Method for synthesizing dichloroacetyl compound

Abstract

The invention discloses a method for synthesizing a dichloroacetyl compound, which comprises the following steps: tetrachloroethylene and an acid are subjected to an addition reaction at 100-200 DEG C to obtain an adduct, then the adduct is subjected to an acidolysis, hydrolysis or alcoholysis reaction to obtain the dichloroacetyl compound, the acid for the addition reaction is at least one of sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid and phosphoric acid, and the acid for the alcoholysis reaction is at least one of sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid and phosphoric acid. The molar ratio of the tetrachloroethylene to the acid is 1: (1-10). By controlling the types of acids and increasing the temperature of the addition reaction, the addition reaction of tetrachloroethylene and acids in the absence of a catalyst is realized. Double bonds of tetrachloroethylene and hydrogen protons are subjected to an addition reaction in a strong acid environment to form a cationic intermediate, then the cationic intermediate is combined with acid radical anions to form an adduct, and the adduct intermediate is high in activity, unstable and free of separation and can be directly subjected to a hydrolysis reaction, an acidolysis reaction or an alcoholysis reaction with another substrate (such as water, acid or alcohol) respectively. The synthesis of dichloroacetyl series compounds is realized, and the route has universality and diversity.

Description

Technical Field

[0001] This invention relates to the field of chemical product manufacturing technology, specifically to a method for synthesizing dichloroacetyl compounds. Background Technology

[0002] Tetrachloroethylene is a bulk chemical, with an annual domestic production of approximately 400,000 tons in 2024. It is mainly used as a refrigerant, extractant, and cleaning agent, with few reports of its further conversion into high-value-added chemical products. Dichloroacetyl compounds are an important class of chemical raw materials, commonly used as intermediates in chemical, pharmaceutical, and pesticide processes, and are widely applied in the synthesis of fine chemicals. Their application prospects are very broad, but their traditional synthesis methods are relatively limited.

[0003] Dichloroacetyl chloride is an important intermediate in organic synthesis and pharmaceutical chemistry, primarily used in the synthesis and modification of organopesticide molecules and bioactive molecules. In addition, this substance can also be used for bleaching, decolorization, sterilization, and disinfection. Currently, the main methods for synthesizing dichloroacetyl chloride include: (1) Dichloroacetic acid chlorination method. This method is the earliest industrial route. The raw material is dichloroacetic acid. The chlorination reagents include chlorine, phosphorus pentachloride and thionyl chloride, which usually results in the product containing impurities such as sulfur / phosphorus. (2) Chloroform carbonylation method: the raw materials are chloroform and carbon monoxide. Under the action of aluminum trichloride, carbonylation reaction occurs to generate dichloroacetyl chloride. However, the conversion rate and selectivity are not high. (3) Trichloroethylene oxidation method, which is currently the main production method of dichloroacetyl chloride: under the action of free radical initiators and catalysts, trichloroethylene is oxidized by high-pressure oxygen to produce dichloroacetyl chloride, as shown in the following reaction formula: .

[0004] Chinese patent document CN1131140A discloses a method for preparing dichloroacetyl chloride using azobisisobutyl ester as an initiator and trichloroethylene oxidation. Chinese patent document CN101195563A discloses a process for preparing dichloroacetyl chloride using trichloroethylene as a raw material under metal composite catalyst and air oxidation conditions. However, the trichloroethylene oxidation method has strict requirements on the type and amount of initiator and catalyst. Poor control can produce a large number of byproducts, such as trichloroacetaldehyde and trichloroethylene oxide, as well as phosgene, CO, and CO2. This is considered a hazardous process in industry, and improper control poses significant safety hazards.

[0005] Dichloroacetic acid is also an important chemical intermediate with wide applications in the pharmaceutical and pesticide fields. It can be used to prepare dichloroacetyl chloride, dichloroacetic acid esters, and dichloroacetic acid ammonium, among others. Industrially, dichloroacetic acid is usually a byproduct of the batch process for producing chloroacetic acid, which is not only low-yield and cumbersome but also difficult to purify. Currently, the annual demand for dichloroacetic acid in China is gradually increasing, and existing production capacity cannot meet the corresponding market demand. In addition, as the production process of chloroacetic acid gradually becomes continuous, the purity of the product chloroacetic acid is high, and the content of the byproduct dichloroacetic acid is reduced, further leading to a decrease in the overall supply of dichloroacetic acid.

[0006] The traditional method for synthesizing dichloroacetic acid is as follows: .

[0007] This method uses acetic acid as the starting material and chlorine gas or liquid chlorine as the chlorinating agent to prepare chloroacetic acid by chlorination reaction, while producing dichloroacetic acid as a byproduct. The main catalysts used are sulfur, acetic anhydride, iodine, red phosphorus, phosphorus trichloride, sulfonyl chloride, and acetyl chloride.

[0008] Alternatively, the trichloroacetaldehyde method and the selective dechlorination method of trichloroacetic acid can also be used to prepare dichloroacetic acid, but these processes are complex, the raw materials are not readily available, and the costs are high, making them unsuitable for large-scale production. Reference 1 (Shahnaz Perveen, et al. An Expedient Approach to the Synthesis of Chloroacetic, Dichloroacetic and Acetic Acid Catalyzed by Sulfuric Acid in the Presence of Crown Ethers). Letters in Organic Chemistry (2006, 3, 940-942.) discloses the reaction of dichloroethylene, trichloroethylene, and tetrachloroethylene with water under the catalysis of sulfuric acid and crown ether to produce acetic acid, monochloroacetic acid, and dichloroacetic acid, respectively. However, without crown ether catalysis, the yield of dichloroacetic acid can only reach 51% after 22 h, which is low. In addition, because the crown ether is dehydrated under sulfuric acid conditions, neither the catalyst nor the sulfuric acid can be recovered and reused, which greatly limits its industrial application.

[0009] Dichloroacetic acid ester is also an important chemical intermediate, mainly used in organic synthesis, pharmaceuticals and dyes. Its upstream main raw materials are dichloroacetyl chloride and dichloroacetic acid, and its synthesis depends on dichloroacetyl chloride and dichloroacetic acid.

[0010] Currently, there is no preparation method that can simultaneously produce multiple dichloroacetyl compounds with a high reaction yield. Summary of the Invention

[0011] To address the aforementioned technical problems, this invention provides a method for synthesizing dichloroacetyl compounds. By controlling the concentration of sulfuric acid feedstock and increasing the temperature of the addition reaction, the addition reaction of tetrachloroethylene and sulfuric acid is achieved without a catalyst. The reaction product is then subjected to subsequent acidolysis, hydrolysis, or alcohololysis to synthesize a series of dichloroacetyl compounds. This method offers both versatility and diversity.

[0012] A method for synthesizing dichloroacetyl compounds includes the following steps: Tetrachloroethylene and an acid are subjected to an addition reaction at 100-200 °C to obtain an adduct, which is then subjected to acidolysis, hydrolysis or alcohololysis to obtain a dichloroacetyl compound. The acid in the addition reaction is at least one of sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid, and phosphoric acid, and the molar ratio of tetrachloroethylene to the acid in the addition reaction is 1:1-10.

[0013] This invention achieves the catalyst-free addition reaction of tetrachloroethylene with acids by controlling the type of acid and increasing the temperature of the addition reaction. In a strongly acidic environment, the double bond of tetrachloroethylene undergoes an addition reaction with hydrogen protons to form a cationic intermediate, which then combines with an acid anion to form adducts (i.e., tetrachloroethyl sulfate, tetrachloroethyl trifluoromethanesulfonate, tetrachloroethylene methanesulfonate, and tetrachloroethylene phosphate adducts). These intermediates are unstable and do not require separation; they can directly undergo acidolysis, hydrolysis, or alcohololysis with another substrate (such as an acid, water, or alcohol) to synthesize dichloroacetyl series compounds. This route offers both versatility and variety.

[0014] From an industrial application perspective, sulfuric acid is a widely used, inexpensive, and readily available chemical, making it particularly valuable for industrial applications. This invention utilizes sulfuric acid for further optimization of the technical solution. Furthermore, there is a correlation between the sulfuric acid concentration and the reaction temperature in this invention; when the sulfuric acid concentration is low, the reaction temperature can be appropriately increased to accelerate the reaction process and improve the yield.

[0015] Preferably, the acid is sulfuric acid, and the concentration of the sulfuric acid is ≥80%.

[0016] The specific reaction route is as follows: Preferably, when the sulfuric acid concentration is between 90% and 100%, the temperature of the addition reaction is 100~200 °C.

[0017] In this invention, by controlling the sulfuric acid concentration to be above 90% and increasing the temperature of the addition reaction, tetrachloroethylene and sulfuric acid can undergo an addition reaction without the addition of a crown ether catalyst, thereby achieving the preparation of dichloroacetyl compounds and realizing the recycling and reuse of sulfuric acid raw materials, while improving the yield and purity of dichloroacetyl compounds.

[0018] More preferably, when the sulfuric acid concentration is 98%~100%, the addition reaction temperature is not lower than 100°C; when the sulfuric acid concentration is 95%~98%, the addition reaction temperature is not lower than 140°C; and when the sulfuric acid concentration is 90%~95%, the addition reaction temperature is not lower than 160°C.

[0019] In this invention, the higher the concentration of sulfuric acid, the lower the minimum temperature required for the addition reaction, and vice versa; by increasing the concentration of sulfuric acid and the reaction temperature, the reaction efficiency can be greatly improved.

[0020] More preferably, taking into account both reaction efficiency and safety, when the sulfuric acid concentration is 95%~100%, the addition reaction temperature is 160 ℃.

[0021] Preferably, the acidolysis reaction is as follows: the adduct is reacted with an organic acid at 25~180 °C to obtain dichloroacetyl chloride; The structure of the organic acid is as follows: , wherein, the R 1 It can be a benzene ring, a halogen-substituted benzene ring, a C1-C4 alkyl group, or a C1-C4 halogen-substituted alkyl group.

[0022] In this invention, the tetrachloroethyl sulfate obtained from the addition reaction does not need to be separated and can be directly used in the acidolysis reaction. The reaction products after acidolysis are dichloroacetyl chloride and R. 1 Substituted acyl chloride compounds, therefore, the R of organic acids 1 The type of substituent determines the type of reaction products of acid hydrolysis.

[0023] In this invention, if the organic acid is dichloroacetic acid, the reaction product after acid hydrolysis is a single dichloroacetyl chloride, which facilitates the purification and separation of the product.

[0024] Preferably, the hydrolysis reaction is as follows: the adduct is hydrolyzed with water at 0~100 °C to obtain a dichloroacetyl compound; the molar ratio of tetrachloroethylene to water is 1:1~10; the dichloroacetyl compound is dichloroacetyl chloride and / or dichloroacetic acid.

[0025] In this invention, the tetrachloroethyl sulfate obtained from the addition reaction does not need to be separated and can be directly used in the hydrolysis reaction. When the molar ratio of tetrachloroethylene to water is 1:1, the hydrolysis product is dichloroacetyl chloride; when the molar ratio of tetrachloroethylene to water is 1:2 to 10, the hydrolysis product is dichloroacetic acid; and when the molar ratio of tetrachloroethylene to water is between 1:1 and 2 (excluding 1:1 or 1:2), the hydrolysis product is a mixture of dichloroacetyl chloride and dichloroacetic acid. Therefore, if the target product is dichloroacetic acid or dichloroacetyl chloride, the reaction can be carried out in a one-pot process. The hydrolysis product can be controlled to be dichloroacetic acid, dichloroacetyl chloride, or a mixture of the two by controlling the water content of the sulfuric acid feedstock.

[0026] Preferably, the alcoholysis reaction is as follows: the adduct is reacted with an alcohol at 0-100 °C to yield a dichloroacetyl compound; the molar ratio of the alcohol to tetrachloroethylene is 2-5:1, and the structure of the alcohol is as follows: , where R 2 It is a C1 to C4 alkyl group.

[0027] In this invention, the tetrachloroethyl sulfate obtained from the addition reaction does not need to be separated and can be directly used in the alcoholysis reaction. By controlling the molar ratio of tetrachloroethylene and alcohol, the product dichloroacetic acid alkyl ester can be obtained.

[0028] Preferably, the dichloroacetyl compound is at least one of dichloroacetyl chloride, dichloroacetic acid, and alkyl dichloroacetic acid ester.

[0029] In this invention, when the dichloroacetyl compound product is dichloroacetyl chloride, compared with the currently mainstream trichloroethylene oxidation method, no special equipment or catalyst is required. The trichloroethylene oxidation method has high requirements for catalysts and initiators, and improper control can produce different by-products. However, the reaction process of this invention is completely different from the above methods and will not produce similar by-products. At the same time, the trichloroethylene oxidation method is a dangerous process, and improper control poses a significant safety hazard.

[0030] In this invention, when the dichloroacetyl compound product is dichloroacetic acid, the reaction process is completely different from the current industrial acetic acid chlorination method. There are no problems of insufficient or excessive chlorination, and no byproducts such as monochloroacetic acid and trichloroacetic acid are produced.

[0031] In this invention, the dichloroacetyl compound product is an alkyl ester of dichloroacetic acid, which eliminates the need for pre-synthesizing dichloroacetyl chloride or dichloroacetic acid before esterification, making the route simpler and more economical.

[0032] The main byproduct of this invention is hydrogen chloride gas, which can be collected and utilized comprehensively, reducing the environmental harm caused by waste acid and making it more atom-economical and environmentally friendly.

[0033] Preferably, the yield of the dichloroacetyl compound is ≥80%, and the purity is ≥99%.

[0034] Preferably, after the acidolysis, hydrolysis, or alcohololysis reaction, dichloroacetyl compound is obtained by distillation, and the remaining sulfuric acid is recovered and used in the addition reaction with tetrachloroethylene.

[0035] In this invention, sulfuric acid is not consumed and can be recycled, further reducing costs and minimizing environmental impact.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves a catalyst-free addition reaction between tetrachloroethylene and sulfuric acid by controlling the concentration of sulfuric acid feedstock and increasing the temperature of the addition reaction. Under strongly acidic conditions, the double bond of tetrachloroethylene undergoes an addition reaction with hydrogen protons to form a cationic intermediate, which then combines with a hydrogen sulfate anion to form an adduct (tetrachloroethyl sulfate). This highly reactive and unstable intermediate does not require separation and can directly undergo acidolysis, hydrolysis, or alcohololysis with another substrate (such as acid, water, or alcohol) to synthesize a series of dichloroacetyl compounds. The route is both versatile and diverse, and the recovered sulfuric acid can be recycled, significantly reducing economic costs and environmental hazards. Attached Figure Description

[0037] Figure 1 and Figure 2 The images show the 1H NMR spectrum and HPLC chromatogram of dichloroacetyl chloride prepared in Example 1.

[0038] Figure 3 and Figure 4 The images show the 1H NMR spectrum and HPLC chromatogram of dichloroacetic acid prepared in Example 7.

[0039] Figure 5 and Figure 6 The images show the 1H NMR spectrum and HPLC chromatogram of monochloroacetyl chloride prepared in Example 4.

[0040] Figure 7 and Figure 8 The images show the 1H NMR spectrum and HPLC chromatogram of methyl dichloroacetate prepared in Example 10, respectively.

[0041] Figure 9 and Figure 10 The images show the 1H NMR spectrum and HPLC chromatogram of ethyl dichloroacetate prepared in Example 11, respectively. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments: All raw materials used in this invention are commercially available.

[0043] Example 1: Synthesis of dichloroacetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and dichloroacetic acid (0.1 mol, 12.9 g) was slowly added dropwise. After the addition was complete, the temperature was raised to 80 °C and the reaction was stirred for 2 h. Distillation under normal pressure yielded 24.3 g of a colorless, irritating liquid, dichloroacetyl chloride (yield 83.1%). The 1H NMR spectrum of dichloroacetyl chloride is as follows: 1 ¹H NMR (500 MHz, CDCl₃) δ 6.14 (s, 1H). The ¹H NMR and HPLC results are as follows: Figure 1 and 2 As shown.

[0044] Example 2: Synthesis of dichloroacetyl chloride and benzoyl chloride Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and benzoic acid (0.1 mol, 12.2 g) was slowly added dropwise. After the addition was complete, the temperature was raised to 80 °C and the reaction was stirred for 2 h. Distillation under normal pressure yielded 12.0 g of a colorless, irritating liquid, dichloroacetyl chloride (yield 82.1%), which was further distilled under reduced pressure to yield 11.3 g of benzoyl chloride (yield 80.7%).

[0045] Example 3: Synthesis of dichloroacetyl chloride and acetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and acetic acid (0.1 mol, 6.0 g) was slowly added dropwise. After the addition was complete, the temperature was raised to 80 °C and the reaction was stirred for 2 h. Distillation under normal pressure yielded 13.1 g (89.7%) of colorless, irritating liquid dichloroacetyl chloride and 7.2 g (91.7%) of acetyl chloride.

[0046] Example 4: Synthesis of dichloroacetyl chloride and monochloroacetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and monochloroacetic acid (0.1 mol, 9.4 g) was slowly added dropwise. After the addition was complete, the temperature was raised to 80 °C and the reaction was stirred for 2 h. Distillation under normal pressure yielded 12.7 g (86.8%) of colorless, irritating liquid dichloroacetyl chloride and 10.1 g (90.3%) of monochloroacetyl chloride. The 1H NMR spectrum of monochloroacetyl chloride is as follows: 1 ¹H NMR (500 MHz, CDCl₃) δ 4.54 (s, 1H), ¹H NMR and HPLC results are as follows: Figure 5 and 6 As shown.

[0047] Example 5: Synthesis of dichloroacetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and water (0.1 mol, 1.8 g) was slowly added dropwise using a syringe. After the addition was complete, the mixture was stirred at room temperature for 2 h. Distillation under normal pressure yielded 13.2 g of a colorless, irritating liquid, dichloroacetyl chloride (yield 90.2%).

[0048] Example 6: One-pot direct synthesis of dichloroacetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g), sulfuric acid (100%, 0.2 mol, 19.6 g), and water (0.1 mol, 1.8 g) were added to a reaction flask. Nitrogen gas was purged three times, and the flask was placed in an oil bath at 160 °C and heated with stirring for 10 h. After the reaction was completed, the reaction flask was cooled to room temperature and distilled under normal pressure to obtain 12.2 g of a colorless, irritating liquid, dichloroacetyl chloride (yield 83.6%).

[0049] Example 7: Synthesis of dichloroacetic acid Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and water (0.2 mol, 3.6 g) was slowly added dropwise using a syringe. After the addition was complete, the mixture was stirred at room temperature for 2 h. Distillation under normal pressure yielded 12.1 g of colorless liquid dichloroacetic acid (94.6% yield). The 1H NMR spectrum of dichloroacetic acid is as follows: 1¹H NMR (500MHz, CDCl₃) δ 11.27 (s, 1H), 6.02 (s, 1H). The ¹H NMR and HPLC results are as follows: Figure 3 and 4 As shown.

[0050] Example 7: One-pot direct synthesis of dichloroacetic acid Tetrachloroethylene (0.1 mol, 16.6 g), sulfuric acid (100%, 0.2 mol, 19.6 g), and water (0.2 mol, 3.6 g) were added to a reaction flask. Nitrogen gas was purged three times, and the flask was placed in an oil bath at 160 °C and heated with stirring for 10 h. After the reaction was completed, the reaction flask was cooled to room temperature and distilled under normal pressure to obtain 11.8 g of colorless liquid dichloroacetic acid (yield 92.3%).

[0051] Example 8: One-pot direct synthesis of dichloroacetic acid, with the sulfuric acid recovered for reuse. Tetrachloroethylene (0.1 mol, 16.6 g), sulfuric acid (100%, 0.2 mol, 19.6 g), and water (0.2 mol, 3.6 g) were added to a reaction flask. Nitrogen gas was purged three times, and the flask was placed in an oil bath at 160 °C and heated with stirring for 10 h. After the reaction was complete, the flask was cooled to room temperature and distilled under normal pressure to obtain 11.8 g of colorless liquid dichloroacetic acid (yield 92.3%). The residual sulfuric acid in the flask was directly used to react with the next batch of tetrachloroethylene, and the results are shown below.

[0052] Table 1: Batch and Yield of Recycled Sulfuric Acid for Continued Use Example 9: Synthesis of methyl dichloroacetate Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and methanol (0.3 mol, 9.6 g) was slowly added dropwise using a syringe. After the addition was complete, the mixture was stirred at room temperature for 2 h. Distillation under normal pressure yielded 12.5 g of colorless liquid methyl dichloroacetate (yield 87.8%). The 1H NMR spectrum of methyl dichloroacetate is as follows: 1 ¹H NMR (500 MHz, CDCl₃) δ 6.01 (s, 1H), 3.91 (s, 3H), ¹H NMR and HPLC are as follows: Figure 7 and 8 As shown.

[0053] Example 10: Synthesis of Ethyl Dichloroacetate Tetrachloroethylene (0.1 mol, 16.6 g) and sulfuric acid (100%, 0.2 mol, 19.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature, and ethanol (0.3 mol, 13.8 g) was slowly added dropwise using a syringe. After the addition was complete, the mixture was stirred at room temperature for 2 h. Distillation under normal pressure yielded 13.3 g of colorless liquid ethyl dichloroacetate (yield 85.3%). The 1H NMR spectrum of ethyl dichloroacetate is as follows: 1 HNMR (500 MHz, CDCl3) δ 5.98 (s, 1H), 4.34 (q, J = 7.2 Hz, 2H), 1.36 (t, J =7.2 Hz, 1H), 1H spectrum and HPLC are as follows Figure 9 and 10 As shown.

[0054] Example 11: Synthesis of dichloroacetyl chloride Tetrachloroethylene (0.1 mol, 16.6 g), trifluoromethanesulfonic acid (0.2 mol, 30.0 g), and water (0.1 mol, 1.8 g) were added to a reaction flask to purge nitrogen three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature and distilled under normal pressure to obtain 10.6 g of a colorless, irritating liquid, dichloroacetyl chloride (yield 72.4%).

[0055] Example 12: Synthesis of dichloroacetic acid Tetrachloroethylene (0.1 mol, 16.6 g), trifluoromethanesulfonic acid (0.2 mol, 30.0 g), and water (0.2 mol, 3.6 g) were added to a reaction flask to purge nitrogen three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature and distilled under reduced pressure to obtain 10.1 g of colorless liquid dichloroacetic acid (yield 78.8%).

[0056] Example 13: Synthesis of dichloroacetic acid Tetrachloroethylene (0.1 mol, 16.6 g), methanesulfonic acid (0.2 mol, 19.2 g), and water (0.2 mol, 3.6 g) were added to a reaction flask, and nitrogen gas was purged three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the reaction flask was cooled to room temperature and distilled under reduced pressure to obtain 6.2 g of colorless liquid dichloroacetic acid (yield 48.2%).

[0057] Example 13: Synthesis of dichloroacetic acid Tetrachloroethylene (0.1 mol, 16.6 g), 85% phosphoric acid (0.2 mol, 23.0 g), and water (0.2 mol, 3.6 g) were added to a reaction flask to purge nitrogen three times. The flask was then placed in an oil bath at 160 °C and heated with stirring for 8 h. After the reaction was complete, the flask was cooled to room temperature and distilled under reduced pressure to obtain 3.1 g of colorless liquid dichloroacetic acid (yield 23.6%).

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, such as common technical optimization methods like reaction temperature, reactant concentration, reaction time, and reactant equivalence ratio, should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing a dichloroacetyl compound, characterized in that, Includes the following steps: Tetrachloroethylene and an acid are subjected to an addition reaction at 100-200 °C to obtain an adduct, which is then subjected to acidolysis, hydrolysis or alcohololysis to obtain a dichloroacetyl compound. The acid in the addition reaction is at least one of sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid, and phosphoric acid, and the molar ratio of tetrachloroethylene to the acid in the addition reaction is 1:1-10.

2. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The acid used in the addition reaction is sulfuric acid, and the concentration of the sulfuric acid is ≥80%.

3. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The dichloroacetyl compound is at least one of dichloroacetyl chloride, dichloroacetic acid, and alkyl dichloroacetic acid esters.

4. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The acidolysis reaction is as follows: the adduct is reacted with an organic acid at 25~180 °C to produce dichloroacetyl chloride; The structure of the organic acid is as follows: , wherein, the R 1 It can be a benzene ring, a halogen-substituted benzene ring, a C1-C4 alkyl group, or a C1-C4 halogen-substituted alkyl group.

5. The method for synthesizing a dichloroacetyl compound according to claim 4, characterized in that, When the organic acid is dichloroacetic acid, the product of the acidolysis reaction is a single dichloroacetyl chloride.

6. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The hydrolysis reaction is as follows: the adduct is hydrolyzed with water at 0~100 °C to obtain a dichloroacetyl compound; The molar ratio of tetrachloroethylene to water is 1:1 to 10; the dichloroacetyl compound is dichloroacetyl chloride and / or dichloroacetic acid.

7. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The alcoholysis reaction is as follows: the adduct is reacted with an alcohol at 0~100 °C to produce an alkyl dichloroacetic acid ester; The molar ratio of the alcohol to tetrachloroethylene is 2-5:1, and the structure of the alcohol is as follows: , where R 2 It is a C1 to C4 alkyl group.

8. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, The yield of the dichloroacetyl compound is ≥80%, and the purity is ≥99%.

9. The method for synthesizing a dichloroacetyl compound according to claim 1, characterized in that, After the acidolysis, hydrolysis, or alcohololysis reaction, dichloroacetyl compound is obtained by distillation, and the remaining sulfuric acid is recovered and reused in the addition reaction with tetrachloroethylene.

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