A method for preparing 3,4'-dichlorodiphenyl ether by using difenoconazole waste

Abstract

The present application relates to a kind of methods for preparing 3,4'-dichlorodiphenyl ether using difenoconazole waste, with waste containing difenoconazole, difenoconazole triazole isomer and difenoconazole triazole ortho isomer as raw material, after hydrolysis ring opening, then reaction with base, 3,4'-dichlorodiphenyl ether crude product is obtained, after distillation, 3,4'-dichlorodiphenyl ether finished product is obtained.The content of 3,4'-dichlorodiphenyl ether obtained by the present application is not less than 99.1%, the effective recycling of existing preparation difenoconazole generated waste mother liquor is realized, both environmental benefits, and economic benefits are generated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical synthesis. More particularly, the present application relates to a method for preparing 3,4'-dichlorodiphenyl ether from difenoconazole waste. BACKGROUND

[0002] Difenoconazole, also known as oxadixyl, and commercially known as "Shigao", is a triazole fungicide, a sterol demethylation inhibitor, and has the characteristics of high efficiency, broad spectrum, low toxicity, and low dosage. It is an ideal fungicide for preventing and treating crop diseases such as citrus scab and spot and leaf fall diseases, and has become a star product that pesticide production enterprises at home and abroad are competing to develop.

[0003] In the prior art, in the synthesis of difenoconazole, the main product 1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (difenoconazole, denoted as compound I) accounts for 75%-80%, and at the same time, 12-15% of 4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-4H-[1,2,4]triazole (denoted as compound II) and 1-3% of 1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (denoted as compound III) are inevitably produced, and the structural formulae are as follows:

[0004]

[0005] The prior art usually separates and purifies difenoconazole by distillation or salting method. However, since the boiling point of difenoconazole is high, the distillation temperature needs to be higher than 260℃ and the vacuum requirement is very high, the conditions are very harsh, the safety hidden danger is high, and the product is easy to decompose into impurities under high temperature conditions, causing the yield to be reduced, so the implementation is difficult. The salting separation method usually adopts nitric acid salting method, and the salting mother liquor is extracted and then salified to extract difenoconazole, and the secondary salting mother liquor mainly includes three components, which are the aforementioned compound I (difenoconazole), compound II and compound III. Due to the influence of the other two components, it is difficult to separate and extract difenoconazole from the mother liquor. At present, there is no resource utilization method for this secondary salting mother liquor in China, and it can only be treated as hazardous waste, which not only has high treatment cost, but also is not conducive to environmental protection, and resources are wasted.

[0006] Therefore, a new technical solution is needed to solve the problem of recycling the mother liquor containing difenoconazole, compound II and compound III. SUMMARY

[0007] The application aims to provide a recycling method of difenoconazole waste.

[0008] The principle of the application is that difenoconazole (compound I), 4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-4H-[1,2,4]triazole (compound II) and 1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (compound III) can be hydrolyzed to generate 1-[2-chloro-4-(4-chlorophenoxy)-phenyl-2-[1,2,4]triazol-1-yl-ethanone (intermediate I), 1-[2-chloro-4-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-4-yl-ethanone (intermediate II) and 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-1-yl-ethanone (intermediate III), and then undergo alkaline hydrolysis in the presence of a base to prepare 3,4'-dichlorodiphenyl ether.

[0009] Based on this, the application provides a method for preparing 3,4'-dichlorodiphenyl ether from difenoconazole waste, which comprises the following steps:

[0010] (1) adding 10-32% hydrochloric acid by mass concentration and difenoconazole waste in a reaction bottle, and reacting at 84-108°C to generate an intermediate mixture, and then filtering the obtained mixture to obtain an intermediate product A containing water;

[0011] (2) adding solvent A and the intermediate product A containing water in a reaction bottle, and dehydrating by heating and refluxing until the water content is qualified, and then cooling to obtain a mixture of anhydrous intermediate product A and solvent A;

[0012] (3) adding solvent B and a base in a reaction bottle, heating and maintaining at 100-140°C, and adding the mixture of anhydrous intermediate product A and solvent A dropwise, and then washing the reaction system with water and removing the solvent to obtain a crude 3,4'-dichlorodiphenyl ether.

[0013] In the present application, the waste liquid used in step (1) is produced by the salt separation method in the prior art for preparing difenoconazole, and mainly contains three components, namely 1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (Compound I, i.e. difenoconazole), 4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-4H-[1,2,4]triazole (Compound II), and 1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (Compound III), and their chemical structural formulas are as follows:

[0014]

[0015] Specifically, in step (1), the reaction equation is as follows:

[0016]

[0017] The other reaction raw materials used in the present application are all the products commonly sold in the market.

[0018] According to a preferred embodiment of the present application, the concentration of hydrochloric acid in step (1) is 10-32%. In the present application, if the concentration of hydrochloric acid is lower than 10%, the reaction can still occur, but the reaction speed is very slow; if the concentration of hydrochloric acid is higher than 32%, the boiling point of hydrochloric acid is too low to reach the required temperature for the reaction, and the reaction can still occur, but the reaction speed is also very slow, and it is not economical to have a low or high concentration of hydrochloric acid.

[0019] According to a preferred embodiment of the present application, the temperature rising reflux dehydration in step (2) is carried out under normal pressure, and the moisture content in the intermediate product B is considered to be qualified when it is ≤0.1%.

[0020] According to a preferred embodiment of the present application, the solvent in step (2) is one or both of toluene and xylene.

[0021] According to a preferred embodiment of the present application, in step (2), the weight ratio of the intermediate product A to the solvent A is 1:1-5. In the present application, if the weight ratio of the intermediate product A to the solvent A is greater than 1:1, the dehydration efficiency will be reduced; and if it is less than 1:5, too much solvent is used, which increases the energy consumption and affects the production capacity.

[0022] In step (3), the reaction equation is as follows:

[0023]

[0024] Preferably, the base can be sodium hydroxide, potassium hydroxide or a mixture thereof, and the solvent B can be toluene, xylene, methanol, ethanol or a mixture thereof.

[0025] In step (3), the weight ratio of the base to the difenoconazole waste in step (1) is 0.5-1:1. In the present application, if the weight ratio of the base to the difenoconazole waste is less than 0.5:1, the reaction impurities are high and the yield is low; if the weight ratio of the base to the difenoconazole waste is greater than 1:1, the reaction can also occur, but the base is excessive and not economical.

[0026] According to a preferred embodiment of the present application, the weight ratio of the solvent in step (3) to the difenoconazole waste in step (1) is 2-5:1. In the present application, if the weight ratio of the solvent to the difenoconazole waste is less than 2:1, the reaction impurities are high and the yield is low; if the weight ratio of the solvent to the difenoconazole waste is greater than 5:1, the solvent is excessive and not economical.

[0027] According to a preferred embodiment, the reaction temperature in step (3) is 100-140℃, and if the temperature is lower than 100℃, the reaction is slow although it can also occur.

[0028] After obtaining the 3,4'-dichlorodiphenyl ether crude product in step (3), the 3,4'-dichlorodiphenyl ether finished product can be further obtained under the condition of reduced pressure distillation at 146℃ / 5mmHg, and the distillation operation can refer to Chinese Invention Patent Application CN 101423460A.

[0029] Based on this, the present application further provides a compound 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-1-yl-ethanone, which has the following chemical structural formula:

[0030]

[0031] The preparation method of the compound 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-1-yl-ethanone is to add 10-32% hydrochloric acid by mass concentration and 1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4]triazole (compound III) in a reaction bottle, and react at 84-108℃ to generate an open ring intermediate, and after cooling, filtration and purification, the open ring intermediate is obtained.

[0032] The application prepares 3,4'-dichlorodiphenyl ether through ring-opening, dehydration, alkaline hydrolysis and other steps from the waste mother liquor produced by the salt separation method in the prior art to prepare difenoconazole. The method changes waste into treasure of difenoconazole waste, realizes effective recycling of the waste mother liquor, and produces environmental protection benefits and economic benefits.

[0033] The beneficial effects of the application are:

[0034] (1) The recycling method of the difenoconazole waste solves the common problems in the industry.

[0035] (2) The raw materials are easy to obtain, the reaction steps are few, the process is simple, and the production cost is low.

[0036] (3) The difenoconazole waste is converted into 3,4'-dichlorodiphenyl ether, which changes waste into treasure and recycling, not only solves the environmental pollution problem, but also increases economic benefits and enhances the core competitiveness of enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the liquid chromatogram of the raw material difenoconazole waste used in the application;

[0038] Figure 2 is the liquid chromatogram of the 3,4'-dichlorodiphenyl ether product prepared by the application;

[0039] Figure 3 is the nuclear magnetic hydrogen spectrum of 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazole-1-yl-ethanone prepared by the application. DETAILED DESCRIPTION

[0040] The following examples are used to non-limitingly explain the technical solutions of the application.

[0041] In the application, unless otherwise specified, the "%" used to explain the concentration is the weight percentage.

[0042] In the application, the analysis conditions of liquid chromatography are as follows: Tnature C18, 5 μm, 4.6*150 mm chromatographic column, mobile phase is methanol:0.5% phosphoric acid aqueous solution=80:20(mass ratio), flow rate is 1ml / min, wavelength is 230nm.

[0043] The HPLC content data in the application are all area normalization contents.

[0044] Example 1

[0045] The waste produced by the salt separation method in the prior art for preparing difenoconazole is used as raw material. The waste is a black oily liquid. The main components in the mother liquor are confirmed by liquid chromatography as follows:

[0046] 1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H- [1,2,4] triazole, content 58%; 4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl- [1,3] dioxolan-2-ylmethyl}-4H-[1,2,4] triazole, content 21.3%; 1-{2-[4-chloro-2-(4- chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4] triazole, content 15.5%, as shown in Figure 1 .

[0047] Step (1): In a 500 ml reaction bottle, 250 grams of 20% mass concentration hydrochloric acid and 100 grams of difenoconazole waste are put in, and the temperature is raised to 108°C. After 6 hours of incubation, the contents of difenoconazole (compound I), difenoconazole triazole isomer (4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-4H- [1,2,4] triazole, i.e. compound II) and difenoconazole triazole ortho isomer (1-{2-[4-chloro-2-(4- chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolan-2-ylmethyl}-1H-[1,2,4] triazole, i.e. compound III) are less than 0.5%, the reaction is qualified, the temperature is lowered to 25°C, and 105 grams of intermediate product A containing water are obtained after filtration.

[0048] Step (2): In a 500 ml reaction bottle, 250 grams of xylene are added, and 105 grams of intermediate product A containing water obtained in step (1) are put in. The stirring is started, the temperature is raised to reflux for 4 hours, and when there is no water distillation in the water trap, the sample analysis of the material in the reaction bottle confirms that the water content is less than 0.1%, indicating that the reaction is qualified. The temperature is lowered to 100°C, and a mixture of anhydrous intermediate product A and xylene is obtained, which is ready for use.

[0049] Step (3): In a 1000ml reaction flask, add 200g xylene and 10g methanol, add 60g potassium hydroxide, heat to 110℃, stir for half an hour, add the prepared materials from step (2) dropwise, control the temperature at 110-120℃, and continue to keep warm for 2 hours after the addition is complete. Take a sample to analyze the content of intermediate product A (including intermediate I, intermediate II and intermediate III) mixture. The sum of the contents is less than 0.5%, indicating that the reaction is qualified. Cool down to 30-40℃. Then add 200g water dropwise. After the addition is complete, stir for half an hour, let stand and separate into layers. The upper layer is the xylene layer. After distilling off the xylene, further distill under reduced pressure at 146℃ / 5mmHg to obtain 48g of 3,4′-dichlorodiphenyl ether product. HPLC verification confirmed that it is 3,4′-dichlorodiphenyl ether, and the content is 99.2% after area normalization content analysis. The results are as follows. Figure 2 As shown.

[0050] Example 2

[0051] The procedure is the same as in Example 1, except that:

[0052] Step (1): In a 1000ml reaction flask, add 500g of 10% hydrochloric acid and 100g of difenoconazole waste. Heat to 103℃ and maintain the reaction temperature for 13 hours. Then, take samples to analyze difenoconazole (compound I) and difenoconazole triazole isomer (4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-4 The sum of the contents of H-[1,2,4]triazole (i.e., compound II) and the ortho-isomer of phenoxymethyltriazole (1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole (i.e., compound III) was less than 0.5%, the reaction was qualified, the temperature was lowered to 25°C, and after filtration, 104 g of aqueous intermediate product A was obtained.

[0053] Step (2): Add 400g of toluene to a 500ml reaction flask, add 104g of the aqueous intermediate product A obtained in step (1), start stirring, heat and reflux to dehydrate for 4 hours, wait until no water is distilled out in the water separator, take a sample to analyze the moisture content of the material in the reaction flask is less than 0.1%, the reaction is qualified, cool down to 100℃, and obtain a mixture of anhydrous intermediate product A and toluene for later use.

[0054] In step (3), 500 g of toluene and 55 g of sodium hydroxide were added to a 2000 ml reaction flask. The temperature was raised to 100 °C and stirred for half an hour. The prepared materials from step (2) were added dropwise, and the temperature was controlled at 100-110 °C. After the addition was completed, the temperature was maintained for 4 hours. The sample analysis showed that the sum of the contents of intermediate product A (including intermediate I, intermediate II and intermediate III) was less than 0.5%, indicating that the reaction was qualified. The temperature was lowered to 30-40 °C, and 200 g of water was added dropwise. After the addition was completed, the mixture was stirred for half an hour and allowed to stand for separation. The upper toluene layer was distilled to remove toluene, and then further distilled under reduced pressure at 146 °C / 5 mmHg to obtain 38 g of 3,4′-dichlorodiphenyl ether product. The content was 99.1% according to the area normalization content analysis.

[0055] Example 3

[0056] The procedure is the same as in Example 1, except that:

[0057] Step (1): In a 500ml reaction flask, add 155g of 32% hydrochloric acid and 100g of difenoconazole waste. Heat to 84℃ and maintain the reaction temperature for 16 hours. Then, take samples to analyze difenoconazole (compound I) and difenoconazole triazole isomer (4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-4H- The sum of the contents of [1,2,4]triazole (i.e., compound II) and the ortho-isomer of phenoxytetracyclazole (1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole (i.e., compound III) was less than 0.5% of the total weight, indicating that the reaction was satisfactory. The mixture was cooled to 25°C and filtered to obtain 106 g of aqueous intermediate A.

[0058] Step (2): Add 110 g of xylene to a 500 ml reaction flask, add 106 g of aqueous intermediate product A obtained in step (1), start stirring, heat and reflux to dehydrate for 8 hours, wait until no water is distilled out in the water separator, take a sample to analyze the moisture content of the material in the reaction flask is less than 0.1%, the reaction is qualified, cool down to 100℃, and obtain a mixture of anhydrous intermediate product A and xylene for later use.

[0059] Step (3): In a 2000ml reaction flask, add 300g xylene and 95g potassium hydroxide, heat to 130℃, stir for half an hour, add the prepared materials from step (2) dropwise, control the temperature at 130-140℃, and after the addition is complete, continue to keep warm for 1.5 hours. Take a sample to analyze the content of intermediate product A (including intermediate I, intermediate II and intermediate III) and find that the sum of the contents is less than 0.5%, the reaction is qualified, cool down to 30-40℃, add 300g water dropwise, stir for half an hour after the addition is complete, let stand to separate the layers, and after distilling off the xylene from the separated upper xylene layer, further distill under reduced pressure at 146℃ / 5mmHg to obtain 45g of 3,4′-dichlorodiphenyl ether product with an analytical content of 99.4%.

[0060] Example 4

[0061] The procedure is the same as in Example 1, except that:

[0062] Step (1): In a 500ml reaction flask, add 165g of 30% hydrochloric acid and 100g of difenoconazole waste. Heat to 90℃ and keep the reaction at this temperature for 11 hours. Take a sample for analysis. The sum of the contents of difenoconazole (compound I), difenoconazole triazole isomer (4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-4H-[1,2,4]triazole, i.e., compound II) and difenoconazole triazole ortho-isomer (1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole, i.e. compound III) is less than 0.5%. The reaction is qualified. Cool down to 25℃ and filter to obtain 105g of aqueous intermediate product A.

[0063] Step (2): Add 110 g of xylene to a 500 ml reaction flask, add 105 g of aqueous intermediate product A obtained in step (1), start stirring, heat and reflux for 6 hours to dehydrate, wait until no water is distilled out in the water separator, take a sample to analyze the moisture content of the material in the reaction flask is less than 0.1%, the reaction is qualified, cool down to 100℃, and obtain a mixture of anhydrous intermediate product A and xylene for later use.

[0064] Step (3): In a 2000ml reaction flask, add 300g xylene, 15g ethanol, and 60g potassium hydroxide. Heat to 113℃ and stir for half an hour. Add the prepared materials from step (2) dropwise, keeping the temperature at 110-120℃. After the addition is complete, continue to keep warm for 1.5 hours. Take a sample to analyze the content of intermediate product A (including intermediate I, intermediate II, and intermediate III) and find that the sum of the contents is less than 0.5%. The reaction is qualified. Cool down to 30-40℃ and add 300g water dropwise. After the addition is complete, stir for half an hour and let it stand to separate into layers. After distilling off the xylene from the separated upper xylene layer, further distill under reduced pressure at 146℃ / 5mmHg to obtain 45g of 3,4′-dichlorodiphenyl ether product with an analytical content of 99.4%.

[0065] Example 5

[0066] In a 500 ml reaction flask, 250 g of 19% hydrochloric acid and 100 g of the ortho-isomer of difenoconazole triazole (1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole, i.e., compound III) were added. The mixture was heated to 107 °C and reacted for 8 hours. After sampling and analysis, the content of compound III was found to be less than 0.5%, indicating that the reaction was successful. The reaction system was cooled to 25 °C, filtered, and 103 g of aqueous intermediate III was obtained. 150 g of ethanol was added, and the mixture was heated to 80 °C. After stirring for half an hour, the mixture was cooled to 5 °C, filtered, and dried to obtain 68 g of intermediate III.

[0067] The obtained intermediate III was confirmed by 1H NMR spectroscopy to be 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-1-yl-ethyl ketone, as shown below. Figure 3 As shown: 1 H NMR (400MHz, CDCl3): δ = 8.18 (s, 1H), 7.99 (s, 1H), 7.96 (d, J = 8.4Hz, 1H), 7.45 (d, J = 8.8Hz, 2H), 7.19 (d, J = 8.5Hz, 1H), 7.08 (d, J = 8.8Hz, 2H), 6.82 (s, 1H), 5.65 (s, 1H).

Claims

1. A method for preparing 3,4'-dichlorodiphenyl ether from difenoconazole waste, the method comprising the following steps: (1) Add 10-32% hydrochloric acid and difenoconazole waste to the reaction flask and react at 84-108℃ to generate a mixture of ring-opening intermediates. Cool the mixture and filter to obtain an aqueous intermediate product A. (2) Add solvent A and aqueous intermediate product A to the reaction flask, dehydrate by heating and reflux until the water content is qualified, and cool down to obtain anhydrous intermediate product A and solvent A mixture. (3) Add solvent B and alkali to the reaction flask, raise the temperature and maintain it at 100-140℃, add anhydrous intermediate product A and solvent A mixture dropwise, after the reaction is completed, the reaction system is washed with water and desolventized to obtain crude 3,4'-dichlorodiphenyl ether; the weight ratio of solvent B to difenoconazole waste is 2-5:

1.

2. The method according to claim 1, characterized in that... The difenoconazole waste from step (1) contains 1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole (compound I), 4-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-4H-[1,2,4]triazole (compound II), and 1-{2-[4-chloro-2-(4-chlorophenoxy)-phenyl]-4-methyl-[1,3]dioxolane-2-ylmethyl}-1H-[1,2,4]triazole (compound III), whose chemical structures are as follows: The reaction equation for step (1) is as follows:

3. The method according to claim 1 or 2, characterized in that, The reaction equation for step (3) is as follows:

4. The method according to claim 1, characterized in that... In step (2), solvent A is toluene and / or xylene, and the weight ratio of intermediate product A to solvent is 1:1-5.

5. The method according to claim 1, characterized in that... The alkali mentioned in step (3) is sodium hydroxide and / or potassium hydroxide.

6. The method according to claim 1, characterized in that... The solvent B mentioned in step (3) is one or a mixture of several solvents, including toluene, xylene, methanol, and ethanol.

7. The method according to claim 1, characterized in that... In step (3), the weight ratio of the alkali to the difenoconazole waste is 0.5-1:

1.

8. The method according to claim 1, characterized in that... The crude 3,4'-dichlorodiphenyl ether obtained in step (3) was further distilled to obtain the finished 3,4'-dichlorodiphenyl ether product.

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