Green synthesis process of flumioxazin

Abstract

The invention relates to the technical field of organic synthesis, in particular to a green synthesis process of flumioxazin, which comprises the following steps: S1) taking 6-amino-7-fluoro-4-propinyl-1, 4-benzoxazine-3 (4H) ketone and 3, 4, 5, 6-tetrahydrophthalic anhydride as raw materials, carrying out first reaction at-20 to 50 DEG C, and filtering to obtain a first solid; and S2) carrying out a second reaction on the first solid at 80-120 DEG C to obtain the flumioxazin. According to the method, the temperature of the first reaction is controlled to generate the first solid as the intermediate, the obtained first solid is filtered to effectively remove the impurities by utilizing the characteristic that the intermediates and the impurities have different solubilities in different solvents, and then the second reaction is performed to obtain the flumioxazin, so that the subsequent product does not need recrystallization / pulping operation, and the yield is high. The target product almost has no separation loss. The method provided by the invention is mild in reaction condition, simple in post-treatment and high in product yield and purity.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a green synthesis process of fluazifop-butyl. Background Art

[0002] Fluazifop-butyl is an N-phenylphthalimide herbicide launched by Sumitomo Chemical Co., Ltd. of Japan in 1993. It is mainly used to control grass weeds and broad-leaved weeds in crops such as soybeans, sugarcane, and cotton. It is easily degraded in the environment and is safe for subsequent crops. Therefore, it is widely used in agricultural production and has huge economic market value.

[0003] At present, the synthesis of fluazifop-butyl generally uses 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one as raw material. The existing synthesis method has high requirements on the purity of the raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one, and the raw material needs to be purified in advance. The purification method is generally recrystallization or acid dissolution and alkali precipitation, activated carbon adsorption, which not only increases the operating procedures and increases the manufacturing cost, but also causes the loss of raw materials during the purification process, increasing the cost of raw materials. On the other hand, after the synthesis of fluazifop-butyl, the existing technology needs to be recrystallized / pulped to purify in order to obtain qualified products. The post-processing process is cumbersome and energy-intensive, and it is difficult to take into account both yield and purity at the same time. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a green synthesis process of fluazifop-butyl with higher yield and purity.

[0005] The present invention provides a green synthesis process of fluazifop-butyl, comprising the following steps:

[0006] S1) using 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one and 3,4,5,6-tetrahydrophthalic anhydride as raw materials, performing a first reaction at -20 to 50° C., and filtering to obtain a first solid;

[0007] S2) subjecting the first solid to a second reaction at 80-120° C. to obtain fluazifop-butyl.

[0008] Optionally, the temperature of the first reaction is -10 to 30°C;

[0009] The temperature of the second reaction is 85-110°C.

[0010] Optionally, the solvents for the first reaction and the second reaction are independently selected from one or more of ethers, inert halogenated hydrocarbons, organic acids and aprotic solvents.

[0011] Optionally, the inert halogenated hydrocarbon is selected from ethylene dichloride;

[0012] The organic acid is selected from one or more of formic acid, acetic acid and propionic acid;

[0013] The aprotic solvent is selected from one or more of DMF, N,N-dimethylacetamide, and methyl isobutyl ketone.

[0014] Optionally, the solvents for the first reaction and the second reaction are independently selected from one or more of ethylene dichloride, acetic acid, propionic acid, DMF, and methyl isobutyl ketone.

[0015] Optionally, the amount of the solvent used in the first reaction is 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one;

[0016] The amount of solvent used in the second reaction is 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one.

[0017] Optionally, the molar ratio of the 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one to 3,4,5,6-tetrahydrophthalic anhydride is 1:(1-1.5).

[0018] Optionally, after the second reaction is completed, the reaction system is cooled to 20-25° C., filtered and dried to obtain fluazifop-butyl.

[0019] Optionally, the first reaction time is 0.5 to 2 hours.

[0020] Compared with the prior art, the present invention provides a green synthesis process of fluazifop-butyl, comprising the following steps: S1) using 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one and 3,4,5,6-tetrahydrophthalic anhydride as raw materials, performing a first reaction at -20 to 50°C, and filtering to obtain a first solid; S2) subjecting the first solid to a second reaction at 80 to 120°C to obtain fluazifop-butyl. The present invention controls the temperature of the first reaction so that the reaction generates a first solid as an intermediate, and utilizes the different solubility of the intermediate and impurities in different solvents to filter the obtained first solid to effectively remove impurities, and then performs a second reaction to obtain fluazifop-butyl, and the subsequent product does not require recrystallization / slurrying operations, and the target product has almost no separation loss.

[0021] The method provided by the invention has mild reaction conditions. After fluazifop-butyl is obtained by reaction, no recrystallization or pulping purification operation is required, so the post-processing operation is simplified, the energy consumption is reduced, the yield of fluazifop-butyl is high, and the product quality is high. In addition, the purity requirement for the raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one is not high, and industrial production is easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a synthetic process flow chart of fluazifop-butyl. DETAILED DESCRIPTION

[0023] The present invention provides a green synthesis process of fluazifop-butyl, comprising the following steps:

[0024] S1) using 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one and 3,4,5,6-tetrahydrophthalic anhydride as raw materials, performing a first reaction at -20 to 50° C., and filtering to obtain a first solid;

[0025] S2) subjecting the first solid to a second reaction at 80-120° C. to obtain fluazifop-butyl.

[0026] The equation for the above reaction is speculated as follows:

[0027]

[0028] The above formula IV is the intermediate obtained by the first reaction.

[0029] The temperature of the first reaction is preferably -20 to 50°C, for example, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc., more preferably -10 to 30°C, and even more preferably 10°C.

[0030] The solvent for the first reaction is preferably one or more of ether, inert halogenated hydrocarbon, organic acid and aprotic solvent.

[0031] The above-mentioned inert halogenated hydrocarbon is preferably ethylene dichloride.

[0032] The organic acid is preferably one or more of formic acid, acetic acid and propionic acid.

[0033] The aprotic solvent is preferably one or more of DMF, N,N-dimethylacetamide, and methyl isobutyl ketone.

[0034] More preferably, the solvent of the first reaction is preferably one or more of ethylene dichloride, acetic acid, propionic acid, DMF, and methyl isobutyl ketone.

[0035] In some specific embodiments of the present invention, the solvent of the first reaction is acetic acid, propionic acid, DMF, methyl isobutyl ketone, a mixed solvent of ethylene dichloride and acetic acid, or a mixed solvent of ethylene dichloride and DMF.

[0036] The choice of the above solvent can further improve the reaction yield.

[0037] The amount of the solvent used in the first reaction is preferably 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one, for example, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times or 15 times, more preferably 3 to 6 times, and further preferably 5 to 6 times.

[0038] The molar ratio of the 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one to 3,4,5,6-tetrahydrophthalic anhydride is preferably 1:(1-1.5), for example, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, more preferably 1:(1-1.3).

[0039] The present invention has no special restriction on the order of adding the 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)ketone, 3,4,5,6-tetrahydrophthalic anhydride and solvent. Considering the convenience of industrial production, the solvent and 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)ketone are preferably mixed, and then 3,4,5,6-tetrahydrophthalic anhydride is added.

[0040] Further, the present invention has no special limitation on the method of adding the 3,4,5,6-tetrahydrophthalic anhydride, and the 3,4,5,6-tetrahydrophthalic anhydride can be added in a manner known to those skilled in the art, such as continuous addition, batch addition or all-at-one addition. Among them, since the above reaction is an exothermic reaction, in order to better control the temperature stability of the system, a batch addition method is generally adopted. Preferably, the addition time of the 3,4,5,6-tetrahydrophthalic anhydride is less than or equal to 0.5h.

[0041] In some specific embodiments of the present invention, the solvent and 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one are first mixed, and then the temperature is controlled to the reaction temperature and 3,4,5,6-tetrahydrophthalic anhydride is added in batches. After adding 3,4,5,6-tetrahydrophthalic anhydride, the temperature is kept constant for the first reaction, and the reaction is considered qualified when 1% of the raw materials remain, and the reaction is terminated.

[0042] The time of the first reaction is preferably 0.5 to 2 h, for example, 0.5 h, 1 h, 1.5 h, or 2 h, more preferably 0.5 to 1.5 h, and even more preferably 1 h.

[0043] Preferably, after the reaction of the above-mentioned 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)ketone and 3,4,5,6-tetrahydrophthalic anhydride is completed, the impurities in the system are removed by filtering to obtain the first solid, i.e., the intermediate shown in formula (IV). Since the solubility of the intermediate shown in formula (IV) in the solvent is extremely low, and the organic impurities in the raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)ketone are easily soluble in the solvent, the above-mentioned post-treatment method can effectively remove the organic impurities without causing the loss of the target product. The above-mentioned post-treatment process is easy to operate, simple and easy to operate, and has low energy consumption; the impurity removal effect is obvious, and the target product will not be lost.

[0044] The obtained first solid is then subjected to a second reaction.

[0045] The temperature of the second reaction is preferably 80-120°C, for example 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, more preferably 85-110°C.

[0046] The solvent for the second reaction is preferably one or more of ether, inert halogenated hydrocarbon, organic acid and aprotic solvent.

[0047] The above-mentioned inert halogenated hydrocarbon is preferably ethylene dichloride.

[0048] The organic acid is preferably one or more of formic acid, acetic acid and propionic acid.

[0049] The aprotic solvent is preferably one or more of DMF, N,N-dimethylacetamide, and methyl isobutyl ketone.

[0050] More preferably, the solvent of the second reaction is preferably one or more of ethylene dichloride, acetic acid, propionic acid, DMF, and methyl isobutyl ketone.

[0051] In some specific embodiments of the present invention, the solvent of the second reaction is acetic acid, propionic acid, DMF, methyl isobutyl ketone, a mixed solvent of ethylene dichloride and acetic acid, or a mixed solvent of ethylene dichloride and DMF.

[0052] In some specific embodiments of the present invention, the solvent of the second reaction is the same as the solvent of the first reaction.

[0053] The amount of the solvent used in the above-mentioned second reaction is preferably 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one, for example, it can be 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times or 15 times, more preferably 3 to 6 times, and further preferably 5 to 6 times.

[0054] The present invention has no particular limitation on the reaction mode of the first reaction and the second reaction, which can be a reaction mode well known to those skilled in the art, such as being carried out under stirring. The present invention has no particular limitation on the stirring mode, which can be a commonly used mode in the prior art, including but not limited to mechanical stirring, magnetic stirring, shearing, etc.

[0055] The present invention has no special limitation on the time of the second reaction. It is sufficient to detect that the raw materials have reacted completely. Preferably, the reaction is considered to be completed when 1% of the raw materials remain. This process generally takes 0.5 to 3 hours.

[0056] After the second reaction is completed, the reaction system is cooled to 20-25° C., filtered and dried to obtain fluazifop-butyl.

[0057] The method provided by the present invention has low requirements on the purity of the raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one, and the purity can be 60% to 95%. The test results show that by using 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one with a purity of less than 90% as the reaction raw material, the reaction yield can also reach more than 95%, the product purity can reach more than 99%, and the appearance is an off-white powder without further recrystallization / slurrying.

[0058] In order to further illustrate the present invention, the following is a detailed description in conjunction with the embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0059] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0060] The content of fluazifop-butyl in the examples of the present invention was determined by high performance liquid chromatography.

[0061] In the following examples, unless otherwise specified, the content of 3,4,5,6-tetrahydrophthalic anhydride is 99%.

[0062] In the following examples and comparative examples, the product yield is the molar yield, which is calculated as follows: molar yield = product mass * product content / (product molecular weight * number of moles of raw material).

[0063] Example 1

[0064] To a 1000 mL reaction bottle, add 500 g of acetic acid, 100 g (0.36 mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)-one with a content of 80%, and add 58.6 g (0.38 mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and control a certain temperature (as shown in Table 1), and keep the temperature for 1.0 h. After the reaction is qualified, filter to obtain the intermediate. LC / MS, C 19 H 17 FN2O5, m / z = 373 (M + H + ).

[0065] Then the intermediate was put into a reaction bottle containing 500g of acetic acid, stirred and heated to 100°C. After the reaction was qualified, the temperature was lowered to 20-25°C, filtered and dried to obtain fluazifop-butyl. LC / MS, C 19 H 15 FN2O4, m / z = 355 (M + H + ).

[0066] 1 HNMR(CDCl3)δppm: 7.04(1H,d),6.89(1H,d),4.67(2H,d),4.50(2H,s),2.44(4H,t),2.30(1H,m),1.83(4H,m).

[0067] The purity and yield of the products obtained at different temperatures are shown in Table 1 below, as determined by HPLC.

[0068] Table 1

[0069] Reaction temperature Product Purity Product yield Product Appearance -20℃ 99.1％ 95.7％ Off-white powder -10℃ 99.4％ 96.0％ Off-white powder 10℃ 99.2％ 96.6％ Off-white powder 30℃ 99.3％ 96.2％ Off-white powder 50℃ 99.0％ 90.5％ Off-white powder

[0070] Example 2

[0071] Add 500g of the solvent shown in Table 2, 100g (0.36mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H) ketone with a content of 80% to a 1000mL reaction bottle, add 58.6g (0.38mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and control the temperature at 10°C, keep the reaction for 1.0h, and filter to obtain the intermediate after the reaction is qualified. Then put the intermediate into a reaction bottle containing 500g of solvent, stir and heat to 85°C, cool to 20-25°C after the reaction is qualified, filter and dry to obtain fluazifop-butyl.

[0072] The purity and yield of the products obtained in different solvents are shown in Table 2 below.

[0073] Table 2

[0074]

[0075] Example 3

[0076] Add 500g of dichloroethane and 100g (0.36mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H) ketone with a content of 80% to a 1000mL reaction bottle, add a certain amount of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and control at 10°C, keep warm for 1.0h, and filter to obtain an intermediate after the reaction is qualified. Then put the intermediate into a reaction bottle containing 500g of dichloroethane, stir and heat to 85°C, cool to 20-25°C after the reaction is qualified, filter and dry to obtain fluazifop-butyl.

[0077] The purity and yield of the product obtained by HPLC with different addition amounts of 3,4,5,6-tetrahydrophthalic anhydride are shown in the following table.

[0078] Table 3

[0079]

[0080]

[0081] Example 4

[0082] Add 500g of acetic acid and different contents of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)-one (0.36mol) to a 1000mL reaction bottle, add 58.6g (0.38mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and control at 20°C, keep warm for 1.0h, and filter to obtain an intermediate after the reaction is qualified. Then put the intermediate into a reaction bottle containing 500g of acetic acid, stir and heat to 100°C, cool to 20-25°C after the reaction is qualified, filter and dry to obtain fluazifop-butyl.

[0083] The purity and yield of the products obtained at different 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one contents were determined by HPLC and are shown in the following table.

[0084] Table 4

[0085] Raw material purity Product Purity Product yield Product appearance 60％ 99.1％ 95.6％ Off-white powder 70％ 99.2％ 95.9％ Off-white powder 80％ 99.4％ 96.2％ Off-white powder 90％ 99.5％ 96.5％ Off-white powder 95％ 99.5％ 96.4％ Off-white powder

[0086] The results in Table 4 show that, using the method provided by the present invention, the purity of the raw materials has little effect on the yield and purity of the product.

[0087] Example 5

[0088] Add 300g of acetic acid, 100g (0.36mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H) ketone with a content of 80% to a 1000mL reaction bottle, add 61.4g (0.40mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and control the temperature at 20°C, keep warm for 1.0h, and filter to obtain an intermediate after the reaction is qualified. Then put the intermediate into a reaction bottle containing 300g of solvent, stir and heat to 110°C, cool to 20-25°C after the reaction is qualified, filter and dry to obtain propargyl fluazifop. The yield is 95.8%, the purity is 99.3%, and it is an off-white solid.

[0089] Comparative Example 1

[0090] 20g of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)ketone with a content of 95%, 80mL of methyl isobutyl ketone, 1.15 equivalents of 3,4,5,6-tetrahydrophthalic anhydride, 1.4mL of acetic acid and 1mL of piperidine were put into a reaction bottle, heated and refluxed for 6h, and after the reaction was completed, water was added to azeotropically remove methyl isobutyl ketone, filtered, and slurried with 95% ethanol, and filtered to obtain a crude product of fluazifop-butyl. The crude product was dissolved with acetic acid, and then 95% ethanol was gradually added during heating and reflux to gradually precipitate fluazifop-butyl, and fluazifop-butyl was obtained by filtration and drying, with a yield of 90.3% and a purity of 99.1%.

[0091] Compared with Example 1, Comparative Example 1 uses a high-purity raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3 (4H) ketone. The operation and treatment after the reaction is completed are complicated, requiring precipitation, filtration, and acetic acid / ethanol recrystallization, which increases energy consumption and increases the post-processing process; the actual yield is about 90%. In order to meet the product quality, recrystallization and purification are required, and the yield is mainly lost in the recrystallization mother liquor. The present invention uses a low-purity raw material 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3 (4H) ketone, controls the reaction conditions and then filters and removes impurities, the product loss is small, the post-processing is simple, and the product yield is significantly improved.

[0092] Comparative Example 2

[0093] Add 500g of acetic acid, 100g (0.36mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)-one with a content of 80% to a 1000mL reaction bottle, add 58.6g (0.38mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and heat to 100°C, after the reaction is qualified, cool to 20-25°C, filter and dry to obtain fluazifop-butyl. The yield is 89.3%, the purity is 96.8%, the product color is a reddish brown solid, and recrystallization / slurrying is required to make the product color an off-white solid.

[0094] Comparative Example 3

[0095] Add 500g of acetic acid, 100g (0.36mol) of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H) ketone with a content of 95% to a 1000mL reaction bottle, add 58.6g (0.38mol) of 3,4,5,6-tetrahydrophthalic anhydride in batches, stir and heat to 100°C, after the reaction is qualified, cool to 20-25°C, filter and dry to obtain fluazifop-butyl. The yield is 90.3%, the purity is 97.6%, the product color is a reddish brown solid, and recrystallization / slurrying is required to make the product color an off-white solid.

[0096] The above comparative examples show that the method of directly heating the mixture of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)-one and 3,4,5,6-tetrahydrophthalic anhydride to react, the obtained product has low purity and is a reddish brown solid. Recrystallization / slurrying is required to make the product color an off-white solid, and this process will greatly reduce the reaction yield.

[0097] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A green synthesis process of fluazifop-butyl, comprising the following steps: S1) using 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one and 3,4,5,6-tetrahydrophthalic anhydride as raw materials, performing a first reaction at -20 to 50° C., and filtering to obtain a first solid; S2) subjecting the first solid to a second reaction at 80-120° C. to obtain fluazifop-butyl.

2. The green synthesis process of fluazifop-butyl according to claim 1, characterized in that: The temperature of the first reaction is -10 to 30°C; The temperature of the second reaction is 85-110°C.

3. The green synthesis process of fluazifop-butyl according to claim 1, characterized in that: The solvents for the first reaction and the second reaction are independently selected from one or more of ethers, inert halogenated hydrocarbons, organic acids and aprotic solvents.

4. The green synthesis process of fluazifop-butyl according to claim 3, characterized in that: The inert halogenated hydrocarbon is selected from ethylene dichloride; The organic acid is selected from one or more of formic acid, acetic acid and propionic acid; The aprotic solvent is selected from one or more of DMF, N,N-dimethylacetamide, and methyl isobutyl ketone.

5. The green synthesis process of fluazifop-butyl according to claim 3, characterized in that: The solvents for the first reaction and the second reaction are independently selected from one or more of ethylene dichloride, acetic acid, propionic acid, DMF, and methyl isobutyl ketone.

6. The green synthesis process of fluazifop-butyl according to claim 3, characterized in that: The amount of the solvent used in the first reaction is 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazin-3(4H)one; The amount of solvent used in the second reaction is 2 to 15 times the mass of 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one.

7. The green synthesis process of fluazifop-butyl according to claim 1, characterized in that: The molar ratio of the 6-amino-7-fluoro-4-propynyl-1,4-benzoxazine-3(4H)one to 3,4,5,6-tetrahydrophthalic anhydride is 1:(1-1.5).

8. The green synthesis process of fluazifop-butyl according to claim 1, characterized in that: After the second reaction is completed, the reaction system is cooled to 20-25° C., filtered and dried to obtain fluazifop-butyl.

9. The green synthesis process of fluazifop-butyl according to claim 1, characterized in that: The time of the first reaction is 0.5 to 2 hours.

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