Ni-anderson polyoxometalate catalyst, its preparation method and application

Abstract

The application belongs to the field of catalytic materials and technology, and particularly relates to a Ni-Anderson polyoxometalate catalyst and a preparation method and application thereof. 26 The Ni-Anderson type polyoxometalate catalyst TBA2NiMo6 is obtained through one-step reaction of TBA4Mo8O, 1,1,1-tris(hydroxymethyl)ethane and Ni(OAc)22H2O, and is used in a coupling reaction of organic iodine and phenol to synthesize diphenyl ether. The application overcomes the technical difficulties of the coupling reaction, such as the use of noble metals and high-cost, toxic, air / moisture-sensitive high-usage organic ligands causing environmental pollution, the catalyst being unable to be recycled, and low catalyst conversion rate. The obtained catalyst has good catalytic activity, stability and durability, is green and mild, inexpensive and easy to prepare, and has a long service life. Moreover, the catalytic oxidation reaction can be easily expanded to a gram level, and has good industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalytic materials and technology, and particularly relates to a Ni-Anderson polyoxometalate catalyst and a preparation method and application thereof. BACKGROUND

[0002] Anderson-type heteropoly acid (general formula: [XM6O 24 ] n- ) is a kind of polyoxometalate inorganic compound with special structure and properties, and has been widely concerned by researchers due to its easy chemical modification and designability and high application value in the fields of materials, catalysis and medicine. In recent years, the application of Anderson-type heteropoly acid in catalyzing organic oxidation reaction gradually shows very important significance for the research of green catalytic process.

[0003] The progress of human society cannot be separated from the development of organic synthesis chemistry, however, in most organic synthesis reactions, not only the catalyst used is expensive and the reaction condition is harsh and dangerous, but also the by-products generated in the reaction often cause a certain degree of pollution to the environment, therefore, reducing or stopping the production of substances harmful to the ecological environment of human beings by using chemical technology and method is not only a difficulty in organic synthesis reaction, but also a focus of green chemistry research at present, and is one of the important directions of chemical development in the 21st century. With the development of the catalytic application of Anderson-type heteropoly acid, researchers found that in organic synthesis reaction, using Anderson-type polyoxometalate and its derivatives to replace traditional metal or non-metal catalysts for catalytic oxidation not only has high catalytic efficiency, but also generates less by-products in the catalytic process, which is a new green and efficient catalytic route friendly to the environment.

[0004] Therefore, it is a technical problem to be solved to find an Anderson-type polyoxometalate catalyst which can catalyze the synthesis of diaryl ether compounds. SUMMARY

[0005] Therefore, the first object of the present application is to provide an Anderson-type polyoxometalate catalyst which can catalyze the synthesis of diaryl ether compounds in view of the problems in the prior art.

[0006] In order to achieve the above object, the present application adopts the following technical solutions:

[0007] The Ni-Anderson polyoxometalate catalyst has a molecular formula of [(n-C4H9)4N]2{H2NiMo6O 18 [(OCH2)3CCH3]2}·(CH3CN)4 and a structural formula of:

[0008]

[0009] It is worth mentioning that the Ni-Anderson polyoxometalate catalyst disclosed in the application has simple chemical structure, small molecular weight, clear active site, outstanding economic advantages and stability, and good industrial application potential.

[0010] The second object of the application is to provide a preparation method of the Ni-Anderson polyoxometalate catalyst.

[0011] In order to achieve the above object, the application adopts the following technical scheme:

[0012] The preparation method of the Ni-Anderson polyoxometalate catalyst is prepared by one-step reaction of TBA4Mo8O, 1,1,1-tris(hydroxymethyl)ethane and Ni(OAc)2 2H2O in acetonitrile.

[0013] Preferably, the molar ratio of Ni(CH3COO)2 2H2O, TBA4Mo8O and (HOCH2)3CCH3 is 5:3:10, the concentration of TBA4Mo8O in acetonitrile is 0.022 mol / L, the reaction temperature is 85℃, and the reaction time is 12h. 26 26

[0014] Further preferably, in some embodiments, the preparation method further comprises cooling to room temperature after the reaction is completed, and standing for several days to volatilize, so as to obtain the Ni-Anderson polyoxometalate catalyst.

[0015] It is worth mentioning that the one-step synthesis method of the Ni-Anderson polyoxometalate catalyst disclosed in the application solves the technical difficulties of coupling reactions caused by the use of noble metals and high-cost, toxic, high-amount organic ligands sensitive to air / moisture, such as environmental pollution, catalyst cannot be recycled, low catalyst conversion rate, etc. The prepared catalyst shows good catalytic activity, stability and durability, is green and mild, is cheap, easy to prepare and recyclable, has long service life, and can be easily synthesized from ready-made chemicals in one step.

[0016] The third object of the application is to provide an application of the Ni-Anderson polyoxometalate catalyst.

[0017] The catalyst is used for synthesis of diaryl ether compounds.

[0018] ​​The application applies the Ni-Anderson type polyoxometalate catalyst to the coupling reaction of organic iodine and phenol to synthesize diphenyl ether, the target product is obtained with high yield, the reaction condition is mild, the catalyst loading is low, the large-scale reaction can be carried out with good effectiveness, and the reaction has good universality and versatility.

[0019] Further, the synthesis reaction of the diaryl ether compound uses aryl halide and substituted phenol as the reaction substrates, 1.5equ base and 1-3mol% Ni-Anderson polyoxometalate catalyst as the catalytic system, and is carried out in an organic solvent at 80-90°C for 12-16h.

[0020] Further, the reaction substrates and products include:

[0021]

[0022]

[0023] Further, the base includes KOH, K3PO4, K2CO3 or Cs2CO3; and the organic solvent includes DMF, DMSO, H2O, CH3CN, CH2Cl2 or toluene.

[0024] It is worth noting that the reaction principle of the application is that NiMo6 interacts with phenoxide ion to form complex A, which is added to the iodoaryl compound to form transition state B, and is converted into transition state C through halogen exchange. C is decomposed to obtain the diaryl ether product, and the complex D with catalytic activity is generated. Figure 5 )

[0025] Compared with the prior art, the application avoids the use of noble metal and high-toxicity organic ligand in the coupling reaction of organic iodine and phenol to synthesize diphenyl ether, avoids the environmental pollution caused by the high amount of air / water-sensitive organic ligand, reduces the industrial cost of the reaction, and meets the requirements of green chemistry and safe production. The Ni-Anderson type polyoxometalate catalyst used has good catalytic activity, stability and durability, is green and mild, is inexpensive and easy to prepare, and has a long service life. Moreover, the catalytic oxidation reaction can be easily scaled up to the gram level, and has good industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only are the embodiments of the application, and for those skilled in the art, other drawings can be obtained without creative labor based on the provided drawings

[0027] Figure 1 XRD spectrum of catalyst TBA2NiMo6 in the application embodiment 1.

[0028] Figure 2 FT-IR spectrum of catalyst TBA2NiMo6 in the application embodiment 1.

[0029] Figure 3 Stereoscopic structure diagram of catalyst TBA2NiMo6 in the application embodiment 1.

[0030] Figure 4 Electrochemical behavior of catalyst TBA2NiMo6 in the application application embodiment 1.

[0031] Figure 5 Reaction principle of the application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0033] Herein, the special word "embodiment" as "exemplary" explained any embodiment does not have to be interpreted as superior or better than other embodiments. In the performance index test of the embodiments of the application, unless otherwise specified, the conventional test method in the art is adopted. It should be understood that the terms described in the application are only for describing the specific embodiments, and are not used to limit the disclosure of the application.

[0034] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the application belongs; as the test methods and technical means not specially noted in the application are the experimental methods and technical means generally used by those skilled in the art.

[0035] In order to better illustrate the content of the application, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that without some specific details, the application can also be implemented. In the embodiments, some methods, means, instruments, equipment and the like which are well known to those skilled in the art are not described in detail, in order to highlight the main idea of the application.

[0036] The technical features disclosed in the embodiments of the application can be combined in any way without conflict, and the technical solutions obtained belong to the disclosure of the embodiments of the application.

[0037] The application is TBA4Mo8O26 A Ni-Anderson type polyoxometalate catalyst TBA2NiMo6 is prepared by one-step reaction of 1,1,1-tris(hydroxymethyl)ethane and Ni(OAc)22H2O, and is used in coupling reaction of organic iodine and phenol to synthesize diphenyl ether. The present application solves the technical difficulties in coupling reaction, such as use of noble metal and high cost, environmental pollution caused by high dosage of organic ligand which is toxic and sensitive to air / moisture, non-recovery of catalyst, and low conversion rate of catalyst. The obtained catalyst has good catalytic activity, stability and durability, is green and mild, inexpensive and easy to prepare, and has long service life. Moreover, the catalytic oxidation reaction can be easily scaled up to gram level, and has good industrial application potential.

[0038] In order to better understand the present application, the present application is further specifically described by the following examples, but it should not be understood as limiting the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the application are also regarded as falling within the protection scope of the present application.

[0039] Example 1 Preparation and characterization of Ni-Anderson polyoxometalate catalyst

[0040] A clean round-bottom flask (specification: 100 mL) was prepared, and Ni(CH3COO)2·2H2O (0.60 g, 2.75 mmol), TBA4Mo8O 26 (3.55 g, 1.65 mmol) and (HOCH2)3CCH3 (0.65 g, 5.5 mmol) were mixed in 75 mL acetonitrile, heated to reflux at 85°C for 12 h, cooled to room temperature, poured into a test tube and left to volatilize for several days to obtain blue crystals (2.08 g, Mo yield 52%).

[0041] The prepared catalyst TBA2NiMo6 was analyzed by XRD (as shown in Figure 1 ), FT-IR (as shown in Figure 2 ). FT-IR data: (KBr, cm-1): 3622, 2962, 2932, 2873, 1484, 1461, 1117, 1029, 939, 915, 895, 736, 708, 676, 552, 420. IR:í~max 51116m, 1043s, 1024m, 988w, 933vs, 915vs, 895s, 736sh, 708sh, 673vs. The stereochemical formula is shown in Figure 3 .

[0042] Application Example: Study on catalytic performance of catalyst TBA2NiMo6 in synthesis of diaryl ether compounds

[0043] Application Example 1

[0044] To verify the catalytic performance of the catalyst TBA2NiMo6for the synthesis of diaryl ether compounds, TBA4Mo8O 26 and Ni(OAc)22H2O were used as catalysts instead of NiMo6(Table 1), and the yield of the product 3a was poor under the same conditions. Only trace amounts of product were obtained when using nickel acetate, tris and molybdate precursors as catalysts. These results indicate that the MoO6units with shared edges can adjust the redox properties of the central nickel atom. The reaction of 1a in the absence of KOH and with 1.0 equivalent of phenol gave the yield of 2a under 23% and 60% conditions, respectively (Schemes 3.2c and 3.2e). The addition of 2.0 equivalents of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) had no inhibitory effect on the reaction under standard conditions, indicating that the conversion process did not occur via a free radical pathway.

[0045] Table 1

[0046]

[0047] Further, the catalytic performance of the catalyst was verified by electrochemical behavior test. With glassy carbon as working electrode, Pt as counter electrode, Ag / AgCl (saturated KCl) as reference electrode, and the scan rate of 100 mV·s -1 , the cyclic voltammograms of various metal catalysts in 0.1M n Bu4NBF4 / MeCN are shown in Figure 4 Figure 1. The oxidation potential of NiMo6in pure MeCN is about +2.52V, which is higher than that of TBA4Mo8O 26 (+1.57V) and Ni(OAc)22H2O (+1.49V). The electrochemical behavior of the catalyst also proves that the MoO6units with shared edges can adjust the redox properties of the central nickel atom.

[0048] Application Example 2

[0049] Using 4-nitroiodobenzene 1a and phenol 2a as substrates, 0.5 mol% NiMo6as catalyst, the reaction was carried out at 90°C under air atmosphere for 16h, and the yield of the product 4-nitrodiphenyl ether was tested. The adjusted solvent, the type of base and the reaction yield are shown in Table 2. It can be seen that using DMF as solvent, the yield of 4-nitrodiphenyl ether product 2a is 94%. Other solvents such as DMSO, H2O, CH3CN, CH2Cl2and toluene were also tested, but the effect was inferior to DMF. In addition, the use of other bases (K3PO4, K2CO3, Cs2CO3and NaOH) instead of KOH resulted in a significant decrease in reaction efficiency. In addition, when the amount of catalyst, reaction temperature and / or reaction time were changed, the product yield was reduced.

[0050] Table 2 Optimization of the reaction conditions a

[0051]

[0052]

[0053]

[0054] a Conditions: 1a (0.6 mmol), 2a (0.5 mmol), KOH (1.5 mmol), NiMo6 catalyst (2 mol%), DMF (1.0 mL), 90 °C, 16 h, Air. b Isolated yield. c 6 h.

[0055] Application Example 3:

[0056] The generality of the organic iodide removal reaction under the optimized conditions was evaluated (Table 3). It can be seen that various substituents on the benzene ring, whether electron-donating or electron-withdrawing, are compatible with the reaction conditions to provide the corresponding products in good to excellent yields (3a-3d). In addition, the position of the group has no significant effect on the yield of the removal product (3e-3p, 3r).

[0057] Table 3 Synthesis of biaryl ethers a,b

[0058]

[0059]

[0060] a Conditions: 1a (0.5 mmol), 2a (1.0 mmol), KOH (1.5 mmol), NiMo6 catalyst (2 mol%), DMF (1.0 mL), 90 °C, 16 h, Air. b Isolated yield.

[0061] Application Example 4:

[0062] Further exploration of the reaction scope of various aryl iodides with substituted phenols. The optimized conditions were applied to the reaction of iodobenzene, which did not work. Under the same optimized conditions, experiments were carried out using electron-deficient aryl iodides 4-iodobenzonitrile and 4-iodobenzaldehyde, but the experimental results were not ideal. However, by optimizing the time, the yield can be improved to 78% (Table 4). The time was extended from 16 h to 24 h to obtain the corresponding product and yield, as shown in Table 4. The reactions of 4-iodobenzonitrile and 4-iodobenzaldehyde with different phenols used improved conditions (Table 4). The electronic properties of the substituents on the phenol have an effect on the reaction yield, among which the yield of the phenol containing p-methylphenol, p-cyanophenol and the like electron-withdrawing groups is relatively low.

[0063] Table 4 Synthesis of diorganyl ditellurides a,b

[0064]

[0065]

[0066] a Conditions: 1a (0.6 mmol), 2a (0.5 mmol), KOH (1.5 mmol), NiMo6 catalyst (2 mol%), DMF (1.0 mL), 90 °C, 24 h, Air. b Isolated yield.

[0067] Application Example 5 Scale-up reaction

[0068] In order to further prove the effectiveness of the method, the application carried out reaction scale-up. The reaction of 5.0 mmol scale was carried out smoothly, and the yield of 2a was 70% (Table 5). Interestingly, at 340TON, low catalyst loading (1 mol%), 25 mmol and 50 mmol large scale reactions also obtained 64.5%-53% yield, which expanded the work, provided a successful example for the application of the catalyst in large-scale production, and showed that it has certain industrial application value.

[0069] Table 5 Reaction scale-up data

[0070]

[0071] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Ni-Anderson polyoxometalate catalyst for the synthesis of diaryl ether compounds, characterized by, [(n-C4H9)4N]2{H2NiMo6O 18 [(OCH2)3CCH3]2}·(CH3CN)4.

2. A process for the preparation of the Ni-Anderson polyoxometalate catalyst according to claim 1, characterized in that, TBA4Mo80, 1,1,1-tris(hydroxymethyl)ethane and Ni(OAc)2 2H2O in acetonitrile by one step reaction, said Ni(CH3COO)2 2H2O, TBA4Mo80 26 and (HOCH2)3CCH3 in a molar ratio of 5:3:10, TBA4Mo80 26 in acetonitrile at a concentration of 0.022 mol / L, the reaction temperature is 85°C, and the reaction time is 12 h.

3. The production method according to claim 2, characterized by, After the reaction is completed, it is cooled to room temperature and left to stand for several days to volatilize, to obtain the Ni-Anderson polyoxometalate catalyst.

4. Use of a Ni-Anderson polyoxometalate catalyst according to claim 1, characterized in that, The catalyst is used for synthesis of diaryl ether compounds.

5. Use according to claim 4, characterized in that, The synthesis reaction of the diaryl ether compound uses aryl halide and substituted phenol as the reaction substrates, 1.5 equ base and 1-3 mol% Ni-Anderson polyoxometalate catalyst as the catalytic system, and is reacted in an organic solvent at 80-90°C for 12-16 h.

6. Use according to claim 5, characterized in that, The base includes KOH, K3PO4, K2CO3 or Cs2CO3; and the organic solvent includes DMF, DMSO, H2O, CH3CN, CH2Cl2 or toluene.

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