A method for efficiently synthesizing 3-chloropropiophenone

Abstract

The application relates to the technical field of organic synthesis, and particularly discloses a method for efficiently synthesizing 3-chlorophenylacetone. The method comprises the following steps: 1) carrying out an alkaline hydrolysis reaction on m-chlorobenzonitrile, and then carrying out an acidification reaction to prepare m-chlorobenzoic acid; 2) carrying out a condensation reaction on the m-chlorobenzoic acid obtained in the step 1) and propionic acid under the action of a catalyst, then carrying out a decarboxylation reaction by heating, and then removing residual propionic acid by heating; when distillate starts to appear, the distillate is absorbed by a solvent to obtain an absorption liquid, and then the absorption liquid is cooled and crystallized to obtain 3-chlorophenylacetone. The synthesis method has the advantages of high efficiency and low cost.

Description

Technical Field

[0001] This application relates to the field of organic synthesis technology, and more specifically, to a method for the efficient synthesis of 3-chlorophenylacetone. Background Technology

[0002] 3-Chlorophenylacetone is an important pharmaceutical chemical intermediate, existing as white or yellow crystals. As a derivative of phenylacetone, 3-chlorophenylacetone possesses similar physicochemical properties and can undergo various chemical transformation reactions. It has wide applications in organic synthetic chemistry, primarily in the synthesis of psychotropic drugs.

[0003] The currently mature method for synthesizing 3-chlorophenylacetone utilizes acylation and chlorination reactions. First, acetone is obtained as an intermediate through acylation, and then 3-chlorophenylacetone is obtained through chlorination. The acylation reaction typically uses benzene and propionyl chloride as raw materials, requiring 1,2-dichloroethane as a solvent and aluminum trichloride as a catalyst. However, 1,2-dichloroethane is flammable and highly toxic, and aluminum trichloride readily absorbs water and is prone to hydrolysis during the reaction. Furthermore, the acylation reaction generates large amounts of hydrogen chloride gas and acidic wastewater.

[0004] Chinese patent application CN117886683A discloses a method for preparing m-chlorophenylacetone. The method involves introducing nitrogen gas into an acylation reactor to replace the air inside the reactor, thereby reducing the humidity level of the gas inside the reactor until it is below 5%. Then, gas valves one and two are closed. This method avoids exposing the acylation reaction raw materials to air and prevents the flocculent precipitation that occurs during the hydrolysis of aluminum trichloride. However, it does not fundamentally solve the shortcomings of the acylation and chlorination reaction routes.

[0005] Another existing method for synthesizing 3-chlorophenylacetone uses m-chlorobenzonitrile as a raw material. It involves reacting magnesium metal in tetrahydrofuran to generate a Grignard reagent, which then undergoes a nucleophilic addition reaction between ethyl magnesium bromide and m-chlorobenzonitrile. Hydrolysis with hydrochloric acid is then performed to obtain 3-chlorophenylacetone. This method eliminates the need for acylation and chlorination reactions, but the Grignard reagent is difficult to prepare, has low production efficiency, and is expensive, hindering industrial production. Therefore, exploring and finding a more efficient and cost-effective method for synthesizing 3-chlorophenylacetone remains a pressing issue. Summary of the Invention

[0006] To further improve the synthesis efficiency of 3-chlorophenylacetone, this application provides a method for the efficient synthesis of 3-chlorophenylacetone.

[0007] This application provides a method for the efficient synthesis of 3-chlorophenylacetone, employing the following technical solution:

[0008] A method for the efficient synthesis of 3-chlorophenylacetone includes the following steps:

[0009] 1) Prepare m-chlorobenzoic acid by first subjecting m-chlorobenzonitrile to an alkaline hydrolysis reaction and then to an acidification reaction;

[0010] 2) The m-chlorobenzoic acid obtained in step 1) is first condensed with propionic acid under the action of a catalyst, and then the temperature is raised to carry out a decarboxylation reaction. Then the temperature is raised to remove the remaining propionic acid. When distillate begins to appear, the distillate is absorbed with a solvent to obtain an absorbent. The absorbent is then cooled and crystallized to obtain 3-chlorophenylacetone.

[0011] Preferably, step 1) further includes at least one of the following technical features:

[0012] 11) The alkali used in the alkaline hydrolysis reaction is one of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate;

[0013] 12) The temperature of the alkaline hydrolysis reaction is 75-90℃;

[0014] 13) The acidification reaction is carried out at a temperature of 20-35℃;

[0015] 14) The acid used in the acidification reaction is hydrochloric acid or sulfuric acid;

[0016] 15) In the alkaline hydrolysis reaction, a quaternary ammonium base and dimethyl sulfoxide are also added.

[0017] Preferably, the quaternary ammonium base is one or more of tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphine hydroxide.

[0018] Preferably, the molar ratio of the quaternary ammonium base to dimethyl sulfoxide is (0.08-0.2):1.

[0019] Preferably, step 2) further includes at least one of the following technical features:

[0020] 21) The molar ratio of m-chlorobenzoic acid to propionic acid is (0.1-0.2):1;

[0021] 22) The condensation reaction temperature is 120-135℃;

[0022] 23) The condensation reaction time is 6-8 hours;

[0023] 24) The decarboxylation reaction time is 1-2 hours;

[0024] 25) The decarboxylation reaction temperature is 200-280℃;

[0025] 26) The catalyst includes a first catalyst and a second catalyst, wherein the first catalyst includes iron powder and cobalt oxide;

[0026] 27) The mass ratio of m-chlorobenzoic acid to the catalyst is 1:(0.2-25);

[0027] 28) The solvent is ethanol or ethyl acetate.

[0028] Preferably, the first catalyst is composed of iron powder and cobalt oxide in a mass ratio of 1:(0.2-0.3).

[0029] Preferably, the second catalyst is prepared by the following steps:

[0030] S1: Prepare a base solution by mixing hexadecyltrimethylammonium bromide, carrageenan, and deionized water. Then add sodium silicate solution to the base solution and age it at 120-135℃. Filter and wash to obtain a solid. Calcine the solid to obtain a precursor.

[0031] S2: Dissolve aluminum chloride, urea, and chloroplatinic acid in anhydrous ethanol, then add the precursor material and stir evenly. Then heat and stir continuously until the ethanol evaporates to dryness, and calcine the resulting powder to obtain the final product.

[0032] Preferably, in step S1, the mass ratio of hexadecyltrimethylammonium bromide, carrageenan, and deionized water is (0.17-0.19):(0.05-0.1):1.

[0033] Preferably, in step S2, the mass ratio of aluminum chloride, urea, and chloroplatinic acid is (4.5-5):(0.1-0.25):1.

[0034] Preferably, in step S2, the mass ratio of aluminum chloride to precursor is (0.015-0.03):1.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application uses m-chlorobenzonitrile as a raw material, which first undergoes alkaline hydrolysis and acidification, followed by a condensation reaction and decarboxylation reaction with propionic acid. The synthesis process does not require acylation or chlorination reactions, and does not generate toxic or harmful gases or acidic wastewater. Furthermore, the auxiliary chemicals used in the synthesis process of this application are inexpensive and readily available, resulting in low production costs and suitability for industrial production.

[0037] 2. This application incorporates a first catalyst and a second catalyst during the condensation reaction. The iron powder and cobalt oxide in the first catalyst lower the activation energy and reaction temperature, significantly improving the condensation reaction efficiency and product yield. Furthermore, the second catalyst uses a base solution prepared with hexadecyltrimethylammonium bromide and carrageenan as composite components. After adding sodium silicate and aging and calcining, the resulting precursor has a large specific surface area. This precursor is then combined with aluminum chloride, urea, and chloroplatinic acid, loading aluminum and platinum elements into the precursor's pore structure. During the reaction, these elements activate CO bonds and other related covalent bonds, promoting proton transfer and improving the decarboxylation reaction efficiency. In addition, the addition of urea enhances the ordered pore structure of the precursor and introduces nitrogen vacancies, increasing the contact area and mass transfer efficiency between the reactants and the second catalyst, as well as the number of active sites, thereby improving the overall synthesis efficiency.

[0038] 3. This application uses a combination of a first catalyst and a second catalyst. In the condensation reaction stage, the first catalyst dominates. In the decarboxylation stage, as the reaction temperature is further increased, a certain amount of free hot electrons will be generated on the surface of the iron powder and cobalt oxide particles in the first catalyst. This will promote the adsorption and reaction of the reactants in the pore structure of the second precursor, resulting in higher yield and selectivity. At the same time, the reaction temperature is reduced, and the entire reaction process is carried out more efficiently. Attached Figure Description

[0039] Figure 1 This is a TEM image of the second catalyst in Example 2 of this application.

[0040] Figure 2 This is a TEM image of the second catalyst in Example 3 of this application.

[0041] Figure 3 This is a schematic diagram of the catalytic activity and stability data of the second catalyst in Examples 2 and 3 of this application. Detailed Implementation

[0042] The present application will be further described in detail below with reference to the embodiments.

[0043] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0044] Through extensive experimental research, the inventors of this application have provided a new and efficient method for synthesizing 3-chlorophenylacetone, which has the advantages of high yield, low cost, simple route, high reaction efficiency, and economic and environmental benefits.

[0045] The method for the efficient synthesis of 3-chlorophenylacetone disclosed in this application includes the following steps:

[0046] 1) Prepare m-chlorobenzoic acid by first subjecting m-chlorobenzonitrile to an alkaline hydrolysis reaction and then to an acidification reaction;

[0047] 2) The m-chlorobenzoic acid obtained in step 1) is first condensed with propionic acid under the action of a catalyst, and then the temperature is raised to carry out a decarboxylation reaction. Then the temperature is raised to remove the remaining propionic acid. When distillate begins to appear, the distillate is absorbed with a solvent to obtain an absorbent. The absorbent is then cooled and crystallized to obtain 3-chlorophenylacetone.

[0048] Preferably, step 1) further includes at least one of the following technical features:

[0049] 11) The alkali used in the alkaline hydrolysis reaction is one of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate;

[0050] 12) The temperature of the alkaline hydrolysis reaction is 75-90℃;

[0051] 13) The acidification reaction is carried out at a temperature of 20-35℃;

[0052] 14) The acid used in the acidification reaction is hydrochloric acid or sulfuric acid;

[0053] 15) In the alkaline hydrolysis reaction, a quaternary ammonium base and dimethyl sulfoxide are also added.

[0054] In some specific embodiments, in step 1), the alkali used in the alkaline hydrolysis reaction is one of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate. For example, sodium hydroxide is generally preferred in the alkaline hydrolysis reaction. The temperature of the alkaline hydrolysis reaction is 75-90℃, for example, 75-80℃, 80-85℃, or 85-90℃. Generally, a temperature of 85℃ is more effective. The temperature of the acidification reaction is 20-35℃, for example, 20℃, 25℃, 30℃, or 35℃. The quaternary ammonium base is one or more of tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphine hydroxide. Generally, tetrabutylphosphine hydroxide is preferred as the quaternary ammonium base to obtain better experimental results. In some embodiments, the molar ratio of the quaternary ammonium base to dimethyl sulfoxide can be (0.08-0.1):1, (0.1-0.12):1, (0.12-0.15):1, (0.15-0.175):1, or (0.175-0.2):1. More preferably, the molar ratio of the quaternary ammonium base to dimethyl sulfoxide can be 0.08:1, 0.09:1, 0.1:1, 0.12:1, 0.13:1, 0.15:1, 0.16:1, 0.175:1, 0.19:1, or 0.2:1. Generally, a molar ratio of 0.15:1 for the quaternary ammonium base to dimethyl sulfoxide yields better results.

[0055] Preferably, step 2) further includes at least one of the following technical features:

[0056] 21) The molar ratio of m-chlorobenzoic acid to propionic acid is (0.1-0.2):1;

[0057] 22) The condensation reaction temperature is 120-135℃;

[0058] 23) The condensation reaction time is 6-8 hours;

[0059] 24) The decarboxylation reaction time is 1-2 hours;

[0060] 25) The decarboxylation reaction temperature is 200-280℃;

[0061] 26) The catalyst includes a first catalyst and a second catalyst, wherein the first catalyst includes iron powder and cobalt oxide;

[0062] 27) The mass ratio of m-chlorobenzoic acid to the catalyst is 1:(0.2-25);

[0063] 28) The solvent is ethanol or ethyl acetate.

[0064] In some specific embodiments, the molar ratio of m-chlorobenzoic acid to propionic acid can be (0.1-0.12):1, (0.12-0.14):1, (0.14-0.16):1, (0.16-0.18):1, or (0.18-0.2):1. More preferably, the molar ratio of m-chlorobenzoic acid to propionic acid can be 0.1:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, or 0.2:1. Generally, a molar ratio of 0.16:1 for m-chlorobenzoic acid to propionic acid is more effective.

[0065] In some specific embodiments, the condensation reaction temperature can be 120-125℃, 125-130℃, or 130-135℃, and more preferably, for example, 120℃, 125℃, 128℃, 130℃, 132℃, or 135℃.

[0066] Preferably, the first catalyst is composed of iron powder and cobalt oxide in a mass ratio of 1:(0.2-0.3). More preferably, the average particle size of the iron powder is 200-500 nm.

[0067] Preferably, the second catalyst is prepared by the following steps:

[0068] S1: Prepare a base solution by mixing hexadecyltrimethylammonium bromide, carrageenan, and deionized water. Then add sodium silicate solution to the base solution and age it at 120-135℃. Filter and wash to obtain a solid. Calcine the solid to obtain a precursor.

[0069] S2: Dissolve aluminum chloride, urea, and chloroplatinic acid in anhydrous ethanol, then add the precursor material and stir evenly. Then heat and stir continuously until the ethanol evaporates to dryness, and calcine the resulting powder to obtain the final product.

[0070] In some specific embodiments, in step S1, the mass ratio of hexadecyltrimethylammonium bromide, carrageenan, and deionized water can be (0.17-0.19):(0.05-0.1):1, (0.18-0.19):(0.05-0.07):1, (0.17-0.19):(0.05-0.08):1, and more preferably, 0.17:0.05:1, 0.17:0.07:1, 0.17:0.08:1, 0.17:0.09:1, or 0.18:0.05:1. The following ratios are suggested: 0.18:0.06:1, 0.18:0.07:1, 0.18:0.08:1, 0.18:0.09:1, 0.17:0.1:1, 0.18:0.1:1, 0.19:0.05:1, 0.19:0.06:1, 0.19:0.07:1, 0.19:0.08:1, 0.19:0.09:1, and 0.19:0.1:1. Under normal circumstances, a mass ratio of hexadecyltrimethylammonium bromide, carrageenan, and deionized water of 0.19:0.07:1 is more effective.

[0071] In some specific embodiments, in step S2, the mass ratio of aluminum chloride, urea, and chloroplatinic acid can be (4.5-4.8):(0.1-0.25):1, (4.5-4.8):(0.1-0.15):1, (4.5-5):(0.1-0.15):1, (4.5-5):(0.1-0.2):1, (4.5-4.8):(0.1-0.25):1, (4.8-5):(0.1-0.25):1, (4.8-5):(0.1-0.25):1, (4.8-5):(0.1-0.25):1. ):1、(4.8-5):(0.1-0.15):1, for example, it can be 4.5:0.1:1, 4.5:0.15:1, 4.5:0.2:1, 4.5:0.25:1, 4.8:0.1:1, 4.8:0.15:1, 4.8:0.2:1, 4.8:0.25:1, 5:0.1:1, 5:0.15:1, 5:0.2:1, 5:0.25:1. Generally, the mass ratio of aluminum chloride, urea and chloroplatinic acid is better when it is 4.6:0.2:1.

[0072] In some specific embodiments, in step S2, the mass ratio of aluminum chloride to the precursor can be (0.015-0.018):1, (0.018-0.02):1, (0.02-0.025):1, (0.025-0.027):1, or (0.027-0.03):1. Preferably, it can be 0.015:1, 0.017:1, 0.019:1, 0.02:1, 0.022:1, 0.025:1, 0.027:1, 0.029:1, or 0.03:1. Under normal circumstances, a mass ratio of aluminum chloride to the precursor of 0.02:1 is more effective.

[0073] In some specific embodiments, in step S1, the molar ratio of sodium silicate to hexadecyltrimethylammonium bromide is (20-25):1. Generally, a molar ratio of sodium silicate to hexadecyltrimethylammonium bromide of 22:1 is more effective. Example

[0074] The method for efficiently synthesizing 3-chlorophenylacetone in this embodiment includes the following steps:

[0075] 1) Add 0.2 mol of m-chlorobenzonitrile to a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, then add 0.75 mol of sodium hydroxide and 200 g of glycerol. Heat to 85 °C for alkaline hydrolysis reaction for 5 h, then cool to 25 °C and add 30% hydrochloric acid for acidification reaction. Filter, wash with deionized water to obtain a white solid, and dry to obtain m-chlorobenzoic acid with a yield of 95.8% and a purity of 99.1%.

[0076] 2) Add 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 7.2 g of catalyst to a four-necked flask equipped with an electric stirrer, thermometer, and condenser. Stir until homogeneous and heat to 135 °C to carry out a condensation reaction. After 7 h of reaction, distill off excess propionic acid. Then heat to 280 °C to carry out a decarboxylation reaction. When gaseous and liquid distillates begin to appear, absorb the distillate with ethanol to obtain an absorbent. Stop the reaction when no distillate is produced after 1.5 h. Then distill the absorbent to remove ethanol. After cooling and crystallization, a white solid product is obtained. Recrystallize the white solid product with ethanol to obtain 3-chlorophenylacetone with a yield of 71.5% and a purity of 99.3%.

[0077] The catalyst consists of 6g of iron powder and 1.2g of cobalt oxide, with the iron powder having an average particle size of 500nm. Example

[0078] The method for efficiently synthesizing 3-chlorophenylacetone in this embodiment includes the following steps:

[0079] 1) Add 0.2 mol of m-chlorobenzonitrile to a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, then add 0.75 mol of sodium hydroxide and 200 g of glycerol. Heat to 85 °C for alkaline hydrolysis reaction for 5 h, then cool to 25 °C and add 30% hydrochloric acid for acidification reaction. Filter, wash with deionized water to obtain a white solid, and dry to obtain m-chlorobenzoic acid with a yield of 95.5% and a purity of 98.9%.

[0080] 2) Add 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 9 g of catalyst to a four-necked flask equipped with an electric stirrer, thermometer, and condenser. Stir until homogeneous and heat to 135°C to carry out a condensation reaction. After 7 hours of reaction, distill off excess propionic acid. Then, heat to 255°C to carry out a decarboxylation reaction. When gaseous and liquid distillates begin to appear, absorb the distillate with ethanol to obtain an absorbent. Stop the reaction when no distillate is produced after 1.5 hours. Then, distill the absorbent to remove ethanol. After cooling and crystallization, a white solid product is obtained. Recrystallize the white solid product with ethanol to obtain 3-chlorophenylacetone with a yield of 75.2% and a purity of 99.5%.

[0081] The catalyst consists of 7.2g of a first catalyst and 1.8g of a second catalyst. The first catalyst consists of 6g of iron powder and 1.2g of cobalt oxide. The average particle size of the iron powder is 500nm.

[0082] The second catalyst in this embodiment is prepared using the following steps:

[0083] S1: 7.6g of cetyltrimethylammonium bromide and 40g of deionized water were mixed evenly to prepare a base solution. Then, sodium silicate solution was slowly added to the base solution. The sodium silicate solution was prepared by dissolving 55.8g of sodium silicate nonahydrate in 80g of deionized water. After the sodium silicate solution was added dropwise, the pH value was adjusted to 11. Then, the temperature was raised to 125℃ and aged for 24h. After filtration, the solid was washed with deionized water until neutral to obtain a solid. The solid was placed in a muffle furnace and heated to 600℃ at a heating rate of 1.5℃ / min. It was calcined in air atmosphere for 5h to obtain the precursor material.

[0084] S2: Dissolve aluminum chloride in anhydrous ethanol, then add the precursor and stir evenly. Control the mass ratio of aluminum chloride to precursor to be 0.02:1. Then heat to 60℃ for hydrothermal reaction. After the ethanol evaporates, transfer the resulting powder to a muffle furnace and heat to 550℃ at a heating rate of 2℃ / min. Calcine in air for 6 hours to obtain the final product. Example

[0085] The method for efficiently synthesizing 3-chlorophenylacetone in this embodiment includes the following steps:

[0086] 1) Add 0.2 mol of m-chlorobenzonitrile to a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, then add 0.75 mol of sodium hydroxide and 200 g of glycerol. Heat to 85 °C for alkaline hydrolysis reaction for 5 h, then cool to 25 °C and add 30% hydrochloric acid for acidification reaction. Filter, wash with deionized water to obtain a white solid, and dry to obtain m-chlorobenzoic acid with a yield of 95.6% and a purity of 99%.

[0087] 2) Add 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 9 g of catalyst to a four-necked flask equipped with an electric stirrer, thermometer, and condenser. Stir until homogeneous and heat to 135°C to carry out a condensation reaction. After 7 hours of reaction, distill off excess propionic acid. Then, heat to 220°C to carry out a decarboxylation reaction. When gaseous and liquid distillates begin to appear, absorb the distillate with ethanol to obtain an absorbent. Stop the reaction when no distillate is produced after 1.5 hours. Then, distill the absorbent to remove ethanol. After cooling and crystallization, a white solid product is obtained. Recrystallize the white solid product with ethanol to obtain 3-chlorophenylacetone with a yield of 88.7% and a purity of 99.6%.

[0088] The catalyst consists of 7.2g of a first catalyst and 1.8g of a second catalyst. The first catalyst consists of 6g of iron powder and 1.2g of cobalt oxide. The average particle size of the iron powder is 500nm.

[0089] The second catalyst in this embodiment is prepared using the following steps:

[0090] S1: 7.6g hexadecyltrimethylammonium bromide, 2.8g carrageenan, and 40g deionized water were mixed evenly to prepare a base solution. Then, sodium silicate solution was slowly added to the base solution. The sodium silicate solution was prepared by dissolving 55.8g sodium silicate nonahydrate in 80g deionized water. After the sodium silicate solution was added dropwise, the pH value was adjusted to 11. Then, the temperature was raised to 125℃ and aged for 24h. After filtration, the solid was washed with deionized water until neutral to obtain a solid. The solid was placed in a muffle furnace and heated to 600℃ at a heating rate of 1.5℃ / min. It was calcined in air atmosphere for 5h to obtain the precursor material.

[0091] S2: Dissolve aluminum chloride, urea, and chloroplatinic acid in anhydrous ethanol, then add the precursor and stir evenly. Control the mass ratio of aluminum chloride, urea, and chloroplatinic acid to be 4.6:0.2:1. Then raise the temperature to 60℃ for hydrothermal reaction. After the ethanol evaporates, transfer the resulting powder to a muffle furnace and raise the temperature to 550℃ at a heating rate of 2℃ / min. Calcine in air atmosphere for 6 hours to obtain the final product.

[0092] Performance testing

[0093] 1. The second catalysts from Examples 2 and 3 were subjected to transmission electron microscopy (TEM) testing. The test results are as follows: Figure 1 and Figure 2 As shown, the second catalyst prepared in Example 3 has a better pore structure morphology, a larger specific surface area and catalytic activity. The second catalyst in Example 2 has a larger proportion of agglomeration, a worse pore structure morphology than that in Example 3, and a lower mass transfer efficiency.

[0094] 2. The catalysts from Examples 2 and 3 were used to repeat the experiments according to the methods described in Examples 2 and 3. After each experiment, the catalyst was recovered and washed with hot methanol solution. The catalytic activity and stability of the catalyst were tested, and the results are as follows: Figure 3 As shown, the horizontal axis represents the number of experiments (s), and the vertical axis represents the yield of 3-chlorophenylacetone (%). Figure 3 It can be seen that although the activity of Example 3 decreased, the reason for the decrease may be that the catalyst lost some mass during recycling, and the overall catalytic activity of the catalyst remained stable.

[0095] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for the efficient synthesis of 3-chlorophenylacetone, characterized in that, The process includes the following steps: 1) m-chlorobenzonitrile is first subjected to an alkaline hydrolysis reaction, and then an acidification reaction is carried out to prepare m-chlorobenzoic acid, wherein a quaternary ammonium base and dimethyl sulfoxide are added in the alkaline hydrolysis reaction; 2) the m-chlorobenzoic acid obtained in step 1) is first subjected to a condensation reaction with propionic acid under the action of a catalyst, and then a decarboxylation reaction is carried out by heating. Then, the remaining propionic acid is removed by heating. When distillate begins to appear, the distillate is absorbed by a solvent to obtain an absorbent liquid. The absorbent liquid is then cooled and crystallized to obtain 3-chlorophenylacetone. The catalyst includes a first catalyst and a second catalyst. The first catalyst includes iron powder and cobalt oxide, and the first catalyst is composed of iron powder and cobalt oxide in a mass ratio of 1:(0.2-0.3). The second catalyst is prepared by the following steps: S1: Hexadecyltrimethylammonium bromide, carrageenan, and deionized water are mixed evenly to prepare a base solution. Then, sodium silicate solution is added to the base solution, and the reaction is carried out at 120-135℃. After filtration and washing, a solid is obtained. The solid is then calcined to obtain a precursor. S2: Aluminum chloride, urea, and chloroplatinic acid are dissolved in anhydrous ethanol. Then, the precursor is added and stirred evenly. The mixture is then heated and stirred continuously. After the ethanol is evaporated, the resulting powder is calcined to obtain the catalyst.

2. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 1, characterized in that, Step 1) further includes at least one of the following technical features: 11) the alkali used in the alkaline hydrolysis reaction is one of potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate; 12) the temperature of the alkaline hydrolysis reaction is 75-90℃; 13) the temperature of the acidification reaction is 20-35℃; 14) the acid used in the acidification reaction is hydrochloric acid or sulfuric acid.

3. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 2, characterized in that, The quaternary ammonium base is one or more of tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphine hydroxide.

4. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 2, characterized in that, The molar ratio of the quaternary ammonium base to dimethyl sulfoxide is (0.08-0.2):

1.

5. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 1, characterized in that, Step 2) further includes at least one of the following technical features: 21) the molar ratio of m-chlorobenzoic acid to propionic acid is (0.1-0.2):1; 22) the condensation reaction temperature is 120-135℃; 23) the condensation reaction time is 6-8h; 24) the decarboxylation reaction time is 1-2h; 25) the decarboxylation reaction temperature is 200-280℃; 26) the mass ratio of m-chlorobenzoic acid to catalyst is 1:(0.2-25); 28) the solvent is ethanol or ethyl acetate.

6. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 5, characterized in that, In step S1, the mass ratio of hexadecyltrimethylammonium bromide, carrageenan, and deionized water is (0.17-0.19):(0.05-0.1):

1.

7. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 5, characterized in that, In step S2, the mass ratio of aluminum chloride, urea, and chloroplatinic acid is (4.5-5):(0.1-0.25):

1.

8. The method for efficiently synthesizing 3-chlorophenylacetone according to claim 5, characterized in that, In step S2, the mass ratio of aluminum chloride to precursor is (0.015-0.03):1.

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