A post-treatment process for m-trifluoromethylacetophenone oxime

Abstract

The present invention relates to the technical field of chemical production, and specifically discloses a post-treatment process of m-trifluoromethylacetophenone oxime. Specifically comprising the following steps: adding a copper complexing agent to a coupling reaction liquid, stirring the reaction, standing, separating the liquids, alkali washing the obtained oil phase to neutrality, and obtaining a m-trifluoromethylacetophenone oxime reaction liquid; concentrating the m-trifluoromethylacetophenone oxime reaction liquid, cooling and crystallizing, solid-liquid separation, washing, and drying to obtain a m-trifluoromethylacetophenone oxime product. The post-treatment process of m-trifluoromethylacetophenone oxime provided by the present invention eliminates the need to first hydrolyze after the coupling reaction in the traditional process, and then react with hydroxylamine to produce m-trifluoromethylacetophenone oxime, which not only significantly improves the production efficiency of m-trifluoromethylacetophenone oxime, but also avoids the generation of a large amount of waste salt in the hydrolysis and oximation steps, saves the solvent recovery step, reduces the hazardous waste treatment cost of the enterprise, is suitable for industrial production, and has a high value for promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, and in particular to a post-treatment process of m-trifluoromethylacetophenone oxime. Background Art

[0002] 3-Trifluoromethylacetophenone oxime is a key intermediate of the methoxyacrylate fungicide trifloxystrobin and is also a promising candidate for the synthesis of isoflurane. The key intermediate of azole and oxime ether insecticides. At present, the process of synthesizing m-trifluoromethylacetophenone oxime mainly includes: the first, m-trifluoromethylacetophenone and hydroxylamine undergo oximation reaction to obtain m-trifluoromethylacetophenone oxime, the reaction yield is generally above 95%, which is the most widely used process route in industrial production. The second, using 1-(3-trifluoromethylphenyl)-ethylamine as raw material and peracetic acid as oxidant, through oxidation reaction, m-trifluoromethylacetophenone oxime is obtained, and the reaction yield is about 91%. The conversion rate of the above two synthesis processes is relatively high, but the common problem is that the raw materials m-trifluoromethylacetophenone and 1-(3-trifluoromethylphenyl)-ethylamine are relatively high in price, and the production cost is high.

[0003] According to literature reports, 1-(3-trifluoromethylphenyl)-ethylamine is prepared from m-trifluoromethylacetophenone by amination and high-pressure hydrogenation. It can be seen that the key to the above two processes is the synthesis of m-trifluoromethylacetophenone. At present, the main synthesis process of m-trifluoromethylacetophenone is: m-trifluoromethylaniline is used as a raw material, firstly undergoes a diazotization reaction with hydrochloric acid (or sulfuric acid) and sodium nitrite, and the resulting diazonium salt is coupled with acetaldehyde oxime under a certain pH condition under the catalysis of copper ions, and then hydrolyzed with concentrated hydrochloric acid (or sulfuric acid) to obtain m-trifluoromethylacetophenone. The reported conversion rate can reach 75-80%. The raw materials used in this process are all bulk commodities, the price is relatively low, the reaction conditions are relatively mild, and the process is safe. It is currently the most commonly used process route for producing m-trifluoromethylacetophenone.

[0004] However, the above-mentioned process route is complicated, and the hydrolysis process also produces a mixture of copper chloride (or copper sulfate) and hydroxylamine hydrochloride (or hydroxylamine sulfate), increasing the amount of wastewater and the difficulty of wastewater treatment. At the same time, the presence of copper ions can significantly aggravate the decomposition of hydroxylamine into nitrogen oxides, polluting the environment. In addition, there are more impurities in the m-trifluoromethylacetophenone solution after hydrolysis, and distillation purification is required to be used as the raw material for synthesizing m-trifluoromethylacetophenone oxime, which not only increases energy consumption, but also consumes hydroxylamine hydrochloride and alkali in the oximation stage of synthesizing m-trifluoromethylacetophenone oxime, increasing the cost of raw materials, and also produces sodium chloride wastewater. Therefore, it is of great significance to provide a method for synthesizing m-trifluoromethylacetophenone oxime with low raw material consumption, less three wastes generation, and simple process route. Summary of the invention

[0005] Aiming at the problems that the existing method for synthesizing m-trifluoromethylacetophenone oxime has a complex process route, a large amount of raw material consumption, and a large amount of waste salt generated during the reaction process, the present invention provides a post-treatment process for m-trifluoromethylacetophenone oxime.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A post-treatment process for m-trifluoromethylacetophenone oxime, the post-treatment process comprising the following steps:

[0008] Step a, adding a copper complexing agent to the coupling reaction solution, stirring the reaction, standing, separating the liquids, and washing the obtained oil phase with alkali until it is neutral to obtain a m-trifluoromethylacetophenone oxime reaction solution;

[0009] Wherein, the copper complexing agent is an alkali metal salt solution of at least one organic acid among divalent or polyvalent carboxylic acids having a carbon number of 5 or more;

[0010] Step b, concentrating the m-trifluoromethylacetophenone oxime reaction solution, cooling and crystallizing, solid-liquid separation, washing, and drying to obtain the m-trifluoromethylacetophenone oxime product.

[0011] It should be noted that the coupling reaction liquid is obtained by diazotization reaction and coupling reaction of m-trifluoromethylaniline, and the oil phase obtained by separation is the coupling reaction liquid in the present invention.

[0012] In order to improve the yield of m-trifluoromethylacetophenone oxime in the prior art, a hydrolysis step is generally required, but the hydrolysis will produce more saline wastewater and cause additional raw material consumption. The inventor studied the reaction process for the purpose of omitting the hydrolysis step during the research and development process, and found that the yield of m-trifluoromethylacetophenone oxime prepared by the coupling reaction step is low, mainly because m-trifluoromethylacetophenone oxime forms a complex intermediate with copper ions, and the complex is an oil-soluble substance, which can increase the solubility of m-trifluoromethylacetophenone oxime, resulting in m-trifluoromethylacetophenone oxime cannot be crystallized and precipitated, therefore, a hydrolysis process of m-trifluoromethylacetophenone oxime is generally required, and m-trifluoromethylacetophenone oxime is continuously converted into m-trifluoromethylacetophenone during the hydrolysis process, and according to the complex dissociation equilibrium, m-trifluoromethylacetophenone oxime and copper ions are gradually dissociated, and finally converted into m-trifluoromethylacetophenone and copper ions, and then distilled to obtain the m-trifluoromethylacetophenone product. Moreover, the formed complex intermediate not only makes a part of the m-trifluoromethylacetophenone oxime unable to be dissociated and separated, but also is mixed in the m-trifluoromethylacetophenone oxime product, resulting in poor product quality.

[0013] In order to skip the hydrolysis step and directly prepare m-trifluoromethylacetophenone oxime, the inventors have tried the following methods:

[0014] The inventor tried to add hydrochloric acid directly to the coupling reaction liquid for washing. The test results showed that washing below 50°C could not increase the yield of m-trifluoromethylacetophenone oxime. Above 50°C, m-trifluoromethylacetophenone oxime began to hydrolyze, and reddish-brown nitrogen oxides were produced, and the process was not feasible. Adding ammonia water to the coupling reaction liquid for washing also failed to increase the yield of m-trifluoromethylacetophenone oxime. Adding 1.3.5-triazine-2.4.6-trithiol trisodium salt (TMT-3Na) or Na2S solution to the coupling reaction liquid, the new copper complex formed has extremely low solubility and small particle size, suspended in the oil phase and the water phase, the oil phase and the water phase cannot be separated, and the m-trifluoromethylacetophenone oxime product cannot be obtained. That is, adding the above-mentioned treating agents to the coupling reaction solution cannot dissociate the complex intermediate formed by m-trifluoromethylacetophenone oxime and copper ions, or the new complex obtained after the dissociation cannot be separated from m-trifluoromethylacetophenone oxime, and the step of replacing the hydrolysis cannot be achieved.

[0015] Compared with the prior art, the post-treatment process of m-trifluoromethylacetophenone oxime provided by the present invention adds a specific copper complexing agent into the coupling reaction liquid, so that the complex intermediate formed by m-trifluoromethylacetophenone oxime and copper ions is fully dissociated, the dissociated m-trifluoromethylacetophenone oxime enters the oil phase, and the formed new copper complex enters the water phase, the oil and water phases are obviously separated, and the m-trifluoromethylacetophenone oxime oil phase can be obtained directly by phase separation, and a high-purity m-trifluoromethylacetophenone oxime product can be directly obtained by simple concentration and cooling crystallization, and the yield of the m-trifluoromethylacetophenone oxime product is effectively improved, and the yield can reach more than 85%.

[0016] The post-treatment process of m-trifluoromethylacetophenone oxime provided by the present invention eliminates the steps of first performing hydrolysis after the coupling reaction and then reacting with hydroxylamine to produce m-trifluoromethylacetophenone oxime in a conventional process, thereby significantly improving the production efficiency of m-trifluoromethylacetophenone oxime and avoiding the generation of a large amount of waste salt in the hydrolysis and oximation steps, reducing the hazardous waste treatment cost of enterprises, being suitable for industrial production, having high economic and environmental benefits, and having extremely high promotion and application value.

[0017] Exemplarily, the steps for preparing the coupling reaction solution are as follows:

[0018] S1, slowly drop m-trifluoromethylaniline into sulfuric acid or hydrochloric acid solution, drop sodium nitrite solution at -5℃~0℃, keep warm for reaction, filter and obtain diazonium salt solution;

[0019] S2, uniformly mix the soluble copper salt, acetic acid, acetaldehyde oxime solution and toluene, dropwise add the diazonium salt solution at 0°C to 5°C, control the system pH to be 4 to 4.5, raise the temperature to 10°C to 20°C after the dropwise addition, keep the temperature for reaction, let stand, separate the liquids, and obtain the coupling reaction liquid.

[0020] The present invention has no special requirements on the preparation process of the coupling reaction liquid. The conventional reaction liquid prepared by using m-trifluoromethylaniline as a raw material through diazotization reaction and coupling reaction in the art can adopt the above-mentioned post-treatment method provided by the present invention to achieve the effect of significantly improving the yield and purity of the m-trifluoromethylacetophenone oxime product.

[0021] Preferably, in step a, the copper complexing agent is sodium or potassium aminotriacetic acid, sodium or potassium diethylenetriaminepentaacetic acid, sodium or potassium methylglycine diacetic acid, sodium or potassium glutamic acid diacetic acid, or sodium or potassium ethylenediaminetetraacetic acid.

[0022] Further preferably, in step a, the alkali metal salt solution is a sodium salt or potassium salt solution of diethylenetriaminepentaacetic acid, or a sodium salt or potassium salt solution of ethylenediaminetetraacetic acid.

[0023] Preferably, in step a, the molar ratio of the alkali metal salt in the copper complexing agent to the copper ions in the coupling reaction solution is 0.4 to 2:1.

[0024] Further preferably, in step a, the molar ratio of the alkali metal salt in the copper complexing agent to the copper ions in the coupling reaction solution is 0.5 to 0.8:1.

[0025] Further preferably, in step a, the mass concentration of the alkali metal salt solution is 10%-30%.

[0026] The preferred copper complexing agent and addition amount can fully dissociate the complex intermediate formed by m-trifluoromethylacetophenone oxime and copper ions, and the formed new copper complex has good stability and water solubility. After directly entering the water phase, the oil-water two-phase stratification is obvious, which effectively improves the yield and purity of m-trifluoromethylacetophenone oxime.

[0027] Preferably, in step a, the stirring reaction temperature is 40° C. to 60° C., and the stirring reaction time is 20 min to 60 min.

[0028] The preferred reaction temperature and time can allow the added copper complexing agent to fully react with the copper complex intermediate of m-trifluoromethylacetophenone oxime to release the chelated m-trifluoromethylacetophenone oxime, thereby increasing the yield of m-trifluoromethylacetophenone oxime.

[0029] Preferably, in step a, the alkali washing adopts sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution or potassium bicarbonate solution with a mass concentration of 10% to 30%.

[0030] It should be noted that the neutrality refers to pH 6-8.

[0031] The preferred alkaline washing can further remove impurities in the meta-trifluoromethylacetophenone oxime oil phase and improve the purity of the meta-trifluoromethylacetophenone oxime product.

[0032] After the copper complexing agent is added and the stirring reaction is completed, the reaction liquid is orange-red. After adding the above-mentioned alkali solution for washing, the color of the reaction liquid is orange or yellow, indicating that the alkali washing removes some impurities in the m-trifluoromethylacetophenone oxime oil phase.

[0033] Preferably, in step b, the concentrated solution is concentrated to a concentration of 30% to 70% of trifluoromethylacetophenone oxime.

[0034] Further preferably, in step b, the concentrated solution is concentrated to a concentration of 45% to 60% of trifluoromethylacetophenone oxime.

[0035] Preferably, in step b, the specific steps of cooling and crystallizing are: cooling to -10°C to 0°C at a rate of 10°C / h to 15°C / h, and keeping the temperature for crystallization for 1.5h to 3h.

[0036] The diazonium salt contained in the coupling reaction solution will also be hydrolyzed in the hydrolysis step to generate trifluoromethylphenol, which has a similar structure to trifluoromethylacetophenone oxime and is difficult to remove by crystallization. In addition, trifluoromethylphenol is easily oxidized to produce colored impurities, which affects the quality of the trifluoromethylacetophenone oxime product.

[0037] The invention adds an alkali washing process after the complexation copper removal, and effectively removes the meta-trifluoromethylphenol. Therefore, a high-purity meta-trifluoromethylacetophenone oxime product can be obtained by simple subsequent cooling and crystallization, and the product is light yellow. The product prepared by the existing traditional process is generally off-white or greenish, and the product quality of the meta-trifluoromethylacetophenone oxime is significantly improved.

[0038] Furthermore, the post-treatment process of the meta-trifluoromethylacetophenone oxime also includes: step c: combining the washing liquid and the crystallization mother liquor obtained in step b, concentrating, cooling and crystallizing, solid-liquid separation, and washing to obtain the meta-trifluoromethylacetophenone oxime product.

[0039] Preferably, in combination with the above, in step c, the concentrated solution is concentrated to a concentration of 40% to 60% of trifluoromethylacetophenone oxime.

[0040] Further in combination with the above, in step c, the concentrated solution is concentrated to a concentration of 50% to 55% of trifluoromethylacetophenone oxime.

[0041] Further in combination with the above, in step c, the specific steps of cooling and crystallizing are: cooling to -5°C to 0°C at a rate of 10°C / h to 15°C / h, and keeping the temperature for crystallization for 1h to 2h.

[0042] The m-trifluoromethylacetophenone oxime in the washing liquid and the crystallization mother liquor is recovered, so that the yield of the m-trifluoromethylacetophenone oxime product can be further improved.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] (1) The present invention directly prepares a high-purity and high-yield m-trifluoromethylacetophenone oxime product by adding a specific copper complexing agent to the coupling reaction solution, wherein the purity of the product can reach more than 99% and the yield can reach more than 85%;

[0045] (2) The coupling reaction liquid does not undergo hydrolysis, distillation, and oximation steps, which greatly simplifies the production process and improves production efficiency;

[0046] (3) It avoids the generation of salt- and acid-containing wastewater during the hydrolysis process and nitrogen oxides produced by the decomposition of hydroxylamine, reduces the company's hazardous waste treatment costs, and reduces raw material consumption, which is in line with the concept of energy conservation and consumption reduction. It is a green production route suitable for industrialization. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] In the following examples and comparative examples, the coupling reaction solution can be prepared according to conventional steps in the art, and the specific steps are as follows:

[0049] Preparation of diazonium salt solution: Slowly add 46g of m-trifluoromethylaniline to a 25% sulfuric acid solution, control the temperature at about 0°C, add 72g of a 30% sodium nitrite solution, keep warm for 1h, filter, and obtain a diazonium salt solution;

[0050] Coupling reaction: pre-cool a mixed solution containing 4.6 g copper sulfate, 8 g acetic acid, 25.1 g acetaldehyde oxime, 30 g water and 100 mL toluene to below 5 ° C, add the above diazonium salt solution dropwise, add 30% mass concentration of liquid alkali to control the pH to 4-4.5 during the addition, heat to 15 ° C after the addition is completed, stir and react for 1 h, let stand and separate, take the oil phase, and obtain 140 g coupling reaction liquid (corresponding to 0.283 mol of m-trifluoromethylaniline).

[0051] The calculation formula for the conversion rate of trifluoromethylacetophenone oxime in the following examples and comparative examples is:

[0052] Conversion rate = external standard content (%) * oil phase mass (g) / theoretical production amount (g) × 100%

[0053] Example 1

[0054] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0055] Step a, add 140g of the above coupling reaction solution to a reactor, add 26.0g of 25% mass concentration tetrasodium glutamate diacetate solution, heat to 40°C, stir and react for 60min, let stand, separate the liquids, wash the oil phase with 15% mass concentration potassium carbonate solution to pH 7-8, separate the liquids to obtain trifluoromethylacetophenone oxime oil phase; the liquid phase external standard trifluoromethylacetophenone content, calculate the oil phase intermediate trifluoromethylacetophenone oxime conversion rate is 88.2%;

[0056] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 59%, cooling to 60°C, cooling to 0°C at a rate of 15°C / h, keeping warm for crystallization for 1.5h, filtering, washing, and drying to obtain 42.3g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.1%;

[0057] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 55% of m-trifluoromethylacetophenone oxime, cooling to 60°C, cooling to 0°C at a rate of 15°C / h, keeping warm for crystallization for 1.5h, filtering with suction, washing, and drying to obtain 8.14g of m-trifluoromethylacetophenone oxime, with an external standard content of 98.5%, and the pure amount of the product obtained by the two crystallizations accounts for 86.9% of the theoretical product mass.

[0058] Example 2

[0059] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0060] Step a, add 140g of the above coupling reaction solution to a reactor, add 40.4g of diethylenetriamine pentaacetic acid pentasodium solution with a mass concentration of 20%, heat to 50°C, stir and react for 20min, let stand, separate the liquids, wash the oil phase with a sodium bicarbonate solution with a mass concentration of 10% to pH 6-7, separate the liquids to obtain the m-trifluoromethylacetophenone oxime oil phase; the liquid phase external standard m-trifluoromethylacetophenone content, calculate the oil phase intermediate trifluoromethylacetophenone oxime conversion rate is 90.3%;

[0061] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 58%, cooling to 60°C, cooling to -5°C at a rate of 10°C / h, keeping warm for crystallization for 2h, filtering, washing, and drying to obtain 42.6g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.7%;

[0062] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 57% of m-trifluoromethylacetophenone oxime, cooling to 55°C, cooling to -5°C at a rate of 10°C / h, keeping warm for crystallization for 2h, filtering with suction, washing, and drying to obtain 8.92g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.0%, and the pure amount of the product obtained by the two crystallizations accounts for 89.3% of the theoretical product mass.

[0063] Example 3

[0064] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0065] Step a, add 140g of the above coupling reaction solution to a reactor, add 25.9g of trisodium aminotriacetate solution with a mass concentration of 20%, heat to 50°C, stir and react for 30min, let stand, separate the liquids, wash the oil phase with a sodium carbonate solution with a mass concentration of 10% to pH 7-8, separate the liquids to obtain the m-trifluoromethylacetophenone oxime oil phase; the liquid phase external standard m-trifluoromethylacetophenone content, calculate the conversion rate of trifluoromethylacetophenone oxime in the oil phase to be 87.4%;

[0066] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 55%, cooling to 55°C, cooling to -5°C at a rate of 15°C / h, keeping warm for crystallization for 3h, filtering, washing, and drying to obtain 40.2g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.5%;

[0067] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 54% of m-trifluoromethylacetophenone oxime, cooling to 55°C, cooling to -5°C at a rate of 15°C / h, keeping warm for crystallization for 1h, filtering with suction, washing, and drying to obtain 9.77g of m-trifluoromethylacetophenone oxime, with an external standard content of 98.7%, and the pure amount of the product obtained by the two crystallizations accounts for 86.4% of the theoretical product mass.

[0068] Example 4

[0069] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0070] Step a, add 140g of the above coupling reaction solution to a reactor, add 51.5g of 15% mass concentration of disodium ethylenediaminetetraacetate solution, heat to 60°C, stir and react for 30min, let stand, separate the liquids, wash the oil phase with 10% mass concentration of sodium hydroxide solution to pH 7-8, separate the liquids to obtain trifluoromethylacetophenone oxime oil phase; the liquid phase external standard trifluoromethylacetophenone content, calculate the oil phase intermediate trifluoromethylacetophenone oxime conversion rate is 90.5%;

[0071] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 60%, cooling to 50°C, cooling to -10°C at a rate of 10°C / h, keeping warm for crystallization for 3h, filtering, washing, and drying to obtain 43.1g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.5%;

[0072] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 55% of m-trifluoromethylacetophenone oxime, cooling to 50°C, cooling to -5°C at a rate of 10°C / h, keeping warm for crystallization for 1h, filtering with suction, washing, and drying to obtain 8.79g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.2%, and the pure amount of the product obtained by the two crystallizations accounts for 89.7% of the theoretical product mass.

[0073] Example 5

[0074] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0075] Step a, add 700g of the above coupling reaction solution to a reactor, add 339g of 10% mass concentration of methylglycine diacetate trisodium solution, heat to 50°C and stir to react for 20min, let stand, separate the liquids, wash the oil phase with 10% mass concentration of potassium bicarbonate solution to pH 7-8, separate the liquids to obtain trifluoromethylacetophenone oxime oil phase; the liquid phase external standard trifluoromethylacetophenone content, calculate the oil phase intermediate trifluoromethylacetophenone oxime conversion rate is 90.8%;

[0076] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 60%, cooling to 50°C, cooling to -5°C at a rate of 10°C / h, keeping warm for crystallization for 2h, filtering, washing, and drying to obtain 220.8g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.0%;

[0077] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 50% of m-trifluoromethylacetophenone oxime, cooling to 50°C, cooling to -5°C at a rate of 10°C / h, keeping warm for crystallization for 2h, filtering, washing, and drying to obtain 39.11g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.2%, and the pure amount of the product obtained by the two crystallizations accounts for 89.6% of the theoretical product mass.

[0078] Example 6

[0079] This embodiment provides a post-treatment process for m-trifluoromethylacetophenone oxime, comprising the following steps:

[0080] Step a, add 140g of the above coupling reaction solution to a reactor, add 39.6g of 15% mass concentration trisodium hydroxyethylethylenediaminetriacetate solution, heat to 40°C, stir and react for 60min, let stand, separate the liquids, wash the oil phase with 15% mass concentration potassium carbonate solution to pH 7-8, separate the liquids to obtain trifluoromethylacetophenone oxime oil phase; the liquid phase external standard trifluoromethylacetophenone content, calculate the oil phase intermediate trifluoromethylacetophenone oxime conversion rate is 73.6%;

[0081] Step b, concentrating the above-mentioned m-trifluoromethylacetophenone oxime oil phase under reduced pressure to a m-trifluoromethylacetophenone oxime content of 59%, cooling to 60°C, cooling to 0°C at a rate of 15°C / h, keeping warm for crystallization for 1.5h, filtering, washing, and drying to obtain 32.9g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.3%;

[0082] Step c, combining the filtrate and the washing liquid, concentrating under reduced pressure to a content of 55% of m-trifluoromethylacetophenone oxime, cooling to 60°C, cooling to 0°C at a rate of 15°C / h, keeping warm for crystallization for 1.5h, filtering, washing, and drying to obtain 9.00g of m-trifluoromethylacetophenone oxime, with an external standard content of 99.2%. The pure amount of the product obtained by the two crystallizations accounts for 72.4% of the theoretical product mass.

[0083] Comparative Example 1

[0084] This comparative example provides a post-treatment process for trifluoromethylacetophenone oxime, comprising the following steps:

[0085] Step a, add 280g of the above coupling reaction solution to the reactor, add 180mL of 20% hydrochloric acid solution, heat to reflux reaction for 120min, and generate NO x The gas was discharged after washing; the mixture was allowed to stand for separation, and the upper layer was a reddish-brown oil phase containing m-trifluoromethylacetophenone, and the lower layer was a yellowish-green aqueous phase (mainly copper chloride, hydroxylamine hydrochloride, hydrochloric acid, etc.). The oil phase was washed with a 20% sodium bicarbonate solution to a pH of 7-8, dried over anhydrous sodium sulfate, desolventized, and distilled under reduced pressure to obtain 91.06 g of light yellow m-trifluoromethylacetophenone, with a content of 99.5% and a yield of 85.2%;

[0086] Step b, add 37.8g (0.2mol) of m-trifluoromethylacetophenone, 120mL of methanol, and 16.8g (0.24mol) of hydroxylamine hydrochloride into a four-necked bottle, stir and heat to 50°C, add 8.2g (0.2mol) of sodium hydroxide in portions, keep warm for 1.5h, control the complete conversion of m-trifluoromethylacetophenone, recover methanol by reduced pressure distillation, add 100g of water, stir to dissolve the salt, cool to 5°C, filter, wash, and dry to obtain 38.8g of m-trifluoromethylacetophenone oxime, with a content of 99.4%, and a yield of 94.92% based on the charged m-trifluoromethylacetophenone, and a pure yield of 80.87% based on the charged m-trifluoromethylaniline by diazotization, coupling, acidolysis, and oximation.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A post-treatment process for m-trifluoromethylacetophenone oxime, characterized in that: The raw material is a coupling reaction liquid obtained by diazotization reaction and coupling reaction of m-trifluoromethylaniline, and the post-treatment process comprises the following steps: Step a, adding a copper complexing agent to the coupling reaction solution, stirring the reaction, standing, separating the liquids, and washing the obtained oil phase with alkali until it is neutral to obtain a m-trifluoromethylacetophenone oxime reaction solution; Wherein, the copper complexing agent is a sodium salt or potassium salt solution of diethylenetriaminepentaacetic acid, a sodium salt or potassium salt solution of ethylenediaminetetraacetic acid; Step b, concentrating the m-trifluoromethylacetophenone oxime reaction solution, cooling and crystallizing, solid-liquid separation, washing, and drying to obtain the m-trifluoromethylacetophenone oxime product.

2. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 1, characterized in that: In step a, the molar ratio of the alkali metal salt in the copper complexing agent to the copper ions in the copper catalyst added in the coupling reaction is 0.4 to 2:

1.

3. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 2, characterized in that: In step a, the molar ratio of the alkali metal salt in the copper complexing agent to the copper ions in the copper catalyst added in the coupling reaction is 0.5 to 0.8:

1.

4. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 1, characterized in that: In step a, the stirring reaction temperature is 40°C to 60°C, and the stirring reaction time is 20min to 60min; and / or In step a, the alkali washing adopts a sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution or potassium bicarbonate solution with a mass concentration of 10% to 30%; and / or The neutrality is pH 6-8.

5. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 1, characterized in that: In step b, the concentrated solution is concentrated to a concentration of 30% to 70% trifluoromethylacetophenone oxime; and / or In step b, the specific steps of cooling and crystallizing are: cooling to -10°C to 0°C at a rate of 10°C / h to 15°C / h, and keeping the temperature for crystallization for 1.5h to 3h.

6. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 1, characterized in that: The method also includes: step c: combining the washing liquid and the crystallization mother liquor obtained in step b, concentrating, cooling and crystallizing, solid-liquid separation, and washing to obtain the m-trifluoromethylacetophenone oxime product.

7. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 6, characterized in that: In step c, the concentrated solution is concentrated to a concentration of 40% to 60% trifluoromethylacetophenone oxime; and / or In step c, the specific steps of cooling and crystallizing are: cooling to -5°C to 0°C at a rate of 10°C / h to 15°C / h, and keeping the temperature for crystallization for 1h to 2h.

8. The post-treatment process of m-trifluoromethylacetophenone oxime according to claim 1, characterized in that: The steps for preparing the coupling reaction solution are as follows: S1, slowly drop m-trifluoromethylaniline into sulfuric acid or hydrochloric acid solution, drop sodium nitrite solution at -5℃~0℃, keep warm for reaction, filter and obtain diazonium salt solution; S2, uniformly mix the soluble copper salt, acetic acid, acetaldehyde oxime solution and toluene, dropwise add the diazonium salt solution at 0°C to 5°C, control the system pH to be 4 to 4.5, raise the temperature to 10°C to 20°C after the dropwise addition, keep the temperature for reaction, let stand, separate the liquids, and obtain the coupling reaction liquid.