Catalytic synthesis process of indoxacarb intermediate

Abstract

The invention discloses a catalytic synthesis process of an indoxacarb intermediate, and belongs to the technical field of organic synthesis.The catalytic synthesis process comprises the steps that silicon dioxide is coprecipitated on the surfaces of microspheres assembled through a hydrothermal reaction of sucrose, hydroxyl on the surfaces reacts with amino in chitosan, and chitosan / carbon silicon microspheres are obtained; then carrying out esterification reaction on hydroxyl groups on the surface and phosphoric acid groups of inositol hexaphosphate, removing the silicon dioxide template to obtain hollow carbon phosphide microspheres as carriers to load MOF-Pd, and carbonizing to obtain a palladium phosphide carbon-based catalyst; the palladium phosphide carbon-based catalyst has extremely high specific surface area and porous and macroporous properties, can significantly reduce diffusion resistance and prevent the influence of mass transfer limitation on catalytic efficiency in a process of catalyzing synthesis of an indoxacarb intermediate, not only retains high adsorbability, but also guarantees rapid mass transfer, thereby improving the catalytic efficiency of the catalyst and reducing the cost 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 few byproducts.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and specifically relates to a catalytic synthesis process for indoxacarb intermediates. Background Art

[0002] Indoxacarb is a latest highly efficient insecticide. Its mechanism of action is a sodium channel inhibitor, mainly blocking the sodium channels in the nerve cells of pests, resulting in coordinated paralysis and ultimately death of the target pests. This variety has a broad insecticidal spectrum and quick effect, and has excellent control effects on resistant pests such as Spodoptera exigua, Plutella xylostella, and Helicoverpa armigera. In addition, this pesticide has no teratogenic, carcinogenic, or mutagenic properties, and is also very safe for birds, aquatic organisms, and non-target substances. Due to the relatively safe operation of indoxacarb and its very friendly environment, it has replaced a part of the market share of carbamate and organophosphorus products and has become a current research hotspot.

[0003] There are various synthesis routes and methods for indoxacarb. Taking the catalytic hydrogenation of indoxacarb intermediate methyl 2-(benzyl)-7-chloroindeno[1,2-e][1,3,4]oxadiazine-2,4a(3H,5H)-dicarboxylate (YCW-5) as an example, the intermediate methyl 7-chloro-2,5-dihydroindeno[1,2-e][1,3,4]oxadiazine-4a(3H)-carboxylate (YCW-6) is prepared. In this reaction, the debenzoyloxycarbonylation is a key step, and the main catalyst used is 10% palladium on carbon. At the same time of deoxycarbonylation, a dechlorination reaction will occur.

[0004] In order to overcome the dechlorination in the reaction, Chinese Patent Application CN104230838A discloses a preparation method for high-purity key intermediates of agricultural insecticide indoxacarb. Morpholine, a dehalogenation inhibitor, is added during the hydrogenation of indoxacarb intermediates, effectively reducing the generation of dechlorination by-products. However, most dehalogenation inhibitors are organic compounds and are difficult to remove in the subsequent preparation process of indoxacarb, affecting the product quality. At the same time, the dehalogenation inhibitor will reduce the activity of the catalyst and prolong the reaction time.

[0005] Chinese Patent with Publication No. CN110694643B discloses a palladium catalyst for indoxacarb intermediate synthesis and its preparation method. A mixture of activated carbon and carbon nanotubes is used as the carrier, effectively utilizing the unique structural characteristics of carbon nanotubes, high specific surface area and surface energy, which is beneficial to the adsorption of solid particles or small molecules. However, the lack of micropores in this scheme will lead to a decrease in adsorption capacity, sacrificing the porous adsorption property of the catalyst. Although the diffusion resistance is reduced, the catalytic efficiency of the catalyst is also reduced. Summary of the Invention

[0006] The object of the present invention is to provide a catalytic synthesis process for indoxacarb intermediates. By adding a palladium phosphide-carbon-based catalyst with high catalytic activity in the synthesis process, it has high catalytic activity, extremely high specific surface area, porous and macroporous properties. The macroporous structure can significantly reduce the diffusion resistance and prevent the influence of mass transfer limitation on the catalytic efficiency. It not only retains high adsorption but also ensures rapid mass transfer, thereby improving the catalytic efficiency of the catalyst, making the indoxacarb intermediate prepared by this synthesis process have the characteristics of high product conversion rate, high raw material utilization rate and few by-products.

[0007] The object of the present invention can be achieved by the following technical solutions: A catalytic synthesis process for indoxacarb intermediates, comprising the following steps: Step 1: Co-precipitate silica on the surface of the microspherical polymer assembled by sucrose hydrothermal reaction to obtain carbon-silica microspheres. Use the hydroxyl groups on the surface of the carbon-silica microspheres to undergo hydroxyamination reaction with the amino groups in chitosan to obtain chitosan / carbon-silica microspheres with a chitosan layer coated on the surface.

[0008] Step 2: Esterify the hydroxyl groups on the surface of the chitosan / silicon-carbon microspheres with the phosphate groups of cyclohexanehexol hexaphosphate, and then pyrolyze in a muffle furnace. Wash away the silica with hydrofluoric acid to obtain hollow palladium phosphide-carbon microspheres.

[0009] Step 3: Load MOF-Pd using the hollow palladium phosphide-carbon microspheres as a carrier, and obtain a palladium phosphide-carbon-based catalyst after carbonization of MOF.

[0010] Furthermore, the specific preparation steps of the carbon-silica microspheres in Step 1 are as follows: Add a 30-35 wt% sucrose solution to a stainless steel reaction kettle with a polytetrafluoroethylene inner liner, stir at 20-25 °C and 500-600 r / min for 10-12 min, heat to 180-200 °C, continue stirring for 3-4 h, then add tetraethyl orthosilicate, absolute ethanol and 20-30 wt% ammonia water, continue stirring and reacting for 8-10 h, filter, wash, vacuum dry, transfer to a muffle furnace, and calcine at 750-800 °C for 12-14 h in an argon atmosphere to obtain carbon-silica microspheres.

[0011] Furthermore, the dosage ratio of the sucrose solution, tetraethyl orthosilicate, absolute ethanol and ammonia water is 500-600 mL: 150-200 mL: 200-250 mL: 400-500 mL.

[0012] Furthermore, the specific preparation steps of the chitosan / carbon-silica microspheres in Step 2 are as follows: Chitosan, 20 - 30 wt% hydrochloric acid solution, cetyltrimethylammonium bromide, and 20 - 25 wt% ethanol solution were added to a reaction kettle, stirred at 20 - 25 °C and 500 - 600 r / min for 20 - 30 min, then carbon silicon microspheres were added, and stirring continued for 5 - 6 h. After filtration, washing, and vacuum drying, chitosan / carbon silicon microspheres were obtained.

[0013] Furthermore, the dosage ratio of chitosan, hydrochloric acid solution, cetyltrimethylammonium bromide, ethanol solution, and carbon silicon microspheres was 400 - 500 g : 4 - 5 L : 180 - 200 mL : 3 - 4 L : 300 - 350 g.

[0014] Furthermore, the specific preparation steps of the hollow carbon phosphide microspheres in step two are as follows: Chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate, and N,N - dimethylformamide were added to a reaction kettle, heated to 90 - 100 °C and stirred continuously for 2 - 3 h, then naturally cooled, filtered, washed, and vacuum dried to obtain carbon phosphide silicon microspheres; the carbon phosphide silicon microspheres were transferred to a muffle furnace, calcined at 350 - 370 °C for 2 - 3 h under an argon atmosphere, heated to 900 - 950 °C at a rate of 5 - 6 °C / min, and held for 2 - 3 h. The product was washed with 5 wt% hydrofluoric acid solution and deionized water to obtain hollow carbon phosphide microspheres.

[0015] Furthermore, the dosage ratio of chitosan / carbon silicon microspheres, cyclohexanehexol hexaphosphate, and N,N - dimethylformamide was 250 - 260 g : 300 - 400 mL : 1 - 2 L.

[0016] Furthermore, the specific preparation steps of the indoxacarb intermediate are as follows: YCW - 5, anhydrous sodium acetate, palladium phosphide carbon - based catalyst, and methyl acetate were added to a reaction kettle. At 10 - 15 °C, hydrogen was introduced at a rate of 10 - 20 mL / min for 1 - 2 min for replacement, the gas was discharged, and hydrogen replacement was carried out 2 - 3 times at the same rate. The reaction continued for 6 - 7 h to obtain an indoxacarb intermediate, completing the catalytic synthesis process.

[0017] Furthermore, the dosage ratio of YCW - 5, anhydrous sodium acetate, palladium phosphide carbon - based catalyst, and methyl acetate was 500 - 520 g : 500 - 600 g : 20 - 30 g : 5 - 6 L.

[0018] Furthermore, the specific preparation steps of the palladium phosphide carbon - based catalyst are as follows: Add hollow carbon phosphide microspheres, 2,5-diaminoterephthalic acid, and deionized water into a reaction kettle, stir at 70 - 80 °C and 400 - 500 r / min for 20 - 30 min, then add palladium nitrate, continue to stir and react for 4 - 6 h, filter, wash, and dry under vacuum. Transfer the product to a muffle furnace, and calcine it at 750 - 800 °C for 4 - 5 h under an argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0019] Furthermore, the dosage 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.

[0020] Advantages of the present invention: 1. For the indoxacarb intermediate prepared by the present invention, by adding a palladium phosphide carbon-based catalyst with high catalytic efficiency in the synthesis process, the synthesis process has the characteristics of high product conversion rate, high raw material utilization rate, and few by-products.

[0021] 2. The palladium phosphide carbon-based catalyst of the present invention has high catalytic efficiency, extremely high specific surface area, porous and macroporous properties. The macroporous structure can significantly reduce the diffusion resistance and prevent the influence of mass transfer limitation on the catalytic efficiency. It not only retains high adsorption but also ensures rapid mass transfer, thereby increasing the catalytic efficiency of the catalyst. The sucrose self-assembles into microspherical polymers in the aqueous phase through hydrophobic interaction, and silica is deposited on the microsphere surface by the co-precipitation method to obtain carbon-silica microspheres. The amino group in the chitosan molecular formula combines with the hydroxyl group on the surface of the carbon-silica microspheres to obtain chitosan / carbon-silica microspheres covered with a chitosan layer. The surface of the chitosan layer is rich in hydroxyl groups that combine with phosphate groups to obtain carbon phosphide-silica microspheres. The silica is removed by washing with hydrofluoric acid solution to obtain hollow carbon phosphide-silica microspheres. The remaining carboxyl groups on the surface of the hollow carbon phosphide microspheres combine with the amino group of 2,5-diaminoterephthalic acid to realize the in-situ generation of MOF-Pd. After the MOF is carbonized, a graphitized carbon layer is formed to wrap the palladium particles, thereby realizing the dispersion and fixation of palladium.

[0022] 3. For the hollow carbon phosphide-silica microspheres of the present invention, during the carbonization process of the chitosan / carbon-silica microspheres, the chitosan layer on the surface will form a carbon layer, further increasing the strength of the carbon microspheres, avoiding stress concentration caused by the etching of silica by hydrofluoric acid and thus preventing structural collapse. The chitosan structural formula contains N element, 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 the metal dispersion and improve the catalytic activity. The electron-donating ability of nitrogen further stabilizes the palladium metal particles.

[0023] 4. The chitosan / carbon-silicon microspheres of the present invention are formed by the combination of the phosphate groups of cyclohexitol hexaphosphate with the carboxylic acid groups released after ring opening. Since the electronegativity of phosphorus is higher than that of palladium, when phosphorus is embedded in the palladium lattice, it will attract the electrons of palladium, resulting in a decrease in the electron density of the d-band of palladium and a downward shift of the d-band center. After that, electrons transfer from the C atom through the P atom to the Pd atom, forming stable Pd 15 species of P2 and Pd in a rich electron state. Effective electron-rich hydrogen is formed at the hydrogen adsorption active site, effectively achieving the inhibitory effect on C-Cl hydrogenation and reducing the dehalogenation side reaction. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0025] Example 1: A catalytic synthesis process for indoxacarb intermediate includes the following preparation steps: S1: Add 500 mL of a 30% sucrose solution by mass to a stainless steel reaction kettle with a polytetrafluoroethylene inner lining, 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 absolute ethanol, and 400 mL of a 20% ammonia water solution by mass, continue stirring and reacting for 8 h, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, dry in vacuum at 60 °C for 1 h, transfer to a muffle furnace, and calcine at 750 °C for 12 h in an argon atmosphere to obtain carbon-silicon microspheres.

[0026] The sucrose is pyrolytically assembled into a microspherical polymer by hydrothermal reaction, and silica is deposited on the surface of the microspheres by the coprecipitation method to obtain carbon-silicon microspheres.

[0027] S2: Add 400 g of chitosan, 4 L of a 20% hydrochloric acid solution by mass, 180 mL of cetyltrimethylammonium bromide, and 3 L of a 20% ethanol solution by mass to the reaction kettle, 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 twice with deionized water and absolute ethanol respectively, dry in vacuum at 60 °C for 1 h to obtain chitosan / carbon-silicon microspheres.

[0028] Chitosan is dissolved in the hydrochloric acid solution, and the amino group in the chitosan molecular formula undergoes a hydroxyamination reaction with the hydroxyl groups on the surface of the carbon-silicon microspheres to obtain chitosan / carbon-silicon microspheres with a chitosan layer covering the surface.

[0029] S3: Add 250 g of chitosan / carbon-silicon microspheres, 300 mL of cyclohexanehexol hexaphosphate, and 1 L of N,N-dimethylformamide into a reaction kettle, heat to 90 °C and continue stirring for 2 h, then cool naturally, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry in vacuum at 60 °C for 1 h to obtain phosphated carbon-silicon microspheres; transfer the phosphated carbon-silicon microspheres to a muffle furnace, under an argon atmosphere, heat to 350 °C and calcine for 2 h, then heat to 900 °C at a rate of 5 °C / min, hold for 2 h, wash the product twice with a 5% hydrofluoric acid solution and deionized water respectively to obtain hollow phosphated carbon microspheres.

[0030] The hydroxyl groups on the surface of chitosan / silicon-carbon microspheres react with the phosphate groups of cyclohexanehexol hexaphosphate to obtain phosphated carbon-silicon microspheres. By washing with a hydrofluoric acid solution, hydrofluoric acid can react with silicon dioxide to form fluosilicic acid, which is easily soluble in water, thus removing silicon dioxide.

[0031] During the carbonization process, the chitosan layer on the surface of chitosan / carbon-silicon microspheres will form a carbon layer, which further increases the strength of the carbon microspheres, avoids stress concentration caused by the etching of silicon dioxide by hydrofluoric acid and thus prevents structural collapse. The chitosan structural formula contains N element, and after calcination, it can form nitrogen-doped hollow phosphated carbon microspheres. Nitrogen element 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 element further stabilizes the palladium metal particles, and the phosphorus-nitrogen synergy further reduces the dehalogenation side reaction.

[0032] S4: Add 300 g of hollow phosphated carbon microspheres, 200 g of 2,5-diaminoterephthalic acid, and 3 L of deionized water into a reaction kettle, stir at 70 °C and 400 r / min for 20 min, then add 300 g of palladium nitrate, continue stirring and reacting for 4 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, dry in vacuum at 60 °C for 1 h, transfer the product to a muffle furnace, under an argon atmosphere, calcine at 750 °C for 4 h to obtain a palladium phosphated carbon-based catalyst.

[0033] Using hollow phosphated carbon microspheres as a carrier to realize the generation of MOF-Pd on the surface. After the MOF is carbonized, a graphitized carbon layer is formed to wrap the palladium particles, inhibiting high-temperature agglomeration, thereby realizing the dispersion and fixation of palladium.

[0034] S5: Add 500 g of YCW-5, 500 g of anhydrous sodium acetate, 20 g of palladium phosphated carbon-based catalyst, and 5 L of methyl acetate into a reaction kettle, at 10 °C, introduce hydrogen at a rate of 10 mL / min for 1 min for replacement, discharge the gas, perform hydrogen replacement twice at the same rate, and continue reacting for 6 h to obtain an indoxacarb intermediate, completing the catalytic synthesis process.

[0035] Example 2: A catalytic synthesis process of indoxacarb intermediate, which is prepared by the following steps: S1: Add 550 mL of sucrose solution with a mass fraction of 33% into a stainless-steel reactor with a polytetrafluoroethylene inner lining. Stir at 22.5 °C and 550 r / min for 11 min, heat to 190 °C, continue stirring for 3.5 h, then add 175 mL of tetraethyl orthosilicate, 225 mL of absolute ethanol, and 450 mL of ammonia water with a mass fraction of 25%. Continue stirring and reacting for 9 h, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, dry in vacuum at 70 °C for 1.5 h, transfer to a muffle furnace, and calcine at 775 °C for 13 h in an argon atmosphere to obtain carbon-silica microspheres.

[0036] S2: Add 450 g of chitosan, 4.5 L of hydrochloric acid solution with a mass fraction of 25%, 190 mL of cetyltrimethylammonium bromide, and 3.4 L of ethanol solution with a mass fraction of 23% into the reactor. Stir at 23 °C and 550 r / min for 25 min, then add 330 g of carbon-silica microspheres, continue stirring for 5.6 h, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, dry in vacuum at 70 °C for 1.2 h to obtain chitosan / carbon-silica microspheres.

[0037] S3: Add 255 g of chitosan / carbon-silica microspheres, 350 mL of cyclohexanehexol hexaphosphate, and 1.5 L of N,N-dimethylformamide into the reactor. Heat to 95 °C and continue stirring for 2.5 h, cool naturally, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, dry in vacuum at 70 °C for 1.5 h to obtain phosphated carbon-silica microspheres; transfer the phosphated carbon-silica microspheres to a muffle furnace, heat to 360 °C in an argon atmosphere and calcine for 2.5 h, heat to 925 °C at a rate of 5.5 °C / min, hold for 2.5 h, wash the product 2.5 times with hydrofluoric acid solution with a mass fraction of 5% and deionized water respectively to obtain hollow phosphated carbon microspheres.

[0038] S4: Add 310 g of hollow phosphated carbon microspheres, 250 g of 2,5-diaminoterephthalic acid, and 3.5 L of deionized water into the reactor. Stir at 75 °C and 450 r / min for 25 min, then add 350 g of palladium nitrate, continue stirring and reacting for 5 h, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, dry in vacuum at 70 °C for 1.5 h, transfer the product to a muffle furnace, and calcine at 780 °C for 4.5 h in an argon atmosphere to obtain a palladium phosphated carbon-based catalyst.

[0039] S5: Add 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 into the reaction kettle. At 12.5 °C, introduce hydrogen at a rate of 15 mL / min for 1.5 min for replacement, discharge the gas, conduct hydrogen replacement twice at the same rate, and continue the reaction for 6.5 h to obtain an indoxacarb intermediate, thus completing the catalytic synthesis process.

[0040] Example 3: A catalytic synthesis process for an indoxacarb intermediate, which includes the following preparation steps: S1: Add 600 mL of a sucrose solution with a mass fraction of 35% into a stainless steel reaction kettle with a polytetrafluoroethylene inner lining. Stir at 25 °C and 600 r / min for 12 min, heat to 200 °C, continue stirring for 4 h, then add 200 mL of tetraethyl orthosilicate, 250 mL of absolute ethanol, and 500 mL of ammonia water with a mass fraction of 30%. Continue stirring and reacting for 10 h, filter, wash the filter cake 3 times with deionized water and absolute ethanol respectively, dry it in vacuum at 80 °C for 2 h, transfer it to a muffle furnace, and calcine it at 800 °C for 14 h in an argon atmosphere to obtain carbon-silica microspheres.

[0041] S2: Add 500 g of chitosan, 5 L of hydrochloric acid solution with a mass fraction of 30%, 200 mL of cetyltrimethylammonium bromide, and 4 L of ethanol solution with a mass fraction of 25% into the reaction kettle. Stir at 25 °C and 600 r / min for 30 min, then add 350 g of carbon-silica microspheres, continue stirring for 6 h, filter, wash the filter cake 3 times with deionized water and absolute ethanol respectively, dry it in vacuum at 80 °C for 2 h to obtain chitosan / carbon-silica microspheres.

[0042] S3: Add 260 g of chitosan / carbon-silica microspheres, 400 mL of cyclohexanehexol hexaphosphate, and 2 L of N,N-dimethylformamide into the reaction kettle. Heat to 100 °C and continue stirring for 3 h, then cool naturally, filter, wash the filter cake 3 times with deionized water and absolute ethanol respectively, dry it in vacuum at 80 °C for 2 h to obtain phosphated carbon-silica microspheres; transfer the phosphated carbon-silica microspheres to a muffle furnace, heat to 370 °C in an argon atmosphere and calcine for 3 h, heat to 950 °C at a rate of 6 °C / min, hold for 3 h, wash the product 3 times with a hydrofluoric acid solution with a mass fraction of 5% and deionized water respectively to obtain hollow phosphated carbon microspheres.

[0043] S4: Add 320 g of hollow carbon phosphide microspheres, 300 g of 2,5-diaminoterephthalic acid, and 4 L of deionized water into a reaction kettle. Stir at 80 °C and 500 r / min for 30 min, then add 400 g of palladium nitrate, and continue to stir and react for 6 h. Filter, wash the filter cake with deionized water and absolute ethanol three times respectively, dry in vacuum at 80 °C for 2 h. Transfer the product to a muffle furnace, and calcine at 800 °C for 5 h under an argon atmosphere to obtain a palladium phosphide carbon-based catalyst.

[0044] S5: Add 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 into a reaction kettle. At 15 °C, introduce hydrogen at a rate of 20 mL / min for 2 min for replacement, discharge the gas, and perform three hydrogen replacements at the same rate. Continue to react for 7 h to obtain an indoxacarb intermediate, and complete the catalytic synthesis process.

[0045] Comparative Example 1: On the basis of Example 3, replace the carbon phosphide silicon microspheres in step S3 with the chitosan / carbon silicon microspheres in step S2 of the same mass, and keep the remaining steps unchanged to prepare an indoxacarb intermediate.

[0046] Comparative Example 2: On the basis of Example 3, without going through the treatment of step S2, directly use the carbon silicon microspheres in step S1 as the chitosan / carbon silicon microspheres in step S3, and keep the remaining steps unchanged to prepare an indoxacarb intermediate.

[0047] Comparative Example 3: On the basis of Example 3, discard 2,5-diaminoterephthalic acid in step S3, and keep the remaining steps unchanged to prepare an indoxacarb intermediate.

[0048] Filter to remove the catalyst from the indoxacarb intermediates prepared in Examples 1 - 3 and Comparative Examples 1 - 3, take out the reaction solution, and analyze it by liquid chromatography. The results are shown in Table 1: Table 1 Liquid Chromatography Analysis Table of Indoxacarb Intermediate

[0049] As can be seen from Table 1, for the synthesis of indoxacarb intermediate catalyzed by the palladium phosphide carbon-based catalyst prepared in Examples 1 - 3, the conversion rate of YCW-5 and the yield of YCW-6 are significantly higher than those of the comparative examples, and the dechlorination impurities are significantly lower than those of the comparative examples. This shows that the palladium phosphide carbon-based catalyst prepared by the present invention for the synthesis of indoxacarb intermediate has the characteristics of high product conversion rate, high raw material utilization rate, and few by-products.

[0050] In Comparative Example 1, the silicon carbide microspheres were replaced with chitosan / silicon carbide microspheres. The phosphate groups of cyclohexanehexol hexaphosphate were combined with the hydroxyl groups of chitosan / silicon carbide microspheres. Since the electronegativity of phosphorus is higher than that of palladium, when phosphorus is embedded in the palladium lattice, it will attract the electrons of palladium, resulting in a decrease in the d-band electron density of palladium and a downward shift of the d-band center. After that, electrons transfer from the C atom through the P atom to the Pd atom, forming stable Pd 15 P2 species and electron-rich Pd. Effective electron-rich hydrogen is formed on the hydrogen adsorption active site, effectively realizing the inhibitory effect on C-Cl hydrogenation and reducing the dehalogenation side reaction. After losing phosphorus modification, the dehalogenation side reaction increases significantly.

[0051] In Comparative Example 2, the silicon carbide microspheres were directly used as chitosan / silicon carbide microspheres. During the carbonization process, a carbon layer will be formed on the surface of the chitosan layer of chitosan / silicon carbide microspheres, further increasing the strength of the carbon microspheres and avoiding stress concentration caused by the etching of silicon dioxide by HF, thus preventing structural collapse. The chitosan structural formula contains N element, and after calcination, nitrogen-doped hollow silicon carbide microspheres can be formed. Nitrogen element 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 element further stabilizes the palladium metal particles. After losing the chitosan layer, the ability to inhibit the dehalogenation side reaction decreases.

[0052] In Comparative Example 3, 2,5-diaminoterephthalic acid was omitted, and the formation of MOF-Pd on the surface was achieved by using hollow silicon carbide microspheres as the carrier. After the MOF was carbonized, a graphitized carbon layer was formed to wrap the palladium particles, inhibiting high-temperature aggregation, thereby realizing the dispersion and fixation of palladium. Without 2,5-diaminoterephthalic acid, MOF-Pd cannot be generated, and thus palladium cannot be effectively fixed.

[0053] It should be noted that in this article, terms such as "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device.

[0054] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A catalytic synthesis process for indoxacarb intermediate, the catalytic synthesis process comprising: Under alkaline conditions, YCW-5 undergoes a hydrogenation reaction using methyl acetate as a solvent and a palladium phosphide-carbon-based catalyst. An indoxacarb intermediate is obtained. It is characterized in that the palladium phosphide-carbon-based catalyst is prepared by the following steps: Step 1: Co-precipitate silica on the surface of microspherical polymers assembled by sucrose hydrothermal reaction to obtain carbon-silica microspheres. Utilize the hydroxyl groups on the surface of the carbon-silica microspheres and the amino groups in chitosan to undergo a hydroxyamination reaction to obtain chitosan / carbon-silica microspheres with a chitosan layer coated on the surface; Step 2: Esterify the hydroxyl groups on the surface of the chitosan / silicon-carbon microspheres with the phosphate groups of cyclohexanehexol hexaphosphate, and then pyrolyze in a muffle furnace. Wash away the silica using hydrofluoric acid to obtain hollow palladium phosphide-carbon microspheres; Step 3: Load MOF-Pd using the hollow palladium phosphide-carbon microspheres as a carrier. After the MOF is carbonized, a palladium phosphide-carbon-based catalyst is obtained.

2. The catalytic synthesis process of indoxacarb intermediate according to claim 1, wherein, The specific preparation steps of the carbon-silica microspheres in Step 1 are as follows: Add a 30-35 wt% sucrose solution to a stainless-steel reaction kettle with a polytetrafluoroethylene liner. Stir at 20-25 °C and 500-600 r / min for 10-12 min, heat to 180-200 °C and continue stirring for 3-4 h. Then add tetraethyl orthosilicate, anhydrous ethanol, and 20-30 wt% ammonia water, and continue stirring and reacting for 8-10 h. Filter, wash, dry under vacuum, transfer to a muffle furnace, and calcine at 750-800 °C for 12-14 h in an argon atmosphere to obtain carbon-silica microspheres.

3. The catalytic synthesis process of indoxacarb intermediate according to claim 2, wherein The dosage 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 indoxacarb intermediate according to claim 1, characterized in that, The specific preparation steps of the chitosan / carbon-silica microspheres in Step 2 are as follows: Add chitosan, a 20-30 wt% hydrochloric acid solution, cetyltrimethylammonium bromide, and a 20-25 wt% ethanol solution to the reaction kettle. Stir at 20-25 °C and 500-600 r / min for 20-30 min, then add the carbon-silica microspheres, and continue stirring for 5-6 h. Filter, wash, dry under vacuum to obtain chitosan / carbon-silica microspheres.

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

6. The catalytic synthesis process of indoxacarb intermediate according to claim 1, characterized in that, The specific preparation steps of the hollow palladium phosphide-carbon microspheres in Step 2 are as follows: Add chitosan / carbon-silica microspheres, cyclohexanehexol hexaphosphate, and N,N-dimethylformamide to the reaction kettle. Heat to 90-100 °C and continue stirring for 2-3 h, cool naturally, filter, wash, dry under vacuum to obtain palladium phosphide-carbon-silica microspheres; transfer the palladium phosphide-carbon-silica microspheres to a muffle furnace, heat to 350-370 °C in an argon atmosphere and calcine for 2-3 h, heat to 900-950 °C at a rate of 5-6 °C / min, hold for 2-3 h, and wash the product with a 5 wt% hydrofluoric acid solution and deionized water to obtain hollow palladium phosphide-carbon microspheres.

7. A catalytic synthesis process of indoxacarb intermediate according to claim 6, characterized in that, The dosage 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 indoxacarb intermediate according to claim 1, characterized in that, The specific preparation steps of the palladium phosphide carbon-based catalyst in step three are as follows: Add the hollow palladium phosphide carbon microspheres, 2,5-diaminoterephthalic acid and deionized water into the reaction kettle, stir at 70-80 °C and 400-500 r / min for 20-30 min, then add palladium nitrate, continue to stir and react for 4-6 h, filter, wash, and dry in vacuum. Transfer the product to a muffle furnace and calcine at 750-800 °C for 4-5 h under an argon atmosphere to obtain the palladium phosphide carbon-based catalyst.

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

10. A catalytic synthesis process of indoxacarb intermediate according to claim 1, characterized in that, The specific preparation steps of the indoxacarb intermediate are as follows: Add YCW-5, sodium acetate anhydrous, the palladium phosphide carbon-based catalyst and methyl acetate into the reaction kettle. At 10-15 °C, introduce hydrogen at a rate of 10-20 mL / min for 1-2 min for replacement, discharge the gas, and perform hydrogen replacement 2-3 times at the same rate. Continue to react for 6-7 h to obtain an indoxacarb intermediate and complete the catalytic synthesis process; Further, the dosage ratio of YCW-5, sodium acetate anhydrous, the 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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