A method for synthesizing triclopyr butoxyethyl ester

Abstract

The application discloses a synthetic method of triclopyr-butoxyethyl ester, and the synthetic method is as follows: alkyl triclopyr ester and ethylene glycol monobutyl ether are used as raw materials, an ionic liquid is used as a catalyst, reaction is carried out at 70-100 DEG C for not less than 2 hours, and triclopyr-butoxyethyl ester is obtained, wherein the ionic liquid is at least one of [MIM-PS][HSO4], [MIM-PS][Cl], [MIM-PS][CF3COO] and [MIM-PS][TsO]. In the application, the triclopyr-butoxyethyl ester is prepared by a solvent-free and ester exchange method, alcohol byproduct is easy to remove, the catalyst can be recovered by water washing, less wastes are produced, and the method is beneficial to industrialization.

Description

Technical Field

[0001] This invention relates to a method for synthesizing organic compounds, and more particularly to a method for synthesizing trichloropyroxyacetic acid butoxyethyl ester. Background Technology

[0002] Triclopyroxyacetic acid butoxyethyl ester (also known as chlorpyrifos butoxyethyl ester), [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid, is a pyridineoxycarboxylic acid herbicide. Its main methods can be divided into three types: dehydration esterification of triclopyroxyacetic acid with ethylene glycol monobutyl ether, transesterification of triclopyroxyacetic acid methyl ester with ethylene glycol monobutyl ether, and etherification of triclopyridine sodium with chloroacetic acid-2-butoxyethyl ester. However, the dehydration esterification method easily produces high-salt wastewater, and the etherification reaction yield is low (Wang Jun et al. "Research on the Synthesis of Triclopyroxyacetic Acid Butoxyethyl Ester." Modern Pesticides 16.4(2017):3). The transesterification method requires heating to reflux temperature, which is demanding. The invention patent application with publication number CN 109180570 A discloses a method for preparing triclopyroxyacetic acid butoxyethyl ester, using ethyl triclopyroxyacetate and ethylene glycol monobutyl ether as raw materials, and tetrabutyl titanate, methanesulfonic acid or toluenesulfonic acid as catalysts, to synthesize triclopyroxyacetic acid butoxyethyl ester by transesterification, but the post-processing is complicated. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a convenient post-processing method for synthesizing trichloropyroxyacetic acid butoxyethyl ester.

[0004] Technical solution: The present invention provides a method for synthesizing triclopyroxyacetic acid butoxyethyl ester, wherein the synthesis method comprises: using triclopyroxyacetic acid alkane ester and ethylene glycol monobutyl ether as raw materials, and an ionic liquid as a catalyst, reacting at 70~100℃ for no less than 2 hours to obtain triclopyroxyacetic acid butoxyethyl ester, wherein the ionic liquid is at least one of [MIM-PS][HSO4], [MIM-PS][Cl], [MIM-PS][CF3COO], and [MIM-PS][TsO].

[0005] Preferably, the triclopyroxyacetic acid alkyl ester is triclopyroxyacetic acid methyl ester or triclopyroxyacetic acid ethyl ester.

[0006] Preferably, the catalyst is added in a proportion of 5-50% based on the weight of triclopyroxyacetic acid alkyl ester.

[0007] Preferably, the catalyst is added at a ratio of 5-20% based on the weight of trichloropyroxyacetic acid alkyl ester. 5% catalyst is sufficient to achieve a reaction yield of over 95%. Increasing the catalyst addition ratio helps to separate the catalyst and reaction raw materials, facilitating catalyst recovery and reuse.

[0008] Preferably, the molar ratio of trichloropyroxyacetic acid alkyl ester to ethylene glycol monobutyl ether is 1:1 to 1:2. More preferably, it is 1:1 to 1:1.2.

[0009] Preferably, the reaction temperature is 70~90℃.

[0010] Preferably, the reaction time is 2 to 5 hours.

[0011] Preferably, the method for preparing the ionic liquid is as follows:

[0012] (1) At room temperature, 1,3-propanesulfonic acid lactone was dissolved in 1,2-dichloroethane, and an equimolar amount of N-methylimidazolium was added dropwise. After the addition was complete, the reaction was allowed to proceed for at least 2 hours to obtain 1-sulfonic acid propyl-3-methylimidazolium [MIM-PS].

[0013] (2) At room temperature, dissolve 1-sulfonic acid propyl-3-methylimidazolium salt [MIM-PS] in water, add an equimolar amount of acid, heat to 90~100℃ and react for no less than 1 hour to obtain an ionic liquid.

[0014] Preferably, in step (2), the acid used is at least one of concentrated hydrochloric acid, trifluoroformic acid, p-toluenesulfonic acid, and concentrated sulfuric acid.

[0015] Preferably, in step (1), the N-methylimidazole is added for at least 30 minutes.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. Simple post-processing: The triclopyroxyacetic acid butoxyethyl ester obtained by solvent-free transesterification method has easy removal of the by-product alcohol, and the catalyst used can be recovered by washing with water, resulting in less waste and facilitating industrialization; 2. Mild reaction conditions and high yield: The reaction temperature is reduced to below 100℃, and the reaction can be completed at 70~90℃, with the yield of the target product reaching more than 95%; 3. High catalytic efficiency: The catalyst can be recycled without any reduction in catalytic activity. Attached Figure Description

[0017] Figure 1 This is a flowchart of the catalyst preparation method according to the first embodiment of the present invention;

[0018] Figure 2 This is a flowchart of the preparation method of triclopyroxyacetic acid butoxyethyl ester according to the present invention;

[0019] Figure 3 This is a liquid chromatogram of a triclopyroxyacetic acid butoxyethyl ester sample prepared by the method of the second embodiment of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0021] Example 1: Preparation of Catalyst

[0022] (1) Weigh 24.42 g (0.2 mol) of 1,3-propanesulfonic acid lactone and dissolve it in 100 mL of 1,2-dichloroethane. Transfer the solution to a 250 mL three-necked flask and add 16.4 g (0.2 mol) of N-methylimidazolium dropwise under vigorous stirring. The addition time should be controlled at more than 30 min. After the addition is complete, allow the solution to rise naturally to room temperature and then continue to stir vigorously for 2 h. The resulting white precipitate is filtered and washed with ether (30 mL × 3). Then, remove the ether under reduced pressure to obtain the product, 40.10 g of 1-propylsulfonic-3-methylimidazolium (MIM-PS), with a yield of 98.2%. Store in a sealed container for later use.

[0023] (2) Weigh 10.21 g (0.05 mol) of MIM-PS and dissolve it in 10 mL of water. Transfer the solution to a 100 mL three-necked flask and add 5.0 g (0.05 mol) of concentrated sulfuric acid dropwise over an ice bath with vigorous stirring for 30 min. After the addition is complete, allow the solution to cool to room temperature and stir for 15 min. Then heat the solution to 100 °C and react for 1 h. After the reaction is complete, remove the water under reduced pressure and wash the solution several times with anhydrous diethyl ether (10 mL × 3). Dry the solution under vacuum at 100 °C for 6 h to obtain 14.5 g of a pale yellow viscous liquid [MIM-PS][HSO4] (MW 302.31), with a yield of 95.9%.

[0024] Following the same synthesis method, the acid used in step (2) was replaced with concentrated HCl, CF3COOH, and p-CH3C6H4SO3H to prepare the corresponding catalysts, which were denoted as [MIM-PS][Cl], [MIM-PS][CF3COO], and [MIM-PS][TsO], respectively.

[0025] Example 2: Synthesis of triclopyroxyacetic acid butoxyethyl ester catalyzed by [MIM-PS][HSO4]

[0026] (1) Add 28.5 g (MW 284.52) of ethyl triclopyroxyethyl, 14.2 g (MW 118.174) of ethylene glycol monobutyl ether, and 5 g of freshly prepared catalyst [MIM-PS][HSO4] (liquid) to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring for 2 h. The reaction was monitored by liquid chromatography. The liquid chromatography conditions were as follows:

[0027]

[0028] (2) Post-processing: After the reaction is complete, continue to heat under reduced pressure to ensure the removal of ethanol. The vacuum degree is 0.01~0.05 MPa. Wash the ethanol-free product with a small amount of water. Allow to stand and separate into layers. The upper layer is an aqueous layer containing the catalyst and the raw material ethylene glycol monobutyl ether. Remove water under reduced pressure and recover the catalyst and ethylene glycol monobutyl ether from the aqueous layer. The lower layer is an ester layer, a pale yellow liquid, mainly composed of crude triclopyroxyacetic acid butoxyethyl ester (MW 356.63). The product content was detected by liquid chromatography and was 99.3%, with a yield of 95.3%.

[0029] Example 3: Synthesis of triclopyroxyacetic acid butoxyethyl ester catalyzed by recovered [MIM-PS][HSO4]

[0030] 28.5 g of ethyl trichloropyroxyethyl acetate, 14.2 g of ethylene glycol monobutyl ether, and the catalyst [MIM-PS][HSO4] (liquid) recovered in Example 2, along with a small amount of ethylene glycol monobutyl ether, were added to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring. After 2 h of reaction, the product was post-treated as in Example 1 to obtain a pale yellow crude product of trichloroacetic acid butoxyethyl ester. The content of the product was determined by liquid chromatography, and the content was 98.7%, with a yield of 96.5%.

[0031] Example 4: Synthesis of triclopyroxyacetic acid butoxyethyl ester catalyzed by recovered [MIM-PS][HSO4]

[0032] 28.5 g of ethyl trichloropyroxyethyl acetate, 23.6 g of ethylene glycol monobutyl ether, and the recovered catalyst [MIM-PS][HSO4] (liquid) from Example 3 were added to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring. After 2 h of reaction, the product was post-treated in the same way as in Example 1 to obtain a pale yellow crude product of trichloroacetic acid butoxyethyl ester. The content of the product was determined by liquid chromatography and was 98.15%, with a yield of 97.4%.

[0033] Example 5: Synthesis of triclopyroxyacetic acid butoxyethyl ester

[0034] 28.5 g of ethyl trichloropyroxyethyl acetate, 14.2 g of ethylene glycol monobutyl ether, and 10 g of catalyst [MIM-PS][Cl] (liquid) were added to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring. After 2 h of reaction, the product was post-treated in the same way as in Example 1 to obtain a pale yellow crude product of trichloroacetic acid butoxyethyl ester. The content of the product was detected by liquid chromatography and the content was 98.95%, with a yield of 96.5%.

[0035] Example 6: Synthesis of triclopyroxyacetic acid butoxyethyl ester

[0036] 28.5 g of ethyl triclopyroxyacetate, 14.2 g of ethylene glycol monobutyl ether, and 10 g of [MIM-PS][CF3COO] catalyst were added to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring. After 2 h of reaction, the product was washed with water and the solvent layer was removed under reduced pressure to obtain a pale yellow crude product of ethyl triclopyroxyacetate butoxyethyl ester. The content of the product was determined by liquid chromatography and the content was 99.15%, with a yield of 95.8%.

[0037] Example 7: Synthesis of triclopyroxyacetic acid butoxyethyl ester

[0038] 27.0 g of methyl trichloropyroxyacetate, 14.2 g of ethylene glycol monobutyl ether, and 10 g of [MIM-PS][TsO] (liquid) were added to a 500 mL single-necked flask. Esterification was carried out at 90 °C with stirring. After 2 h of reaction, the product was washed with water and methanol was removed from the solvent layer under reduced pressure to obtain a pale yellow crude product of trichloroacetic acid butoxyethyl ester. The content of the product was determined by liquid chromatography and was 99.05%, with a yield of 96.2%.

[0039] Example 8: 27.0 g of methyl trichloropyroxyacetate, 14.2 g of ethylene glycol monobutyl ether, and 10 g of the catalyst [MIM-PS][TsO] (liquid) recovered in Example 7 were added to a 500 mL single-necked flask. Esterification was carried out at 80 °C with stirring. After 2 h of reaction, the product was washed with water and methanol was removed from the solvent layer under reduced pressure to obtain a pale yellow crude product of trichloroacetic acid butoxyethyl ester. The content of the product was detected by liquid chromatography and the content was 99.18%, with a yield of 95.9%.

[0040] The esterification reaction used in this invention employs an ionic liquid catalyst (liquid) as the catalyst, which can be recycled multiple times, reducing wastewater generation. The product yield is high and the content of impurity butyl ether is low, greatly improving its economic efficiency and environmental friendliness, and it can be widely used in industrial production.

Claims

1. A method for synthesizing triclopyroxyacetic acid butoxyethyl ester, characterized in that, The synthesis method is as follows: using triclopyroxyacetic acid alkyl ester and ethylene glycol monobutyl ether as raw materials, and an ionic liquid as a catalyst, the reaction is carried out at 70~90℃ for 2~5 hours to obtain triclopyroxyacetic acid butoxyethyl ester. The ionic liquid is at least one of [MIM-PS][HSO4], [MIM-PS][Cl], [MIM-PS][CF3COO], and [MIM-PS][TsO]. The molar ratio of triclopyroxyacetic acid alkyl ester and ethylene glycol monobutyl ether is 1:1~1:

2.

2. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that, The trichloropyroxyacetic acid alkyl ester is methyl trichloropyroxyacetic acid or ethyl trichloropyroxyacetic acid.

3. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that, The catalyst is added in a proportion of 5-50% based on the weight of triclopyroxyacetic acid alkyl ester.

4. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that, The catalyst is added at a rate of 5-20% based on the weight of triclopyroxyacetic acid alkyl ester.

5. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that, The molar ratio of the trichloropyroxyacetic acid alkyl ester and ethylene glycol monobutyl ether is 1:1 to 1:1.

2.

6. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that, The preparation method of the ionic liquid is as follows: (1) At room temperature, 1,3-propanesulfonic acid lactone was dissolved in 1,2-dichloroethane, and an equimolar amount of [unspecified substance] was added dropwise. N After the addition of 1-methylimidazole is complete, the reaction time shall be no less than 2 hours to obtain 1-sulfopropyl-3-methylimidazole inner salt [MIM-PS]. (2) At room temperature, 1-sulfonic acid propionyl-3-methylimidazolium salt [MIM-PS] is dissolved in water, an equimolar amount of acid is added, and the temperature is raised to 90~100℃ and reacted for no less than 1 hour to obtain an ionic liquid. The acid is at least one of concentrated hydrochloric acid, trifluoroformic acid, p-toluenesulfonic acid, and concentrated sulfuric acid.

7. The method for synthesizing trichloropyroxyacetic acid butoxyethyl ester according to claim 6, characterized in that, In step (1), N The dripping time for methylimidazole should be no less than 30 minutes.

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