Preparation method of acrylic isocyanate

Abstract

The embodiment of the invention discloses a preparation method of acrylic isocyanate ester, which comprises the following steps: reacting substituted or unsubstituted acrylic acid as shown in a formula I with bromoethanol under the action of acid to obtain an intermediate mixture, and reacting the intermediate mixture with sodium cyanate under the action of a catalyst to prepare the acrylic isocyanate ester as shown in a formula II. According to the embodiment of the invention, the bromoethanol is used as a raw material to react with the substituted or unsubstituted acrylic acid, and then reacts with the sodium cyanate under the action of the catalyst to prepare the isocyanate acrylate with different substituent groups, so that the method is simple in process, low in equipment requirement, environment-friendly in material, low in cost, high in yield and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for preparing acrylic isocyanate esters. Background Technology

[0002] (Meth)acrylate compounds, represented by acryloyloxyethyl isocyanate and methacryloyloxyethyl isocyanate, are used in coatings (coating materials), adhesives, photoresists, dental materials, magnetic recording materials, etc., due to the presence of highly reactive isocyanate groups and alkene double bonds within a single molecule. They are extremely useful compounds in industry.

[0003] Currently, the common method for preparing acrylic isocyanate esters involves using acrylic acid with different substituents as a raw material. First, it reacts with phosgene to obtain propionyl chloride with different substituents. Then, it reacts sequentially with ethanolamine hydrochloride and phosgene to obtain chloropropionic acid (2-ethyl isocyanate) esters with different substituents. Finally, it undergoes a triethylamine-catalyzed elimination reaction to obtain the acrylate isocyanate with different substituents. This method uses highly toxic phosgene, and the intermediates need to be separated, making the process cumbersome and unsuitable for industrial production.

[0004] Another method for preparing ethyl isocyanates of acrylates is as follows: ethanolamine and ethyl chloroformate are first reacted to generate ethyl ethanolamine formate, which is then reacted with acryloyl chlorides with different substituents at a temperature of 80℃-100℃ to generate ethyl acryloyloxyethyl formates with different substituents. Then, phosphorus pentachloride, phosphorus oxychloride, etc., are used to generate ethyl acrylates with different substituents. This process is relatively cumbersome, has a low yield, requires a large amount of raw materials, and has high production costs, making it unsuitable for industrial production. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing acrylic isocyanate esters, to address the problem that the current preparation of acrylic isocyanate esters is difficult to industrialize due to the highly toxic materials, cumbersome operation, and low yield.

[0006] Specifically, the present invention provides a method for preparing acrylic isocyanate esters, comprising: Acrylic acid of Formula I, with substituted or unsubstituted form, is reacted with bromoethanol in the presence of an acid to obtain an intermediate mixture. This intermediate mixture is then reacted with sodium cyanate in the presence of a catalyst to prepare the isocyanate ester of Formula II. ; R includes hydrogen or methyl.

[0007] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the acid includes at least one selected from methanesulfonic acid, p-toluenesulfonic acid, acetic acid, formic acid, oxalic acid, and sulfuric acid.

[0008] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the molar ratio of the substituted or unsubstituted acrylic acid, the acid, and the bromoethanol is 1:(0.01-0.1):(1-1.5).

[0009] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the reaction temperature of the substituted or unsubstituted acrylic acid with bromoethanol under acidic conditions is 80–110°C.

[0010] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the substituted or unsubstituted acrylic acid reacts with bromoethanol in the presence of an acid in a first solvent, wherein the first solvent includes at least one of toluene, n-heptane, and methylcyclohexane.

[0011] In some embodiments of the above-described method for preparing acrylic isocyanate esters, after the substituted or unsubstituted acrylic acid of Formula I reacts with bromoethanol under acidic conditions to obtain an intermediate mixture, the method further includes: The first solvent is removed from the intermediate mixture to obtain an intermediate crude product; The intermediate mixture, under the action of a catalyst, reacts with sodium cyanate to prepare the acrylic isocyanate ester of Formula II, including: The intermediate crude product is reacted with sodium cyanate under the action of a catalyst to prepare an acrylic isocyanate ester of Formula II.

[0012] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the intermediate crude product is reacted with sodium cyanate in a second solvent under the action of a catalyst. The second solvent includes at least one of toluene, xylene, chlorobenzene, and p-chlorotrifluorotoluene.

[0013] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the catalyst includes at least one of tin tetrachloride, ferric chloride, aluminum chloride, zinc chloride, cadmium chloride, and titanium tetrachloride.

[0014] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the molar ratio of the catalyst, the sodium cyanate, and the substituted or unsubstituted acrylic acid is (0.01-0.2):(1-2):1.

[0015] In some embodiments of the above-described method for preparing acrylic isocyanate esters, the reactions were all carried out under an inert atmosphere.

[0016] The above-described one or more embodiments of the present invention have at least one or more of the following beneficial effects: using bromoethanol as a raw material, reacting with substituted or unsubstituted acrylic acid, and then reacting with sodium cyanate under the action of a catalyst to prepare acrylate isocyanate esters with different substituents, the process is simple, the equipment requirements are low, the materials are environmentally friendly, the cost is low, the yield is high, and it is suitable for large-scale industrial production.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0018] The following describes some embodiments of the present invention. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0019] As described in the background section, there are currently two main methods for preparing acrylic isocyanate esters. One method uses acrylic acid as a raw material, which requires the use of highly toxic phosgene and the separation of intermediates, making the process cumbersome. The other method involves first reacting ethanolamine and ethyl chloroformate to generate ethyl ethanolamine formate, which then reacts with acryloyl chloride with different substituents to generate ethyl acryloyloxyethyl formate with different substituents. Finally, phosphorus pentachloride, phosphorus oxychloride, etc., are used to generate acrylic isocyanate esters with different substituents. This method is relatively complicated, has low yield, requires a lot of raw materials, and has high production costs. Neither of these methods is suitable for large-scale industrial production.

[0020] To address the aforementioned problems, this invention creatively proposes a method for preparing acrylic isocyanate esters. Using bromoethanol as a raw material, it reacts with substituted or unsubstituted acrylic acid, and then, under the action of a catalyst, reacts with sodium cyanate to prepare acrylic isocyanate esters with different substituents. The process is simple, requires minimal equipment, uses environmentally friendly materials, has low cost, and high yield, making it suitable for large-scale industrial production.

[0021] The present invention will be specifically described below through specific embodiments.

[0022] Specifically, this invention provides a method for preparing acrylic isocyanate esters, comprising: Acrylic acid of Formula I, with substituted or unsubstituted form, is reacted with bromoethanol in the presence of an acid to obtain an intermediate mixture. This intermediate mixture is then reacted with sodium cyanate in the presence of a catalyst to prepare the isocyanate ester of Formula II. ; R includes hydrogen or methyl.

[0023] The method for preparing acrylic isocyanate esters provided in this application first involves an esterification reaction between acrylic acid or the carboxyl group of acrylic acid substituted with the hydroxyl group of bromoethanol under acid catalysis, generating an acrylate intermediate containing bromoethyl groups. Then, the cyanate ions generated by sodium cyanate (OCN) are used to further prepare the ester. - By replacing the bromine atom, an isocyanate ester structure is formed, ultimately yielding an acrylic isocyanate ester.

[0024] Bromoethanol has the molecular formula C2H5BrO. It is a bifunctional reagent that combines the reactivity of bromoalkane with the properties of alcohol. Although bromoethanol is irritating, its toxicity is far lower than that of highly toxic phosgene.

[0025] The term "unsubstituted acrylic acid" refers to acrylic acid in which all hydrogen atoms in the hydrocarbon backbone remain unchanged and are not replaced by any other atoms or groups. Substituted acrylic acid, on the other hand, refers to acrylic acid in which hydrogen atoms in the hydrocarbon backbone have been replaced by other atoms or groups.

[0026] In this application, acrylic acid is as shown in Formula I, wherein a hydrogen atom at the end of the hydrocarbon backbone of the substituted acrylic acid is replaced by a methyl group to form methacrylic acid.

[0027] The term "acid" refers to a compound that, upon ionization, produces only hydrogen ions (H+). Acids can be classified according to their degree of ionization as strong acids and weak acids, or according to their constituent elements as inorganic acids formed by the combination of non-metallic elements and hydrogen, and organic acids containing carbon. Acids can activate carboxyl groups, promote the formation of ester groups, and inhibit side reactions.

[0028] In some embodiments, the acid includes at least one selected from methanesulfonic acid, p-toluenesulfonic acid, acetic acid, formic acid, oxalic acid, and sulfuric acid.

[0029] Methanesulfonic acid and p-toluenesulfonic acid are non-oxidizing, while oxalic acid is reducing. Both can protect the carbon-carbon double bonds of substituted or unsubstituted acrylic acid, preventing polymerization or oxidation. Furthermore, p-toluenesulfonic acid and oxalic acid are solids and can be initially removed by filtration after the reaction. Acetic acid and formic acid are volatile and can be removed. Compared to other strong acids such as nitric acid, the dosage and post-treatment are easier to control. Sulfuric acid has extremely high catalytic efficiency, fast reaction rate, and short reaction time; it is also very low in cost, making it suitable for large-scale industrial production. A small amount can achieve the ideal catalytic effect.

[0030] In some embodiments, the molar ratio of the substituted or unsubstituted acrylic acid, the acid, and the bromoethanol is 1:(0.01–0.1):(1–1.5). Optionally, the molar ratio of the substituted or unsubstituted acrylic acid, the acid, and the bromoethanol can be 1:0.01:1, 1:0.05:1.1, 1:0.07:1, 1:0.01:1.5, 1:0.1:1, 1:0.1:1.5, 1:0.08:1.5, or any value within the range of the above ratios.

[0031] Since only a small amount of acid is needed to fully activate the carboxyl groups of acrylic acid to meet the requirements of the esterification reaction, the amount of acid is controlled at 0.01–0.1 eq of acrylic acid. This satisfies the catalytic requirements of the esterification reaction while avoiding the hydrolysis of bromoethanol due to excess acid, and also prevents the acrylic acid double bonds from polymerizing in a strongly acidic environment. Furthermore, the small amount of acid is easily removed through neutralization and washing, leaving no residue that could deactivate the catalyst in the subsequent reaction with sodium cyanate. The amount of bromoethanol is 1–1.5 eq of acrylic acid, and a slight excess of bromoethane promotes complete conversion of acrylic acid, reduces raw material residue, and the excess ratio is controllable, avoiding the separation burden caused by excessive bromoethanol. Excess bromoethanol can be easily recovered and reused through distillation without additional purification costs. Bromoethanol is a reaction substrate, and a suitable excess can compensate for any slight hydrolysis loss, ensuring the effective substrate concentration in the reaction system.

[0032] In some embodiments, the reaction temperature of the substituted or unsubstituted acrylic acid with bromoethanol under acidic conditions is 80–110°C. Optionally, the reaction temperature of the substituted or unsubstituted acrylic acid with bromoethanol under acidic conditions can be 80°C, 87°C, 90°C, 95°C, 100°C, 106°C, 110°C, or any value within the above range.

[0033] In some embodiments, the substituted or unsubstituted acrylic acid reacts with bromoethanol in the presence of an acid in a first solvent, the first solvent comprising at least one of toluene, n-heptane, and methylcyclohexane.

[0034] Toluene, n-heptane, and methylcyclohexane are all nonpolar or weakly polar organic solvents and are all aprotic solvents. They can fully dissolve acrylic acid and bromoethanol substrates, improve the homogeneity of the reaction system, accelerate the reaction rate, and, since aprotic solvents do not donate protons or promote the hydrolysis of hydroxyl groups in bromoethanol, they reduce the formation of impurities. The esterification reaction of acrylic acid and bromoethanol produces water, and toluene, n-heptane, and methylcyclohexane are poorly soluble in water and have significantly different boiling points from water. A water separator can be used to promptly separate the water generated in the reaction from the system, promoting the esterification reaction to proceed to the forward equilibrium and significantly improving the yield of the target ester intermediate.

[0035] In some embodiments, after the substituted or unsubstituted acrylic acid of Formula I reacts with bromoethanol under acidic conditions to obtain an intermediate mixture, the method further includes: The first solvent is removed from the intermediate mixture to obtain an intermediate crude product; The intermediate mixture, under the action of a catalyst, reacts with sodium cyanate to prepare the acrylic isocyanate ester of Formula II, including: The intermediate crude product is reacted with sodium cyanate under the action of a catalyst to prepare an acrylic isocyanate ester of Formula II.

[0036] Specifically, after the substituted or unsubstituted acrylic acid shown in Formula I reacts with bromoethanol in the first solvent under the action of acid, an intermediate mixture containing the target ester intermediate and impurities, as well as the first solvent, is obtained. Considering that the presence of excess solvent will dilute the concentration of the target ester intermediate and sodium cyanate in the subsequent reaction system and reduce the reaction rate, and that some solvent may interact with the catalyst in the subsequent reaction and weaken the catalyst activity, and in order to facilitate the subsequent purification of the product, the first solvent is removed after the first step reaction is completed.

[0037] Solvent removal can be performed using methods such as vacuum distillation and rotary evaporation, and this application does not specifically limit the methods used in this embodiment. For example, vacuum distillation can be used. The intermediate mixture containing the first solvent and the target ester intermediate is transferred to a vacuum distillation apparatus. 0.1% by weight of a polymerization inhibitor is added to prevent the polymerization of acrylate double bonds. The vacuum pump is started, and the vacuum level is gradually adjusted to the target range to avoid a sudden increase in vacuum that could cause the system to boil violently. The temperature is slowly raised to the set temperature and maintained at a constant temperature during distillation. The distilled solvent is collected after condensation. Distillation is stopped when the volume of the distillate is less than 5 mL every 10 minutes and the system temperature begins to rise slightly. Low-temperature solvent removal lowers the boiling point of the system, preventing the target ester intermediate from decomposing at high temperatures. Solvent removal under vacuum is quick and suitable for industrial-scale operation.

[0038] It should be noted that the examples above are for illustrative purposes only and are not intended to limit the scope of protection of this application. Any modifications / adjustments / updates made based on the teachings of this application are within the scope of protection of this application.

[0039] In some embodiments, the intermediate crude product is reacted with sodium cyanate in the presence of a catalyst in a second solvent, the second solvent comprising at least one of toluene, xylene, chlorobenzene, and p-chlorotrifluorotoluene.

[0040] Toluene, xylene, chlorobenzene, and p-chlorotrifluorotoluene are all aprotic solvents, which can effectively dissolve ester intermediates. They also stabilize the cyanate ion (-OCN) dissociated from sodium cyanate through solvation, enhancing its nucleophilic activity and accelerating the bromine substitution reaction. The solvent environment is stable and will not induce the dissimilation of cyanate ion (-OCN) to isocyanate ion (-NCO), ensuring that the product is an acrylic isocyanate ester rather than an isomeric impurity. Furthermore, the boiling points of these solvents are moderate: toluene 110.6℃, xylene 138–144℃, chlorobenzene 131.7℃, and p-chlorotrifluorotoluene 152℃. The reaction is easily temperature-controlled, requiring no extreme conditions, and can be carried out at reflux temperature. The significant difference between the solvent and product boiling points facilitates subsequent distillation separation.

[0041] In some embodiments, the catalyst includes at least one of tin tetrachloride, ferric chloride, aluminum chloride, zinc chloride, cadmium chloride, and titanium tetrachloride.

[0042] Tin tetrachloride, ferric chloride, aluminum chloride, zinc chloride, cadmium chloride, and titanium tetrachloride are all Lewis acidic metal chlorides, which can be converted to phosphorus by Sn. 4+ Fe 3+ Al 3+ The metal ions coordinate with the bromine atom in the target ester intermediate, activating the C-Br bond. The activated C-Br bond is more susceptible to attack by the cyanate ion (-OCN), significantly lowering the activation energy of the nucleophilic substitution reaction, accelerating the reaction rate, and shortening the reaction time. Furthermore, it exhibits high selectivity, preferentially activating the C-Br bond and avoiding interaction with the carbon-carbon double bond, ester group, or the generated isocyanate group (-NCO) of the acrylate, thus preventing side reactions such as double bond polymerization, ester bond hydrolysis, or cyanate isomerization. Moreover, the catalyst is easy to weigh and add, requiring no complex activation steps, making it suitable for large-scale industrial production due to its low operational threshold.

[0043] In some embodiments, the molar ratio of the catalyst, the sodium cyanate, and the substituted or unsubstituted acrylic acid is (0.01–0.2):(1–2):1. Optionally, the molar ratio of the catalyst, the sodium cyanate, and the substituted or unsubstituted acrylic acid can be 0.01:1:1, 0.01:1.3:1, 0.01:2:1, 0.1:1:1, 0.1:2:1, 0.1:1.5:1, 0.2:1:1, 0.2:1.6:1, 0.2:2:1, or any ratio within the above range. Lewis acid metal chlorides exhibit high catalytic activity, requiring only 0.01–0.2 eq of the substrate acrylic acid to fully activate the C-Br bond and efficiently drive the cyanate substitution reaction without the need for excess. Excess catalyst may trigger side reactions such as ester bond hydrolysis and cyanate isomerization. This range allows for precise control of the catalytic intensity, making it particularly suitable for catalysts with different activities. Excess sodium cyanate promotes complete reaction, controls impurities, and accelerates conversion. Dosage not exceeding 2 eq avoids sodium cyanate buildup, reducing the burden on subsequent separation. For sterically hindered substituted acrylate intermediates, 2 eq of sodium cyanate can increase the reaction rate, ensuring complete substitution without requiring adjustments to other process parameters.

[0044] In some embodiments, the reactions are carried out under an inert atmosphere. The term "inert atmosphere" refers to an oxygen-free environment composed of inert gases such as nitrogen and argon. An inert atmosphere creates an oxygen-free, water-free, and inert operating environment, primarily to protect substances sensitive to air or moisture.

[0045] An inert atmosphere protects Lewis acid catalysts such as tin tetrachloride, ferric chloride, and titanium tetrachloride from oxidation by oxygen in the air. It also prevents the isocyanate groups (-NCO) in the product, acrylate isocyanate, from reacting with moisture in the air to form urea impurities, and prevents the carbon-carbon double bonds of the acrylate from oxidizing or self-polymerizing in an aerobic environment. Furthermore, since the second solvent is often a flammable liquid, an inert atmosphere can replace air as the gaseous environment of the reaction system, reducing the risk of solvent vapors forming an explosive mixture with oxygen and improving operational safety.

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0047] Example 1: This example provides a method for preparing ethyl isocyanate acrylate using acrylic acid as a raw material, toluene as a solvent, p-toluenesulfonic acid as an acid, and bromoethanol as a reactant. After solvent removal, the acrylate is reacted with sodium cyanate in toluene using tin tetrachloride as a catalyst. The synthesis reaction formula is as follows: .

[0048] Under a nitrogen atmosphere, 72 g of acrylic acid was added to 288 g of toluene, along with 17.2 g of p-toluenesulfonic acid and 187.5 g of bromoethanol. The mixture was heated to 110 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 216 g of toluene, 2.65 g of tin chloride, and 130 g of sodium cyanate were added. The mixture was heated to 100 °C and reacted for 7 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was distilled to obtain 118.2 g of product with a purity of 98.9% and a yield of 83.8%.

[0049] Example 2: This example provides a method for preparing ethyl isocyanate of acrylate by reacting acrylic acid as a raw material, n-heptane as a solvent, sulfuric acid as an acid, and bromoethanol, followed by solvent removal, and then reacting with sodium cyanate in chlorobenzene using aluminum chloride as a catalyst. The synthesis reaction formula is as follows: .

[0050] Under a nitrogen atmosphere, 72 g of acrylic acid was added to 288 g of n-heptane, along with 0.98 g of sulfuric acid and 125 g of bromoethanol. The mixture was heated to 98 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 216 g of chlorobenzene, 2.67 g of aluminum chloride, and 65 g of sodium cyanate were added. The mixture was heated to 90 °C and reacted for 8 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was purified by distillation to obtain 115.9 g of product with a purity of 99.0% and a yield of 82.2%.

[0051] Example 3: This example provides a method for preparing ethyl isocyanate acrylate by reacting acrylic acid as a raw material, methylcyclohexane as a solvent, formic acid as an acid, and bromoethanol, followed by solvent removal, and then reacting with sodium cyanate in xylene using zinc chloride as a catalyst. The synthesis reaction formula is as follows: .

[0052] Under a nitrogen atmosphere, 72 g of acrylic acid was added to 288 g of methylcyclohexane, along with 4.6 g of formic acid and 150 g of bromoethanol. The mixture was heated to 80 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 216 g of xylene, 27.2 g of zinc chloride, and 78 g of sodium cyanate were added. The mixture was heated to 80 °C and reacted for 11 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was distilled to obtain 120.1 g of product with a purity of 98.5% and a yield of 85.2%.

[0053] Example 4: This example provides a method for preparing ethyl isocyanate of methacrylate using methacrylic acid as a raw material, toluene as a solvent, acetic acid as an acid, and bromoethanol as a reactant. After solvent removal, the mixture is then reacted in toluene with cadmium chloride as a catalyst and sodium cyanate. The synthetic reaction formula is as follows: .

[0054] Under a nitrogen atmosphere, 86 g of methacrylic acid was added to 258 g of toluene, along with 3 g of acetic acid and 150 g of bromoethanol. The mixture was heated to 90 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 258 g of xylene, 9.2 g of cadmium chloride, and 78 g of sodium cyanate were added. The mixture was heated to 90 °C and reacted for 10 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was distilled to obtain 130.5 g of product with a purity of 98.7% and a yield of 84.2%.

[0055] Example 5: This example provides a method for preparing ethyl isocyanate of methacrylate using methacrylic acid as a raw material, toluene as a solvent, methanesulfonic acid as an acid, and bromoethanol. After solvent removal, the mixture is reacted with sodium cyanate in p-chlorotrifluorotoluene using ferric chloride as a catalyst. The synthetic reaction formula is as follows: .

[0056] Under a nitrogen atmosphere, 86 g of methacrylic acid was added to 258 g of toluene, along with 4.8 g of methanesulfonic acid and 150 g of bromoethanol. The mixture was heated to 90 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 258 g of p-chlorotrifluorotoluene, 3.3 g of ferric chloride, and 78 g of sodium cyanate were added. The mixture was heated to 100 °C and reacted for 9 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was distilled to obtain 125.3 g of product with a purity of 98.2% and a yield of 80.8%.

[0057] Example 6: This example provides a method for preparing ethyl isocyanate of methacrylate using methacrylic acid as a raw material, n-heptane as a solvent, oxalic acid as an acid, and bromoethanol as a reactant. After solvent removal, the methacrylic acid is reacted with sodium cyanate in chlorobenzene using titanium tetrachloride as a catalyst. The synthetic reaction formula is as follows: .

[0058] Under a nitrogen atmosphere, 86 g of methacrylic acid was added to 258 g of n-heptane, along with 1.4 g of oxalic acid and 150 g of bromoethanol. The mixture was heated to 95 °C to remove water. After the reaction reached its endpoint, the solvent was removed, and 258 g of chlorobenzene, 1.9 g of titanium tetrachloride, and 78 g of sodium cyanate were added. The mixture was heated to 80 °C and reacted for 12 hours. After cooling to room temperature, the mixture was filtered, the solvent was removed, and the product was distilled to obtain 128.8 g of product with a purity of 98.6% and a yield of 83.1%.

[0059] As can be seen from the above embodiments, the preparation method of ethyl isocyanate of acrylic acid provided in this application is simple, requires low equipment, is environmentally friendly, has low cost, and high yield, and can be industrialized.

[0060] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing an acrylic isocyanate ester, characterized in that, include: Acrylic acid of Formula I, with substituted or unsubstituted form, is reacted with bromoethanol in the presence of an acid to obtain an intermediate mixture. This intermediate mixture is then reacted with sodium cyanate in the presence of a catalyst to prepare the isocyanate ester of Formula II. ； R includes hydrogen or methyl.

2. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, The acid includes at least one of methanesulfonic acid, p-toluenesulfonic acid, acetic acid, formic acid, oxalic acid, and sulfuric acid.

3. The method for preparing acrylic isocyanate esters according to claim 1 or 2, characterized in that, The molar ratio of the substituted or unsubstituted acrylic acid, the acid, and the bromoethanol is 1:(0.01-0.1):(1-1.5).

4. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, The reaction temperature of the substituted or unsubstituted acrylic acid with bromoethanol under acidic conditions is 80℃~110℃.

5. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, The substituted or unsubstituted acrylic acid reacts with bromoethanol in the presence of an acid in a first solvent, wherein the first solvent includes at least one of toluene, n-heptane, and methylcyclohexane.

6. The method for preparing acrylic isocyanate esters according to claim 5, characterized in that, After reacting the substituted or unsubstituted acrylic acid of Formula I with bromoethanol under acidic conditions to obtain an intermediate mixture, the method further includes: The first solvent is removed from the intermediate mixture to obtain an intermediate crude product; The intermediate mixture, under the action of a catalyst, reacts with sodium cyanate to prepare the acrylic isocyanate ester of Formula II, including: The intermediate crude product is reacted with sodium cyanate under the action of a catalyst to prepare an acrylic isocyanate ester of Formula II.

7. The method for preparing acrylic isocyanate esters according to claim 6, characterized in that, The intermediate crude product reacts with sodium cyanate in the presence of a catalyst in a second solvent, which includes at least one of toluene, xylene, chlorobenzene, and p-chlorotrifluorotoluene.

8. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, The catalyst includes at least one of tin tetrachloride, ferric chloride, aluminum chloride, zinc chloride, cadmium chloride, and titanium tetrachloride.

9. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, The molar ratio of the catalyst, the sodium cyanate, and the substituted or unsubstituted acrylic acid is (0.01-0.2):(1-2):

1.

10. The method for preparing acrylic isocyanate esters according to claim 1, characterized in that, All reactions were carried out under an inert atmosphere.

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