Preparation and application of regular unit point palladium catalyst
By preparing regular unit-point palladium catalysts with monodispersed triangular cube morphology, the problems of poor single-atomicity and recycling of unit-point catalysts in the prior art are solved, and efficient catalytic and low-cost catalyst preparation are achieved, suitable for Sonogashira Coupling reactions and other chemical reactions.
Patent Information
- Application Number
- CN202411274738.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2024-12-17
AI Technical Summary
During the synthesis of existing unit-point catalysts, there are problems such as difficulty in ensuring single-atomicity, poor recycling and metal residue contamination, especially in the Sonogashira coupling reaction, the catalyst is difficult to separate, recover and reuse.
By preparing a regular unit-point palladium catalyst with monodispersed triangular cube morphology, the chemical composition is Pd(C24H31P)2Cl2, the palladium metal atom has a 4-coordination structure and is connected to the phosphine ligand and chlorine atom, using 2-(dicyclohexyl) As a ligand, phosphine)biphenyl achieves clear and clear palladium active center and high crystallinity of the catalyst.
It realizes efficient preparation and recycling of catalysts, has good catalytic activity and selectivity, is suitable for Sonogashira coupling reactions and other chemical reactions, and is low toxicity, low cost, and is suitable for industrial production.
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Figure CN119143811A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of catalyst material preparation, in particular to the preparation and application of a regular unit-site palladium catalyst. Background Art
[0002] The Sonogashira coupling reaction is a coupling reaction of aryl halides or vinyl halides with terminal acetylene under the catalysis of transition metals such as palladium. It is one of the most important carbon-carbon bond formation reactions in organic synthesis and is often used in the synthesis of natural products, bioactive molecules, heterocycles, molecular electronics, dendrimers, conjugated polymers or nanostructures. Generally, the Sonogashira coupling reaction is catalyzed by homogeneous palladium complex catalysts and ligands. Despite the advantages of high activity, high selectivity and high yield, most homogeneous catalysts still have the toxicity of the ligands used and the risk of metal residue contamination, as well as the disadvantages that the catalyst cannot be separated and recovered and is difficult to reuse. In recent years, heterogeneous metal catalysis has attracted widespread attention due to its excellent catalytic activity, wide substrate range and easy recovery. Heterogeneous metal catalysts are easy to recover by filtration or centrifugation, allowing the catalyst to be reused after the reaction is completed.
[0003] Metal catalysts, especially transition metal catalysts, have excellent catalytic activity and can significantly reduce the activation energy of chemical reactions and improve reaction efficiency. Transition metals can present a variety of oxidation states, which provides flexibility for their diverse chemical participation in the catalytic process. By precisely regulating the morphology and function of transition metal catalysts, the needs of specific catalytic reactions can be met. Palladium-based catalysts play an important role in the preparation of fuel cell materials, hydrogen storage materials, and heterogeneous catalytic materials due to their good chemical stability and conductivity. They are also very important in the hydrogen evolution reaction (HER), oxygen evolution reaction (HOR), and CO 2 It has also been widely studied in many applications such as reduction reaction (CO2RR). However, the synthesis of many single-site catalysts still has the following problems: 1. In order to ensure the single atomicity of the single-site catalyst, acid washing is often required to remove the particulate metal. 2. The catalytic site of the single-site catalyst may be deactivated during the recycling process, and the recycling performance is poor. Summary of the invention
[0004] The purpose of the present invention is to provide a preparation method and use of a regular unit-site palladium catalyst to solve the above-mentioned problems in the background technology. The present invention discloses a novel unit-site palladium-based catalyst. Through the control means of the present invention, the crystal structure of the regular unit-site palladium catalyst can present a monodispersed triclinic cubic morphology at a mesoscopic scale. The catalyst has excellent crystallinity, a flat surface, regular and single coordination, a unit-site palladium active center, and a clear and definite reaction site.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] One of the technical solutions of the present invention is to provide a regular unit-site palladium catalyst, wherein the regular unit-site palladium catalyst is a crystalline material, and the chemical composition is Pd(C 24 H 31 P) 2 Cl 2 , belongs to the triclinic cubic system, in which the palladium metal atom is in a 4-coordinate structure, connected to two phosphine ligands and two chlorine atoms respectively, and there is a π-π conjugated superposition effect between the unit cells. The unit cell parameters are α=108.64(5)°,β=92.16(4)°,γ=104.13(4)°; the phosphine ligand is 2-(dicyclohexylphosphino)biphenyl.
[0007] Preferably, in the regular unit-site palladium catalyst, the Pd content is 12.11 wt % and the P content is 7 wt %.
[0008] Preferably, the crystals of the regular unit-site palladium catalyst are monodispersed triclinic cubes with a size of 0.5-2 μm.
[0009] More preferably, when the crystal structure remains unchanged, that is, when the content of each element remains unchanged, the size of the truncated cube is 10-20 μm, and the size of the regular octahedron is 15-20 μm.
[0010] The second technical solution of the present invention is to provide a method for preparing the above-mentioned regular unit-site palladium catalyst, comprising the following steps:
[0011] dissolving a palladium salt in water to obtain a first solution;
[0012] dissolving 2-(dicyclohexylphosphino)biphenyl in a solvent to obtain a second solution;
[0013] The first solution, the second solution and the phase transfer catalyst are mixed to obtain a premixed solution, and the premixed solution is reacted to obtain the regular unit-site palladium catalyst;
[0014] The palladium salt is palladium chloride.
[0015] Preferably, after the reaction is completed, washing and drying steps are further included; the washing includes washing with ethanol and dichloromethane alternately.
[0016] Preferably, the solvent is methanol, ethanol or dichloromethane.
[0017] Preferably, the concentration of the palladium salt in the first solution is 0.05-0.1M; the concentration of 2-(dicyclohexylphosphino)biphenyl in the second solution is 25-35M.
[0018] Preferably, the phase transfer catalyst is tetraoctylammonium bromide (TOAB).
[0019] Preferably, the mass ratio of the palladium salt to 2-(dicyclohexylphosphino)biphenyl in the premix is 1:6-1:10.
[0020] Preferably, the reaction temperature is 20-25°C and the reaction time is 1-12h.
[0021] The third technical solution of the present invention is to provide an application of the above-mentioned regular unit-site palladium catalyst in catalyzing the Sonogashira coupling reaction.
[0022] The fourth technical solution of the present invention is to provide an application of the above-mentioned regular unit-site palladium catalyst in catalyzing the reaction of bromobenzene and phenylacetylene to produce diphenylacetylene.
[0023] The beneficial technical effects of the present invention are as follows:
[0024] The invention discloses a novel single-site palladium-based catalyst. The preparation method of the invention can make the crystal structure of the regular single-site palladium catalyst present a monodispersed triclinic cubic morphology at a mesoscopic scale. The catalyst has excellent crystallinity, a flat surface, regular and single coordination, a single-site palladium active center, and a clear and definite reaction site.
[0025] The preparation method of the present invention is simple and rapid, does not require pyrolysis, and can achieve mass production. The single-site palladium-based catalyst of the present invention has strong versatility, low raw material cost, wide sources, low toxicity, wide reaction conditions, high safety, and is suitable for industrial expansion production.
[0026] The regular single-site palladium catalyst prepared by the invention can be used for catalyzing the Sonogashira coupling reaction, and has good selectivity and conversion rate in the process of catalyzing the reaction of bromobenzene and phenylacetylene to generate diphenylacetylene. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0028] Figure 1 The UV spectrum and physical picture of the product in Example 1 are shown below.
[0029] Figure 2 This is the X-ray powder diffraction pattern of the product in Example 1.
[0030] Figure 3Schematic diagram of the single crystal structure of the product of Example 1.
[0031] Figure 4 This is the X-ray single crystal diffraction crystal data table of the product in Example 1.
[0032] Figure 5 Schematic diagram of the π···π conjugation of the product in Example 1.
[0033] Figure 6 This is a scanning electron microscope photograph of the product of Example 1. DETAILED DESCRIPTION
[0034] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.
[0035] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.
[0036] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.
[0037] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.
[0038] The "normal temperature" in the present invention is 20-25°C unless otherwise specified.
[0039] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.
[0040] Example 1
[0041] A method for preparing a regular unit-site palladium catalyst:
[0042] Dissolve 1 g of palladium chloride in 20 mL of water, and the resulting black solution is the first solution.
[0043] 175 mg of 2-(dicyclohexylphosphino)biphenyl was dissolved in 15 mL of dichloromethane to obtain a second solution.
[0044] Mix 500 μL of the first solution, 15 mL of the second solution and 0.135 g of tetra-n-octylammonium bromide to obtain a premixed solution, react at room temperature for 4 hours, then separate the solid and liquid by centrifugation, collect the solid product, and dry it in an oven at 30°C to obtain a regular unit-site palladium catalyst (dichlorobis(cyclohexylphosphinobiphenyl)palladium, denoted as cat.).
[0045] The calculation showed that the catalyst yield was 85%, the Pd content in the catalyst was 12.11wt%, and the P content was 7wt%.
[0046] Effect verification
[0047] (1) Characterization of the product of Example 1
[0048] Figure 1 The UV spectrum and physical picture of the product in Example 1 are shown below.
[0049] Figure 2 This is the X-ray powder diffraction pattern of the product in Example 1.
[0050] Figure 2 In the figure, the ordinate represents the relative diffraction intensity.
[0051] Figure 2 It can be seen that the prepared single-atom palladium crystals have excellent crystallinity and are free of impurities, which is consistent with the simulated XRD data.
[0052] Figure 3 Schematic diagram of the single crystal structure of the product of Example 1.
[0053] Figure 3 It can be seen that the single-atom palladium crystal obtained belongs to the triclinic cubic crystal system, the metal atoms have a 4-coordinate structure, and the palladium atoms are connected to two phosphine ligands and two chlorine atoms, which are connected by π-π conjugated superposition.
[0054] Figure 4 This is the X-ray single crystal diffraction crystal data table of the product in Example 1.
[0055] Depend on Figure 4 It can be seen that the unit cell parameters are α=108.64(5)°, β=92.16(4)°, γ=104.13(4)°.
[0056] Figure 5 Schematic diagram of the π···π conjugation of the product in Example 1.
[0057] Figure 5 It can be seen that the unit cells of the prepared single-atom palladium crystals are connected by π-π conjugated superposition.
[0058] Figure 6 This is a scanning electron microscope photograph of the product of Example 1.
[0059] Figure 6 It can be seen that the prepared crystals present triclinic cubes with sizes ranging from 0.5 to 2 μm.
[0060] (2) The Sonogashira coupling reaction test was carried out using the regular single-site palladium catalyst prepared in Example 1. The test conditions are: bromobenzene, phenylacetylene, base and the product of Example 1 (the catalyst amount is 3 mg) were mixed in a solvent, reacted at 100° C. for 24 hours, and the catalytic reaction was completed. The equation for the catalytic reaction is:
[0061]
[0062] Some test conditions and results are shown in Table 1.
[0063] Table 1
[0064]
[0065] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.
Claims
1. A regular unit-site palladium catalyst, characterized in that: The regular unit-site palladium catalyst is a crystalline material, and its chemical composition is Pd(C 24 H 31 P)2Cl2 belongs to the triclinic cubic system, in which the palladium metal atom is in a 4-coordinate structure, connected to two phosphine ligands and two chlorine atoms respectively, and there is a π-π conjugated superposition effect between the unit cells. The unit cell parameters are α=108.64(5)°,β=92.16(4)°,γ=104.13(4)°; the phosphine ligand is 2-(dicyclohexylphosphino)biphenyl.
2. The regular unit site palladium catalyst according to claim 1, characterized in that The crystals of the regular unit-site palladium catalyst are monodispersed triclinic cubes with a size of 0.5-2 μm.
3. A method for preparing a regular unit-site palladium catalyst according to claim 1 or 2, characterized in that: The following steps are involved: dissolving a palladium salt in water to obtain a first solution; dissolving 2-(dicyclohexylphosphino)biphenyl in a solvent to obtain a second solution; The first solution, the second solution and the phase transfer catalyst are mixed to obtain a premixed solution, and the premixed solution is reacted to obtain the regular unit-site palladium catalyst; The palladium salt is palladium chloride.
4. The preparation method according to claim 3, characterized in that: The solvent is methanol, ethanol or dichloromethane.
5. The preparation method according to claim 3, characterized in that: The concentration of the palladium salt in the first solution is 0.05-0.1M; the concentration of the 2-(dicyclohexylphosphino)biphenyl in the second solution is 25-35M.
6. The preparation method according to claim 3, characterized in that: The phase transfer catalyst is tetraoctylammonium bromide.
7. The preparation method according to claim 3, characterized in that: The mass ratio of the palladium salt to 2-(dicyclohexylphosphino)biphenyl in the premix is 1:6-1:
10.
8. The preparation method according to claim 3, characterized in that: The reaction temperature is 20-25°C and the reaction time is 1-12h.
9. Use of the regular single-site palladium catalyst according to claim 1 or 2 in catalyzing a Sonogashira coupling reaction.
10. Use of the regular single-site palladium catalyst according to claim 1 or 2 in catalyzing the reaction of bromobenzene and phenylacetylene to produce diphenylacetylene.