Continuous synthesis method of sulfonepyraclostrobin

Abstract

The present invention provides a continuous synthesis method of sulfonepyrazoline. The continuous synthesis method includes: the raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazole-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, catalyst and organic solvent are passed into a continuous photochemical reactor for continuous oxidation reaction to obtain a reaction solution; the reaction solution is quenched and purified in sequence to obtain sulfonepyrazoline. The introduction of light helps to shorten the time of the oxidation reaction from the original hour level to the minute level, and the reaction time is greatly shortened, thereby helping to improve the production efficiency of sulfonepyrazoline; the use of a continuous reactor helps to accurately control the temperature of the oxidation reaction, essentially reducing the danger of materials and reactions, and effectively solving the problem of large batch reaction heat release and high process risk.

Description

Technical Field

[0001] The invention relates to the technical field of sulfonepyraclostrobin, and in particular to a continuous synthesis method of sulfonepyraclostrobin. Background Art

[0002] Pyroxasulfone, also known as rock-killing sulfone, has a molecular formula of C 12 H 14 F5N3O4S, CAS: 447399-55-5, is a white crystalline powder at room temperature. It is a new type of pyrazole selective herbicide. It was launched in 2011. It is a new type of pre-emergence herbicide that can interfere with C 18 The chain is extended, inhibiting the synthesis of very long chain fatty acids (VLCFA). Sulfonepyraclostrobin is mainly absorbed into the target plant through the plant root or apical meristem, and is mainly effective against annual grass weeds and some broadleaf weeds.

[0003] At present, the production process of sulfonepyraclostrobin is as follows:

[0004]

[0005] In the presence of a catalyst, the raw material 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole is subjected to an oxidation reaction with an oxidant in a solvent to obtain the product sulfonepyrazoline. However, the above oxidation reaction is a high-risk process, the heat generated by the reaction is large and the reaction is violent, and it involves the use of controlled materials, and the process risk is high; and the reaction time of the oxidation reaction is long, usually 5h~24h, and the production efficiency is low. Summary of the invention

[0006] The main purpose of the present invention is to provide a continuous synthesis method of sulfonepyraclostrobin to solve the problems of low efficiency and high safety risk in the preparation method of sulfonepyraclostrobin in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a continuous synthesis method of sulfonepyraclostrobin is provided, and the continuous synthesis method comprises: introducing raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, a catalyst and an organic solvent into a continuous photochemical reactor for continuous oxidation reaction to obtain a reaction liquid; quenching and purifying the reaction liquid in sequence to obtain sulfonepyraclostrobin; the catalyst is a tungsten-containing compound.

[0008] Furthermore, a light source is provided in the above-mentioned continuous photochemical reactor, and the raw materials are processed under the irradiation of the light source, and the light intensity of the light source is 30mw / cm²~300mw / cm²; and / or, the wavelength of the light source is a single wavelength, and the wavelength is 275~590nm.

[0009] Furthermore, the wavelength is 335-480 nm; and / or the light source is selected from any one or more of LED, mercury lamp, xenon lamp, laser lamp and fluorescent lamp.

[0010] Furthermore, the molar ratio of the above-mentioned 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide and catalyst is 1:2~4:0.03~0.1.

[0011] Furthermore, the above raw materials also include a photosensitizer, and the equivalent ratio of the photosensitizer to the catalyst is 1:0.2~1.

[0012] Furthermore, the photosensitizer is selected from any one or more of benzophenone, xanthanone, acridinium salt and 1,2,3,5-tetrakis(carbazole-9-yl)-4,6-dicyanobenzene; and / or the catalyst is selected from any one or more of sodium tungstate, tungstic acid and tungsten oxide.

[0013] Furthermore, the photosensitizer is a combination of benzophenone and xanthenone, and the molar ratio of benzophenone to xanthenone is 1:0.1~1; and / or the catalyst is a combination of sodium tungstate and tungstic acid, and the molar ratio of sodium tungstate to tungstic acid is 1:0.5~1.

[0014] Furthermore, the reaction temperature in the above-mentioned continuous photochemical reactor is 30-60° C.; and / or the reaction residence time in the continuous photochemical reactor is 1-10 min.

[0015] Furthermore, the organic solvent is selected from any one or more of tetrahydrofuran, acetonitrile, dichloromethane, dichloroethane and chloroform.

[0016] Furthermore, the above-mentioned continuous photochemical reactor also includes a reactor, and the reactor is a tubular reactor.

[0017] By applying the technical solution of the present invention, raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, a catalyst and an organic solvent are introduced into a continuous photochemical reactor for oxidation reaction. On the one hand, the introduction of light helps to shorten the oxidation reaction time from the original hour level to the minute level, and the reaction time is greatly shortened, thereby helping to improve the production efficiency of sulfonepyraclostrobin; on the other hand, the use of a continuous reactor helps to accurately control the temperature of the oxidation reaction, essentially reducing the danger of materials and reactions, and effectively solving the problem of large batch reaction heat release and high process risk. The use of tungsten-containing compounds as catalysts helps to improve the selectivity of the oxidation reaction, thereby helping to improve the yield of sulfonepyraclostrobin. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 The schematic diagram of the structure of the continuous reaction system of sulfonepyraclostrobin in Example 1 of the present application is shown;

[0020] Figure 2 The gas chromatogram of pyraclostrobin in Example 1 of the present application is shown.

[0021] The above drawings include the following reference numerals:

[0022] 1. Catalyst solution supply unit; 2. Reactant supply unit; 3. Hydrogen peroxide supply unit; 4. First plunger pump; 5. Continuous photochemical reactor; 6. Continuous quenching unit; 7. Continuous crystallization unit; 8. Filtration, elution and drying unit; 9. Second plunger pump; 10. Third plunger pump. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] As analyzed in the background technology of the present application, the preparation method of sulfonepyraclostrobin in the prior art has the problems of low efficiency and high safety risks. In order to solve the above problems, the present application provides a continuous synthesis method of sulfonepyraclostrobin.

[0025] In a typical embodiment of the present application, a continuous synthesis method of sulfonepyraclostrobin is provided, which comprises: introducing raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, a catalyst and an organic solvent into a continuous photochemical reactor for continuous oxidation reaction to obtain a reaction liquid; quenching and purifying the reaction liquid in sequence to obtain sulfonepyraclostrobin; the catalyst is a tungsten-containing compound.

[0026] By introducing raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, catalyst and organic solvent into a continuous photochemical reactor for oxidation reaction, on the one hand, the introduction of light helps to shorten the oxidation reaction time from the original hour level to the minute level, and the reaction time is greatly shortened, thereby helping to improve the production efficiency of sulfonepyraclostrobin; on the other hand, the use of a continuous reactor helps to accurately control the temperature of the oxidation reaction, essentially reducing the danger of materials and reactions, and effectively solving the problem of large heat release and high process risk in batch reactions. The use of tungsten-containing compounds as catalysts helps to improve the selectivity of the oxidation reaction, thereby helping to improve the yield of sulfonepyraclostrobin.

[0027] The above reaction solution is quenched in a continuous quenching unit, including but not limited to, the continuous quenching unit is a quenching bottle or a quenching tank, the quenching bottle or the quenching tank contains a quencher, the quencher includes but is not limited to any one or more of sodium sulfite, sodium thiosulfate, sodium pyrosulfate and sodium bisulfite, and the molar ratio of the quencher to 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole is preferably 1:0.5~0.7.

[0028] In a preferred embodiment, the purification process comprises: crystallizing the quenched product in a continuous crystallization unit, filtering, eluting and drying the precipitated crystals in a filtering, leaching and drying unit to obtain sulfonepyraclostrobin. In addition, including but not limited to, the continuous crystallization unit is a condenser, and the filtering, leaching and drying unit is a centrifuge and an oven connected in sequence.

[0029] In one embodiment of the present application, a light source is provided in the above-mentioned continuous photochemical reactor, and the raw materials are processed under the irradiation of the light source, and the light intensity of the light source is 30mw / cm²~300mw / cm²; and / or, the wavelength of the light source is a single wavelength, and the wavelength is 275~590nm;

[0030] Too high an illumination intensity of the light source is not conducive to reducing the generation of by-products, and too low an illumination intensity of the light source is not conducive to shortening the reaction time. It is preferred to control the illumination intensity of the light source within the above range, which helps to improve the yield and purity of sulfonepyraclostrobin while shortening the reaction time, thereby helping to improve the production efficiency and production cost of sulfonepyraclostrobin. In order to improve the absorption efficiency of light by the reactants, it is preferred to control the wavelength of the light source to a single wavelength, and the wavelength is 275 to 590 nm.

[0031] In one embodiment of the present application, the wavelength is 335-480 nm; and / or the light source is selected from any one or more of LED, mercury lamp, xenon lamp, laser lamp and fluorescent lamp.

[0032] Preferably, the wavelength is controlled within the above range, which helps to further improve the utilization rate of light by the reactants, thereby helping to further improve the yield and purity of sulfonepyraclostrobin. Preferably, the type of light source is controlled within the above range, which helps to enrich the selectivity of the light source.

[0033] In order to improve the yield of sulfonepyraclostrobin, in one embodiment of the present application, the molar ratio of the above-mentioned 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide and catalyst is preferably 1:2~4:0.03~0.1.

[0034] In one embodiment of the present application, the above-mentioned raw materials also include a photosensitizer, and the equivalent ratio of the photosensitizer to the catalyst is 1:0.2~1.

[0035] The addition of photosensitizer helps to promote the activation of reactants. The photosensitizer absorbs photons and enters an electronic excited state, resulting in it having strong redox properties. It can quickly transfer electrons to electron-deficient acceptors, or accept electrons from electron-rich donors. The reaction cycle includes two pathways, oxidation and reduction. The final result is the generation of a pair of reactive radical ions comprising an oxidation donor and a reduction acceptor, thereby helping to further shorten the reaction time, and thus helping to improve the production efficiency of sulfonepyraclostrobin. A too low equivalent ratio of photosensitizer to catalyst is not conducive to shortening the reaction time, and a too high equivalent ratio of photosensitizer to catalyst is not conducive to improving the purity of sulfonepyraclostrobin. It is preferred to control the equivalent ratio of photosensitizer to catalyst within the above range, which helps to increase the reaction rate and reduce the impurity content.

[0036] In one embodiment of the present application, the photosensitizer is selected from any one or more of benzophenone, xanthanone, acridinium salt and 1,2,3,5-tetrakis(carbazole-9-yl)-4,6-dicyanobenzene; and / or the catalyst is selected from any one or more of sodium tungstate, tungstic acid and tungsten oxide.

[0037] Preferably, the type of photosensitizer is controlled within the above range, which helps to further shorten the reaction time, thereby helping to improve the reaction efficiency of the oxidation reaction. Preferably, the type of catalyst is controlled within the above range, which helps to improve the selectivity of the oxidation reaction, thereby helping to improve the yield of sulfonepyraclostrobin.

[0038] In order to further shorten the reaction time and improve the yield and purity of sulfonepyraclostrobin, in one embodiment of the present application, it is preferred that the above-mentioned photosensitizer is a combination of benzophenone and xanthon, and the molar ratio of benzophenone to xanthon is 1:0.1~1; and / or, the catalyst is a combination of sodium tungstate and tungstic acid, and the molar ratio of sodium tungstate to tungstic acid is 1:0.5~1.

[0039] In one embodiment of the present application, the reaction temperature in the above-mentioned continuous photochemical reactor is 30-60° C.; and / or the reaction residence time in the continuous photochemical reactor is 1-10 min.

[0040] Since light is introduced into the oxidation reaction process of the present application, the reaction of the present application does not require too high a reaction temperature and too long a reaction time to produce pyraclostrobin with high purity and yield.

[0041] In order to improve the solubility of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole and the catalyst in the organic solvent, thereby improving the efficiency of the oxidation reaction, in one embodiment of the present application, the organic solvent is preferably selected from any one or more of tetrahydrofuran, acetonitrile, dichloromethane, dichloroethane and chloroform.

[0042] In order to improve the utilization rate of the light source and control the temperature of the reaction, in one embodiment of the present application, it is preferred that the above-mentioned continuous photochemical reactor also includes a reactor, the reactor is a tubular reactor, and the number of tubular reactors is preferably 1 to 3, and the tubular reactors are connected in series.

[0043] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0044] Example 1

[0045] Use Figure 1The sulfonepyrazoline reaction system shown in the figure is used to prepare sulfonepyrazoline. Specifically, a sodium tungstate solution is prepared in the catalyst solution supply unit 1, and the concentration of the sodium tungstate solution is 1.05 mol / L. A 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole solution is prepared in the reactant supply unit 2, and the solvent is acetonitrile. 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole The concentration of the solution is 0.51 mol / L, a hydrogen peroxide solution is prepared in the hydrogen peroxide supply unit 3, and the concentration of the hydrogen peroxide is 50%. The sodium tungstate solution enters the continuous photochemical reactor 5 through the first plunger pump 4 at a flow rate of 0.3 g / min, and the 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole solution enters the continuous photochemical reactor 5 through the second plunger pump 9 at a flow rate of 1.2 g / min, and the hydrogen peroxide solution enters the continuous photochemical reactor 5 through the third plunger pump 10 at a flow rate of 1 .5g / min flow rate into the continuous photochemical reactor 5, the continuous photochemical reactor 5 is composed of a tubular reactor and a light source, the light source is an LED lamp, the light intensity is 200mw / cm², the wavelength is 335nm, the continuous photochemical reactor 5 is controlled to have a continuous oxidation reaction at a molar ratio of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide and sodium tungstate of 1:3:0.06, the reaction temperature is controlled to be 50°C, and the reaction residence time is 5mi n, then the reactants are passed into a continuous quenching unit 6 (quenching tank) for quenching, the quenching agent in the quenching tank is sodium sulfite, and the molar ratio of sodium sulfite to 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole is controlled to be 1.0:0.5, and the quenched product is passed into a continuous crystallization unit 7 (condenser) for cooling and crystallization, and the crystallized product is passed into a filtering, leaching and drying unit 8 (a centrifuge and an oven connected in sequence) for filtering, leaching and drying in turn to obtain sulfonepyraclostrobin.

[0046] Example 2

[0047] The difference from Example 1 is that the wavelength is 365 nm, and sulfonepyraclostrobin is finally obtained.

[0048] Example 3

[0049] The difference from Example 1 is that the wavelength is 480 nm, and sulfonepyraclostrobin is finally obtained.

[0050] Example 4

[0051] The difference from Example 1 is that the wavelength is 590 nm, and sulfonepyraclostrobin is finally obtained.

[0052] Example 5

[0053] The difference from Example 1 is that the wavelength is 275 nm, and sulfonepyraclostrobin is finally obtained.

[0054] Example 6

[0055] The difference from Example 1 is that the illumination intensity is 300 mw / cm², and sulfonepyraclostrobin is finally obtained.

[0056] Example 7

[0057] The difference from Example 1 is that the illumination intensity is 30 mw / cm², and sulfonepyraclostrobin is finally obtained.

[0058] Example 8

[0059] The difference from Example 1 is that the illumination intensity is 500 mw / cm², and sulfonepyraclostrobin is finally obtained.

[0060] Example 9

[0061] The difference from Example 1 is that benzophenone is added to the sodium tungstate solution, and the equivalent ratio of benzophenone to sodium tungstate is 1:1, and sulfonepyraclostrobin is finally obtained.

[0062] Example 10

[0063] The difference from Example 1 is that benzophenone is added to the sodium tungstate solution, and the equivalent ratio of benzophenone to sodium tungstate is 1:0.2, and finally sulfonepyraclostrobin is obtained.

[0064] Embodiment 11

[0065] The difference from Example 9 is that the photosensitizer is a combination of benzophenone and xanthenone, the molar ratio of benzophenone to xanthenone is 1:1, and sulfonepyraclostrobin is finally obtained.

[0066] Example 12

[0067] The difference from Example 9 is that the photosensitizer is a combination of benzophenone and xanthenone, the molar ratio of benzophenone to xanthenone is 1:0.1, and sulfonepyraclostrobin is finally obtained.

[0068] Embodiment 13

[0069] The difference from Example 1 is that a mixture of sodium tungstate and tungstic acid is used to replace sodium tungstate, and the molar ratio of sodium tungstate to tungstic acid in the mixture is 1:1, and sulfonepyraclostrobin is finally obtained.

[0070] Embodiment 14

[0071] The difference from Example 1 is that a mixture of sodium tungstate and tungstic acid is used to replace sodium tungstate, and the molar ratio of sodium tungstate to tungstic acid in the mixture is 1:0.5, and finally sulfonepyraclostrobin is obtained.

[0072] Embodiment 15

[0073] The difference from Example 1 is that the molar ratio of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide and catalyst is 1:2:0.1, the concentration of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole solution is 0.41 mol / L, the concentration of sodium tungstate solution is 0.68 mol / L, the reaction temperature is 30°C, the reaction residence time is 10 min, and sulfonepyrazol is finally obtained.

[0074] Example 16

[0075] The difference from Example 1 is that the molar ratio of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide and catalyst is 1:4:0.03, the concentration of 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole solution is 0.67 mol / L, the concentration of sodium tungstate solution is 1.36 mol / L, the reaction temperature is 60°C, the reaction residence time is 1 min, and sulfonepyraclostrobin is finally obtained.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that the light source in the continuous photochemical reactor 5 is removed, and sulfonepyraclostrobin is finally obtained.

[0078] The yield and purity of sulfonepyraclostrobin prepared in the above examples and comparative examples are shown in Table 1.

[0079] Table 1

[0080]

[0081] Figure 2 The gas chromatogram of sulfonepyraclostrobin in Example 1 shows that the peak of sulfonepyraclostrobin is at a retention time of 16.225 min. Figure 2 It can be seen that sulfonepyraclostrobin has a higher purity.

[0082] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0083] By introducing raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, catalyst and organic solvent into a continuous photochemical reactor for oxidation reaction, on the one hand, the introduction of light helps to shorten the oxidation reaction time from the original hour level to the minute level, and the reaction time is greatly shortened, thereby helping to improve the production efficiency of sulfonepyraclostrobin; on the other hand, the use of a continuous reactor helps to accurately control the temperature of the oxidation reaction, essentially reducing the danger of materials and reactions, and effectively solving the problem of large heat release and high process risk in batch reactions. The use of tungsten-containing compounds as catalysts helps to improve the selectivity of the oxidation reaction, thereby helping to improve the yield of sulfonepyraclostrobin.

[0084] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous synthesis method of sulfonepyraclostrobin, characterized in that: The continuous synthesis method comprises: introducing raw materials including 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, hydrogen peroxide, a catalyst and an organic solvent into a continuous photochemical reactor for continuous oxidation reaction to obtain a reaction solution; quenching and purifying the reaction solution in sequence to obtain the sulfonepyraclostrobin; the catalyst is selected from any one or more of sodium tungstate, tungstic acid and tungsten oxide; the reaction temperature in the continuous photochemical reactor is 30-60°C, and the reaction residence time in the continuous photochemical reactor is 1-10 minutes.

2. The continuous synthesis method according to claim 1, characterized in that A light source is provided in the continuous photochemical reactor, and the raw materials are processed under the irradiation of the light source, and the illumination intensity of the light source is 30mw / cm²~300mw / cm²; and / or the wavelength of the light source is a single wavelength, and the wavelength is 275~590nm.

3. The continuous synthesis method according to claim 2, characterized in that: The wavelength is 335-480 nm; and / or the light source is selected from any one or more of LED, mercury lamp, xenon lamp, laser lamp and fluorescent lamp.

4. The continuous synthesis method according to any one of claims 1 to 3, characterized in that: The molar ratio of the 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, the hydrogen peroxide and the catalyst is 1:2~4:0.03~0.

1.

5. The continuous synthesis method according to any one of claims 1 to 3, characterized in that: The raw material also includes a photosensitizer, and the equivalent ratio of the photosensitizer to the catalyst is 1:0.2-1.

6. The continuous synthesis method according to claim 5, characterized in that: The photosensitizer is selected from any one or more of benzophenone, xanthanone, acridinium salt and 1,2,3,5-tetrakis(carbazole-9-yl)-4,6-dicyanobenzene.

7. The continuous synthesis method according to claim 6, characterized in that: The photosensitizer is a combination of benzophenone and xanthenone, and the molar ratio of the benzophenone to the xanthenone is 1:0.1-1; and / or the catalyst is a combination of sodium tungstate and tungstic acid, and the molar ratio of the sodium tungstate to the tungstic acid is 1:0.5-1.

8. The continuous synthesis method according to any one of claims 1 to 3, characterized in that: The organic solvent is selected from any one or more of tetrahydrofuran, acetonitrile, dichloromethane, dichloroethane and chloroform.

9. The continuous synthesis method according to any one of claims 1 to 3, characterized in that: The continuous photochemical reactor further comprises a reactor, and the reactor is a tubular reactor.

Images