6%.

[0198] Catalyst-containing water phase circulation:

[0199] The catalyst-containing raffinate water phase obtained in step S2 was recycled to the hydroformylation reaction step S1 to continue the hydroformylation reaction and extraction extraction, a total of 30 times. During this period, no catalyst and phosphine ligand were supplemented, and only 5 g of sulfolane solvent was added to each raffinate layer. Table 3 shows the changes in conversion, selectivity and catalyst recovery rate after every 5 catalyst recycling experiments.

[0200] As can be seen from Table 3, the catalyst system described in the present application has almost no significant change in conversion, selectivity of each product and recovery rate of rhodium, palladium and phosphine ligand in the water phase during the 30 reaction and extraction operations, and the catalyst can maintain high catalytic activity for a long time. At the same time, the catalyst recovery process using the extraction separation process adopted in the present application does not need to use high-temperature rectification to recover the catalyst, which also avoids the occurrence of rhodium catalyst metal precipitation and thermal degradation in the high-temperature rectification process, thereby maintaining the activity of the catalyst for a long time. Therefore, the use cost of the catalyst is greatly reduced, and the technical competitiveness is improved, which is very advantageous for the control of industrialization cost.

[0201] Step S3 rectification purification:

[0202] The 30 times of extraction oil phase are rectified by using a packed rectification column with 20 theoretical plates at normal pressure and column bottom temperature of 80-90°C, and light components including extraction agent cyclohexane, water, triethylamine, etc. are mainly taken out. The column bottom oil phase is further distilled at 0.06 KPa A and column top temperature of 61-65°C to distill out a small amount of raw material, and further distilled at column top temperature of 72-76°C to distill out most of 1,9-nonadiene, and after gas chromatography analysis, the purity is 99.5%, and in addition, there is a small amount of mixture of 1,9-nonadiene and 2-methyl-1,8-octanedial, and after gas chromatography analysis, the purity of 1,9-nonadiene is 86.2%.

[0203] Table 3 Catalyst carry-over

[0204]

[0205] Industrial applicability

[0206] According to the method of the present application, it is industrially advantageous to produce di-aldehydes. For example, 1,9-nonadiene and 2-methyl-1,8-octanedial and 1,9-nonanedioic acid are prepared by directly performing hydroformylation reaction with 2,7-octadiene-1-ol as raw material. The above di-aldehydes can be further used to produce 1,9-nonanediol and 2-methyl-1,8-octanediol, for manufacturing long carbon chain polyesters and polyurethanes, etc.; in addition, they can be converted into 1,9-nonanediamine and 2-methyl-1,8-octanediamine by reaction with ammonia and hydrogen, for producing long carbon chain high temperature nylon, etc.

[0207] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A process for the preparation of a dialdehyde, characterized by: The method comprises the following steps: S1: under the action of a catalyst, carrying out hydroformylation reaction of a non-conjugated diolefin with carbon monoxide and hydrogen in an aqueous phase to generate a reaction mixture; S2: carrying out extraction on the reaction mixture obtained in step S1, and recycling the raffinate aqueous phase containing the catalyst obtained after extraction to the hydroformylation reaction step S1; S3: carrying out at least two times of rectification on the extraction oil phase containing dialdehyde obtained in step S2 to obtain a dialdehyde product; The catalyst in step S1 is composed of a ligand and at least one Vlll transition metal compound; The Vlll transition metal element in the Vlll transition metal compound is rhodium and palladium, and the molar ratio of palladium atoms to rhodium atoms is (0.01-0.5):1; The non-conjugated diolefin is selected from one of 2,5-hexadiene-1-ol, 2,6-heptadiene-1-ol, 2,7-octadiene-1-ol, 2,8-nonadiene-1-ol and 2,9-decadiene-1-ol; An organic tertiary amine is further added in the hydroformylation reaction in step S1; The product prepared by using the above method comprises one of linear alkanedial and methyl alkanedial; The ligand is a compound of general formula (I-1) or general formula (I-2), （I-1）； （I-2）； In the formula: R 1 , R 3 is hydrogen, C1-C4alkyl, R 1 and R 3 are identical or different radicals; M + is a cation; R 11 , R 12 , R 13 , R 14 is hydrogen, substituted or unsubstituted C1-C4alkyl, the substituents being selected from the group consisting of OR f , SO3Y + ; Y + is a cation, Y + is Li + , Na + , K + or a cation HN + F 1 F 2 F 3 , any one of which, wherein F1, F2and F3are the same or different radicals, F1, F2and F3are any one of hydrogen, alkyl or cycloalkyl; R f selected from hydrogen, alkyl; R 11 , R 12 , R 13 , R 14 are identical or different radicals; R 11 , R 12 , R 13 , R 14 the substituents on the R A 1 is O, S or CR 5 R 6 any one of; R 5 , R 6 is any one of hydrogen, alkyl, R 5 , R 6 are identical or different radicals.

2. The method of claim 1, wherein: The hydroformylation reaction involved in step S1 is carried out in an aqueous phase, and the aqueous phase comprises a water-soluble solvent and water; The water-soluble solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, acetone, tetrahydrofuran, dioxane, heptanone, sulfolane, polyethylene glycol and polyethylene glycol dimethyl ether; and / or The content of water in the aqueous phase is 25-60 wt%.

3. The method of claim 1 or 2, wherein: The mass of the organic tertiary amine added is 0.1-10 wt% of the mass of the non-conjugated diolefin.

4. The method of claim 3, wherein: The organic tertiary amine is selected from one or more of trialkylamine, trialkanolamine, alicyclic tertiary amine and pyridine.

5. The method of claim 3, wherein: The reaction temperature of the hydroformylation reaction is 40-150℃, the molar ratio of the mixed gas H2 / CO of hydrogen and carbon monoxide is 0.1-10, and the reaction pressure is 0.1-10 MPa.

6. The method of claim 3, wherein: Step S2 comprises extracting the reaction mixture obtained from step S1 with a saturated aliphatic hydrocarbon or a saturated alicyclic hydrocarbon, and separating it into an extraction oil phase containing dialdehyde and a raffinate aqueous phase.

7. The method of claim 5, wherein: The saturated aliphatic hydrocarbon is selected from at least one of n-pentane, n-hexane and n-octane.

8. The method of claim 5, wherein: The saturated alicyclic hydrocarbon is selected from at least one of cyclopentane, cyclohexane, methylcyclohexane, decalin and ethers, wherein the ethers are selected from any one of dibutyl ether, diisopropyl ether, ethyl phenyl ether and methyl tert-butyl ether.

9. The method of claim 8, wherein: The extraction separation in step S2 is carried out in an inert atmosphere gas, the extraction temperature is 20-80℃, and the extraction pressure is 0.1-5 MPa.

10. The method of claim 8, wherein: The inert atmosphere gas is selected from one or more of helium, neon, argon, krypton, xenon or nitrogen.

11. The method of claim 1, wherein: The linear alkanedial is selected from one of 1,7-heptanedial, 1,8-octanedial, 1,9-nonanedial, 1,10-decanedial and 1,11-undecanedial.

12. The method of claim 1, wherein: The methyl alkanedial is selected from one of 2-methyl-1,6-hexanedial, 2-methyl- 1,7-heptanedial, 2-methyl-1,8-octanedial, 2-methyl-1,9-nonanedial, 2-methyl-1,10- decanedial. The methyl alkanedial is selected from one of 2-methyl-1,6-hexanedial, 2-methyl- 1,7-heptanedial, 2-methyl-1,8-octanedial, 2-methyl-1,9-nonanedial, 2-methyl-1,10- decanedial.

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