Synthetic method of acryloyl chloride

Abstract

The invention discloses a synthetic method of acryloyl chloride, which comprises the following steps: continuously introducing phosgene into an extraction agent, keeping the temperature at-20 DEG C to 40 DEG C, and dropwise adding a mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor for reaction to complete the synthesis of the acryloyl chloride. According to the method for synthesizing the acryloyl chloride, the acrylic acid is used as a raw material, the phosgene is used as an acylating chlorination reagent, the cosolvent, the extraction agent and the polymerization inhibitor are introduced, and the temperature in the reaction process is optimized, so that the sufficient reaction of the phosgene and the acrylic acid can be promoted, and the acryloyl chloride can be effectively prevented from being contacted with HCl; therefore, high-yield and high-purity acryloyl chloride can be rapidly and simply prepared, the product content is larger than or equal to 99.5%, the yield is larger than or equal to 99%, the method has the advantages of being easy and convenient to operate, mild in reaction condition, easy to obtain raw materials, environmentally friendly, high in purity, high in yield and the like, the product competitiveness can be improved, industrial application can be conveniently achieved, and the industrial practicability is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and relates to a synthesis method of acryloyl chloride, in particular to a method for preparing acryloyl chloride by taking phosgene as an acyl chloride reagent and taking acrylic acid as a raw material. BACKGROUND

[0002] Acryloyl chloride is a high-activity α, β-unsaturated acyl chloride compound, and contains a double bond and an acyl chloride functional group in the molecular structure. Acryloyl chloride has become a key intermediate in the fields of medicine, pesticides, material science and electronic new energy, and has a wide application prospect. For example, in the field of medicine, it is used for synthesizing antibiotic side chain modification and targeted drug carriers; in the field of pesticides, it is used as an important precursor of new fungicides and seed treatment agents; and in the field of material science, it is widely used in the preparation of high-performance resins, photocuring coatings and semiconductor packaging materials. The structural formula of acryloyl chloride is as follows: .

[0003] At present, typical cases of the synthesis method of acryloyl chloride reported at home and abroad are as follows: Method one: the dichloro sulfoxide is fed from the bottom of the rectifying tower, the acrylic acid and the polymerization inhibitor are mixed and then fed from the middle of the rectifying tower, and the generated acryloyl chloride is continuously distilled out during the reaction to realize continuous feeding and discharging. However, this method has the defects of complex operation, complex steps, difficult treatment of three wastes and the like.

[0004] Method two: acryloyl chloride is prepared by eliminating the HCl molecules of β-chloropropionyl chloride. The yield of acryloyl chloride produced by this method is low (≤80%), the raw material cost is high, the profit is low, and this method is not suitable for industrial production.

[0005] Method three: acryloyl chloride is synthesized by taking phosphorus oxychloride as an acyl chloride reagent, and the reaction process and the distillation process are synchronized to realize continuous feeding and discharging. This method has a large operation difficulty in controlling the feeding speed to be consistent with the distillation speed; the by-product phosphorous acid will produce a large amount of phosphorus-containing three wastes, and in recent years, the policy has built an environmental supervision system covering the whole chain of phosphorus-containing three wastes. The limitation of the enterprises discharging phosphorus-containing three wastes in production is increasingly strict, and therefore the industrial production is difficult.

[0006] Method four: phosgene is used as an acyl chloride reagent to synthesize acryloyl chloride by adopting a conventional one-pot method, instead of dichloro sulfoxide and phosphorus oxychloride. Although this method can reduce the three wastes, it also has the following defects: acryloyl chloride is prone to anti-Markovnikov addition with the by-product HCl to generate 3-chloropropionyl chloride, resulting in low content and yield of acryloyl chloride, wherein the content is only 97% and the yield is only 69.3%, and the industrial application prospect is poor.

[0007] Method five: the following defects exist in the synthesis of acryloyl chloride with triphosgene as an acyl chloride reagent: triphosgene used is solid phosgene, which needs to be depolymerized at high temperature to generate gaseous phosgene to react, the effective collision probability of the generated gaseous phosgene after depolymerization with raw materials is low, resulting in large consumption of triphosgene and long reaction time; in addition, the depolymerization at high temperature consumes organic nitrogen compounds in the system, which not only reduces the reaction efficiency, but also promotes the occurrence of side reactions, making the product and raw materials more prone to self-polymerization, and it is difficult to obtain acryloyl chloride with a content of less than 99.5% and a yield of less than 98%; It can be seen that in the existing synthesis methods of acryloyl chloride, on the one hand, no matter which acyl chloride reagent is used, the traditional one-pot synthesis will cause the addition reaction (mainly anti-Markovnikov addition) of the product acryloyl chloride and by-product HCl or the self-polymerization reaction under the catalysis of strong acid, which increases the difficulty of subsequent separation, reduces the product content and yield; on the other hand, some new technical routes reported at present mainly use the method of separating the generated acryloyl chloride from the system in time while feeding to avoid the occurrence of side reactions, but the separation method is mainly distillation, which uses a large amount of solvent for dilution to reduce the occurrence of side reactions, increases the separation cost, and also increases the difficulty of treatment of three wastes; and the addition and self-polymerization side reactions of acryloyl chloride still occur at the discharge temperature, and since the feeding rate and the production rate need to be controlled to be approximately the same, the operation is complex and the reaction progress is not easy to control.

[0008] When phosgene is used to synthesize acryloyl chloride, the main reaction is as shown in the following formula: .

[0009] Since the acyl chloride group is a strong electron-withdrawing group, the product acryloyl chloride is prone to anti-Markovnikov addition with HCl to generate 3-chloropropionyl chloride, and the reaction formula is as shown in the following formula: .

[0010] Under acidic conditions, the product acryloyl chloride is prone to self-polymerization to generate a polymer of acryloyl chloride, and the reaction formula is as shown in the following formula: .

[0011] Therefore, obtaining a synthesis method of acryloyl chloride which is simple in operation, mild in reaction conditions, easy to obtain raw materials, green and environmentally friendly, high in purity and high in yield has a promoting effect on improving the competitiveness of acryloyl chloride and promoting the wide use of acryloyl chloride. SUMMARY

[0012] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a synthesis method of acryloyl chloride which is simple in operation, mild in reaction conditions, easy to obtain raw materials, green and environmentally friendly, high in purity and high in yield.

[0013] To solve the above technical problems, the present application adopts the following technical solutions.

[0014] A synthesis method of acryloyl chloride, comprising the following steps: continuously feeding phosgene into an extractant, keeping the temperature of the extractant at-20℃-40℃, and dropping a mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor into the extractant for reaction to complete the synthesis of acryloyl chloride.

[0015] The synthesis method is further improved, and the extractant is at least one of o-dichlorobenzene, ethyl formate, ethyl propionate, propyl acetate, dimethyl carbonate, dichloromethane, trichloromethane and heptane.

[0016] The synthesis method is further improved, and the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is prepared by mixing acrylic acid, a cosolvent and a polymerization inhibitor; in the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor, the mass of the cosolvent is 0.5%-3.2% of the mass of the acrylic acid, and the mass of the polymerization inhibitor is 0.1%-2.3% of the mass of the acrylic acid.

[0017] The synthesis method is further improved, and the cosolvent is at least one of acetic acid hydrochloride, N,N-dimethylformamide hydrochloride, triethylamine hydrochloride, 4-dimethylamino pyridine hydrochloride, sodium benzoate, sodium p-toluenesulfonate and sodium salicylate.

[0018] The synthesis method is further improved, and the polymerization inhibitor is at least one of hydroquinone, resorcinol, 2,6-di-tert-butyl-p-cresol and p-tert-butyl pyrocatechol.

[0019] The synthesis method is further improved, and the temperature of the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is-20℃-40℃.

[0020] The synthesis method is further improved, and the molar ratio of the phosgene to the acrylic acid in the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is 1.05-1.2:1.

[0021] The synthesis method is further improved, and the reaction time is 2h-10h.

[0022] The synthesis method is further improved, and after the reaction is completed, the following treatment is further included: stopping the feeding of phosgene, and performing vacuum distillation on the reaction product to obtain acryloyl chloride.

[0023] Compared with the prior art, the present application has the following advantages: In view of the deficiencies of the existing synthesis method, such as easy generation of by-products, easy occurrence of side reactions, and difficulty in obtaining high-quality acryloyl chloride, the present application provides a synthesis method of acryloyl chloride, which continuously passes phosgene into an extractant, and maintains the temperature of the extractant at-20℃ to 40℃. On the one hand, more phosgene can be dissolved in the extractant, promoting the contact between phosgene and acrylic acid in the subsequent reaction process, which is conducive to reducing the consumption of phosgene and reducing the required reaction time. On the other hand, the better mass transfer effect can ensure that the reaction is carried out at a lower temperature, which not only effectively reduces the consumption of raw materials such as cosolvents and improves the reaction rate, but also effectively avoids the occurrence of side reactions and reduces the content of impurities, thereby ensuring that the subsequent reaction can be carried out at a higher reaction rate to prepare high-quality acryloyl chloride. On this basis, the mixed solution containing acrylic acid, cosolvent, and polymerization inhibitor is added dropwise into the extractant containing phosgene, and under the joint action of the extractant, cosolvent, polymerization inhibitor, and phosgene, acryloyl chloride with high yield and high purity can be obtained. Specifically, by adding a cosolvent, the solubility of acryloyl chloride and by-products (HCl) in the extractant can be adjusted. On the one hand, the cosolvent can enhance the solubility of acryloyl chloride in the extractant. On the other hand, the cosolvent can effectively reduce the solubility of HCl in the extractant, and under the action of phosgene gas flow, the generated HCl can be carried out from the extractant, thereby further reducing the content of HCl in the system. This not only allows acryloyl chloride and HCl to be completely separated, effectively avoiding the addition and self-polymerization side reactions of acryloyl chloride and HCl, but also eliminates the subsequent separation step of HCl, which is conducive to simplifying the operation and improving the synthesis efficiency. In addition, the addition of the polymerization inhibitor can also effectively avoid the addition reaction of acryloyl chloride and HCl or the self-polymerization reaction under the catalysis of strong acid. The synthesis method of acryloyl chloride of the present application uses acrylic acid as a raw material, phosgene as an acyl chloride reagent, and introduces a cosolvent, an extractant, and a polymerization inhibitor, and optimizes the temperature in the reaction process. This not only promotes the full reaction of phosgene and acrylic acid, but also effectively avoids the contact between acryloyl chloride and HCl, thereby quickly and simply preparing acryloyl chloride with high yield and high purity, wherein the product content is ≥99.5%, the yield is ≥99%, and the method has the advantages of simple operation, mild reaction conditions, easy access to raw materials, green environmental protection, high purity, high yield, etc., which can improve the product competitiveness and facilitate industrial application, and has strong industrial applicability. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0025] Figure 1 The gas phase spectrum of acryloyl chloride in Example 1 of the present application.

[0026] Figure 2 The gas chromatogram of the acryloyl chloride in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The present application is further described in detail by the following examples and drawings, but the embodiments of the present application are not limited thereto. The reagents and instruments used in the following examples are commercially available, and the product content in the examples is detected by using a gas chromatograph (GC), and the yield is calculated after measuring the normalized content of acryloyl chloride in the GC solution.

[0028] Example 1 A method for synthesizing acryloyl chloride, comprising the following steps: A 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket was charged with 40 mL of o-dichlorobenzene, and cooled to the reaction temperature (10°C) for standby. 40 g of acrylic acid (0.55 mol, 99%), 0.45 g of triethylamine hydrochloride, and 0.15 g of hydroquinone were mixed uniformly in the constant pressure dropping funnel to obtain a mixed solution A, and the solution A was cooled to the reaction temperature (10°C) by opening the jacket condenser. After the solution A was cooled to 10°C, the reactor was first charged with phosgene, and then the constant pressure dropping funnel was opened, and the flow rate was adjusted to control the drop of the solution A to be completed within 5 h, i.e. the reaction was carried out for 5 h. After the reaction solution was cooled, the product acryloyl chloride 49.29 g was obtained by vacuum distillation. Figure 1 and Figure 2 It can be seen that the acryloyl chloride can be synthesized by the present application, and the content is 99.71% and the yield is 99.28% by gas chromatography analysis.

[0029] Example 2 A method for synthesizing acryloyl chloride, comprising the following steps: A 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket was charged with 40 mL of o-dichlorobenzene, and cooled to the reaction temperature (10°C) for standby. 40 g of acrylic acid (0.55 mol, 99%), 0.45 g of triethylamine hydrochloride, and 0.15 g of hydroquinone were mixed uniformly in the constant pressure dropping funnel to obtain a mixed solution A, and the solution A was cooled to the reaction temperature (10°C) by opening the jacket condenser. After the solution A was cooled to 10°C, the reactor was first charged with phosgene, and then the constant pressure dropping funnel was opened, and the flow rate was adjusted to control the drop of the solution A to be completed within 5 h, i.e. the reaction was carried out for 5 h. After the reaction solution was cooled, the product acryloyl chloride 49.29 g was obtained by vacuum distillation.

[0030] Example 3 A method for synthesizing acryloyl chloride, comprising the following steps: Into a 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket, 40 mL of propyl acetate was added and cooled to the reaction temperature (10°C) for standby. 40 g of acrylic acid (0.55 mol, 99%) was added into the constant pressure dropping funnel, 0.25 g of 4-dimethylaminopyridine hydrochloride, 0.1 g of 2,6-di-tert-butyl-p-cresol were mixed uniformly to obtain a mixed solution A, and the jacket was opened to condense the solution A to the reaction temperature (10°C). After the solution A was cooled to 10°C, the reactor was first charged with phosgene, and then the constant pressure dropping funnel was opened, and the flow rate was adjusted to control the drop of the solution A to be completed within 5 h, i.e. the reaction was carried out for 5 h. After the reaction solution was cooled, vacuum distillation was carried out to obtain the product acryloyl chloride 49.12 g, which was analyzed by gas chromatography, the content was 99.88%, and the yield was 99.12%.

[0031] Example 4 A method for synthesizing acryloyl chloride, comprising the following steps: Into a 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket, 40 mL of propyl acetate was added and cooled to the reaction temperature (10°C) for standby. 40 g of acrylic acid (0.55 mol, 99%) was added into the constant pressure dropping funnel, 0.25 g of 4-dimethylaminopyridine hydrochloride, 0.1 g of 2,6-di-tert-butyl-p-cresol were mixed uniformly to obtain a mixed solution A, and the jacket was opened to condense the solution A to the reaction temperature (10°C). After the solution A was cooled to 10°C, the reactor was first charged with phosgene, and then the constant pressure dropping funnel was opened, and the flow rate was adjusted to control the drop of the solution A to be completed within 5 h, i.e. the reaction was carried out for 5 h. After the reaction solution was cooled, vacuum distillation was carried out to obtain the product acryloyl chloride 49.12 g, which was analyzed by gas chromatography, the content was 99.88%, and the yield was 99.12%.

[0032] Example 5 A method for synthesizing acryloyl chloride, comprising the following steps: Into a 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket, 40 mL of propyl acetate was added and cooled to the reaction temperature (10°C) for standby. 40 g of acrylic acid (0.55 mol, 99%) was added into the constant pressure dropping funnel, 0.25 g of 4-dimethylaminopyridine hydrochloride, 0.1 g of 2,6-di-tert-butyl-p-cresol were mixed uniformly to obtain a mixed solution A, and the jacket was opened to condense the solution A to the reaction temperature (10°C). After the solution A was cooled to 10°C, the reactor was first charged with phosgene, and then the constant pressure dropping funnel was opened, and the flow rate was adjusted to control the drop of the solution A to be completed within 5 h, i.e. the reaction was carried out for 5 h. After the reaction solution was cooled, vacuum distillation was carried out to obtain the product acryloyl chloride 49.12 g, which was analyzed by gas chromatography, the content was 99.88%, and the yield was 99.12%.

[0033] Example 6 A method for synthesizing acryloyl chloride, comprising the following steps: Into a 250 mL reactor equipped with a thermometer, a condenser and a constant pressure dropping funnel with a jacket, 40 mL of dichloromethane was added and cooled to the reaction temperature (0°C) for standby. Into the constant pressure dropping funnel, 40 g of acrylic acid (0.55 mol, 99%) was added, and 0.2 g of sodium benzoate and 0.2 g of 2,6-di-tert-butyl-p-cresol were mixed to obtain a mixed solution A. The jacketed condenser was opened to lower the solution A to the reaction temperature (0°C). After the solution A was lowered to 0°C, the reactor was first bubbled with phosgene, and then the constant pressure dropping funnel was opened. The flow rate was adjusted to control the dropping of the solution A to be completed within 7 h, i.e. the reaction was carried out for 7 h. After the reaction solution was cooled, the product acryloyl chloride 49.12 g was obtained by vacuum distillation. The content was 99.85% by gas chromatography analysis, and the yield was 99.10%.

[0034] Comparative Example 1 A method for synthesizing acryloyl chloride, which was basically the same as Example 1, except that the reaction temperature was -25°C and the reaction time was 36 h. The product acryloyl chloride 46.09 g was obtained, with a content of 98.8% and a yield of 92.0%.

[0035] Comparative Example 2 A method for synthesizing acryloyl chloride, which was basically the same as Example 1, except that the reaction temperature was 50°C and the reaction time was 3 h. The product acryloyl chloride 45.51 g was obtained, with a content of 96.8% and a yield of 89.1%.

[0036] Comparative Example 3 A method for synthesizing acryloyl chloride, which was basically the same as Example 1, except that the extraction agent was toluene. The product acryloyl chloride 47.00 g was obtained, with a content of 97.2% and a yield of 92.3%.

[0037] Comparative Example 4 A method for synthesizing acryloyl chloride, which was basically the same as Example 1, except that the reaction time was 20 h and the cosolvent was triethylamine. The product acryloyl chloride 46.36 g was obtained, with a content of 97.8% and a yield of 91.6%.

[0038] The results of the synthesis of acryloyl chloride in Example 1 and Comparative Examples 1-4 are shown in Table 1. Table 1 Results of Example 1 and Comparative Examples 1-4

[0039] As can be seen from the data in Table 1, when the reaction temperature is lower than -20℃, the reaction efficiency is low, the reaction time is prolonged, and the reaction yield is low; when the temperature is higher than 40℃, the reaction rate is not greatly improved, but the increase of side reactions caused by high temperature leads to the decrease of product content and reaction yield; when toluene is used instead of o-dichlorobenzene as the extractant, the reaction yield is reduced due to the solvent effect; when triethylamine is used instead of triethylamine hydrochloride as the cosolvent, not only the reaction time is prolonged, but also the low yield and low content are caused.

[0040] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified In summary, the synthesis method of acryloyl chloride in the present application uses acrylic acid as a raw material, uses phosgene as an acyl chloride reagent, and introduces a cosolvent, an extractant and a polymerization inhibitor, and optimizes the temperature in the reaction process, which not only promotes the full reaction of phosgene and acrylic acid, but also effectively avoids the contact of acryloyl chloride with HCl, thereby quickly and simply preparing acryloyl chloride with high yield and high purity, wherein the product content is ≥99.5%, the yield is ≥99%, and the method has the advantages of simple operation, mild reaction conditions, easy access to raw materials, green environmental protection, high purity, high yield, etc., can improve the product competitiveness, is convenient for industrial application, and has strong industrial applicability.

[0041] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solutions disclosed above, or modify equivalent embodiments, without departing from the spirit and technical solutions of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments according to the technical essence of the present application, all still belong to the protection scope of the technical solutions of the present application.

Claims

1. A method for the synthesis of acryloyl chloride, characterized in that, The method comprises the following steps: continuously introducing phosgene into an extractant, maintaining the temperature of the extractant at-20-40 DEG C, and adding a mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor into the extractant to react, thereby completing the synthesis of acryloyl chloride.

2. The method of synthesis of claim 1, wherein, The extractant is at least one of o-dichlorobenzene, ethyl formate, ethyl propionate, propyl acetate, dimethyl carbonate, dichloromethane, trichloromethane and heptane.

3. The method of synthesis of claim 2, wherein, The mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is prepared by mixing acrylic acid, a cosolvent and a polymerization inhibitor; the mass of the cosolvent is 0.5-3.2% of the mass of the acrylic acid, and the mass of the polymerization inhibitor is 0.1-2.3% of the mass of the acrylic acid.

4. The method of synthesis of claim 3, wherein, The cosolvent is at least one of acetamide hydrochloride, N,N-dimethylformamide hydrochloride, triethylamine hydrochloride, 4-dimethylamino pyridine hydrochloride, sodium benzoate, sodium p-toluenesulfonate and sodium salicylate.

5. The method of synthesis of claim 3, wherein, The polymerization inhibitor is at least one of hydroquinone, resorcinol, 2,6-di-tert-butyl-p-cresol and p-tert-butyl hydroquinone.

6. The method of synthesis of claim 3, wherein, The temperature of the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is-20-40 DEG C.

7. The method of synthesis according to any one of claims 1 to 6, wherein, The molar ratio of the phosgene to the acrylic acid in the mixed solution containing acrylic acid, a cosolvent and a polymerization inhibitor is 1.05-1.2:

1.

8. The method of synthesis according to any one of claims 1 to 6, wherein, The reaction time is 2-10 hours.

9. The method of synthesis according to any one of claims 1 to 6, wherein, After the reaction is completed, the method further comprises the following treatment: stopping the introduction of the phosgene, and performing vacuum distillation on the reaction product to obtain acryloyl chloride.

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