Preparation method of anti-dechlorination catalyst and application of anti-dechlorination catalyst in hydrogenation of sulfentrazone intermediate

Abstract

The invention relates to the field of chemical synthesis, discloses a preparation method of an anti-dechlorination catalyst and application of the anti-dechlorination catalyst in hydrogenation of a sulfentrazone intermediate, and provides a high-activity and high-selectivity anti-dechlorination platinum-based catalyst which can realize anti-dechlorination nitro hydrogenation of a triazolinone-containing intermediate. Compared with a Pt / C catalyst with high noble metal loading capacity in the prior art, the content of the active component Pt of the catalyst can be as low as about 1.0 wt%, the number of times of applying stability of the catalyst is increased, the number of times of activating the catalyst is reduced, the production cost can be reduced, and the proportion of dechlorination byproducts in the conversion process is reduced; the crystallized crude product is white and stable in appearance, and the product quality is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and specifically discloses a preparation method of a dechlorination-proof catalyst and its application in the hydrogenation of the intermediate of tembotrione. Background Art

[0002] Tembotrione is a broad-spectrum selective herbicide belonging to the HPPD inhibitor herbicides, mainly used for controlling gramineous weeds and some broad-leaved weeds in corn fields. By inhibiting hydroxyphenylpyruvate dioxygenase (HPPD), it interferes with the synthesis of carotenoids in plants, resulting in the chlorosis and withering of plant leaves and finally death. The action mechanism of tembotrione has a good control effect on a variety of weeds and is safe for crops.

[0003] A variety of synthetic routes of tembotrione are disclosed in the prior art. For example, in Patent US4980480A, a method of synthesizing the intermediate of tembotrione using monochloroaniline and aniline is adopted, such as:

[0004] The advantages of this route are low raw material cost and small steric hindrance of intermediate products, but it faces the problem of low chlorination yield. Further nitration of the raw materials leads to the fact of low purity. Among them, the reduction method uses a iron powder catalyst for reduction, which easily generates a large amount of iron-containing wastewater and has high requirements for the catalyst.

[0005] Patent CN 104326992 A "A Method for Synthesizing Difluoromethyl Triazolinone and Tembotrione" is to use a Pd / C catalyst in a methanol solvent and obtain the intermediate of tembotrione by pressurized hydrogen under the reaction conditions of 0.5 MPa and 60 °C;

[0006] In the process of hydrogenation of the tembotrione intermediate in an alcohol system, after the catalyst is recycled multiple times, the catalytic reaction rate gradually decreases, and the recycling times of the catalyst are relatively low. It needs to be frequently activated to maintain its activity, resulting in relatively high production costs. The reason is that there are unstable hydroxylamines and azo that are not completely converted during the conversion process from nitro to amino in the product. CN103951627A mentions the use of a Pt / C catalyst, but the Pt / C catalyst undergoes dechlorination at the ortho position of the amino group during the hydrogenation process, which puts higher requirements on the activity and selectivity of the catalyst. Summary of the Invention

[0007] In order to solve the problems in the prior art, the first aspect of the present invention proposes a preparation method of a Pt / Sn-Al2O3 catalyst, including: Step 1: Mix an aqueous solution of sodium stannate with alumina to obtain a mixture; Step 2: In an inert atmosphere, the mixture is heated to a first predetermined temperature and calcined to obtain an alumina support treated with tin. Step 3: The alumina support treated with tin is mixed with water to obtain a dispersion liquid, and an aqueous solution of chloroplatinic acid is added dropwise to the dispersion liquid to obtain an impregnation liquid. Step 4: An alkali and a reducing agent are added to the impregnation liquid, and after solid-liquid separation, the catalyst Pt / Sn-Al2O3 is obtained.

[0008] In some specific embodiments of the first aspect, the concentration of sodium stannate in water in Step 1 is 34.8 - 71.6 g / L. In some embodiments, the concentration of sodium stannate in water in Step 1 is 45.0 g / L. In some embodiments, the concentration of sodium stannate in water in Step 1 is 55.0 g / L. In some embodiments, the concentration of sodium stannate in water in Step 1 is 65.0 g / L.

[0009] In some specific embodiments of the first aspect, the specification of the alumina in Step 1 is 150 - 200 mesh. In some embodiments, the specification of the alumina in Step 1 is 160 mesh. In some embodiments, the specification of the alumina in Step 1 is 170 mesh. In some embodiments, the specification of the alumina in Step 1 is 180 mesh.

[0010] In some specific embodiments of the first aspect, in Step 1, 1.25 - 2.5 g of alumina is mixed with every 1 ml of the aqueous solution of sodium stannate. In some specific embodiments of the first aspect, in Step 1, 1.50 g of alumina is mixed with every 1 ml of the aqueous solution of sodium stannate. In some specific embodiments of the first aspect, in Step 1, 1.75 g of alumina is mixed with every 1 ml of the aqueous solution of sodium stannate. In some specific embodiments of the first aspect, in Step 1, 2.00 g of alumina is mixed with every 1 ml of the aqueous solution of sodium stannate.

[0011] In some specific embodiments of the first aspect, in Step 1, after the aqueous solution of sodium stannate is mixed with alumina, it is exposed to air for 2 - 5 h for aging. In some specific embodiments of the first aspect, in Step 1, after the aqueous solution of sodium stannate is mixed with alumina, it is exposed to air for 3 h for aging. In some specific embodiments of the first aspect, in Step 1, after the aqueous solution of sodium stannate is mixed with alumina, it is exposed to air for 4 h for aging.

[0012] In some specific embodiments of the first aspect, the inert atmosphere in Step 2 is any one of an argon atmosphere and a nitrogen atmosphere.

[0013] In some specific embodiments of the first aspect, in Step 2, the heating rate of the mixture is 4 - 6 °C / min. In some specific embodiments of the first aspect, in Step 2, the heating rate of the mixture is 5 °C / min.

[0014] In some specific embodiments of the first aspect, in step 2, the first predetermined temperature is 400 - 450 °C. In some specific embodiments of the first aspect, in step 2, the first predetermined temperature is 420 °C. In some specific embodiments of the first aspect, in step 2, the first predetermined temperature is 440 °C.

[0015] In some specific embodiments of the first aspect, in step 3, the concentration of the aqueous solution of chloroplatinic acid is 25.4 - 50.8 g / L. In some specific embodiments of the first aspect, in step 3, the concentration of the aqueous solution of chloroplatinic acid is 30.0 g / L. In some specific embodiments of the first aspect, in step 3, the concentration of the aqueous solution of chloroplatinic acid is 40.0 g / L.

[0016] In some specific embodiments of the first aspect, the preparation method of the dispersion is as follows: 150 - 250 g of alumina support pretreated with tin is added to every 1 L of ultrapure water. In some specific embodiments of the first aspect, the preparation method of the dispersion is as follows: 175 g of alumina support pretreated with tin is added to every 1 L of ultrapure water. In some specific embodiments of the first aspect, the preparation method of the dispersion is as follows: 225 g of alumina support pretreated with tin is added to every 1 L of ultrapure water.

[0017] In some specific embodiments of the first aspect, in step 4, the alkali concentration is 0.8 - 1.2 mol / L. In some specific embodiments of the first aspect, in step 4, the alkali concentration is 0.9 mol / L. In some specific embodiments of the first aspect, in step 4, the alkali concentration is 10.0 mol / L. In some specific embodiments of the first aspect, in step 4, the alkali concentration is 1.1 mol / L.

[0018] In some specific embodiments of the first aspect, in step 4, the reducing agent is an aqueous solution of the reducing agent, and the concentration of the aqueous solution of the reducing agent is 4.5 - 5.5 mol / L. In some specific embodiments of the first aspect, the concentration of the aqueous solution of the reducing agent is 4.7 mol / L. In some specific embodiments of the first aspect, the concentration of the aqueous solution of the reducing agent is 5.0 mol / L. In some specific embodiments of the first aspect, the concentration of the aqueous solution of the reducing agent is 5.2 mol / L.

[0019] The second aspect of the present invention provides a Pt / Sn - Al2O3 catalyst prepared according to any one of the embodiments of the first aspect.

[0020] The third aspect of the present invention provides an application of the catalyst described in the second aspect in the hydrogenation reaction of the sulfentrazone intermediate.

[0021] A fourth aspect of the present aspect provides a method for hydrogenating the sulfentrazone intermediate, comprising:

[0022] Mix the Pt / Sn-Al2O3 catalyst described in the second aspect with the sulfentrazone intermediate shown in Formula 1 and toluene solvent, pressurize under a hydrogen atmosphere, and raise the temperature to a second predetermined temperature to obtain the sulfentrazone intermediate shown in Formula 2.

[0023] In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the hydrogen pressure is 0.5 MPa or more.

[0024] In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the heating rate is 8 - 12 °C / min. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the heating rate is 10 °C / min.

[0025] In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the second predetermined temperature is 80 - 120 °C. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the second predetermined temperature is 90 °C. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the second predetermined temperature is 100 °C.

[0026] In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the catalyst feeding amount is 0.4 - 0.6% of the mass of the sulfentrazone intermediate shown in Formula 1. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, the catalyst feeding amount is 0.5% of the mass of the sulfentrazone intermediate shown in Formula 1.

[0027] In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, 150 - 200 g of the sulfentrazone intermediate shown in Formula 1 is added to each 1 L of the toluene. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, 170 g of the sulfentrazone intermediate shown in Formula 1 is added to each 1 L of the toluene. In some specific embodiments of the method for hydrogenating the sulfentrazone intermediate according to the fourth aspect of the present invention, 190 g of the sulfentrazone intermediate shown in Formula 1 is added to each 1 L of the toluene.

[0028] The medicaments used in the present invention are all purchased from publicly legal markets and are not further purified.

[0029] The by-product 3 in the present invention has a structural formula as follows: .

[0030] All the reagents used in the present invention are purchased from the open and legal market and have not been further purified.

[0031] The CAS number of hydroxymethyltributylstannane in the present invention is 27490-33-1.

[0032] Advantages of the present invention: The present invention provides a highly active and highly selective dechlorination-resistant platinum-based tin-modified alumina catalyst, which can realize the dechlorination-resistant nitrohydrogenation of triazolinone intermediates under the condition of reducing the influence of ortho-dechlorination side reactions. Compared with the Pt / C catalyst with a high noble metal loading amount in the prior art, the content of the active component Pt in the catalyst of the present invention can be as low as about 1.0 wt%, and the stable reuse times of the catalyst increase, reducing the activation frequency of the catalyst, which can reduce the production cost and reduce the proportion of dechlorination by-products in the conversion process, making the appearance of the crude crystal product of the present invention white and stable, and the product quality is significantly improved. Specific embodiments

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be noted that these embodiments are only used to illustrate the present invention and do not limit the present invention in any way. The improvements and adjustments made by those skilled in the art based on the present invention in actual applications still fall within the protection scope of the present invention.

[0034] Example 1 Tin pretreatment step of alumina support: Tin-alumina spraying and aging: (1) Weigh 1.74 g of sodium stannate solid and 50 ml of water, mix the two, stir until completely dissolved, weigh 100 g of alumina with a specification of 200 mesh, and place it in a 500 ml clean beaker. Subsequently, spray the aqueous solution of sodium stannate onto the surface of alumina and keep stirring and mixing. After spraying, place it in the air for aging for 4 h.

[0035] Support calcination treatment: (2) The aged solid powder is heated to 450 °C at a rate of 5 °C / min in an N2 atmosphere and calcined for 4 h. The support after tin treatment is obtained.

[0036] Platinum loading step: Platinum loading: (1) Take 12.70 g of chloroplatinic acid solid, add 100 ml of ultrapure water, and dissolve it with ultrasonic assistance until the solid sample is completely dissolved and clarified. Transfer the obtained chloroplatinic acid solution to a 250 ml volumetric flask for volume fixation. Weigh 10 g of the above-mentioned support pretreated with tin, disperse it in 50 ml of ultrapure water to obtain a dispersion, accurately measure 10.2 ml of the above-mentioned chloroplatinic acid solution, and drop it into the dispersion. After dropping, continue to stir and disperse for 30 min.

[0037] Catalyst reduction: (2) 40 ml of an aqueous NaOH solution with a concentration of 1 mol / L and 3 ml of an aqueous NaBH4 solution with a concentration of 5 mol / L were simultaneously added dropwise to the dispersion. After continuing to stir and disperse for 1 h, solid-liquid separation was carried out, and the filter cake was washed with ultrapure water to obtain the catalyst Pt / Sn-Al2O3, numbered Cat-1.

[0038] Example 2 Tin pretreatment step of the alumina support: Tin-alumina spraying and aging: (1) Weigh 3.58 g of sodium stannate solid and 50 ml of water, mix the two, stir until completely dissolved, weigh 100 g of alumina with a specification of 200 mesh, and place it in a 500 ml clean beaker. Subsequently, the aqueous solution of sodium stannate was sprayed onto the surface of the alumina, and stirring and mixing were maintained. After spraying, it was left to age in the air for 4 h.

[0039] Support calcination treatment: (2) The aged solid powder was heated to 350 °C at a rate of 3 °C / min in a N2 atmosphere and calcined for 4 h. The tin-treated support was obtained.

[0040] Platinum loading step: Platinum loading: (1) Take 6.35 g of chloroplatinic acid solid, add 100 ml of ultrapure water, and dissolve it with ultrasonic assistance until the solid sample is completely dissolved and clear. Transfer the obtained chloroplatinic acid solution to a 250 ml volumetric flask for volume fixation. Weigh 10 g of the above-mentioned tin-pretreated support, disperse it in 50 ml of ultrapure water to obtain a dispersion, accurately measure 10.2 ml of the above-mentioned chloroplatinic acid solution, and add it dropwise to the dispersion. After dropping, continue to stir and disperse for 30 min.

[0041] Catalyst reduction: (2) 25 ml of an aqueous NaOH solution with a concentration of 1 mol / L and 2 ml of an aqueous NaBH4 solution with a concentration of 5 mol / L were simultaneously added dropwise to the dispersion. After continuing to stir and disperse for 1 h, solid-liquid separation was carried out, and the filter cake was washed with ultrapure water to obtain the catalyst, numbered Cat-2.

[0042] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the support in Comparative Example 1 uses activated carbon as the support, and the preparation method of this activated carbon support is as follows: (1) Weigh 100 g of activated carbon with a specification of 80 mesh and place it in a 500 ml clean beaker. Subsequently, the aqueous solution of sodium stannate in Example 1 was sprayed onto the surface of the activated carbon, and stirring and mixing were maintained. After spraying, it was left to age for 4 h.

[0043] Carbon support calcination treatment: (2) The aged solid powder was heated to 450 °C at a rate of 5 °C / min in a N2 atmosphere and calcined for 4 h. The tin-treated carbon support was obtained.

[0044] Platinum loading step: Platinum loading: (1) Take 12.70 g of chloroplatinic acid solid, add 100 ml of ultrapure water, and dissolve it with ultrasonic assistance until the solid sample is completely dissolved and clear. Transfer the obtained chloroplatinic acid solution to a 250-ml volumetric flask for volume fixation. Weigh 10 g of the above-mentioned carrier pretreated with tin, disperse it in 50 ml of ultrapure water to obtain a dispersion. Accurately measure 10.2 ml of the above-mentioned chloroplatinic acid solution and add it dropwise to the dispersion. After the addition is complete, continue to stir and disperse for 30 min.

[0045] Catalyst reduction: (2) Simultaneously add 40 ml of 1 mol / L NaOH aqueous solution and 3 ml of 5 mol / L NaBH4 aqueous solution dropwise to the dispersion. After continuing to stir and disperse for 1 h, perform solid-liquid separation and wash the filter cake with ultrapure water to obtain the catalyst Pt / Sn-C, numbered Cat-3.

[0046] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the alumina carrier is not pretreated with tin, and the rest is the same. The treatment of the carrier in Comparative Example 2 is as follows: Aging of alumina carrier: (1) Weigh 100 g of alumina with a mesh size of 200 and place it in a 500-ml clean beaker without spraying the surface with an aqueous solution of sodium stannate. (2) In an N2 atmosphere, heat the alumina powder at a rate of 5 °C / min to 450 °C and calcine for 4 h to obtain the alumina carrier.

[0047] Platinum loading step: Platinum loading: (1) Take 12.70 g of chloroplatinic acid solid, add 100 ml of ultrapure water, and dissolve it with ultrasonic assistance until the solid sample is completely dissolved and clear. Transfer the obtained chloroplatinic acid solution to a 250-ml volumetric flask for volume fixation. Weigh 10 g of the above-mentioned alumina carrier, disperse it in 50 ml of ultrapure water to obtain a dispersion. Accurately measure 10.2 ml of the above-mentioned chloroplatinic acid solution and add it dropwise to the dispersion. After the addition is complete, continue to stir and disperse for 30 min.

[0048] Catalyst reduction: (2) Simultaneously add 40 ml of 1 mol / L NaOH aqueous solution and 3 ml of 5 mol / L NaBH4 aqueous solution dropwise to the dispersion. After continuing to stir and disperse for 1 h, perform solid-liquid separation and wash the filter cake with ultrapure water to obtain the catalyst Pt / Al2O3, numbered Cat-4.

[0049] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that in the tin pretreatment process of the alumina carrier, the tin-alumina spraying and aging step uses hydroxymethyltributylstannane, and the rest is the same. The tin-alumina spraying and aging step in Comparative Example 3 is as follows: Tin-aluminum oxide spraying aging: (1) Mix 2.63 g of hydroxymethyl tributylstannane and 50 ml of methanol, stir until completely dissolved, weigh 100 g of alumina with a specification of 200 mesh, and place it in a 500 ml clean beaker. Subsequently, spray the methanol solution of hydroxymethyl tributylstannane onto the surface of the alumina, and keep stirring and mixing. After spraying, let it age until the surface of the alumina is dry.

[0050] After the same Pt loading and catalyst reduction steps as in Example 1, a catalyst was obtained, numbered Cat-5.

[0051] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, platinum nitrate is used instead of chloroplatinic acid in the platinum loading step, and the rest is the same. The platinum loading step in Comparative Example 4 is as follows: Platinum loading: (1) Take 9.90 g of platinum nitrate solid, add 100 ml of ultrapure water, and dissolve it with ultrasonic assistance until the solid sample is completely dissolved and clear. Transfer the obtained platinum nitrate solution to a 250 ml volumetric flask for volume fixation. Weigh 10 g of the above-mentioned carrier pretreated with tin, disperse it in 200 ml of ultrapure water to obtain a dispersion. Accurately measure 10.2 ml of the above-mentioned platinum nitrate solution and add it dropwise to the dispersion. After dropping, continue to stir and disperse for 24 h.

[0052] After the same catalyst sintering and forming steps as in Example 1, a catalyst was obtained, numbered Cat-6.

[0053] Example 3:

[0054] Use a 500 ml reactor, put 20 g of the raw material 1 of the sulfentrazone intermediate into the reactor, add 100 ml of toluene solvent and the catalyst shown in Table 1, and add the catalyst at 0.5 wt% of the raw material weight. Control the reactor to heat up to 40 °C, introduce 0.5 MPa of hydrogen, and then heat up at a speed of 10 °C / min until the final reaction temperature reaches 100 °C and maintain it for 45 min. After opening the reactor, take samples for liquid chromatography analysis of the yield of sulfentrazone in Formula 2, and conduct multiple applications of the catalyst. When the yield of sulfentrazone in Formula 2 in the current application is less than 90% of the initial yield, record the number of applications. The results are shown in Table 1.

[0055] Table 1 Among them: "The number of applications is the number of times the catalyst is recycled until the yield is lower than 90% of the initial yield".

[0056] Example 4: A 500 ml reactor was used. 20 g of the raw material of the sulfentrazone intermediate 1 was charged into the reactor, and 100 ml of the solvent and the catalyst Cat-1 shown in Table 2 were charged. The catalyst was added at 0.5 wt% based on the weight of the raw material. The reactor was controlled to an initial temperature of 40 °C, 0.5 MPa of hydrogen was introduced, and the temperature was increased at a rate of T1 °C / min. Finally, the reaction temperature reached and was maintained at T2 °C for 45 min. After opening the reactor, samples were taken for liquid chromatography analysis. The catalyst was reused for multiple times. When the yield of the current reuse was less than 90% of the initial yield, the number of reuse times was recorded. The results are shown in Table 2.

[0057] Table 2 The method of the present invention has been described through preferred embodiments. It is obvious that relevant personnel can make changes or appropriate modifications and combinations to the methods and applications described herein within the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention.

Claims

1. A method for preparing an anti-dechlorination catalyst Pt / Sn-Al2O3, comprising: Step 1: mixing an aqueous solution of sodium stannate with aluminum oxide to obtain a mixture; Step 2: In an inert atmosphere, the mixture is heated to a first predetermined temperature and calcined to obtain a tin-treated alumina carrier; Step 3: mixing the tin-treated alumina carrier with water to obtain a dispersion, and adding an aqueous solution of chloroplatinic acid to the dispersion to obtain an impregnation solution; Step 4: Add alkali and reducing agent to the impregnation solution, and obtain the catalyst Pt / Sn-Al2O3 after solid-liquid separation.

2. The method for preparing the Pt / Sn-Al2O3 catalyst according to claim 1, characterized in that: In the step 1, the concentration of sodium stannate in water is 34.8-71.6 g / L, and / or, the specification of alumina in the step 1 is 150-200 mesh, and / or, in the step 1, 1.25-2.5 g of alumina is mixed with every 1 ml of sodium stannate aqueous solution, and / or, in the step 1, after the sodium stannate aqueous solution is mixed with alumina, it is exposed to air for 2-5 hours of aging.

3. The method for preparing the Pt / Sn-Al2O3 catalyst according to any one of claims 1 or 2, characterized in that: In step 2, the inert atmosphere is any one of argon atmosphere and nitrogen atmosphere, and / or, in step 2, the heating rate of the mixture is 4-6°C / min, and / or, in step 2, the first predetermined temperature is 400-450°C.

4. The method for preparing the Pt / Sn-Al2O3 catalyst according to any one of claims 1 to 3, characterized in that: In the step 3, the concentration of the aqueous solution of chloroplatinic acid is 25.4-50.8 g / L, and / or, in the step 3, the dispersion is configured by adding 150-250 g of alumina carrier pretreated with tin into every 1 L of ultrapure water.

5. The method for preparing the Pt / Sn-Al2O3 catalyst according to any one of claims 1 to 4, characterized in that: In step 4, the base is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water, the reducing agent is selected from one or more of NaBH4, KBH4, hydrazine hydrate, formaldehyde, and formic acid, and / or the reducing agent concentration is 4.5-5.5 mol / L, and / or the base concentration is 0.8-1.2 mol / L.

6. A Pt / Sn-Al2O3 catalyst prepared by the method of any one of claims 1 to 5.

7. Use of the catalyst according to claim 6 in the hydrogenation reaction of sulfentrazone intermediates.

8. A method for hydrogenating a sulfentrazone intermediate, comprising: ； The Pt / Sn-Al2O3 catalyst of claim 6 is mixed with the sulfentrazone intermediate of formula 1 and a toluene solvent, pressurized under a hydrogen atmosphere, and heated to a second predetermined temperature to obtain the sulfentrazone of formula 2.

9. The method for hydrogenating a sulfentrazone intermediate according to claim 8, characterized in that: The hydrogen pressure is above 0.5 MPa, and / or the heating rate is 8-12° C. / min, and / or the second predetermined temperature is 80-120° C.

10. The method for hydrogenating a sulfentrazone intermediate according to any one of claims 8 or 9, characterized in that: The catalyst feed amount is 0.4-0.6% of the mass of the sulfentrazone intermediate shown in Formula 1, and / or 150-200 g of the sulfentrazone intermediate shown in Formula 1 is added to every 1 L of the toluene.

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