Resourceful treatment method for 2-chloro-4-(4-chlorophenoxy) acetophenone raffinate

Abstract

The invention relates to a resourceful treatment method for 2-chloro-4-(4-chlorophenoxy) acetophenone raffinate, which comprises the following steps of: separating high-value 2-chloro-4-(4-chlorophenoxy) acetophenone from the 2-chloro-4-(4-chlorophenoxy) acetophenone raffinate, and simultaneously converting the separated isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone into 3, 4-dichloro-2-(4-chlorophenoxy)-phenyl]-ethanone, according to the present invention, the 2, 4 '-dichlorodiphenyl ether is added, such that the efficient cyclic utilization is achieved, and the production cost of the difenoconazole is substantially reduced. Compared with other existing recovery processes, equipment needed by the process is conventional equipment, reaction is normal pressure reaction, the process route is simple, reaction steps are few, operation is easy, production cost is low, safety is higher, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical synthesis. More specifically, the present invention relates to a method for resource recovery treatment of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid. Background Art

[0002] Difenoconazole, also known as oxaclostrobin, with the trade name "Shigao", is a sterol demethylation inhibitor with the characteristics of high efficiency, broad spectrum, low toxicity and long lasting effect. It is a high-quality variety with relatively high safety among triazole fungicides. Due to its excellent properties such as good systemic absorption and fumigation, it has broad market prospects.

[0003] 2-Chloro-4-(4-chlorophenoxy)acetophenone is a key intermediate in the synthesis of difenoconazole. The synthesis method mainly uses 3,4'-dichlorodiphenyl ether and acetyl chloride as raw materials and aluminum trichloride as catalyst to carry out Friedel-Crafts acylation reaction to prepare the crude product, which is then purified by solvent crystallization to obtain the fine product.

[0004] The main reaction equation of 2-chloro-4-(4-chlorophenoxy)acetophenone is:

[0005]

[0006] The side reaction equation of 2-chloro-4-(4-chlorophenoxy)acetophenone is:

[0007]

[0008] In the process of producing 2-chloro-4-(4-chlorophenoxy)acetophenone using the above method, side reactions are inevitable. Usually, the main product 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) accounts for about 95% (by mass ratio), and the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II) accounts for about 5%.

[0009] Domestic companies have separated these two substances through crystallization, achieving a 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) content exceeding 99% and a yield of approximately 88%. The residue after removing the solvent from the crystallization mother liquor is called 2-chloro-4-(4-chlorophenoxy)acetophenone residue, which contains 70%-80% 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) and 20-30% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II), with the remainder being impurities.

[0010] For the above-mentioned 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, Chinese invention patent CN 113717035A reports a treatment method. In this method, the raw material 3,4'-dichlorodiphenyl ether is acylated and purified to prepare the difenoconazole intermediate 1-(2-chloro-4-(4-chlorophenoxy)phenyl)ethanone. The refined mother liquor is recovered and reacted with hydrazine hydrate under alkaline conditions to form a hydrazone derivative. While the excess hydrazine hydrate is distilled off at high temperature, the hydrazone derivative decomposes into a mixture of 1-(2-chloro-4-(4-chlorophenoxy)phenyl)ethane and 1-(4-chloro-2-(4-chlorophenoxy)phenyl)ethane. The mixture undergoes a Friedel-Crafts dealkylation reaction in the presence of a Lewis acid to release ethane and obtain crude 3,4'-dichlorodiphenyl ether. The crude 3,4'-dichlorodiphenyl ether is then distilled to obtain refined 3,4'-dichlorodiphenyl ether. This method involves three steps of reaction, which is a long route. In addition, the high-value 2-chloro-4-(4-chlorophenoxy)acetophenone is converted into low-value 3,4'-dichlorodiphenyl ether, resulting in a high overall cost.

[0011] Chinese invention patent application CN 113956136A reports another treatment method, which involves mixing a certain amount of residue, water, and liquid caustic soda and maintaining the mixture under a certain pressure. Separation is then performed, the aqueous phase is extracted, and the organic phases are combined. The mixture is then washed, separated, recovered under reduced pressure, and evaporated under high vacuum to yield 3,4'-dichlorodiphenyl ether. However, this method involves a pressurized reaction at a pressure of 0.4-0.8 MPa, posing a high safety risk during production. Furthermore, the high-value 2-chloro-4-(4-chlorophenoxy)acetophenone is converted into the low-value 3,4'-dichlorodiphenyl ether, making it economically unsuitable.

[0012] Both of the above methods use 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid as a raw material to convert the corresponding intermediates, resulting in low economic benefits and high safety risks. Currently, there is no technology in the industry that can completely separate 2-chloro-4-(4-chlorophenoxy)acetophenone and the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone from the 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, and there is no resource recovery method for the separated isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone. Therefore, a new method for recycling and utilizing 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid is needed. Summary of the Invention

[0013] The present invention aims to provide a method for resource-based treatment of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid. The method is intended to completely separate 2-chloro-4-(4-chlorophenoxy)acetophenone and its isomer, 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, through a novel technology. Simultaneously, the separated isomer, 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, is converted into 3,4'-dichlorodiphenyl ether, thereby achieving resource utilization of the 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid and reducing the production cost of difenoconazole. Furthermore, the recovery method is intended to be simple and easy to operate, with mild reaction conditions, thereby improving the safety and cost-effectiveness of the recovery technology.

[0014] To achieve the above-mentioned object, the present invention provides a method for resource recovery of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, which comprises separating 2-chloro-4-(4-chlorophenoxy)acetophenone and the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone from the 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, and the steps are as follows:

[0015] (1) Add 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, solvent S1 and activated carbon to the reactor, heat and decolorize, filter, cool and crystallize the filtered mother liquor, continue to keep warm until no new solid precipitates after solid precipitation, and obtain solid material A and filtered mother liquor B after filtration;

[0016] (2) Add the solid material A and solvent S1 in step (1) to the reactor, increase the temperature until the solid material is completely dissolved, cool and crystallize, and continue to keep the temperature until no new solid precipitates after the solid precipitates, and filter to obtain the finished product of 2-chloro-4-(4-chlorophenoxy)acetophenone and the filtered mother liquor C;

[0017] (3) Add the filtered mother liquor B in step (1) to the reactor, remove part of the solvent, cool and crystallize, and continue to keep warm until no new solid precipitates after solid precipitation. After filtering, obtain the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone and the filtered mother liquor D;

[0018] (4) Add the filtered mother liquor C in step (2) and the filtered mother liquor D in step (3) to the reactor, heat the mixture to remove the solvent S1, and obtain a concentrated material E. The obtained concentrated material is returned to step (1), and steps (1) to (3) are repeated until the isomers 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone and 2-chloro-4-(4-chlorophenoxy)acetophenone in the residual liquid are completely separated.

[0019] As a preferred embodiment, the above treatment method further comprises the step of preparing 3,4'-dichlorodiphenyl ether from the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, specifically:

[0020] (5) Add the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), a base and a solvent S2 into a reaction vessel, raise the temperature to react, and convert 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone into 3,4'-dichlorodiphenyl ether. After the reaction is completed, the reaction system is washed with water, desolventized and distilled to obtain 3,4'-dichlorodiphenyl ether.

[0021] In the present invention, the raw material 2-chloro-4-(4-chlorophenoxy)acetophenone residue used in step (1) is the residue obtained by removing the crystallization solvent from the crystallization mother liquor after preparing 2-chloro-4-(4-chlorophenoxy)acetophenone by the existing technology. According to the HPLC area normalization method, the residue contains 70% to 80% of 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I), 20% to 30% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II), and the rest are impurities.

[0022] In the present invention, the solvent S1 in step (1) is a mixture of one or more solvents selected from the group consisting of heptane, petroleum ether, n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane. When a mixed solvent is used, there is usually no need to limit the ratio of the mixed solvents.

[0023] The solvent, activated carbon and other raw materials of the present invention are all products commonly sold on the market.

[0024] According to a preferred embodiment of the present invention, the amount of solvent S1 in step (1) is 1-6 times the mass of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone, preferably 2-5 times; the amount of activated carbon is 0.5-2% of the mass of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone, preferably 0.8-1.5%.

[0025] In the present invention, the temperature for the decolorization by heating in step (1) is 40 to 60° C., preferably 45 to 55° C.; the temperature for the crystallization by cooling is 0 to 25° C., preferably 5 to 20° C. Both decolorization by heating and crystallization by cooling are common knowledge in the art, and those skilled in the art can also adjust the decolorization and / or crystallization conditions according to actual working conditions.

[0026] The solid material A obtained in this step contains 92%-98% of 2-chloro-4-(4-chlorophenoxy)acetophenone and 2%-8% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (calculated by HPLC area normalization method, the same below).

[0027] In the present invention, the weight of the solvent S1 in step (2) is 0.8-3 times the mass of the solid material, preferably 1-2 times; the heating temperature is 55-75°C, preferably 60-70°C; the cooling crystallization temperature is 5-30°C, preferably 10-25°C.

[0028] Typically, the content of 2-chloro-4-(4-chlorophenoxy)acetophenone obtained in this step is above 99%.

[0029] In the present invention, after removing part of the solvent from the filtered mother liquor B in step (3), the weight of the remaining solvent is 1-3 times, preferably 1.5-2.5 times, the weight of the remaining material, which is the weight difference between the residual liquid of 2-chloro-4-(4-chlorophenoxy)acetophenone and the solid material A added to the reactor in step (1).

[0030] The purpose of removing part of the solvent from the filtered mother liquor B is to adjust the mass ratio of the remaining material to the solvent in the reaction system. Generally, when the mass ratio is 1:1 to 3, preferably 1:1.5 to 2.5, it is beneficial to the subsequent steps. If too little solvent is removed, that is, too much solvent remains in the reaction system, the crystallization yield of the subsequent process will be too low. If the amount of solvent removed is too much, that is, there is less residual solvent, although crystallization can be performed in the subsequent process, the reaction system is relatively viscous, and the quality of the obtained material will decrease. If there is too little residual solvent, it may be difficult to stir, affecting the normal progress of the reaction.

[0031] In order to ensure that the treatment method of the present invention can be carried out normally, those skilled in the art may also appropriately adjust the amount of solvent removed in step (3). In this step, the removal of part of the solvent can be carried out by desolvation under normal pressure or reduced pressure, which are common knowledge known to those skilled in the art and will not be elaborated here.

[0032] According to a preferred embodiment of the present invention, the temperature of the cooling crystallization in step (3) is 10-35°C, preferably 15-30°C.

[0033] Typically, the content of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone obtained in this step is above 96%.

[0034] In the present invention, in step (4), the filtered mother liquor C in step (2) and the filtered mother liquor D in step (3) are heated to remove the solvent, thereby obtaining a concentrated material E, which contains 70%-80% of 2-chloro-4-(4-chlorophenoxy)acetophenone, 20%-30% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, and the remainder being impurities.

[0035] In the present invention, the alkali in step (5) is potassium hydroxide and / or sodium hydroxide. The solvent S2 is toluene, xylene, trimethylbenzene, m-dichlorobenzene or a mixture thereof. When a mixed solvent is used, there is usually no need to limit their ratio.

[0036] Preferably, in step (5), the molar ratio of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone to the base is 1:2-5, preferably 1:3-4. The weight ratio of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone to the solvent S2 is 1:3-6, preferably 1:4-5.

[0037] The present invention separates high-value 2-chloro-4-(4-chlorophenoxy)acetophenone from 2-chloro-4-(4-chlorophenoxy)acetophenone residue by adopting the resource recovery treatment method, and simultaneously converts the separated isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone into 3,4'-dichlorodiphenyl ether, thereby achieving efficient recycling and greatly reducing the production cost of difenoconazole.

[0038] Compared with the existing recovery process, the treatment method of the present invention requires conventional equipment, the reactions are all normal pressure reactions, the process route is simple, the reaction steps are few, the operation is simple, the production cost is low, the safety is higher, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a HPLC liquid chromatogram of the residual liquid of 2-chloro-4-(4-chlorophenoxy)acetophenone, a raw material used in the present invention;

[0040] Figure 2 This is an HPLC liquid chromatogram of the product of 2-chloro-4-(4-chlorophenoxy)acetophenone in step (2) of the preparation method of the present invention.

[0041] Figure 3 This is the HPLC liquid chromatogram of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3) of the preparation method of the present invention.

[0042] Figure 4 This is the HPLC liquid chromatogram of 3,4'-dichlorodiphenyl ether in step (5) of the preparation method of the present invention. DETAILED DESCRIPTION

[0043] The following examples are used to illustrate the technical solutions of the present invention in a non-limiting manner.

[0044] In the present invention, the analysis conditions of liquid chromatography are: Tnature C18, 5μm, 4.6×150mm chromatographic column, mobile phase is methanol:acetonitrile:0.5% phosphoric acid aqueous solution = 5:75:20 (mass ratio), flow rate 1ml / min, wavelength 230nm.

[0045] In the present invention, unless otherwise specified, "%" used to explain concentration refers to mass percentage.

[0046] In the present invention, the HPLC content data "%" described in the synthesis examples are all area-normalized contents.

[0047] The present invention will be better understood through the following examples.

[0048] Example 1:

[0049] After preparing 2-chloro-4-(4-chlorophenoxy)acetophenone by existing technology, the residual liquid after removing the crystallization solvent from the crystallization mother liquor was used as the raw material, and the main components in the mother liquor were confirmed by liquid chromatography:

[0050] 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I), the content is 73.2%, the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II), the content is 25.2%, such as Figure 1 shown.

[0051] Step (1): Add 5 kg of cyclohexane to a 10 L reactor, start stirring and heat to 50 ° C, add 1 kg of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid and 10 g of activated carbon, stir for half an hour, filter the resulting filtrate and add it to another 10 L reactor, slowly cool the filtrate to 8 ° C to precipitate solids, keep the temperature at 8 ° C for 2 hours to allow the reaction system to fully precipitate solids, and filter to obtain 371 g of solid material A (analysis showed that it contained 97.8% of compound I and 97.8% of compound II).

[0052] 1.2%), and 5.54 kg of filtered mother liquor B.

[0053] Step (2): Add 371 g of solid material A obtained in step (1) and 620 g of cyclohexane to a 2 L reactor, heat to 60 ° C and stir for half an hour, then slowly cool to 20 ° C. After solid precipitation, maintain 20 ° C for 2 hours to allow the reaction system to fully precipitate solids, and filter to obtain 326 g of 2-chloro-4-(4-chlorophenoxy)acetophenone finished product (analysis showed that it contained compound

[0054] Ⅰ99.5%, compound Ⅱ0.5%, attached Figure 2 ), and 631 g of filtered mother liquor C.

[0055] Step (3): Add 5.54 kg of filtered mother liquor B in step (1) to a 10 L reactor, remove 3.09 kg of cyclohexane, then cool to 20 ° C for crystallization. After the solid precipitates, continue to keep warm for 1 hour, and filter to obtain 122 g of isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (analysis showed that it contained 3.5% of compound I, 96.5% of compound II, and 10.5% of compound II). Figure 3 ), and 2.25 kg of filtered mother liquor D.

[0056] Step (4): 631 g of filtered mother liquor C from step (2) and 2.25 kg of filtered mother liquor D from step (3) were added to a 5 L reactor. After heating to remove cyclohexane, 544 g of concentrated material E (containing 73.2% of compound I and 24.1% of compound II after analysis) was obtained. The concentrated material was applied to step (1) of the next batch of materials.

[0057] Step (5): 122 g of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), 98 g of potassium hydroxide and 600 g of xylene were added to a 2 L reactor, and the temperature was raised to 120° C. for reaction for 2 hours. HPLC analysis confirmed that the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in the system was less than 1%, indicating that the reaction was complete. The temperature was lowered to 60° C., 200 g of water was added, and the mixture was stirred for 15 minutes and allowed to stand for stratification. After the upper organic layer was decompressed to remove the solvent xylene, 88 g of 3,4'-dichlorodiphenyl ether was obtained by further distillation, and the content was 99.1% (attached). Figure 4 ).

[0058] Example 2:

[0059] Another batch of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid was taken and confirmed by the same method as in Example 1 to contain 74.8% of 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) and 24.4% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II).

[0060] Step (1): 3 kg of heptane was added to a 10 L reactor, stirring was started and the temperature was raised to 55 ° C. 456 g of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone, 544 g of the concentrated material E in step (4) of Example 1 and 18 g of activated carbon were added, and the mixture was stirred for half an hour. The filtrate was filtered and added to another 10 L reactor, and the temperature was slowly lowered to 0 ° C. to precipitate solids. The temperature was continued for 2 hours to allow the reaction system to fully precipitate solids. After filtration, 379 g of solid material A (analysis showed that it contained 94.8% of compound I and 3.7% of compound II) and 3.55 kg of filtered mother liquor B were obtained.

[0061] Step (2): 379 g of solid material A obtained in step (1) and 379 g of heptane were added to a 2 L reactor, heated to 65 ° C and stirred for half an hour, then slowly cooled to 15 ° C. After solid precipitation, the temperature was kept at 1 hour to fully precipitate the solid, and 334 g of 2-chloro-4-(4-chlorophenoxy)acetophenone was obtained by filtration (the analysis showed that the content of compound I was 99.1%, compound II

[0062] 0.9%), and 396 g of filtered mother liquor C.

[0063] Step (3): 3.55 kg of filtered mother liquor B in step (1) was added to a 10 L reactor, and the temperature was raised at normal pressure to remove 1.56 kg of heptane. The temperature was lowered to 30 ° C for crystallization. After the solid precipitated, the temperature was kept for 1 hour, and 119 g of isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (analysis showed that it contained 3.1% of compound I and 96.9% of compound II) was obtained by filtration, and 1.86 kg of filtered mother liquor D was obtained.

[0064] Step (4): 396 g of filtered mother liquor C from step (2) and 1.86 kg of filtered mother liquor D from step (3) were added to a 5 L reactor. After heating to remove the heptane, 539 g of concentrated material E (containing 74.5% of compound I and 22.8% of compound II after analysis) was obtained, which was applied to step (1) of the next batch of materials.

[0065] Step (5): 119 g of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), 71 g of potassium hydroxide and 480 g of toluene were added to a 2 L reactor, and the temperature was raised to 108 ° C. for reaction for 3 hours. HPLC analysis confirmed that the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone was less than 1%, indicating that the reaction was complete. The temperature was lowered to 60 ° C., 150 g of water was added, and the mixture was stirred for 15 minutes and then allowed to stand for stratification. After the upper organic layer was decompressed to remove the solvent toluene, it was continued to distill to obtain 62 g of 3,4'-dichlorodiphenyl ether with a content of 99.3%.

[0066] Example 3:

[0067] Another batch of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid was taken and confirmed to contain 70.1% of 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) and 28.3% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II) by the same method as in Example 1.

[0068] Step (1): 1.5 kg of petroleum ether was added to a 10 L reactor, stirring was started, the temperature was raised to 45 ° C, 461 g of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone, 539 g of the concentrated material E in step (4) of Example 2 and 6 g of activated carbon were added, and the mixture was stirred for half an hour. The filtrate was filtered and added to another 10 L reactor, and the temperature was slowly lowered to 22 ° C to precipitate solids. The mixture was kept warm for 2 hours to fully precipitate the solids. After filtration, 364 g of solid material A (containing 93.4% of compound I and 4.9% of compound II) and 2.08 kg of filtered mother liquor B were obtained.

[0069] Step (2): 364 g of solid material A obtained in step (1) and 910 g of petroleum ether were added to a 2 L reactor, heated to 60° C., stirred for half an hour, and slowly cooled to 5° C. After solid precipitation, the mixture was kept warm for 1.5 hours and filtered to obtain 300 g of 2-chloro-4-(4-chlorophenoxy)acetophenone product (analysis showed that it contained 99.3% of compound I and 0.7% of compound II) and 939 g of filtered mother liquor C.

[0070] Step (3): 2.08 kg of filtered mother liquor B in step (1) was added to a 10 L reactor, and the temperature was raised at normal pressure to remove 681 g of petroleum ether. The temperature was lowered to 21 ° C for crystallization. After solid precipitation, the temperature was kept warm for 1 hour until the solid was fully precipitated. After filtration, 121 g of isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (analysis showed that it contained 2.8% of compound I and 97.2% of compound II) and 1.23 kg of filtered mother liquor D were obtained.

[0071] Step (4): 939 g of filtered mother liquor C from step (2) and 1.23 kg of filtered mother liquor D from step (3) were added to a 5 L reactor. After heating to remove the petroleum ether, 569 g of concentrated material E (containing 74.3% of compound I and 23.6% of compound II after analysis) was obtained, which was applied to the next batch of materials.

[0072] Step (5): 121 g of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), 60 g of potassium hydroxide and 370 g of trimethylbenzene were added to a 2 L reactor, and the temperature was raised to 118 ° C. to react for 2 hours. HPLC analysis confirmed that the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone was less than 1%, indicating that the reaction was completed. The temperature was lowered to 60 ° C., 120 g of water was added, and the mixture was stirred for 15 minutes and then allowed to stand for stratification. After the upper organic layer was decompressed to remove the solvent trimethylbenzene, it was continued to distill to obtain 51 g of 3,4'-dichlorodiphenyl ether with a content of 99.0%.

[0073] Example 4:

[0074] Another batch of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid was taken and confirmed to contain 76.1% of 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) and 22.6% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II) by the same method as in Example 1.

[0075] Step (1): 4 kg of n-hexane was added to a 10 L reactor, stirring was started, the temperature was raised to 50 ° C, 431 g of 2-chloro-4-(4-chlorophenoxy)acetophenone residue, 569 g of concentrated material E in step (4) of Example 3 and 11 g of activated carbon were added, and the mixture was stirred for half an hour. The filtrate was filtered and added to another 10 L reactor, and the temperature was slowly lowered to 15 ° C to precipitate solids. The mixture was kept warm for 2 hours and filtered to obtain 368 g of solid material A (analysis showed that it contained 95.7% of compound I and 3.1% of compound II) and 4.52 kg of filtered mother liquor B.

[0076] Step (2): 368 g of solid material A obtained in step (1) and 450 g of n-hexane were added to a 2 L reactor, heated to 62 ° C and stirred for half an hour, then slowly cooled to 25 ° C. After solid precipitation, the temperature was kept at this temperature for 2 hours. After the solid was fully precipitated, it was filtered to obtain 323 g of 2-chloro-4-(4-chlorophenoxy)acetophenone finished product (analysis showed that it contained 99.2% of compound I and 99.2% of compound II).

[0077] 0.8%), and 463 g of filtered mother liquor C.

[0078] Step (3): 4.52 kg of filtered mother liquor B in step (1) was added to a 10 L reactor, and the temperature was raised at normal pressure to remove 2.90 kg of n-hexane. The temperature was lowered to 12 ° C for crystallization. After the solid precipitated, the temperature was kept for 1 hour and filtered to obtain 118 g of isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (analysis showed that it contained 2.6% of compound I and 97.4% of compound II) and 1.43 kg of filtered mother liquor D.

[0079] Step (4): 463 g of filtered mother liquor C from step (2) and 1.43 kg of filtered mother liquor D from step (3) were added to a 5 L reactor. After heating to remove the n-hexane, 552 g of concentrated material E (containing 76.5% of compound I and 20.5% of compound II after analysis) was obtained, which was applied to the next batch of materials.

[0080] Step (5): 118 g of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), 110 g of potassium hydroxide and 650 g of m-dichlorobenzene were added to a 2 L reactor, and the temperature was raised to 110 ° C. to react for 3 hours. HPLC analysis confirmed that the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone was less than 1%, indicating that the reaction was completed. The temperature was lowered to 60 ° C., 250 g of water was added, and the mixture was stirred for 15 minutes and then allowed to stand for stratification. After the upper organic layer was decompressed to remove the solvent m-dichlorobenzene, it was continued to distill to obtain 92 g of 3,4'-dichlorodiphenyl ether with a content of 99.5%.

[0081] Example 5:

[0082] Another batch of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid was taken and confirmed to contain 71.2% of 2-chloro-4-(4-chlorophenoxy)acetophenone (Compound I) and 27.8% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (Compound II) by the same method as in Example 1.

[0083] Step (1): Add 2 kg of methylcyclohexane to a 10 L reactor, start stirring, heat to 55 ° C, add 448 g of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, 552 g of concentrated material E in step (4) of Example 4 and 13 g of activated carbon, stir for half an hour, filter, add the filtrate to another 10 L reactor, slowly cool to 10 ° C, precipitate solid, continue to keep warm for 2 hours, filter, and obtain 372 g of solid material A (analysis contains compound I

[0084] 92.4%, compound II 6.1%), and 2.57 kg of filtered mother liquor B.

[0085] Step (2): 372 g of solid material A obtained in step (1) and 550 g of methylcyclohexane were added to a 2 L reactor, and the temperature was raised to 70° C., stirred for half an hour, and slowly cooled to 16° C. After solid precipitation, the mixture was kept warm for 2 hours and filtered to obtain 309 g of 2-chloro-4-(4-chlorophenoxy)acetophenone product (analysis showed that it contained 99.3% of compound I and 0.7% of compound II) and 586 g of filtered mother liquor C.

[0086] Step (3): 2.57 kg of filtered mother liquor B in step (1) was added to a 10 L reactor, and the temperature was raised at normal pressure to remove 686 g of methylcyclohexane. The temperature was lowered to 15 ° C for crystallization. After the solid precipitated, the temperature was continued to be kept for 1 hour, and filtered to obtain 120 g of isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone (analysis showed that it contained 1.7% of compound I and 98.3% of compound II) and 1.71 kg of filtered mother liquor D.

[0087] Step (4): 586 g of filtered mother liquor C from step (2) and 1.71 kg of filtered mother liquor D from step (3) were added to a 5 L reactor. After heating to remove the methylcyclohexane, 561 g of concentrated material E (containing 76.7% of compound I and 20.8% of compound II after analysis) was obtained, which was applied to the next batch of materials.

[0088] Step (5): 120 g of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), 60 g of sodium hydroxide and 500 g of xylene were added to a 2 L reactor, and the temperature was raised to 115 ° C. to react for 2 hours. HPLC analysis confirmed that the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone was less than 1%, indicating that the reaction was completed. The temperature was lowered to 60 ° C., 120 g of water was added, and the mixture was stirred for 15 minutes and then allowed to stand for stratification. After the upper organic layer was decompressed to remove the solvent xylene, it was continued to distill to obtain 47 g of 3,4'-dichlorodiphenyl ether with a content of 99.4%.

[0089] The treatment method of the present invention uses the residual liquid after removing the crystallization solvent from the crystallization mother liquor after preparing 2-chloro-4-(4-chlorophenoxy)acetophenone as a raw material, separates the high-value 2-chloro-4-(4-chlorophenoxy)acetophenone product in the residual liquid, and the content of 2-chloro-4-(4-chlorophenoxy)acetophenone is higher than 99.1%. At the same time, the separated isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone is further converted into a high-value 3,4'-dichlorodiphenyl ether product, and the content of the obtained 3,4'-dichlorodiphenyl ether is higher than 99.0%. The efficient recycling of the chemical residual liquid is achieved, and the production cost of difenoconazole is greatly reduced.

[0090] The method of the present invention has a simple process route, few reaction steps, low production cost, high safety, and is suitable for promotion.

Claims

1. A method for resource recovery of 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, characterized in that The method comprises separating 2-chloro-4-(4-chlorophenoxy)acetophenone and the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone from a 2-chloro-4-(4-chlorophenoxy)acetophenone residue, comprising the following steps: (1) Add 2-chloro-4-(4-chlorophenoxy)acetophenone residual liquid, solvent S1 and activated carbon to the reactor, heat and decolorize, filter, cool and crystallize the filtered mother liquor, continue to keep warm until no new solid precipitates after solid precipitation, and obtain solid material A and filtered mother liquor B after filtration; (2) Add the solid material A and solvent S1 in step (1) to the reactor, increase the temperature until the solid material is completely dissolved, cool and crystallize, and continue to keep the temperature until no new solid precipitates after the solid precipitates, and filter to obtain the finished product of 2-chloro-4-(4-chlorophenoxy)acetophenone and the filtered mother liquor C; (3) Add the filtered mother liquor B in step (1) to the reactor, remove part of the solvent, cool and crystallize, and continue to keep warm until no new solid precipitates after solid precipitation. After filtering, obtain the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone and the filtered mother liquor D; (4) Add the filtered mother liquor C in step (2) and the filtered mother liquor D in step (3) to the reactor, heat the mixture to remove the solvent S1, and obtain a concentrated material E. The obtained concentrated material is returned to step (1), and steps (1) to (3) are repeated until the isomers 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone and 2-chloro-4-(4-chlorophenoxy)acetophenone in the residual liquid are completely separated.

2. The method according to claim 1, characterized in that The method further comprises the step of preparing 3,4'-dichlorodiphenyl ether from the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, the steps being as follows: (5) Add the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone in step (3), a base and a solvent S2 into a reaction vessel, raise the temperature to react, and convert 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone into 3,4'-dichlorodiphenyl ether. After the reaction is completed, the reaction system is washed with water, desolventized and distilled to obtain 3,4'-dichlorodiphenyl ether.

3. The method according to claim 1, characterized in that According to the HPLC area normalization method, the 2-chloro-4-(4-chlorophenoxy)acetophenone residue in step (1) contains 70% to 80% of 2-chloro-4-(4-chlorophenoxy)acetophenone, 20% to 30% of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone, and the rest are impurities.

4. The method according to claim 1, characterized in that In step (1), the solvent S1 is selected from one or more solvents selected from heptane, petroleum ether, n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane; the amount of solvent S1 in step (1) is 1-6 times the amount of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone by mass ratio; the amount of activated carbon is 0.5-2% of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone; the heating decolorization is achieved by heating the reaction system to 40-60°C and keeping it warm for half an hour, and the cooling crystallization temperature is 0-25°C.

5. The method according to claim 1, characterized in that In terms of mass ratio, the solvent S1 in step (2) is 0.8-3 times the weight of the solid material A; the heating temperature is 55-75°C, and the cooling crystallization temperature is 5-30°C.

6. The method according to claim 1, characterized in that The crystallization temperature during the cooling step (3) is 10-35°C.

7. The method according to claim 1, characterized in that In step (3), part of the solvent is removed until the weight of the remaining solvent is 1-3 times the weight of the remaining material, where the weight of the remaining material is the difference between the weight of the residual 2-chloro-4-(4-chlorophenoxy)acetophenone and the solid material A added to the reactor in step (1).

8. The method according to claim 1, characterized in that The reaction equation of step (5) is as follows:

9. The method according to claim 1, characterized in that The base described in step (5) is potassium hydroxide and / or sodium hydroxide, and the solvent S2 is selected from one or more of toluene, xylene, trimethylbenzene, and m-dichlorobenzene.

10. The method according to claim 1, characterized in that In step (5), the molar ratio of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone to the base is 1:2-5; the weight ratio of the isomer 1-[4-chloro-2-(4-chlorophenoxy)-phenyl]-ethanone to the solvent S2 is 1:3-6.

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