Method for efficiently synthesizing 3-chloropropiophenone

Abstract

The invention relates to the technical field of organic synthesis, and particularly discloses a method for efficiently synthesizing 3-chloropropiophenone. The invention relates to a method for efficiently synthesizing 3-chloropropiophenone, which comprises the following steps: 1) carrying out alkaline hydrolysis reaction on m-chlorobenzonitrile, and then carrying out acidification reaction to obtain m-chlorobenzoic acid; and 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 heating to carry out a decarboxylation reaction, then heating to remove the residual propionic acid, when a distillate begins to appear, absorbing the distillate with a solvent to obtain an absorption liquid, and then cooling and crystallizing the absorption liquid to obtain the 3-chloropropiophenone. The synthesis method has the advantages of high efficiency and low cost.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and more specifically, to a method for efficiently synthesizing 3-chloropropiophenone. Background Art

[0002] 3-Chloropropiophenone is an important pharmaceutical intermediate, occurring as white or yellow crystals. As a phenylpropiophenone derivative, 3-chloropropiophenone possesses similar physical and chemical properties to phenylpropiophenone and can undergo a variety of chemical transformations. It is widely used in organic synthetic chemistry, particularly in the synthesis of psychotropic drugs.

[0003] The most established synthesis method for 3-chloropropiophenone utilizes acylation and chlorination reactions. First, the intermediate propiophenone is produced through acylation, which is then chlorinated to produce 3-chloropropiophenone. The raw materials for the acylation reaction are generally benzene and propionyl chloride, and 1,2-dichloroethane is required as the solvent and aluminum chloride as the catalyst. However, 1,2-dichloroethane is flammable and highly toxic, while aluminum chloride readily absorbs water and hydrolyzes during the reaction. Furthermore, the acylation reaction produces large amounts of hydrogen chloride gas and acidic wastewater.

[0004] Chinese patent application publication number CN117886683A discloses a method for preparing m-chloropropiophenone. The method involves introducing nitrogen into an acylation kettle to displace the air in the kettle, thereby reducing the humidity of the gas in the kettle until the humidity is below 5%, and then closing valves 1 and 2. This method prevents the acylation reaction raw materials from being exposed to air and prevents flocculent precipitation caused by the hydrolysis of aluminum trichloride. However, the method does not fundamentally address the shortcomings of the acylation and chlorination reaction routes.

[0005] Another example of a method for synthesizing 3-chloropropiophenone is disclosed in the prior art. Using m-chlorobenzonitrile as a raw material, magnesium metal reacts in tetrahydrofuran to produce a Grignard reagent, which is then subjected to a nucleophilic addition reaction between ethylmagnesium bromide and m-chlorobenzonitrile. Hydrochloric acid is then added dropwise for a hydrolysis reaction to produce 3-chloropropiophenone. This method does not require an acylation reaction or a chlorination reaction, but the Grignard reagent required for the reaction is difficult to prepare, has low production efficiency, and is expensive, making it unsuitable for industrial production. Therefore, exploring and finding a more efficient and low-cost 3-chloropropiophenone remains an urgent problem to be solved. Summary of the Invention

[0006] In order to further improve the synthesis efficiency of 3-chloropropiophenone, the present application provides a method for efficiently synthesizing 3-chloropropiophenone.

[0007] The present application provides a method for efficiently synthesizing 3-chloropropiophenone, which adopts the following technical solution: A method for efficiently synthesizing 3-chloropropiophenone comprises the following steps: 1) subjecting m-chlorobenzonitrile to an alkaline hydrolysis reaction and then to an acidification reaction to prepare m-chlorobenzoic acid; 2) The m-chlorobenzoic acid obtained in step 1) is first subjected to a condensation reaction with propionic acid in the presence of a catalyst, and then the temperature is raised to perform a decarboxylation reaction. The remaining propionic acid is then removed by raising the temperature. When distillate begins to appear, the distillate is absorbed by a solvent to obtain an absorption liquid, and the absorption liquid is then cooled and crystallized to obtain 3-chloropropiophenone.

[0008] Preferably, the step 1) further includes at least one of the following technical features: 11) The base 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°C; 13) The temperature of the acidification reaction is 20-35°C; 14) The acid used in the acidification reaction is hydrochloric acid or sulfuric acid; 15) During the alkaline hydrolysis reaction, quaternary ammonium base and dimethyl sulfoxide are also added.

[0009] Preferably, the quaternary ammonium base is one or more of tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide.

[0010] Preferably, the molar ratio of the quaternary ammonium base to dimethyl sulfoxide is (0.08-0.2):1.

[0011] Preferably, the 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°C; 23) The condensation reaction time is 6-8 hours; 24) The decarboxylation reaction time is 1-2 hours; 25) The decarboxylation reaction temperature is 200-280°C; 26) The catalyst includes a first catalyst and a second catalyst, wherein the first catalyst includes iron powder and cobalt oxide; 27) The mass ratio of m-chlorobenzoic acid to catalyst is 1:(0.2-25); 28) The solvent is ethanol or ethyl acetate.

[0012] Preferably, the first catalyst is composed of iron powder and cobalt oxide in a mass ratio of 1:(0.2-0.3).

[0013] Preferably, the second catalyst is prepared by the following steps: S1: Hexadecyltrimethylammonium bromide, carrageenan, and deionized water are mixed uniformly to prepare a base liquid, and then sodium silicate solution is added to the base liquid. The mixture is aged at 120-135° C., filtered and washed to obtain a solid, and the solid is calcined to obtain a precursor material. S2: Dissolve aluminum chloride, urea, and chloroplatinic acid in anhydrous ethanol, then add the precursor and stir evenly. Then increase the temperature and continue stirring. After the ethanol is evaporated, calcine the resulting powder.

[0014] Preferably, in step S1, the mass ratio of cetyltrimethylammonium bromide, carrageenan and deionized water is (0.17-0.19):(0.05-0.1):1.

[0015] Preferably, in step S2, the mass ratio of aluminum chloride, urea and chloroplatinic acid is (4.5-5):(0.1-0.25):1.

[0016] Preferably, in step S2, the mass ratio of aluminum chloride to precursor is (0.015-0.03):1.

[0017] In summary, this application has the following beneficial effects: 1. This application uses m-chlorobenzonitrile as a raw material, which is first subjected to alkaline hydrolysis and acidification, followed by a condensation reaction with propionic acid and a decarboxylation reaction. The synthesis process does not require acylation or chlorination reactions, and does not produce toxic and harmful gases or acidic wastewater. Furthermore, the auxiliary chemicals used in this synthesis process are inexpensive and readily available, resulting in low production costs and suitability for industrial production.

[0018] 2nd, the application adds the first catalyst and the second catalyst during condensation reaction, wherein, the iron powder and cobalt oxide in the first catalyst can reduce reaction activation energy, and reaction temperature is decreased, and condensation reaction efficiency and product yield can be greatly improved. In addition, the second catalyst of the application adopts hexadecyltrimethylammonium bromide, carrageenan as composite component configuration base liquid, adds ageing, calcination after sodium silicate, gained precursor material has larger specific surface area, and then with aluminum chloride, urea, chloroplatinic acid compound, aluminum element and platinum element are loaded in the pore structure of precursor material, activate the relevant covalent bonds such as C-O key in the reaction process, promote proton to transfer, and promote the efficiency of decarboxylation reaction. In addition, after adding urea, the pore structure orderliness of precursor material can be improved, and nitrogen vacancy is introduced, contact area and mass transfer efficiency and active site quantity are increased between reactant and the second catalyst, so as to improve overall synthesis efficiency.

[0019] 3. The present application adopts a compound of the first catalyst and the second catalyst. In the condensation reaction stage, the first catalyst is dominant, and in the decarboxylation stage, as the reaction temperature continues to increase, 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, thereby promoting the adsorption and reaction of the reactants in the pore structure of the second precursor, thereby obtaining a higher yield and selectivity, while also reducing the reaction temperature, and the entire reaction process is carried out more efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a TEM image of the second catalyst of Example 2 of the present application.

[0021] Figure 2 This is a TEM image of the second catalyst in Example 3 of the present application.

[0022] Figure 3 It is a schematic diagram of the catalytic activity stability data of the second catalyst in Examples 2 and 3 of the present application. DETAILED DESCRIPTION

[0023] The present application is further described in detail below with reference to the embodiments.

[0024] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0025] After extensive experimental research, the inventors of this application have provided a new and efficient method for synthesizing 3-chloropropiophenone, which has the advantages of high yield, low cost, simple route, efficient reaction, and economy and environmental protection.

[0026] The method for efficiently synthesizing 3-chloropropiophenone of the present application comprises the following steps: 1) subjecting m-chlorobenzonitrile to an alkaline hydrolysis reaction and then to an acidification reaction to prepare m-chlorobenzoic acid; 2) The m-chlorobenzoic acid obtained in step 1) is first subjected to a condensation reaction with propionic acid in the presence of a catalyst, and then the temperature is raised to perform a decarboxylation reaction. The remaining propionic acid is then removed by raising the temperature. When distillate begins to appear, the distillate is absorbed by a solvent to obtain an absorption liquid, and the absorption liquid is then cooled and crystallized to obtain 3-chloropropiophenone.

[0027] Preferably, step 1) further includes at least one of the following technical features: 11) The base 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°C; 13) The temperature of the acidification reaction is 20-35°C; 14) The acid used in the acidification reaction is hydrochloric acid or sulfuric acid; 15) During the alkaline hydrolysis reaction, quaternary ammonium base and dimethyl sulfoxide are also added.

[0028] In some specific embodiments, in step 1), the base 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 for alkaline hydrolysis. The temperature of the alkaline hydrolysis reaction is 75-90°C, for example, 75-80°C, 80-85°C, or 85-90°C. Generally, a temperature of 85°C is preferred for better results. The temperature of the acidification reaction is 20-35°C, for example, 20°C, 25°C, 30°C, or 35°C. The quaternary ammonium base is one or more of tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide. Generally, tetrabutylphosphonium hydroxide is preferred for 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, (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, 0.2:1, etc. Under normal circumstances, better effects can be obtained when the molar ratio of the quaternary ammonium base to dimethyl sulfoxide is 0.15:1.

[0029] Preferably, the 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°C; 23) The condensation reaction time is 6-8 hours; 24) The decarboxylation reaction time is 1-2 hours; 25) The decarboxylation reaction temperature is 200-280°C; 26) The catalyst includes a first catalyst and a second catalyst, wherein the first catalyst includes iron powder and cobalt oxide; 27) The mass ratio of m-chlorobenzoic acid to catalyst is 1:(0.2-25); 28) The solvent is ethanol or ethyl acetate.

[0030] 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, (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. Under normal circumstances, the molar ratio of m-chlorobenzoic acid to propionic acid is 0.16:1, which has a better effect.

[0031] In some specific embodiments, the condensation reaction temperature can be 120-125°C, 125-130°C, 130-135°C, more preferably, for example, 120°C, 125°C, 128°C, 130°C, 132°C, 135°C.

[0032] 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.

[0033] Preferably, the second catalyst is prepared by the following steps: S1: Hexadecyltrimethylammonium bromide, carrageenan, and deionized water are mixed uniformly to prepare a base liquid, and then sodium silicate solution is added to the base liquid. The mixture is aged at 120-135° C., filtered and washed to obtain a solid, and the solid is calcined to obtain a precursor material. S2: Dissolve aluminum chloride, urea, and chloroplatinic acid in anhydrous ethanol, then add the precursor and stir evenly. Then increase the temperature and continue stirring. After the ethanol is evaporated, calcine the resulting powder.

[0034] In some specific embodiments, in step S1, the mass ratio of cetyltrimethylammonium 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, more preferably, it can be 0.17:0.05:1, 0.17:0.07:1, 0.17:0.08:1, 0.17:0.09:1, 0.18:0.05:1 , 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, 0.19:0.1:1, under normal circumstances, the effect is better when the mass ratio of hexadecyltrimethylammonium bromide, carrageenan and deionized water is 0.19:0.07:1.

[0035] 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):(0.1-0.2 ):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. Usually, the effect is better when the mass ratio of aluminum chloride, urea and chloroplatinic acid is 4.6:0.2:1.

[0036] 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, (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, 0.03:1. Under normal circumstances, the effect is better when the mass ratio of aluminum chloride to the precursor is 0.02:1.

[0037] In some specific embodiments, in step S1, the molar ratio of sodium silicate to hexadecyltrimethylammonium bromide is (20-25):1. Generally, when the molar ratio of sodium silicate to hexadecyltrimethylammonium bromide is 22:1, the effect is better. Example

[0038] The method for efficiently synthesizing 3-chloropropiophenone of the present embodiment comprises the following steps: 1) To a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, 0.2 mol of m-chlorobenzonitrile was added, followed by 0.75 mol of sodium hydroxide and 200 g of glycerol. The temperature was raised to 85°C for alkaline hydrolysis for 5 h, followed by cooling to 25°C. 30% hydrochloric acid was added for acidification, filtered, and washed with deionized water to obtain a white solid. After drying, m-chlorobenzoic acid was obtained with a yield of 95.8% and a purity of 99.1%. 2) Into a four-necked flask equipped with an electric stirrer, a thermometer, and a condenser, 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 7.2 g of a catalyst were added. The mixture was stirred evenly and heated to 135°C for a condensation reaction. After reacting for 7 hours, the excess propionic acid was fractionated and then heated to 280°C for a decarboxylation reaction. When gaseous and liquid distillates began to appear, the distillates were absorbed with ethanol to obtain an absorption liquid. The reaction was stopped after 1.5 hours when no distillate was produced. The absorption liquid was then distilled to remove ethanol. After cooling and crystallization, a white solid product was obtained. The white solid product was recrystallized from ethanol to obtain 3-chloropropiophenone in a yield of 71.5% and a purity of 99.3%.

[0039] The catalyst consists of 6g iron powder and 1.2g cobalt oxide, and the average particle size of the iron powder is 500nm. Example

[0040] The method for efficiently synthesizing 3-chloropropiophenone of the present embodiment comprises the following steps: 1) To a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, 0.2 mol of m-chlorobenzonitrile was added, followed by 0.75 mol of sodium hydroxide and 200 g of glycerol. The temperature was raised to 85°C for alkaline hydrolysis for 5 h, followed by cooling to 25°C. 30% hydrochloric acid was added for acidification, filtered, and washed with deionized water to obtain a white solid. After drying, m-chlorobenzoic acid was obtained with a yield of 95.5% and a purity of 98.9%. 2) Into a four-necked flask equipped with an electric stirrer, a thermometer, and a condenser, 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 9 g of a catalyst were added. The mixture was stirred evenly and heated to 135°C for a condensation reaction. After 7 hours of reaction, the excess propionic acid was fractionated and then the temperature was raised to 255°C for a decarboxylation reaction. When gaseous and liquid distillates began to appear, the distillates were absorbed with ethanol to obtain an absorption liquid. The reaction was stopped after 1.5 hours when no distillate was produced. The absorption liquid was then distilled to remove ethanol. After cooling and crystallization, a white solid product was obtained. The white solid product was recrystallized from ethanol to obtain 3-chloropropiophenone in a yield of 75.2% and a purity of 99.5%.

[0041] The catalyst consists of 7.2 g of a first catalyst and 1.8 g of a second catalyst. The first catalyst consists of 6 g of iron powder and 1.2 g of cobalt oxide. The average particle size of the iron powder is 500 nm.

[0042] The second catalyst of this embodiment is prepared by the following steps: S1: 7.6 g of hexadecyltrimethylammonium bromide and 40 g of deionized water were weighed and mixed to obtain a base liquid. Then, a sodium silicate solution was slowly added to the base liquid. The sodium silicate solution was prepared by dissolving 55.8 g of sodium silicate ninehydrate in 80 g of deionized water. After the sodium silicate solution was added dropwise, the pH value was adjusted to 11. The mixture was then heated to 125° C. and aged for 24 h. After filtering, the mixture was washed with deionized water until neutral to obtain a solid. The solid was placed in a muffle furnace and heated to 600° C. at a heating rate of 1.5° C. / min. The precursor was calcined in an air atmosphere for 5 h to obtain a precursor. S2: Dissolve aluminum chloride in anhydrous ethanol, then add the precursor and stir evenly, control the mass ratio of aluminum chloride to precursor to 0.02:1, then heat to 60°C for hydrothermal reaction, and after the ethanol is evaporated, transfer the resulting powder to a muffle furnace and heat it to 550°C at a heating rate of 2°C / min, and calcine in air atmosphere for 6 hours. Example

[0043] The method for efficiently synthesizing 3-chloropropiophenone of the present embodiment comprises the following steps: 1) To a three-necked flask equipped with a stirrer, thermometer, and dropping funnel, 0.2 mol of m-chlorobenzonitrile was added, followed by 0.75 mol of sodium hydroxide and 200 g of glycerol. The temperature was raised to 85°C for alkaline hydrolysis for 5 h, followed by cooling to 25°C. 30% hydrochloric acid was added for acidification, filtered, and washed with deionized water to obtain a white solid. After drying, m-chlorobenzoic acid was obtained with a yield of 95.6% and a purity of 99%. 2) Into a four-necked flask equipped with an electric stirrer, a thermometer, and a condenser, 0.24 mol of m-chlorobenzoic acid obtained in step 1), 1.5 mol of propionic acid, and 9 g of a catalyst were added. The mixture was stirred evenly and heated to 135°C for a condensation reaction. After 7 hours of reaction, the excess propionic acid was fractionated and then the temperature was raised to 220°C for a decarboxylation reaction. When gaseous and liquid distillates began to appear, the distillates were absorbed with ethanol to obtain an absorption liquid. After 1.5 hours, when no distillate was produced, the reaction was stopped. The absorption liquid was then distilled to remove ethanol. After cooling and crystallization, a white solid product was obtained. The white solid product was recrystallized from ethanol to obtain 3-chloropropiophenone in a yield of 88.7% and a purity of 99.6%.

[0044] The catalyst consists of 7.2 g of a first catalyst and 1.8 g of a second catalyst. The first catalyst consists of 6 g of iron powder and 1.2 g of cobalt oxide. The average particle size of the iron powder is 500 nm.

[0045] The second catalyst of this embodiment is prepared by the following steps: S1: 7.6 g of hexadecyltrimethylammonium bromide, 2.8 g of carrageenan, and 40 g of deionized water were weighed and mixed to obtain a base liquid. Then, a sodium silicate solution was slowly added to the base liquid. The sodium silicate solution was prepared by dissolving 55.8 g of sodium silicate nonahydrate in 80 g of deionized water. After the sodium silicate solution was added dropwise, the pH value was adjusted to 11. The mixture was then heated to 125° C. and aged for 24 h. After filtering, the mixture was washed with deionized water until neutral to obtain a solid. The solid was placed in a muffle furnace and heated to 600° C. at a heating rate of 1.5° C. / min. The precursor was calcined in an air atmosphere for 5 h to obtain a precursor. 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°C for hydrothermal reaction. After the ethanol is evaporated, transfer the resulting powder to a muffle furnace and heat it to 550°C at a heating rate of 2°C / min. Calcinate in air atmosphere for 6 hours.

[0046] Performance testing 1. The second catalysts of Example 2 and Example 3 were tested by transmission electron microscopy. The test results are as follows: Figure 1 and Figure 2As shown, it can be seen that the second catalyst prepared in Example 3 has a better pore structure morphology, a larger specific surface area and catalytic activity, while the second catalyst in Example 2 has a larger proportion of agglomeration phenomenon, a pore structure morphology worse than that in Example 3, and a lower mass transfer efficiency.

[0047] 2. The catalysts of Examples 2 and 3 were subjected to repeated experiments according to the experimental methods of Examples 2 and 3. After each experiment, the catalysts were recovered and rinsed with hot methanol solution to test the catalytic activity stability of the catalysts. The results are shown in FIG. Figure 3 As shown, the horizontal axis is the number of experiments (s), and the vertical axis is the yield of 3-chloropropiophenone (%). Figure 3 It can be seen that although the activity of Example 3 has decreased, the reason for the decrease may be that the catalyst has a certain mass loss during recovery, and the catalytic activity of the catalyst remains stable as a whole.

[0048] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for efficiently synthesizing 3-chloropropiophenone, characterized in that: The method comprises the following steps: 1) subjecting m-chlorobenzonitrile to an alkaline hydrolysis reaction and then to an acidification reaction to prepare m-chlorobenzoic acid; 2) subjecting the m-chlorobenzoic acid obtained in step 1) to a condensation reaction with propionic acid under the action of a catalyst, then heating the m-chlorobenzoic acid to a decarboxylation reaction, and then heating the remaining propionic acid to remove the remaining propionic acid, and when distillate begins to appear, absorbing the distillate with a solvent to obtain an absorption liquid, and then cooling and crystallizing the absorption liquid to obtain 3-chloropropiophenone.

2. A method for efficiently synthesizing 3-chloropropiophenone according to claim 1, characterized in that, The step 1) also includes at least one of the following technical features: 11) the base 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°C; 13) the temperature of the acidification reaction is 20-35°C; 14) the acid used in the acidification reaction is hydrochloric acid or sulfuric acid; 15) quaternary ammonium base and dimethyl sulfoxide are also added in the alkaline hydrolysis reaction.

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

4. A method for efficiently synthesizing 3-chloropropiophenone 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. A method for efficiently synthesizing 3-chloropropiophenone according to claim 1, characterized in that: The step 2) also 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°C; 23) the condensation reaction time is 6-8h; 24) the decarboxylation reaction time is 1-2h; 25) the decarboxylation reaction temperature is 200-280°C; 26) the catalyst includes a first catalyst and a second catalyst, the first catalyst includes iron powder and cobalt oxide; 27) the mass ratio of m-chlorobenzoic acid to catalyst is 1:(0.2-25); 28) the solvent is ethanol or ethyl acetate.

6. A method for efficiently synthesizing 3-chloropropiophenone according to claim 5, characterized in that: The first catalyst is composed of iron powder and cobalt oxide in a mass ratio of 1:(0.2-0.3).

7. A method for efficiently synthesizing 3-chloropropiophenone according to claim 5, characterized in that: The second catalyst is prepared by the following steps: S1: cetyltrimethylammonium bromide, carrageenan and deionized water are mixed evenly to prepare a base liquid, and then a sodium silicate solution is added to the base liquid, and an aging reaction is carried out at 120-135° C., and a solid is obtained by filtering and washing, and the solid is roasted to obtain a precursor material; S2: aluminum chloride, urea and chloroplatinic acid are dissolved in anhydrous ethanol, and then the precursor material is added and stirred evenly, and then the temperature is increased and stirred continuously, and the obtained powder is calcined after the ethanol is evaporated to dryness.

8. A method for efficiently synthesizing 3-chloropropiophenone according to claim 7, characterized in that: In the step S1, the mass ratio of hexadecyltrimethylammonium bromide, carrageenan and deionized water is (0.17-0.19):(0.05-0.1):

1.

9. A method for efficiently synthesizing 3-chloropropiophenone according to claim 7, 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.

10. A method for efficiently synthesizing 3-chloropropiophenone according to claim 7, characterized in that: In step S2, the mass ratio of aluminum chloride to precursor is (0.015-0.03):1.

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