Method for recovering difenoconazole from high-boiling substances

Abstract

The application is suitable for the technical field of pesticide preparation, and provides a method for recovering difenoconazole from high-boiling substances, comprising the following steps: (1) after difenoconazole high-boiling substances are dissolved by being warmed with an organic solvent, cooling to room temperature, filtering, adding acid for 3 to 5 times at a temperature below 30 DEG C, performing suction filtration after each time of adding acid, combining the obtained solid, washing with an organic solvent, and drying; (2) mixing the dried solid in step (1) with an organic solvent and water, adding liquid alkali while stirring, extracting and separating the water layer to obtain an organic material layer; (3) adding water to the organic material layer in step (2) and stirring, then simultaneously adding acid and an oxidizing agent dropwise, and standing to separate layers; (4) extracting the water layer after standing to separate layers in step (3) with an organic solvent for 3 times, combining the organic material layer, and removing the organic solvent under reduced pressure to obtain difenoconazole oil paste.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pesticide preparation, and provides a method for recovering difenoconazole from high-boiling substances. BACKGROUND

[0002] Difenoconazole is a low-toxicity heterocyclic fungicide, is easily soluble in organic solvents, has small mobility in soil, and is slowly degraded. Difenoconazole belongs to triazole fungicides, is a sterol demethylation inhibitor, has the characteristics of high efficiency, broad spectrum, low toxicity, and low dosage, is an excellent variety of triazole fungicides, has extremely strong systemicity, inhibits the biosynthesis of ergosterol in pathogen cells, thereby destroying the structure and function of pathogen cell membranes, and has good protection and treatment effects on various fungal diseases of vegetables, melons and fruits, and is an ideal fungicide for preventing and treating crop resistant diseases such as citrus scab and spot and leaf fall diseases in China and even the world.

[0003] In the production process of difenoconazole, most production processes will produce low-content difenoconazole oil paste or high-boiling substances, such as high-boiling substances produced by high-vacuum molecular distillation process or salting process. The content of difenoconazole in these high-boiling substances is about 5% to 15%, and even higher, even 20%. The difenoconazole cannot be recovered by normal distillation, recrystallization, extraction and other means, and is disposed as hazardous waste. This is not only not conducive to environmental protection and clean production, but also causes waste of products and reduces product yield, indirectly increasing product cost. SUMMARY

[0004] The application aims to provide a method for recovering difenoconazole from high-boiling substances, which has the advantage of reducing the generation of hazardous waste.

[0005] In order to achieve the above-mentioned purpose, the application provides a method for recovering difenoconazole from high-boiling substances, which comprises the following steps:

[0006] (1) The difenoconazole high-boiling substance is dissolved by heating with an organic solvent, then cooled to room temperature, filtered, and then acid is added for 3 to 5 times at a temperature below 30℃. After each addition of acid, the filtrate is obtained by suction filtration, and then the obtained solid is combined, washed with an organic solvent, and dried;

[0007] (2) The dried solid in step (1) is mixed with an organic solvent and water, and then liquid alkali is added dropwise while stirring, and then the water layer is separated by extraction to obtain an organic layer;

[0008] (3) The organic layer in step (2) is stirred with water, and then acid and an oxidizing agent are added dropwise at the same time, and then the layers are separated after standing;

[0009] (4) The water layer after standing in step (3) is extracted with an organic solvent for 3 times, and then the organic layer is combined, and then the organic solvent is removed under reduced pressure to obtain difenoconazole oil paste.

[0010] The double drop in step (3) needs to be synchronized, the oxidizing property of the oxidizing agent in the acidic environment is maintained, and the acidity in the whole reaction process can be ensured not to be too strong.

[0011] Further, the acid in step (1) and step (3) is one of trifluoroacetic acid, trifluoromethanesulfonic acid, 68% concentrated nitric acid, 60% concentrated sulfuric acid or 30% hydrochloric acid.

[0012] Further, the organic solvent in step (1) to step (4) is one of toluene, xylene, dichloromethane.

[0013] Further, the oxidizing agent in step (3) is one of hydrogen peroxide, peroxyacetic acid, sodium percarbonate, ammonium persulfate, sodium hypochlorite.

[0014] Further, the liquid alkali in step (2) is one of aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous lithium hydroxide.

[0015] Further, the mass ratio of the acid to the high-boiling distillate of dimethomorph in step (1) is 0.3-0.4:1.

[0016] Further, the temperature of the acid drop in step (1) is preferably 20-30℃.

[0017] Further, the mass ratio of the high-boiling distillate of dimethomorph to the solvent in step (1) is 1:2.9-4.5.

[0018] The purpose of the present application is to provide a method for recovering dimethomorph in high-boiling distillate, which has the following beneficial effects:

[0019] ①The present application uses low-content dimethomorph high-boiling distillate as raw material, and recovers part of the dimethomorph product through a series of treatment methods, which can greatly reduce the generation of hazardous waste and is conducive to clean production.

[0020] ②The recovery method of the present application can be applied to industry, and part of the product can be recovered from hazardous waste to improve the overall yield of the product. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. The materials, reagents and the like used in the following examples, if not specifically stated, can be obtained from commercial channels.

[0022] Example 1:

[0023] Into a four-necked flask, add difenoconazole high-boiling residue 300 g and toluene 1200 ml, heat to dissolve, then cool to room temperature, filter, slowly add trifluoroacetic acid dropwise at a temperature of 30°C, 5 times, 20 g each time, a total of 100 g, solid slowly precipitates during the dropwise addition. After the first dropwise addition is complete, keep at 30°C, filter the solid, then perform the second dropwise addition, filter the solid after the second dropwise addition, repeat this process 5 times, basically no solid precipitates, at this time, the organic layer is concentrated under reduced pressure to remove the solvent, the residue is disposed of as hazardous waste. The filtered solids are combined, washed with toluene, and dried to obtain a total of 45 g of gray or off-white solid.

[0024] Put the obtained gray or off-white solid into a new four-necked flask, add toluene 300 ml, water 100 g, and dropwise add an aqueous solution of lithium hydroxide with stirring, adjust the pH to 5, the turbid solution gradually clarifies and separates into layers, separate the water layer, and obtain the upper layer as the organic layer. Take the organic layer, add water 100 g, and stir at room temperature, then double-dropwise add trifluoroacetic acid 10 g and hydrogen peroxide 5 g, the double-dropwise addition must be performed synchronously. After the double-dropwise addition is complete, stand and separate into layers, the water layer is repeatedly extracted with 100 ml of toluene 3 times, the combined organic layer is concentrated under reduced pressure to remove the organic solvent, and difenoconazole oil paste 42.6 g is obtained, the difenoconazole content is 92.7%, and the yield is 87.7%.

[0025] Example 2:

[0026] Into a four-necked flask, add difenoconazole high-boiling residue 300 g and toluene 1200 ml, heat to dissolve, then cool to room temperature, filter, slowly add trifluoroacetic acid dropwise at a temperature of 30°C, 5 times, 20 g each time, a total of 100 g, solid slowly precipitates during the dropwise addition. After the first dropwise addition is complete, keep at 30°C, filter the solid, then perform the second dropwise addition, filter the solid after the second dropwise addition, repeat this process 5 times, basically no solid precipitates, at this time, the organic layer is concentrated under reduced pressure to remove the solvent, the residue is disposed of as hazardous waste. The filtered solids are combined, washed with toluene, and dried to obtain a total of 45 g of gray or off-white solid.

[0027] Put the obtained gray or off-white solid into a new four-necked flask, add toluene 300 ml, water 100 g, and dropwise add an aqueous solution of lithium hydroxide with stirring, adjust the pH to 5, the turbid solution gradually clarifies and separates into layers, separate the water layer, and obtain the upper layer as the organic layer. Take the organic layer, add water 100 g, and stir at room temperature, then double-dropwise add trifluoroacetic acid 10 g and hydrogen peroxide 5 g, the double-dropwise addition must be performed synchronously. After the double-dropwise addition is complete, stand and separate into layers, the water layer is repeatedly extracted with 100 ml of toluene 3 times, the combined organic layer is concentrated under reduced pressure to remove the organic solvent, and difenoconazole oil paste 42.6 g is obtained, the difenoconazole content is 92.7%, and the yield is 87.7%.

[0028] Example 3:

[0029] Into a four-necked flask, add difenoconazole high-boiling residue 300 g and dichloromethane 1000 ml, dissolve at elevated temperature, then cool to room temperature, filter, slowly drop 68% concentrated nitric acid at 25℃, drop 30 g each time for 3 times, 90 g in total, solid slowly precipitates during the dropping process. After the first drop, keep at 25℃, filter the solid, then drop again, filter the solid after the second drop, repeat 3 times, basically no solid precipitates, at this time, the organic layer is concentrated under reduced pressure to remove the solvent, and the residue is treated as hazardous waste. The filtered solid is combined and washed with toluene to obtain 36.9 g of gray or off-white solid.

[0030] Put the obtained gray or off-white solid into a new four-necked flask, add dichloromethane 300 ml, water 100 g, drop the aqueous solution of sodium hydroxide under stirring, adjust the pH to 6, the turbid solution gradually clarifies and separates into layers, separate the water layer, and obtain the organic layer. Take the organic layer, add water 100 g and stir at room temperature, then double-drop 13 g of 68% concentrated nitric acid and 5 g of sodium percarbonate, the double-dropping must be carried out synchronously. After the double-dropping is completed, stand and separate into layers, the water layer is repeatedly extracted with 100 ml of dichloromethane for 3 times, the combined organic layer is concentrated under reduced pressure to remove the organic solvent, and difenoconazole oil paste 35.2 g is obtained, the difenoconazole content is 93.7%, and the yield is 89.3%.

[0031] Example 4:

[0032] Into a four-necked flask, add difenoconazole high-boiling residue 300 g and toluene 1200 ml, dissolve at elevated temperature, then cool to room temperature, filter, slowly drop 60% concentrated sulfuric acid at 30℃, drop 24 g each time for 5 times, 120 g in total, solid slowly precipitates during the dropping process. After the first drop, keep at 30℃, filter the solid, then drop again, filter the solid after the second drop, repeat 5 times, basically no solid precipitates, at this time, the organic layer is concentrated under reduced pressure to remove the solvent, and the residue is treated as hazardous waste. The filtered solid is combined and washed with toluene to obtain 27.6 g of gray or off-white solid.

[0033] The obtained gray or off-white solid was placed into a new four-necked flask, 300 ml of toluene and 100 g of water were added, and a sodium hydroxide aqueous solution was added dropwise under stirring until the pH was adjusted to 7. The turbid solution was gradually clarified and separated into layers, and the water layer was separated to obtain the upper organic layer. The organic layer was added with 100 g of water and stirred at room temperature, and then 15 g of 60% concentrated sulfuric acid and 5 g of ammonium persulfate were added dropwise simultaneously. After the double dropwise addition was completed, the solution was allowed to stand and separate into layers, and the water layer was repeatedly extracted with 100 ml of organic solvent for 3 times. The organic layers were combined and concentrated under reduced pressure to remove the organic solvent, to obtain 25.7 g of difenoconazole oil paste with a difenoconazole content of 92.7% and a yield of 86.3%.

[0034] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the claims attached to the present application.

Claims

1. A process for recovery of difenoconazole from a high boiler, characterized by, The content of difenoconazole in the difenoconazole high-boiling residue is 5% to 20%, and the method comprises the following steps: (1) The difenoconazole high-boiling residue is dissolved in an organic solvent at a high temperature, and then cooled to room temperature. The acid is added in 3 to 5 times at a temperature below 30℃, and the solid obtained by filtration is combined, washed with an organic solvent, and dried; (2) The dried solid in step (1) is mixed with an organic solvent and water, and liquid alkali is added dropwise while stirring. The water layer is separated by extraction to obtain an organic layer; (3) The organic layer in step (2) is stirred with water, and then acid and oxidant are added dropwise at the same time. The layers are separated after standing; (4) The water layer obtained after standing in step (3) is extracted with an organic solvent for 3 times, and then the organic layer is combined. The organic solvent is removed under reduced pressure to obtain difenoconazole oil paste.

2. The process for recovery of difenoconazole from high boilers as claimed in claim 1 wherein, The acid in step (1) and step (3) is one of trifluoroacetic acid, trifluoromethanesulfonic acid, 68% concentrated nitric acid, 60% concentrated sulfuric acid, or 30% hydrochloric acid.

3. The process for recovery of difenoconazole from high boilers as claimed in claim 2 wherein, The organic solvent in step (1) to step (4) is one of toluene, xylene, dichloromethane.

4. The process for recovery of difenoconazole from high boiler according to claim 3, wherein, The oxidant in step (3) is one of hydrogen peroxide, peroxyacetic acid, sodium percarbonate, ammonium persulfate, and sodium hypochlorite.

5. The process for recovery of difenoconazole from high boiler according to claim 3, wherein, The liquid alkali in step (2) is one of aqueous sodium hydroxide, aqueous potassium hydroxide, and aqueous lithium hydroxide.

6. The process for recovery of difenoconazole from high boiler according to claim 3, wherein, The mass ratio of the acid to the difenoconazole high-boiling residue in step (1) is 0.3 to 0.4:

1.

7. The process for recovery of difenoconazole from high boiler according to claim 3, wherein, The temperature for adding the acid in step (1) is 20 to 30℃.

8. The process for recovery of difenoconazole from high boiler according to claim 3, wherein, The mass ratio of the difenoconazole high-boiling residue to the solvent in step (1) is 1:2.9 to 4.5.