Preparation method and preparation system of cyano olefine acid ester

Abstract

The invention discloses a preparation method and a preparation system of cyano olefine acid ester, and relates to the technical field of preparation of cyano olefine acid ester. The preparation method of the cyanoacrylate comprises the following steps: mixing cyanoacetate, a carbonyl compound, a first catalyst and a second catalyst in a container for condensation reaction to prepare the cyanoacrylate, rectifying the substances in the container to obtain a mixture containing the first catalyst and water; and separating the mixture containing the first catalyst and water to obtain the first catalyst, and introducing the first catalyst into the container. According to the technical scheme, in the reaction process, the byproduct water is continuously separated out, the first catalyst is recycled, and the recycled first catalyst is introduced into the container to continue to participate in the reaction, so that forward proceeding of a reaction system is promoted, the conversion rate and the yield of the reaction are improved, the reaction time is shortened, and the impurity content is reduced; the method can be used for solving the problems of low conversion rate, low yield and high impurity content in preparation of cyanoolefine acid ester.

Description

Technical Field

[0001] The invention relates to the technical field of cyanoacrylate preparation, and in particular to a cyanoacrylate preparation method and a preparation system thereof. Background Art

[0002] In recent years, the supply of ultraviolet absorbers for preventing mid-band ultraviolet rays has been in short supply, and people are in urgent need of seeking a safe and excellent ultraviolet absorber to prevent the adverse effects of ultraviolet rays. Cyanoacrylate ultraviolet absorbers are an important class of ultraviolet absorbers, which are widely used in various sunscreen products, especially high-end sunscreen products. There are many commercial products, such as 2-cyano-3,3-diphenylacrylate isooctyl ester (UV-3039, trade name: octocrylene), 2-cyano-3,3-diphenylacrylate pentaerythritol ester (UV-3030) and 2-cyano-3,3-diphenylacrylate ethyl ester (UV-3035, trade name: etocrylene).

[0003] At present, the conventional synthesis method of cyanoacrylate is to condense cyanoacetate with a suitable carbonyl compound in a catalyst system. Although the above method has simple steps, its conversion rate and yield still have room for further improvement. In the production process of this reaction, since the byproduct water cannot be removed from the reaction system in time, it will greatly inhibit the continued reaction, resulting in a low single batch conversion rate of cyanoacrylate products; and the retention of byproduct water will also cause the increase of amide impurities, which is not easy to separate, causing product turbidity. At present, the conversion rate of the reaction is mainly increased by adding organic solvents such as toluene or heptane to carry water, but the product quality obtained by this preparation method is not high, and its amide impurity content is still very high, and the use of a large amount of organic solvents is not conducive to environmental protection.

[0004] Therefore, the current preparation of cyanoacrylate products still has the problems of low conversion rate, low yield and high impurity content. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing cyanoacrylate and a preparation system thereof, aiming to solve the problems of low conversion rate, low yield and high impurity content in the prior art for preparing cyanoacrylate.

[0006] To achieve the above object, the present invention provides a method for preparing cyanoacrylate, comprising the following steps:

[0007] Mixing cyanoacetate, a carbonyl compound, a first catalyst and a second catalyst in a container to carry out a condensation reaction to prepare cyanoacrylate; the first catalyst includes a fatty acid with a carbon number of C2-C4, and the second catalyst includes an ammonium monoacid with a carbon number of C2-C7;

[0008] distilling the material in the container to obtain a mixture containing the first catalyst and water;

[0009] The mixture containing the first catalyst and water is separated to obtain the first catalyst, and the first catalyst is introduced into the container.

[0010] In one embodiment, the temperature for the condensation reaction is 60°C to 120°C; and / or,

[0011] The condensation reaction time is 4 to 15 hours.

[0012] In one embodiment, the molar ratio of the cyanoacetate to the carbonyl compound is (0.7-3):1, preferably, the molar ratio is (0.7-2):1.

[0013] In one embodiment, the molar ratio of the cyanoacetate, the monobasic ammonium acid and the monocarboxylic acid is (0.7-3.0):(0.15-1.5):(0.45-3).

[0014] In one embodiment, the first catalyst includes any one of acetic acid, propionic acid and butyric acid, and the second catalyst includes any one of ammonium acetate, ammonium propionate and ammonium butyrate.

[0015] In one embodiment, the cyanoacetate includes any one of isooctyl cyanoacetate, methyl cyanoacetate, ethyl cyanoacetate and propyl cyanoacetate.

[0016] In one embodiment, the carbonyl compound includes any one of benzophenone, a benzophenone derivative and acetophenone.

[0017] In one embodiment, before the step of mixing the cyanoacetic acid ester, the carbonyl compound, the first catalyst and the second catalyst in a container to perform a condensation reaction to prepare the cyanoacrylate ester, the step includes:

[0018] Dehydrating cyanoacetic acid under vacuum at 75-90° C. for 1-2 hours, mixing the dehydrated cyanoacetic acid, alkyl alcohol and concentrated sulfuric acid as a catalyst, and performing an esterification reaction at 100-120° C. for 2-6 hours to obtain cyanoacetic acid ester;

[0019] Wherein, the cyanoacetic acid is a 75% to 85% cyanoacetic acid aqueous solution;

[0020] The molar ratio of cyanoacetic acid to alkyl alcohol is (0.8-1.5):1;

[0021] The mass ratio of the cyanoacetic acid to the concentrated sulfuric acid is 1:(0.02-0.1).

[0022] The present invention provides a preparation system for implementing the cyanoacrylate preparation method described in the above technical solution, wherein the preparation system comprises a reaction unit, a distillation unit, a separation and recovery unit connected in sequence by pipelines.

[0023] unit,

[0024] Wherein, the separation and recovery unit is connected to the reaction unit through a pipeline, and the reaction unit includes a container;

[0025] The cyanoacetate, the carbonyl compound, the first catalyst and the second catalyst react through the reaction unit;

[0026] The distillation unit is used to distill the substances in the reaction unit to obtain the first catalyst, the second catalyst and water, and the second catalyst is returned to the reaction unit through the distillation unit;

[0027] The separation and recovery unit is used to separate the first catalyst from water and introduce the first catalyst into the reaction unit.

[0028] In one embodiment, the distillation unit comprises a distillation tower, and the distillation tower is connected to the container via a pipeline.

[0029] In one embodiment, the separation and recovery unit comprises a condenser, a mixed solvent storage tank, a membrane dehydration device and a water recovery storage tank which are connected in sequence by pipelines.

[0030] Wherein, the condenser is connected to the distillation tower through a pipeline, and the membrane dehydration device is connected to the reaction unit through a pipeline.

[0031] The technical solution of the present invention continuously separates the byproduct water and recovers the first catalyst, and passes the recovered first catalyst into the container to continue to participate in the reaction, thereby promoting the reaction system to proceed in the forward direction, greatly improving the conversion rate and yield of the reaction, shortening the reaction time, and improving production stability. In addition, conventional monobasic ammonium acid and short-chain fatty acids are selected as the catalytic system, which can reduce the generation and enrichment of impurities, reduce the impurity content, improve product quality, and do not need to modify the catalyst. The preparation of cyanoacrylate by the technical solution of the present invention has the characteristics of high conversion rate, high yield and low impurity content, avoids complex catalyst modification and post-treatment processes, reduces the generation of mixed acid wastewater, is conducive to mass production, and can be used to solve the problems of low conversion rate, low yield and high impurity content in the preparation of cyanoacrylate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0033] Figure 1 is a schematic diagram of an embodiment of a preparation system for preparing cyanoacrylate according to the present invention;

[0034] Figure 2 This is a schematic diagram of a system for preparing cyanoacrylate according to Example 9 of the present invention;

[0035] Figure 3 This is a schematic diagram of a preparation system for preparing cyanoacrylate according to Comparative Example 4 of the present invention.

[0036] Description of Figure Numbers:

[0037] 1. Reaction unit; 11. Container; 2. Distillation unit; 21. Distillation tower; 3. Separation and recovery unit; 31. Condenser; 32. Mixed solvent storage tank; 33. Membrane dehydration device; 34. Water recovery tank.

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] At present, the conventional synthesis method of cyanoacrylate is to use cyanoacetic acid ester and suitable carbonyl compound to carry out knoevenagel condensation reaction in catalyst system. Although the above method has simple steps, its conversion rate and yield still have room for further improvement. In the production process of this reaction, since the byproduct water cannot be removed from the reaction system in time, it will greatly inhibit the continuous progress of the reaction, resulting in low conversion rate of single batch of cyanoacrylate products; and the retention of byproduct water will also cause the increase of amide impurities, which is not easy to separate, causing turbidity of the product. At present, the conversion rate of the reaction is mainly increased by adding organic solvents such as toluene or heptane to carry water, but the product quality obtained by this preparation method is not high, the amide impurity content is still very high, and the use of a large amount of organic solvents is not conducive to environmental protection.

[0043] In view of this, the present invention provides a method for preparing cyanoacrylate, comprising the following steps:

[0044] Mixing cyanoacetate, a carbonyl compound, a first catalyst and a second catalyst in a container to carry out a condensation reaction to prepare cyanoacrylate; the first catalyst includes a fatty acid with a carbon number of C2-C4, and the second catalyst includes an ammonium monoacid with a carbon number of C2-C7;

[0045] distilling the material in the container to obtain a mixture containing the first catalyst and water;

[0046] The mixture containing the first catalyst and water is separated to obtain the first catalyst, and the first catalyst is introduced into the container.

[0047] Cyanoacetic acid ester and carbonyl compound are subjected to knoevenagel condensation reaction under a catalytic system to generate cyanoacrylate and byproduct water. The technical solution of the present invention is to continuously separate the byproduct water and recover the first catalyst during the reaction process, and pass the recovered first catalyst into a container to continue to participate in the reaction, thereby achieving the goal of improving the yield and reducing the impurity content. After the reaction starts, the material in the container is rectified. After the rectification, the second catalyst is first returned to the container to continue the reaction due to its weak volatility, while the byproduct water and the first catalyst are volatilized and converted into a mixture containing the first catalyst and water. After the mixture containing the first catalyst and water is dehydrated, water is separated from the reaction system and the first catalyst is obtained. The recovered first catalyst is passed into the container through a pipeline to continue to participate in the reaction. The steps of returning the second catalyst to the container, separating water from the reaction system, and returning the first catalyst to the container are circulated until the reaction ends.

[0048] Since the byproduct water is continuously separated and the first catalyst is recovered during the reaction, and the recovered first catalyst is passed into the container to continue to participate in the reaction, the technical solution of the present invention can promote the reaction system to proceed in the forward direction, greatly improve the yield of the reaction, shorten the reaction time, and improve production stability. In addition, the technical solution of the present invention selects ammonium monoacid and short-chain fatty acids as the catalytic system, which can reduce the generation and enrichment of impurities, reduce the impurity content, and improve product quality. Ammonium monoacid and short-chain fatty acids are conventional catalyst systems, so the technical solution of the present invention does not need to modify the catalytic system, avoiding a complicated catalyst modification process.

[0049] It should be noted that the cyanoacetic acid ester can be directly purchased or prepared by oneself. In this embodiment, the method of preparing by oneself includes the following steps:

[0050] Dehydrating cyanoacetic acid under vacuum at 75-90° C. for 1-2 hours, mixing the dehydrated cyanoacetic acid, alkyl alcohol and concentrated sulfuric acid as a catalyst, and performing an esterification reaction at 100-120° C. for 2-6 hours to obtain cyanoacetic acid ester;

[0051] Wherein, the cyanoacetic acid is a 75% to 85% cyanoacetic acid aqueous solution;

[0052] The molar ratio of cyanoacetic acid to alkyl alcohol is (0.8-1.5):1;

[0053] The mass ratio of the cyanoacetic acid to the concentrated sulfuric acid is 1:(0.02-0.1).

[0054] Using 75% to 85% cyanoacetic acid aqueous solution is beneficial to reducing production costs. Distilling the crude cyanoacetic acid is beneficial to obtaining cyanoacetic acid ester with a purity greater than 99%.

[0055] In one embodiment of the present invention, the alkyl alcohol is isooctyl alcohol, the molar ratio of the cyanoacetic acid to the isooctyl alcohol is 0.84:1, and the mass ratio of the cyanoacetic acid to the concentrated sulfuric acid is 1:0035.

[0056] In the embodiment of the present invention, the temperature for the condensation reaction is 60° C. to 120° C. If the reaction temperature is too low, the reaction rate will be slow, and if the reaction temperature is too high, too many impurities will be generated.

[0057] In an embodiment of the present invention, the condensation reaction time is 4 to 15 hours. Setting the reaction time within the above range is conducive to sufficient reaction, reducing the generation of by-products and controlling production costs.

[0058] In an embodiment of the present invention, the molar ratio of the cyanoacetic acid ester to the carbonyl compound for condensation reaction is (0.7-3):1. When the molar ratio of the cyanoacetic acid ester to the carbonyl compound is within the above range, it is beneficial to improve the conversion rate. If it is too low or too high, it will cause an excess of one of the raw materials, increase the difficulty of purification and production cost. Preferably, the molar ratio of the cyanoacetic acid ester to the carbonyl compound is set to (0.7-2):1.

[0059] In an embodiment of the present invention, the molar ratio of the cyanoacetate, the monobasic ammonium acid and the monocarboxylic acid is (0.7-3): (0.15-1.5): (0.45-3). When the molar ratio of the cyanoacetate, the monobasic ammonium acid and the monocarboxylic acid is within the above range, it is beneficial to improve the reaction conversion rate. If it is lower than the range, the reaction conversion rate will be low. If it is higher than the range, the production cost and the difficulty of purification will be increased.

[0060] In an embodiment of the present invention, the first catalyst includes any one of acetic acid, propionic acid and butyric acid, and the second catalyst includes any one of ammonium acetate, ammonium propionate and ammonium butyrate. Different catalyst systems are selected according to different reaction substrates.

[0061] In an embodiment of the present invention, the cyanoacetate includes any one of isooctyl cyanoacetate, methyl cyanoacetate, ethyl cyanoacetate and propyl cyanoacetate.

[0062] In an embodiment of the present invention, the carbonyl compound includes any one of benzophenone, a benzophenone derivative and acetophenone.

[0063] The present invention provides a manufacturing system for implementing the cyanoacrylate preparation method described in the above technical solution.

[0064] See also Figure 1 and Figure 2 The preparation system comprises a reaction unit 1, a distillation unit 2, and a separation and recovery unit 3 which are connected in sequence through pipelines.

[0065] The separation and recovery unit 3 is connected to the reaction unit 1 through a pipeline, and the reaction unit 1 includes a container 11;

[0066] The cyanoacetate, the carbonyl compound, the first catalyst and the second catalyst react through the reaction unit 1;

[0067] The distillation unit 2 is used to distill the material in the reaction unit 1 to obtain the first catalyst, the second catalyst and water, and the second catalyst is returned to the reaction unit through the distillation unit;

[0068] The separation and recovery unit 3 is used to separate the first catalyst from water and introduce the first catalyst into the reaction unit 1 .

[0069] The technical solution of the present invention provides a manufacturing system for cyanoacrylate, and the preparation system includes a reaction unit 1, a distillation unit 2, and a separation and recovery unit 3 which are sequentially connected by pipelines. When the manufacturing system is used, while the reaction unit 1 is performing a dehydration reaction, the distillation unit 2 can distill the components volatilized from the reaction unit 1 and pass them into the separation and recovery unit 3, and the byproduct water is continuously removed from the reaction system through the separation and recovery unit 3, and the first catalyst and the second catalyst can be re-introduced into the reaction unit 1 to continue the reaction, thereby promoting the forward progress of the reaction system, greatly improving the conversion rate of the reaction, shortening the reaction time, improving the production stability, making the entire production process more stable and controllable, and facilitating the maintenance of consistent product quality and output during long-term operation.

[0070] In an embodiment of the present invention, the distillation unit 2 includes a distillation tower 21, and the distillation tower 21 is connected to the container 11 through a pipeline.

[0071] In an embodiment of the present invention, the separation and recovery unit 3 comprises a condenser 31, a mixed solvent storage tank 32, a membrane dehydration device 33 and a water recovery storage tank 34 which are connected in sequence through pipelines.

[0072] The condenser 31 is connected to the distillation tower 21 through a pipeline, and the membrane dehydration device 33 is connected to the reaction unit 1 through a pipeline. The membrane dehydration device 33 is connected to the container 11 in the reaction unit 1 through a pipeline.

[0073] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0074] Example 1

[0075] A method for preparing a cyanoacrylate comprises the following steps:

[0076] (1) 100 g of isooctyl cyanoacetate (0.507 mol), 132 g of benzophenone (0.724 mol), 30 g of ammonium acetate (0.390 mol) and 42.6 g of acetic acid (0.710 mol) were mixed in a container to carry out a condensation reaction, and the reaction was carried out at 90° C. under vacuum conditions for 15 h to obtain isooctyl 2-cyano-3,3-diphenylacrylate;

[0077] (2) heating the 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (1) at 80° C. to evaporate acetic acid, then adding 10% water to wash three times to remove ammonium acetate, and purifying the product by molecular distillation to obtain the 2-cyano-3,3-diphenylacrylate isooctyl ester product;

[0078] In the process of performing step (1), the material in the container of step (1) is distilled to obtain a mixture containing acetic acid and water, and then the mixture containing acetic acid and water is dehydrated to obtain acetic acid, and the acetic acid is introduced into the container of step (1) to continue the reaction.

[0079] Example 2

[0080] A method for preparing a cyanoacrylate comprises the following steps:

[0081] (1) 100 g of cyanoacetic acid (1.249 mol) and 194 g of isooctyl alcohol (1.490 mol) were mixed, vacuum dehydrated at 80° C. for 2 h, 3.5 g of concentrated sulfuric acid was added to the dehydrated cyanoacetic acid, mixed, reacted at 100° C. for 4 h, first washed with water, and then purified by distillation to obtain isooctyl cyanoacetate;

[0082] (2) 100 g of isooctyl cyanoacetate (0.507 mol), 77 g of benzophenone (0.422 mol), 43 g of ammonium acetate (0.558 mol) and 60.8 g of acetic acid (1.012 mol) were mixed in a container to carry out a condensation reaction, and the reaction was carried out at 90° C. under vacuum conditions for 15 h to obtain isooctyl 2-cyano-3,3-diphenylacrylate;

[0083] (3) heating the 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (2) at 80° C. to evaporate acetic acid, then adding 10% water to wash three times to remove ammonium acetate, and purifying by molecular distillation to obtain a 2-cyano-3,3-diphenylacrylate isooctyl ester product after refining;

[0084] In the process of performing step (2), the material in the container of step (2) is distilled to obtain a mixture containing acetic acid and water, and then the mixture containing acetic acid and water is dehydrated to obtain acetic acid, and the acetic acid is introduced into the container of step (2) to continue the reaction.

[0085] Example 3

[0086] Compared with Example 2, the difference is that the molar ratio of isooctyl cyanoacetate to benzophenone is 1.2:1; the molar ratio of isooctyl cyanoacetate, acetic acid and ammonium acetate is 1.2:1:0.5; and the reaction is carried out at 100° C. under vacuum conditions for 13 hours.

[0087] Example 4

[0088] Compared with Example 2, the difference is that the molar ratio of isooctyl cyanoacetate to benzophenone is 2:1; the molar ratio of isooctyl cyanoacetate, acetic acid and ammonium acetate is 2:3:1.5; and the reaction is carried out at 120° C. under vacuum conditions for 4 hours.

[0089] Example 5

[0090] Compared with Example 2, the difference is that acetic acid is replaced by propionic acid; and the reaction is carried out at 60° C. under vacuum conditions for 15 hours.

[0091] Example 6

[0092] Compared with Example 2, the difference is that acetic acid is replaced by propionic acid, and ammonium acetate is replaced by ammonium propionate.

[0093] Example 7

[0094] Compared with Example 2, the difference is that isooctyl cyanoacetate is replaced by ethyl cyanoacetate; and the purification method is also different. The specific operation of step (3) is: the 2-cyano-3,3-diphenylacrylate obtained in step (2) is heated at 80° C. to evaporate the acetic acid, then 10% water is added to wash three times to remove the ammonium acetate, and 1.2 equivalents of ethanol are added to crystallize to obtain purified 2-cyano-3,3-diphenylacrylate.

[0095] Example 8

[0096] Compared with Example 2, the difference is that benzophenone is replaced by cyanoacetophenone, and the cyanoacrylate product finally obtained is 2-cyano-3-methyl-3-phenylacrylate isooctyl ester.

[0097] Example 9

[0098] A system for preparing the cyanoacrylates of Examples 1-8, such as Figure 2 As shown, the preparation system includes a container 11, a distillation tower 21, a condenser 31, a mixed solvent storage tank 32, a membrane dehydration device 33 and a water recovery storage tank 34 which are sequentially connected by pipelines, and the membrane dehydration device 33 is connected to the container 11 by a pipeline.

[0099] Comparative Example 1

[0100] Compared with Example 2, the difference is that during the execution of step (2), only the material in the container of step (2) is distilled to obtain a mixture containing acetic acid and water, but the steps of recovering acetic acid and adding the recovered acetic acid into the container for further reaction are not performed; the molar ratio of cyanoacetate, acetic acid and ammonium acetate is 1.2:6:1.1.

[0101] Comparative Example 2

[0102] Compared with Example 1, the difference is that acetic acid is not contained, and the specific steps are as follows:

[0103] (1) Mix 100 g of isooctyl cyanoacetate, 132 g of benzophenone and 30 g of ammonium acetate in a container, and carry out a condensation reaction at 90° C. under vacuum conditions for 15 h to obtain isooctyl 2-cyano-3,3-diphenylacrylate;

[0104] (2) heating the 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (1) at 80° C. to evaporate acetic acid, then adding 10% water to wash three times to remove ammonium acetate, and purifying by molecular distillation to obtain a purified 2-cyano-3,3-diphenylacrylate isooctyl ester product;

[0105] Wherein, during the execution of step (1), the material in the container of step (1) is simultaneously distilled.

[0106] Comparative Example 3

[0107] Compared with Example 1, the difference is that ammonium acetate is not contained, and the specific steps are as follows:

[0108] (1) Mixing 100 g of isooctyl cyanoacetate, 132 g of benzophenone and 42.6 g of acetic acid in a container, and carrying out a condensation reaction at 90° C. under vacuum conditions for 15 h to obtain a mixture containing isooctyl 2-cyano-3,3-diphenylacrylate;

[0109] (2) heating the 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (1) at 80° C. to evaporate acetic acid, then adding 10% water to wash three times to remove ammonium acetate, and purifying by molecular distillation to obtain a purified 2-cyano-3,3-diphenylacrylate isooctyl ester product;

[0110] In the process of performing step (1), the material in the container of step (1) is distilled to obtain a mixture containing acetic acid and water, and then the mixture containing acetic acid and water is dehydrated to obtain acetic acid, and the acetic acid is introduced into the container of step (1) to continue the reaction.

[0111] Comparative Example 4

[0112] Conventional preparation systems for preparing cyanoacrylates, such as Figure 3As shown, the preparation system includes a reactor, a condenser and a mixed solvent storage tank which are connected in sequence through pipelines; the preparation system also includes a fatty acid storage tank, which is connected to the reactor to add fatty acids to the reactor; the mixed solvent storage tank is used to store by-product water and fatty acids.

[0113] Performance Testing

[0114] The conversion rate, yield, reaction time and purity of the cyanoacrylates obtained in Examples 1-8 and Comparative Examples 1-3 were tested. The test results are shown in Table 1.

[0115] The preparation systems of Example 9 and Comparative Example 4 were used to prepare 2-cyano-3,3-diphenylacrylate isooctyl ester, and the conversion rate, yield and purity of the prepared 2-cyano-3,3-diphenylacrylate are tested. The test results are shown in Table 1.

[0116] The operating steps for preparing cyanoacrylate using the preparation system of Example 9 are as follows:

[0117] (1) Add 100 g of isooctyl cyanoacetate, 132 g of benzophenone, 30 g of ammonium acetate and 42.6 g of acetic acid into a container, and react at 90° C. for 15 h to obtain isooctyl 2-cyano-3,3-diphenylacrylate;

[0118] (2) The 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (1) is heated at 80° C. to evaporate acetic acid, then 10% water is added to wash three times to remove ammonium acetate, and purified by molecular distillation to obtain a purified 2-cyano-3,3-diphenylacrylate isooctyl ester product.

[0119] The operating steps for preparing cyanoacrylate using the preparation system of Comparative Example 4 are as follows:

[0120] (1) Add 100 g of isooctyl cyanoacetate, 132 g of benzophenone, 30 g of ammonium acetate and 42.6 g of acetic acid into a reaction kettle, and react at 90° C. for 15 h to obtain isooctyl 2-cyano-3,3-diphenylacrylate; during the reaction, add 127.8 g of acetic acid;

[0121] (2) The 2-cyano-3,3-diphenylacrylate isooctyl ester obtained in step (1) is heated at 80° C. to evaporate acetic acid, then 10% water is added to wash three times to remove ammonium acetate, and purified by molecular distillation to obtain a purified 2-cyano-3,3-diphenylacrylate isooctyl ester product.

[0122] The test methods for conversion rate, yield, reaction time and purity are as follows:

[0123] Conversion rate: Based on the converted carbonyl compounds, the conversion rate is calculated as:

[0124]

[0125] Where:

[0126] R1——peak area of ​​carbonyl compounds in sample solution;

[0127] R2——product peak area of ​​sample solution;

[0128] K1 – the slope of the standard curve of carbonyl compounds and target products.

[0129] Yield: The calculation formula is:

[0130]

[0131] Where:

[0132] M1 – the actual quality of the final product;

[0133] m1——molecular weight of the final product;

[0134] M2——the mass of raw materials with a smaller proportion;

[0135] m2——molecular weight of the smaller proportion of raw materials.

[0136] Reaction rate: measured by the time to reach 70% conversion.

[0137] Purity: The purity of the products obtained in Examples 1-6 was measured by high performance liquid chromatography to be between 99.0% and 99.7%.

[0138] Table 1 Parameters and performance test results of Examples 1 to 9 and Comparative Examples 1 to 4

[0139]

[0140]

[0141] In Table 1, “-” means that the substance is not contained, and “ / ” means that the item is not carried out.

[0142] As can be seen from Table 1 and the above content, the purity of the cyanoacrylate prepared by the preparation method of Examples 1-6 is high, which can reach 99%. The test data of the conversion rate, yield, and reaction rate of the cyanoacrylate prepared by the preparation method of Examples 1-6 are also better than those of Comparative Examples 1-3, indicating that the technical scheme of the present invention is conducive to improving the conversion rate and yield of the reaction and greatly shortening the reaction time. Among them, the preparation method of Comparative Example 1 does not recover the catalyst acetic acid, and the removal effect of water in the reaction system is also poor. Even if the amount of catalyst acetic acid used is increased, the test results of the conversion rate and yield of the reaction are also poor; the preparation methods of Comparative Examples 2 and 3 use only a single catalyst, so the catalytic effect is poor, and the conversion rate and yield of the reaction are low. It can also be seen from the above content that the conversion rate and yield of the cyanoacetic acid ester prepared by the preparation system of Example 9 are better than those of Comparative Example 4, indicating that the use of the preparation system provided by the present invention can improve the conversion rate and yield of the cyanoacrylate product.

[0143] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a cyanoacrylate, characterized in that: The following steps are involved: Mixing cyanoacetate, a carbonyl compound, a first catalyst and a second catalyst in a container to carry out a condensation reaction to prepare cyanoacrylate; the first catalyst includes a fatty acid with a carbon number of C2-C4, and the second catalyst includes an ammonium monoacid with a carbon number of C2-C7; distilling the material in the container to obtain a mixture containing the first catalyst and water; The mixture containing the first catalyst and water is separated to obtain the first catalyst, and the first catalyst is introduced into the container.

2. The method for preparing cyanoacrylate according to claim 1, wherein The temperature for the condensation reaction is 60°C to 120°C; and / or, The condensation reaction time is 4 to 15 hours.

3. The method for preparing cyanoacrylate according to claim 1, wherein The molar ratio of the cyanoacetate to the carbonyl compound is (0.7-3):1, preferably, the molar ratio is (0.7-2):

1.

4. The method for preparing cyanoacrylate according to claim 1, wherein The molar ratio of the cyanoacetate, the monobasic ammonium acid and the monobasic carboxylic acid is (0.7-3.0): (0.15-1.5): (0.45-3).

5. The method for preparing cyanoacrylate according to claim 1, characterized in that: The first catalyst includes any one of acetic acid, propionic acid and butyric acid, and the second catalyst includes any one of ammonium acetate, ammonium propionate and ammonium butyrate.

6. The method for preparing a cyanoacrylate according to claim 1, characterized in that: The cyanoacetate includes any one of isooctyl cyanoacetate, methyl cyanoacetate, ethyl cyanoacetate and propyl cyanoacetate; and / or, The carbonyl compound includes any one of benzophenone, a benzophenone derivative and acetophenone.

7. The method for preparing a cyanoacrylate according to claim 1, characterized in that: Before the step of mixing cyanoacetic acid ester, carbonyl compound, first catalyst and second catalyst in a container to carry out condensation reaction to prepare cyanoacrylate ester, the method comprises: Dehydrating cyanoacetic acid under vacuum at 75-90° C. for 1-2 hours, mixing the dehydrated cyanoacetic acid, alkyl alcohol and concentrated sulfuric acid as a catalyst, and performing an esterification reaction at 100-120° C. for 2-6 hours to obtain cyanoacetic acid ester; Wherein, the cyanoacetic acid is a 75% to 85% cyanoacetic acid aqueous solution; The molar ratio of cyanoacetic acid to alkyl alcohol is (0.8-1.5):1; The mass ratio of the cyanoacetic acid to the concentrated sulfuric acid is 1:(0.02-0.1).

8. A preparation system for implementing the method for preparing cyanoacrylate according to any one of claims 1 to 7, characterized in that: The preparation system comprises a reaction unit, a distillation unit, and a separation and recovery unit connected in sequence by pipelines. Wherein, the separation and recovery unit is connected to the reaction unit through a pipeline, and the reaction unit includes a container; The cyanoacetate, the carbonyl compound, the first catalyst and the second catalyst react through the reaction unit; The distillation unit is used to distill the substances in the reaction unit to obtain the first catalyst, the second catalyst and water, and the second catalyst is returned to the reaction unit through the distillation unit; The separation and recovery unit is used to separate the first catalyst from water and introduce the first catalyst into the reaction unit.

9. The preparation system according to claim 8, characterized in that: The distillation unit comprises a distillation tower, and the distillation tower is connected to the container through a pipeline.

10. The preparation system according to claim 8, characterized in that: The separation and recovery unit comprises a condenser, a mixed solvent storage tank, a membrane dehydration device and a water recovery storage tank which are connected in sequence through pipelines. Wherein, the condenser is connected to the distillation tower through a pipeline, and the membrane dehydration device is connected to the reaction unit through a pipeline.

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