Recycling method of 2, 6-dichloroacetophenone

Abstract

The invention belongs to the technical field of organic chemical synthesis, and relates to a method for recycling a compound, in particular to a method for recycling 2, 6-dichloroacetophenone. The invention relates to a method for recycling 2, 6-dichloroacetophenone, which comprises the following steps: taking waste containing 2, 6-dichloroacetophenone as a raw material, and reacting in the presence of a catalyst and inorganic alkali to generate m-dichlorobenzene. According to the method, the dichloroacetophenone waste is used as the raw material to recover the m-dichlorobenzene serving as the dichloroacetophenone synthesis raw material, equipment required by the process is conventional equipment, other solvents are not involved in the reaction, normal-pressure reaction is adopted in the process, the reaction temperature is lower, the process path is shorter, the operation is simple, the safety is high, waste resources are recycled, and the method is suitable for industrial production. The environmental pollution is effectively reduced, and the raw material consumption of the dichloroacetophenone production process is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic chemical synthesis and relates to a method for recycling a compound, in particular to a method for recycling 2,6-dichloroacetophenone. Background Art

[0002] 2,4-Dichloroacetophenone is an important fine chemical intermediate, which is widely used in the fields of medicine and pesticides. For example, 2,4-dichloroacetophenone can be used to synthesize the anti-deep fungal infection drugs fluconazole and itraconazole. It can also be used to prepare the intermediates of low-toxic, broad-spectrum, systemic fungicides such as pentoconazole, methiconazole, ethiconazole, propiconazole, etc., which are ω-bromo-2,4-dichloroacetophenone or ω-2,4-trichloroacetophenone. Both of them are also intermediates for the preparation of insecticide chlorfenapyr and herbicide diquat.

[0003] The main raw material for the synthesis of 2,4-dichloroacetophenone is m-dichlorobenzene. However, m-dichlorobenzene is expensive, and there is a great demand for it in production, and the production cost is high. At the same time, during the synthesis of 2,4-dichloroacetophenone, the crude 2,4-dichloroacetophenone obtained contains a large amount of isomer 2,6-dichloroacetophenone, and the purification methods of the crude 2,4-dichloroacetophenone mainly include distillation, rectification, crystallization and other methods, which can only separate the impurities in the crude 2,4-dichloroacetophenone, and its isomer 2,6-dichloroacetophenone is treated as three wastes, with high raw material consumption and serious waste of raw materials. Therefore, if this part of the isomer 2,6-dichloroacetophenone can be converted into m-dichlorobenzene for recycling, the utilization rate of the raw material m-dichlorobenzene can be improved, the yield of 2,4-dichloroacetophenone can be improved, and the waste of resources and cost investment can be reduced.

[0004] CN113307721A discloses a method for recycling 2,4-dichloroacetophenone isomer 2,6-dichloroacetophenone. The patent uses the bottom residue containing 2,6-dichloroacetophenone as raw material, adds sodium hydroxide and water, injects high-pressure air to pressurize to 1.5MPa, and then heats to 250°C for reaction. The reaction pressure is 4.5MPa. The temperature and pressure involved in the reaction are both high, the required energy consumption is high, the reaction risk is high, and the operation requirements are high. In view of the problems existing in the prior art, it is urgent to develop a reaction route with milder reaction conditions and higher safety. Summary of the invention

[0005] In order to solve the problems of waste of resources caused by ineffective treatment of by-products in the prior art and harsh conditions of the existing recovery methods, the present invention provides a method for recycling 2,6-dichloroacetophenone.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for recycling 2,6-dichloroacetophenone comprises the following steps: using waste containing 2,6-dichloroacetophenone as a raw material, reacting in the presence of a catalyst and an inorganic base to generate meta-dichlorobenzene, and recycling the meta-dichlorobenzene for the preparation of 2,4-dichloroacetophenone. The chemical reaction formula for recycling the waste containing 2,6-dichloroacetophenone is as follows:

[0008]

[0009] The waste containing 2,6-dichloroacetophenone is the waste generated in the process of synthesizing 2,4-dichloroacetophenone. The synthesis method of 2,4-dichloroacetophenone is: using m-dichlorobenzene and acetic anhydride as raw materials and aluminum chloride as a catalyst to synthesize crude 2,4-dichloroacetophenone, and the obtained crude 2,4-dichloroacetophenone is hydrolyzed, desolventized and distilled to obtain refined 2,4-dichloroacetophenone and dichloroacetophenone waste, and the dichloroacetophenone waste is the waste containing 2,6-dichloroacetophenone. In the waste containing 2,6-dichloroacetophenone, the mass proportion of 2,6-dichloroacetophenone is 92% to 95%, and the mass proportion of 2,4-dichloroacetophenone is 1% to 4%.

[0010] Furthermore, waste containing 2,6-dichloroacetophenone is used as a raw material, and a reaction is carried out under normal pressure, and meta-dichlorobenzene is generated in the presence of a catalyst and an inorganic base.

[0011] The catalyst is a high-efficiency catalyst and a phase transfer catalyst. The mass ratio of the waste containing 2,6-dichloroacetophenone to the high-efficiency catalyst is 1:0.001-0.01, and the mass ratio of the waste containing 2,6-dichloroacetophenone to the phase transfer catalyst is 1:0.001-0.01.

[0012] The high-efficiency catalyst is one or more of cuprous iodide, cuprous chloride, copper powder, copper acetate and copper sulfate.

[0013] The phase transfer catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, sodium dodecyl sulfate and crown ether.

[0014] The inorganic base is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate and cesium hydroxide; the mass ratio of the waste containing 2,6-dichloroacetophenone to the inorganic base is 1:0.2-0.5.

[0015] The reaction temperature is 80-150° C., and the reaction time is 2-10 hr.

[0016] The post-processing steps after the reaction are as follows:

[0017] After the reaction is completed, the temperature is lowered to 20-40° C., a 2% to 5% hydrochloric acid aqueous solution is added to adjust the pH to neutral, the mixture is allowed to stand for stratification, deionized water is added to the organic phase for washing once, the mixture is allowed to stand for stratification, and the meta-dichlorobenzene product is obtained.

[0018] Compared with the existing technology, it has the following characteristics:

[0019] The present invention provides a method for recycling 2,6-dichloroacetophenone, which is a production process in which dichloroacetophenone waste is used as a raw material, reacts with a solid base in the presence of a catalyst under normal pressure, and is recycled and reused to convert it into raw material meta-dichlorobenzene. The reaction has the following advantages:

[0020] (1) The present invention is carried out under normal pressure, and the reaction temperature is low. The equipment required for the process is conventional equipment, and the reaction cost is low.

[0021] (2) The present invention adds a high-efficiency catalyst and a phase transfer catalyst to increase the reaction rate, mild reaction conditions, a shorter reaction route, and improve the safety and economy of the recovery technology.

[0022] (3) No other solvents are involved in the reaction process, which avoids waste of resources and greatly saves production costs.

[0023] (4) The post-processing steps of the present invention are simple. After washing with water and standing for stratification, the meta-xylene raw material with a purity that can be directly used for industrial production can be obtained.

[0024] The present invention realizes the recycling of waste resources, effectively reduces environmental pollution, significantly reduces the raw material consumption of the 2,4-dichloroacetophenone production process, and improves the yield of the 2,4-dichloroacetophenone synthesis process. The present invention is a clean and efficient production process. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be described in detail below, but the present invention is not limited to the following description. In the following examples and comparative examples, the waste containing 2,6-dichloroacetophenone comes from the waste generated by the synthesis of 2,4-dichloroacetophenone from meta-dichlorobenzene, specifically: meta-dichlorobenzene and acetic anhydride are used as raw materials, and aluminum chloride is used as a catalyst to synthesize 2,4-dichloroacetophenone crude product, and the obtained 2,4-dichloroacetophenone crude product is hydrolyzed, desolventized, and distilled to obtain refined 2,4-dichloroacetophenone and dichloroacetophenone waste; the dichloroacetophenone waste contains 2,4-dichloroacetophenone, 2,6-dichloroacetophenone and other impurities, and the dichloroacetophenone waste is the waste containing 2,6-dichloroacetophenone.

[0026] The specific implementation of the technical solution of the present invention is described in detail below, but the present invention is not limited to the following description:

[0027] The present invention is described below in conjunction with specific embodiments.

[0028] Embodiment 1:

[0029] A method for recycling 2,4-dichloroacetophenone isomer 2,6-dichloroacetophenone comprises the following steps:

[0030] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 7.8 g of 2,4-dichloroacetophenone and 711.5 g of 2,6-dichloroacetophenone; 170 g of solid sodium hydroxide, 1 g of cuprous chloride and 2 g of tetrabutylammonium bromide are added, and the reaction is carried out under normal pressure. The mixture is stirred, heated to 130-140° C., kept warm for 8 hours, cooled to 20-40° C., 2% aqueous hydrochloric acid solution is added to adjust the pH to neutral, and the mixture is allowed to stand for stratification. 150 g of deionized water is added to the organic phase, and the mixture is allowed to stand for stratification to obtain 535.5 g of m-dichlorobenzene product with a content of 98.2%.

[0031] Embodiment 2:

[0032] A method for recycling 2,4-dichloroacetophenone isomer 2,6-dichloroacetophenone comprises the following steps:

[0033] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 13.5 g of 2,4-dichloroacetophenone and 710.9 g of 2,6-dichloroacetophenone; 250 g of potassium hydroxide, 5 g of cuprous chloride and 2 g of tetrabutylammonium chloride are added, and the reaction is carried out under normal pressure, stirred, heated to 110-120° C., kept warm for 6 hours, cooled to 20-40° C., 2% hydrochloric acid aqueous solution is added to adjust the pH to neutral, allowed to stand for stratification, 150 g of deionized water is added to the organic phase, washed once, allowed to stand for stratification, and 545.7 g of meta-dichlorobenzene product with a content of 98.5% is obtained.

[0034] Embodiment 3:

[0035] A method for recycling 2,4-dichloroacetophenone isomer 2,6-dichloroacetophenone comprises the following steps:

[0036] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 10.7 g of 2,4-dichloroacetophenone and 709.3 g of 2,6-dichloroacetophenone; 300 g of potassium hydroxide, 4 g of cuprous iodide and 5 g of sodium dodecyl sulfate are added, and the reaction is carried out under normal pressure, and the temperature is raised to 90-100° C., and the reaction is kept at this temperature for 10 hours, and the temperature is lowered to 20-40° C., and a 2% hydrochloric acid aqueous solution is added to adjust the pH to neutral, and the mixture is allowed to stand for stratification, and 150 g of deionized water is added to the organic phase for washing once, and the mixture is allowed to stand for stratification to obtain 540 g of meta-dichlorobenzene product with a content of 98.7%.

[0037] Embodiment 4:

[0038] A method for recycling 2,4-dichloroacetophenone isomer 2,6-dichloroacetophenone comprises the following steps:

[0039] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 20.1 g of 2,4-dichloroacetophenone and 704.2 g of 2,6-dichloroacetophenone; 230 g of potassium hydroxide, 6 g of cuprous chloride and 6 g of crown ether are added, and the reaction is carried out under normal pressure, stirred, heated to 120-130° C., kept warm for 3 hours, cooled to 20-40° C., 2% hydrochloric acid aqueous solution is added to adjust the pH to neutral, allowed to stand for stratification, 150 g of deionized water is added to the organic phase, washed once, allowed to stand for stratification, and 542.5 g of m-dichlorobenzene product with a content of 98.6% is obtained.

[0040] Comparative Example 1:

[0041] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 13.1 g of 2,4-dichloroacetophenone and 708.2 g of 2,6-dichloroacetophenone; 230 g of potassium hydroxide and 6 g of aluminum chloride are added, and the reaction is carried out under normal pressure, stirred, heated to 120-130° C., kept warm for 3 hours, cooled to 20-40° C., 2% hydrochloric acid aqueous solution is added to adjust the pH to neutral, allowed to stand for stratification, 150 g of deionized water is added to the organic phase, washed once, allowed to stand for stratification, and 538.6 g of meta-dichlorobenzene product with a content of 78.3% is obtained.

[0042] Comparative Example 2:

[0043] 750 g of waste containing 2,6-dichloroacetophenone was added into a reaction bottle, wherein the waste contained 13.1 g of 2,4-dichloroacetophenone and 706.5 g of 2,6-dichloroacetophenone; 230 g of potassium hydroxide, 7.5 g of aluminum chloride and 7.5 g of tetrabutylammonium bromide were added, and the reaction was carried out under normal pressure with stirring. The temperature was raised to 120-130° C. and the reaction was kept warm for 3 hours. The temperature was lowered to 20-40° C., a 2% aqueous hydrochloric acid solution was added to adjust the pH to neutral, and the mixture was allowed to stand for stratification. 150 g of deionized water was added to the organic phase for washing once, and the mixture was allowed to stand for stratification to obtain 518.5 g of m-dichlorobenzene product with a content of 84.6%.

[0044] Comparative Example 3:

[0045] 750 g of waste containing 2,6-dichloroacetophenone is added into a reaction bottle, wherein the waste contains 14.4 g of 2,4-dichloroacetophenone and 708.2 g of 2,6-dichloroacetophenone; 170 g of sodium hydroxide, 7.5 g of nickel chloride and 7.5 g of tetrabutylammonium bromide are added, and the reaction is carried out under normal pressure, stirred, heated to 120-130° C., kept warm for 3 hours, cooled to 20-40° C., 2% hydrochloric acid aqueous solution is added to adjust the pH to neutral, allowed to stand for stratification, 150 g of deionized water is added to the organic phase, washed once, allowed to stand for stratification, and 523.8 g of m-dichlorobenzene product with a content of 80.3% is obtained.

[0046] The content of the dichlorobenzene product obtained by the recovery method of the embodiment of the present application reaches more than 98.5%, which can basically meet the requirements for the recovery and use of production raw materials. The content of the dichlorobenzene products obtained by the recovery method of the comparative example is less than 85%, which does not reach the purity that can be directly used as a chemical product, and the amount of meta-dichlorobenzene product collected is significantly lower than that of the embodiment. Therefore, the recovery method of the present invention can recover a dichlorobenzene product with a purity of more than 98.5% under relatively mild reaction conditions under normal pressure.

[0047] The above examples are only for illustrating the technical concept and technical features of the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recycling 2,6-dichloroacetophenone, characterized in that: Using waste containing 2,6-dichloroacetophenone as raw material, meta-dichlorobenzene is generated by reaction in the presence of a catalyst and an inorganic base.

2. The recycling method according to claim 1, characterized in that: The waste containing 2,6-dichloroacetophenone is used as a raw material, and the reaction is carried out under normal pressure, and meta-dichlorobenzene is generated in the presence of a catalyst and an inorganic base.

3. The recycling method according to claim 2, characterized in that: The catalyst is a high-efficiency catalyst and a phase transfer catalyst. The mass ratio of the waste containing 2,6-dichloroacetophenone to the high-efficiency catalyst is 1:0.001-0.01, and the mass ratio of the waste containing 2,6-dichloroacetophenone to the phase transfer catalyst is 1:0.001-0.

01.

4. The recycling method according to claim 3, characterized in that: The high-efficiency catalyst is one or more of cuprous iodide, cuprous chloride, copper powder, copper acetate and copper sulfate.

5. The recycling method according to claim 4, characterized in that: The phase transfer catalyst is one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, sodium dodecyl sulfate and crown ether.

6. The recycling method according to claim 5, characterized in that: The inorganic base is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate and cesium hydroxide; the mass ratio of the waste containing 2,6-dichloroacetophenone to the inorganic base is 1:0.2-0.

5.

7. The recycling method according to claim 1, characterized in that: The reaction temperature is 80-150° C., and the reaction time is 2-10 hr.

Images