A diphosphine polymer supported palladium catalytic material, a preparation method and application thereof

Abstract

This invention discloses a bisphosphine polymer-supported palladium catalytic material, its preparation method, and its application. The material comprises a bisphosphine polymer support and a palladium source supported on the bisphosphine polymer support. The palladium source chelates and coordinates with a bidentate phosphine ligand on the bisphosphine polymer support, and the palladium is dispersed in an atomically single-site manner. The bisphosphine polymer support is obtained by free radical polymerization of an olefin-functionalized bidentate phosphine monomer and an olefin-functionalized comonomer. In the bisphosphine polymer-supported palladium catalytic material of this invention, the bisphosphine ligand and the active palladium metal can form a spatially favorable coordination configuration and a relatively stable active structure. Furthermore, the palladium metal acts as a catalyst in a single-site manner, which improves the catalytic activity and regioselectivity of the reaction, avoids palladium loss, and improves the reusability of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of palladium catalysis technology, specifically relating to a bisphosphine polymer-supported palladium catalytic material, its preparation method, and its application. Background Technology

[0002] The hydrogen esterification of olefins refers to the reaction of an olefin with carbon monoxide and an alcohol in the presence of a metal catalyst to yield an ester with one more carbon atom than the olefin. Among the many methods for synthesizing organic carboxylic acid esters, this is the most atom-economical and convenient method. The following scheme shows the general reaction equation for the hydrogen esterification of olefins:

[0003] Synthesized organic carboxylic acid esters are an important class of oxygen-containing compounds, widely used in fine chemicals, pharmaceuticals, pesticides, food additives, fragrances, coatings, and paints. For example, methyl propionate is widely used in the food, feed, and cosmetic industries as a solvent, additive, preservative, or fragrance. Furthermore, it is an important chemical intermediate, a key raw material for the production of polymethyl methacrylate (PMMA). Therefore, developing efficient catalytic materials for the hydrogen esterification of olefins is of great significance.

[0004] Porous organic polymers are a class of porous network materials composed of organic structural units linked by covalent bonds. They possess characteristics such as designable structure, easy functionalization, high specific surface area, excellent stability, and tunable pore size. By designing the structure of the polymer monomers, the distribution of functional groups and pore structure of the polymer can be specifically controlled, providing a feasible technical route for preparing highly active and selective heterogeneous catalysts. This technology has been widely studied and applied in the field of heterogeneous catalysis (Chem. Soc. Rev., 2012, 41, 2083–2094).

[0005] According to relevant literature, bisphosphine ligands play a crucial role in controlling the catalytic activity and selectivity of homogeneous catalytic systems for olefin hydrogen esterification reactions (Chem. Commun., 1999, 1877-1878; Angew. Chem. Int. Ed., 2017, 56, 5267-5271; WO 96 / 19434; WO 2004 / 014552 Al; US 2017 / 0022234 Al; CN111087306A). In particular, bisphosphine ligands with specific spatial bite angles can form advantageous configurations with tunable coordination numbers and stable active species with palladium, which is beneficial for obtaining excellent reaction activity and regioselectivity (Coord. Chem. Rev., 2018, 355, 150–172). However, the recycling of noble palladium and bisphosphine ligands remains a significant and unavoidable challenge. Furthermore, the olefin hydrogen esterification reaction involving heterogeneous catalytic systems still suffers from low activity, poor regioselectivity, and severe loss of active metals, resulting in high production costs (Catal. Sci. Technol., 2014, 4, 1092-1103; Mol. Catal., 2020, 498, 111239).

[0006] Therefore, there is an urgent need to develop a new type of highly efficient bisphosphine polymer catalytic material that can improve the activity and regioselectivity of olefin hydrogen esterification reactions, while also enabling the effective recovery and reuse of the noble metal palladium and bisphosphine ligands.

[0007] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a bisphosphine polymer-supported palladium catalytic material, its preparation method, and its application. This invention solves the problems of poor reactivity and regioselectivity in heterogeneous hydrogen esterification reactions, as well as severe loss of active metals and ligands. It can significantly improve the activity and regioselectivity of olefin hydrogen esterification reactions, and the catalyst has excellent reusability.

[0009] To achieve the above objectives, the present invention provides a bisphosphine polymer-supported palladium catalytic material, comprising: a bisphosphine polymer support, and a palladium source supported on the bisphosphine polymer support, wherein the palladium source chelates and coordinates with bidentate phosphine ligands on the bisphosphine polymer support, and the palladium is dispersed in the form of atomically single sites; the bisphosphine polymer support is obtained by a free radical polymerization reaction of olefin-functionalized bidentate phosphine monomers and olefin-functionalized comonomers.

[0010] The chemical structural formula of the olefin-functionalized bidentate phosphine monomer is shown in Formula I: In Formula I, X is selected from N; n is selected from integers from 1 to 5; R 1 It is selected from phenyl, 2-pyridyl or tert-butyl.

[0011] The chemical structural formula of the olefin-functionalized comonomer is shown in Formula II, with the vinyl substitution sites being para, meta, or ortho: .

[0012] This invention employs a novel bidentate phosphine monomer as shown in Formula I. The oxygen atom in the parent nucleus precisely fixes the spatial angle of the bisphosphine group, allowing it to coordinate with the palladium center to form a dominant coordination configuration with an adjustable coordination number and a stable active species. The palladium metal exerts its catalytic effect at a single site, and combined with the pore confinement effect of the polymer framework, the two work synergistically to effectively improve the regioselectivity and catalytic stability of the hydrogen esterification reaction. The catalytic properties of the palladium-supported bisphosphine polymer catalyst of this invention improve its catalytic activity and regioselectivity in the hydrogen esterification reaction, while avoiding palladium loss and improving the catalyst's reusability.

[0013] Preferably, the chemical structural formula of the olefin-functionalized bidentate phosphine monomer is selected from any one of the following: .

[0014] Preferably, the chemical structural formula of the olefin-functionalized comonomer is selected from any one of the following: .

[0015] Preferably, the palladium source is selected from at least one of palladium chloride, palladium acetylacetone, palladium acetate, palladium di(acetonitrile) chloride, palladium triphenylphosphine chloride, palladium trifluoroacetate, palladium nitrate, tri(dibenzylindeneacetone)dipalladium, or 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene)palladium dichloride.

[0016] Preferably, the molar ratio of the olefin-functionalized bidentate phosphine monomer to the olefin-functionalized comonomer is (0.05~1):1. More preferably, the molar ratio of the olefin-functionalized bidentate phosphine monomer to the olefin-functionalized comonomer is (0.05~0.50):1.

[0017] Preferably, the mass ratio of the bisphosphine polymer support to the palladium source is (20~50):1.

[0018] A second objective of this invention is to provide a method for preparing the aforementioned bisphosphine polymer-supported palladium catalytic material, the method comprising: In an inert atmosphere, olefin-functionalized bidentate phosphine monomers as shown in Formula I, olefin-functionalized comonomers as shown in Formula II, free radical initiators, and a first organic solvent are mixed and subjected to free radical polymerization at 80~120℃ to obtain a bisphosphine polymer carrier. In an inert atmosphere, the bisphosphine polymer support and palladium metal are reacted in a second organic solvent at 20-60°C to obtain a bisphosphine polymer-supported palladium catalyst.

[0019] Preferably, the first organic solvent and the second organic solvent are independently selected from at least one of ethanol, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, n-hexane, toluene, anisole, dichloromethane, and chloroform.

[0020] Preferably, the free radical initiator is selected from azobisisobutyronitrile, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, or methyl ethyl ketone peroxide. These substances are all free radical initiators, and under heating conditions, they will generate free radicals to activate olefins, form alkyl free radicals, and further undergo polymerization reactions.

[0021] Preferably, the free radical polymerization reaction takes 1 to 72 hours.

[0022] Preferably, the coordination reaction takes 1 to 24 hours.

[0023] A third objective of this invention is to provide the application of the aforementioned bisphosphine polymer-supported palladium catalyst in olefin hydrogen esterification reactions.

[0024] Preferably, the bisphosphine polymer-supported palladium catalyst is used to catalyze the olefin hydrogen esterification reaction of olefins, organic alcohols and CO; wherein the olefin is selected from terminal olefins or terminal aryl olefins with a chain length of C1 to C8; and the organic alcohol is selected from saturated alcohols or aryl alcohols with a chain length of C1 to C5.

[0025] More preferably, the bisphosphine polymer-supported palladium catalyst, p-toluenesulfonic acid, and organic alcohol are placed in a high-pressure reactor, air is purged, and olefins and CO are introduced, and the reaction is stirred under heating conditions at 100°C.

[0026] The bisphosphine polymer-supported palladium catalytic material, its preparation method, and its application of the present invention solve the problems of poor reactivity and regioselectivity, as well as severe loss of active metals and ligands in heterogeneous hydrogen esterification reactions, and have the following advantages: The bisphosphine polymer-supported palladium catalyst of this invention exhibits excellent catalytic activity, regioselectivity, and stability in the hydrogen esterification reaction of olefins, achieving efficient synthesis of organic carboxylic acid esters from olefin carbonylation. In this bisphosphine polymer-supported palladium catalyst, the bisphosphine ligand and the active palladium metal form a spatially favorable coordination configuration and a relatively stable active structure, with the palladium metal acting as a single catalytic site. This improves the catalytic activity and regioselectivity of the reaction, avoids palladium metal loss, and enhances the reusability of the catalyst. Data from the examples show that the catalyst of this invention exhibits excellent activity in the hydrogen esterification reaction of olefins (with a maximum TOF of 351 h). -1 It possesses high regioselectivity (up to 99% selectivity for straight-chain products) and catalyst stability (the catalyst can be reused at least 10 times), enabling efficient catalysis of olefin carbonylation to synthesize organic carboxylic acid esters. Attached Figure Description

[0027] Figure 1 The olefin-functionalized bidentate phosphine monomer L1 in Example 1 1 H NMR spectrum.

[0028] Figure 2 NMR of the olefin-functionalized bidentate phosphine monomer L1 in Example 1 13 C10 NMR spectrum.

[0029] Figure 3 NMR of the olefin-functionalized bidentate phosphine monomer in Example 1 31 P NMR spectrum.

[0030] Figure 4 This is a schematic diagram of the structure of catalyst A in Example 1.

[0031] Figure 5 The image shows the FT-IR characterization of catalyst A in Example 1.

[0032] Figure 6 This is the BET adsorption-desorption curve of catalyst A in Example 1.

[0033] Figure 7 The thermogravimetric (TGA) characterization diagram of catalyst A in Example 1 is shown.

[0034] Figure 8 This is a scanning electron microscope (SEM) image of catalyst A in Example 1.

[0035] Figure 9 This is a high-resolution transmission electron microscope (HR-TEM) image of catalyst A in Example 1.

[0036] Figure 10 This is an aberration-corrected high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of catalyst A in Example 1. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that: Unless otherwise specified in the examples, conditions should be followed according to standard conditions or the manufacturer's recommendations. Instruments whose manufacturers are not specified are all commercially available products. Raw materials and reagents whose manufacturers are not specified are all commercially available goods or can be prepared using known methods.

[0039] In this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are used only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0040] The features mentioned in this invention can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification, provided that there is no contradiction in the combination of these features. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0041] In the description of this invention, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] This invention provides a method for preparing a bisphosphine polymer-supported palladium catalytic material, comprising the following steps: (1) Under an inert atmosphere, olefin-functionalized bidentate phosphine monomer, olefin-functionalized comonomer, free radical initiator and first organic solvent are mixed to undergo free radical polymerization reaction to obtain bisphosphine polymer carrier; (2) Under an inert atmosphere, the bisphosphine polymer support, the palladium source, and the second organic solvent are mixed to allow the bisphosphine polymer support to chelate and coordinate with palladium, thereby obtaining a bisphosphine polymer-supported palladium catalyst.

[0043] The olefin-functionalized bidentate phosphine monomer used in this invention is prepared by a lithiation-phosphineation reaction of a dibromo derivative S and a disubstituted phosphine chloride M. The general synthetic route is as follows: Formula S represents a dibromodimethylamine, where X is N and n is an integer from 1 to 5; Formula M represents a disubstituted phosphine chloride, where the substituent R... 1 It is phenyl, 2-pyridyl or tert-butyl.

[0044] The olefin-functionalized comonomer used in this invention is prepared by lithiation of bromostyrene with phosphorus trichloride. The general synthetic route is as follows: Formula S' represents p-bromostyrene, m-bromostyrene, or o-bromostyrene.

[0045] The following examples illustrate in detail the preparation method of the bisphosphine polymer-supported palladium catalyst provided by the present invention.

[0046] Example 1 (1) Preparation of olefin-functionalized bidentate phosphine monomer (L1) In an argon atmosphere and at a low temperature of -78 °C, a hexane solution of n-butyllithium (2.5 M, 8.4 mL, 21 mmol) was added dropwise to an anhydrous tetrahydrofuran solution of S1 (5.16 g, 10 mmol) (60 mL) over a period of 10 min, and the mixture was stirred for 1 h under these conditions. Then, a tetrahydrofuran solution of diphenylphosphine chloride (4.84 g, 22 mmol, dissolved in 5 mL of tetrahydrofuran) was added dropwise to the reaction system over a period of 5 min. The reaction mixture was stirred at -78 °C. ℃ After stirring for another hour, the system was slowly brought back to room temperature and stirred overnight at room temperature.

[0047] After the reaction was completed, the reaction was quenched with 2 mol / L HCl aqueous solution, and then the reaction mixture was extracted with 50 mL EA (ethyl acetate) and 50 mL H2O. The organic phases were combined, dried with anhydrous Na2SO4, filtered, and concentrated under vacuum to remove the solvent. Petroleum ether and ethyl acetate were used as eluents (volume ratio of 100:1). The crude product was purified by rapid column chromatography to obtain 3.6 g of a pale yellow viscous liquid, which was the olefin-functionalized bidentate phosphine monomer L1, with a yield of 50%.

[0048] The above-mentioned olefin-functionalized bidentate phosphine monomer L1 1 H NMR, 13 C NMR, 31 The P NMR spectra are shown in [reference 1]. Figure 1 , Figure 2 and Figure 3 The structural characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.35 – 7.09 (m, 20H), 6.54 (ddd, J = 11.8,8.9, 3.8 Hz, 4H), 6.07 (dd, J = 4.9, 3.0 Hz, 2H), 5.70 – 5.44 (m, 4H), 4.96(ddd, J = 18.6, 13.7, 1.4 Hz, 8H), 3.62 (d, J = 5.1 Hz, 8H).

[0049] 13 C NMR (101 MHz, CDCl3) δ 151.69, 151.51, 144.63, 137.41, 137.29,134.14, 133.94, 128.53, 128.37, 128.30, 128.21, 128.19, 128.15, 128.12,118.75, 118.17, 116.22, 114.56, 53.48.

[0050] 31 P NMR (162 MHz, CDCl3) δ -15.09.

[0051] HRMS (ESI + ): m / z Found 751.2990, calculated 751.2983 for [M+Na] + .

[0052] (2) Preparation of olefin functionalized comonomer (L4) Under an argon atmosphere and at a low temperature of -78 °C, a hexane solution of n-butyllithium (2.5 M, 12.6 mL, 31.5 mmol) was added dropwise to an anhydrous tetrahydrofuran solution of p-bromostyrene (S2, 6.04 g, 33 mmol) over approximately 20 min. The mixture was stirred for 1 h under these conditions, and then a tetrahydrofuran solution of phosphorus trichloride (1.37 g, 10 mmol, dissolved in 5 mL of tetrahydrofuran) was added dropwise to the reaction system over approximately 5 min. The reaction mixture was stirred at -78 °C for 1 h, then slowly brought to room temperature and stirred overnight at room temperature.

[0053] After the reaction was complete, the reaction was quenched with a 2 mol / L HCl aqueous solution, and then the reaction mixture was extracted with 50 mL EA and 50 mL H2O. The combined organic phases were dried over anhydrous Na2SO4, filtered, and the solvent was removed by vacuum concentration. Using petroleum ether:ethyl acetate at a volume ratio of 100:1 as the eluent, the crude product was purified by rapid column chromatography to give 2.4 g of a white solid product, which was the olefin-functionalized comonomer L4, in 70% yield.

[0054] The structural characterization data of the aforementioned olefin-functionalized comonomer L4 are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.36 (d, J = 7.0 Hz, 6H), 7.27 (t, J = 7.7 Hz, 6H), 6.69 (dd, J = 17.6, 10.9 Hz, 3H), 5.76 (d, J = 17.6 Hz, 3H), 5.26 (d, J = 10.9Hz, 3H).

[0055] 13 C NMR (101 MHz, CDCl3) δ 138.09, 136.81, 136.70, 136.47, 134.09, 133.90, 126.47, 126.40, 114.82.

[0056] 31 P NMR (162 MHz, CDCl3) δ -6.85.

[0057] (3) Preparation of bisphosphine polymer support Under an argon atmosphere, L1 (120 mg, 0.165 mmol), L4 (480 mg, 1.41 mmol), and the free radical initiator azobisisobutyronitrile (16.4 mg, 0.1 mmol) were dissolved in 6 mL of tetrahydrofuran. The resulting reaction solution was transferred to a hydrothermal reactor, stirred at room temperature for 0.5 h, and then heated to 100 °C in a forced-air drying oven and allowed to stand for 24 h.

[0058] After the free radical polymerization reaction was completed, the resulting white solid was filtered, washed with tetrahydrofuran (20 mL × 3), and dried under vacuum at 60 °C for 12 h to obtain the bisphosphine polymer support.

[0059] (4) Preparation of bisphosphine polymer-supported palladium catalyst Under an argon atmosphere, Pd(acac)2 (12.2 mg, 0.04 mmol) was dissolved in 10 mL of tetrahydrofuran, and then 400 mg of the bisphosphine polymer carrier was added. The mixture was stirred at room temperature for 12 h.

[0060] After the bisphosphine ligand and palladium coordination reaction was completed, the resulting pale yellow solid was filtered, washed with tetrahydrofuran (20 mL × 3), and dried under vacuum at 60 °C for 12 h to obtain a bisphosphine polymer-supported palladium catalyst, denoted as catalyst A.

[0061] See the schematic diagram of the structure of catalyst A prepared above. Figure 4 The structure and morphology of the obtained catalyst A were characterized, and the results are as follows:

[0062] Fourier transform infrared (FT-IR) spectra are shown below. Figure 5 Characteristic absorption peaks of the polymer backbone and phosphine ligands can be observed; nitrogen adsorption-desorption test results are shown in […]. Figure 6 This confirms that the material has a typical porous structure; the thermogravimetric analysis (TGA) results are shown in [reference needed]. Figure 7 This indicates that the material exhibits no significant weight loss below 200 °C, demonstrating excellent thermal stability. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) characterizations are shown in the figures below. Figure 8 , Figure 9 The material is visible as randomly aggregated nanoparticles; the aberration-corrected high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of catalyst A is shown below. Figure 10 The palladium species are distributed in a monodisperse state at the atomic level on the support, without obvious nanoparticle aggregation, which provides direct evidence that palladium plays a catalytic role in a single-site form.

[0063] Example 2 (1) Preparation of olefin-functionalized bidentate phosphine monomer (L2) The preparation of the olefin-functionalized bidentate phosphine monomer L1 in Example 1 is basically the same, except that: The tetrahydrofuran solution of M1 (4.84 g, 22 mmol, dissolved in 5 mL tetrahydrofuran) was used instead of the tetrahydrofuran solution of diphenylphosphine chloride M0 (4.84 g, 22 mmol, dissolved in 5 mL tetrahydrofuran).

[0064] Post-treatment column chromatography purification, using petroleum ether and ethyl acetate as eluents (volume ratio 20:1), yielded 2.4 g of a colorless viscous liquid, namely the olefin-functionalized bidentate phosphine monomer L2, with a yield of 33%.

[0065] (2) Preparation of olefin functionalized comonomer (L4) in the same manner as in Example 1 (3) Preparation of bisphosphine polymer support The preparation of the bisphosphine polymer support is basically the same as that in Example 1, except that: The 120 mg olefin-functionalized bidentate phosphine monomer L1 in Example 1 was replaced with 120 mg olefin-functionalized bidentate phosphine monomer L2.

[0066] (4) Preparation of the bisphosphine polymer-supported palladium catalyst material as in Example 1 The only difference from Example 1 is: The resulting bisphosphine polymer-supported palladium catalyst, which is named catalyst B, is derived from the use of different bisphosphine polymer supports.

[0067] Example 3 (1) Preparation of olefin-functionalized bidentate phosphine monomer (L3) The preparation of the olefin-functionalized bidentate phosphine monomer L1 in Example 1 is basically the same, except that: The tetrahydrofuran solution of M2 (4.84 g, 22 mmol, dissolved in 5 mL tetrahydrofuran) was used instead of the tetrahydrofuran solution of diphenylphosphine chloride M0 (4.84 g, 22 mmol, dissolved in 5 mL tetrahydrofuran).

[0068] Post-processing yielded 2.14 g of a colorless viscous liquid, namely the olefin-functionalized bidentate phosphine monomer L3, with a yield of 33%.

[0069] (2) Preparation of olefin functionalized comonomer (L4) in the same manner as in Example 1 (3) Preparation of bisphosphine polymer support The preparation of the bisphosphine polymer support is basically the same as that in Example 1, except that: The 120 mg olefin-functionalized bidentate phosphine monomer L1 in Example 1 was replaced with 106 mg (0.146 mmol) of olefin-functionalized bidentate phosphine monomer L3.

[0070] (4) Preparation of the bisphosphine polymer-supported palladium catalyst material as in Example 1 The only difference from Example 1 is: The resulting bisphosphine polymer-supported palladium catalyst, which is denoted as catalyst C, is derived from the different bisphosphine polymer supports used.

[0071] Example 4 It is basically the same as Example 1, except that: In the preparation of the bisphosphine polymer support, 240 mg (0.330 mmol) of olefin-functionalized bidentate phosphine monomer L1 was weighed to replace 120 mg of olefin-functionalized bidentate phosphine monomer L1. The resulting bisphosphine polymer-supported palladium catalyst is denoted as catalyst D.

[0072] Example 5 It is basically the same as Example 1, except that: In the preparation of the bisphosphine polymer support, 480 mg (0.660 mmol) of olefin-functionalized bidentate phosphine monomer L1 was weighed to replace 120 mg of olefin-functionalized bidentate phosphine monomer L1. The resulting bisphosphine polymer-supported palladium catalyst is denoted as catalyst E.

[0073] Example 6 (1) Preparation of olefin-functionalized bidentate phosphine monomer L1 as in Example 1 (2) Preparation of olefin functionalized comonomer (L5) The preparation of the olefin-functionalized comonomer is basically the same as that in Example 1, except that: The anhydrous tetrahydrofuran (40 mL) of m-bromostyrene (S3, 6.04 g, 33 mmol) was replaced with anhydrous tetrahydrofuran (40 mL) of p-bromostyrene (S2, 6.04 g, 33 mmol) to give 2.4 g of white solid product, which is the olefin functionalized comonomer L5, with a yield of 70%.

[0074] The structural characterization data of the aforementioned olefin-functionalized comonomer L5 are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.39 (d, J = 8.1 Hz, 6H), 7.34 – 7.24 (m, 3H), 7.17 (t, J = 7.2 Hz, 3H), 6.64 (dd,J = 17.6, 10.9 Hz, 3H), 5.67 (d, J = 17.6 Hz, 3H), 5.21 (d, J = 11.0 Hz, 3H).

[0075] 13 C NMR (101 MHz, CDCl3) δ 137.80 (d, J = 7.7 Hz), 137.33 (d, J = 11.1Hz), 136.59, 133.13 (d, J = 16.5 Hz), 132.01 (d, J = 23.0 Hz), 128.85 (d, J = 6.3Hz), 126.63, 114.55.

[0076] 31 P NMR (162 MHz, CDCl3) δ -5.15.

[0077] (3) Preparation of bisphosphine polymer support The preparation of the bisphosphine polymer support is basically the same as that in Example 1, except that: The 480 mg olefin-functionalized comonomer L4 in Example 1 was replaced with 480 mg olefin-functionalized comonomer L5.

[0078] (4) Preparation of the bisphosphine polymer-supported palladium catalyst material as in Example 1 The only difference from Example 1 is: The resulting bisphosphine polymer-supported palladium catalyst, which is denoted as catalyst F, is derived from different bisphosphine polymer supports.

[0079] Example 7 (1) Preparation of olefin-functionalized bidentate phosphine monomer L1 as in Example 1 (2) Preparation of olefin functionalized comonomer (L6) The preparation of the olefin-functionalized comonomer is basically the same as that in Example 1, except that: Replacing the anhydrous tetrahydrofuran (40 mL) of o-bromostyrene (S4, 6.04 g, 33 mmol) with the anhydrous tetrahydrofuran (40 mL) of p-bromostyrene (S2, 6.04 g, 33 mmol) yielded 2.4 g of white solid product, which was the olefin-functionalized comonomer L6, with a yield of 70%.

[0080] (3) Preparation of bisphosphine polymer support The preparation of the bisphosphine polymer support is basically the same as that in Example 1, except that: The 480 mg olefin-functionalized comonomer L4 in Example 1 was replaced with 480 mg olefin-functionalized comonomer L6.

[0081] (4) Preparation of the bisphosphine polymer-supported palladium catalyst material as in Example 1 The only difference from Example 1 is: The resulting bisphosphine polymer-supported palladium catalyst, which is denoted as catalyst G, is derived from the different bisphosphine polymer supports used.

[0082] Example 8 It is basically the same as Example 1, except that: In the preparation of the bisphosphine polymer support, 960 mg (2.82 mmol) of olefin-functionalized comonomer L4 was weighed out to replace 480 mg of olefin-functionalized comonomer L4. The resulting bisphosphine polymer-supported palladium catalyst is denoted as catalyst H.

[0083] Example 9 It is basically the same as Example 1, except that: In the bisphosphine polymer-supported palladium catalyst, PdCl2 (0.04 mmol) was used instead of Pd(acac)2 (0.04 mmol) as the active metal, and the resulting bisphosphine polymer-supported palladium catalyst is referred to as catalyst I.

[0084] Example 10 It is basically the same as Example 1, except that: In the bisphosphine polymer-supported palladium catalyst, palladium trifluoroacetate (0.04 mmol) was used instead of Pd(acac)2 (0.04 mmol) as the active component, and the resulting bisphosphine polymer-supported palladium catalyst is denoted as catalyst J.

[0085] Example 11 It is basically the same as Example 1, except that: In the bisphosphine polymer-supported palladium catalyst, palladium nitrate (0.04 mmol) was used instead of Pd(acac)2 (0.04 mmol) as the active material, and the resulting bisphosphine polymer-supported palladium catalyst was denoted as catalyst K.

[0086] Comparative Example 1 It is basically the same as Example 1, except that: Pd(acac)2 is not added as an active metal, i.e. step (4) is not included. The rest of the implementation process is the same as in Example 1. The obtained bisphosphine polymer support is used as the catalytic material and is denoted as catalyst L.

[0087] Comparative Example 2 Pd(acac)2 (10.32 mg, 0.04 mmol) was weighed and dissolved in 10.0 mL of tetrahydrofuran solvent. The olefin-functionalized bidentate phosphine monomer L1 (120 mg, 0.165 mmol) was added. The mixture was stirred at 25 °C under an inert atmosphere for 6 h. The solvent was removed under vacuum at room temperature to obtain an organometallic complex of bisphosphine ligand L1 coordinated with palladium, denoted as catalyst M.

[0088] Application Example 1 The catalysts prepared in Examples 1-11 and Comparative Examples 1-2 were used in the hydrogen esterification reaction of ethylene to illustrate the catalytic performance of different catalysts in the hydrogen esterification reaction of ethylene.

[0089] The reaction formula for the hydrogen esterification of ethylene is as follows: All catalytic evaluation experiments controlled the palladium feed amount to 1.0 µmol to ensure a consistent benchmark for comparing the performance of different catalysts. In a 100 mL high-pressure reactor, 25 mg of catalyst prepared in different examples (containing 1.0 µmol of Pd), 15.2 mg of p-toluenesulfonic acid monohydrate (0.08 mmol), and 4.0 mL of methanol (100 mmol) were added, respectively. At room temperature, the air in the reactor was purged four times with 1 MPa of Ar, then purged with ethylene (280 mg, 10 mmol) and CO until the total pressure reached 4 MPa. The high-pressure reactor was placed in the reactor and stirred at 100 °C for 24 h.

[0090] After the reaction was completed, the autoclave was cooled to room temperature and then placed in a refrigerator for 30 min to slowly release the pressure inside the autoclave. The reaction mixture was then diluted with methanol and 1,4-dioxane, and n-decane was added as an internal standard. The yield of methyl propionate was determined by gas chromatography (Agilent 7890A gas chromatograph, HP-5 capillary column, 5 wt.% phenyl, FID detector). The catalytic performance data of different catalysts are shown in Table 1.

[0091] Table 1 shows the catalytic performance of different catalysts in the hydrogen esterification reaction of ethylene. Note: TOF stands for Transition Frequency, which represents the number of molecules (or moles) of reactant converted per hour at each active site. It is a core indicator for measuring catalyst activity in catalytic chemistry.

[0092] As shown in Table 1, the heterogeneous catalyst prepared by this invention (Example 1) has significantly better activity than the corresponding homogeneous palladium complex system (Comparative Example 2). At the same time, it solves the problem that homogeneous catalysts cannot be recycled and reused. The following application test examples give examples of catalyst reuse.

[0093] Application Examples 2-12 Using the bisphosphine polymer-supported palladium catalyst prepared in Example 1 as catalyst A, in Application Examples 2-6, the process was the same as in Application Example 1, except that 10 mmol of different olefin substrates were added instead of 10 mmol of ethylene; in Application Examples 7-11, the process was the same as in Application Example 1, except that 100 mmol of different alcohol substrates were added instead of 100 mmol of methanol. The yields of organic carboxylic acid esters and the selectivity of straight-chain esters were determined by gas chromatography (Agilent 7890A gas chromatograph, HP-5 capillary column, 5 wt.% phenyl, FID detector). The different olefin and alcohol substrates and their reaction results are shown in Table 2. The reaction formulas for the hydrogen esterification of different olefin and alcohol substrates are as follows:

[0094] The olefins are specifically ethylene, propylene, butene, 1-octene, 3,3-dimethyl-1-butene, or styrene; the alcohols are specifically methanol, ethanol, butanol, isopropanol, or benzyl alcohol.

[0095] Table 2 shows the catalytic performance of catalyst A in the hydrogen esterification reactions of different olefin and alcohol substrates. Note: Straight-chain esters (%) represent the percentage of straight-chain esters among all product esters (including straight-chain and branched esters); "-" indicates that the produced esters are neither straight-chain nor branched.

[0096] As can be seen from Table 2, the catalytic material A prepared in this invention can be applied to the hydrogen esterification reaction of different olefin and alcohol substrates, and all exhibit good catalytic activity and straight-chain ester selectivity.

[0097] Application test cases Taking catalyst A prepared in Example 1 as an example, the reusability of the bisphosphine polymer-supported palladium catalyst in the catalytic hydrogen esterification reaction of ethylene is illustrated.

[0098] In a 100 mL high-pressure reactor, 25 mg of catalyst A prepared in Example 1 (containing 1.0 µmol of Pd), 15.2 mg of p-toluenesulfonic acid monohydrate (0.08 mmol), and 4.0 mL of methanol (100 mmol) were added, respectively. At room temperature, the air in the reactor was purged four times with 1 MPa of Ar, and then purged with ethylene (280 mg, 10 mmol) and CO until the total pressure reached 4 MPa. The high-pressure reactor was placed in the reactor and stirred for 24 h under heating at 100 °C.

[0099] After the reaction was completed, the autoclave was cooled to room temperature and then placed in a refrigerator for 30 min to slowly release the pressure inside. The reaction mixture was then diluted with methanol and 1,4-dioxane, and n-decane was added as an internal standard. The yield of methyl propionate was determined by gas chromatography (Agilent 7890A gas chromatograph, HP-5 capillary column, 5 wt.% phenyl, FID detector). The solid catalyst was centrifuged and washed three times with MeOH (10 mL) before being directly used in the next catalytic cycle. Reaction data for the reuse of catalyst A are shown in Table 3.

[0100] Table 3 shows the reusability of catalyst A in the hydrogen esterification reaction of ethylene. As can be seen from Table 3, the catalytic material A prepared in this invention can be reused ten times, and its catalytic activity can be well maintained.

[0101] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A bisphosphine polymer-supported palladium catalytic material, characterized in that, The material includes: a bisphosphine polymer support, and a palladium source loaded on the bisphosphine polymer support, wherein the palladium source is chelated and coordinated with bidentate phosphine ligands on the bisphosphine polymer support, and the palladium is dispersed in the form of atomic-level single sites; The bisphosphine polymer support is obtained by free radical polymerization of olefin-functionalized bidentate phosphine monomer and olefin-functionalized comonomer; The chemical structural formula of the olefin-functionalized bidentate phosphine monomer is shown in Formula I: In Formula I, X is selected from N; n is selected from integers from 1 to 5; R 1 Selected from phenyl, 2-pyridyl or tert-butyl; The chemical structural formula of the olefin-functionalized comonomer is shown in Formula II: 。 2. The bisphosphine polymer-supported palladium catalyst material according to claim 1, characterized in that, The chemical structural formula of the olefin-functionalized bidentate phosphine monomer is selected from any one of the following: 。 3. The bisphosphine polymer-supported palladium catalyst material according to claim 1, characterized in that, The chemical structural formula of the olefin-functionalized comonomer is selected from any one of the following: 。 4. The bisphosphine polymer-supported palladium catalyst material according to claim 1, characterized in that, The palladium source is selected from at least one of palladium chloride, palladium acetylacetone, palladium acetate, palladium di(acetonitrile) chloride, palladium triphenylphosphine chloride, palladium trifluoroacetate, palladium nitrate, tri(dibenzyl indeneacetone) dipalladium, or 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene) palladium dichloride.

5. The bisphosphine polymer-supported palladium catalyst material according to any one of claims 1 to 4, characterized in that, The molar ratio of the olefin-functionalized bidentate phosphine monomer to the olefin-functionalized comonomer is (0.05~1):1; Or / and, the mass ratio of the bisphosphine polymer support to the palladium source is (20~50):

1.

6. The method for preparing the bisphosphine polymer-supported palladium catalytic material according to any one of claims 1 to 5, characterized in that, The method includes: In an inert atmosphere, olefin-functionalized bidentate phosphine monomers as shown in Formula I, olefin-functionalized comonomers as shown in Formula II, free radical initiators, and a first organic solvent are mixed and subjected to free radical polymerization at 80~120℃ to obtain a bisphosphine polymer carrier. In an inert atmosphere, the bisphosphine polymer support and palladium metal are reacted in a second organic solvent at 20-60°C to obtain a bisphosphine polymer-supported palladium catalyst.

7. The preparation method according to claim 6, characterized in that, The first organic solvent and the second organic solvent are independently selected from at least one of ethanol, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, ethyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, n-hexane, toluene, anisole, dichloromethane, and chloroform; Or / and, the free radical initiator is selected from azobisisobutyronitrile, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide or methyl ethyl ketone peroxide; Or / and, the free radical polymerization reaction takes 1 to 72 h; Or / and, the coordination reaction takes 1 to 24 hours.

8. The application of the bisphosphine polymer-supported palladium catalyst as described in any one of claims 1 to 5 in the olefin hydrogen esterification reaction.

9. The application according to claim 8, characterized in that, The bisphosphine polymer-supported palladium catalyst is used to catalyze the olefin hydrogen esterification reaction of olefins, organic alcohols and CO. The olefin is selected from terminal olefins or terminal aryl olefins with a chain length of C1 to C8. The organic alcohol is selected from saturated alcohols or aryl alcohols with C1 to C5 chain lengths.

10. The application according to claim 8, characterized in that, The bisphosphine polymer-supported palladium catalyst, p-toluenesulfonic acid, and organic alcohol were placed in a high-pressure reactor, air was purged, and olefins and CO were introduced. The mixture was stirred and reacted under heating conditions at 100°C.

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