Process for the preparation of polycyclic heterocyclic esters
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGDE GUOTAI HUARONG NEW MATERIAL CO LTD
- Filing Date
- 2024-12-04
- Publication Date
- 2026-06-05
AI Technical Summary
[0020] The advantages of this invention are: it provides a method for preparing polycyclic heterocyclic esters, which has a simple process route, few steps, low purification difficulty, and high product purity, reaching over 99%, which meets the purity requirements of additives for lithium-ion battery electrolytes.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of compound synthesis technology, and more specifically to a method for preparing polycyclic heterocyclic esters. Background Technology
[0002] Electrolyte systems, a crucial component of lithium-ion batteries, are constantly evolving. Research on electrolyte systems, including lithium salts, novel organic solvents, and electrolyte additives, is ongoing. Additives, in particular, are receiving widespread attention due to their significant impact on battery performance.
[0003] The applicant is primarily engaged in the production and research and development of related electrolytes and electrolyte additives. To further improve electrolyte performance, the applicant is conducting further research and development on polycyclic heterocyclic esters. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing polycyclic heterocyclic esters, which has a simple process route, few steps, low purification difficulty, and high product purity.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing polycyclic heterocyclic esters, wherein a hexahydrol is used to perform transesterification with an ester; wherein the ester is selected from one, two, or three of ethylene carbonate, ethylene sulfite, and ethylene sulfate;
[0006] Ethylene carbonate structure:
[0007]
[0008] Vinyl sulfite structure:
[0009]
[0010] Vinyl sulfate structure:
[0011]
[0012] One ester was selected for a one-step transesterification reaction, with a molar ratio of ester to hexahydrol of 3.3:1.
[0013] When two esters are selected, a two-step transesterification reaction is carried out. In the first transesterification reaction, the molar ratio of ester to hexahydrol is 2.0:1, and in the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 1.1:1; or in the first transesterification reaction, the molar ratio of ester to hexahydrol is 1:1, and in the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 2.2:1.
[0014] When three esters are selected, a three-step transesterification reaction is carried out. In the first transesterification reaction, the molar ratio of ester to hexahydrol is 1:1. In the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 1:1. In the third transesterification reaction, the molar ratio of ester to intermediate obtained in the second step is 1.1:1.
[0015] Furthermore, in the aforementioned method for preparing a polycyclic heterocyclic ester, when ethylene carbonate is used in the transesterification reaction, the pH of the reaction system is adjusted to 8-10, and the reaction is heated to 70-120°C.
[0016] Furthermore, in the aforementioned method for preparing a polycyclic heterocyclic ester, when vinyl sulfite is used in the transesterification reaction, the pH of the reaction system is adjusted to 4-6, and the reaction is heated to 70-120°C.
[0017] Furthermore, in the aforementioned method for preparing a polycyclic heterocyclic ester, when vinyl sulfate is used in the transesterification reaction, the pH of the reaction system is adjusted to 6.5-7.5, and the reaction is heated to 70-120°C.
[0018] Furthermore, in the aforementioned method for preparing a polycyclic heterocyclic ester, the pH of the reaction system is adjusted using one or more of citric acid, acetic acid, sodium carbonate, and sodium bicarbonate.
[0019] Furthermore, in the aforementioned method for preparing a polycyclic heterocyclic ester, a buffer is added to the reaction system to maintain the pH, wherein the buffer is selected from one or more of 3-morpholinopropanesulfonic acid, tris(hydroxymethyl)aminomethane, 4-hydroxyethylpiperazine ethanesulfonic acid, and acetic acid-sodium acetate.
[0020] The advantages of this invention are: it provides a method for preparing polycyclic heterocyclic esters, which has a simple process route, few steps, low purification difficulty, and high product purity, reaching over 99%, which meets the purity requirements of additives for lithium-ion battery electrolytes. Attached Figure Description
[0021] Figure 1 This is the 1H NMR spectrum of the product obtained in Example 1.
[0022] Figure 2 This is the carbon NMR spectrum of the product obtained in Example 1. Detailed Implementation
[0023] The preparation method of a polycyclic heterocyclic ester according to the present invention will be described in detail below through specific embodiments.
[0024] Example 1: 182g of sorbitol and 248g of vinyl sulfate were mixed and the pH was adjusted to 6.5 with sodium carbonate and acetic acid. Acetic acid-sodium acetate buffer was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 275g of intermediate was obtained, with a yield of 90%.
[0025] 31g of the intermediate was mixed with 9.7g of ethylene carbonate. The pH was adjusted to 8 with sodium bicarbonate, and tris(hydroxymethyl)aminomethane was added for further adjustment. The mixture was heated to 70℃ for the second step of transesterification. After transesterification, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 28g of the final product with a purity of 99.7% and a yield of 88%. The 1H NMR spectrum of the product is shown below. Figure 1 As shown, see the carbon NMR spectrum. Figure 2 As shown.
[0026] Example 2: 182g of mannitol and 124g of vinyl sulfate were mixed and the pH was adjusted to 6.8 with sodium bicarbonate and citric acid. 3-morpholinopropanesulfonic acid was added to assist in the adjustment. The temperature was raised to 70°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 212g of intermediate was obtained, with a yield of 87%.
[0027] 24.4g of intermediate was mixed with 24g of vinyl sulfite, the pH was adjusted to 6 with acetic acid, and acetic acid-sodium acetate was added for auxiliary adjustment. The temperature was raised to 90℃ for the second step of transesterification. After the transesterification was completed, dimethyl carbonate was added to dissolve the product, and the ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 30g of finished product with a purity of 99.5% and a yield of 90%.
[0028] Example 3: 182g of sweet alcohol and 88g of ethylene carbonate were mixed and the pH was adjusted to 9 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. The sweet alcohol and ethylene glycol were washed away with water. After thorough drying, 187g of intermediate was obtained, with a yield of 90%.
[0029] 41.6g of intermediate one was mixed with 24.8g of vinyl sulfate. The pH was adjusted to 7.5 with acetic acid and sodium bicarbonate. 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The mixture was heated to 90℃ for the second transesterification step. After the second transesterification step was completed, ethyl acetate was added to dissolve the product. Ethyl glycol residue was washed away with water. After thorough drying, 45.9g of intermediate two was obtained, with a yield of 85%.
[0030] 27g of intermediate II was mixed with 12g of vinyl sulfite. The pH was adjusted to 6 with acetic acid, and sodium acetate was added for further adjustment. The mixture was heated to 90℃ for the third transesterification step. After the third transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 28g of the final product with a purity of 99.6% and a yield of 87%.
[0031] Example 4: 182g of sorbitol and 88g of ethylene carbonate were mixed and the pH was adjusted to 10 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 193g of intermediate was obtained, with a yield of 93%.
[0032] 20.8g of intermediate one was mixed with 24g of vinyl sulfite, the pH was adjusted to 4 with acetic acid, and acetic acid-sodium acetate was added for auxiliary adjustment. The temperature was raised to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product, and the ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 27g of finished product with a purity of 99.4% and a yield of 90%.
[0033] Example 5: 182g of sweet alcohol and 88g of ethylene carbonate were mixed and the pH was adjusted to 10 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sweet alcohol and ethylene glycol were washed away with water. After thorough drying, 193g of intermediate was obtained, with a yield of 93%.
[0034] 41.6g of intermediate one was mixed with 21.6g of vinyl sulfite, the pH was adjusted to 5 with acetic acid, and acetic acid-sodium acetate was added for auxiliary adjustment. The temperature was raised to 90℃ for the second transesterification. After the second transesterification was completed, ethyl acetate was added to dissolve the product, and the ethylene glycol residue was washed away with water. After thorough drying, 45.2g of intermediate two was obtained, with a yield of 89%.
[0035] 25.4g of intermediate II was mixed with 13.6g of vinyl sulfate. The pH was adjusted to 7 with acetic acid and sodium bicarbonate. 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The temperature was raised to 90℃ for the third transesterification step. After the third transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 27g of the final product with a purity of 99.5% and a yield of 85%.
[0036] Example 6: 182g of mannitol and 216g of vinyl sulfite were mixed, and the pH was adjusted to 4 with acetic acid. Sodium acetate was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 247g of intermediate was obtained, with a yield of 90%.
[0037] 27.4g of intermediate one was mixed with 13.6g of vinyl sulfate. The pH was adjusted to 7 with acetic acid and sodium bicarbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The mixture was heated to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was then purified by recrystallization with dimethyl carbonate to obtain 29.6g of the final product with a purity of 99.6% and a yield of 88%.
[0038] Example 7: 182g of mannitol and 108g of vinyl sulfite were mixed and the pH was adjusted to 4 with acetic acid. Sodium acetate was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 198g of intermediate was obtained, with a yield of 87%.
[0039] 22.8g of intermediate one was mixed with 27.3g of vinyl sulfate. The pH was adjusted to 7 with acetic acid and sodium bicarbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The mixture was heated to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was then purified by recrystallization with dimethyl carbonate to obtain 31g of the final product with a purity of 99.5% and a yield of 89%.
[0040] Example 8: 182g of mannitol and 216g of vinyl sulfite were mixed and the pH was adjusted to 5 with acetic acid. Sodium acetate was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 241g of intermediate was obtained, with a yield of 88%.
[0041] 27.4g of intermediate one was mixed with 9.7g of ethylene carbonate, the pH was adjusted to 9 with sodium bicarbonate, and tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product, and the ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 27g of the finished product with a purity of 99.4% and a yield of 90%.
[0042] Example 9: 182g of mannitol and 108g of vinyl sulfite were mixed and the pH was adjusted to 4 with acetic acid. Acetic acid-sodium acetate was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Mannitol and ethylene glycol were washed away with water. After thorough drying, 198g of intermediate was obtained, with a yield of 87%.
[0043] 22.8 g of intermediate one was mixed with 19.4 g of ethylene carbonate. The pH was adjusted to 10 with sodium bicarbonate, and tris(hydroxymethyl)aminomethane was added for further adjustment. The mixture was heated to 90 °C for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 25.8 g of the final product with a purity of 99.4% and a yield of 92%.
[0044] Example 10: 182g of sorbitol and 248g of vinyl sulfate were mixed and the pH was adjusted to 7 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 272g of intermediate was obtained, with a yield of 89%.
[0045] 30.6 g of intermediate one was mixed with 11.9 g of vinylite. The pH was adjusted to 6 with acetic acid and sodium bicarbonate, and 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The mixture was heated to 90 °C for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 30 g of the final product with a purity of 99.3% and a yield of 85%.
[0046] Example 11: 182g of sorbitol and 108g of vinyl sulfite were mixed and the pH was adjusted to 4 with acetic acid. Acetic acid-sodium acetate was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, intermediate 212g was obtained with a yield of 93%.
[0047] 45.6 g of intermediate one was mixed with 24.8 g of vinyl sulfate. The pH was adjusted to 7 with acetic acid and sodium bicarbonate, and 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The mixture was heated to 90 °C for the second transesterification step. After the second transesterification step was completed, ethyl acetate was added to dissolve the product. Ethyl glycol residue was washed away with water, and the mixture was thoroughly dried to obtain 49.9 g of intermediate two, with a yield of 86%.
[0048] 29g of intermediate II was mixed with 9.7g of ethylene carbonate. The pH was adjusted to 8 with sodium bicarbonate, and tris(hydroxymethyl)aminomethane was added for further adjustment. The mixture was heated to 90℃ for the third step of transesterification. After the third step of transesterification was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 27.2g of the final product with a purity of 99.3% and a yield of 86%.
[0049] Example 12: 182g of sorbitol and 409g of vinyl sulfate were mixed, and the pH was adjusted to 7 with acetic acid and sodium bicarbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The mixture was heated to 120°C for transesterification. After transesterification, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 331g of the final product with a purity of 99.6% and a yield of 90%.
[0050] Example 13: 182g of sorbitol and 88g of ethylene carbonate were mixed and the pH was adjusted to 10 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 193g of intermediate was obtained, with a yield of 93%.
[0051] 20.8 g of intermediate one was mixed with 27.3 g of vinyl sulfate. The pH was adjusted to 6.7 with acetic acid and sodium bicarbonate, and 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The mixture was heated to 90 °C for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 28.2 g of the final product with a purity of 99.4% and a yield of 85%.
[0052] Example 14: 182g of sorbitol and 356g of vinyl sulfite were mixed and the pH was adjusted to 4 with acetic acid. Sodium acetate was added to assist in the adjustment. The mixture was heated to 120°C for transesterification. After the transesterification was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 288g of the final product with a purity of 99.3% and a yield of 90%.
[0053] Example 15: 182g of sorbitol and 124g of vinyl sulfate were mixed and the pH was adjusted to 7.3 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 215g of intermediate was obtained, with a yield of 88%.
[0054] 24.4 g of intermediate one was mixed with 19.4 g of ethylene carbonate. The pH was adjusted to 9 with sodium bicarbonate, and tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The mixture was heated to 90 °C for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water, and the product was purified by recrystallization with dimethyl carbonate to obtain 26.3 g of the final product with a purity of 99.6% and a yield of 89%.
[0055] Example 16: 182g of sorbitol and 176g of ethylene carbonate were mixed and the pH was adjusted to 9 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 218g of intermediate was obtained, with a yield of 93%.
[0056] 23.4g of intermediate one was mixed with 11.9g of vinyl sulfite, the pH was adjusted to 5 with acetic acid, and acetic acid-sodium acetate was added for auxiliary adjustment. The temperature was raised to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product, and the ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 24.4g of the finished product with a purity of 99.4% and a yield of 87%.
[0057] Example 17: 182g of sorbitol and 176g of ethylene carbonate were mixed and the pH was adjusted to 10 with sodium carbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The temperature was raised to 120°C for the first step of transesterification. After the first step of transesterification was completed, ethyl acetate was added to dissolve the intermediate. Sorbitol and ethylene glycol were washed away with water. After thorough drying, 215g of intermediate was obtained, with a yield of 92%.
[0058] 23.4g of intermediate one was mixed with 13.6g of vinyl sulfate. The pH was adjusted to 6.5 with acetic acid and sodium bicarbonate. 4-hydroxyethylpiperazine ethanesulfonic acid was added to assist in the adjustment. The temperature was raised to 90℃ for the second transesterification step. After the second transesterification step was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was purified by recrystallization with dimethyl carbonate to obtain 26g of the final product with a purity of 99.6% and a yield of 88%.
[0059] Example 18: 182g of sorbitol and 290g of ethylene carbonate were mixed and the pH was adjusted to 8 with sodium bicarbonate. Tris(hydroxymethyl)aminomethane was added to assist in the adjustment. The mixture was heated to 120°C for transesterification. After the transesterification was completed, dimethyl carbonate was added to dissolve the product. Ethylene glycol residue was washed away with water. The product was then purified by recrystallization with dimethyl carbonate to obtain 242g of the final product with a purity of 99.5% and a yield of 93%.
[0060] The structures of the intermediates and products of Examples 1-18 are shown in the table below.
[0061]
[0062]
[0063]
[0064]
[0065] The advantages of the present invention obtained from the above embodiments are as follows: It provides a method for preparing polycyclic heterocyclic esters. The process route is simple, with few steps, low purification difficulty, and high product purity, which can reach more than 99%, meeting the purity requirements of additives for lithium-ion battery electrolytes.
Claims
1. A method for preparing a polycyclic heterocyclic ester, characterized in that: The transesterification is performed using a hexahydrol and an ester; the ester is selected from one, two, or three of ethylene carbonate, ethylene sulfite, and ethylene sulfate. One ester was selected for a one-step transesterification reaction, with a molar ratio of ester to hexahydrol of 3.3:
1. When two esters are selected, a two-step transesterification reaction is carried out. In the first transesterification reaction, the molar ratio of ester to hexahydrol is 2.0:1, and in the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 1.1:1; or in the first transesterification reaction, the molar ratio of ester to hexahydrol is 1:1, and in the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 2.2:
1. When three esters are selected, a three-step transesterification reaction is carried out. In the first transesterification reaction, the molar ratio of ester to hexahydrol is 1:
1. In the second transesterification reaction, the molar ratio of ester to intermediate obtained in the first step is 1:
1. In the third transesterification reaction, the molar ratio of ester to intermediate obtained in the second step is 1.1:
1.
2. The method for preparing a polycyclic heterocyclic ester according to claim 1, characterized in that: When using ethylene carbonate in a transesterification reaction, the pH of the reaction system should be adjusted to 8-10, and the reaction should be heated to 70-120℃.
3. The method for preparing a polycyclic heterocyclic ester according to claim 1, characterized in that: When using vinyl sulfite in the transesterification reaction, the pH of the reaction system should be adjusted to 4-6, and the reaction should be heated to 70-120℃.
4. The method for preparing a polycyclic heterocyclic ester according to claim 1, characterized in that: When using vinyl sulfate in the transesterification reaction, the pH of the reaction system should be adjusted to 6.5-7.5, and the reaction should be heated to 70-120℃.
5. A method for preparing a polycyclic heterocyclic ester according to claim 2, 3, or 4, characterized in that: The pH of the reaction system is adjusted using one or more of the following: citric acid, acetic acid, sodium carbonate, and sodium bicarbonate.
6. The method for preparing a polycyclic heterocyclic ester according to claim 5, characterized in that: A buffer is added to the reaction system to maintain the pH. The buffer is selected from one or more of 3-morpholine propanesulfonic acid, tris(hydroxymethyl)aminomethane, 4-hydroxyethylpiperazine ethanesulfonic acid, and acetic acid-sodium acetate.