CN114213274B - Synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester - Google Patents
Synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester Download PDFInfo
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- CN114213274B CN114213274B CN202111434388.2A CN202111434388A CN114213274B CN 114213274 B CN114213274 B CN 114213274B CN 202111434388 A CN202111434388 A CN 202111434388A CN 114213274 B CN114213274 B CN 114213274B
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Abstract
The invention discloses a synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester, which comprises the following steps: (1) Mixing oxalic acid and ethanol, heating, and adding excessive absolute ethanol and solid acid catalyst to obtain a reaction material; (2) Continuously dripping absolute ethyl alcohol into the reaction material, distilling and cooling to obtain a rectifying material; (3) mixing ethanol and L-alanine to obtain a mixed material; (4) Mixing the mixed material with the rectifying material, adding absolute ethyl alcohol and benzene, and heating, dehydrating and esterifying to obtain a reaction liquid; and (3) heating the reaction solution, recovering a mixture of benzene and ethanol at normal pressure, filtering the mixture while the mixture is hot, distilling the filtrate under reduced pressure to recover excessive diethyl oxalate to obtain a concentrated solution, and cooling and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester. According to the synthesis process of the N-ethoxyoxalyl-L-alanine ethyl ester, provided by the invention, the acidity in the reaction is stable by adding the solid acid catalyst, the forward reaction is ensured, and the reaction rate is effectively improved.
Description
Technical Field
The invention relates to the technical field of vitamin B6 synthesis, in particular to a synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester.
Background
Vitamin B6 is one of vitamins necessary for human body, is a constituent of certain coenzymes in the human body, participates in various metabolic reactions of the human body, particularly has close relation with the metabolism of amino acids, and at present, the vitamin B6 on the market is mainly sold in the form of pyridoxine hydrochloride, and is generally produced by a chemical synthesis method in industry. Most of the existing vitamin B6 synthesis methods are an oxazole method, namely, 4-methyl-5-ethoxy oxazole is used as a raw material to synthesize the vitamin B6, and N-ethoxyoxalyl-L-alanine ethyl ester is used as a main raw material for industrial synthesis of 4-methyl-5-ethoxy oxazole. In the traditional process, the N-ethoxyoxalyl-L-alanine ethyl ester is prepared from diethyl oxalate, oxalic acid and alanine, the diethyl oxalate has certain toxicity, the diethyl oxalate is directly used as the raw material and needs to be stored and transported according to the relevant regulations of toxic chemicals, meanwhile, the adding amount of the diethyl oxalate needs to be continuously regulated and controlled in the production process to ensure the forward synthesis reaction, so that the existing N-ethoxyoxalyl-L-alanine ethyl ester synthesis process is complicated in steps, high in cost, unfavorable for the control of the synthesis reaction, and the production cost of enterprises is increased.
Disclosure of Invention
In view of the above, the present invention provides a synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester for solving the above problems.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a synthesis process of N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps of:
Further, the synthesis process of the N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps:
(1) Mixing oxalic acid and ethanol, heating to 90-105 ℃, adding excessive absolute ethanol and solid acid catalyst, controlling the reaction temperature to 90-120 ℃, and preserving heat for 1-2 h to obtain a reaction material;
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the ethyl alcohol is equal to the azeotropic speed of alcohol water, distilling an alcohol water azeotrope, and cooling to 70-80 ℃ to obtain a rectification material;
(3) Mixing ethanol and L-alanine, heating to 80-85 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material;
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), adding absolute ethyl alcohol and benzene, heating to 80-100 ℃ for dehydration and esterification to obtain a reaction liquid;
(5) And (3) heating the reaction solution in the step (4) to 140-150 ℃, recovering the mixture of benzene and ethanol and the solid acid catalyst at normal pressure, filtering while the mixture is hot, distilling the filtrate under reduced pressure to recover excessive diethyl oxalate to obtain a concentrated solution, cooling the concentrated solution to 60-80 ℃, and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester.
Further, the mass ratio of the ethanol to the oxalic acid in the step (1) is 0.2-0.4:1, and the ethanol concentration in the step (1) and the step (3) is 80-100%.
Further, the solid acid catalyst in the step (1) is at least one of aluminum-based solid acid, carbon-based solid acid and sulfonic acid-type solid acid.
Further, the content of diethyl oxalate in the rectifying material in the step (2) is 85-95%.
Further, in the step (3), the mass ratio of the ethanol to the L-alanine is 7-9:10.
Further, in the step (4), the mass ratio of the mixed material to the rectifying material is 4.8-5:6, and the mass ratio of the absolute ethyl alcohol to the benzene to the mixed material is 7:8:18.
Further, the moisture content in the reaction liquid in the step (4) is less than 0.1%.
Further, the conditions of the reduced pressure distillation in the step (5) are that the temperature is 150 ℃ and the pressure is-0.098 MPa.
Further, the concentration of the N-ethoxyoxalyl-L-alanine ethyl ester in the step (5) is 95-99%.
The preparation method of the N-ethoxyoxalyl-L-alanine ethyl ester has the beneficial effects that the ratio of
According to the invention, ethanol, oxalic acid and L-alanine are used as raw materials, benzene is used as a water carrying agent to prepare N-ethoxyoxalyl-L-alanine ethyl ester, diethyl oxalate is generated through esterification reaction of ethanol and oxalic acid, and absolute ethanol is added to form an azeotrope with water generated by the reaction, and the boiling point of the azeotrope formed by the ethanol and the water is lower than that of the diethyl oxalate, so that water generated by the reaction can be carried out through distillation of the azeotrope, the reaction is carried out forward, and the content of the diethyl oxalate in the reactant is improved; meanwhile, benzene is added in the reaction of diethyl oxalate and L-alanine, and can form a ternary azeotrope with ethanol and water, so that the water removal rate is further improved, the forward reaction of diethyl oxalate and L-alanine is ensured, and the benzene-alcohol mixture can be recycled after water is removed; meanwhile, the solid acid catalyst is adopted to ensure the stability of acidity during the reaction, so that acid is not required to be added into a reaction system, the operation steps of the reaction are simplified, the reaction rate of diethyl oxalate and L-alanine can be improved by controlling the addition amount of the L-alanine, and the production efficiency is improved while the cost can be effectively controlled.
Drawings
FIG. 1 shows the reaction equation of N-ethoxyoxalyl-L-alanine ethyl ester according to the present invention.
Detailed Description
For a further understanding of the present invention, reference will now be made in detail to the present invention, examples of which are illustrated in the accompanying drawings and described in the specification.
The invention provides a method for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester, which is used for synthesizing an intermediate N-ethoxyoxalyl-L-alanine ethyl ester of vitamin B 6, and comprises the following steps:
(1) Mixing oxalic acid and ethanol according to the mass ratio of the ethanol with the concentration of 80-100% to oxalic acid of 0.2-0.4:1, heating to 90-105 ℃, adding excessive absolute ethanol and solid acid catalyst, controlling the reaction temperature to 90-120 ℃, and preserving heat for 1-2 hours to obtain a reaction material.
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the absolute ethyl alcohol is equal to the azeotropic speed of alcohol and water, distilling the alcohol and water azeotrope, and cooling to 70-80 ℃ to obtain a rectification material containing 85-95% diethyl oxalate.
(3) Mixing ethanol and L-alanine according to the mass ratio of the ethanol with the concentration of 80-100% to the L-alanine of 7-9:10, heating to 80-85 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material.
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), wherein the mass ratio of the mixed material to the rectifying material is 4.8-5:6, adding absolute ethyl alcohol and benzene, and the mass ratio of the absolute ethyl alcohol to the benzene to the mixed material is 7:8:18, heating to 80-100 ℃ for dehydration and esterification, thus obtaining a reaction liquid with the moisture content less than 0.1%.
(5) Heating the reaction solution in the step (4) to 140-150 ℃, recovering the mixture of benzene and ethanol and the solid acid catalyst under normal pressure, filtering while the mixture is hot, recovering excessive diethyl oxalate through reduced pressure distillation of the filtrate under the conditions of the temperature of 150 ℃ and the pressure of-0.098 MPa, obtaining concentrated solution, cooling the concentrated solution to 60-80 ℃, and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester with the concentration of 95-99%.
The solid acid catalyst in the step (1) is at least one of aluminum-based solid acid, carbon-based solid acid and sulfonic acid-type solid acid.
Example 1
The synthetic method of the N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps:
(1) Mixing oxalic acid and ethanol according to the mass ratio of the ethanol with the concentration of 80% to oxalic acid of 0.2:1, heating to 90 ℃, adding excessive absolute ethanol and aluminum-based solid acid, controlling the reaction temperature to 90 ℃, and preserving heat for 1h to obtain a reaction material.
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the absolute ethyl alcohol is equal to the azeotropic speed of alcohol and water, distilling the alcohol and water azeotrope, and cooling to 70 ℃ to obtain a rectification material containing diethyl oxalate.
(3) Mixing ethanol and L-alanine according to the mass ratio of the ethanol with the concentration of 80% to the L-alanine of 7:10, heating to 80 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material.
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), wherein the mass ratio of the mixed material to the rectifying material is 4.8:6, adding absolute ethyl alcohol and benzene, and heating to 80 ℃ for dehydration and esterification, so as to obtain a reaction liquid with the water content of less than 0.1 percent.
(5) Heating the reaction solution in the step (4) to 140 ℃, recovering the mixture of benzene and ethanol and aluminum-based solid acid at normal pressure, filtering while the mixture is hot, recovering excessive diethyl oxalate through reduced pressure distillation of the filtrate under the conditions of the temperature of 150 ℃ and the pressure of-0.098 MPa, obtaining a concentrated solution, cooling the concentrated solution to 60 ℃, and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester.
Example two
The synthetic method of the N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps:
(1) Mixing oxalic acid and ethanol according to the mass ratio of ethanol with the concentration of 90% to oxalic acid of 0.3:1, heating to 100 ℃, adding excessive anhydrous ethanol and carbon-based solid acid, controlling the reaction temperature to 105 ℃, and preserving heat for 1.5h to obtain a reaction material.
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the absolute ethyl alcohol is equal to the azeotropic speed of alcohol and water, distilling the alcohol and water azeotrope, and cooling to 75 ℃ to obtain a rectification material containing diethyl oxalate.
(3) Mixing ethanol and L-alanine according to the mass ratio of ethanol to L-alanine of 90% of the concentration of 8:10, heating to 83 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material.
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), wherein the mass ratio of the mixed material to the rectifying material is 4.9:6, adding absolute ethyl alcohol and benzene, and heating to 90 ℃ for dehydration and esterification, so as to obtain a reaction liquid with the water content of less than 0.1 percent.
(5) Heating the reaction solution in the step (4) to 145 ℃, recovering the mixture of benzene and ethanol and carbon-based solid acid under normal pressure, filtering while the mixture is hot, recovering excessive diethyl oxalate through reduced pressure distillation of the filtrate under the conditions of the temperature of 150 ℃ and the pressure of-0.098 MPa, obtaining a concentrated solution, cooling the concentrated solution to 70 ℃, and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester.
Example III
The synthetic method of the N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps:
(1) Mixing oxalic acid and ethanol according to the mass ratio of 100% ethanol to oxalic acid of 0.4:1, heating to 105 ℃, adding excessive absolute ethanol and sulfonic acid type solid acid, controlling the reaction temperature to 120 ℃, and preserving heat for 2 hours to obtain a reaction material.
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the absolute ethyl alcohol is equal to the azeotropic speed of alcohol and water, distilling the alcohol and water azeotrope, and cooling to 80 ℃ to obtain a rectification material containing diethyl oxalate.
(3) Mixing ethanol and L-alanine according to the mass ratio of ethanol to L-alanine of 100% of the concentration of 9:10, heating to 85 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material.
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), wherein the mass ratio of the mixed material to the rectifying material is 5:6, adding absolute ethyl alcohol and benzene, and the mass ratio of the absolute ethyl alcohol to the benzene to the mixed material is 7:8:18, and heating to 100 ℃ for dehydration and esterification to obtain a reaction liquid with the moisture content of less than 0.1%.
(5) Heating the reaction solution in the step (4) to 150 ℃, recovering the mixture of benzene and ethanol and the sulfonic acid type solid acid under normal pressure, filtering while the mixture is hot, recovering excessive diethyl oxalate through reduced pressure distillation under the conditions of the temperature of 150 ℃ and the pressure of-0.098 MPa to obtain a concentrated solution, cooling the concentrated solution to 80 ℃, and storing the concentrated solution to obtain the N-ethoxyoxalyl-L-alanine ethyl ester.
Experimental example
The N-ethoxyoxalyl-L-alanine ethyl ester prepared in examples 1 to 3 was detected, and the concentration of diethyl oxalate, the concentration and the yield of N-ethoxyoxalyl-L-alanine ethyl ester were measured, and the yield was calculated based on the L-alanine feed amount. The specific measurement results are shown in Table 1:
Table 1: concentration and yield of N-ethoxyoxalyl-L-alanine ethyl ester
| Detecting items | Example 1 | Example 2 | Example 3 |
| Concentration of diethyl oxalate/% | 89.8 | 94.6 | 92.7 |
| N-ethoxyoxalyl-L-alanine ethyl ester concentration/% | 95.4 | 97.1 | 96.2 |
| N-ethoxyoxalyl-L-alanine ethyl ester yield/% | 90.7 | 92.2 | 91.4 |
As can be seen from the measurement results in Table 1, in examples 1 to 3 of the present invention, diethyl oxalate is produced by esterification of ethanol and oxalic acid, and absolute ethanol is added to form an azeotrope with water produced by the reaction, and the boiling point of the azeotrope formed by ethanol and water is lower than that of diethyl oxalate, so that water produced by the reaction can be carried out by distilling the azeotrope, the esterification reaction can be carried out forward, and the concentration of diethyl oxalate produced is more than 85%, so that the content of diethyl oxalate in the reactant can be increased; meanwhile, in the embodiments 1 to 3 of the invention, benzene is added as a water carrying agent in the reaction process of diethyl oxalate and L-alanine, and the benzene, ethanol and water can form a ternary azeotrope, so that the water removal rate is further improved, the forward reaction of diethyl oxalate and L-alanine is ensured, and the benzene-alcohol mixture can be recycled for multiple times after water is removed; meanwhile, the solid acid catalyst is adopted to ensure the stability of acidity during the reaction, so that acid is not required to be added into a reaction system, the operation steps of the reaction are simplified, the reaction rate of diethyl oxalate and L-alanine can be improved by controlling the addition amount of the L-alanine during the reaction, the concentration of the yield of the N-ethoxyoxalyl-L-alanine ethyl ester is ensured to be more than 95%, the yield is ensured to be more than 90%, and the production efficiency is improved while the cost is effectively controlled.
It will be apparent to those skilled in the art from this disclosure that various other changes and modifications can be made which are within the scope of the invention as defined in the appended claims.
Claims (8)
1. The synthesis process of the N-ethoxyoxalyl-L-alanine ethyl ester is characterized in that the reaction equation of the N-ethoxyoxalyl-L-alanine ethyl ester is as follows:
the synthesis process of the N-ethoxyoxalyl-L-alanine ethyl ester comprises the following steps:
(1) Mixing oxalic acid and ethanol, heating to 90-105 ℃, adding excessive absolute ethanol and solid acid catalyst, controlling the reaction temperature to 90-120 ℃, and preserving heat for 1-2 h to obtain a reaction material;
(2) Continuously dropwise adding absolute ethyl alcohol into the reaction material in the step (1), wherein the dropping speed of the ethyl alcohol is equal to the azeotropic speed of alcohol water, distilling an alcohol water azeotrope, and cooling to 70-80 ℃ to obtain a rectification material;
(3) Mixing ethanol and L-alanine, heating to 80-85 ℃, and keeping reflux until the L-alanine is completely dissolved to obtain a mixed material;
(4) Adding the mixed material in the step (3) into the rectifying material in the step (2), adding absolute ethyl alcohol and benzene, heating to 80-100 ℃ for dehydration and esterification to obtain a reaction liquid;
(5) Heating the reaction solution in the step (4) to 140-150 ℃, recovering the mixture of benzene and ethanol and the solid acid catalyst at normal pressure, filtering while the mixture is hot, distilling the filtrate under reduced pressure to recover excessive diethyl oxalate to obtain a concentrated solution, cooling the concentrated solution to 60-80 ℃, and storing the concentrated solution to obtain N-ethoxyoxalyl-L-alanine ethyl ester;
wherein the solid acid catalyst in the step (1) is at least one of aluminum-based solid acid, carbon-based solid acid and sulfonic acid-type solid acid.
2. The process for synthesizing the N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the mass ratio of the ethanol to the oxalic acid in the step (1) is 0.2-0.4:1, and the ethanol concentration in the step (1) and the step (3) is 80-100%.
3. The process for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the content of diethyl oxalate in the rectification material in the step (2) is 85-95%.
4. The process for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the mass ratio of ethanol to L-alanine in the step (3) is 7-9:10.
5. The process for synthesizing the N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the mass ratio of the mixed material to the rectified material in the step (4) is 4.8-5:6, and the mass ratio of the absolute ethyl alcohol to the benzene to the mixed material is 7:8:18.
6. The process for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the moisture content in the reaction liquid of the step (4) is less than 0.1%.
7. The process for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the condition of reduced pressure distillation in the step (5) is that the temperature is 150 ℃ and the pressure is-0.098 MPa.
8. The process for synthesizing N-ethoxyoxalyl-L-alanine ethyl ester according to claim 1, wherein the concentration of N-ethoxyoxalyl-L-alanine ethyl ester in the step (5) is 95 to 99%.
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| CN101830821B (en) * | 2010-05-12 | 2013-09-11 | 浙江工业大学 | Chemical synthesis method of N-alcoxyloxalyl alanine ester |
| CN104725262B (en) * | 2013-12-23 | 2018-05-15 | 大丰海嘉诺药业有限公司 | A kind of continuous method for preparing N- ethyoxyl oxalyl alanine ethyl esters |
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