CN114262285B - Method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide - Google Patents
Method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide Download PDFInfo
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Abstract
The invention discloses a method for preparing 4-aminotoluene-3-sulfonic acid by sulfur trioxide, which comprises the steps of dropwise adding a sulfur trioxide solution into a p-toluidine solution for sulfonation reaction to obtain 4-aminotoluene-3-sulfonic acid; the sulfur trioxide solution is obtained by dissolving sulfur trioxide in an organic solvent. According to the invention, the organic solvent is adopted to dilute the sulfur trioxide, and a dripping mode is adopted, so that side reactions such as polymerization, excessive sulfonation and the like of the sulfur trioxide are greatly inhibited, the viscosity of a reaction system is reduced, and meanwhile, the sulfur trioxide can be prevented from being solidified under a low-temperature condition; therefore, the method realizes that sulfur trioxide is directly introduced as a sulfonating agent in the preparation process of 4-aminotoluene-3-sulfonic acid, water is not generated in sulfonation reaction, the dosage of the sulfur trioxide is close to the theoretical quantity, the reaction temperature is mild, the energy consumption is low, the use of a large amount of high-boiling point solvent is avoided, the reaction solvent can be continuously used, and the method has the advantages of rapid reaction, small equipment, less three wastes, economy and rationality.
Description
Technical Field
The invention relates to a preparation method of a pigment intermediate, in particular to a method for preparing 4-aminotoluene-3-sulfonic acid (4B acid) by sulfur trioxide.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
The 4B acid is a white or beige powdery crystal. 4B acid can be diazotized with nitrite in dilute acid, has general amine general property, and is an important intermediate for synthesizing various pigments and reactive dyes. Is widely used for coloring paint, coating, color ink, rubber, plastics and the like.
In recent years, the demands for PR57 pigment and 4B acid products in China have increased significantly due to the sequential shut down, transfer or shift of foreign pigment and intermediate production plants, especially in developed world countries, which have a sequential shut down of parts of the production facility due to pollution problems. At present, the domestic production scale is smaller, the technology is relatively lower, and the continuous production of a 4B acid newly-built and an extension device still exists, so that the production capacity of the 4B acid is excessively increased, the investment of enterprises in process technology research and equipment improvement is relatively insufficient, and the method is limited to meeting the existing equipment and technology. Generally, the production of 4B acid in China has the defects of low yield, troublesome separation operation, more control points, great difference between production batches and serious three wastes.
The method for synthesizing the 4B acid mainly comprises a concentrated sulfuric acid salification rearrangement method (a direct baking method and a solvent method), a fuming sulfuric acid method and the like. In patent CN 101747236A, stirring at 210-220 ℃ for 2-5 hours, and alkali dissolution, decoloration and acid precipitation are also needed for the crude product. The inventor researches find that the process is comparatively backward, the operation condition is worse, the safety is low, the environmental pollution is serious, the product yield is low, and the product also needs to be refined and post-treated. In the patent CN 102718687A, p-toluidine and concentrated sulfuric acid are adopted in a sulfonation reaction kettle, heat conduction oil is introduced into the kettle, and the sulfonation reaction is carried out after the conduction oil is heated to 180 ℃, and the process also needs to carry out alkali dissolution, decoloration and acid precipitation. The inventor researches and discovers that the process is complex in operation, the product yield is not clear, the three wastes in the post-treatment process are large, and certain iso 4B acid is generated. In patent CN 101143841A, p-toluidine is dissolved in an organic solvent, concentrated sulfuric acid is added under stirring, and then the temperature is raised to 180-190 ℃ for sulfonation reaction. In the reaction process, water generated by the reaction is continuously distilled off, and the solvent is recovered by reduced pressure distillation after the reaction. The inventor researches find that the process uses concentrated sulfuric acid as a sulfonating agent, uses a high-boiling point solvent, has high energy consumption and needs to purify a product. Patent DE3401572 reports the preparation of 4B acid by sulfonation with fuming sulfuric acid at 65 ℃. The inventor researches and discovers that the process needs more sulfuric acid and has high raw material cost.
In the existing synthesis method, sulfuric acid is used as a sulfonating agent, and the method is produced by a solvent method or a baking method, and has high reaction temperature or needs to use a high-boiling-point solvent. The reaction process needs dehydration and transposition, and the product 4B acid crude product needs decoloring, filtering, acidification, dehydration, drying and other procedures to obtain the high-purity 4B acid. Certain tar or oxide exists in the reaction process or the purification process, so that amino is easy to oxidize, the product is yellow, and the quality of the product is influenced.
In summary, the traditional 4B acid production process mainly adopts a sulfuric acid or fuming sulfuric acid sulfonation method, and has the problems of large resource consumption, more side reactions, large three wastes and the like, so that the whole process is uneconomical and not environment-friendly.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide, which solves the problems of high production cost, large danger coefficient, low product quality, large three wastes and the like in the traditional production process.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a method for preparing 4-aminotoluene-3-sulfonic acid by sulfur trioxide is characterized in that sulfur trioxide solution is dropwise added into p-toluidine solution for sulfonation reaction to obtain 4-aminotoluene-3-sulfonic acid; the sulfur trioxide solution is obtained by dissolving sulfur trioxide in an organic solvent.
Although sulfur trioxide is an excellent sulfonating agent, in the production process of 4B acid, there is no precedent for preparing 4B acid by sulfonation of sulfur trioxide because of the difficulties of feeding difficulty caused by introducing sulfur trioxide, high system viscosity, side reaction initiation of sulfur trioxide and the like.
In order to solve the problems of difficult feeding, high system viscosity, side reaction caused by sulfur trioxide addition and the like, the method adopts an organic solvent to dilute the sulfur trioxide, adopts a dripping mode, greatly inhibits the side reaction such as polymerization, excessive sulfonation and the like of the sulfur trioxide, and reduces the viscosity of a reaction system. And at the same time, sulfur trioxide can be prevented from solidifying under low temperature conditions.
When the solvent of the sulfonation reaction system is one of dichloroethane, dichloromethane, tetrachloroethane and petroleum ether, the solubility of the raw materials and the product in the solvent is different, wherein the raw materials have high solubility, the product is slightly soluble or even insoluble, and the separation of the product can be realized by simple filtration.
The sulfonation reaction temperature is 0-70 ℃, 4B acid can be generated, the reaction rate is slower when the temperature is lower, the corresponding reaction time is longer, and the reaction selectivity is higher; when the reaction temperature is higher, the reaction rate is accelerated, the reaction time is shortened, and the selectivity of the product is reduced to a certain extent.
The beneficial effects of the invention are as follows:
(1) The method selects the solution of sulfur trioxide/organic solvent as the sulfonating reagent, and has the main advantages of directly generating sulfonic acid groups, generating no water, having the dosage close to the theoretical amount, having short reaction period, less three wastes, economy and environmental protection.
(2) Because the sulfur trioxide has extremely strong electrophilic substitution capability, particularly for the p-toluidine raw material, the reaction activity of the sulfur trioxide on the ortho position of the amino group is very high, and the product yield can reach more than 98 percent and the product purity can reach 98.5 percent only by adopting a raw material proportion of lower temperature and approximately 1 equivalent. Compared with the existing sulfuric acid sulfonation technology, the reaction temperature is mild, and the energy consumption is greatly reduced; the product 4B acid is insoluble or slightly soluble in the organic solvent selected by the invention, the reaction liquid is directly filtered to obtain the product, and the filtrate can be applied to sulfonation reaction without treatment, so that the continuous application of the reaction solvent can be realized, the environmental pollution is reduced, and the production cost is reduced.
(3) In order to realize accurate feeding of sulfur trioxide, the invention dissolves the liquid sulfur trioxide in the organic solvent, prevents the liquid sulfur trioxide from solidifying under the low-temperature condition, and is favorable for realizing pipeline transportation and accurate pumping. In addition, as the sulfur trioxide is diluted by the organic solvent and is slowly dripped, side reactions such as polymerization, excessive sulfonation and the like of the sulfur trioxide are greatly inhibited, and the viscosity of a reaction system is reduced.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a nuclear magnetic spectrum of 4B acid prepared in example 1 of the present invention;
FIG. 2 is a liquid chromatography chart of 4B acid prepared in example 1 of the present invention.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
In view of the problems of large resource consumption, more side reactions, large three wastes and the like in the traditional 4B acid production process, the invention provides a method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide.
In an exemplary embodiment of the invention, a method for preparing 4-aminotoluene-3-sulfonic acid by sulfur trioxide is provided, and a sulfur trioxide solution is dropwise added into a p-toluidine solution for sulfonation reaction to obtain 4-aminotoluene-3-sulfonic acid; the sulfur trioxide solution is obtained by dissolving sulfur trioxide in an organic solvent.
According to the invention, the sulfur trioxide is diluted by adopting an organic solvent, and the side reactions such as polymerization, excessive sulfonation and the like of the sulfur trioxide are greatly inhibited by adopting a dropwise adding mode, and the viscosity of a reaction system is reduced. And at the same time, sulfur trioxide can be prevented from solidifying under low temperature conditions.
In some examples of this embodiment, the sulfonation reaction system solvent is dichloroethane, methylene chloride, tetrachloroethane, or petroleum ether. When these solvents are selected, the solubility of the raw materials and the products in the solvents are different, and the separation of the products can be realized by simple filtration. When the solvent of the sulfonation reaction system is dichloroethane or dichloromethane, the product can be better separated.
In some examples of this embodiment, the temperature of the sulfonation reaction is from 0 to 70 ℃. The reaction temperature can ensure that the obtained main product is 4B acid, the reaction rate is slower when the temperature is lower, the corresponding reaction time is longer, and the reaction selectivity is higher; when the reaction temperature is higher, the reaction rate is accelerated, the reaction time is shortened, and the selectivity of the product is reduced to a certain extent. When the temperature of the sulfonation reaction is 30-60 ℃, the selectivity of the reaction can be ensured, and the reaction rate can be ensured.
In some examples of this embodiment, the temperature of the system is maintained at the temperature of the sulfonation reaction during the dropwise addition of the sulfur trioxide solution. Ensures that sulfonation reaction is carried out in the process of dropwise adding the sulfur trioxide solution, greatly inhibits side reactions such as polymerization and excessive sulfonation of the sulfur trioxide, and reduces the viscosity of a reaction system. Ensure the reaction.
In some examples of this embodiment, the time for the dropwise addition of the sulfur trioxide solution is 2 to 6 hours. The sulfur trioxide solution is slowly dripped, so that the completely reacted sulfur trioxide in the reaction system can be ensured, and the side reactions such as polymerization and excessive sulfonation of the sulfur trioxide can be further inhibited. When the time for dropwise adding the sulfur trioxide solution is 3-5 hours, the effect is better.
In some examples of this embodiment, the reaction was continued for 1 to 3 hours after the dropwise addition. Can ensure the complete sulfonation reaction.
In some examples of this embodiment, the molar ratio of sulfur trioxide to para-toluidine is from 0.95 to 1.2:1. Can ensure complete material reaction. When the molar ratio of the sulfur trioxide to the p-toluidine is 1-1.1:1, the complete reaction of the p-toluidine can be ensured.
In some examples of this embodiment, the mass ratio of the para-toluidine to the organic solvent in the para-toluidine solution is 1:2-5.
In some examples of this embodiment, the mass ratio of sulfur trioxide to organic solvent is 1:2-5.
In some examples of this embodiment, the steps include:
adding p-toluidine into an organic solvent to prepare a p-toluidine solution by dissolution;
adding sulfur trioxide into an organic solvent to dissolve to prepare a sulfur trioxide solution;
heating the p-toluidine solution to the sulfonation reaction temperature, dropwise adding the sulfur trioxide solution, continuing the sulfonation reaction after the dropwise adding, cooling and filtering after the sulfonation reaction is finished to obtain the 4-aminotoluene-3-sulfonic acid.
In order to enable those skilled in the art to more clearly understand the technical scheme of the present invention, the technical scheme of the present invention will be described in detail with reference to specific embodiments.
Example 1
21.4g of p-toluidine was dissolved in 42.8g of dichloroethane, stirred well until the p-toluidine was completely dissolved, then added to a three-necked flask with stirring, and heated slowly to 30 ℃. 16g of sulfur trioxide is dissolved in 42.8g of dichloroethane, and after the temperature in the reaction flask reaches the set temperature, the sulfur trioxide solution is slowly added dropwise to the p-toluidine solution for 3 hours. After the completion of the sulfur trioxide dropwise addition, the reaction was continued for 1 hour, and 37.13g of 4B acid was obtained by cooling and filtration, with a yield of 99.2% and a purity of 99.5%, as shown in FIGS. 1 to 2.
The result data in fig. 2 are shown in the following table.
Table liquid chromatography data
Example 2
32.1g of p-toluidine is dissolved in 100g of tetrachloroethane, and the mixture is stirred fully until the p-toluidine is completely dissolved, and then the mixture is added into a three-neck flask with stirring, and the temperature of the system is controlled to be 0 ℃. 25.2g of sulfur trioxide is dissolved in 100g of tetrachloroethane, and after the temperature in a reaction bottle reaches a set temperature, the sulfur trioxide solution is slowly added into the p-toluidine solution dropwise for 6h. After the addition of sulfur trioxide is finished, the reaction is continued for 3 hours, and 55.48g of 4B acid is obtained through cooling and filtering, the yield is 98.8%, and the purity is 99.2%.
Example 3
21.4g of p-toluidine was dissolved in 100g of methylene chloride, stirred well until the p-toluidine was completely dissolved, then added to a three-necked flask with stirring, and heated slowly to 60 ℃. 17.6g of sulfur trioxide is dissolved in 100g of methylene dichloride, and after the temperature in a reaction bottle reaches a set temperature, the sulfur trioxide solution is slowly added into the p-toluidine solution dropwise for 5h. After the addition of sulfur trioxide is completed, the reaction is continued for 2 hours, and the 4B acid 37.10g is obtained through cooling and filtering, wherein the yield is 99.1%, and the purity is 99.6%.
Example 4
21.4g of p-toluidine is dissolved in 107g of petroleum ether, fully stirred until the p-toluidine is completely dissolved, then added into a three-neck flask with stirring, and slowly heated to 50 ℃. 15.2g of sulfur trioxide is dissolved in 107g of petroleum ether, and after the temperature in the reaction bottle reaches the set temperature, the sulfur trioxide solution is slowly added into the p-toluidine solution for 3 hours. After the addition of sulfur trioxide is finished, the reaction is continued for 2 hours, and 37.02g of 4B acid is obtained through cooling and filtering, the yield is 98.9%, and the purity is 99.0%.
Example 5
21.4g of p-toluidine is dissolved in 100g of dichloroethane mother liquor, fully stirred until the p-toluidine is completely dissolved, then added into a three-neck flask with stirring, and slowly heated to 70 ℃. 19.2g of sulfur trioxide is dissolved in 100g of dichloroethane mother liquor, and after the temperature in the reaction flask reaches the set temperature, the sulfur trioxide solution is slowly added into the p-toluidine solution dropwise for 2h. After the addition of sulfur trioxide is completed, the reaction is continued for 1 hour, and the reaction is cooled and filtered to obtain 37.0g of 4B acid, wherein the yield is 98.8%, and the purity is 99.1%.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for preparing 4-aminotoluene-3-sulfonic acid by sulfur trioxide is characterized in that a sulfur trioxide solution is dropwise added into a p-toluidine solution for sulfonation reaction to obtain 4-aminotoluene-3-sulfonic acid; the sulfur trioxide solution is obtained by dissolving sulfur trioxide in an organic solvent;
the method comprises the following specific steps:
adding p-toluidine into an organic solvent to prepare a p-toluidine solution by dissolution;
adding sulfur trioxide into an organic solvent to dissolve to prepare a sulfur trioxide solution;
heating p-toluidine solution to sulfonation reaction temperature, dropwise adding sulfur trioxide solution, continuing sulfonation reaction after dropwise adding, cooling and filtering after sulfonation reaction is finished to obtain 4-aminotoluene-3-sulfonic acid;
the temperature of sulfonation reaction is 0-70 ℃;
the time for dropwise adding the sulfur trioxide solution is 2-6 hours;
the solvent of the sulfonation reaction system is dichloroethane, dichloromethane and tetrachloroethane;
the method comprises the steps of dissolving liquid sulfur trioxide in an organic solvent, adopting a slow dropwise adding mode, inhibiting polymerization of the sulfur trioxide and excessive sulfonation side reaction, reducing the viscosity of a reaction system, preventing the reaction system from solidifying under a low-temperature condition, and being beneficial to realizing pipeline transportation and accurate pumping.
2. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide as claimed in claim 1, wherein the solvent of the sulfonation reaction system is dichloroethane or dichloromethane.
3. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the temperature of the sulfonation reaction is 30 to 60 ℃.
4. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide as claimed in claim 1, wherein the temperature of the system is maintained at the temperature of sulfonation reaction during the dropping of the sulfur trioxide solution.
5. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the time for dropping the sulfur trioxide solution is 3 to 5 hours.
6. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the reaction is continued for 1 to 3 hours after the dropping.
7. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the molar ratio of sulfur trioxide to p-toluidine is 0.95-1.2:1.
8. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide as set forth in claim 7, wherein the molar ratio of sulfur trioxide to p-toluidine is 1 to 1.1:1.
9. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the mass ratio of para-toluidine to organic solvent in the para-toluidine solution is 1:2-5.
10. The method for preparing 4-aminotoluene-3-sulfonic acid from sulfur trioxide according to claim 1, characterized in that the mass ratio of sulfur trioxide to organic solvent is 1:2-5.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE3401572A1 (en) * | 1984-01-18 | 1985-07-25 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING P-TOLUIDINE-2-SULPHONIC ACID |
| CN101143841B (en) * | 2007-10-08 | 2010-09-22 | 镇江市丹徒区天龙化工有限公司 | Method for producing 4-aminotoluene-3-sulfonic acid |
| CN108675946A (en) * | 2018-06-21 | 2018-10-19 | 中北大学 | A method of preparing 2,4- diamino benzene sulfonic acids |
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