Organic phosphine catalyst for esterification reaction and synthesis process thereof

Abstract

The invention relates to the technical field of catalyst synthesis, in particular to an organic phosphine catalyst for esterification reaction and a synthesis process thereof. The preparation method comprises the following steps: preparing a palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2 ', 6'-bis (N, N-dimethylamino)-1, 1 '-biphenyl) (2'-methylamino-1, 1 '-biphenyl-2-yl) palladium (II); preparing a catalyst admixture, namely phosphotungstic heteropoly acid; and preparing the organic phosphine catalyst. Palladium and aniline substance N-methylbiphenyl-2-amine are complexed to form a stable coordination structure palladium complex, the palladium complex reacts with methanesulfonic acid to prepare an intermediate of the palladium catalyst, and the stable coordination structure is formed by palladium and aniline, so that an active center can be effectively exposed, the efficiency and selectivity of a catalytic reaction are improved, and the catalytic activity of the catalyst is improved. And the yield of the organic phosphine catalyst is improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst synthesis, and in particular to an organic phosphine catalyst for esterification reaction and a synthesis process thereof. Background Art

[0002] In the esterification reaction, although acid or base is traditionally used as a catalyst, there are some disadvantages of using acid or base as a catalyst, such as oxidation and dehydration, which leads to a series of side reactions and reduces the yield of the esterification reaction; post-treatment is troublesome, and a large amount of acidic waste liquid is generated, which pollutes the environment. In recent years, both at home and abroad, new catalysts have been continuously explored to replace acid or base catalysts, such as organic phosphine catalysts. Organic phosphine ligands can stabilize transition metal centers through coordination and promote their catalytic activity in esterification reactions. In addition, organic phosphine catalysts can provide milder reaction conditions and higher selectivity while providing catalytic functions.

[0003] However, there are few existing methods for synthesizing organic phosphine catalysts, and the yield and purity of synthesized organic phosphine catalysts are average. Therefore, the present invention provides an organic phosphine catalyst for esterification reaction and a synthesis process thereof to make up for the gaps in the prior art. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a synthesis process of an organic phosphine catalyst for esterification reaction.

[0005] A synthesis process of an organic phosphine catalyst for an esterification reaction comprises the following steps:

[0006] S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II)

[0007] Under nitrogen protection, palladium chloride is introduced into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, and palladium chloride is slowly added dropwise, and the reaction is maintained under low temperature stirring conditions. The temperature is then raised to room temperature, stirring is continued, and insoluble matter is filtered out, and the filtrate is subjected to column chromatography to obtain a palladium complex. The palladium complex and methanesulfonic acid are dissolved in a solvent dimethylformamide, and an acid catalyst is added to react to obtain an intermediate. The intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl are added to a reaction bottle equipped with a magnetic stirring bar, and then the reaction is sealed. The reaction bottle is vacuumized, and then the reaction bottle is backfilled with argon. Then, dry tetrahydrofuran is added to the mixture. After the reaction is completed, the product in the reaction bottle is concentrated in vacuum at room temperature to remove the solvent, and pentane is continuously added until obvious solid precipitation is observed in the reaction system. The precipitated solid is separated by filtration and vacuum dried to obtain a palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II);

[0008] S2: Preparation of catalyst admixture phosphotungstic heteropoly acid

[0009] Fully dissolve Na2WO4·2H2O in deionized water, add H3PO4 under stirring, then transfer the mixed liquid to a reactor and place it in a drying oven for reaction. After the reaction is completed, take out the material from the reactor, cool it to room temperature to obtain a light yellow solution, add potassium chloride solution to the light yellow solution to obtain white crystals, dissolve the crystals in an appropriate amount of deionized water, and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid;

[0010] S3: Preparation of organic phosphine catalyst

[0011] A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, replaced with nitrogen three times, and then toluene, polyethylene glycol monomethyl ether and triethylamine are added to the three-necked reaction flask under the protection of nitrogen and an ice-water bath, and then phosphorus trichloride toluene solution is added dropwise while stirring, and finally a palladium catalyst is added to react and treat to obtain a waxy product, and phosphotungstic heteropoly acid is dissolved in deionized water, and the waxy product is added to obtain an organic phosphine catalyst.

[0012] Further, step S1 prepares the palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II), comprising the following steps:

[0013] S1.1: Under nitrogen protection, pass palladium chloride into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, then cool to 0°C and slowly add palladium chloride dropwise, the volume ratio of palladium chloride to the tetrahydrofuran solution of N-methylbiphenyl-2-amine being 1:3.4, and keep stirring at low temperature for 1-2 hours;

[0014] S1.2: The temperature is then raised to room temperature and stirring is continued for 1-2 hours. When the reaction is complete, the insoluble matter is removed by filtration and the filtrate is subjected to column chromatography to obtain a palladium complex;

[0015] S1.3: dissolving the palladium complex and methanesulfonic acid in dimethylformamide solvent in a volume ratio of 1:1, adding 2-3% of the total volume of the system acid catalyst, heating to 50-80°C for reaction for 5-6h, and then removing the solvent by rotary evaporation to obtain an intermediate;

[0016] S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stir bar, then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon;

[0017] S1.5: Then add 5-8% of the total volume of dry tetrahydrofuran to the mixture and stir at 500-600 r / min for 30 min;

[0018] S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system;

[0019] S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system. Separate the precipitated solid by filtration and vacuum dry to obtain the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl)(2'-methylamino-1,1'-biphenyl-2-yl)palladium(II).

[0020] Furthermore, step S2 prepares the catalyst admixture phosphotungstic heteropoly acid, comprising the following steps:

[0021] S2.1: Dissolve Na2WO4·2H2O in deionized water, add 26.5 parts by volume of H3PO4 under stirring, then transfer the mixed liquid to a reactor and place it in a drying oven at 393K for 12 hours;

[0022] S2.2: After the reaction is completed, the material is taken out from the reactor and cooled to room temperature to obtain a light yellow solution;

[0023] S2.3: Add 15-20 parts by volume of potassium chloride solution to the light yellow solution, stir for 10-20 minutes, filter, wash twice with 2 mol / L potassium acetate solution and methanol respectively, dry the solid at 50°C, and recrystallize twice with deionized water to obtain white crystals;

[0024] S2.4: Dissolve the crystals in an appropriate amount of deionized water and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid.

[0025] Furthermore, step S3 of preparing an organic phosphine catalyst comprises the following steps:

[0026] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution and phosphorus trichloride toluene solution are added dropwise while stirring. Finally, 2-5% of the total mass of the system is added with a palladium catalyst, and the reaction is carried out for 1 hour;

[0027] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10-11 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product;

[0028] S3.3: Dissolve phosphotungstic heteropoly acid in deionized water, add the waxy product, and the volume ratio of phosphotungstic heteropoly acid and the waxy product is 1:3. Stir the reaction at room temperature for 24 hours and then remove the water to obtain an organic phosphine catalyst.

[0029] Furthermore, the tetrahydrofuran solution of N-methylbiphenyl-2-amine in step S1.1 is obtained by mixing N-methylbiphenyl-2-amine and tetrahydrofuran in a volume ratio of 1:5.

[0030] Furthermore, the acid catalyst in step S1.3 is one of p-toluenesulfonic acid and sulfuric acid.

[0031] Furthermore, the mass ratio of the intermediate of step S1.4 to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:41.

[0032] Furthermore, the solid-to-liquid ratio of Na2WO4·2H2O and deionized water in step S2.1 is 1:1.2, and the concentration of H3PO4 is 85%.

[0033] Furthermore, the phosphorus trichloride toluene solution in step S3.1 is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:20.

[0034] An organic phosphine catalyst for esterification reaction is synthesized by the synthesis process of the organic phosphine catalyst for esterification reaction according to any one of claims 1 to 9.

[0035] Compared with the prior art, the present invention has at least the following beneficial effects:

[0036] 1. The present invention forms a palladium complex with a stable coordination structure by complexing palladium with an aniline substance N-methylbiphenyl-2-amine, and then reacts the palladium complex with methanesulfonic acid to prepare an intermediate of a palladium catalyst. The stable coordination structure formed by palladium and aniline can effectively expose the active center, thereby improving the efficiency and selectivity of the catalytic reaction. In addition, the palladium center usually forms a tetrahedral or planar square coordination geometry. N-methylbiphenyl-2-amine is used as a ligand, and methanesulfonic acid molecules can be added later to surround the palladium atom together to form a multi-coordinated complex. By adjusting the structure of the ligand, the electronic properties and spatial environment of the palladium catalyst can be regulated, and then the catalytic reaction path and product distribution can be accurately regulated, thereby accurately controlling the generation of the organic phosphine catalyst and improving the yield of the organic phosphine catalyst.

[0037] 2. The present invention prepares a palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II), and uses the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II) to prepare an organic phosphine catalyst. The palladium catalyst has excellent catalytic performance and can effectively activate a variety of organic molecules, especially for the formation of C-P, C-N and other bonds. , which is crucial in the synthesis of organic phosphine catalysts, promotes the reaction to proceed quickly and with high yield, and palladium-catalyzed reactions often have good selectivity control capabilities. The palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II) prepared by the present invention designs N-methylbiphenyl-2-amine as a ligand and controls the reaction conditions. In the process of preparing the organic phosphine catalyst, the position of the specific functional group of the product can be accurately controlled, thereby improving the performance of the organic phosphine catalyst.

[0038] 3. The present invention also prepares a catalyst admixture, phosphotungstic acid, for preparing an organic phosphine catalyst. The phosphotungstic acid has high acidity and redox properties, and can be used as an auxiliary catalyst or carrier to synergize with the organic phosphine ligand to improve the overall activity and stability of the catalytic system. In addition, the combination of the organic phosphine catalyst and the phosphotungstate can provide a unique microenvironment, which helps to control the selectivity of the reaction. For example, in asymmetric synthesis, it can guide the formation of a specific chiral center and improve the optical purity of the organic phosphine catalyst. At the same time, the good tolerance of phosphotungstate enables it to coexist with a variety of functional groups, expanding the application range of the substrate. The phosphotungstic acid can not only be used as an acid catalyst, but also participate in oxidation, reduction and other reactions, providing more possibilities for the organic phosphine catalyst in multi-step synthesis such as cross-coupling, hydrogenation, and oxidation, and realizing one-pot or multifunctional catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0040] Figure 1 The present invention is a flow chart of the synthesis process of an organic phosphine catalyst for esterification reaction used in an embodiment of the present invention.

[0041] Figure 2 This is a spectrum of the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2',6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II) prepared in an example of the present invention. DETAILED DESCRIPTION

[0042] The following is a detailed description of the synthesis process of an organic phosphine catalyst for esterification provided by the present invention in conjunction with the accompanying drawings and specific examples. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for a more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0043] Embodiment 1:

[0044] A synthesis process of an organic phosphine catalyst for esterification reaction, such as Figure 1 As shown, the following steps are included:

[0045] S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II)

[0046] S1.1: Under nitrogen protection, palladium chloride is passed into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, wherein the tetrahydrofuran solution of N-methylbiphenyl-2-amine is obtained by mixing N-methylbiphenyl-2-amine and tetrahydrofuran in a volume ratio of 1:5, then cooled to 0°C, and palladium chloride is slowly added dropwise, wherein the volume ratio of palladium chloride to the tetrahydrofuran solution of N-methylbiphenyl-2-amine is 1:3.4, and the reaction is maintained under low temperature stirring conditions for 1 hour;

[0047] S1.2: The temperature was then raised to room temperature and stirring was continued for 1 h. After the reaction was completed, the insoluble matter was removed by filtration and the filtrate was subjected to column chromatography to obtain a palladium complex;

[0048] S1.3: The palladium complex and methanesulfonic acid are dissolved in dimethylformamide solvent in a volume ratio of 1:1, and then 2% of the total volume of the system is added with sulfuric acid as an acid catalyst, heated to 80°C for 5 hours, and then the solvent is removed by rotary evaporation to obtain an intermediate, the reaction structure of which is as follows:

[0049]

[0050] S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stirring bar, wherein the mass ratio of the intermediate to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:41, and then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon;

[0051] S1.5: Then add 5% of the total volume of dry tetrahydrofuran to the mixture and stir at 600 r / min for 30 min;

[0052] S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system;

[0053] S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system. Separate the precipitated solid by filtration and vacuum dry to obtain palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II). The spectrum of palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II) is as follows: Figure 2 As shown, the reaction structure is as follows:

[0054]

[0055] S2: Preparation of catalyst admixture phosphotungstic heteropoly acid

[0056] S2.1: Na2WO4·2H2O was fully dissolved in deionized water, the solid-liquid ratio of Na2WO4·2H2O to deionized water was 1:1.2, 26.5 parts by volume of 85% H3PO4 was added under stirring, and then the mixed liquid was transferred to a reactor and placed in a drying oven at 393K for 12 hours;

[0057] S2.2: After the reaction is completed, the material is taken out from the reactor and cooled to room temperature to obtain a light yellow solution;

[0058] S2.3: Add 15 parts by volume of potassium chloride solution to the light yellow solution, stir for 10 min, filter, wash twice with 2 mol / L potassium acetate solution and methanol respectively, dry the solid at 50°C, and recrystallize twice with deionized water to obtain white crystals;

[0059] S2.4: Dissolve the crystals in an appropriate amount of deionized water and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid.

[0060] S3: Preparation of organic phosphine catalyst

[0061] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution is added dropwise while stirring. The phosphorus trichloride toluene solution is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:20. Finally, 5% of the total mass of the system is added with a palladium catalyst, and the reaction is carried out for 1 hour;

[0062] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product;

[0063] S3.3: Dissolve phosphotungstic acid in deionized water, add the waxy product, the volume ratio of phosphotungstic acid to the waxy product is 1:3, stir the reaction at room temperature for 24 hours, then remove the water to obtain an organic phosphine catalyst.

[0064] Embodiment 2:

[0065] A synthesis process of an organic phosphine catalyst for esterification reaction, such as Figure 1 As shown, the following steps are included:

[0066] S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II)

[0067] S1.1: Under nitrogen protection, palladium chloride is passed into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, wherein the tetrahydrofuran solution of N-methylbiphenyl-2-amine is obtained by mixing N-methylbiphenyl-2-amine and tetrahydrofuran in a volume ratio of 1:5, then cooled to 0°C, and palladium chloride is slowly added dropwise, wherein the volume ratio of palladium chloride to the tetrahydrofuran solution of N-methylbiphenyl-2-amine is 1:3.4, and the reaction is maintained under low temperature stirring conditions for 2 hours;

[0068] S1.2: The temperature was then raised to room temperature and stirring was continued for 2 h. After the reaction was completed, the insoluble matter was removed by filtration and the filtrate was subjected to column chromatography to obtain a palladium complex;

[0069] S1.3: The palladium complex and methanesulfonic acid are dissolved in dimethylformamide solvent in a volume ratio of 1:1, and then 2% of the total volume of the system is added with sulfuric acid as an acid catalyst, and the mixture is heated to 50°C for 6 hours, and then the solvent is removed by rotary evaporation to obtain an intermediate;

[0070] S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stirring bar, wherein the mass ratio of the intermediate to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:41, and then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon;

[0071] S1.5: Then add 5% of the total volume of dry tetrahydrofuran to the mixture and stir at 500 r / min for 30 min;

[0072] S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system;

[0073] S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system. Separate the precipitated solid by filtration and vacuum dry to obtain the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl)(2'-methylamino-1,1'-biphenyl-2-yl)palladium(II).

[0074] S2: Preparation of catalyst admixture phosphotungstic heteropoly acid

[0075] S2.1: Na2WO4·2H2O was fully dissolved in deionized water, the solid-liquid ratio of Na2WO4·2H2O to deionized water was 1:1.2, 26.5 parts by volume of 85% H3PO4 was added under stirring, and then the mixed liquid was transferred to a reactor and placed in a drying oven at 393K for 12 hours;

[0076] S2.2: After the reaction is completed, the material is taken out from the reactor and cooled to room temperature to obtain a light yellow solution;

[0077] S2.3: Add 15 parts by volume of potassium chloride solution to the light yellow solution, stir for 20 minutes, filter, wash twice with 2 mol / L potassium acetate solution and methanol respectively, dry the solid at 50°C, and recrystallize twice with deionized water to obtain white crystals;

[0078] S2.4: Dissolve the crystals in an appropriate amount of deionized water and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid.

[0079] S3: Preparation of organic phosphine catalyst

[0080] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution is added dropwise while stirring. The phosphorus trichloride toluene solution is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:20. Finally, 5% of the total mass of the system is added with a palladium catalyst, and the reaction is carried out for 1 hour;

[0081] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 11 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product;

[0082] S3.3: Dissolve phosphotungstic heteropoly acid in deionized water, add the waxy product, and the volume ratio of phosphotungstic heteropoly acid and the waxy product is 1:3. Stir the reaction at room temperature for 24 hours and then remove the water to obtain an organic phosphine catalyst.

[0083] Embodiment 3:

[0084] A synthesis process of an organic phosphine catalyst for esterification reaction, such as Figure 1 As shown, the following steps are included:

[0085] S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II)

[0086] S1.1: Under nitrogen protection, palladium chloride is passed into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, wherein the tetrahydrofuran solution of N-methylbiphenyl-2-amine is obtained by mixing N-methylbiphenyl-2-amine and tetrahydrofuran in a volume ratio of 1:5, then cooled to 0°C, and palladium chloride is slowly added dropwise, wherein the volume ratio of palladium chloride to the tetrahydrofuran solution of N-methylbiphenyl-2-amine is 1:3.4, and the reaction is maintained under low temperature stirring conditions for 1 hour;

[0087] S1.2: The temperature was then raised to room temperature and stirring was continued for 1 h. After the reaction was completed, the insoluble matter was removed by filtration and the filtrate was subjected to column chromatography to obtain a palladium complex;

[0088] S1.3: dissolving the palladium complex and methanesulfonic acid in a solvent dimethylformamide at a volume ratio of 1:1, adding 3% of the total volume of the system as an acid catalyst sulfuric acid, heating to 80°C for 5 hours, and then removing the solvent by rotary evaporation to obtain an intermediate;

[0089] S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stirring bar, wherein the mass ratio of the intermediate to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:41, and then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon;

[0090] S1.5: Then add 8% of the total volume of dry tetrahydrofuran to the mixture and stir at 600 r / min for 30 min;

[0091] S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system;

[0092] S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system. Separate the precipitated solid by filtration and vacuum dry to obtain the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl)(2'-methylamino-1,1'-biphenyl-2-yl)palladium(II).

[0093] S2: Preparation of catalyst admixture phosphotungstic heteropoly acid

[0094] S2.1: Na2WO4·2H2O was fully dissolved in deionized water, the solid-liquid ratio of Na2WO4·2H2O to deionized water was 1:1.2, 26.5 parts by volume of 85% H3PO4 was added under stirring, and then the mixed liquid was transferred to a reactor and placed in a drying oven at 393K for 12 hours;

[0095] S2.2: After the reaction is completed, the material is taken out from the reactor and cooled to room temperature to obtain a light yellow solution;

[0096] S2.3: Add 20 parts by volume of potassium chloride solution to the light yellow solution, stir for 10 minutes, filter, wash twice with 2 mol / L potassium acetate solution and methanol respectively, dry the solid at 50°C, and recrystallize twice with deionized water to obtain white crystals;

[0097] S2.4: Dissolve the crystals in an appropriate amount of deionized water and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid.

[0098] S3: Preparation of organic phosphine catalyst

[0099] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution is added dropwise while stirring. The phosphorus trichloride toluene solution is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:20. Finally, 2% of the total mass of the system is added as a palladium catalyst, and the reaction is carried out for 1 hour;

[0100] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product;

[0101] S3.3: Dissolve phosphotungstic heteropoly acid in deionized water, add the waxy product, and the volume ratio of phosphotungstic heteropoly acid and the waxy product is 1:3. Stir the reaction at room temperature for 24 hours and then remove the water to obtain an organic phosphine catalyst.

[0102] Comparative Example 1:

[0103] Compared with Example 1, the difference of Comparative Example 1 is that, in step S1, a palladium complex is not prepared, but palladium chloride and methanesulfonic acid are directly reacted, specifically: "S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl)(2'-methylamino-1,1'-biphenyl-2-yl) palladium (II)

[0104] S1.3: dissolve palladium chloride and methanesulfonic acid in dimethylformamide solvent in a volume ratio of 1:1, add 2% of the total volume of the system as an acid catalyst sulfuric acid, heat to 80°C for 5 hours, and then remove the solvent by rotary evaporation to obtain an intermediate;

[0105] S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stirring bar, wherein the mass ratio of the intermediate to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:41, and then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon;

[0106] S1.5: Then add 5% of the total volume of dry tetrahydrofuran to the mixture and stir at 600 r / min for 30 min;

[0107] S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system;

[0108] S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system, separate the precipitated solid by filtration, and vacuum dry to obtain a palladium catalyst, and calculate the yield and purity of the organophosphine catalyst.

[0109] Comparative Example 2:

[0110] Compared with Example 1, the difference of Comparative Example 2 is that step S5 is not performed to prepare the catalyst blend phosphotungstic heteropoly acid, and the organic phosphine catalyst is directly prepared in step S3, specifically: "S3: Preparation of organic phosphine catalyst

[0111] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution is added dropwise while stirring. The phosphorus trichloride toluene solution is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:20. Finally, 5% of the total mass of the system is added with a palladium catalyst, and the reaction is carried out for 1 hour;

[0112] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10 hours, stop stirring, turn off the nitrogen, and place in a sealed condition overnight. The next day, filter under nitrogen protection, vacuum remove the solvent in the filtrate to obtain a waxy product, and dry it to obtain an organic phosphine catalyst. The yield and purity of the organic phosphine catalyst were calculated.

[0113] Comparative Example 3:

[0114] Compared with Example 1, the difference of Comparative Example 3 is that no palladium catalyst is used to prepare the organic phosphine catalyst in step S3, specifically: "S3: modified xanthan gum graft copolymerization

[0115] S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution is added dropwise while stirring. The phosphorus trichloride toluene solution is prepared by dissolving phosphorus trichloride in toluene. The volume ratio of phosphorus trichloride to toluene is 1.6:20. The reaction is carried out for 1 hour.

[0116] S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product;

[0117] S3.3: Dissolve tungstophosphoric acid in deionized water, add the waxy product, the volume ratio of tungstophosphoric acid to the waxy product is 1:3, stir the reaction at room temperature for 24 hours, remove the water, and obtain an organic phosphine catalyst. Statistic the yield and purity of the organic phosphine catalyst.

[0118] The yield and purity of the organophosphine catalysts of Examples 1-3 and Comparative Examples 1-3 were recorded.

[0119] Table 1:

[0120]

[0121] It can be seen from the table that the yields of Examples 1-3 are 88.21%, 87.06% and 87.59% respectively, and the purity is 98%. The yield of Comparative Example 1 is only 68.33%, and the purity is 87%, the yield of Comparative Example 2 is 56.15%, and the purity is 78%, and the yield of Comparative Example 3 is 85.49%, and the purity is 83%. It can be seen that the palladium and the aniline substance N-methylbiphenyl-2-amine complex to form a stable coordination structure palladium complex improves the yield and purity of the organic phosphine catalyst, and the palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis (N, N-dimethylamino) -1, 1'-biphenyl) (2'-methylamino-1, 1'-biphenyl-2-yl) palladium (II) improves the purity of the organic phosphine catalyst.

[0122] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A synthesis process of an organic phosphine catalyst for esterification reaction, characterized in that: The steps include: S1: Preparation of palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II) Under nitrogen protection, palladium chloride is introduced into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, and palladium chloride is slowly added dropwise, and the reaction is maintained under low temperature stirring conditions. The temperature is then raised to room temperature, stirring is continued, and insoluble matter is filtered out, and the filtrate is subjected to column chromatography to obtain a palladium complex. The palladium complex and methanesulfonic acid are dissolved in a solvent dimethylformamide, and an acid catalyst is added to react to obtain an intermediate. The intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl are added to a reaction bottle equipped with a magnetic stirring bar, and then the reaction is sealed. The reaction bottle is vacuumized, and then the reaction bottle is backfilled with argon. Then, dry tetrahydrofuran is added to the mixture. After the reaction is completed, the product in the reaction bottle is concentrated in vacuum at room temperature to remove the solvent, and pentane is continuously added until obvious solid precipitation is observed in the reaction system. The precipitated solid is separated by filtration and vacuum dried to obtain a palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II); S2: Preparation of catalyst admixture phosphotungstic heteropoly acid Fully dissolve Na2WO4·2H2O in deionized water, add H3PO4 under stirring, then transfer the mixed liquid to a reactor and place it in a drying oven for reaction. After the reaction is completed, take out the material from the reactor, cool it to room temperature to obtain a light yellow solution, add potassium chloride solution to the light yellow solution to obtain white crystals, dissolve the crystals in an appropriate amount of deionized water, and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid; S3: Preparation of organic phosphine catalyst A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, replaced with nitrogen three times, and then toluene, polyethylene glycol monomethyl ether and triethylamine are added to the three-necked reaction flask under the protection of nitrogen and an ice-water bath, and then phosphorus trichloride toluene solution is added dropwise while stirring, and finally a palladium catalyst is added to react and treat to obtain a waxy product, and phosphotungstic heteropoly acid is dissolved in deionized water, and the waxy product is added to obtain an organic phosphine catalyst.

2. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 1, characterized in that: Step S1: preparing a palladium catalyst methanesulfonic acid (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II), comprising the following steps: S1.1: Under nitrogen protection, pass palladium chloride into a tetrahydrofuran solution of N-methylbiphenyl-2-amine, then cool to 0°C and slowly add palladium chloride dropwise, the volume ratio of palladium chloride to the tetrahydrofuran solution of N-methylbiphenyl-2-amine being 1:3.4, and keep stirring at low temperature for 1-2 hours; S1.2: The temperature is then raised to room temperature and stirring is continued for 1-2 hours. When the reaction is complete, the insoluble matter is removed by filtration and the filtrate is subjected to column chromatography to obtain a palladium complex; S1.3: dissolving the palladium complex and methanesulfonic acid in dimethylformamide solvent in a volume ratio of 1:1, adding 2-3% of the total volume of the system acid catalyst, heating to 50-80°C for reaction for 5-6h, and then removing the solvent by rotary evaporation to obtain an intermediate; S1.4: Add the intermediate and 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl to a reaction bottle equipped with a magnetic stir bar, then seal the reaction bottle, evacuate the reaction bottle, and then backfill the reaction bottle with argon; S1.5: Then add 5-8% of the total volume of dry tetrahydrofuran to the mixture and stir at 500-600 r / min for 30 min; S1.6: Monitor the progress of the reaction by nuclear magnetic resonance. After the reaction is completed, concentrate the product in the reaction flask in a vacuum at room temperature to remove the solvent until 10% of the original volume of liquid remains in the reaction system; S1.7: Continue to add pentane until obvious solid precipitation is observed in the reaction system. Separate the precipitated solid by filtration and vacuum dry to obtain the palladium catalyst methanesulfonate (2-dicyclohexylphosphine-2', 6'-bis(N,N-dimethylamino)-1,1'-biphenyl)(2'-methylamino-1,1'-biphenyl-2-yl)palladium(II).

3. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 2, characterized in that: Step S2 is to prepare the catalyst admixture phosphotungstic heteropoly acid, comprising the following steps: S2.1: Dissolve Na2WO4·2H2O in deionized water, add 26.5 parts by volume of H3PO4 under stirring, then transfer the mixed liquid to a reactor and place it in a drying oven at 393K for 12 hours; S2.2: After the reaction is completed, the material is taken out from the reactor and cooled to room temperature to obtain a light yellow solution; S2.3: Add 15-20 parts by volume of potassium chloride solution to the light yellow solution, stir for 10-20 minutes, filter, wash twice with 2 mol / L potassium acetate solution and methanol respectively, dry the solid at 50°C, and recrystallize twice with deionized water to obtain white crystals; S2.4: Dissolve the crystals in an appropriate amount of deionized water and pass through a strong acid ion exchange resin column for chromatography to obtain phosphotungstic heteropoly acid.

4. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 3, characterized in that: Step S3 prepares an organic phosphine catalyst, comprising the following steps: S3.1: A constant pressure dropping funnel and a nitrogen protection device are installed on a three-necked reaction flask, the reaction system is evacuated, and replaced with nitrogen three times. Then, under the protection of nitrogen and an ice-water bath, 100 parts by volume of toluene, 35.8 parts by volume of polyethylene glycol monomethyl ether and 38.3 parts by volume of triethylamine are added to the three-necked reaction flask, and then 11.6 parts by volume of phosphorus trichloride toluene solution and phosphorus trichloride toluene solution are added dropwise while stirring. Finally, 2-5% of the total mass of the system is added with a palladium catalyst, and the reaction is carried out for 1 hour; S3.2: After the reaction, remove the ice-water bath, naturally warm to room temperature, continue stirring for 10-11 hours, stop stirring, turn off the nitrogen, and leave overnight in a sealed condition. The next day, filter under nitrogen protection, and vacuum remove the solvent in the filtrate to obtain a waxy product; S3.3: Dissolve phosphotungstic heteropoly acid in deionized water, add the waxy product, and the volume ratio of phosphotungstic heteropoly acid and the waxy product is 1:

3. Stir the reaction at room temperature for 24 hours and then remove the water to obtain an organic phosphine catalyst.

5. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 4, characterized in that: The tetrahydrofuran solution of N-methylbiphenyl-2-amine in step S1.1 is obtained by mixing N-methylbiphenyl-2-amine and tetrahydrofuran in a volume ratio of 1:

5.

6. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 5, characterized in that: The acid catalyst in step S1.3 is one of p-toluenesulfonic acid and sulfuric acid.

7. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 6, characterized in that: The mass ratio of the intermediate of step S1.4 to 2-dicyclohexylphosphine-2',6'-bis(dimethylamino)-1,1'-biphenyl is 37:

41.

8. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 7, characterized in that: The solid-to-liquid ratio of Na2WO4·2H2O and deionized water in step S2.1 is 1:1.2, and the concentration of H3PO4 is 85%.

9. The synthesis process of an organic phosphine catalyst for esterification reaction according to claim 8, characterized in that: The phosphorus trichloride toluene solution in step S3.1 is prepared by dissolving phosphorus trichloride in toluene, and the volume ratio of phosphorus trichloride to toluene is 1.6:

20.

10. An organic phosphine catalyst for esterification reaction, synthesized by the synthesis process of the organic phosphine catalyst for esterification reaction according to any one of claims 1 to 9.

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