A catalyst for 2-chloropropionyl chloride acylation reaction and a preparation method thereof

Abstract

This invention discloses a catalyst for the acylation reaction of 2-chloropropionyl chloride and its preparation method, belonging to the field of catalyst technology. The catalyst is a heterogeneous solid catalyst, which can be separated from the reaction system by simple filtration after the reaction. This reduces the extensive acid and water washing processes required in traditional Friedel-Crafts acylation reactions using homogeneous Lewis acid catalysts such as aluminum trichloride, thereby reducing the discharge of large amounts of acidic wastewater at the source and improving the final product yield.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and specifically to a catalyst for the acylation reaction of 2-chloropropionyl chloride and its preparation method. Background Technology

[0002] 2-Chloropropionyl chloride is a very important organic synthesis intermediate, widely used in the synthesis of pesticides, pharmaceuticals, and fine chemicals.

[0003] In industrial production and laboratory synthesis, acylation reactions using 2-chloropropionyl chloride as the acylation reagent (such as Friedel-Crafts acylation or nucleophilic substitution acylation reactions with substrates such as amines and alcohols) are key steps in constructing carbon-carbon or carbon-heteroatom bonds. Because the 2-chloropropionyl chloride molecule contains both an active acyl chloride group and an α-chloro structure, its reactivity is high. However, in traditional acylation reactions, existing techniques generally suffer from the following drawbacks: First, traditional Friedel-Crafts acylation reactions typically use conventional Lewis acids such as anhydrous aluminum trichloride, ferric chloride, or titanium tetrachloride as catalysts. These catalysts are used in large quantities and are single-use catalysts, requiring extensive acid and water washing processes after the reaction. This not only generates large amounts of acidic wastewater but also easily leads to product hydrolysis and reduced yield. Second, the α-chlorine atom of 2-chloropropionyl chloride has a certain electrophilicity or elimination tendency. Under strong Lewis acid catalysis or high temperature conditions, it is prone to side reactions such as dechlorination, elimination, polymerization, or isomerization, resulting in decreased selectivity of the target acylation product, low product purity, and extremely difficult subsequent purification and separation. Third, although some existing complex catalysts have high activity, they are easily deactivated by absorbing water in the reaction system, and because they are miscible with the product, effective recovery and recycling of the catalyst cannot be achieved, greatly increasing production costs.

[0004] Therefore, developing a highly active, selective, easily recyclable, and environmentally friendly catalyst for the acylation reaction of 2-chloropropionyl chloride, and establishing an industrially feasible preparation method for it, are urgent technical problems to be solved in this field. Summary of the Invention

[0005] The main objective of this invention is to propose a catalyst for the acylation reaction of 2-chloropropionyl chloride and its preparation method, aiming to solve the technical problems in the prior art, such as the serious acidic wastewater pollution caused by the use of traditional Lewis acid catalysts in the acylation reaction of 2-chloropropionyl chloride, the easy hydrolysis of the product, the low purity of the product due to the easy dechlorination and elimination of the α-position chlorine atom caused by the excessive acidity of the catalyst, and the easy water absorption and deactivation of existing complex catalysts, which cannot be effectively recycled.

[0006] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride, comprising the following steps: (1) The activated 13X molecular sieve was dispersed in N,N-dimethylformamide, water-soluble nickel salt was added and stirred, then 2-aminoterephthalic acid was added and mixed evenly, and the reaction was heated; after the reaction was completed, the sieve was filtered, washed and dried to obtain the pretreated molecular sieve. (2) Under a nitrogen atmosphere, the pretreated molecular sieve is dispersed in chloroform, and ethyl isocyanate acrylate and a polymerization inhibitor are added to carry out an addition reaction; after the reaction is completed, the solid is collected by filtration, and then washed and dried to obtain urea molecular sieve. (3) Under a nitrogen atmosphere, urea molecular sieves were ultrasonically dispersed in N,N-dimethylformamide. 4-vinylpyridine and initiator were dissolved in N,N-dimethylformamide to prepare a solution, which was then added dropwise to the molecular sieve dispersion. The polymerization reaction was carried out by heating. After the reaction was completed, the product was separated, washed, dried and dispersed in N,N-dimethylformamide. Anhydrous zinc chloride was added and a complexation reaction was carried out at room temperature. After the reaction was completed, the solid product was collected by filtration, washed and dried to obtain a catalyst for the acylation reaction of 2-chloropropionyl chloride.

[0007] The catalyst prepared by the above method exhibits high catalytic activity, minimal catalytic component detachment, and good stability. It can improve the selectivity of 2-chloropropionyl chloride acylation products and suppress side reactions. The catalytic center is chemically fixed on a heterogeneous support, and can be separated by direct filtration after the reaction, facilitating recovery and reuse. This eliminates the water washing and acid washing steps in traditional processes and avoids the generation of corresponding wastewater.

[0008] This application uses 13X molecular sieve as a framework, utilizing its well-developed pores and large specific surface area to allow nickel salts to react with 2-aminoterephthalic acid on the molecular sieve surface, forming an amino coordination layer. This coordination layer not only increases the specific surface area of ​​the material, allowing the substrate to enter the pores more smoothly and contact the active center, but also introduces a large number of amino sites on the support surface. The isocyanate groups of ethyl acrylate then react with the surface amino groups to form urea bonds, simultaneously fixing polymerizable double bonds on the support surface; then, it is grafted and polymerized with 4-vinylpyridine to form a polymer chain with densely packed pyridine rings, providing a large number of sites for subsequent coordination; finally, the nitrogen atom on the pyridine ring coordinates with anhydrous zinc chloride with its lone pair electrons to obtain a Lewis acid catalytic center fixed on the solid framework.

[0009] The entire process uses anhydrous zinc chloride as the catalytic center, which is milder than aluminum trichloride. Combined with the spatial confinement of the molecular sieve channels and the effect of surface polymer chains, it can suppress side reactions such as the elimination and dechlorination of the α-position chlorine atom in 2-chloropropionyl chloride, thereby improving the selectivity of the target product. The catalytic components are sequentially fixed to the solid framework through covalent and coordinate bonds, making them less prone to loss or dissolution into the product. After the reaction, they can be recovered by filtration, eliminating the need for energy-intensive and wastewater-generating post-treatment processes.

[0010] In some embodiments, in step (1), the molar ratio of the water-soluble nickel salt to 2-aminoterephthalic acid is 1:1-1.5; the water-soluble nickel salt is at least one of nickel nitrate, nickel chloride, and nickel acetate.

[0011] Maintaining the molar ratio at 1:1-1.5 helps the nickel salt and 2-aminoterephthalic acid form a uniform and robust coordination layer on the molecular sieve surface. This ratio ensures sufficient coordination between metallic nickel and the terephthalic acid framework, resulting in stable adhesion of the coordination layer, while also retaining enough free amino groups to provide sites for subsequent double bond grafting. Excessive nickel salt will occupy too many coordination sites, reducing the number of reactive amino groups and hindering grafting; excessive 2-aminoterephthalic acid will leave uncoordinated monomers in the system, which are easily lost during washing, wasting raw materials and potentially interfering with the uniform formation of the coordination layer, resulting in a less dense structure and weak adhesion.

[0012] In some embodiments, in step (2), the mass ratio of the pretreated molecular sieve to the isocyanate ethyl acrylate is 1:0.15-0.4.

[0013] Maintaining the mass ratio at 1:0.15-0.4 ensures adequate addition of isocyanate groups to surface amino groups, resulting in a sufficient density of double bonds to provide ample initiation sites for subsequent polymerization, while avoiding excessive monomer. If the amount of ethyl isocyanate is too low, fewer urea bonds and double bonds will be formed, resulting in sparse polymer chains that cannot effectively load zinc chloride, leading to insufficient activity. If the amount is too high, excess monomer will easily remain in the pores, causing subsequent self-polymerization that blocks the pores, affecting substrate diffusion and mass transfer, and wasting raw materials.

[0014] In some embodiments, in step (2), the polymerization inhibitor is at least one of hydroquinone, p-methoxyphenol, and 2,6-di-tert-butyl-p-cresol.

[0015] Adding a polymerization inhibitor can suppress the self-polymerization of acrylate double bonds in ethyl isocyanate acrylate, allowing the isocyanate groups to preferentially add to the surface amino groups, thereby retaining the polymerizable double bonds on the molecular sieve surface, which facilitates subsequent graft polymerization with 4-vinylpyridine.

[0016] In some embodiments, in step (3), the mass of the 4-vinylpyridine is 1-3 times the mass of the urea molecular sieve.

[0017] By controlling the amount of 4-vinylpyridine to 1-3 times the mass of the urea-based molecular sieve, the length and density of the surface polymer chains can be controlled, allowing the chains to have sufficient space for extension without excessive entanglement and stacking. Appropriately long polymer chains provide enough pyridine rings to complex more zinc chloride and improve activity, while preventing excessively long chains from clogging the pores and ensuring mass transfer of the substrate near the catalytic site. If 4-vinylpyridine is in excess, the pores will be blocked by the polymer, and the catalytic activity will not decrease.

[0018] In some embodiments, in step (3), the mass ratio of anhydrous zinc chloride to urea-based molecular sieve is 0.2-0.5:1.

[0019] Limiting the mass ratio to 0.2-0.5:1 allows zinc chloride to fully coordinate and bind with the pyridine ring on the polymer chain, dispersing it more uniformly on the chain to form dispersed catalytic centers and prevent the aggregation of free zinc chloride. Combined with the aforementioned porous structure, this weakens the localized effect of Lewis acids and inhibits side reactions such as polymerization and isomerization of 2-chloropropionyl chloride. If the amount of zinc chloride is too low, the activity is insufficient, and the reaction cycle becomes longer; if it is too high, it exceeds the coordination capacity of the pyridine ring, and excess zinc chloride easily detaches and becomes miscible with the product, reducing cycle life and making product separation difficult.

[0020] In some embodiments, in step (1), the heating reaction temperature is 120-150°C, and the time is 12-24 h. Under these conditions, the nickel salt and 2-aminoterephthalic acid can fully coordinate on the surface of the molecular sieve, resulting in a dense and uniformly distributed coordination layer. If the temperature is too low or the time is too short, the reaction will be incomplete, and there will be insufficient amino sites on the surface; if the temperature is too high or the time is too long, the surface coordination layer structure may be damaged, resulting in a lack of binding sites for subsequent grafting.

[0021] In some embodiments, in step (2), the addition reaction is carried out at a temperature of 30-50°C for 6-12 hours. Under these mild conditions, the isocyanate groups can react efficiently with the surface amino groups to form urea bonds. The urea bonds contain two hydrogen bond donors and one hydrogen bond acceptor, which is beneficial for adsorbing and enriching the substrate, improving catalytic efficiency, and avoiding self-polymerization of the double bonds at high temperatures. If the temperature is too high, the double bonds are prone to premature self-polymerization, resulting in grafting failure and pore blockage; if the temperature is too low, the isocyanate groups are not active enough, the double bond grafting rate is low, and sufficient initiation sites cannot be provided.

[0022] In some embodiments, in step (3), the polymerization reaction is carried out at a temperature of 65-80°C for 8-16 hours. Under these conditions, the initiator releases free radicals, causing 4-vinylpyridine to undergo graft polymerization along surface double bonds. The resulting pyridine-containing polymer chain has a moderate length, ensuring ligand loading while preventing excessive polymer chain extension that covers the pores. If the temperature is too low, the free radical initiation efficiency is low, the polymer chain is too short, and the number of pyridine rings that can bind to the metal is limited. If the temperature is too high or the time is too long, the polymer becomes over-crosslinked, reducing the accessibility of the internal pyridine rings to zinc chloride and the substrate.

[0023] In a second aspect, this application provides a catalyst for the acylation reaction of 2-chloropropionyl chloride, said catalyst being prepared by the preparation method described in the first aspect or any embodiment of the first aspect.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention provides a catalyst for the 2-chloropropionyl chloride acylation reaction. The catalyst is a heterogeneous solid catalyst. After the reaction, it can be separated from the reaction system by simple filtration. This can reduce the large amount of acid washing and water washing required after the use of homogeneous Lewis acid catalysts such as aluminum trichloride in the traditional Friedel-Crafts acylation reaction. This not only reduces the discharge of a large amount of acidic wastewater from the source, but also improves the final yield of the product. 2) This invention uses anhydrous zinc chloride to coordinate with the pyridine ring on the polymer chain to form a complex as the catalytic center. Its Lewis acidity is relatively mild. Under the synergistic effect of the steric hindrance effect of the molecular sieve channel, the catalyst can catalyze the acylation reaction of 2-chloropropionyl chloride, effectively suppressing the side reactions such as dechlorination that are very easy to occur in the active α-chlorine atom of the 2-chloropropionyl chloride molecule under strong acid catalysis conditions, and greatly improving the selectivity of the target product. 3) In the preparation method of the present invention, the catalytic active component is coordinated and complexed on the molecular sieve framework; this binding method effectively reduces the loss of active centers during the reaction process and the mutual solubility with the reaction products, and reduces the defect of existing homogeneous complex catalysts that are very easy to absorb water and deactivate. The catalyst can be recycled and reused multiple times, which greatly reduces the industrial production cost. 4) The large specific surface area of ​​the 13X molecular sieve support and the reaction environment formed by the surface polymer chains in the catalyst of this invention allow the substrate to be better enriched near the catalytic active sites, and the reaction can be completed efficiently under relatively mild conditions, thereby effectively reducing energy consumption and shortening the reaction cycle in industrial scale-up production. While maintaining a conversion rate comparable to that of homogeneous Lewis acid catalysts, the catalyst of this invention increases the reaction selectivity from 82.1% to 95.7%, and the yield remains at 89.8% after 10 cycles of use, solving the technical problems of homogeneous catalysts being unable to be recycled, having poor selectivity, and generating large amounts of acid washing wastewater. Detailed Implementation

[0025] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0026] Example 1 A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride includes the following steps: (1) Place the 13X molecular sieve in a muffle furnace and calcine it at 350°C for 4 hours. After taking it out, place it in a desiccator and cool it to room temperature for later use. Disperse 10 parts of the above 13X molecular sieve in 150 parts of anhydrous N,N-dimethylformamide by ultrasonication to form a uniform suspension. Add 1.45 parts of nickel nitrate hexahydrate to the suspension, stir at room temperature for 20 minutes, and then add 1.08 parts of 2-aminoterephthalic acid. Heat the mixture to 130°C and react for 18 hours. After the reaction is completed, filter, wash and dry to obtain the pretreated molecular sieve. (2) Disperse 10.0 parts of pretreated molecular sieve into 100 parts of chloroform, add 2.5 parts of ethyl isocyanate acrylate dropwise under nitrogen protection, and after the dropwise addition is complete, add 0.025 parts of 2,6-di-tert-butyl-p-cresol and heat to 40°C. React for 8 hours. After the reaction is complete, filter, collect the solid product, wash and dry to obtain urea molecular sieve. (3) 10 parts of urea molecular sieve were ultrasonically dispersed in 150 parts of dry N,N-dimethylformamide. The mixture was heated to 70°C under a nitrogen atmosphere. 20 parts of 4-vinylpyridine and 0.2 parts of azobisisobutyronitrile were dissolved in 50 parts of dry N,N-dimethylformamide and then added dropwise to the molecular sieve dispersion. After the addition was complete, the reaction was continued for 10 h. After the reaction was completed, the mixture was cooled to room temperature, the solid was collected by filtration, washed and dried, and the obtained solid was dispersed in 150 parts of dry N,N-dimethylformamide. 3 parts of anhydrous zinc chloride were added, and the mixture was stirred at room temperature for 12 h. After the reaction was completed, the solid was separated by filtration, washed and dried to obtain the catalyst for the acylation reaction of 2-chloropropionyl chloride.

[0027] Example 2 A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride includes the following steps: (1) Place the 13X molecular sieve in a muffle furnace and calcine it at 350°C for 4 hours. After taking it out, place it in a desiccator and cool it to room temperature for later use. Disperse 10 parts of the above 13X molecular sieve in 150 parts of anhydrous N,N-dimethylformamide by ultrasonication to form a uniform suspension. Add 1.45 parts of nickel nitrate hexahydrate to the suspension, stir at room temperature for 20 minutes, and then add 1.08 parts of 2-aminoterephthalic acid. Heat the mixture to 130°C and react for 18 hours. After the reaction is completed, filter, wash and dry to obtain the pretreated molecular sieve. (2) Disperse 10.0 parts of pretreated molecular sieve into 100 parts of chloroform, add 2.5 parts of ethyl isocyanate acrylate dropwise under nitrogen protection, and after the dropwise addition is complete, add 0.025 parts of 2,6-di-tert-butyl-p-cresol and heat to 40°C. React for 8 hours. After the reaction is complete, filter, collect the solid product, wash and dry to obtain urea molecular sieve. (3) 10 parts of urea molecular sieve were ultrasonically dispersed in 150 parts of dry N,N-dimethylformamide. The mixture was heated to 70°C under a nitrogen atmosphere. 10 parts of 4-vinylpyridine and 0.1 parts of azobisisobutyronitrile were dissolved in 50 parts of dry N,N-dimethylformamide and then added dropwise to the molecular sieve dispersion. After the addition was complete, the reaction was continued for 10 h. After the reaction was completed, the mixture was cooled to room temperature, the solid was collected by filtration, washed and dried, and the obtained solid was dispersed in 150 parts of dry N,N-dimethylformamide. 2 parts of anhydrous zinc chloride were added, and the mixture was stirred at room temperature for 12 h. After the reaction was completed, the solid was separated by filtration, washed and dried to obtain the catalyst for the acylation reaction of 2-chloropropionyl chloride.

[0028] Example 3 A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride includes the following steps: (1) Place the 13X molecular sieve in a muffle furnace and calcine it at 350°C for 4 hours. After taking it out, place it in a desiccator and cool it to room temperature for later use. Disperse 10 parts of the above 13X molecular sieve in 150 parts of anhydrous N,N-dimethylformamide by ultrasonication to form a uniform suspension. Add 1.45 parts of nickel nitrate hexahydrate to the suspension, stir at room temperature for 20 minutes, and then add 1.08 parts of 2-aminoterephthalic acid. Heat the mixture to 130°C and react for 18 hours. After the reaction is completed, filter, wash and dry to obtain the pretreated molecular sieve. (2) Disperse 10.0 parts of pretreated molecular sieve into 100 parts of chloroform, add 2.5 parts of ethyl isocyanate acrylate dropwise under nitrogen protection, and after the dropwise addition is complete, add 0.025 parts of 2,6-di-tert-butyl-p-cresol and heat to 40°C. React for 8 hours. After the reaction is complete, filter, collect the solid product, wash and dry to obtain urea molecular sieve. (3) 10 parts of urea molecular sieve were ultrasonically dispersed in 150 parts of dry N,N-dimethylformamide. The mixture was heated to 70°C under a nitrogen atmosphere. 30 parts of 4-vinylpyridine and 0.3 parts of azobisisobutyronitrile were dissolved in 50 parts of dry N,N-dimethylformamide and then added dropwise to the molecular sieve dispersion. After the addition was complete, the reaction was continued for 10 h. After the reaction was completed, the mixture was cooled to room temperature, the solid was collected by filtration, washed and dried, and the obtained solid was dispersed in 150 parts of dry N,N-dimethylformamide. 5 parts of anhydrous zinc chloride were added, and the mixture was stirred at room temperature for 12 h. After the reaction was completed, the solid was separated by filtration, washed and dried to obtain the catalyst for the acylation reaction of 2-chloropropionyl chloride.

[0029] Comparative Example 1 A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride, the same as in Example 1, except that 4-vinylpyridine is not added, specifically including the following steps: (1) Place the 13X molecular sieve in a muffle furnace and calcine it at 350°C for 4 hours. After taking it out, place it in a desiccator and cool it to room temperature for later use. Disperse 10 parts of the above 13X molecular sieve in 150 parts of anhydrous N,N-dimethylformamide by ultrasonication to form a uniform suspension. Add 1.45 parts of nickel nitrate hexahydrate to the suspension, stir at room temperature for 20 minutes, and then add 1.08 parts of 2-aminoterephthalic acid. Heat the mixture to 130°C and react for 18 hours. After the reaction is completed, filter, wash and dry to obtain the pretreated molecular sieve. (2) Disperse 10 parts of pretreated molecular sieve into 100 parts of chloroform, add 2.5 parts of ethyl isocyanate acrylate dropwise under nitrogen protection, and after the dropwise addition is complete, add 0.025 parts of 2,6-di-tert-butyl-p-cresol and heat to 40°C. React for 8 hours. After the reaction is complete, filter, collect the solid product, wash and dry it, and disperse it in 150 parts of dry N,N-dimethylformamide. Add 3 parts of anhydrous zinc chloride and stir the reaction at room temperature for 12 hours. After the reaction is complete, filter to separate the solid, wash and dry it to obtain the catalyst for the 2-chloropropionyl chloride acylation reaction.

[0030] Comparative Example 2 A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride is the same as in Example 1, except that the catalyst is a pretreated molecular sieve, and specifically includes the following steps: (1) Place the 13X molecular sieve in a muffle furnace and calcine it at 350°C for 4 hours. After taking it out, place it in a desiccator and cool it to room temperature for later use. Disperse 10 parts of the above 13X molecular sieve in 150 parts of anhydrous N,N-dimethylformamide by ultrasonication to form a uniform suspension. Add 1.45 parts of nickel nitrate hexahydrate to the suspension, stir at room temperature for 20 minutes, and then add 1.08 parts of 2-aminoterephthalic acid. Heat the mixture to 130°C and react for 18 hours. After the reaction is completed, filter, wash and dry to obtain the pretreated molecular sieve. (2) Under a nitrogen atmosphere, 3 parts of anhydrous zinc chloride were dissolved in 150 parts of dry N,N-dimethylformamide, and 10 parts of pretreated molecular sieve were added. The mixture was stirred and reacted at room temperature for 12 h. After the reaction was completed, the solid was separated by filtration, washed and dried to obtain the catalyst for the 2-chloropropionyl chloride acylation reaction.

[0031] Comparative Example 3 A method for preparing a catalyst for the 2-chloropropionyl chloride acylation reaction is the same as in Example 1, except that the catalyst is anhydrous zinc chloride supported on a molecular sieve, and specifically includes the following steps: The 13X molecular sieve was placed in a muffle furnace and calcined at 350°C for 4 hours. After being removed, it was placed in a desiccator and cooled to room temperature for later use. Ten parts of the above 13X molecular sieve were ultrasonically dispersed in 150 parts of dry N,N-dimethylformamide, and three parts of anhydrous zinc chloride were added. The mixture was stirred and reacted at room temperature for 12 hours. After the reaction was completed, the solid was separated by filtration, washed, and dried to obtain a catalyst for the 2-chloropropionyl chloride acylation reaction.

[0032] Comparative Example 4 The catalyst used for the 2-chloropropionyl chloride acylation reaction is anhydrous zinc chloride.

[0033] Performance testing 0.5 mol of anisole, 0.55 mol of 2-chloropropionyl chloride, and 10 g of catalyst were weighed and added to 500 mL of 1,2-dichloroethane. The mixture was heated to 50 °C under nitrogen protection and stirred for 6 h. Samples were taken periodically during the reaction. After centrifugation and filtration to remove the solid catalyst, the remaining amount of anisole and the content of the target product in the reaction system were analyzed by gas chromatography. The conversion rate of anisole, the selectivity of the target product, and the yield of the target product were calculated. After the reaction was completed, the reaction system was cooled to room temperature, and the catalyst was separated by filtration. The obtained solid catalyst was washed once each with 1,2-dichloroethane (10 mL × 2), anhydrous diethyl ether (5 mL × 1), and 1,2-dichloroethane (10 mL). After vacuum drying at 80 °C for 4 h, it was directly used in the next round of reaction. The above reaction process was repeated 10 times to evaluate the cyclic stability of the catalyst. The test results are shown in Table 1. Table 1. Catalytic performance test results of catalysts used for the 2-chloropropionyl chloride acylation reaction

[0034] As can be seen from the experimental results in Table 1, the catalyst prepared in this invention for the acylation of 2-chloropropionyl chloride exhibits good catalytic activity, high selectivity, and good cycling stability. This invention uses 13X molecular sieve as a support and achieves both loading and efficient protection of the catalytic center through in-situ growth of amino MOFs, urea anchoring, pyridine polymer segment grafting, and anhydrous zinc chloride coordination complexation. The well-developed pore structure of 13X molecular sieve provides a large specific surface area, which is beneficial for substrate diffusion and mass transfer; urea bonds facilitate the adsorption and enrichment of the reaction substrate, thereby improving catalytic efficiency; and the introduction of the pyridine polymer segment microenvironment and steric hindrance effect effectively moderates the Lewis acidity of anhydrous zinc chloride, avoiding side reactions caused by traditional strong acid catalysts and ensuring the selectivity of the target product.

[0035] Comparative Example 1, lacking the addition of 4-vinylpyridine, resulted in a lack of pyridine-rich polymer segments on the molecular sieve surface. Although the adsorption and enrichment of the reaction substrate were achieved through urea bonds, the lack of pyridine-rich polymer segment support made the catalytic center prone to aggregation and loss during the reaction, leading to a significant decrease in conversion and selectivity, as well as a shorter cycle life.

[0036] Comparative Example 2 is a pretreated molecular sieve catalyst that lacks graft modification with urea bonds and pyridine polymer segments. The catalytic center (anhydrous zinc chloride) is directly supported on the amino MOF surface, which is unstable and prone to aggregation or detachment.

[0037] Comparative Example 3 directly supported anhydrous zinc chloride on 13X molecular sieves without any surface functionalization modification. The metal salt was unevenly distributed on the support surface and was extremely prone to water absorption and deactivation, resulting in the catalyst having not only the lowest conversion rate but also extremely poor ability to inhibit side reactions. This demonstrates that the construction of the functionalized interface in this invention is crucial for improving catalytic efficiency.

[0038] Comparative Example 4 directly uses anhydrous zinc chloride, which has high catalytic activity, but due to its strong acidity and homogeneous catalysis, the α-chlorine atom of 2-chloropropionyl chloride is prone to dechlorination, elimination and other side reactions.

[0039] Compared to Examples 2 and 3, Example 1 achieved a balance between polymer chain length and density by adjusting the amount of 4-vinylpyridine. Example 2 used a smaller amount, resulting in insufficient polymer chain loading and a slight decrease in catalytic activity and cycle stability. Example 3 used an excessive amount, which, while increasing the number of ligands, caused excessively long polymer chains to clog the molecular sieve channels, affecting substrate mass transfer efficiency and leading to a decrease in conversion and selectivity. Example 1 achieved a good balance between active sites and mass transfer performance.

[0040] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a catalyst for the acylation reaction of 2-chloropropionyl chloride, characterized in that, Includes the following steps: (1) The activated 13X molecular sieve was dispersed in N,N-dimethylformamide, water-soluble nickel salt was added and stirred, then 2-aminoterephthalic acid was added and mixed evenly, and the mixture was heated to carry out a solvothermal reaction; after the reaction was completed, the sieve was filtered, washed and dried to obtain the pretreated molecular sieve. (2) Under a nitrogen atmosphere, the pretreated molecular sieve is dispersed in chloroform, and ethyl isocyanate acrylate and a polymerization inhibitor are added to carry out an addition reaction; after the reaction is completed, the solid is collected by filtration, and then washed and dried to obtain urea molecular sieve. (3) Under a nitrogen atmosphere, urea molecular sieves were ultrasonically dispersed in N,N-dimethylformamide. 4-vinylpyridine and an initiator were dissolved in N,N-dimethylformamide to prepare a solution, which was then added dropwise to the molecular sieve dispersion. The polymerization reaction was carried out by heating. After the reaction was completed, the product was separated, washed, dried and dispersed in N,N-dimethylformamide. Anhydrous zinc chloride was added and a complexation reaction was carried out at room temperature. After the reaction was completed, the solid product was collected by filtration, washed and dried to obtain a catalyst for the 2-chloropropionyl chloride acylation reaction. In step (1), the molar ratio of the water-soluble nickel salt to 2-aminoterephthalic acid is 1:1-1.5; In step (2), the mass ratio of the pretreated molecular sieve to the isocyanate ethyl acrylate is 1:0.15-0.4; the polymerization inhibitor is 2,6-di-tert-butyl-p-cresol. In step (3), the mass of the 4-vinylpyridine is 1-3 times the mass of the urea molecular sieve; the mass ratio of the anhydrous zinc chloride to the urea molecular sieve is 0.2-0.5:1; and the initiator is azobisisobutyronitrile.

2. The preparation method according to claim 1, characterized in that: In step (1), the heating reaction temperature is 120-150℃ and the time is 12-24h.

3. The preparation method according to claim 1, characterized in that: In step (2), the addition reaction is carried out at a temperature of 30-50°C for 6-12 hours.

4. The preparation method according to claim 1, characterized in that: In step (3), the polymerization reaction is carried out at a temperature of 65-80°C for 8-16 hours.

5. A catalyst for the acylation reaction of 2-chloropropionyl chloride, characterized in that: It is prepared by any one of the preparation methods of claims 1-4.

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