A process for the production of beta-butyrolactone by asymmetric hydrogenation of a diketene

Abstract

The application provides a method for preparing beta-butyrolactone through asymmetric hydrogenation of diacetylene ketone, which is prepared through catalyzing asymmetric hydrogenation of diacetylene ketone under a hydrogen atmosphere by using a metal active component and a pyridine ring phosphine ligand as a catalyst. The method uses a hydroxyl-containing nitrogen heterocyclic phosphine ligand as a ligand, and a metal such as palladium, rhodium or ruthenium as an active metal, so that the conversion rate and selectivity of the reaction are improved, the stability of the catalyst is good, and the catalyst can be used multiple times. The synthesis route of the catalyst used in the method is short, the yield is high, the number of times of reusing is large, and the method has a good cost advantage.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a method for preparing β-butyrolactone by asymmetric hydrogenation of diketene as a raw material. Background Technology

[0002] β-Butyrolactone, also known as β-methylpropiolactone, is an important chemical intermediate that can be used in the production of biodegradable materials and other fields.

[0003] Currently, β-butyrolactone is mainly derived from artificial synthesis.

[0004] US Patent No. 2,763,664 discloses a method for preparing β-butyrolactone by hydrogenation of diketene as a raw material, using palladium black as a catalyst and ethyl acetate as a solvent, with a reaction temperature of 0°C; the yield of β-butyrolactone after the reaction is 93%.

[0005] Patent EP0955303A2 discloses a type of ruthenium-based organophosphorus ligand catalyst with high catalytic activity, which yields β-butyrolactone with an optical purity of over 92%.

[0006] Patent CN113025664 A discloses a method for preparing β-butyrolactone, in which diketene is hydrogenated in the presence of a rhodium or iridium catalyst to obtain β-butyrolactone with a yield of 93%.

[0007] The above methods all involve large amounts of precious metals, resulting in high costs. Furthermore, the raw material diethyl ketone is prone to polymerization side reactions, leading to numerous byproducts and reduced reaction yield.

[0008] In summary, existing methods for the artificial synthesis of β-butyrolactone suffer from drawbacks such as long catalyst preparation processes, high costs, and low reaction yields, and are prone to deactivation during catalysis. Therefore, there is a need to develop an efficient synthesis process that shortens the catalyst preparation process, increases the number of catalyst reuses, and reduces catalyst costs during production. Summary of the Invention

[0009] To address the aforementioned problems in the existing technology, this invention provides a method for the asymmetric hydrogenation of diketene to prepare β-butyrolactone. This method uses diketene as a starting material and performs one-step catalytic hydrogenation to obtain β-butyrolactone, offering advantages such as low catalyst cost and high reaction yield.

[0010] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0011] A method for preparing β-butyrolactone by asymmetric hydrogenation of diketene is disclosed, which uses a metal active component and a phosphine ligand containing a pyridine ring as catalysts to catalyze the asymmetric hydrogenation reaction of diketene under a hydrogen atmosphere to prepare β-butyrolactone.

[0012] The reaction formula is as follows:

[0013]

[0014] In this invention, the active metal component is selected from one or more of palladium, rhodium, or ruthenium, preferably one or more of palladium and rhodium.

[0015] In this invention, the metal active ingredient is selected from one or more of metal halides, metal oxides, or metal acetates, preferably one or more of the oxides, halides, or acetates corresponding to palladium, rhodium, and ruthenium;

[0016] In this invention, the structural formula of the phosphine ligand containing the pyridine ring is:

[0017]

[0018] Among them, the substituents R1-R3 are selected from halogen, hydrogen, and C, respectively. 1-6 Alkyl, C 6-14 One or more of aryl groups, preferably one or more of hydrogen, methyl, ethyl, phenyl, and halogen.

[0019] In this invention, the molar ratio of the metal active component to the phosphine ligand containing the pyridine ring is 1:1 to 1:3;

[0020] Preferably, the metal active component and ligand can be synthesized in situ, and the metal active component and ligand are mixed evenly and then fed into the reaction system together.

[0021] In this invention, the method for preparing the phosphine ligand containing the pyridine ring is as follows:

[0022] Under a nitrogen atmosphere, a mixture of pyridine and 4-methylsulfonylphenol was reacted at 0–20 °C for 0.5–1 h in the presence of a solvent. Then, phosphorus trichloride was added, and the reaction was carried out at 5–15 °C for 0.5–1.5 h. The solvent was then removed by filtration to obtain the ligand.

[0023] The solvent is one or more selected from dichloromethane, tetrahydrofuran, and diethyl ether;

[0024] The structural formula of the pyridine compound is as follows:

[0025]

[0026] Wherein, the substituents R1-R3 are defined in the same way as those for pyridine-containing phosphine ligands, and are preferably selected from one or more of 2,6-dibromopyridine, 4-methyl-2,6-dibromopyridine, 4-ethyl-2,6-dibromopyridine, 4-aryl-2,6-dibromopyridine, and 2,4,6-tribromopyridine;

[0027] The mass ratio of the solvent to the total mass of other raw materials is 50:1-10:1; the molar ratio of the pyridine compound, 4-methylsulfonylphenol, and phosphorus trichloride is 1:4:1-1:6:2.

[0028] In this invention, the solvent for the hydrogenation reaction is one or more of methanol, ethanol, acetone, and tetrahydrofuran, preferably one or more of methanol, acetone, and tetrahydrofuran; the mass ratio of the solvent for the hydrogenation reaction to diethyl ketone is 4:1-10:1, preferably 5:1-8:1.

[0029] In this invention, the total mass of the metal active component and ligand accounts for 0.05%-1% of the total mass of the reaction solution, preferably 0.1%-0.5%.

[0030] In this invention, the hydrogenation reaction temperature is 30-100℃, preferably 40-90℃; the pressure is 0.1-2MPa(G), preferably 0.2-1.0MPa(G); and the reaction time is 0.5-4h, preferably 1-3h.

[0031] In this invention, the hydrogenation reaction is carried out in an intermittent manner. First, the solvent and diketene are added to the reaction vessel and mixed evenly. Then, the active metal component and the pyridine ring ligand are mixed and added to the reaction vessel. After the gas in the vessel is replaced with nitrogen, hydrogen is fed in.

[0032] After the hydrogenation reaction is complete, it is required to cool rapidly to room temperature, preferably to below 30°C within 5 minutes. The mixture containing diketene and solvent is then filtered, and the catalyst remains in the reactor for reuse.

[0033] The advantages of the catalyst in this invention are:

[0034] The catalyst has a short synthesis route, high yield, can be reused multiple times, and has low production cost. The pyridine ring in the ligand is a flexible ring, which can adjust the catalyst configuration through chemical bond rotation under high temperature conditions to maintain high catalytic activity. The sulfone group in the ligand has strong polarity, which can promote the combination of the catalyst and reactants, enhance its influence on catalyst activity, reduce reaction temperature, and thus increase the yield of β-butyrolactone.

[0035] The method of this invention achieves a conversion rate of over 97% in the asymmetric hydrogenation reaction of diketene, and a selectivity of up to 98.5% for β-butyrolactone. The catalyst can be reused more than 60 times. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below. These embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in existing literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0037] The main raw material information is as follows:

[0038] Table 1 Chemical Information in Examples

[0039]

[0040]

[0041] The gas chromatography test conditions of this invention are as follows:

[0042] Instrument model: Agilent GC2030; Column: HP-5 (30m×0.25mm×0.25μm); Column temperature: initial temperature 40℃, increased to 120℃ at 5℃ / min, then increased to 250℃ at 15℃ / min, held for 6min; Injector temperature: 250℃; FID detector temperature: 250℃; Split injection, split ratio 60:1; Injection volume: 2.0μL; H2 flow rate: 40mL / min; Air flow rate: 360mL / min.

[0043] Instrument model: Agilent GC2030; Column: CHIRALDEX G-TA 180℃: 30m x 250μm x 0.12μm; Column temperature: initial 80℃, then 2℃ / min to 130℃ for 1 minute, then 10℃ / min to 170℃ for 10 minutes, run time 40 minutes. Injector temperature: 80℃; FID detector temperature: 200℃; Split injection, split ratio 100:1; Injection volume: 2.0μL; H2 flow rate: 40mL / min; Air flow rate: 400mL / min.

[0044] Example 1:

[0045] Synthetic ligands:

[0046] The synthesis of the ligands was carried out under nitrogen protection in a glove box.

[0047] 200 g of dichloromethane solvent was added to a three-necked flask, followed by 1.000 g of 2,6-dibromopyridine and 2.981 g of 4-methylsulfonylphenol. The mixture was reacted at 0 °C for 0.5 h. Then, 0.580 g of phosphorus trichloride was added, and the mixture was reacted at 15 °C for 1.5 h. After filtration, the solvent was dried under vacuum at 40 °C and 1 kPa(A) for 4 h to obtain the ligand.

[0048] The NMR structure confirmation data of the ligand in Example 1 are shown below:

[0049] 1 H NMR (CDCl3, 400MHz, TMS): δ8.74(t,1H), 7.58(d,4H), 7.71(d,4H), 7.48(d,4H), 7.23(d,4H), 3.29(s,6H), 3.41(s,6H)

[0050] Hydrogenation reaction:

[0051] The hydrogenation reaction was carried out in a batch reactor with an effective volume of 500 ml and a self-priming agitator. During the hydrogenation experiment, 250 g of acetone, 50 g of diketene, 0.12 g of the prepared ligand, and 0.1 g of palladium dibromide were added to the reactor. The reactor was set to a rotation speed of 300 rpm. The inlet and outlet valves of the carrier gas in the reaction tube were opened, and nitrogen carrier gas was introduced at a flow rate of 1 L / min. After purging with nitrogen for 30 min, hydrogen gas was introduced to pressurize to 1 MPa(G). The reactor heating jacket was then turned on, and the reactor temperature was raised to 60 °C. After 1.5 h, the reaction was stopped, and the reaction solution was cooled to below 30 °C within 5 min. A sample of the reaction solution was then taken for GC chromatography analysis.

[0052] The catalyst was filtered out and reused repeatedly, then reacted again under the same conditions. Samples were taken and the reaction results were analyzed by GC chromatography. The asymmetric hydrogenation of diketene achieved a conversion rate of 98.9% and a β-butyrolactone selectivity of 98.5%. When the catalyst was reused 60 times, the hydrogenation conversion rate reached a maximum of 97.6%, and the β-butyrolactone selectivity reached 98.2%.

[0053] Example 2:

[0054] Synthetic ligands:

[0055] The synthesis of the ligands was carried out under nitrogen protection in a glove box.

[0056] 200 g of tetrahydrofuran solvent was added to a three-necked flask, followed by 1.000 g of 2,4,6-tribromopyridine and 4.1 g of 4-methylsulfonylphenol. The mixture was reacted at 20 °C for 0.5 h. Then, 0.850 g of phosphorus trichloride was added, and the mixture was reacted at 5 °C for 1.5 h. After filtration, the solvent was dried under vacuum at 40 °C and 1 kPa(A) for 4 h to obtain the ligand.

[0057] The NMR structure confirmation data of the ligand in Example 2 are shown below:

[0058] 1H NMR (CDCl3, 400MHz, TMS): 7.57(d,4H), 7.72(d,4H), 7.48(d,4H), 7.23(d,4H), 6.80(s,2H), 3.29(s,6H), 3.41(s,6H)

[0059] Hydrogenation reaction:

[0060] The hydrogenation reaction was carried out in a batch reactor with an effective volume of 500 ml and a self-priming agitator. During the hydrogenation experiment, 100 g of methanol, 15 g of diketene, 0.12 g of the prepared ligand, and 0.05 g of palladium dibromide were added to the reactor. The reactor was set to a rotation speed of 300 rpm. The inlet and outlet valves of the carrier gas in the reaction tube were opened, and nitrogen carrier gas was introduced at a flow rate of 1 L / min. After purging with nitrogen for 30 min, hydrogen gas was introduced to pressurize to 0.5 MPa(G). The reactor heating jacket was then turned on, and the reactor temperature was raised to 30 °C. After 3 h, the reaction was stopped, and the reaction solution was cooled to below 30 °C within 5 min. A sample of the reaction solution was then taken for GC chromatography analysis.

[0061] The catalyst was filtered out and reused repeatedly, then reacted again under the same conditions. Samples were taken and analyzed by GC chromatography. The results showed that the asymmetric hydrogenation conversion of diketene reached 99.1%, and the selectivity for β-butyrolactone reached 98.3%. When the catalyst was reused 60 times, the hydrogenation conversion reached a maximum of 98.7%, and the selectivity for β-butyrolactone reached 97.4%.

[0062] Example 3:

[0063] Synthetic ligands:

[0064] The synthesis of the ligands was carried out under nitrogen protection in a glove box.

[0065] 150 g of dichloromethane solvent was added to a three-necked flask, followed by 0.95 g of 4-methyl-2,6-dibromopyridine and 3.2 g of 4-methylsulfonylphenol. The mixture was reacted at 10 °C for 1 h. Then, 0.83 g of phosphorus trichloride was added, and the mixture was reacted at 10 °C for 1 h. After filtration, the solvent was dried under vacuum at 40 °C and 1 kPa(A) for 4 h to obtain the ligand.

[0066] The NMR structure confirmation data of the ligand in Example 3 are shown below:

[0067] 1 H NMR (CDCl3, 400MHz, TMS): 7.57(d,4H), 7.72(d,4H), 7.48(d,4H), 7.23(d,4H), 6.35(s,2H), 3.27(s,6H), 3.40(s,6H), 2.34(s,3H)

[0068] Hydrogenation reaction:

[0069] The hydrogenation reaction was carried out in a batch reactor with an effective volume of 500 ml and a self-priming agitator. During the hydrogenation experiment, 200 g of acetone, 20 g of diketene, 0.5 g of the prepared ligand, and 0.48 g of rhodium dibromide were added to the reactor. The reactor was set to a rotation speed of 300 rpm. The inlet and outlet valves of the carrier gas in the reaction tube were opened, and nitrogen carrier gas was introduced at a flow rate of 1 L / min. After purging with nitrogen for 30 min, hydrogen gas was introduced to pressurize the reactor to 0.1 MPa(G). The reactor heating jacket was then turned on, and the reactor temperature was raised to 100 °C. After 2 h, the reaction was stopped, and the reaction solution was cooled to below 30 °C within 5 min. A sample of the reaction solution was then taken for GC chromatography analysis.

[0070] The catalyst was filtered out and reused repeatedly, then reacted again under the same conditions. Samples were taken and the reaction results were analyzed by GC chromatography. The asymmetric hydrogenation of diketene achieved a conversion rate of 99.5% and a β-butyrolactone selectivity of 98.1%. When the catalyst was reused 60 times, the hydrogenation conversion rate reached a maximum of 98.9%, and the β-butyrolactone selectivity reached 97.6%.

[0071] Example 4:

[0072] Synthetic ligands:

[0073] The synthesis of the ligands was carried out under nitrogen protection in a glove box.

[0074] 150 g of diethyl ether was added to a three-necked flask, followed by 1.6 g of 4-aryl-2,6-dibromopyridine and 4.1 g of 4-methylsulfonylphenol. The mixture was reacted at 5 °C for 1 h. Then, 1.2 g of phosphorus trichloride was added, and the mixture was reacted at 15 °C for 0.5 h. After filtration, the solvent was dried under vacuum at 40 °C and 1 kPa(A) for 4 h to obtain the ligand.

[0075] The NMR structure confirmation data of the ligand in Example 4 are shown below:

[0076] 1 H NMR (CDCl3, 400MHz, TMS): 7.57(d,4H), 7.72(d,4H), 7.48-7.52(m,8H), 7.41(m,1H), 7.23(d,4H), 6.67(s,2H), 3.27(s,6H), 3.40(s,6H)

[0077] Hydrogenation reaction:

[0078] The hydrogenation reaction was carried out in a batch reactor with an effective volume of 500 ml and a self-priming agitator. During the hydrogenation experiment, 160 g of tetrahydrofuran solvent, 20 g of diketene, 0.3 g of the prepared ligand, and 0.25 g of palladium dibromide were added to the reactor. The reactor was set to a rotation speed of 300 rpm. The inlet and outlet valves of the carrier gas in the reaction tube were opened, and nitrogen carrier gas was introduced at a flow rate of 1 L / min. After purging with nitrogen for 30 min, hydrogen gas was introduced to pressurize to 0.6 MPa(G). The reactor heating jacket was then turned on, and the reactor temperature was raised to 60 °C. After 1.5 h, the reaction was stopped, and the reaction solution was cooled to below 30 °C within 5 min. A sample of the reaction solution was then taken for GC chromatography analysis.

[0079] The catalyst was filtered out and reused repeatedly, then reacted again under the same conditions. Samples were taken and analyzed by GC chromatography. The results showed that the asymmetric hydrogenation conversion of diketene reached 98.1%, and the selectivity for β-butyrolactone reached 97.7%. When the catalyst was reused 60 times, the hydrogenation conversion reached a maximum of 97.4%, and the selectivity for β-butyrolactone reached 96.9%.

[0080] Comparative Example 1:

[0081] Hydrogenation reaction:

[0082] The hydrogenation reaction was carried out in a batch reactor with an effective volume of 500 ml and a self-priming agitator. During the hydrogenation experiment, 160 g of tetrahydrofuran, 20 g of diketene, and 0.35 g of palladium dibromide were added to the reactor. The reactor was set to a rotation speed of 300 rpm. The inlet and outlet valves of the carrier gas in the reaction tube were opened, and nitrogen carrier gas was introduced at a flow rate of 1 L / min. After purging with nitrogen for 30 min, hydrogen gas was introduced to pressurize the reactor to 0.6 MPa(G). The reactor heating jacket was then turned on, and the reactor temperature was raised to 70 °C. After 1.5 h, the reaction was stopped, and the reaction solution was cooled to below 30 °C within 5 min. A sample of the reaction solution was then taken for GC chromatography analysis.

[0083] The catalyst was filtered out and reused, then reacted again under the same conditions. Samples were taken and analyzed by GC chromatography. The results showed that the asymmetric hydrogenation of diketene achieved a conversion rate of 94.3% and a selectivity of 92.7% for β-butyrolactone.

Claims

1. A method for the asymmetric hydrogenation of diketene to prepare β-butyrolactone, characterized in that, Using a metal active component and a phosphine ligand containing a pyridine ring as catalysts, β-butyrolactone was prepared by catalyzing the asymmetric hydrogenation of diketene under a hydrogen atmosphere. The active metal component is selected from one or more of palladium and rhodium; the active metal component is selected from one or more of metal halides or metal acetates. The structural formula of the phosphine ligand containing the pyridine ring is: In this context, substituents R1 and R3 are selected from halogens, and R2 is one of hydrogen, methyl, ethyl, phenyl, or halogen.

2. The method according to claim 1, characterized in that, The molar ratio of the metal active component to the phosphine ligand containing the pyridine ring is 1:1 to 1:

3.

3. The method according to claim 1, characterized in that, The preparation method of phosphine ligands containing pyridine rings is as follows: Under a nitrogen atmosphere, a mixture of pyridine compound and 4-methylsulfonylphenol was reacted at 0–20 °C for 0.5–1 h in the presence of a solvent. Then, phosphorus trichloride was added, and the reaction was carried out at 5–15 °C for 0.5–1.5 h. The ligand was obtained by filtration and drying of the solvent.

4. The method according to claim 3, characterized in that, The solvent is one or more of dichloromethane, tetrahydrofuran, and diethyl ether.

5. The method according to claim 3, characterized in that, The structural formula of the pyridine compound is: The definitions of substituents R1-R3 are the same as those for pyridine-containing phosphine ligands.

6. The method according to claim 3, characterized in that, The mass ratio of the solvent to the total mass of other raw materials is 50:1-10:

1.

7. The method according to claim 3, characterized in that, The molar ratio of the pyridine compound, 4-methylsulfonylphenol, and phosphorus trichloride is 1:4:1 to 1:6:

2.

8. The method according to claim 1, characterized in that, The solvent for the hydrogenation reaction is one or more of methanol, ethanol, acetone, and tetrahydrofuran.

9. The method according to claim 1, characterized in that, The mass ratio of the solvent to diethyl ketone in the hydrogenation reaction is 4:1 to 10:

1.

10. The method according to claim 9, characterized in that, The mass ratio of the solvent to diethyl ketone in the hydrogenation reaction is 5:1 to 8:

1.

11. The method according to claim 1, characterized in that, The total mass of the active metal component and ligands accounts for 0.05%-1% of the total mass of the reaction solution.

12. The method according to claim 11, characterized in that, The total mass of the active metal component and ligands accounts for 0.1%-0.5% of the total mass of the reaction solution.

13. The method according to claim 1, characterized in that, The hydrogenation reaction temperature is 30-100℃, the pressure is 0.1-2MPa(G), and the reaction time is 0.5-4h.

14. The method according to claim 13, characterized in that, The hydrogenation reaction temperature is 40-90℃; the pressure is 0.2-1.0MPa(G); and the reaction time is 1-3h.

15. The method according to claim 1, characterized in that, The hydrogenation reaction is carried out in a batch manner. First, the solvent and diketene are added to the reactor and mixed evenly. Then, the active metal component and the pyridine ring ligand are mixed and added to the reactor. After the gas in the reactor is replaced with nitrogen, hydrogen is fed in.

16. The method according to claim 1, characterized in that, After the hydrogenation reaction is complete, it is required to cool rapidly to room temperature, filter to obtain a mixture containing diketene and solvent, and leave the catalyst in the reactor for reuse.

17. The method according to claim 16, characterized in that, After the hydrogenation reaction is complete, the mixture is cooled to below 30°C within 5 minutes and filtered to obtain a mixture containing diketene and solvent. The catalyst is left in the reactor for reuse.

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