Method for preparing glycolaldehyde by catalyzing formaldehyde hydroformylation

Abstract

The invention relates to the technical field of organic catalysis, in particular to a method for preparing glycolaldehyde by catalyzing formaldehyde hydroformylation. The method comprises the following steps: introducing CO and H2 into a mixed solution of paraformaldehyde, a rhodium compound, a ligand and a solvent, and reacting to prepare glycolaldehyde, the ligands comprise a ligand 1 and a ligand 2; the ligand 1 is selected from one or more of compounds as shown in the following L1-L8: # imgabs0 #; the structural formula of the ligand 1 is as shown in the specification, the structural formula of the ligand 2 is as shown in the specification, namely # imgabs1 # or # imgabs2 #, R1 is H, (CH2) ACH3, O-(CH2) ACH3, X or CX3, the value range of A is 0-3, and X is a halogen atom. According to the method disclosed by the invention, different ligands are subjected to dominant combination and cooperate with the rhodium-based catalyst, so that glycolaldehyde is obtained with high conversion rate and high selectivity under relatively mild conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of organic catalysis, in particular to a method for preparing glycolaldehyde by catalyzing the hydroformylation of formaldehyde. Background Art

[0002] Glycolaldehyde, the smallest sugar molecule, possesses both aldehyde and alcohol properties. It is an important organic synthesis intermediate with significant applications in the chemical, food, and pharmaceutical industries, and enjoys high market value. Formaldehyde hydroformylation is one of the most important pathways for the synthesis of ethanolaldehyde. Current research on formaldehyde hydroformylation primarily utilizes rhodium-based catalysts, a precious metal. Reducing the amount of rhodium catalyst required, improving catalyst activity under relatively mild reaction conditions, and achieving high conversion and selectivity for the preparation of ethanolaldehyde remain key challenges. The use of phosphine ligands coordinated with rhodium metal is a common strategy for the preparation of ethanolaldehyde from formaldehyde hydroformylation. For example, patent document CN118724689A discloses a method for preparing ethanolaldehyde by bridge-catalyzed formaldehyde hydroformylation. In this method, paraformaldehyde, a rhodium precursor, a second metal, a bidentate ligand, and a solvent are added to a reactor, CO and H2 are introduced in a molar ratio of 1:0.4-2.5 to displace the gas in the reactor, and the reaction is carried out at 90-120°C and a synthesis gas pressure of 7-10 MPa for 0.5-2 hours to produce ethanolaldehyde. This patent document generates a bimetallic synergistic catalyst in situ under the reaction conditions, and the monodentate bridging effect of the bidentate ligand can form a ligand-bridged bimetallic structure.

[0003] However, in the reaction of combining a rhodium source and a phosphine ligand for formaldehyde hydroformylation, some ligands have low conversion rates for the formaldehyde hydroformylation reaction but good selectivity; some ligands have high conversion rates but poor selectivity. It is of great significance to combine the advantages of different ligands, reduce the amount of rhodium used, and prepare ethanolaldehyde with high conversion rates and high selectivity. Summary of the Invention

[0004] The present invention provides a method for preparing ethanolaldehyde by catalytic hydroformylation of formaldehyde to solve the above-mentioned problems existing in existing methods. The method of the present invention combines suitable ligands with a rhodium-based catalyst to achieve high conversion and high selectivity in the preparation of ethanolaldehyde under relatively mild reaction conditions.

[0005] According to a first aspect of the present invention, the present invention provides a method for preparing glycolaldehyde by catalytic hydroformylation of formaldehyde, comprising the following steps: CO and H2 are introduced into a mixture of paraformaldehyde, a rhodium compound, a ligand and a solvent to react and prepare glycolaldehyde; Wherein, the ligand includes ligand 1 and ligand 2; the ligand 1 is selected from one or more of the compounds shown in the following L1-L8: ; The structural formula of the ligand 2 is as follows: or , R1 is H, (CH2) A CH3, O-(CH2) A CH3, X or CX3, the value of A ranges from 0 to 3, and X is a halogen atom.

[0006] Through in-depth research and innovative design, the present invention presents a method for catalyzing the hydroformylation of formaldehyde to produce glycolaldehyde by carefully selecting and combining different ligands to create a synergistic effect with a rhodium-based catalyst. In a relatively mild reaction environment, this method achieves high formaldehyde conversion rates and exhibits high selectivity for glycolaldehyde throughout the reaction process, effectively avoiding unnecessary side reactions and ensuring product purity and quality. This innovative method not only optimizes reaction conditions and reduces equipment and energy requirements, but also opens up a new path for the green and sustainable production of glycolaldehyde, possessing broad application prospects and significant industrial significance.

[0007] Furthermore, the ligand 2 is selected from one or more of the compounds shown in the following P1-P9: .

[0008] Furthermore, the molar ratio of ligand 1 to ligand 2 is (0.05-10):1. By limiting the ligand ratio range, it helps to balance the activity and selectivity of the reaction, avoiding problems such as low reaction activity or excessive side reactions caused by an inappropriate ligand ratio, and provides important parameter guidance for achieving high conversion and high selectivity in the formaldehyde hydroformylation reaction.

[0009] Furthermore, the molar ratio of the ligand 1 to the ligand 2 is (0.05-1.5): 1. This more precise ratio range helps to more accurately control the reaction process, further improve the conversion rate and selectivity of the reaction, reduce unnecessary side reactions, and lower production costs.

[0010] Furthermore, the molar ratio of the ligand to the rhodium compound is (5-100):1, preferably (10-30):1. This ratio range enables the ligand to form an effective synergistic effect with the rhodium catalyst, thereby improving the activity and stability of the catalyst and promoting the smooth progress of the formaldehyde hydroformylation reaction.

[0011] A suitable molar ratio of paraformaldehyde to rhodium compound helps improve the conversion rate and selectivity of formaldehyde hydroformylation to ethanolaldehyde, playing a significant role in enhancing the overall efficiency and economic benefits of the reaction. Furthermore, the molar ratio of paraformaldehyde to rhodium compound is (100-5000):1, preferably (500-1500):1. This ratio ensures sufficient conversion of paraformaldehyde during the reaction while avoiding problems such as incomplete reaction or excessive byproducts caused by improper raw material / rhodium compound ratios.

[0012] In some specific embodiments, the molar ratio of the paraformaldehyde to the rhodium compound is 1000:1.

[0013] Different rhodium compounds may differ in reactivity, stability, and synergistic effects with ligands. Furthermore, the rhodium compound is one of (1,5-cyclooctadiene)rhodium chloride dimer, tetracarbonyl dirhodium dichloride, dicarbonyl acetylacetonate rhodium, trichloride, or trihydrated rhodium, preferably dicarbonyl acetylacetonate rhodium (I). By providing multiple options and clarifying preferred options, the method can better adapt to different reaction conditions and process requirements, improving its versatility and flexibility and facilitating its application at different scales and under different conditions.

[0014] A suitable solvent can provide a good reaction medium, helping to improve the solubility of the reactants and the reaction rate, while also affecting the selectivity of the reaction and the stability of the product. Furthermore, the solvent is selected from one or more of N,N-dimethylacetamide, N,N-dimethylformamide, 4-methylpyridine, N-methyl-2-pyrrolidone, or N,N-dibutylformamide, preferably N,N-dimethylacetamide. By clarifying the range of solvent selection and preferred embodiments, this claim helps optimize reaction conditions, improve the overall performance and effect of the reaction, and ensure the efficient preparation of glycolaldehyde.

[0015] Appropriate reaction conditions are crucial for controlling reaction rate, product distribution, and reaction stability. Furthermore, the reaction is carried out at 3-10 MPa and 80-150°C for 1-24 hours. These conditions help ensure that the reaction proceeds under appropriate conditions, thereby improving reaction conversion and selectivity.

[0016] In order to improve the efficiency of the reaction, the reaction is further carried out under anhydrous and oxygen-free conditions.

[0017] In order to ensure the anhydrous and oxygen-free conditions of the reaction, the reaction flask containing the mixed solution of paraformaldehyde, rhodium compound, ligand and solvent was first evacuated and filled with argon three times; then, under the protection of argon, the reaction flask was placed in a reactor, and CO was introduced and discharged three times to complete the gas exchange, and then CO and H2 were added.

[0018] Furthermore, the molar ratio of CO to H₂ is (0.8-1.2):1. This limited ratio range helps ensure a balanced supply of CO and H₂ in the syngas, thereby improving the conversion rate and selectivity of the formaldehyde hydroformylation reaction. A suitable CO to H₂ ratio can avoid problems such as incomplete reaction or excessive side reactions caused by an improper gas composition ratio, making the reaction process more stable, improving the overall reaction efficiency and product quality, and is of great significance for achieving efficient and stable production of glycolaldehyde.

[0019] In some embodiments, the molar ratio of CO to H2 is 1:1.

[0020] Beneficial effects of the present invention: The present invention provides a method for catalyzing the hydroformylation of formaldehyde to produce glycolaldehyde. By combining different ligands in a synergistic manner with a rhodium-based catalyst, glycolaldehyde is produced with high conversion and selectivity under relatively mild conditions. In the formaldehyde hydroformylation reaction to produce glycolaldehyde, the amount of rhodium used can be as low as 0.1 mol% relative to the formaldehyde reactant. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] Example 1 This embodiment provides a method for preparing glycolaldehyde by catalytic hydroformylation of formaldehyde, comprising the following steps: 60 mg of paraformaldehyde, 0.1 mol% Rh(CO)2(acac), 1 mol% L2, and 1 mol% P7 were weighed, and 2 mL of N,N-dimethylacetamide was added. The reaction system was evacuated and filled with argon three times. Under argon protection, the reaction flask was sealed in a stainless steel autoclave. CO (approximately 3 MPa) was introduced into the autoclave and then purged and refilled three times to complete the gas exchange. Synthesis gas (CO:H2 molar ratio of 1:1, 5.6 MPa) was then introduced into the autoclave. The temperature was raised to 100°C and the pressure was increased to 6.8 MPa. The reaction was stirred at 400 rpm for 20 h. After completion of the reaction, the reaction was cooled to room temperature in a water bath. After completion of the reaction, the conversion and yield were determined by GC-FID using 1,4-butanediol as the internal standard.

[0023] Example 2 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 1.8 mol% L2 and 0.2 mol% P7, respectively.

[0024] Example 3 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 1.6 mol% L2 and 0.4 mol% P7, respectively.

[0025] Example 4 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 1.4 mol% L2 and 0.6 mol% P7, respectively.

[0026] Example 5 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 1.2 mol% L2 and 0.8 mol% P7, respectively.

[0027] Example 6 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 0.1 mol% L2 and 1.9 mol% P7, respectively.

[0028] Example 7 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde. The only difference from Example 1 is that the amounts of L2 and P7 used are 0.2 mol% L2 and 1.4 mol% P7, respectively.

[0029] The comparison of formaldehyde hydroformylation performance of different ligand combinations in Examples 1 to 7 is shown in Table 1 below.

[0030] Table 1

[0031] Example 8 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that P1 is used instead of P7.

[0032] Example 9 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which differs from Example 1 only in that P2 is used instead of P7.

[0033] Example 10 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that P3 is used instead of P7.

[0034] Example 11 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which differs from Example 1 only in that P4 is used instead of P7.

[0035] Example 12 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that P5 is used instead of P7.

[0036] Example 13 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which differs from Example 1 only in that P6 is used instead of P7.

[0037] Example 14 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that P8 is used instead of P7.

[0038] Example 15 This embodiment provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that P9 is used instead of P7.

[0039] The formaldehyde hydroformylation performance comparison of different ligand combinations of Examples 8 to 15 is shown in Table 2 below.

[0040] Table 2

[0041] Comparative Example 1 This comparative example provides a method for preparing ethanolaldehyde by catalyzing the hydroformylation of formaldehyde, which is different from Example 1 only in that: no P7 ligand is included, and the amount of ligand L1 used is 2 mol%.

[0042] Under this method, the conversion rate of formaldehyde is 52% and the selectivity of ethanolaldehyde is 3.6%.

[0043] As can be seen from the results of the Examples and Comparative Examples, the method of the present invention, which employs a specific ligand combination and a specific ratio, has significant advantages in the hydroformylation of formaldehyde to produce ethanolaldehyde, and can improve the formaldehyde conversion rate and ethanolaldehyde selectivity. Among them, the method of Example 7 performs best, with a formaldehyde conversion rate of 90% and a ethanolaldehyde selectivity of 95%.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing glycolaldehyde by catalyzing the hydroformylation of formaldehyde, characterized in that: The steps include: CO and H2 are introduced into a mixture of paraformaldehyde, a rhodium compound, a ligand and a solvent to react and prepare glycolaldehyde; Wherein, the ligand includes ligand 1 and ligand 2; the ligand 1 is selected from one or more of the compounds shown in the following L1-L8: ； The structural formula of the ligand 2 is as follows: or , R1 is H, (CH2) A CH3, O-(CH2) A CH3, X or CX3, the value of A ranges from 0 to 3, and X is a halogen atom.

2. The method according to claim 1, characterized in that The ligand 2 is selected from one or more of the compounds shown in the following P1-P9: 。 3. The method according to claim 1 or 2, characterized in that The molar ratio of the ligand 1 to the ligand 2 is (0.05-10):

1.

4. The method according to claim 3, characterized in that The molar ratio of the ligand 1 to the ligand 2 is (0.05-1.5):

1.

5. The method according to claim 1, wherein The molar ratio of the ligand to the rhodium compound is (5-100):1, preferably (10-30):

1.

6. The method according to claim 1, wherein The molar ratio of the paraformaldehyde to the rhodium compound is (100-5000):1, preferably (500-1500):

1.

7. The method according to claim 1, characterized in that The rhodium compound is one of (1,5-cyclooctadiene) rhodium chloride dimer, tetracarbonyl dirhodium dichloride, dicarbonyl acetylacetonate rhodium, trichloride or trihydrate rhodium, preferably dicarbonyl acetylacetonate rhodium.

8. The method according to claim 1, characterized in that The solvent is selected from one or more of N,N-dimethylacetamide, N,N-dimethylformamide, 4-methylpyridine, N-methyl-2-pyrrolidone or N,N-dibutylformamide, preferably N,N-dimethylacetamide.

9. The method according to claim 1, characterized in that The reaction is carried out at 3-10 MPa and 80-150° C. for 1-24 h.

10. The method according to claim 1, characterized in that The molar ratio of CO to H2 is (0.8-1.2):1.

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