A catalytic synthesis process for indoxacarb intermediate

Abstract

The invention discloses a catalytic synthesis process for an indoxacarb intermediate, belonging to the technical field of organic synthesis. The process comprises the following steps: co-precipitating silica on the surface of microspheres assembled by a hydrothermal reaction of sucrose, reacting surface hydroxyls with amino groups in chitosan to obtain chitosan / carbon silicon microspheres, and then allowing the surface hydroxyls to undergo an esterification reaction with the phosphate groups of cyclohexanehexol hexaphosphate. The silica template is removed, and the obtained hollow carbon phosphide microspheres are used as carriers to load MOF-Pd. The catalyst is carbonized to obtain a palladium phosphide carbon-based catalyst. The palladium phosphide carbon-based catalyst has extremely high specific surface area, porous and macroporous properties, and can significantly reduce diffusion resistance in the catalytic synthesis process of the indoxacarb intermediate, prevent the influence of mass transfer limitation on catalytic efficiency, retain high adsorption, and ensure rapid mass transfer, thereby improving the catalytic efficiency of the catalyst. The indoxacarb intermediate prepared by the synthesis process has the characteristics of high product conversion rate, high raw material utilization rate and low by-products.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a catalytic synthesis process of an indoxacarb intermediate. Background Art

[0002] Indoxacarb is a new and highly effective insecticide. Its mechanism of action is as a sodium channel inhibitor, primarily blocking sodium channels in the pest's nerve cells, leading to coordinated paralysis and ultimately death of the target pest. This insecticide has a broad spectrum of activity and rapid effectiveness, demonstrating excellent efficacy against resistant pests such as the beet armyworm, diamondback moth, and cotton bollworm. Furthermore, it is non-teratogenic, non-carcinogenic, and non-mutagenic, and is highly safe for birds, aquatic organisms, and non-target organisms. Due to its relatively safe handling and environmentally friendly nature, indoxacarb has displaced some of the market share of carbamate and organophosphate products and has become a hot topic of research.

[0003] There are many synthetic routes and methods for indoxacarb. Taking the catalytic hydrogenation of the indoxacarb intermediate 2-(benzyl)-7-chloroindeno[1,2-e][1,3,4]oxadiazine-2,4a(3H,5H)-dicarboxylic acid 4a methyl ester (YCW-5) as an example, the intermediate 7-chloro-2,5-dihydroindeno[1,2-e][1,3,4]oxadiazine-4a(3H)-carboxylic acid methyl ester (YCW-6) was prepared. In this reaction, debenzyloxycarbonylation is the key step. The catalyst used is mainly 10% palladium on carbon. Dechlorination reaction occurs simultaneously with deoxycarbonylation.

[0004] To overcome dechlorination during the reaction, Chinese patent application CN104230838A discloses a method for preparing a high-purity key intermediate of the agricultural insecticide indoxacarb. The dehalogenation inhibitor morpholine is added during the hydrogenation of the indoxacarb intermediate, effectively reducing the production of dechlorination byproducts. However, most dehalogenation inhibitors are organic compounds that are difficult to remove during the subsequent indoxacarb preparation process, affecting product quality. Furthermore, dehalogenation inhibitors reduce catalyst activity and prolong reaction time.

[0005] Chinese patent publication number CN110694643B discloses a palladium catalyst and preparation method for the synthesis of an indoxacarb intermediate. The catalyst uses a mixture of activated carbon and carbon nanotubes as a carrier, effectively utilizing the unique structural characteristics of carbon nanotubes, with their high specific surface area and surface energy, which facilitate the adsorption of solid particles or small molecules. However, the lack of micropores in this solution leads to a decrease in adsorption capacity, at the expense of the porous adsorption properties of the catalyst. While this reduces diffusion resistance, it also reduces the catalytic efficiency. Summary of the Invention

[0006] The object of the present invention is to provide a catalytic synthesis process for an indoxacarb intermediate. By adding a palladium phosphide carbon-based catalyst with high catalytic effect into the synthesis process, the catalyst has high catalytic effect, extremely high specific surface area, porous and macroporous properties, and the macroporous structure can significantly reduce diffusion resistance and prevent the influence of mass transfer limitation on catalytic efficiency. It retains high adsorption and ensures rapid mass transfer, thereby improving the catalytic efficiency of the catalyst. The indoxacarb intermediate prepared by the synthesis process has the characteristics of high product conversion rate, high raw material utilization rate and low by-products.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A catalytic synthesis process for an indoxacarb intermediate comprises the following steps:

[0009] Step 1: Co-precipitate silica on the surface of the microspherical polymer assembled by the hydrothermal reaction of sucrose to obtain carbon silicon microspheres, and use the hydroxyl groups on the surface of the carbon silicon microspheres and the amino groups in chitosan to undergo hydroxylation reaction to obtain chitosan / carbon silicon microspheres with a chitosan layer coated on the surface.

[0010] Step 2: The hydroxyl groups on the surface of the chitosan / silicon carbon microspheres are esterified with the phosphate groups of cyclohexanehexol hexaphosphate, and then pyrolyzed in a muffle furnace. The silicon dioxide is washed away with hydrofluoric acid to obtain hollow carbon phosphide microspheres.

[0011] Step 3: Use hollow carbon phosphide microspheres as a carrier to load MOF-Pd, and obtain palladium phosphide carbon-based catalyst after MOF carbonization.

[0012] Furthermore, the specific preparation steps of carbon silicon microspheres in step 1 are as follows:

[0013] Add 30-35wt% sucrose solution to a polytetrafluoroethylene-lined stainless steel reactor, stir at 20-25°C and 500-600r / min for 10-12min, heat to 180-200°C, continue stirring for 3-4h, then add tetraethyl orthosilicate, anhydrous ethanol and 20-30wt% ammonia water, continue stirring and react for 8-10h, filter, wash, vacuum dry, transfer to a muffle furnace, and calcine at 750-800°C under argon atmosphere for 12-14h to obtain carbon silicon microspheres.

[0014] Furthermore, the usage ratio of sucrose solution, tetraethyl orthosilicate, anhydrous ethanol and ammonia water is 500-600 mL: 150-200 mL: 200-250 mL: 400-500 mL.

[0015] Furthermore, the specific preparation steps of chitosan / carbon silicon microspheres in step 2 are as follows:

[0016] Chitosan, 20-30 wt% hydrochloric acid solution, cetyltrimethylammonium bromide and 20-25 wt% ethanol solution were added into a reactor, stirred at 20-25°C and 500-600 r / min for 20-30 min, then carbon silicon microspheres were added, and stirring was continued for 5-6 h. The mixture was filtered, washed and vacuum dried to obtain chitosan / carbon silicon microspheres.

[0017] Furthermore, the usage ratio of chitosan, hydrochloric acid solution, hexadecyltrimethylammonium bromide, ethanol solution and carbon silicon microspheres is 400-500 g: 4-5 L: 180-200 mL: 3-4 L: 300-350 g.

[0018] Furthermore, the specific preparation steps of the hollow carbon phosphide microspheres in step 2 are as follows:

[0019] Chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate and N,N-dimethylformamide are added to a reactor, heated to 90-100°C and stirred for 2-3 hours, naturally cooled, filtered, washed, and vacuum dried to obtain carbon phosphide silicon microspheres; the carbon phosphide silicon microspheres are transferred to a muffle furnace, heated to 350-370°C and calcined for 2-3 hours under an argon atmosphere, heated to 900-950°C at a rate of 5-6°C / min, and kept warm for 2-3 hours. The product is washed with 5wt% hydrofluoric acid solution and deionized water to obtain hollow carbon phosphide microspheres.

[0020] Furthermore, the usage ratio of chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate and N,N-dimethylformamide is 250-260 g: 300-400 mL: 1-2 L.

[0021] Furthermore, the specific preparation steps of the indoxacarb intermediate are as follows:

[0022] YCW-5, anhydrous sodium acetate, palladium phosphide carbon-based catalyst and methyl acetate are added to a reaction kettle, and hydrogen is introduced at a rate of 10-20 mL / min at 10-15° C. for 1-2 minutes to replace the gas. The gas is discharged, and hydrogen replacement is performed 2-3 times at the same rate. The reaction is continued for 6-7 hours to obtain an indoxacarb intermediate, thereby completing the catalytic synthesis process.

[0023] Furthermore, the usage ratio of YCW-5, anhydrous sodium acetate, palladium phosphide carbon-based catalyst and methyl acetate is 500-520 g: 500-600 g: 20-30 g: 5-6 L.

[0024] Furthermore, the specific preparation steps of the palladium phosphide carbon-based catalyst are as follows:

[0025] Hollow carbon phosphide microspheres, 2,5-diaminoterephthalic acid and deionized water are added to a reactor, stirred at 70-80°C and 400-500r / min for 20-30min, then palladium nitrate is added, and the stirring reaction is continued for 4-6h. The product is filtered, washed, and vacuum dried. The product is transferred to a muffle furnace and calcined at 750-800°C for 4-5h under an argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0026] Furthermore, the usage ratio of the hollow carbon phosphide microspheres, 2,5-diaminoterephthalic acid, deionized water and palladium nitrate is 300-320 g: 200-300 g: 3-4 L: 300-400 g.

[0027] Beneficial effects of the present invention:

[0028] 1. The indoxacarb intermediate prepared by the present invention has the characteristics of high product conversion rate, high raw material utilization rate and low by-products by adding a palladium phosphide carbon-based catalyst with high catalytic effect in the synthesis process.

[0029] 2. The palladium phosphide carbon-based catalyst of the present invention has a highly efficient catalytic effect, and has extremely high specific surface area, porous and macroporous properties. The macroporous structure can significantly reduce the diffusion resistance, prevent the influence of mass transfer limitation on the catalytic efficiency, retain high adsorption, and ensure rapid mass transfer, thereby increasing the catalytic efficiency of the catalyst; sucrose is self-assembled into microspherical polymers in the aqueous phase through hydrophobic interaction, and silicon dioxide is deposited on the surface of the microspheres by coprecipitation to obtain carbon silicon microspheres, and the amino group in the chitosan molecular formula is combined with carbon silicon to form a microsphere. The hydroxyl groups on the surface of the microspheres combine to obtain chitosan / carbon silicon microspheres covered with a chitosan layer. The hydroxyl groups on the surface of the chitosan layer combine with the phosphate groups to obtain carbon phosphide silicon microspheres. The silicon dioxide is removed by washing with a hydrofluoric acid solution to obtain hollow carbon phosphide silicon microspheres. The remaining carboxyl groups on the surface of the hollow carbon phosphide microspheres combine with the amino groups of 2,5-diaminoterephthalic acid to achieve the in situ generation of MOF-Pd. After carbonization of MOF, a graphitized carbon layer is formed to wrap the palladium particles, thereby achieving the dispersion and fixation of palladium.

[0030] 3. In the hollow carbon phosphide silicon microspheres of the present invention, during the carbonization process of the chitosan / carbon silicon microspheres, the chitosan layer on the surface will form a carbon layer, further increasing the strength of the carbon microspheres and avoiding stress concentration caused by hydrofluoric acid etching of silicon dioxide, which may cause structural collapse. The chitosan structure contains nitrogen, and after calcination, nitrogen-doped hollow carbon phosphide microspheres can be formed. Nitrogen has a high charge and spin density. Introducing nitrogen into the catalyst can increase metal dispersion and improve catalytic activity. The electron-donating ability of nitrogen further stabilizes the palladium metal particles.

[0031] 4. The chitosan / carbon silicon microspheres of the present invention are combined with the carboxylic acid groups released after ring opening through the phosphate groups of cyclohexane hexaphosphate. The electronegativity of phosphorus is higher than that of palladium. When phosphorus is embedded in the palladium lattice, it attracts the electrons of palladium, resulting in a decrease in the d-band electron density of palladium. After the d-band center moves downward, electrons are transferred from C atoms to P atoms via P atoms, forming a stable Pd 15 P2 species and electron-rich Pd form effective electron-rich hydrogen on the hydrogen adsorption active site, effectively inhibiting C-Cl hydrogenation and reducing dehalogenation side reactions. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1: A catalytic synthesis process for an indoxacarb intermediate, comprising the following steps:

[0034] S1: Add 500 mL of 30% sucrose solution into a polytetrafluoroethylene-lined stainless steel reactor, stir at 20°C and 500 r / min for 10 min, heat to 180°C, continue stirring for 3 h, then add 150 mL of tetraethyl orthosilicate, 200 mL of anhydrous ethanol and 400 mL of 20% ammonia water, continue stirring and react for 8 h, filter, wash the filter cake with deionized water and anhydrous ethanol twice respectively, vacuum dry at 60°C for 1 h, transfer to a muffle furnace, and calcine at 750°C for 12 h under argon atmosphere to obtain carbon silicon microspheres.

[0035] Sucrose is hydrothermally decomposed and assembled into microspherical polymers, and silicon dioxide is deposited on the surface of the microspheres by co-precipitation to obtain carbon silicon microspheres.

[0036] S2: Add 400 g of chitosan, 4 L of 20% hydrochloric acid solution, 180 mL of hexadecyltrimethylammonium bromide and 3 L of 20% ethanol solution into the reactor, stir at 20 ° C and 500 r / min for 20 min, then add 300 g of carbon silicon microspheres, continue stirring for 5 h, filter, wash the filter cake with deionized water and anhydrous ethanol twice, respectively, and vacuum dry at 60 ° C for 1 h to obtain chitosan / carbon silicon microspheres.

[0037] Chitosan is dissolved in a hydrochloric acid solution, and the amino groups in the chitosan molecular formula react with the hydroxyl groups on the surface of the carbon silicon microspheres to produce a hydroxylation reaction, thereby obtaining chitosan / carbon silicon microspheres with a chitosan layer covering the surface.

[0038] S3: Add 250g chitosan / carbon silicon microspheres, 300mL cyclohexanehexol hexaphosphate and 1L N,N-dimethylformamide into the reactor, heat to 90℃ and continue stirring for 2h, cool naturally, filter, wash the filter cake with deionized water and anhydrous ethanol twice, respectively, and vacuum dry at 60℃ for 1h to obtain carbon phosphide silicon microspheres; transfer the carbon phosphide silicon microspheres to a muffle furnace, heat to 350℃ and calcine for 2h under argon atmosphere, heat to 900℃ at a rate of 5℃ / min, keep warm for 2h, wash the product with 5% hydrofluoric acid solution and deionized water twice, respectively, to obtain hollow carbon phosphide microspheres.

[0039] The hydroxyl groups on the surface of the chitosan / silicon carbon microspheres undergo an esterification reaction with the phosphate groups of cyclohexanehexol hexaphosphate to obtain phosphinated carbon silicon microspheres. The microspheres are then washed with a hydrofluoric acid solution. The hydrofluoric acid reacts with the silicon dioxide to form fluorosilicic acid, which is easily soluble in water, thereby removing the silicon dioxide.

[0040] During the carbonization process, the chitosan layer on the surface of the chitosan / carbon silicon microspheres will form a carbon layer, which further increases the strength of the carbon microspheres and avoids the stress concentration caused by the etching of silicon dioxide by hydrofluoric acid, thereby causing structural collapse. The chitosan structure contains the element N, and after calcination, it can form nitrogen-doped hollow carbon phosphide microspheres. Nitrogen has a high charge and spin density. Introducing nitrogen into the catalyst can increase the metal dispersion and improve the catalytic activity. The electron donating ability of nitrogen further stabilizes the palladium metal particles, and the phosphorus and nitrogen synergistically further reduce the dehalogenation side reaction.

[0041] S4: Add 300g of hollow carbon phosphide microspheres, 200g of 2,5-diaminoterephthalic acid and 3L of deionized water into the reactor, stir at 70℃ and 400r / min for 20min, then add 300g of palladium nitrate, continue stirring and react for 4h, filter, wash the filter cake with deionized water and anhydrous ethanol twice respectively, dry in vacuum at 60℃ for 1h, transfer the product to a muffle furnace, and calcine at 750℃ for 4h under argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0042] MOF-Pd is generated on the surface using hollow carbon phosphide microspheres as carriers. After carbonization, MOF forms a graphitized carbon layer that wraps the palladium particles, inhibiting high-temperature agglomeration, thereby achieving the dispersion and fixation of palladium.

[0043] S5: 500 g of YCW-5, 500 g of anhydrous sodium acetate, 20 g of palladium phosphide carbon-based catalyst, and 5 L of methyl acetate were added to a reactor. Hydrogen was introduced at a rate of 10 mL / min for 1 min at 10°C, the gas was exhausted, and hydrogen was replaced twice at the same rate. The reaction was continued for 6 h to obtain an indoxacarb intermediate, completing the catalytic synthesis process.

[0044] Example 2: A catalytic synthesis process for an indoxacarb intermediate, comprising the following steps:

[0045] S1: Add 550 mL of 33% sucrose solution into a polytetrafluoroethylene-lined stainless steel reactor, stir at 22.5°C and 550 r / min for 11 minutes, heat to 190°C, continue stirring for 3.5 hours, then add 175 mL of tetraethyl orthosilicate, 225 mL of anhydrous ethanol and 450 mL of 25% ammonia water, continue stirring and react for 9 hours, filter, wash the filter cake with deionized water and anhydrous ethanol twice, respectively, vacuum dry at 70°C for 1.5 hours, transfer to a muffle furnace, and calcine at 775°C for 13 hours under argon atmosphere to obtain carbon silicon microspheres.

[0046] S2: Add 450g of chitosan, 4.5L of 25% hydrochloric acid solution, 190mL of hexadecyltrimethylammonium bromide and 3.4L of 23% ethanol solution into the reactor, stir at 23°C and 550r / min for 25min, then add 330g of carbon silicon microspheres, continue stirring for 5.6h, filter, wash the filter cake with deionized water and anhydrous ethanol twice respectively, and dry in vacuum at 70°C for 1.2h to obtain chitosan / carbon silicon microspheres.

[0047] S3: Add 255g chitosan / carbon silicon microspheres, 350mL cyclohexanehexol hexaphosphate and 1.5L N,N-dimethylformamide into the reactor, heat to 95℃ and continue stirring for 2.5h, cool naturally, filter, wash the filter cake with deionized water and anhydrous ethanol twice, respectively, and vacuum dry at 70℃ for 1.5h to obtain carbon phosphide silicon microspheres; transfer the carbon phosphide silicon microspheres to a muffle furnace, heat to 360℃ under argon atmosphere and calcine for 2.5h, heat to 925℃ at a rate of 5.5℃ / min, keep warm for 2.5h, wash the product with 5% hydrofluoric acid solution and deionized water 2.5 times, respectively, to obtain hollow carbon phosphide microspheres.

[0048] S4: 310 g of hollow carbon phosphide microspheres, 250 g of 2,5-diaminoterephthalic acid and 3.5 L of deionized water were added to the reactor, stirred at 75 ° C and 450 r / min for 25 min, and then 350 g of palladium nitrate was added. The stirring reaction was continued for 5 h, filtered, and the filter cake was washed twice with deionized water and anhydrous ethanol respectively, and vacuum dried at 70 ° C for 1.5 h. The product was transferred to a muffle furnace and calcined at 780 ° C for 4.5 h under argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0049] S5: 510 g of YCW-5, 550 g of anhydrous sodium acetate, 25 g of palladium phosphide carbon-based catalyst, and 5.5 L of methyl acetate were added to a reactor. Hydrogen was introduced at a rate of 15 mL / min for 1.5 min at 12.5° C., the gas was exhausted, and hydrogen was replaced twice at the same rate. The reaction was continued for 6.5 h to obtain an indoxacarb intermediate, completing the catalytic synthesis process.

[0050] Example 3: A catalytic synthesis process for an indoxacarb intermediate, comprising the following steps:

[0051] S1: Add 600 mL of 35% sucrose solution into a polytetrafluoroethylene-lined stainless steel reactor, stir at 25°C and 600 r / min for 12 minutes, heat to 200°C, and continue stirring for 4 hours. Then add 200 mL of tetraethyl orthosilicate, 250 mL of anhydrous ethanol and 500 mL of 30% ammonia water, continue stirring and react for 10 hours, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, dry it in vacuum at 80°C for 2 hours, transfer it to a muffle furnace, and calcine it at 800°C for 14 hours under argon atmosphere to obtain carbon silicon microspheres.

[0052] S2: Add 500 g of chitosan, 5 L of 30% hydrochloric acid solution, 200 mL of cetyltrimethylammonium bromide and 4 L of 25% ethanol solution into the reactor, stir at 25 ° C and 600 r / min for 30 min, then add 350 g of carbon silicon microspheres, continue stirring for 6 h, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, and dry it in vacuum at 80 ° C for 2 h to obtain chitosan / carbon silicon microspheres.

[0053] S3: Add 260g chitosan / carbon silicon microspheres, 400mL cyclohexanehexol hexaphosphate and 2L N,N-dimethylformamide into the reactor, heat to 100℃ and continue stirring for 3h, cool naturally, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, and vacuum dry at 80℃ for 2h to obtain carbon phosphide silicon microspheres; transfer the carbon phosphide silicon microspheres to a muffle furnace, heat to 370℃ and calcine for 3h under argon atmosphere, heat to 950℃ at a rate of 6℃ / min, keep warm for 3h, wash the product with 5% hydrofluoric acid solution and deionized water three times respectively to obtain hollow carbon phosphide microspheres.

[0054] S4: Add 320g of hollow carbon phosphide microspheres, 300g of 2,5-diaminoterephthalic acid and 4L of deionized water into the reactor, stir at 80℃ and 500r / min for 30min, then add 400g of palladium nitrate, continue stirring and react for 6h, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, dry it in vacuum at 80℃ for 2h, transfer the product to a muffle furnace, and calcine at 800℃ for 5h under argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0055] S5: 520 g of YCW-5, 600 g of anhydrous sodium acetate, 30 g of palladium phosphide carbon-based catalyst, and 6 L of methyl acetate were added to a reactor. Hydrogen was introduced at a rate of 20 mL / min for 2 minutes at 15°C, and the gas was exhausted. The hydrogen was replaced three times at the same rate, and the reaction was continued for 7 hours to obtain an indoxacarb intermediate, completing the catalytic synthesis process.

[0056] Comparative Example 1: Based on Example 3, the phosphated carbon silicon microspheres in step S3 were replaced with chitosan / carbon silicon microspheres of equal mass in step S2, and the remaining steps remained unchanged to prepare an indoxacarb intermediate.

[0057] Comparative Example 2: Based on Example 3, without the treatment in step S2, the carbon silicon microspheres in step S1 were directly used as chitosan / carbon silicon microspheres in step S3, and the other steps remained unchanged to prepare an indoxacarb intermediate.

[0058] Comparative Example 3: Based on Example 3, 2,5-diaminoterephthalic acid in step S3 was omitted, and the remaining steps remained unchanged to prepare an indoxacarb intermediate.

[0059] The indoxacarb intermediates prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were filtered to remove the catalyst, and the reaction liquid was taken out and analyzed by liquid chromatography. The results are shown in Table 1:

[0060] Table 1 Liquid chromatography analysis of indoxacarb intermediates

[0061]

[0062] As can be seen from Table 1, the palladium phosphide carbon-based catalysts prepared in Examples 1 to 3 catalyze the synthesis of indoxacarb intermediates. The conversion rate of YCW-5 is high and the yield of YCW-6 is significantly higher than that of the comparative example, and the dechlorinated impurities are significantly lower than those of the comparative example. This shows that the palladium phosphide carbon-based catalyst prepared by the present invention catalyzes the synthesis of indoxacarb intermediates and has the characteristics of high product conversion rate, high raw material utilization rate and few by-products.

[0063] In Comparative Example 1, the phosphide carbon silicon microspheres are replaced with chitosan / carbon silicon microspheres. The phosphate groups of cyclohexane hexaphosphate are combined with the hydroxyl groups of chitosan / carbon silicon microspheres. The electronegativity of phosphorus is higher than that of palladium. When phosphorus is embedded in the palladium lattice, it attracts the electrons of palladium, resulting in a decrease in the d-band electron density of palladium. After the d-band center moves downward, the electrons are transferred from the C atom to the P atom via the P atom, forming a stable Pd 15 P2 species and Pd in an electron-rich state form effective electron-rich hydrogen on the hydrogen adsorption active site, effectively achieving the inhibition of C-Cl hydrogenation and reducing the dehalogenation side reaction. After losing the phosphorus modification, the dehalogenation side reaction is significantly increased.

[0064] In Comparative Example 2, carbon silicon microspheres are directly used as chitosan / carbon silicon microspheres. During the carbonization process, the chitosan layer on the surface of the chitosan / carbon silicon microspheres will form a carbon layer, which further increases the strength of the carbon microspheres and avoids the stress concentration caused by HF etching of silicon dioxide, thereby causing structural collapse. The chitosan structure contains N element, and nitrogen-doped hollow carbon phosphide microspheres can be formed after calcination. Nitrogen has a high charge and spin density. Introducing nitrogen into the carbonyl catalyst can increase the metal dispersion and improve the catalytic activity. The electron donating ability of nitrogen further stabilizes the palladium metal particles. After losing the chitosan layer, the ability to inhibit the dehalogenation side reaction decreases.

[0065] In Comparative Example 3, 2,5-diaminoterephthalic acid was discarded, and MOF-Pd was generated on the surface by using hollow carbon phosphide microspheres as a carrier. After carbonization, MOF formed a graphitized carbon layer to wrap the palladium particles, inhibiting high-temperature agglomeration, thereby achieving the dispersion and fixation of palladium. Without 2,5-diaminoterephthalic acid, MOF-Pd could not be generated, and thus the palladium could not be effectively fixed.

[0066] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0067] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A catalytic synthesis process for an indoxacarb intermediate, comprising: YCW-5 is subjected to a hydrogenation reaction under alkaline conditions with methyl acetate as solvent and catalyzed by a palladium phosphide carbon-based catalyst to obtain an indoxacarb intermediate, wherein the palladium phosphide carbon-based catalyst is prepared by the following steps: Step 1: Co-precipitating silica on the surface of a microspherical polymer assembled by a hydrothermal reaction of sucrose to obtain carbon silicon microspheres, and then using the hydroxyl groups on the surface of the carbon silicon microspheres to react with the amino groups in chitosan to produce chitosan / carbon silicon microspheres coated with a chitosan layer; Step 2: esterifying the hydroxyl groups on the surface of the chitosan / silicon carbon microspheres with the phosphate groups of cyclohexanehexol hexaphosphate, pyrolyzing the microspheres in a muffle furnace, and washing with hydrofluoric acid to remove silica to obtain hollow carbon phosphide microspheres; Step 3: Use hollow carbon phosphide microspheres as a carrier to load MOF-Pd, and obtain palladium phosphide carbon-based catalyst after MOF carbonization.

2. The catalytic synthesis process of an indoxacarb intermediate according to claim 1, characterized in that: The specific preparation steps of the carbon silicon microspheres in step 1 are as follows: Add 30-35wt% sucrose solution to a polytetrafluoroethylene-lined stainless steel reactor, stir at 20-25°C and 500-600r / min for 10-12min, heat to 180-200°C and continue stirring for 3-4h, then add tetraethyl orthosilicate, anhydrous ethanol and 20-30wt% ammonia water, continue stirring and react for 8-10h, filter, wash, vacuum dry, transfer to a muffle furnace, and calcine at 750-800°C under argon atmosphere for 12-14h to obtain carbon silicon microspheres.

3. The catalytic synthesis process of an indoxacarb intermediate according to claim 2, characterized in that: The usage ratio of the sucrose solution, tetraethyl orthosilicate, anhydrous ethanol and ammonia water is 500-600 mL: 150-200 mL: 200-250 mL: 400-500 mL.

4. The catalytic synthesis process of an indoxacarb intermediate according to claim 1, characterized in that: The specific preparation steps of the chitosan / carbon silicon microspheres in step 2 are as follows: Chitosan, 20-30 wt% hydrochloric acid solution, cetyltrimethylammonium bromide and 20-25 wt% ethanol solution were added into a reactor, stirred at 20-25°C and 500-600 r / min for 20-30 min, then carbon silicon microspheres were added, and stirring was continued for 5-6 h. The mixture was filtered, washed and vacuum dried to obtain chitosan / carbon silicon microspheres.

5. The catalytic synthesis process of an indoxacarb intermediate according to claim 4, characterized in that: The usage ratio of the chitosan, hydrochloric acid solution, hexadecyltrimethylammonium bromide, ethanol solution and carbon silicon microspheres is 400-500 g: 4-5 L: 180-200 mL: 3-4 L: 300-350 g.

6. The catalytic synthesis process of an indoxacarb intermediate according to claim 1, characterized in that: The specific preparation steps of the hollow carbon phosphide microspheres in step 2 are as follows: Chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate and N,N-dimethylformamide are added to a reactor, heated to 90-100°C and stirred for 2-3 hours, naturally cooled, filtered, washed, and vacuum dried to obtain carbon phosphide silicon microspheres; the carbon phosphide silicon microspheres are transferred to a muffle furnace, heated to 350-370°C and calcined for 2-3 hours under an argon atmosphere, heated to 900-950°C at a rate of 5-6°C / min, and kept warm for 2-3 hours. The product is washed with 5wt% hydrofluoric acid solution and deionized water to obtain hollow carbon phosphide microspheres.

7. The catalytic synthesis process of an indoxacarb intermediate according to claim 6, characterized in that: The usage ratio of the chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate and N,N-dimethylformamide is 250-260 g: 300-400 mL: 1-2 L.

8. The catalytic synthesis process of an indoxacarb intermediate according to claim 1, characterized in that: The specific preparation steps of the palladium phosphide carbon-based catalyst in step 3 are as follows: Hollow carbon phosphide microspheres, 2,5-diaminoterephthalic acid and deionized water are added to a reactor, stirred at 70-80°C and 400-500r / min for 20-30min, then palladium nitrate is added, and the stirring reaction is continued for 4-6h. The product is filtered, washed, and vacuum dried. The product is transferred to a muffle furnace and calcined at 750-800°C for 4-5h under an argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

9. The catalytic synthesis process of an indoxacarb intermediate according to claim 8, characterized in that: The usage ratio of the hollow carbon phosphide microspheres, 2,5-diaminoterephthalic acid, deionized water and palladium nitrate is 300-320 g: 200-300 g: 3-4 L: 300-400 g.

10. The catalytic synthesis process of an indoxacarb intermediate according to claim 1, characterized in that: The specific preparation steps of the indoxacarb intermediate are as follows: YCW-5, anhydrous sodium acetate, palladium phosphide carbon-based catalyst and methyl acetate are added to a reaction kettle, and hydrogen is introduced at a rate of 10-20 mL / min at 10-15° C. for 1-2 minutes to replace the gas, and the gas is exhausted. The hydrogen replacement is performed 2-3 times at the same rate, and the reaction is continued for 6-7 hours to obtain an indoxacarb intermediate, thereby completing the catalytic synthesis process; Furthermore, the usage ratio of YCW-5, anhydrous sodium acetate, palladium phosphide carbon-based catalyst and methyl acetate is 500-520 g: 500-600 g: 20-30 g: 5-6 L.

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