Process for the preparation of ester products based on ionic liquid catalyst coupled to a continuous reaction flow reactor

Abstract

The application discloses a method for preparing ester products based on an ionic liquid catalyst coupled with a continuous reaction flow device, and uses an ionic liquid catalyst coupled with a continuous flow reaction technology, and specifically comprises the following steps: S1: mixing an acid and an alcohol for preparing ester products according to a proportioning ratio, and then adding an ionic liquid catalyst to obtain a mixture; S2: adding the prepared mixture into a continuous flow reactor, uniformly mixing and reacting the mixture in the continuous flow reactor at a reaction temperature of 25-240 DEG C, and obtaining ester products after the reaction is completed. The method catalytically synthesizes common ester products by introducing an ionic liquid catalyst and coupling a continuous flow reactor, the ionic liquid catalyst has higher activity, and the conversion rate of esterification is improved; the continuous flow reactor has the advantages of high heat and mass transfer efficiency, high continuous production efficiency and high operation safety coefficient, and well solves the problems of traditional kettle type reaction production, so that the continuous flow has a good prospect in industrialized production.

Description

Technical Field

[0001] This invention relates to the field of catalytic esterification synthesis, and more specifically to a method for preparing ester products based on an ionic liquid catalyst coupled with a continuous reactor. Background Technology

[0002] Ester chemicals are indispensable raw materials in modern industry, ranging from traditional solvents and plasticizers to high-end lubricants, environmentally friendly materials, and even some food additives and fragrances. They are ubiquitous in daily life and occupy a large market share. Ester products are usually produced by direct esterification or transesterification. These two methods have the advantages of high raw material conversion rate, easy purification, and short process flow. Industrial solvents such as ethyl acetate, plasticizers such as dioctyl phthalate, and fatty acid methyl esters are all synthesized by these two methods. Traditional production often uses acid catalysis, with concentrated sulfuric acid being the most common. Although effective, this method has serious drawbacks: many by-products, difficult product separation, strong corrosion that damages equipment and clogs pipelines, environmental pollution, and reduced efficiency.

[0003] With the deepening of research, novel catalysts such as zeolite molecular sieves, ion exchange resins, solid superacids, and ionic liquids have also been used in the study of catalytic synthesis of esters. For example, Yang Zhicheng et al. (Ion Exchange and Adsorption, 1998, 14(4): 7) applied macroporous cation exchange resin to the catalytic synthesis of dibutyl phthalate. The results showed that under the optimal reaction conditions, the ester yield was over 90%. Another article (Chinese Journal of Applied Chemistry, 2006, 23(4): 390-393.) reported the synthesis of a composite catalyst from SiO2 and perfluorosulfonic acid resin. The results showed that under the reaction conditions of 170℃, 4h reaction time, and an acid-to-alcohol molar ratio of 1:3, an ester yield of 97.06% was obtained. Another literature (Jiangsu Chemical Industry, 2000, (Z1): 30.) reported the use of titanium sulfate as a catalyst to prepare dimethyl terephthalate from terephthalic acid in a water bath. Under certain conditions, the conversion rate of PTA could reach 92.2%, but the amount of catalyst used was relatively large, about 3% of the mass of terephthalic acid. Another literature (Chinese Journal of Catalysis, 2007, (08): 743-748.) reported the synthesis of several pyrrolidone ionic liquids for catalyzing the reaction of butyl acetate. The results showed that under the conditions of an acid-to-alcohol ratio of 1:1.2, 120℃, and a reaction time of 1 h, a 99% ester yield could be obtained, and the amount of catalyst used was only 0.5% of the mass of the acid. Meanwhile, the literature (Journal of Hazardous Materials, 2008, 151(2-3): 847-50.) reported the use of sulfonic acid-functionalized Brønsted acidic ionic liquids for the catalytic synthesis of plasticizer esters. One or two highly active ionic liquids were selected, and it was found that the ionic liquids could be easily separated from the product with high reproducibility, and the acid conversion rate was not less than 95%. This demonstrates that various novel catalysts are increasingly being applied to ester synthesis reactions, among which ionic liquids are a promising class of new catalysts. Continuous flow reaction technology, as an emerging process simplification technique, shows great promise in the field of chemical synthesis. A study (Journal of medicinal chemistry, 2012, 55(9): 4062-4098.) reported that with the industrialization of production moving towards automation and intelligence, the research on synthetic reactions using flow chemical reactors has become a research hotspot in the field of chemical synthesis. Continuous flow reactors are widely used in the field of organic synthesis and also in the pharmaceutical and chemical industries due to their advantages such as the ability to achieve various reaction conditions, high heat and mass transfer efficiency, high continuous production efficiency, and high automation safety factor.

[0004] In recent years, the high catalytic activity exhibited by ionic liquid catalysts in esterification reactions has attracted widespread attention and is considered a highly promising research direction for solving the problems of traditional and existing solid catalysts and achieving green and efficient ester synthesis reactions. The advantages of continuous flow reaction technology are also very suitable for the application conditions of esterification reactions. If continuous flow reaction is combined with ionic liquid catalysts for the catalytic synthesis of common ester products, it is expected to further improve the ester yield, reaction efficiency, and reaction operability. However, no relevant preparation methods have been disclosed yet.

[0005] Chinese patent document CN103031217A discloses a method for preparing biodiesel from waste oil using pyrrolidone-based alkaline ionic liquids as catalysts. This method uses waste oil and alkyl alcohols as raw materials, and pyrrolidone-based ionic liquids as catalysts to catalyze the preparation of biodiesel; after the reaction, the ionic liquid and the product automatically separate phases. This prior art uses ionic liquids for preparation, which is simple, inexpensive, and has high catalyst activity with low dosage. However, it has weak adaptability to high-acid-value waste oils, and because it uses a one-step method without mentioning a pre-esterification step, it may be difficult to directly treat waste oils with excessively high acid values, and its applicable range of raw materials is narrow.

[0006] Therefore, it is necessary to propose a method for preparing ester products based on an ionic liquid catalyst coupled with a continuous flow reactor. This method uses an ionic liquid catalyst coupled with a continuous flow reactor to synthesize common ester products via direct esterification or transesterification. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for preparing ester products based on an ionic liquid catalyst coupled with a continuous reactor. The problems solved are: 1. the poor performance and large dosage of traditional catalysts; and 2. the low production efficiency and low safety factor of traditional batch reactors.

[0008] To address the aforementioned technical problems, this invention provides a method for preparing ester products based on an ionic liquid catalyst coupled with a continuous flow reactor. The method utilizes an ionic liquid catalyst coupled with a continuous flow reactor and specifically includes the following steps: S1: Mix the acid and alcohol used to prepare ester products according to the specified ratio, and then add an ionic liquid catalyst to obtain a mixture; S2: Add the mixture prepared in step S1 into a continuous flow reactor. At a reaction temperature of 25~240℃, the mixture is uniformly mixed and reacted in the continuous flow reactor for 3~5 hours. After the reaction is completed, the ester product is obtained.

[0009] Using the above technical solution, this invention synthesizes common ester products by introducing an ionic liquid catalyst and coupling it with a continuous flow reactor. The use of the ionic liquid catalyst significantly improves the efficiency and selectivity of the esterification reaction. Compared with traditional catalysts, ionic liquid catalysts have higher catalytic activity and stability, enabling efficient esterification reactions at lower temperatures and pressures, thereby reducing energy consumption and production costs. The application of continuous flow reaction technology makes the reaction process more continuous and stable, improving production efficiency while reducing the formation of by-products and improving product quality.

[0010] Preferably, the ionic liquid catalyst comprises pyrrolidone ionic liquids and / or imidazole ionic liquids.

[0011] Preferably, the preparation steps of the pyrrolidone ionic liquid are as follows: Equimolar amounts of N-alkylpyrrolidone are reacted with a protic acid at room temperature for 6-16 hours, and the pyrrolidone ionic liquid is obtained after purification by washing with cyclohexane. Specifically, the cyclohexane purification involves washing the liquid three times with cyclohexane and then drying it overnight in a vacuum drying oven at 80°C to obtain the pyrrolidone ionic liquid.

[0012] Preferably, the preparation steps of the imidazole ionic liquid are as follows: An equimolar amount of imidazole substance is reacted with a bromoalkane at 40-110°C for 4-12 hours to obtain an intermediate; then, the intermediate is reacted with an equimolar amount of a protic acid at room temperature for 6-16 hours; after purification, the imidazole ionic liquid is synthesized. Specifically, the purification involves washing three times with a detergent and then drying overnight in a vacuum drying oven at 80°C to obtain the imidazole ionic liquid.

[0013] Preferably, the protic acid used in the preparation of pyrrolidone-based ionic liquids and imidazole-based ionic liquids is one of concentrated sulfuric acid, phosphoric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, formic acid, acetic acid, propionic acid, and butyric acid; the pKa of the protic acid is -3 to 5; and the solvent used for purification is one of ethyl acetate, cyclohexane, anhydrous methanol, anhydrous diethyl ether, and toluene, with an analytical purity.

[0014] Preferably, in the preparation of imidazole ionic liquids, the bromoalkane is one of bromoethane, bromobutane, and bromohexane.

[0015] Preferably, the acid in step S1 is one of phthalic acid, terephthalic acid, sebacic acid, azelaic acid, acetic acid, and butyric acid; and the alcohol is one of methanol, ethanol, n-butanol, n-octanol, and isooctanol.

[0016] Preferably, the molar ratio of alcohol to acid in step S1 is (1~8):1.

[0017] Preferably, the amount of ionic liquid catalyst used in step S1 is 0.01% to 10% of the amount of acid.

[0018] Preferably, the ester product in step S2 includes one of plasticizer esters, polymer monomer esters, industrial solvents, and food flavorings.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention primarily addresses the problems of unsatisfactory performance, large dosage, and long reaction times in batch reactors, resulting in low catalytic efficiency associated with traditional catalysts. It introduces an ionic liquid catalyst coupled with a continuous flow reactor for the catalytic synthesis of common ester products. This not only improves the production efficiency and quality of ester products but also provides a more environmentally friendly and efficient solution for industrial production. Furthermore, this method has broad applicability and can be used to synthesize various common ester products, such as plasticizer esters, polymer monomer esters, industrial solvents, and food flavorings, meeting the needs of different fields for ester products.

[0020] (2) Ionic liquid catalysts exhibit higher activity, thus improving the conversion rate of esterification reactions. The use of ionic liquid catalysts also significantly improves the selectivity and yield of the reaction. Compared with traditional catalysts, ionic liquid catalysts have better catalytic activity and stability, enabling efficient catalysis at lower temperatures and pressures, thereby reducing energy consumption and equipment corrosion. In addition, ionic liquid catalysts are easy to recover and reuse, reducing catalyst consumption and waste generation, which aligns with the development concept of green chemistry.

[0021] (3) Comparing the catalytic effect of the continuous flow reactor with that of the traditional batch reactor, it was found that the continuous flow reactor has advantages such as high heat and mass transfer efficiency, high continuous production efficiency, and high operational safety factor. This can solve the problems of traditional batch reactor production, which makes the application of continuous flow reactor in industrial production a promising prospect. Attached Figure Description

[0022] Figure 1 The infrared spectrum of dioctyl terephthalate prepared in Specific Example 26 of this invention; Figure 2 The infrared spectrum of dioctyl phthalate prepared in specific embodiment 113 of the present invention; Figure 3 The infrared spectrum of ethyl butyrate, the product prepared in Specific Example 224 of this invention; Figure 4 The infrared spectrum of dimethyl terephthalate prepared in specific embodiment 399 of the present invention; Figure 5 The infrared spectrum of butyl acetate, the product prepared in Specific Example 464 of the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.

[0024] Unless otherwise specified, the preparation methods and usage conditions used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0025] To avoid excessive and unnecessary detail, well-known structures or functions will not be described in detail in the following embodiments. The approximate language used in the following embodiments is for quantitative purposes, indicating that variations in quantity are permissible without altering the basic function. Unless otherwise defined, the technical and scientific terms used in the following embodiments have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] Example: A method for preparing ester products based on an ionic liquid catalyst coupled with a continuous flow reactor, using ionic liquid catalyst coupled with continuous flow reactor technology, specifically including the following steps: S1: Mix the acid and alcohol used to prepare ester products according to the specified ratio, and then add an ionic liquid catalyst to obtain a mixture; The ionic liquid catalyst includes pyrrolidone ionic liquids and / or imidazole ionic liquids; The preparation steps of pyrrolidone ionic liquids are as follows: equimolar amounts of N-alkylpyrrolidone are reacted with a protic acid at room temperature for 6-16 hours, and the pyrrolidone ionic liquid is obtained after washing and purification with cyclohexane. The cyclohexane washing and purification process is as follows: the liquid is washed three times with cyclohexane and then dried overnight in a vacuum drying oven at 80°C to obtain the pyrrolidone ionic liquid. The preparation steps of imidazole ionic liquids are as follows: Equimolar amounts of imidazole substances are reacted with bromoalkane at 40-110℃ for 4-12 hours to obtain an intermediate. The intermediate is then reacted with an equimolar amount of protic acid at room temperature for 6-16 hours. After purification, the imidazole ionic liquid is synthesized. The purification process involves washing the liquid three times with a detergent and then drying it overnight in a vacuum drying oven at 80℃ to obtain the imidazole ionic liquid. The bromoalkane used in the preparation of the imidazole ionic liquid is one of bromoethane, bromobutane, or bromohexane. In some specific embodiments, the protic acid used in the preparation of pyrrolidone-based ionic liquids and imidazole-based ionic liquids is one of concentrated sulfuric acid, phosphoric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, formic acid, acetic acid, and butyric acid; the pKa of the protic acid is -3 to 5; the solvent used for purification is one of ethyl acetate, cyclohexane, anhydrous methanol, anhydrous diethyl ether, and toluene; and the purity is analytical grade. The acid in step S1 is one of phthalic acid, terephthalic acid, sebacic acid, azelaic acid, acetic acid, and butyric acid; the alcohol is one of methanol, ethanol, n-butanol, n-octanol, and isooctanol. In step S1, the molar ratio of alcohol to acid is (1~8):1; The amount of ionic liquid catalyst used in step S1 is 0.01% to 10% of the amount of acid. S2: Add the mixture prepared in step S1 into a continuous flow reactor. At a reaction temperature of 25~240℃, the mixture is uniformly mixed and reacted in the continuous flow reactor for 3~5 hours. After the reaction is completed, the ester product is obtained. The ester products in step S2 include one of the following: plasticizer esters, polymer monomer esters, industrial solvents, and food flavorings.

[0027] In some specific embodiments, the ester product is one of dioctyl terephthalate, dioctyl phthalate, ethyl butyrate, dimethyl terephthalate, and n-butyl acetate.

[0028] The following detailed description is based on 84 specific embodiments.

[0029] I. Specific Implementation Examples 1-102: These 102 specific embodiments demonstrate the preparation of the plasticizer ester dioctyl terephthalate by coupling an ionic liquid catalyst with a continuous flow catalysis. Specific embodiments 1 and 2 are conventional batch reactions, while specific embodiments 3-102 are continuous flow reactions.

[0030] The main raw materials are terephthalic acid and isooctyl alcohol, and the catalysts are imidazole ionic liquids and pyrrolidone ionic liquids. Imidazole-based ionic liquids were obtained by reacting an equimolar amount of 1-methylimidazole with a bromoalkane at 80 °C for 12 h to obtain an intermediate; then, an equimolar amount of the intermediate was reacted with sulfuric acid (pKa1≈-3) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. Pyrrolidone-based ionic liquids were obtained by reacting an equimolar amount of N-alkylpyrrolidone with a protic acid: sulfuric acid (pKa1≈-3), methanesulfonic acid (pKa=-1.9), p-toluenesulfonic acid (pKa=-2.8), formic acid (pKa=3.75), or acetic acid (pKa=4.76) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. The catalyst performance was evaluated using a continuous flow reactor under the reaction conditions shown in Table 1, yielding the ester product dioctyl terephthalate. The dioctyl terephthalate product was detected by infrared spectroscopy, such as... Figure 1 As shown, the infrared spectrum is displayed at 729 cm⁻¹. -1 775cm -1 An out-of-plane bending of the aromatic ring CH (characteristic double peak of para-substitution) appeared nearby, and at 1727 cm⁻¹ -1 This is the C=O stretching vibration of the ester group, 1115 cm⁻¹. -1 1282cm -1 This is an asymmetric stretching vibration of the ester group COC, 1380 cm⁻¹.-1 It is an aliphatic CH3 symmetric bending vibration, 1459 cm. -1 It is an aliphatic CH2 bending vibration, 1616 cm. -1 Vibrations were searched for in the C=C skeleton of aromatic rings, 2862 cm. -1 2954cm -1 These are stretching vibrations of aliphatic -CH3 and -CH2-.

[0031] Table 1 Summary of reactions in specific embodiments 1-102 Specific Implementation Number raw material Raw material molar ratio protic acid catalyst Catalyst to acid molar ratio (%) Reaction temperature (°C) Reaction time (h) Acid conversion rate (%) Product yield (%) 1 Terephthalic acid: isooctyl alcohol 1：2.7 none Tetrabutyl titanate 0.15 220 4 80.8 70.6 2 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 220 4 88.6 82.4 3 Terephthalic acid: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.05 190 3 78.5 72.3 4 Terephthalic acid: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 190 4 85.2 79.1 5 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 190 5 91.8 85.6 6 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 190 4 83.7 77.8 7 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 200 4 99.6 94.9 8 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 190 5 100 96.4 9 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 200 4 100 95.8 10 Terephthalic acid: isooctyl alcohol 1：3.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 190 4 100 94.8 11 Terephthalic acid: isooctyl alcohol 1：2.0 Formic acid N-Methylpyrrolidone carboxylate 0.05 190 3 82.3 74.5 12 Terephthalic acid: isooctyl alcohol 1：2.5 Formic acid N-Methylpyrrolidone carboxylate 0.1 190 3 86.8 77 .2 13 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.15 190 4 88.1 82.4 14 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.2 190 5 93.5 87.9 15 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.05 200 3 89.2 83.5 16 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.1 200 4 99.7 94.1 17 Terephthalic acid: isooctyl alcohol 1：3.0 Formic acid N-Methylpyrrolidone carboxylate 0.15 200 5 100 96.7 18 Terephthalic acid: isooctyl alcohol 1：3.5 Formic acid N-Methylpyrrolidone carboxylate 0.2 200 3 91.3 86 19 Terephthalic acid: isooctyl alcohol 1：2.0 Formic acid N-Methylpyrrolidone carboxylate 0.05 190 4 84.6 78.7 20 Terephthalic acid: isooctyl alcohol 1：2.5 Formic acid N-Methylpyrrolidone carboxylate 0.1 190 5 90.4 84.9 21 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0．15 190 3 79.1 73.4 22 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.2 190 4 86.9 81.2 23 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.05 200 5 96.2 91 24 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.1 200 3 88.5 83.2 25 Terephthalic acid: isooctyl alcohol 1：3.0 Formic acid N-Methylpyrrolidone carboxylate 0.15 200 4 99.2 96.1 26 Terephthalic acid: isooctyl alcohol 1：3.5 Formic acid N-Methylpyrrolidone carboxylate 0.2 200 5 100 97.8 27 Terephthalic acid: isooctyl alcohol 1：2.0 Formic acid N-Methylpyrrolidone carboxylate 0.05 190 3 71.5 66.1 28 Terephthalic acid: isooctyl alcohol 1：2.5 Formic acid N-Methylpyrrolidone carboxylate 0.1 190 4 87.3 81.6 29 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.15 190 5 92.7 87.5 30 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.2 190 3 82.9 77.1 31 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.05 200 4 93.1 87.9 32 Terephthalic acid: isooctyl alcohol 1：2.7 Formic acid N-Methylpyrrolidone carboxylate 0.1 200 5 99.4 95.5 33 Terephthalic acid: isooctyl alcohol 1：3.0 Formic acid N-Methylpyrrolidone carboxylate 0.15 200 3 90.6 85.3 34 Terephthalic acid: isooctyl alcohol 1：3.5 Formic acid N-Methylpyrrolidone carboxylate 0.2 200 4 99.4 93.7 35 Terephthalic acid: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.05 190 5 89.7 84.3 36 Terephthalic acid: isooctyl alcohol 1：2.5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 190 3 73.8 68.4 37 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.15 190 4 85.1 79.6 38 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 190 5 100 97.8 39 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.05 200 3 86.4 80.8 40 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 200 4 92.5 87.4 41 Terephthalic acid: isooctyl alcohol 1：3.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.15 200 5 99.8 95.2 42 Terephthalic acid: isooctyl alcohol 1：3.5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 200 3 90.2 84.9 43 Terephthalic acid: isooctyl alcohol 1：2.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.05 190 4 81.9 76.2 44 Terephthalic acid: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 190 5 88.6 83.1 45 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.15 190 3 75.3 69.8 46 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 190 4 83.2 77.6 47 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.05 200 5 93.1 89.1 48 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 200 5 99.4 93.4 49 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.15 200 4 93.8 88.9 50 Terephthalic acid: isooctyl alcohol 1：3.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 200 5 100 96.2 51 Terephthalic acid: isooctyl alcohol 1：2.0 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.05 190 3 69.4 64 52 Terephthalic acid: isooctyl alcohol 1：2.5 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.1 190 4 84.2 78.5 53 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.15 190 5 91.5 86.2 54 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.2 190 3 80.7 75.1 55 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.05 200 4 92.8 87.6 56 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.15 200 5 99.5 94.8 57 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.15 200 3 89.1 84 58 Terephthalic acid: isooctyl alcohol 1：3.5 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.2 200 4 99.4 94.3 59 Terephthalic acid: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.05 190 5 86.8 81.1 60 Terephthalic acid: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.1 190 3 77.2 71.6 61 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.15 190 4 89.5 84.2 62 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 190 5 99.6 93.5 63 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.05 200 3 85.3 79.8 64 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.1 200 4 91.9 86.9 65 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.15 200 5 99.2 95.4 66 Terephthalic acid: isooctyl alcohol 1：3.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 200 3 88.4 83.1 67 Terephthalic acid: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.05 190 4 79.5 73.9 68 Terephthalic acid: isooctyl alcohol 1：2.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 190 5 87.9 82.6 69 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.15 190 3 72.6 67.2 70 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 190 4 82.4 76.8 71 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.05 200 5 93.6 88.6 72 Terephthalic acid: isooctyl alcohol 1：2.7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 200 3 86.1 80.7 73 Terephthalic acid: isooctyl alcohol 1：3.0 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.15 200 4 93.1 87.2 74 Terephthalic acid: isooctyl alcohol 1：3.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 200 5 99.8 93.9 75 Terephthalic acid: isooctyl alcohol 1：2.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.05 190 3 74.1 68.6 76 Terephthalic acid: isooctyl alcohol 1：2.5 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.1 190 4 90.8 84.2 77 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.15 190 5 99.0 93.6 78 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.2 190 3 81.2 75.5 79 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.05 200 4 94.7 89.7 80 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.1 200 5 99.3 94.3 81 Terephthalic acid: isooctyl alcohol 1：3.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.15 200 3 91.4 86.2 82 Terephthalic acid: isooctyl alcohol 1：3.5 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.2 200 4 99.3 93.3 83 Terephthalic acid: isooctyl alcohol 1：2.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.05 190 5 88.2 82.7 84 Terephthalic acid: isooctyl alcohol 1：2.5 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.1 190 3 76.5 70.9 85 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.15 190 4 84.9 79.4 86 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.2 190 5 92.4 87.3 87 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.05 200 3 87.5 82 88 Terephthalic acid: isooctyl alcohol 1：2.7 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.1 200 4 93.2 88.2 89 Terephthalic acid: isooctyl alcohol 1：3.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.15 200 5 99.6 94.8 90 Terephthalic acid: isooctyl alcohol 1：3.5 methanesulfonic acid N-vinylpyrrolidone methanesulfonic acid 0.2 200 3 89.8 84.6 91 Terephthalic acid: isooctyl alcohol 1：2.0 Acetic acid N-Ethylpyrrolidone acetate 0.05 190 4 80.6 74.9 92 Terephthalic acid: isooctyl alcohol 1：2.5 Acetic acid N-Ethylpyrrolidone acetate 0.1 190 5 89.3 84 93 Terephthalic acid: isooctyl alcohol 1：2.7 Acetic acid N-Ethylpyrrolidone acetate 0.15 190 3 78.4 72.7 94 Terephthalic acid: isooctyl alcohol 1：2.7 Acetic acid N-Ethylpyrrolidone acetate 0.2 190 4 85.7 80 95 Terephthalic acid: isooctyl alcohol 1：2.7 Acetic acid N-Ethylpyrrolidone acetate 0.15 200 5 99.2 93.8 96 Terephthalic acid: isooctyl alcohol 1：2.7 Acetic acid N-Ethylpyrrolidone acetate 0.1 200 3 90.1 84.9 97 Terephthalic acid: isooctyl alcohol 1：3.0 Acetic acid N-Ethylpyrrolidone acetate 0.15 200 4 94.2 89.1 98 Terephthalic acid: isooctyl alcohol 1：3.5 Acetic acid N-Ethylpyrrolidone acetate 0.2 200 5 100 95.3 99 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.05 190 3 75.9 70.3 100 Terephthalic acid: isooctyl alcohol 1：2.7 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.1 190 4 86.5 80.8 101 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.15 190 5 100 97.6 102 Terephthalic acid: isooctyl alcohol 1：3.0 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.2 190 3 82.1 76.4 As shown in Table 1, the acid conversion rate and product yield were still relatively low in Specific Example 1, which used a conventional reactor and catalyst. For example, in Specific Example 1, using tetrabutyl titanate as a catalyst, the acid conversion rate was 80.8%, and the product yield was 70.6%. In Specific Example 2, although a conventional reactor was still used, an ionic liquid catalyst was employed, resulting in a certain improvement in both acid conversion rate and product yield, with the acid conversion rate reaching 88.6% and the product yield reaching 82.4%. When using a continuous flow reactor and an ionic liquid catalyst, extensive research into reaction conditions revealed that high acid conversion rates and product yields could be obtained. For example, in Specific Examples 3 to 102, various ionic liquid coupled continuous flow catalysis methods achieved acid conversion rates of 100% and product yields of over 95%, with the highest reaching 97.8%. This fully demonstrates that continuous flow reactors combined with ionic liquid catalysts have significant advantages in the preparation of dioctyl terephthalate, not only significantly shortening the reaction time but also effectively improving the reaction conversion rate and product yield, providing a more efficient and higher-quality method for industrial production. Furthermore, by comparing the performance of different ionic liquid catalysts, it was found that imidazole ionic liquids and pyrrolidone ionic liquids exhibited comparable catalytic activity, but imidazole ionic liquids were more convenient to recover and reuse, and thus had better prospects for industrial applications.

[0032] II. Specific Implementation Examples 103-204: The plasticizer ester dioctyl phthalate was prepared by coupling an ionic liquid catalyst with a continuous flow catalysis. Specifically, Examples 103 and 104 were conventional batch reactions, while Examples 105-204 were continuous flow reactions.

[0033] Phthalic anhydride and isooctanol are used as the main raw materials, and imidazole ionic liquids and pyrrolidone ionic liquids are used as catalysts. Imidazole-based ionic liquids were obtained by reacting an equimolar amount of 1-methylimidazole with a bromoalkane at 80 °C for 12 h to yield an intermediate; then, an equimolar amount of the intermediate was reacted with sulfuric acid (pKa1≈-3) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. Pyrrolidone-based ionic liquids were obtained by reacting an equimolar amount of N-alkylpyrrolidone with a protic acid: sulfuric acid (pKa1≈-3), methanesulfonic acid (pKa=-1.9), p-toluenesulfonic acid (pKa=-2.8), formic acid (pKa=3.75), or acetic acid (pKa=4.76) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. Catalyst performance was evaluated using a continuous flow reactor under the reaction conditions shown in Table 2, yielding the ester product dioctyl phthalate. The dioctyl phthalate product was detected by infrared spectroscopy, such as... Figure 2 As shown, the infrared spectrum is displayed at 740 cm⁻¹. -1 Nearby is the out-of-plane bending of the aromatic ring CH (characteristic peak of ortho-substitution), 1714 cm⁻¹ -1 This is the C=O stretching vibration of the ester group, 1125 cm⁻¹. -1 1278cm -1 This is an asymmetric stretching vibration of the ester group COC, 1596 cm⁻¹. -1 Vibrations were searched for in the C=C skeleton of aromatic rings, 2873 cm. -1 2963cm -1 The characteristic peaks, representing aliphatic -CH3 and -CH2- stretching vibrations, indicate the successful synthesis of dioctyl phthalate.

[0034] Table 2 Summary of reactions in specific embodiments 103-204 Specific Implementation Number raw material Raw material molar ratio protic acid catalyst Catalyst to acid molar ratio (%) Reaction temperature (°C) Reaction time (h) Acid conversion rate (%) Product yield (%) 103 Phthalic anhydride: isooctyl alcohol 1：2.5 none Tetrabutyl titanate 0.1 170 4 81.2 76.5 104 Phthalic anhydride: isooctyl alcohol 1：2.5 methanesulfonic acid N-Ocylpyrrolidone Methylsulfonate 0.1 170 4 86.9 81.2 105 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 160 3 71.2 65.5 106 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 160 4 77.8 72.1 107 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 160 5 84.3 78.9 108 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.25 170 3 79.6 74.2 109 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 170 4 86.7 81.4 110 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 170 5 94.1 88.7 111 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 180 3 99.1 93.9 112 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 180 4 99.4 96.5 113 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.25 180 5 99.8 97.1 114 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 160 3 94.1 88.1 115 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 160 4 83.3 74.8 116 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.15 160 5 87.6 82.3 117 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-methylpyrrolidine carboxylate 0.2 170 3 82.9 77.5 118 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-methylpyrrolidine carboxylate 0.25 170 4 90.1 85 119 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-methylpyrrolidine carboxylate 0.3 170 5 99.3 93.2 120 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-methylpyrrolidine carboxylate 0.1 180 3 88.7 83.5 121 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-methylpyrrolidine carboxylate 0.15 180 5 99.2 93.1 122 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-methylpyrrolidine carboxylate 0.2 180 5 99.3 95.6 123 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-methylpyrrolidine carboxylate 0.25 160 4 84.6 79.2 124 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-methylpyrrolidine carboxylate 0.3 160 5 91.5 86.4 125 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Ocylpyrrolidone acetate 0.1 170 3 86.3 80.8 126 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Ocylpyrrolidone acetate 0.15 170 4 93.7 88.6 127 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Ocylpyrrolidone acetate 0.2 170 5 100 94.5 128 Phthalic anhydride: isooctyl alcohol 1：2.5 Acetic acid N-Ocylpyrrolidone acetate 0.25 180 3 89.5 84.2 129 Phthalic anhydride: isooctyl alcohol 1：2.5 Acetic acid N-Ocylpyrrolidone acetate 0.3 180 3 99.1 93.1 130 Phthalic anhydride: isooctyl alcohol 1：2.5 Acetic acid N-Ocylpyrrolidone acetate 0.1 160 5 83.2 77.8 131 Phthalic anhydride: isooctyl alcohol 1：3.0 Acetic acid N-Ocylpyrrolidone acetate 0.15 160 3 76.4 70.8 132 Phthalic anhydride: isooctyl alcohol 1：3.0 Acetic acid N-Ocylpyrrolidone acetate 0.2 160 4 99.0 92.5 133 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-Ethylpyrrolidone carboxylate 0.25 170 5 92.6 87.8 134 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-Ethylpyrrolidone carboxylate 0.3 170 3 87.8 82.7 135 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-Ethylpyrrolidone carboxylate 0.1 180 4 94.3 89.1 136 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-Ethylpyrrolidone carboxylate 0.15 180 5 99.6 94.9 137 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-Ethylpyrrolidone carboxylate 0.2 160 3 81.5 76 138 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-Ethylpyrrolidone carboxylate 0.25 160 4 88.9 83.6 139 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-Ethylpyrrolidone carboxylate 0.3 160 5 99.7 93.8 140 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Cyclohexylpyrrolidone acetate 0.1 180 5 90.2 84.8 141 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Cyclohexylpyrrolidone acetate 0.15 180 3 84.1 78.7 142 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Cyclohexylpyrrolidone acetate 0.2 160 4 79.8 74.1 143 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Cyclohexylpyrrolidone acetate 0.25 160 5 86.4 80.9 144 Phthalic anhydride: isooctyl alcohol 1：2.0 Acetic acid N-Cyclohexylpyrrolidone acetate 0.3 170 3 82.7 77.3 145 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 170 4 91.8 86.7 146 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.15 170 5 99.2 93.3 147 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 180 3 93.6 88.5 148 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.25 180 4 99.7 96.5 149 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 160 5 88.5 83.3 150 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 180 3 85.7 80.2 151 Phthalic anhydride: isooctyl alcohol 1：3.0 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.15 180 4 92.1 87.2 152 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.2 180 5 100 94.7 153 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.25 160 3 78.4 72.9 154 Phthalic anhydride: isooctyl alcohol 1：2.0 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.3 160 4 85.2 79.7 155 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 170 5 89.9 84.7 156 Phthalic anhydride: isooctyl alcohol 1：2.5 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.15 170 3 83.3 77.9 157 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 160 4 77.9 72.2 158 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.25 160 5 84.6 79.2 159 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 170 3 80.8 75.1 160 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.1 170 4 87.5 82.3 161 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.25 180 4 99.4 92.6 162 Phthalic anhydride: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 180 3 88.1 82.9 163 Phthalic anhydride: isooctyl alcohol 1：2.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.25 180 5 100 94.6 164 Phthalic anhydride: isooctyl alcohol 1：2.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 160 5 82.3 76.7 165 Phthalic anhydride: isooctyl alcohol 1：2.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 170 3 75.6 69.9 166 Phthalic anhydride: isooctyl alcohol 1：3.0 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.15 170 4 83.2 77.8 167 Phthalic anhydride: isooctyl alcohol 1：3.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.2 160 5 90.5 85.2 168 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.25 160 3 86.2 80.8 169 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.3 170 4 92.9 87.8 170 Phthalic anhydride: isooctyl alcohol 1：2.5 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.2 170 5 99.8 94.2 171 Phthalic anhydride: isooctyl alcohol 1：2.5 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.15 180 3 94.2 89.1 172 Phthalic anhydride: isooctyl alcohol 1：3.0 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.2 180 5 100 95 173 Phthalic anhydride: isooctyl alcohol 1：3.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.25 180 5 96.4 91.6 174 Phthalic anhydride: isooctyl alcohol 1：3.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 160 3 81.7 76.2 175 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.1 160 4 78.5 73 176 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.15 160 5 85.8 80.3 177 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.2 170 3 89.3 84.1 178 Phthalic anhydride: isooctyl alcohol 1：2.0 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.25 170 5 99.1 93.3 179 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 180 5 100 95.8 180 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.2 160 3 76.8 71.1 181 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.25 160 4 83.4 77.8 182 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.3 170 5 94.8 89.7 183 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 180 4 89.6 84.3 184 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 180 5 99.6 92.8 185 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 160 3 79.1 73.5 186 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.25 160 4 85.9 80.4 187 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 170 5 99.6 93.1 188 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.1 170 4 90.7 85.6 189 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.15 170 5 99.2 93.4 190 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.2 180 3 95.1 90.2 191 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.25 180 4 100 95.4 192 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.3 160 5 86.8 81.2 193 Phthalic anhydride: isooctyl alcohol 1：3.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 180 4 91.4 86.3 194 Phthalic anhydride: isooctyl alcohol 1：3.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.15 180 5 100 95.6 195 Phthalic anhydride: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 160 5 83.6 77.9 196 Phthalic anhydride: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.25 160 3 75.2 69.6 197 Phthalic anhydride: isooctyl alcohol 1：2.0 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 170 4 87.9 82.5 198 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 160 5 84.9 79.5 199 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.15 160 3 77.5 71.9 200 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 170 4 89.2 84 201 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.25 170 5 95.9 91.1 202 Phthalic anhydride: isooctyl alcohol 1：3.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 180 4 100 97.4 203 Phthalic anhydride: isooctyl alcohol 1：2.0 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 180 4 97.3 92.6 204 Phthalic anhydride: isooctyl alcohol 1：2.5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.15 180 5 100 96.2 As shown in Table 2, in Specific Example 103, a conventional reactor and the conventional catalyst tetrabutyl titanate were used, resulting in a relatively low acid conversion rate of 81.2% and a product yield of 76.5%. In Specific Example 104, although a conventional reactor was still used, an ionic liquid catalyst was employed, leading to improvements in both acid conversion and product yield, with an acid conversion rate reaching 86.9% and a product yield of 81.2%. When a continuous flow reactor was used and an ionic liquid catalyst was employed, both acid conversion and product yield were significantly improved. For example, in Specific Examples 110 to 114, the lowest acid conversion rate was 94.1%, and the highest reached 99.8%; the lowest product yield was 88.1%, and the highest reached 97.1%. In Specific Examples 163-173, different types of pyrrolidone-based ionic liquids were used as catalysts, resulting in acid conversion rates generally above 90% and significantly improved product yields, reaching a maximum of 95%. In particular, in specific embodiments 127, 152, 163, 172, 179, 191, 194, 202, and 204, the acid conversion rate reached 100%, and the product yield remained at a high level, reaching a maximum of 97.4%. This indicates that a continuous flow reactor combined with an ionic liquid catalyst also has significant advantages in the preparation of dioctyl phthalate, effectively shortening the reaction time and improving the conversion rate and product yield, providing strong support for industrial production. Furthermore, different ionic liquid catalysts exhibit varying catalytic effects, and the appropriate catalyst can be selected based on specific circumstances in actual production.

[0035] III. Specific Implementation Examples 205-304: Ethyl butyrate of fragrance was prepared by coupling an ionic liquid catalyst with a continuous flow catalysis. Specific examples 205 and 206 are conventional batch reactions, while examples 207-304 are continuous flow reactions.

[0036] Using butyric acid and isooctanol as raw materials, and imidazole and pyrrolidone ionic liquids as catalysts, the imidazole ionic liquid was reacted with an equimolar amount of 1-methylimidazolium and a bromoalkane at 80°C for 12 h to obtain an intermediate. An equimolar amount of the intermediate was then reacted with sulfuric acid (pKa1≈-3) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. The pyrrolidone ionic liquid was reacted with an equimolar amount of N-alkylpyrrolidone and a protic acid: sulfuric acid (pKa1≈-3), methanesulfonic acid (pKa=-1.9), p-toluenesulfonic acid (pKa=-2.8), formic acid (pKa=3.75), or acetic acid (pKa=4.76) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. The catalyst performance was evaluated using a continuous flow reactor under the reaction conditions shown in Table 3, yielding the ester product ethyl butyrate. The ethyl butyrate product was detected by infrared spectroscopy. Figure 3 As shown, the infrared spectrum is displayed at 1117 cm⁻¹.-1 1268cm -1 This is the stretching vibration of the ester group COC, 1650 cm⁻¹. -1 This is the C=O stretching vibration of the ester group, 1360 cm⁻¹ -1 It is a -CH3 symmetrical bending vibration, 2962 cm. -1 2834cm -1 These are stretching vibrations of aliphatic -CH3 and -CH2-; these characteristic peaks indicate that ethyl butyrate was successfully synthesized.

[0037] Table 3 Summary of reactions in specific embodiments 205-304 Specific Implementation Number raw material Raw material molar ratio protic acid catalyst Catalyst to acid molar ratio (%) Reaction temperature (°C) Reaction time (h) Acid conversion rate (%) Product yield (%) 205 Butyric acid: ethanol 1：1.5 none p-Toluenesulfonic acid 0.2 110 4 78.4 70.8 206 Butyric acid: ethanol 1：1.5 methanesulfonic acid N-Ocylpyrrolidone Methylsulfonate 0.2 110 4 85.4 78.1 207 Butyric acid: ethanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 100 3 72.2 64.5 208 Butyric acid: ethanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 100 3 77.4 72.8 209 Butyric acid: ethanol 1：1.2 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 100 4 83.0 75.4 210 Butyric acid: ethanol 1：1.2 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 100 4 78.6 74.2 211 Butyric acid: ethanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 110 4 85.7 80.4 212 Butyric acid: ethanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 110 3 82.1 76.7 213 Butyric acid: ethanol 1：1.4 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 110 4 85.4 77.9 214 Butyric acid: ethanol 1：1.4 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 110 3 92.4 87.3 215 Butyric acid: ethanol 1：1.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 110 4 99.4 95.2 216 Butyric acid: ethanol 1：1.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 120 4 100 96.4 217 Butyric acid: ethanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 120 4 80.3 74.8 218 Butyric acid: ethanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 120 4 88.6 81.3 219 Butyric acid: ethanol 1：1.2 Formic acid N-Methylpyrrolidone carboxylate 0.3 110 4 82.9 77.5 220 Butyric acid: ethanol 1：1.2 Formic acid N-Methylpyrrolidone carboxylate 0.3 110 4 92.1 86.1 221 Butyric acid: ethanol 1：1.3 Formic acid N-Methylpyrrolidone carboxylate 0.3 110 4 99.3 93.1 222 Butyric acid: ethanol 1：1.3 Formic acid N-Methylpyrrolidone carboxylate 0.1 100 3 86.7 81.5 223 Butyric acid: ethanol 1：1.4 Formic acid N-Methylpyrrolidone carboxylate 0.1 100 3 96.2 91.1 224 Butyric acid: ethanol 1：1.4 Formic acid N-Methylpyrrolidone carboxylate 0.2 100 4 100 97.6 225 Butyric acid: ethanol 1：1.5 Formic acid N-Methylpyrrolidone carboxylate 0.1 100 4 84.6 78.2 226 Butyric acid: ethanol 1：1.5 Formic acid N-Methylpyrrolidone carboxylate 0.1 110 4 90.5 86.4 227 Butyric acid: ethanol 1：1.1 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.1 110 3 86.3 82.8 228 Butyric acid: ethanol 1：1.1 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.1 110 4 93.7 88.4 229 Butyric acid: ethanol 1：1.2 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 110 3 99.4 93.7 230 Butyric acid: ethanol 1：1.2 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 110 3 89.5 84.6 231 Butyric acid: ethanol 1：1.3 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 120 4 99.8 93.5 232 Butyric acid: ethanol 1：1.3 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 120 4 83.2 76.8 233 Butyric acid: ethanol 1：1.4 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 120 4 77.2 70.4 234 Butyric acid: ethanol 1：1.4 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 110 4 83.9 76.5 235 Butyric acid: ethanol 1：1.5 Acetic acid N-Ethylpyrrolidone acetate 0.3 110 4 99.1 93.8 236 Butyric acid: ethanol 1：1.5 Acetic acid N-Ethylpyrrolidone acetate 0.3 110 4 87.8 82.7 237 Butyric acid: ethanol 1：1.1 Acetic acid N-Ethylpyrrolidone acetate 0.1 100 3 94.3 89.1 238 Butyric acid: ethanol 1：1.5 Acetic acid N-Ethylpyrrolidone acetate 0.3 110 4 100 95.9 239 Butyric acid: ethanol 1：1.1 Acetic acid N-Ethylpyrrolidone acetate 0.1 100 4 81.5 76 240 Butyric acid: ethanol 1：1.2 Acetic acid N-Ethylpyrrolidone acetate 0.1 100 4 88.9 83.6 241 Butyric acid: ethanol 1：1.4 Acetic acid N-Ethylpyrrolidone acetate 0.2 110 4 99.7 93.8 242 Butyric acid: ethanol 1：1.3 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 110 3 92.2 86.8 243 Butyric acid: ethanol 1：1.3 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 110 4 84.1 78.7 244 Butyric acid: ethanol 1：1.4 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 110 3 78.8 74.1 245 Butyric acid: ethanol 1：1.4 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 110 3 87.4 80.4 246 Butyric acid: ethanol 1：1.2 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 120 3 82.7 77.3 247 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 120 4 91.8 86.7 248 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 120 4 100 96.3 249 Butyric acid: ethanol 1：1.4 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 110 4 99.2 92.5 250 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 120 4 99.5 93.4 251 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 110 4 88.5 83.3 252 Butyric acid: ethanol 1：1.3 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 100 3 85.5 80.1 253 Butyric acid: ethanol 1：1.4 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 100 3 92.1 87.2 254 Butyric acid: ethanol 1：1.4 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.2 100 4 100 96.7 255 Butyric acid: ethanol 1：1.5 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 100 4 88.4 80.9 256 Butyric acid: ethanol 1：1.5 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 110 4 99.1 93.3 257 Butyric acid: ethanol 1：1.1 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 110 3 89.9 84.7 258 Butyric acid: ethanol 1：1.1 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 110 4 83.3 77.9 259 Butyric acid: ethanol 1：1.2 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 110 3 87.9 81.2 260 Butyric acid: ethanol 1：1.2 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 110 3 90.6 86.2 261 Butyric acid: ethanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 120 3 99.1 93.1 262 Butyric acid: ethanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 120 4 87.5 82.3 263 Butyric acid: ethanol 1：1.4 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 120 4 95.4 90.6 264 Butyric acid: ethanol 1：1.4 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 110 4 88.1 82.9 265 Butyric acid: ethanol 1：1.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 110 4 90.4 85.6 266 Butyric acid: ethanol 1：1.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 110 4 99.8 94.2 267 Butyric acid: ethanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 100 3 75.6 69.9 268 Butyric acid: ethanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 100 3 83.2 77.8 269 Butyric acid: ethanol 1：1.2 Formic acid N-Ethylpyrrolidone carboxylate 0.1 100 4 86.2 80.8 270 Butyric acid: ethanol 1：1.2 Formic acid N-Ethylpyrrolidone carboxylate 0.1 100 4 90.5 83.8 271 Butyric acid: ethanol 1：1.3 Formic acid N-Ethylpyrrolidone carboxylate 0.1 110 4 92.9 87.8 272 Butyric acid: ethanol 1：1.3 Formic acid N-Ethylpyrrolidone carboxylate 0.1 110 3 90.8 84.2 273 Butyric acid: ethanol 1：1.4 Formic acid N-Ethylpyrrolidone carboxylate 0.1 110 4 94.2 89.1 274 Butyric acid: ethanol 1：1.4 Formic acid N-Ethylpyrrolidone carboxylate 0.2 110 4 100 95.4 275 Butyric acid: ethanol 1：1.5 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.2 110 3 96.4 91.6 276 Butyric acid: ethanol 1：1.5 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.2 120 3 99.2 94.1 277 Butyric acid: ethanol 1：1.1 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 110 4 78.5 73 278 Butyric acid: ethanol 1：1.1 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 110 4 85.8 80.3 279 Butyric acid: ethanol 1：1.2 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 120 4 89.3 84.1 280 Butyric acid: ethanol 1：1.2 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 120 4 96.1 91.3 281 Butyric acid: ethanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 110 4 100 95.8 282 Butyric acid: ethanol 1：1.3 Acetic acid N-Methylpyrrolidone acetate 0.1 100 3 86.8 81.1 283 Butyric acid: ethanol 1：1.4 Acetic acid N-Methylpyrrolidone acetate 0.1 100 3 88.4 82.8 284 Butyric acid: ethanol 1：1.4 Acetic acid N-Methylpyrrolidone acetate 0.1 100 4 90.8 86.7 285 Butyric acid: ethanol 1：1.5 Formic acid N-Ocylpyrrolidone carboxylate 0.1 100 4 93.6 88.3 286 Butyric acid: ethanol 1：1.5 Formic acid N-Ocylpyrrolidone carboxylate 0.1 110 4 99.4 93.2 287 Butyric acid: ethanol 1：1.1 Formic acid N-Ocylpyrrolidone carboxylate 0.1 110 3 79.1 73.5 288 Butyric acid: ethanol 1：1.1 Formic acid N-Ocylpyrrolidone carboxylate 0.1 110 4 85.9 80.4 289 Butyric acid: ethanol 1：1.2 Formic acid N-Ocylpyrrolidone carboxylate 0.2 110 4 93.2 88.3 290 Butyric acid: ethanol 1：1.2 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.2 110 3 90.7 85.6 291 Butyric acid: ethanol 1：1.3 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.3 120 4 100 95.1 292 Butyric acid: ethanol 1：1.3 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.3 120 3 95.1 90.2 293 Butyric acid: ethanol 1：1.4 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.3 120 4 100 96.4 294 Butyric acid: ethanol 1：1.4 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.3 110 4 86.8 81.2 295 Butyric acid: ethanol 1：1.5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 110 4 91.4 86.3 296 Butyric acid: ethanol 1：1.5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 120 4 99.8 95.6 297 Butyric acid: ethanol 1：1.1 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 100 4 83.6 77.9 298 Butyric acid: ethanol 1：1.1 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 100 3 75.2 69.6 299 Butyric acid: ethanol 1：1.2 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 100 4 87.9 82.5 300 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 110 4 84.9 79.5 301 Butyric acid: ethanol 1：1.2 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 100 4 77.5 71.9 302 Butyric acid: ethanol 1：1.3 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 110 4 89.2 84 303 Butyric acid: ethanol 1：1.4 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 110 4 99.5 93.1 304 Butyric acid: ethanol 1：1.4 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 110 4 99.7 96.0 As shown in Table 3, in Specific Example 205, a conventional reactor and conventional catalyst were used for p-toluenesulfonic acid. The acid conversion rate was 78.4%, and the product yield was 70.8%, both relatively low. In Specific Example 206, although a conventional reactor was used, the use of an ionic liquid catalyst improved both the acid conversion rate and product yield, reaching 85.4% and 78.1%. When a continuous flow reactor coupled with an ionic liquid catalyst was used, the acid conversion rate and product yield were significantly improved. For example, in Specific Examples 211 to 221, the acid conversion rate ranged from a minimum of 80.3% to a maximum of 100%; the product yield ranged from a minimum of 74.8% to a maximum of 96.4%. In Specific Examples 270-276, using different types of ionic liquid catalysts, the acid conversion rate was generally above 90%, and the product yield was also significantly improved, reaching a maximum of 95.4%. In particular, in specific embodiments 216, 224, 238, 248, 254, and 274, the acid conversion rate reached 100%, and the product yield remained at a high level, reaching a maximum of 97.6%. Especially in specific embodiments 219-226, the catalyst type and dosage were further optimized, and the acid conversion rate reached 100% in all cases, with the product yield remaining at a high level, reaching a maximum of 97.6%. These data fully demonstrate the high efficiency and superiority of ionic liquid catalyst coupled with a continuous flow reactor in the preparation of ethyl butyrate. This indicates that the combination of a continuous flow reactor and an ionic liquid catalyst has significant advantages in the preparation of ethyl butyrate, effectively shortening the reaction time, improving the reaction conversion rate and product yield, and providing a strong guarantee for industrial production.

[0038] IV. Specific Implementation Examples 305-402: The polymer monomer ester dimethyl terephthalate was prepared by coupling an ionic liquid catalyst with a continuous flow catalysis. Specifically, Examples 305 and 306 are conventional batch reactions, while Examples 307-402 are continuous flow reactions.

[0039] Using terephthalic acid and methanol as main raw materials, and imidazole and pyrrolidone ionic liquids as catalysts, the imidazole ionic liquid was reacted with an equimolar amount of 1-methylimidazolium and a bromoalkane at 80°C for 12 h to obtain an intermediate. The intermediate was then reacted with an equimolar amount of sulfuric acid (pKa1≈-3) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. The pyrrolidone ionic liquid was reacted with an equimolar amount of N-alkylpyrrolidone and a protic acid: sulfuric acid (pKa1≈-3), methanesulfonic acid (pKa=-1.9), p-toluenesulfonic acid (pKa=-2.8), formic acid (pKa=3.75), or acetic acid (pKa=4.76) at room temperature for 12 h, followed by purification with cyclohexane to obtain the target ionic liquid. The catalyst performance was evaluated using a continuous flow reactor under the reaction conditions shown in Table 4, yielding the ester product dimethyl terephthalate. The dimethyl terephthalate product was detected by infrared spectroscopy. Figure 4 As shown, the infrared spectrum is displayed at 727 cm⁻¹. -1 811cm -1 The aromatic ring CH is out-of-plane bent (characteristic double peak of para-substitution), 1723 cm⁻¹ -1 This is the C=O stretching vibration of the ester group, 1113 cm⁻¹ -1 1258cm -1 This is an asymmetric stretching vibration of the ester group COC, 1411 cm⁻¹. -1 1441cm -1 This is the symmetric bending vibration of -CH3 in methyl ester, 1502 cm⁻¹ -1 The peaks at 2840 and 2956 represent the symmetric and asymmetric stretching vibrations of the -CH3 group, respectively, indicating the successful synthesis of dimethyl terephthalate.

[0040] Table 4 Summary of reactions in specific embodiments 305-402 Specific Implementation Number raw material Raw material molar ratio protic acid catalyst Catalyst to acid molar ratio (%) Reaction temperature (°C) Reaction time (h) Acid conversion rate (%) Product yield (%) 305 Terephthalic acid: Methanol 1：6 none Zinc acetate 0.2 160 4 80.1 72.2 306 Terephthalic acid: Methanol 1：6 methanesulfonic acid N-Ocylpyrrolidone Methylsulfonate 0.2 160 4 88.1 79.4 307 Terephthalic acid: Methanol 1:5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 140 4 84.2 80.1 308 Terephthalic acid: Methanol 1：6 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.2 150 5 96.5 92.8 309 Terephthalic acid: Methanol 1：7 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 160 5 100 97.3 310 Terephthalic acid: Methanol 1：8 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.1 140 5 82.7 79.5 311 Terephthalic acid: Methanol 1：5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 150 4 89.4 85 312 Terephthalic acid: Methanol 1：6 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 160 4 99.1 93.7 313 Terephthalic acid: Methanol 1：7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.1 150 5 94.8 91.2 314 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 160 5 100 95.9 315 Terephthalic acid: Methanol 1：5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 140 4 86 82.4 316 Terephthalic acid: Methanol 1：6 methanesulfonate N-Ethylpyrrolidone methanesulfonic acid 0.1 150 4 90.3 87.1 317 Terephthalic acid: Methanol 1：7 methanesulfonate N-vinylpyrrolidone methanesulfonate 0.3 160 5 100 96.8 318 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 140 5 81.5 78 319 Terephthalic acid: Methanol 1：6 Formic acid N-Methylpyrrolidone carboxylate 0.3 160 5 95.4 90.4 320 Terephthalic acid: Methanol 1：6 Formic acid N-Ocylpyrrolidone carboxylate 0.1 150 4 93.7 89.5 321 Terephthalic acid: Methanol 1：7 Formic acid N-Ethylpyrrolidone carboxylate 0.3 140 4 85.1 81.3 322 Terephthalic acid: Methanol 1：8 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 160 5 99.1 94.2 323 Terephthalic acid: Methanol 1：5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 150 5 95.6 92.1 324 Terephthalic acid: Methanol 1：6 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.3 140 5 83.9 80.7 325 Terephthalic acid: Methanol 1：7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 160 5 100 98.1 326 Terephthalic acid: Methanol 1：8 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 150 3 91.8 88 327 Terephthalic acid: Methanol 1：8 methanesulfonate N-Ethylpyrrolidone methanesulfonic acid 0.3 160 4 99.3 94.5 328 Terephthalic acid: Methanol 1：6 methanesulfonate N-vinylpyrrolidone methanesulfonate 0.1 140 5 80.4 76.9 329 Terephthalic acid: Methanol 1：7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 150 5 94.1 90.3 330 Terephthalic acid: Methanol 1：8 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.3 160 5 100 97.5 331 Terephthalic acid: Methanol 1：5 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 140 4 88.2 84.7 332 Terephthalic acid: Methanol 1：6 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.1 160 5 92.5 89 333 Terephthalic acid: Methanol 1：7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 150 5 99.4 93.8 334 Terephthalic acid: Methanol 1：8 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 150 3 87.3 83.8 335 Terephthalic acid: Methanol 1：8 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.2 160 4 97.8 94.5 336 Terephthalic acid: Methanol 1：6 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 140 5 84.6 81.2 337 Terephthalic acid: Methanol 1：7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 140 4 82.9 79.6 338 Terephthalic acid: Methanol 1：8 methanesulfonate N-Ethylpyrrolidone methanesulfonic acid 0.2 150 5 99.6 93.1 339 Terephthalic acid: Methanol 1：8 methanesulfonate N-vinylpyrrolidone methanesulfonate 0.3 160 5 100 96.3 340 Terephthalic acid: Methanol 1：6 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 150 4 89.1 85.5 341 Terephthalic acid: Methanol 1：7 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.2 140 5 85.7 82.3 342 Terephthalic acid: Methanol 1：8 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 150 4 95.4 91.6 343 Terephthalic acid: Methanol 1：5 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.1 160 4 91.9 88.2 344 Terephthalic acid: Methanol 1：6 Formic acid N-Cyclohexylpyrrolidone paraformate 0.2 140 5 86.8 83.3 345 Terephthalic acid: Methanol 1：7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 150 5 99.3 93.6 346 Terephthalic acid: Methanol 1：8 Formic acid N-Cyclohexylpyrrolidone carboxylate 0.1 140 4 81.2 77.9 347 Terephthalic acid: Methanol 1：5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 150 5 94.5 90.7 348 Terephthalic acid: Methanol 1：6 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 160 4 99.4 94.5 349 Terephthalic acid: Methanol 1：7 Formic acid N-Ethylpyrrolidone carboxylate 0.1 140 4 79.8 76.6 350 Terephthalic acid: Methanol 1：8 Formic acid N-vinylpyrrolidone carboxylate 0.2 150 4 92.1 88.4 351 Terephthalic acid: Methanol 1：5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 160 5 100 97 352 Terephthalic acid: Methanol 1：6 Acetic acid N-Methylpyrrolidone acetate 0.1 140 5 83.4 80.1 353 Terephthalic acid: Methanol 1：7 Acetic acid N-Ocylpyrrolidone acetate 0.2 150 4 93.9 90.1 354 Terephthalic acid: Methanol 1：8 Acetic acid N-Ethylpyrrolidone acetate 0.3 160 4 99.6 94.2 355 Terephthalic acid: Methanol 1：5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 150 5 92.3 88.6 356 Terephthalic acid: Methanol 1：6 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 140 4 85.5 82.1 357 Terephthalic acid: Methanol 1：7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.3 150 5 97.5 93.6 358 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.1 140 5 82.1 78.8 359 Terephthalic acid: Methanol 1：5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 160 5 99.2 95.7 360 Terephthalic acid: Methanol 1：6 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.3 150 4 95.1 91.3 361 Terephthalic acid: Methanol 1：7 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.1 140 4 79.3 76.1 362 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 150 5 95.8 92 363 Terephthalic acid: Methanol 1：5 Formic acid N-Methylpyrrolidone carboxylate 0.3 140 4 87.9 84.4 364 Terephthalic acid: Methanol 1：6 Formic acid N-Ocylpyrrolidone carboxylate 0.1 160 5 99.2 93.3 365 Terephthalic acid: Methanol 1：7 Formic acid N-Ethylpyrrolidone carboxylate 0.2 150 4 92.4 88.7 366 Terephthalic acid: Methanol 1：8 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 140 5 88.6 85.1 367 Terephthalic acid: Methanol 1：5 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 160 4 93.7 90 368 Terephthalic acid: Methanol 1：6 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.2 150 5 96.3 92.4 369 Terephthalic acid: Methanol 1：7 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 160 5 100 97.8 370 Terephthalic acid: Methanol 1：8 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.1 150 4 89.7 86.1 371 Terephthalic acid: Methanol 1：5 methanesulfonate N-Ethylpyrrolidone methanesulfonic acid 0.2 140 5 84 80.6 372 Terephthalic acid: Methanol 1：6 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.3 160 4 99.1 95.3 373 Terephthalic acid: Methanol 1：7 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 150 5 94.3 90.5 374 Terephthalic acid: Methanol 1：8 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.2 140 4 86.3 82.8 375 Terephthalic acid: Methanol 1：5 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.3 150 4 96.8 93 376 Terephthalic acid: Methanol 1：6 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.1 140 4 80.6 77.4 377 Terephthalic acid: Methanol 1：7 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.2 160 5 99.7 96.2 378 Terephthalic acid: Methanol 1：8 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.3 150 5 97 93.1 379 Terephthalic acid: Methanol 1：5 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.1 140 5 83.8 80.4 380 Terephthalic acid: Methanol 1：6 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 160 4 99.2 94.3 381 Terephthalic acid: Methanol 1：7 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 150 4 96.5 92.6 382 Terephthalic acid: Methanol 1：8 Acetic acid N-Ethylpyrrolidone acetate 0.1 160 5 94.9 91.1 383 Terephthalic acid: Methanol 1：5 Acetic acid N-vinylpyrrolidone acetate 0.2 140 4 85.1 81.7 384 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 150 5 99.5 93.5 385 Terephthalic acid: Methanol 1：7 sulfuric acid N-Methylpyrrolidone hydrogen sulfate 0.1 140 5 82.5 79.2 386 Terephthalic acid: Methanol 1：8 sulfuric acid N-Ocylpyrrolidone hydrogen sulfate 0.2 160 5 100 97.2 387 Terephthalic acid: Methanol 1：5 sulfuric acid N-Ethylpyrrolidone hydrogen sulfate 0.3 150 4 94.2 90.4 388 Terephthalic acid: Methanol 1：6 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.1 140 4 81.9 78.6 389 Terephthalic acid: Methanol 1：7 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.2 160 4 99.4 95 390 Terephthalic acid: Methanol 1：8 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.3 150 5 99.1 94.2 391 Terephthalic acid: Methanol 1：5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.1 150 4 88.4 84.9 392 Terephthalic acid: Methanol 1：6 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 140 5 87.5 84 393 Terephthalic acid: Methanol 1：7 methanesulfonic acid N-Ethylpyrrolidone methanesulfonic acid 0.3 160 4 99.3 95.6 394 Terephthalic acid: Methanol 1：8 methanesulfonic acid N-vinylpyrrolidone methanesulfonate 0.1 150 5 91.4 87.7 395 Terephthalic acid: Methanol 1：6 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 160 5 99.6 96.1 396 Terephthalic acid: Methanol 1：6 p-Toluenesulfonic acid N-Methylpyrrolidone p-Toluenesulfonic Acid 0.3 140 5 89.2 85.6 397 Terephthalic acid: Methanol 1：7 p-Toluenesulfonic acid N-Ocylpyrrolidone p-Toluenesulfonic Acid 0.2 150 5 100 96.4 398 Terephthalic acid: Methanol 1：8 p-Toluenesulfonic acid N-Ethylpyrrolidone p-Toluenesulfonic Acid 0.2 140 4 94.7 89.3 399 Terephthalic acid: Methanol 1：5 p-Toluenesulfonic acid N-Cyclohexylpyrrolidone p-Toluenesulfonic Acid 0.3 160 5 99.4 97.6 400 Terephthalic acid: Methanol 1：6 sulfuric acid N-vinylpyrrolidone hydrogen sulfate 0.1 150 4 88.9 85.3 401 Terephthalic acid: Methanol 1：7 sulfuric acid N-Cyclohexylpyrrolidone hydrogen sulfate 0.2 140 5 86.9 83.4 402 Terephthalic acid: Methanol 1：8 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 160 4 100 96.3 As shown in Table 4, in Specific Example 305, using a conventional reactor and the conventional catalyst tetrabutyl titanate, the acid conversion rate was 80.1%, and the product yield was 72.2%, both at relatively low levels. In Specific Example 306, although a conventional reactor was still used, the use of the ionic liquid catalyst N-octylpyrrolidone methanesulfonate improved the acid conversion rate to 88.1% and the product yield to 79.4%, showing some improvement. In Specific Examples 311-317, using different types of pyrrolidone and imidazole ionic liquids as catalysts and a continuous flow reactor, the acid conversion rate was consistently above 86%, and the product yield was significantly improved, reaching a maximum of 96.8%. In Specific Examples 384-402, different catalysts and reaction conditions were further explored. Under different catalyst conditions, 100% conversion was achieved, and the product yield remained stable above 95%, reaching a maximum of 97.2%. These data fully demonstrate that ionic liquid catalyst coupled with a continuous flow reactor is highly efficient and superior in the preparation of the polymer monomer ester dimethyl terephthalate.

[0041] V. Specific Implementation Examples 403-491: The industrial solvent n-butyl acetate is prepared by coupling an ionic liquid catalyst with a continuous flow catalysis. Specific examples 403 and 404 are conventional batch reactions, while specific examples 405-491 are continuous flow reactions.

[0042] Acetic acid and n-butanol were used as main raw materials, and imidazole and pyrrolidone ionic liquids were used as catalysts. The imidazole ionic liquid was reacted with an equimolar amount of 1-methylimidazolium and a bromoalkane at 80°C for 12 h to obtain an intermediate; then, an equimolar amount of the intermediate was reacted with sulfuric acid (pKa1≈-3) at room temperature for 12 h, and the target ionic liquid was obtained after washing and purification with cyclohexane. The pyrrolidone ionic liquid was reacted with an equimolar amount of N-alkylpyrrolidone and a protic acid: sulfuric acid (pKa1≈-3), methanesulfonic acid (pKa=-1.9), p-toluenesulfonic acid (pKa=-2.8), formic acid (pKa=3.75), or acetic acid (pKa=4.76) at room temperature for 12 h, and the target ionic liquid was obtained after washing and purification with cyclohexane. The catalyst performance was evaluated using a continuous flow reactor according to the reaction conditions in Table 5 below, yielding the ester product n-butyl acetate. The n-butyl acetate product was detected by infrared spectroscopy, such as... Figure 5 As shown, the infrared spectrum is displayed at 770 cm⁻¹. -1 The vibration is a (CH2)n (n≥4) planar rocking vibration, 1037cm. -1 1245cm -1 For COC stretching vibration, 1366 cm -1 It is a -CH3 symmetrical bending vibration, 1739 cm.-1 This is the C=O stretching vibration of the ester group, 2875 cm⁻¹. -1 2964cm -1 The characteristic peaks are the stretching vibrations of -CH3 and -CH2-; these characteristic peaks indicate that n-butyl acetate was successfully synthesized.

[0043] Table 5 Summary of reactions in specific embodiments 403-491 Specific Implementation Number raw material Raw material molar ratio protic acid catalyst Catalyst to acid molar ratio (%) Reaction temperature (°C) Reaction time (h) Acid conversion rate (%) Product yield (%) 403 Acetic acid: n-Butanol 1：1.1 none p-Toluenesulfonic acid 0.2 120 4 82.2 75.8 404 Acetic acid: n-Butanol 1：1.1 methanesulfonic acid N-Ocylpyrrolidone Methylsulfonate 0.2 120 4 86.4 79.8 405 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 120 3 85.6 78.4 406 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 130 3 92.1 84.6 407 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 130 4 94.2 90.1 408 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 130 4 99.4 93.3 409 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.1 110 3 91.2 86.4 410 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 110 3 94.1 88.7 411 Acetic acid: n-Butanol 1：1.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.2 110 4 99.1 92.4 412 Acetic acid: n-Butanol 1：1.5 sulfuric acid 1-Methylimidazolium-3-butylhydrosulfate 0.3 110 4 100 96.5 413 Acetic acid: n-Butanol 1：1.3 Formic acid N-methylpyrrolidone formate 0.4 110 4 93.6 89.7 414 Acetic acid: n-Butanol 1：1.3 Formic acid N-methylpyrrolidone formate 0.3 110 4 90.9 87.1 415 Acetic acid: n-Butanol 1：1.1 Formic acid N-methylpyrrolidone formate 0.3 110 4 85.1 78.8 416 Acetic acid: n-Butanol 1：1.1 Formic acid N-methylpyrrolidone formate 0.2 110 4 82.2 77.4 417 Acetic acid: n-Butanol 1：1.5 Formic acid N-methylpyrrolidone formate 0.3 130 4 97.1 91.6 418 Acetic acid: n-Butanol 1：1.5 Formic acid N-methylpyrrolidone formate 0.4 110 4 96.2 91.1 419 Acetic acid: n-Butanol 1：1.5 Formic acid N-methylpyrrolidone formate 0.4 120 3 99.2 93.8 420 Acetic acid: n-Butanol 1：1.5 Formic acid N-methylpyrrolidone formate 0.3 120 4 99.8 96.7 421 Acetic acid: n-Butanol 1：1.1 Acetic acid N-Octypyrrolidone Acetate 0.2 120 3 81.2 76.3 422 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Octypyrrolidone Acetate 0.4 110 4 99.1 95.2 423 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Octypyrrolidone Acetate 0.4 120 4 99.5 96.2 424 Acetic acid: n-Butanol 1:1.3 Acetic acid N-Octypyrrolidone Acetate 0.4 120 4 97.1 93.1 425 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Octypyrrolidone Acetate 0.4 120 3 96.4 91.2 426 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Octypyrrolidone Acetate 0.4 110 4 93.2 90.1 427 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Octypyrrolidone Acetate 0.3 130 4 99.4 96.1 428 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Octypyrrolidone Acetate 0.4 130 4 100 98.2 429 Acetic acid: n-Butanol 1：1.3 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.2 120 3 94.4 93.3 430 Acetic acid: n-Butanol 1：1.5 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.3 130 4 100 95.7 431 Acetic acid: n-Butanol 1：1.5 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.3 120 3 99.4 92.3 432 Acetic acid: n-Butanol 1：1.5 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.3 110 4 93.7 88.4 433 Acetic acid: n-Butanol 1：1.1 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.4 130 4 90.4 86.5 434 Acetic acid: n-Butanol 1：1.1 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.3 120 4 84.6 78.2 435 Acetic acid: n-Butanol 1：1.5 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.3 120 4 99.8 95.6 436 Acetic acid: n-Butanol 1：1.5 sulfuric acid N-ethylpyrrolidone hydrogen sulfate 0.4 120 3 97.9 93.8 437 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.1 120 4 82.4 75.6 438 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.3 120 4 93.3 88.4 439 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.3 120 4 99.4 92.7 440 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.4 130 4 100 96.7 441 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.4 110 4 84.3 77.6 442 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.2 120 4 86.1 77.1 443 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.4 130 3 91.6 86.6 444 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-cyclohexylpyrrolidone p-toluenesulfonic acid 0.3 130 3 88.9 84.2 445 Acetic acid: n-Butanol 1：1.3 Formic acid N-vinylpyrrolidone formate 0.3 130 3 94.1 90.1 446 Acetic acid: n-Butanol 1：1.3 Formic acid N-vinylpyrrolidone formate 0.4 130 3 96.1 91.3 447 Acetic acid: n-Butanol 1：1.5 Formic acid N-vinylpyrrolidone formate 0.3 130 3 99.1 93.2 448 Acetic acid: n-Butanol 1：1.1 Formic acid N-vinylpyrrolidone formate 0.2 120 4 86.4 81.1 449 Acetic acid: n-Butanol 1：1.5 Formic acid N-vinylpyrrolidone formate 0.4 120 4 99.6 95.3 450 Acetic acid: n-Butanol 1：1.3 Formic acid N-vinylpyrrolidone formate 0.2 120 4 91.1 86.2 451 Acetic acid: n-Butanol 1：1.3 Formic acid N-vinylpyrrolidone formate 0.3 130 4 88.1 83.1 452 Acetic acid: n-Butanol 1：1.5 Formic acid N-vinylpyrrolidone formate 0.4 130 4 100 96.8 453 Acetic acid: n-Butanol 1：1.1 Acetic acid N-Cyclohexylpyrrolidone acetate 0.3 110 4 85.5 80.1 454 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.4 120 4 92.1 84.4 455 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.3 120 3 89.4 83.2 456 Acetic acid: n-Butanol 1：1.5 Acetic acid N-Cyclohexylpyrrolidone acetate 0.3 110 4 91.1 86.8 457 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.4 130 4 96.6 92.4 458 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.3 120 4 95.4 91.4 459 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.2 110 3 90.3 84.3 460 Acetic acid: n-Butanol 1：1.3 Acetic acid N-Cyclohexylpyrrolidone acetate 0.4 130 4 95.5 93.4 461 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.4 130 4 99.8 96.4 462 Acetic acid: n-Butanol 1：1.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 110 4 93.4 89.1 463 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.4 110 4 93.8 90.1 464 Acetic acid: n-Butanol 1：1.5 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 130 4 100 97.4 465 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.4 120 4 95.8 92.2 466 Acetic acid: n-Butanol 1：1.3 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 130 4 99.7 94.1 467 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.3 130 4 94.4 91.1 468 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 120 4 87.4 82.8 469 Acetic acid: n-Butanol 1：1.1 sulfuric acid 1-Methylimidazolium hydrogen sulfate 0.2 120 3 84.8 80.2 470 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.4 110 3 84.8 81.1 471 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.4 120 3 89.8 83.1 472 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.4 130 3 92.2 85.1 473 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 130 4 93.3 87.2 474 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 110 3 94.1 90.3 475 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 130 4 100 95.4 476 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.2 130 4 91.2 85.4 477 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.3 130 4 94.2 88.8 478 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-Dodecylpyrrolidone p-Toluenesulfonic Acid 0.4 130 4 99.2 92.4 479 Acetic acid: n-Butanol 1：1.5 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.4 110 4 96.8 92.2 480 Acetic acid: n-Butanol 1：1.5 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.3 110 3 94.4 90.1 481 Acetic acid: n-Butanol 1：1.5 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.3 120 3 96.4 92.7 482 Acetic acid: n-Butanol 1：1.3 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.2 120 4 89.7 84.4 483 Acetic acid: n-Butanol 1：1.3 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.2 130 4 91.1 86.6 484 Acetic acid: n-Butanol 1：1.5 methanesulfonic acid N-ethylpyrrolidone methanesulfonic acid 0.4 130 4 100 96.7 485 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.2 110 4 81.2 76.4 486 Acetic acid: n-Butanol 1：1.1 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.3 110 4 85.5 78.7 487 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.4 130 4 95.4 91.2 488 Acetic acid: n-Butanol 1：1.3 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.3 120 3 90.9 87.9 489 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.4 130 3 97.4 93.5 490 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.3 130 4 100 96.2 491 Acetic acid: n-Butanol 1：1.5 p-Toluenesulfonic acid N-ethylpyrrolidone p-toluenesulfonic acid 0.2 130 4 99.3 94.8 As shown in Table 5, in Specific Example 403, using a conventional reactor and catalyst, the conversion rate of p-toluenesulfonic acid was 82.2%, and the product yield was 75.8%, both relatively low. In Specific Example 69, although a conventional reactor was still used, an ionic liquid catalyst, N-octylpyrrolidone methanesulfonate, was employed, increasing the acid conversion rate to 86.4% and the product yield to 79.8%, showing some improvement. In Specific Examples 405-491, different types of pyrrolidone and imidazole ionic liquids were used as catalysts, and a continuous flow reactor was employed. Under general reaction conditions, the acid conversion rate was above 86%, and the product yield was significantly improved, reaching a maximum of 98.2%. Particularly in Specific Examples 422-428 and 429-431, the catalyst type and dosage were further optimized, resulting in acid conversion rates exceeding 93% and stable product yields at a high level, reaching a maximum of 98.2%. These data fully demonstrate that the ionic liquid catalyst coupled with the continuous flow reactor also exhibits high efficiency and superiority in the preparation of the industrial solvent n-butyl acetate.

[0044] In summary, ester products including dioctyl terephthalate, dioctyl phthalate, ethyl butyrate, dimethyl terephthalate, and n-butyl acetate were prepared using the specific examples 1-491 described above. These ester products were efficiently generated under the coupled effect of an ionic liquid catalyst and a continuous flow reactor. Experimental results show that different raw material ratios, catalyst types and amounts, reaction temperatures, and reaction times significantly affect acid conversion and product yield. Optimizing these reaction conditions can significantly improve the yield of the target ester products. For example, in the preparation of dioctyl terephthalate, using N-vinylpyrrolidone hydrogen sulfate as a catalyst and reacting at 180°C for 4 hours resulted in 100% acid conversion and a product yield as high as 97.4%. Similarly, in the preparation of n-butyl acetate, high conversion and high yield were also achieved by adjusting the molar ratio of catalyst to acid and the reaction temperature. These results provide important reference data for industrial production and demonstrate the broad application prospects of ionic liquids in ester synthesis.

[0045] Further analysis revealed that the choice of ionic liquid catalyst plays a decisive role in the reaction effect. Imidazole and pyrrolidone ionic liquids, due to their unique structure and properties, exhibit excellent catalytic activity and selectivity in esterification reactions. Compared with traditional catalysts, ionic liquid catalysts have advantages such as low volatility, high thermal stability, and reusability, significantly reducing production costs and environmental pollution. Simultaneously, the application of continuous flow reactors makes the reaction process more continuous and stable, improving production efficiency and product quality. In actual production, reaction conditions can be flexibly adjusted according to different raw materials and target products, and suitable ionic liquid catalysts can be selected to achieve efficient and green synthesis of ester products. With the continuous development of research, the application of ionic liquid coupled continuous flow catalysis technology in the field of ester synthesis will become more widespread, and it is expected to promote the sustainable development of related industries.

[0046] For those skilled in the art, the specific embodiments are merely illustrative descriptions of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution, such as changing the mass of a substance or a reaction parameter, or directly applying the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for preparing ester products based on an ionic liquid catalyst coupled with a continuous reactor, characterized in that, The use of ionic liquid catalysts coupled with continuous flow reaction technology specifically includes the following steps: S1: Mix the acid and alcohol used to prepare ester products according to the specified ratio, and then add an ionic liquid catalyst to obtain a mixture; S2: Add the mixture prepared in step S1 into a continuous flow reactor. At a reaction temperature of 25~240℃, the mixture is uniformly mixed and reacted in the continuous flow reactor. After the reaction is completed, the ester product is obtained.

2. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 1, characterized in that, The ionic liquid catalyst includes pyrrolidone-based ionic liquids and / or imidazole-based ionic liquids.

3. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 2, characterized in that, The preparation steps of pyrrolidone ionic liquids are as follows: equimolar amounts of N-alkylpyrrolidone are reacted with a protic acid at room temperature for 6-16 hours, and the pyrrolidone ionic liquid is obtained after purification.

4. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 3, characterized in that, The preparation steps of imidazole ionic liquids are as follows: equimolar amounts of imidazole substances are reacted with bromoalkane at 40-110℃ for 4-12 hours to obtain an intermediate. The intermediate is then reacted with an equimolar amount of protic acid at room temperature for 6-16 hours. After purification, imidazole ionic liquids are synthesized.

5. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 4, characterized in that, In the preparation of pyrrolidone-based ionic liquids and imidazole-based ionic liquids, the protic acid is one of concentrated sulfuric acid, phosphoric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, formic acid, acetic acid, propionic acid, and butyric acid; the solvent used for purification is one of ethyl acetate, cyclohexane, anhydrous methanol, anhydrous diethyl ether, and toluene.

6. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 4, characterized in that, In the preparation of imidazole ionic liquids, the bromoalkane is one of bromoethane, bromobutane, and bromohexane.

7. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 4, characterized in that, The acid in step S1 is one of phthalic acid, terephthalic acid, sebacic acid, azelaic acid, acetic acid, and butyric acid; the alcohol is one of methanol, ethanol, n-butanol, n-octanol, and isooctanol.

8. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 7, characterized in that, In step S1, the molar ratio of alcohol to acid is (1~8):

1.

9. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 8, characterized in that, The amount of ionic liquid catalyst used in step S1 is 0.01% to 10% of the amount of acid.

10. The method for preparing ester products based on an ionic liquid catalyst coupled to a continuous reactor according to claim 8, characterized in that, The ester products in step S2 include one of the following: plasticizer esters, polymer monomer esters, industrial solvents, and food flavorings.

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