A process for the preparation of methyl carboxylate-2-propynyl ester

Abstract

This application provides a method for preparing methylcarboxylic acid-2-propynyl ester, comprising the following steps: (1) mixing dimethyl carbonate and propargyl alcohol, adding a first alkaline catalyst, stirring and heating to a temperature of 90-105°C, and distilling out methanol by reactive distillation to obtain a first component; (2) performing solid-liquid separation on the first component to obtain a first liquid, and performing vacuum distillation on the first liquid to remove propargyl alcohol and dimethyl carbonate to obtain methylcarboxylic acid-2-propynyl ester and residue; (3) performing vacuum distillation on the residue, replenishing dimethyl carbonate and the second alkaline catalyst with the distillate for reaction, and reusing the reaction liquid in step (2). This application uses the transesterification reaction of propargyl alcohol and dimethyl carbonate to synthesize methylcarboxylic acid-2-propynyl ester, which has high safety, low overall reaction temperature, fewer by-products and waste, and high yield.

Description

Technical Field

[0001] This application relates to the technical field of methods for the synthesis and purification of organic compounds, and in particular to a method for preparing a methylcarboxylic acid-2-propynyl ester. Background Technology

[0002] Methylcarboxylic acid-2-propynyl ester is a novel electrolyte additive for lithium-ion batteries. During the charging and discharging process of lithium-ion batteries, conventional electrolytes undergo decomposition reactions on the surface of the positive electrode. However, methylcarboxylic acid-2-propynyl ester can effectively combine with the positive electrode material, forming a dense passivation film on the surface of the positive electrode. This film can suppress the occurrence of side reactions on the electrode surface, enhancing the stability and cycle performance of lithium-ion batteries.

[0003] Currently, there are two main synthetic strategies for methylcarboxylic acid-2-propynyl ester. One strategy uses propargyl alcohol and methyl chloroformate as raw materials, reacting them with a dehydrating agent and catalyst to obtain methylcarboxylic acid-2-propynyl ester. This reaction produces a large amount of hydrogen chloride as a byproduct, resulting in complex tail gas treatment and high equipment corrosivity. Furthermore, the raw material methyl chloroformate is highly toxic, leading to low production safety. The second synthetic strategy uses propargyl alcohol and dimethyl carbonate for transesterification to obtain methylcarboxylic acid-2-propynyl ester. This reaction route is relatively safer, has lower equipment requirements, and offers high synthetic stability, but the overall product yield is unsatisfactory. Therefore, how to reduce the generation of byproducts and waste during the production of methylcarboxylic acid-2-propynyl ester, improve production safety, and simultaneously increase the actual yield of methylcarboxylic acid-2-propynyl ester is a crucial problem that urgently needs to be solved in the current production process of methylcarboxylic acid-2-propynyl ester. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing methylcarboxylic acid-2-propynyl ester, so as to improve the yield in the synthesis process of methylcarboxylic acid-2-propynyl ester and reduce the generation of by-products and waste. The specific technical solution is as follows:

[0005] This application provides a method for preparing methylcarboxylic acid-2-propynyl ester, which includes the following steps:

[0006] (1) Mix dimethyl carbonate and propargyl alcohol, add the first alkaline catalyst, stir and heat to a temperature of 90-105℃, and distill methanol by reaction distillation to obtain the first component; (2) Perform solid-liquid separation on the first component to obtain the first liquid, and perform vacuum distillation on the first liquid to remove propargyl alcohol and dimethyl carbonate to obtain methylcarboxylic acid-2-propargyl ester and residue; (3) Perform vacuum distillation on the residue, and add dimethyl carbonate and the second alkaline catalyst to the distillate for reaction. After filtration, the reaction liquid is reused in step (2).

[0007] In some embodiments of this application, in step (1), the molar ratio of dimethyl carbonate to propargyl alcohol is (1-10):1, preferably (2-5):1.

[0008] In some embodiments of this application, the first alkaline catalyst and the second alkaline catalyst are each independently selected from an alkali metal salt, which is selected from at least one of potassium hydroxide, potassium carbonate, sodium hydroxide and sodium silicate.

[0009] In some embodiments of this application, the mass ratio of the first alkaline catalyst to propargyl alcohol in step (1) is (0.001 to 0.1):1, preferably (0.005 to 0.05):1.

[0010] In some embodiments of this application, in step (1), reactive distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15; in step (2), vacuum distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15.

[0011] In some embodiments of this application, in step (2), the reflux ratio of vacuum distillation is 0.5 to 4, preferably 1 to 3.

[0012] In some embodiments of this application, in step (2), the temperature of vacuum distillation is 50–85°C.

[0013] In some embodiments of this application, in step (3), the temperature of vacuum distillation is 70–130°C, and the temperature of the reaction is 80–105°C.

[0014] In some embodiments of this application, in step (3), the mass ratio of the second alkaline catalyst to the fraction is (0.001 to 0.1):1, preferably (0.005 to 0.01):1.

[0015] In some embodiments of this application, in step (3), the mass ratio of dimethyl carbonate to the fraction is (0.5-5):1, preferably (1-3):1.

[0016] The beneficial effects of this application: This application provides a method for preparing methylcarboxylic acid-2-propynyl ester, comprising the following steps: (1) mixing dimethyl carbonate and propargyl alcohol, adding a first alkaline catalyst, stirring and heating to a temperature of 90-105℃, and distilling out methanol by reactive distillation to obtain a first component; (2) performing solid-liquid separation on the first component to obtain a first liquid, and performing vacuum distillation on the first liquid to remove propargyl alcohol and dimethyl carbonate to obtain methylcarboxylic acid-2-propynyl ester and residue; (3) performing vacuum distillation on the residue, supplementing dimethyl carbonate and a second alkaline catalyst with the distillate for reaction, and reusing the reaction liquid to step (2). This application uses the transesterification reaction of propargyl alcohol and dimethyl carbonate to synthesize methylcarboxylic acid-2-propynyl ester, which has high safety, low overall reaction temperature, less by-products and waste, and high yield.

[0017] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0019] Figure 1 The image shows the 1H NMR spectrum of the product methylcarboxylic acid-2-propynyl ester from Examples 1-2. Detailed Implementation

[0020] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0021] This application provides a method for preparing methylcarboxylic acid-2-propynyl ester, which includes the following steps: (1) mixing dimethyl carbonate and propargyl alcohol, adding a first alkaline catalyst, stirring and heating to a temperature of 90-105°C, and distilling out methanol by reactive distillation to obtain a first component; (2) performing solid-liquid separation on the first component to obtain a first liquid, and performing vacuum distillation on the first liquid to remove propargyl alcohol and dimethyl carbonate to obtain methylcarboxylic acid-2-propynyl ester and residue; (3) performing vacuum distillation on the residue, adding dimethyl carbonate and a second alkaline catalyst to the distillate for reaction, and reusing the reaction liquid in step (2). For example, in step (1), the heating temperature can be 90°C, 95°C, 100°C, 105°C, or a range of any two of these values. This application uses the transesterification reaction of propargyl alcohol and dimethyl carbonate to synthesize methyl carboxylic acid-2-propargyl ester, which has high safety and the overall reaction temperature does not exceed 105℃, which can reduce cost consumption and inhibit the polymerization of methyl carboxylic acid-2-propargyl ester; in step (3), by adding dimethyl carbonate and the second alkaline catalyst to the distillate and then reusing it, the by-product can be further converted into the product, increasing the yield and reducing the generation of by-products and waste.

[0022] In some embodiments of this application, in step (1), the molar ratio of dimethyl carbonate to propargyl alcohol is (1-10):1, preferably (2-5):1. For example, in step (1), the molar ratio of dimethyl carbonate to propargyl alcohol can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or a range consisting of any two of these values. Controlling the molar ratio of dimethyl carbonate to propargyl alcohol within the range specified in this application is beneficial for improving the conversion rate of propargyl alcohol, increasing the selectivity of the reaction, suppressing the formation of by-products, and increasing the yield of methylcarboxylic acid-2-propargyl ester.

[0023] In some embodiments of this application, the first basic catalyst and the second basic catalyst are each independently selected from alkali metal salts, which are selected from at least one of potassium hydroxide, potassium carbonate, sodium hydroxide, and sodium silicate. Catalysts exhibit different activities for different chemical reactions. Using alkali metal salts within the scope of this application as the first and second basic catalysts can further improve the reaction rate.

[0024] In some embodiments of this application, the mass ratio of the first alkaline catalyst to propargyl alcohol in step (1) is (0.001–0.1):1, preferably (0.005–0.05):1. For example, the mass ratio of the first alkaline catalyst to propargyl alcohol in step (1) can be 0.001:1, 0.005:1, 0.01:1, 0.03:1, 0.05:1, 0.07:1, 0.09:1, 0.1:1, or any two of these values. Using an alkali metal salt as the first alkaline catalyst and controlling the mass ratio of the first alkaline catalyst to propargyl alcohol in step (1) within the range of this application is beneficial for the first alkaline catalyst to provide adsorption sites for the transesterification reaction of propargyl alcohol and dimethyl carbonate, adsorb reactant molecules and cause them to interact, reduce the activation energy of the transesterification reaction synthesis of propargyl alcohol and dimethyl carbonate, increase the reaction rate of the transesterification synthesis reaction, and thus increase the conversion rate of propargyl alcohol.

[0025] In some embodiments of this application, in step (1), reactive distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15; in step (2), vacuum distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15. For example, the number of trays in step (1) can be 5, 10, 15, 20, 25, 30, 35, 40, or any two of these values, and the number of trays in step (2) can be 5, 10, 15, 20, 25, 30, 35, 40, or any two of these values. The number of trays provides a contact point for the gas and liquid phases, allowing heat and mass transfer processes to occur. The number of trays directly affects the separation efficiency and the purity of the product. Using a distillation column with trays in the reactive distillation in step (1) and controlling the number of trays within the scope of this application can improve the separation efficiency of methanol; using a distillation column with trays in the vacuum distillation in step (2) and controlling the number of trays within the scope of this application can improve the purity of the product methylcarboxylic acid-2-propynyl ester.

[0026] In some embodiments of this application, in step (2), the reflux ratio of vacuum distillation is 0.5 to 4, preferably 1 to 3. For example, in step (2), the reflux ratio of vacuum distillation can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or a range consisting of any two of these values. Controlling the reflux ratio of vacuum distillation in step (2) within the range of this application ensures a high fractionation rate in the vacuum distillation step, improves the efficiency of vacuum distillation, and simultaneously enhances the purification effect of methylcarboxylic acid-2-propynyl ester.

[0027] In some embodiments of this application, the temperature of vacuum distillation in step (2) is 50–85°C. For example, the reflux ratio of vacuum distillation in step (2) can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 85°C, or a range of any two of these values. By controlling the temperature of vacuum distillation in step (2) within the range of this application, the reaction temperature is lower, which can inhibit the polymerization of methylcarboxylic acid-2-propynyl ester, improve the purity of the methylcarboxylic acid-2-propynyl ester product, reduce cost consumption, and improve production efficiency.

[0028] Temperature and pressure both affect the boiling point of chemical substances. In step (2) of this application, during vacuum distillation, a suitable pressure range can be selected based on the boiling points of propargyl alcohol and dimethyl carbonate and the temperature of vacuum distillation. For example, in some embodiments of this application, in step (2), when the temperature of vacuum distillation is 50°C, the pressure of vacuum distillation is gradually reduced from 60 mbar to 30 mbar, with a pressure change rate of 3 mbar / h to 10 mbar / h. By controlling the pressure and pressure change rate of vacuum distillation, propargyl alcohol and dimethyl carbonate can be separated at a lower temperature to obtain a product with high purity and residue.

[0029] In some embodiments of this application, in step (2), the first component is cooled to 40°C–80°C before solid-liquid separation. The solubility of the first and second alkaline catalysts increases with increasing temperature. Cooling the first component to 40°C–80°C before solid-liquid separation facilitates the precipitation of the first and second alkaline catalysts into solids, thereby increasing the separation rate of the first and second alkaline catalysts and thus improving the purity of the methylcarboxylic acid-2-propynyl ester product. This application does not limit the specific method of solid-liquid separation in step (2), as long as it meets the purpose of this application. For example, the solid-liquid separation in step (2) can be performed by natural sedimentation, filtration, centrifugation, vacuum filtration, etc. After solid-liquid separation in step (2), the solid obtained by solid-liquid separation can be washed with propargyl alcohol or dimethyl carbonate, and the washing liquid can be reused in the liquid to further improve the yield of methylcarboxylic acid-2-propynyl ester.

[0030] In some embodiments of this application, the main components of the residue in step (2) are dipropyne methyl carbonate, methyl carboxylic acid-2-propyne ester and polymeric high-boiling-point substances.

[0031] In some embodiments of this application, in step (3), the temperature of vacuum distillation is 70–130°C, and the temperature of the reaction is 80–105°C. For example, the temperature of vacuum distillation in step (3) can be 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or any two of these values; the temperature of the reaction in step (3) can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, or any two of these values. Controlling the temperature of vacuum distillation in step (3) within the range of this application is beneficial to improving the efficiency of removing high-boiling substances; controlling the temperature of the reaction in step (3) within the range of this application is beneficial to distilling diacetylmethyl carbonate and methylcarboxylic acid-2-propynyl ester, resulting in higher efficiency.

[0032] Temperature and pressure both affect the boiling point of chemical substances. In step (3) of this application, during vacuum distillation, a suitable pressure range can be selected based on the boiling points of diacetylacetyl methyl carbonate, methylcarboxylic acid-2-propynyl ester, and the high-boiling polymer, as well as the temperature of vacuum distillation. For example, in step (3) of this application, the pressure range of vacuum distillation is 15 mbar to 30 mbar. In some embodiments of this application, in step (3), when the temperature of vacuum distillation is 100°C, the pressure of vacuum distillation is 20 mbar. By controlling the pressure of vacuum distillation in step (3), the high-boiling polymer in the residue can be removed at a lower temperature, and diacetylacetyl methyl carbonate and methylcarboxylic acid-2-propynyl ester can be distilled off.

[0033] In some embodiments of this application, in step (3), the mass ratio of the second alkaline catalyst to the distillate is (0.001–0.1):1, preferably (0.005–0.01):1. For example, the mass ratio of the second alkaline catalyst to the distillate in step (3) can be 0.001:1, 0.005:1, 0.007:1, 0.01:1, 0.03:1, 0.05:1, 0.07:1, 0.09:1, 0.1:1, or a range consisting of any two of these values. Controlling the mass ratio of the second alkaline catalyst to the distillate in step (3) within the range specified in this application is beneficial for converting dipropynyl methyl carbonate into methylcarboxylic acid-2-propynyl ester, resulting in higher conversion efficiency.

[0034] In some embodiments of this application, in step (3), the mass ratio of dimethyl carbonate to the distillate is (0.5–5):1, preferably (1–3):1. For example, the mass ratio of dimethyl carbonate to the distillate in step (3) can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any range of two of these values. Controlling the mass ratio of dimethyl carbonate to the distillate in step (3) within the range of this application is beneficial for further converting dipropyne methyl carbonate into methylcarboxylic acid-2-propynyl ester, improving atom utilization, and further increasing the yield of methylcarboxylic acid-2-propynyl ester.

[0035] In step (3) of this application, a distillation apparatus with or without trays can be used. When trays are included, this application does not limit the number of trays for vacuum distillation, as long as the purpose of this application is met.

[0036] In some embodiments of this application, in step (3), the distillate is supplemented with dimethyl carbonate and a second basic catalyst for reaction, and the reaction temperature is 80°C to 105°C. For example, the reaction temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, or a range of any two of these values. By controlling the reaction temperature in step (3), it is beneficial to increase the reaction rate of converting dipropyne methyl carbonate to methylcarboxylic acid-2-propynyl ester, inhibit the polymerization of methylcarboxylic acid-2-propynyl ester, improve the selectivity of the reaction, and reduce the generation of by-products.

[0037] Example

[0038] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0039] Test methods and equipment:

[0040] propargyl alcohol conversion rate

[0041] The mass of propargyl alcohol added in step (1) is recorded as W1. The mass of propargyl alcohol in the first solution of step (1) is measured using the internal standard method of a gas chromatograph (model: Shimadzu 2030) and recorded as W2.

[0042] The conversion rate of propargyl alcohol is calculated as (W1-W2) / W1 × 100%.

[0043] Conversion rate of dipropyne methyl carbonate

[0044] The residue from step (3) was subjected to vacuum distillation, and the fraction was collected. The mass of dipropyne methyl carbonate in the fraction from step (3) was measured using a gas chromatograph (model: Shimadzu 2030) with internal standard method, and recorded as W3. The fraction was then supplemented with dimethyl carbonate and a second basic catalyst for reaction, and the mass of dipropyne methyl carbonate in the resulting component was measured and recorded as W4.

[0045] Conversion rate of dipropyne methyl carbonate = (W3-W4) / W3×100%.

[0046] Yield of methylcarboxylic acid-2-propynyl ester

[0047] The reaction solution from step (3) was filtered and reused in step (2). Then, using a gas chromatograph (model: Shimadzu 2030) with internal standard method, the mass of the methylcarboxylic acid-2-propynyl ester product from step (2) was tested and recorded as W5. W5 represents the actual mass of the methylcarboxylic acid-2-propynyl ester product. The theoretical mass of the produced methylcarboxylic acid-2-propynyl ester product can be calculated based on the amount of propargyl alcohol fed, and recorded as W6.

[0048] Yield of methylcarboxylic acid-2-propynyl ester = W5 / W6 × 100%.

[0049] In this application, the yield of methylcarboxylic acid-2-propynyl ester refers to the yield of methylcarboxylic acid-2-propynyl ester after reusing the reaction solution in step (3) once.

[0050] Example 1-1

[0051] (1) Take 3 moles of dimethyl carbonate and 1 mole of propargyl alcohol, stir well, add potassium carbonate as the first alkaline catalyst, place in a three-necked flask with a 10-plate distillation column, stir and heat, and set the heating temperature to 105℃. The mass ratio of potassium carbonate to propargyl alcohol is 0.03:1. After the vapor temperature at the top of the column reaches 90℃, start the total recovery process. After 4 hours, the conversion rate of propargyl alcohol is tested to be 96%. The component remaining in the three-necked flask after total recovery is the first component.

[0052] (2) After the temperature of the first component drops to 60°C, the first alkaline catalyst is filtered out to obtain the first liquid. The first liquid is subjected to vacuum distillation in a distillation column with 10 trays. The temperature of vacuum distillation is 50°C, and the pressure is gradually reduced from 60 mbar to 30 mbar at a rate of 5 mbar / h. The reflux ratio during vacuum distillation is 1. Dimethyl carbonate and propargyl alcohol are removed to obtain methyl carboxylic acid-2-propargyl ester product. The total time is 6 hours. The residue in the reactor is dipropargyl methyl carbonate, methyl carboxylic acid-2-propargyl ester and polymeric high-boiling substances.

[0053] (3) The residue in the reactor was subjected to vacuum distillation at a temperature of 100℃, a pressure of 20 mbar, and a time of 0.5 hours. The distillate was collected, with a mass of 13.67 g. The distillate was then supplemented with dimethyl carbonate and a second alkaline catalyst, potassium hydroxide, to react at 100℃ for 4 hours, converting diacetylmethyl carbonate into methylcarboxylic acid-2-propynyl ester with a conversion rate of 90%. The mass ratio of dimethyl carbonate to distillate was 2:1, and the mass ratio of potassium hydroxide to distillate was 0.005:1. The reaction solution was recycled to the separation stage to produce methylcarboxylic acid-2-propynyl ester, with a final yield of 99.49% for the entire process.

[0054] Examples 1-2 to Examples 1-3

[0055] Except for changing the heating temperature in step (1) according to Table 1, the rest is the same as in Example 1-1.

[0056] The 1H NMR spectra of the methylcarboxylic acid-2-propynyl ester product prepared in Examples 1-2 are shown below. Figure 1 As shown.

[0057] Examples 1-4 to Examples 1-7

[0058] Except for changing the molar ratio of dimethyl carbonate and propargyl alcohol in step (1) according to Table 1, the rest is the same as in Examples 1-2.

[0059] Examples 1-8 to Examples 1-11

[0060] Except for changing the mass ratio of the first alkaline catalyst and propargyl alcohol in step (1) according to Table 1, the rest is the same as in Examples 1-2.

[0061] Examples 1-12 to Examples 1-15

[0062] Except for changing the mass ratio of dimethyl carbonate to fraction in step (3) according to Table 1, the rest is the same as in Examples 1-2.

[0063] Examples 1-16 to Examples 1-18

[0064] Except for changing the mass ratio of the second alkaline catalyst to the fraction in step (3) according to Table 1, the rest is the same as in Examples 1-2.

[0065] Examples 1-19 to Examples 1-20

[0066] Except for changing the type of the first alkaline catalyst in step (1) and the type of the second alkaline catalyst in step (3) according to Table 1, the rest is the same as in Examples 1-2.

[0067] Examples 2-1 to 2-7

[0068] Except for changing the number of trays in step (1), the number of trays in step (2), and the reflux ratio in step (2) according to Table 2, the rest are the same as in Examples 1-2.

[0069] Examples 2-8

[0070] Except for adjusting the reduced pressure distillation temperature to 85°C according to step (2) in Table 2, the rest is the same as in Examples 1-2.

[0071] Examples 2-9

[0072] Except for adjusting the reduced pressure distillation temperature to 90°C according to step (2) in Table 2, the rest is the same as in Examples 1-2.

[0073] Example 2-10

[0074] Except for adjusting the vacuum distillation temperature to 70°C and the vacuum distillation time to 1.5h according to step (3) in Table 2, the rest is the same as in Examples 1-2.

[0075] Example 2-11

[0076] Except for adjusting the vacuum distillation temperature to 130°C in step (3) according to Table 2, the rest is the same as in Examples 1-2.

[0077] Example 2-12

[0078] Except for adjusting the vacuum distillation temperature to 140°C in step (3) according to Table 2, the rest is the same as in Examples 1-2.

[0079] Example 2-13

[0080] Except for adjusting the reaction temperature to 80°C and the reaction time to 8h according to step (3) in Table 2, the rest is the same as in Examples 1-2.

[0081] Example 2-14

[0082] Except for adjusting the reaction temperature to 105°C in step (3) according to Table 2, the rest is the same as in Examples 1-2.

[0083] Example 2-15

[0084] Except for adjusting the reaction temperature to 110°C in step (3) according to Table 2, the rest is the same as in Examples 1-2.

[0085] Comparative Examples 1 to 2

[0086] Except for adjusting the heating temperature in step (1) according to Table 1, the rest is the same as in Examples 1-2.

[0087] Comparative Example 3

[0088] (1) Take 3 moles of dimethyl carbonate and 1 mole of propargyl alcohol, stir well, add potassium carbonate as the first alkaline catalyst, place in a three-necked flask with a 10-plate distillation column, stir and heat at a preset temperature of 105℃. The mass ratio of potassium carbonate to propargyl alcohol is 0.001:1. After the vapor temperature at the top of the column reaches 100℃, start the total recovery process. After 4 hours, the conversion rate of propargyl alcohol is 99%. The component remaining in the three-necked flask after total recovery is the first component.

[0089] (2) After the temperature of the first component drops to about 60°C, the first alkaline catalyst is filtered out to obtain the first liquid. The first liquid is then subjected to vacuum distillation in a distillation column with 10 trays. The temperature of the vacuum distillation is 50°C, and the pressure is gradually reduced from 60 mbar to 30 mbar at a rate of 5 mbar / h. The reflux ratio during the vacuum distillation process is 1. Dimethyl carbonate and propargyl alcohol are removed to obtain methylcarboxylic acid-2-propargyl ester product. The total time is 6 hours.

[0090] Table 1

[0091]

[0092] In Table 1, " / " indicates that the corresponding preparation parameters or substances do not exist.

[0093] Table 2

[0094]

[0095] As can be seen from Examples 1-1 to 1-20 and Comparative Examples 1 to 3, the method of this application for preparing methylcarboxylic acid-2-propynyl ester has a relatively low overall reaction temperature, and the yield and purity of the methylcarboxylic acid-2-propynyl ester product are both high. In Examples 1-1 to 1-20, the heating temperature in step (1) is within the range of this application, the conversion rate of propargyl alcohol in step (1) is high, and the yield and purity of the methylcarboxylic acid-2-propynyl ester product are both high; the heating temperature in step (1) of Comparative Example 1 is too low, and the conversion rate of propargyl alcohol and the yield of the methylcarboxylic acid-2-propynyl ester product are both low; the heating temperature in step (1) of Comparative Example 2 is too high, causing the methylcarboxylic acid-2-propynyl ester to polymerize, and the yield of the methylcarboxylic acid-2-propynyl ester product also decreases; in Comparative Example 3, the fraction in step (3) was not replenished with dimethyl carbonate and the second alkaline catalyst and then reused in step (2), resulting in a low yield of the methylcarboxylic acid-2-propynyl ester product.

[0096] The molar ratio of dimethyl carbonate to propargyl alcohol can affect the conversion rate of propargyl alcohol, thereby affecting the yield of methylcarboxylic acid-2-propargyl ester product. As can be seen from Examples 1-4 to Examples 1-7, when the molar ratio of dimethyl carbonate to propargyl alcohol is controlled within the range of this application, the conversion rate of propargyl alcohol is higher, and the yield of methylcarboxylic acid-2-propargyl ester product is higher.

[0097] As can be seen from Examples 1-8 to Examples 1-11, when the mass ratio of the first alkaline catalyst and propargyl alcohol in step (1) is controlled within the range of this application, the conversion rate of propargyl alcohol is high and the yield of methylcarboxylic acid-2-propargyl ester product is high.

[0098] As can be seen from Examples 1-12 to 1-15, controlling the mass ratio of dimethyl carbonate to the distillate in step (3) within the range specified in this application is beneficial for further converting dipropyne methyl carbonate into methylcarboxylic acid-2-propynyl ester, thereby improving atom utilization and increasing the yield of methylcarboxylic acid-2-propynyl ester product. As can be seen from Examples 1-16 to 1-18, controlling the mass ratio of the second alkaline catalyst to the distillate in step (3) within the range specified in this application results in a higher conversion rate of dipropyne methyl carbonate and a higher yield of methylcarboxylic acid-2-propynyl ester product.

[0099] As can be seen from Examples 1-19 to Examples 1-20, using the first and second alkaline catalysts within the scope of this application, the conversion rates of propargyl alcohol, dipropargyl methyl carbonate, and methyl carboxylic acid-2-propargyl ester products are all high.

[0100] As can be seen from Examples 2-1 to 2-7, controlling the number of trays and the reflux ratio in steps (1) and (2) within the range of this application is beneficial to improving the yield of methylcarboxylic acid-2-propynyl ester. As can be seen from Examples 2-8 to 2-15, keeping the vacuum distillation temperature in step (2), the vacuum distillation temperature in step (3), and the reaction temperature in step (3) within the range of this application results in a higher conversion rate of dipropynyl methyl carbonate and a higher yield of methylcarboxylic acid-2-propynyl ester.

[0101] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a methylcarboxylic acid-2-propynyl ester, comprising the following steps: (1) Mix dimethyl carbonate and propargyl alcohol, add the first alkaline catalyst, stir and heat to a temperature of 90-105℃, and distill methanol by reactive distillation to obtain the first component; (2) The first component is subjected to solid-liquid separation to obtain a first liquid. The first liquid is subjected to vacuum distillation to remove propargyl alcohol and dimethyl carbonate to obtain methylcarboxylic acid-2-propargyl ester and residue. (3) The residue in the reactor is subjected to vacuum distillation. The fraction is used to supplement dimethyl carbonate and a second alkaline catalyst for reaction. The reaction solution is reused in step (2).

2. The method according to claim 1, wherein, In step (1), the molar ratio of dimethyl carbonate to propargyl alcohol is (1-10):1, preferably (2-5):

1.

3. The method according to claim 1, wherein, The first alkaline catalyst and the second alkaline catalyst are each independently selected from alkali metal salts, wherein the alkali metal salt is selected from at least one of potassium hydroxide, potassium carbonate, sodium hydroxide and sodium silicate.

4. The method according to claim 1, wherein, The mass ratio of the first alkaline catalyst to the propargyl alcohol in step (1) is (0.001-0.1):1, preferably (0.005-0.05):

1.

5. The method according to claim 1, wherein, In step (1), the reactive distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15; in step (2), the vacuum distillation uses a distillation column with trays, the number of trays being 5 to 40, preferably 5 to 15.

6. The method according to claim 1, wherein, In step (2), the reflux ratio of the vacuum distillation is 0.5 to 4, preferably 1 to 3.

7. The method according to claim 1, wherein, In step (2), the temperature of the vacuum distillation is 50-85°C.

8. The method according to claim 1, wherein, In step (3), the temperature of the vacuum distillation is 70-130°C, and the temperature of the reaction is 80-105°C.

9. The method according to claim 1, wherein, In step (3), the mass ratio of the second alkaline catalyst to the fraction is (0.001-0.1):1, preferably (0.005-0.01):

1.

10. The method according to claim 1, wherein, In step (3), the mass ratio of dimethyl carbonate to the fraction is (0.5-5):1, preferably (1-3):1.

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