A hydroformylation catalyst and a process for preparing isobutyraldehyde

Abstract

The present application provides a hydroformylation catalyst and a method for preparing isobutyraldehyde. The hydroformylation catalyst comprises a metal compound and a phosphine-containing ligand containing specific sulfur. The method is: adding a substrate and a hydroformylation catalyst into a high-pressure reaction kettle, then introducing synthesis gas into the high-pressure reaction kettle, heating and reacting to prepare the corresponding formylation product. The catalyst has high regioselectivity, can reduce the n-iso isomer ratio of aldehyde in the product of olefin hydroformylation reaction, realize low n-iso ratio in the process of preparing butyraldehyde by propylene hydroformylation, and has high stability in the reaction.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis technology, specifically relating to a hydroformylation catalyst and a method for preparing isobutyraldehyde. Background Technology

[0002] Hydroformylation of olefins is a green and efficient technology for the utilization of olefins, enabling the efficient conversion and utilization of olefins. The products are oxygen-containing chemicals such as organic alcohols, acids, and esters, with high added value. Among these, the hydroformylation reaction of propylene has significant industrial importance, as it produces n-butyraldehyde and isobutyraldehyde during the reaction.

[0003] Butyraldehyde is typically further converted into n-butanol and 2-ethylhexanol, which are fundamental chemical processes used in the production of plasticizers, detergents, coatings, pharmaceuticals, and other consumer goods. Isobutyraldehyde, as a reaction byproduct, has received less attention in industrial applications. In recent years, the production capacity and demand for downstream products of isobutyraldehyde, such as neopentyl glycol and dodecyl alcohol esters, have increased, creating a supply gap and limiting supply. Therefore, significantly improving the yield of isobutyraldehyde through catalytic system innovation is crucial.

[0004] Currently, most industrial hydroformylation devices employ a second-generation low-pressure rhodium carbonyl synthesis process, producing a product N / I ratio of 6-10. For such devices, the N / I ratio of butyraldehyde can be altered by adjusting the ligand type and reaction conditions. For example, CN102741210B reports reducing the N / I ratio by adding phosphonite ligands and decreasing the transition metal concentration in the first reaction zone, while CN101657407B reports controlling and reducing the product N / I ratio by changing the concentration of organophosphite ligands relative to the transition metal during the reaction. However, these methods are difficult to operate stably over long periods, and there is still significant room for improvement in the catalytic system.

[0005] Therefore, given the existing propylene hydroformylation reaction system, it is of great significance to develop a hydroformylation catalyst that can increase the production of isobutyraldehyde. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention proposes a catalyst for hydroformylation and a method for preparing isobutyraldehyde by hydroformylation. The catalyst exhibits high regioselectivity, reducing the ortho-isomer ratio of aldehydes produced by olefin hydroformylation, achieving a low ortho-isomer ratio in the process of preparing butyraldehyde by hydroformylation of propylene, and also demonstrates high stability during the reaction.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A phosphine ligand for a hydroformylation catalyst, said phosphine ligand having the structure shown in Formula I:

[0009]

[0010] R1, R2, and R3 are each independently selected from electron-donating and / or electron-withdrawing groups, and are preferably selected from hydrogen, chlorine, methyl, methoxy, isopropoxy, and trifluoromethyl.

[0011] In one embodiment of the present invention, the phosphine ligand is any one or more of the following ligands L1-L8:

[0012]

[0013] Another object of the present invention is to provide a hydroformylation catalyst.

[0014] A hydroformylation catalyst, wherein the catalyst employs the aforementioned phosphine ligand, the hydroformylation catalyst comprising a metal compound and a phosphine-containing ligand; preferably, the molar ratio of the metal compound to the phosphine-containing ligand is 1:(1-10), more preferably 1:(2-5), wherein the molar amount of the metal compound is expressed in terms of the amount of metal atoms.

[0015] In one embodiment of the present invention, the metal compound is selected from rhodium metal compounds and / or cobalt metal compounds, preferably rhodium metal compounds, more preferably one or more of rhodium halides, rhodium-acetyl compound coordination complexes, and even more preferably one or more of rhodium chloride (RhCl3), rhodium acetylacetone dicarbonyl (Rh(CO)2acac), and rhodium acetylacetone triphenylphosphine carbonyl (ROPAC).

[0016] The molar ratio of the metal compound to the phosphine-containing ligand is 1:(1-10), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, preferably 1:(2-5), wherein the molar amount of the metal compound is expressed in terms of the amount of rhodium atoms.

[0017] The catalyst system described in this invention exhibits high catalytic activity and regioselectivity. Starting from existing hydroformylation technology, this invention designs novel catalyst compositions with multidentate phosphine ligands to adjust the selectivity of propylene hydroformylation; for example, the positive-to-isobutyraldehyde ratio can reach 0.1:0.8-1.0, significantly increasing the production capacity of isobutyraldehyde.

[0018] In the hydroformylation catalyst of the present invention, by introducing a five-membered heterocyclic compound with atoms into a multidentate phosphine ligand, the coordination strength with the metal active site can be changed due to the 6π electron system of the thiophene ring. The coordinated catalyst system has better reactivity and better stability, which can significantly improve the conversion rate and selectivity of the hydroformylation reaction, promote the formation of isomer products, and thus achieve a low positive-to-iso ratio.

[0019] In one embodiment of the present invention, the phosphine ligand has a structure as shown in Formula I;

[0020]

[0021] R1, R2, and R3 are each independently selected from electron-donating and / or electron-withdrawing groups, and are preferably selected from hydrogen, chlorine, methyl, methoxy, isopropoxy, and trifluoromethyl.

[0022] Another object of the present invention is to provide the use of a hydroformylation catalyst.

[0023] Use of a hydroformylation catalyst, wherein the catalyst employs the aforementioned phosphine ligand or is the aforementioned catalyst, the catalyst being used to catalyze the hydroformylation reaction of a reaction substrate with syngas CO / H2.

[0024] Another object of the present invention is to provide a method for hydroformylation synthesis.

[0025] A hydroformylation synthesis method, wherein the catalyst of the method is the phosphine ligand described above, or the catalyst described above, and the method comprises the following steps: adding a substrate and a hydroformylation catalyst to a high-pressure reactor, then introducing synthesis gas CO / H2 into the high-pressure reactor, heating the reactor, and preparing the corresponding formylation product.

[0026] In one embodiment of the present invention, the substrate in the synthesis method is propylene;

[0027] In one embodiment of the present invention, the product in the synthesis method is butyraldehyde;

[0028] In one embodiment of the present invention, the synthesis gas in the synthesis method comprises CO and H2.

[0029] In one embodiment of the present invention, in the synthesis method, the rhodium mass concentration in the catalyst solution is 50-400 ppm, preferably 100-200 ppm.

[0030] In one embodiment of the present invention, the molar ratio of CO to H2 in the synthesis method is (0.7-1.3):1.

[0031] In one embodiment of the present invention, the synthesis method is carried out at a reaction temperature of 60-100°C and a reaction time of 2-6 hours; the synthesis gas pressure is 1.0-3.0 MPaG.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The catalyst for propylene hydroformylation provided by this invention has high catalytic activity and stability, with a conversion rate of over 99% and a selectivity of over 90% for isoform aldehyde products. It can effectively improve regioselectivity and effectively suppress the formation of by-products, greatly changing the catalyst's control over the positive-to-iso ratio of products in the hydroformylation reaction, and making it more conducive to the formation of isomers of the hydroformylation product. Detailed Implementation

[0034] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0035] Unless otherwise specified, all raw materials used in the following specific embodiments of the present invention are obtained through commercial purchase.

[0036] Table 1 Raw Material Information

[0037]

[0038] Table 2 Equipment Information

[0039]

[0040] Gas chromatography analysis: Carrier gas: high-purity nitrogen; Injection mode: autosampler; Nitrogen flow rate: 68.1 ml / min; Vaporization chamber temperature: 270℃; Split injection, split ratio: 30:1; Injection volume: 0.2 μl; Column temperature: first-order temperature program, initial value 35℃, hold for 5 minutes, then increase to 260℃ at a rate of 15℃ / min, hold for 15 minutes; total run time: 25 minutes.

[0041] Preparation Example 1

[0042]

[0043] 2,8-Dibromodibenzothiophene (1 mol) was mixed with an ammonia solution (2.4 mol) and coupled with 10 mol% Cu2O and N-methylpyrrolidone (NMP) at 100 °C for 24 hours to obtain substance A.

[0044] Substance A was dissolved in tetrahydrofuran. The reaction system was placed in a low-temperature cold bath, and 1.3 mol of n-butyllithium solution was added dropwise to the solution. After reacting for 30 minutes, 6 mol of diphenylphosphine chloride was added, and the reaction was continued for 12 hours. The reaction was then quenched with an aqueous solution of ammonium chloride, and the mixture was separated and dried to obtain ligand L1.

[0045] Spectral characterization:

[0046] 1H NMR (500MHz, DMSO-d6) δ7.77(s,2H),7.65–7.58(m,16H),7.51(s,2H),7.44–7.36(m,8H),7.35–7.27(m,19H).

[0047] 13 C NMR (125MHz, Chloroform-d) δ142.05,139.49,137.72,131.20,129.00,127.35,126.28,123.39,123.34,115.92.

[0048] Preparation Example 2

[0049] 2,8-Dibromodibenzothiophene (1 mol) was mixed with an ammonia solution (2.4 mol) and coupled with 10 mol% Cu2O and N-methylpyrrolidone (NMP) at 100 °C for 24 hours to obtain substance A.

[0050] Substance A was dissolved in tetrahydrofuran. The reaction system was placed in a low-temperature cold bath, and 1.3 mol of n-butyllithium solution was added dropwise to the solution. After reacting for 30 minutes, 6 mol of di(p-tolyl)phosphine chloride was added, and the reaction was continued for 12 hours. The reaction was then quenched with an aqueous solution of ammonium chloride, and the mixture was separated and dried to obtain ligand L3.

[0051] Preparation Example 3

[0052] 2,8-Dibromodibenzothiophene (1 mol) was mixed with an ammonia solution (2.4 mol) and coupled with 10 mol% Cu2O and N-methylpyrrolidone (NMP) at 100 °C for 24 hours to obtain substance A.

[0053] Substance A was dissolved in tetrahydrofuran. The reaction system was placed in a low-temperature cold bath, and 1.3 mol of n-butyllithium solution was added dropwise to the solution. After reacting for 30 minutes, 6 mol of bis(4-(trifluoromethyl)phenyl)phosphine chloride was added, and the reaction was continued for 12 hours. The reaction was then quenched with an aqueous solution of ammonium chloride, and the mixture was separated and dried to obtain ligand L8.

[0054] Example 1

[0055] 0.03 g of Rh(CO)₂acac and 0.3 g of L1 phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 2.0 MPaG syngas. The reactor was heated to 80 °C and reacted for 4 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 1:1.

[0056] Example 2

[0057] 0.10 g of Rh(CO)₂acac and 0.22 g of L₃phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 2.0 MPaG syngas. The reactor was heated to 80 °C and reacted for 4 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 1:1.

[0058] Example 3

[0059] 0.06 g of Rh(CO)₂acac and 0.76 g of L8 phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 1.0 MPaG syngas. The reactor was heated to 80 °C and reacted for 4 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 1:1.

[0060] Example 4

[0061] 0.01 g of Rh(CO)₂acac and 0.10 g of L8 phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 3.0 MPaG syngas. The reactor was heated to 100 °C and reacted for 2 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 0.8:1.

[0062] Example 5

[0063] 0.19 g of Rh(CO)₂acac and 0.89 g of L8 phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 1.0 MPaG syngas. The reactor was heated to 60 °C and reacted for 6 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 1.2:1.

[0064] Example 6

[0065] 0.03 g of Rh(CO)₂acac and 1.00 g of L8 phosphine ligand were added sequentially to a high-pressure reactor. After purging with nitrogen and syngas three times, the reactor was vented. Then, 100 g of propylene was added, followed by the introduction of 2.0 MPaG syngas. The reactor was heated to 90 °C and reacted for 5 hours to obtain butyraldehyde. The syngas consisted of CO and H₂ in a molar ratio of 1:1.

[0066] Comparative Example 1

[0067] Compared to Example 1, the only difference is the use of a triphenylphosphine ligand that is not from the present application.

[0068] Comparative Example 2

[0069] Compared with Example 1, the only difference is the use of a (2,7-di-tert-butyl-9,9-dimethyl-9H-anthracene-4,5-diyl)bis(diphenylphosphine) (CAS:221462-97-1) ligand, which is not the scheme described in this application.

[0070] The reaction selectivity, conversion rate, and product positive-to-negative ratio in the above examples and comparative examples were tested, and the test results are shown in Table 3:

[0071] Table 3 Performance Test Results

[0072] Example 1 99.7 90.1 0.10 Example 2 99.5 89.8 0.12 Example 3 99.2 88.5 0.11 Example 4 99.1 89.6 0.12 Example 5 99.8 88.6 0.11 Example 6 99.4 87.3 0.10 Comparative Example 1 99.0 9.8 9.06 Comparative Example 2 98.6 17.1 4.76

[0073] In Table 1, the normal-to-iso ratio refers to the mass ratio of the normal and isomers in the hydroformylation product.

[0074] As can be seen from Table 1, the catalyst for propylene hydroformylation prepared in this invention can efficiently catalyze the synthesis of isobutyraldehyde from propylene, with a raw material conversion rate of up to 99.8%, a selectivity of up to 90% for isobutyraldehyde products, and a low ratio of positive to negative butyraldehyde.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A phosphine ligand for a hydroformylation catalyst, characterized in that, The phosphine ligand has the structure shown in Formula I: Formula I R1, R2, and R3 are each independently selected from hydrogen, chlorine, methyl, methoxy, isopropoxy, and trifluoromethyl.

2. The phosphine ligand according to claim 1, characterized in that, The phosphine ligand is any one or more of the following ligands L1-L8: 。 3. A hydroformylation catalyst, wherein the catalyst employs the phosphine ligand as described in claim 1 or 2, characterized in that, The hydroformylation catalyst comprises a metal compound and a phosphine ligand; The metal compound is a rhodium metal compound.

4. The catalyst according to claim 3, characterized in that, The molar ratio of the metal compound to the phosphine ligand is 1:(1-10), wherein the molar amount of the metal compound is expressed in terms of the amount of metal atoms.

5. The catalyst according to claim 4, characterized in that, The molar ratio of the metal compound to the phosphine ligand is 1:(2-5), wherein the molar amount of the metal compound is expressed in terms of the amount of metal atoms.

6. The catalyst according to claim 3, characterized in that, The metal compound is selected from one or more of rhodium halides and rhodium-acetyl compounds.

7. The catalyst according to claim 6, characterized in that, The metal compound is selected from one or more of rhodium chloride (RhCl3), rhodium acetylacetone dicarbonyl (Rh(CO)2acac), and rhodium acetylacetone triphenylphosphine carbonyl (ROPAC).

8. Use of a hydroformylation catalyst, wherein the catalyst employs the phosphine ligand as described in claim 1 or 2, the catalyst being used to catalyze the hydroformylation reaction of a reaction substrate with syngas CO and H2.

9. Use of a hydroformylation catalyst, wherein the catalyst is the catalyst according to any one of claims 3-7, and the catalyst is used to catalyze the hydroformylation reaction of a reaction substrate with syngas CO and H2.

10. A method for hydroformylation synthesis, wherein the catalyst of the method is the phosphine ligand as described in claim 1 or 2, the method comprising the following steps: adding a substrate and a hydroformylation catalyst to a high-pressure reactor, then introducing synthesis gases CO and H2 into the high-pressure reactor, heating the reactor to react, and preparing the corresponding formylation product.

11. A method for hydroformylation synthesis, wherein the catalyst used in the method is any one of the catalysts described in claims 3-7, and the method comprises the following steps: adding a substrate and a hydroformylation catalyst to a high-pressure reactor, then introducing synthesis gases CO and H2 into the high-pressure reactor, heating the reactor, and preparing the corresponding formylation product.

12. The synthesis method according to claim 10 or 11, characterized in that, The substrate is propylene; And / or, the product is butyraldehyde.

13. The synthesis method according to claim 10 or 11, characterized in that, In the synthesis method, the rhodium mass concentration in the catalyst solution is 50-400 ppm; And / or, in the synthesis method, the molar ratio of CO to H2 is (0.7-1.3):1; And / or, in the synthesis method, the reaction temperature is 60-100℃, the reaction time is 2-6h, and the synthesis gas pressure is 1.0-3.0MPaG.

14. The synthesis method according to claim 13, characterized in that, In the synthesis method, the rhodium mass concentration in the catalyst solution is 100-200 ppm.

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