CN111470963A - Method for preparing phenoxyacetic acid and 2, 4-dichlorophenoxyacetic acid - Google Patents
Method for preparing phenoxyacetic acid and 2, 4-dichlorophenoxyacetic acid Download PDFInfo
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- CN111470963A CN111470963A CN201910043604.7A CN201910043604A CN111470963A CN 111470963 A CN111470963 A CN 111470963A CN 201910043604 A CN201910043604 A CN 201910043604A CN 111470963 A CN111470963 A CN 111470963A
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- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
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- C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
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- C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
- C07C51/363—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by introduction of halogen; by substitution of halogen atoms by other halogen atoms
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- C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
- C07C51/367—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by introduction of functional groups containing oxygen only in singly bound form
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Abstract
An environment-friendly method for preparing phenoxyacetic acid and 2, 4-dichlorophenoxyacetic acid (2.4-D) comprises separating and recovering residual phenol and phenoxyacetic acid in wastewater by nanofiltration membrane separation and resin adsorption process instead of sodium hydroxide through ammonia and potassium hydroxide, and obtaining agricultural ammonium chloride containing potassium chloride or agricultural ammonium sulfate containing potassium chloride as byproduct. The reaction is carried out by using a micro-reactor device, the diameter of a micro-porous membrane of the micro-reactor is 1-10 microns, the channel size of a flow-through phase is 1-10 mm, and the reaction time is 0.1-30 minutes.
Description
Technical Field
The invention relates to a method for preparing phenoxyacetic acid and 2, 4-dichlorophenoxyacetic acid (2.4-D) in an environment-friendly way, belonging to the technical field of chemical production.
Background
Phenoxyacetic acid is an important chemical raw material, and can be used for producing penicillin V, herbicides, dyes, insecticides, bactericides, plant hormones, intermediates of central nervous system stimulants and the like. The penicillin V potassium tablet, the prior domestic phenoxyacetic acid is mainly used for producing penicillin V. Converting phenoxyacetic acid into acyl chloride, and then carrying out condensation reaction with amino at the 6 th position on 6-APA to obtain penicillin V. Penicillin V is a derivative of penicillin G, has the characteristics of good acid resistance, can be orally taken, solves the problem that penicillin needs skin test and pain during injection before injection, and is increasingly widely used clinically.
2, 4-dichlorphenoxyacetic acid (2, 4-D), is a systemic conduction type herbicide widely used, has phytohormone action and weeding selection effect, and can stimulate the growth of plants at lower concentration; at higher concentrations, the plant metabolism process can be destroyed to kill the plant. At present, the herbicide is widely used for preventing and killing weeds in crops such as wheat fields, corns, fruit trees, vegetables and the like. Phenoxyacetic acid is a key intermediate of the etherification-chlorination process. The prior method for preparing phenoxyacetic acid is to directly react sodium chloroacetate with sodium phenoxide at reflux temperature and then carry out acidification to obtain a target product, and chloroacetic acid is easy to generate dechlorination hydrolysis reaction under an alkaline condition to obtain glycolic acid, so that the selectivity and yield of chemical synthesis reaction are reduced, and the consumption of chloroacetic acid is increased.
In 2011, 2, 4-D was sold in the market up to $ 5.8 billion, and was third to glyphosate and paraquat, which are the most common herbicides in the world. With the popularization and application of 2, 4-D resistant transgenic crops, the market prospect of 2, 4-D products is generally seen, and numerous enterprises in China come to the horse or expand 2, 4-D production devices. However, from the published data, the production process used by domestic 2, 4-D product production enterprises has the problem of 'three wastes' treatment, the production of phenoxyacetic acid can generate waste water containing a large amount of sodium chloride, the waste water containing sodium chloride salt is not easy to treat, the recovered by-product sodium chloride has a large impurity content, especially contains phenol organic matters, and cannot be directly used as industrial sodium chloride salt, and a large amount of cost is required for refining.
The prior phenoxyacetic acid production section and the subsequent chlorination section for producing 2, 4-D at home generally adopt a kettle reaction or an intermittent method for production, and the production mode is firstly that the production environment is particularly poor, the body health of workers is influenced, and the requirements of environmental protection are not met. Also, the product yield is low.
Microreactors, i.e. microchannel reactors, are manufactured by means of precision machining techniques and have characteristic dimensions of between 10 and 300 microns (or 1 mm and 10 mm for the channel dimensions of the mobile phase), the "micro" of which means that the channels for the process fluid are in the order of microns and does not mean that the overall dimensions of the microreactor are small or that the yield of product is small. The microreactors can contain millions of microchannels and thus achieve high throughput. The microreactor apparatus can be subdivided into micromixers, micro-heat exchangers and microreactors depending on their main use or function. Due to the internal microstructure, the micro-reactor equipment has extremely large specific surface area which can be hundreds of times or even thousands of times of the specific surface area of the stirring kettle. The micro-reactor has excellent heat transfer and mass transfer capacity, can realize instantaneous uniform mixing of materials and high-efficiency heat transfer, so that a plurality of reactions which cannot be realized in the conventional reactor can be realized in the micro-reactor. At present, microreactors are widely applied to research and development of chemical process, and the application of microreactors in commercial production is increasing day by day. The main application fields of the method comprise an organic synthesis process, preparation of micron and nanometer materials and production of daily chemicals. In chemical production, the latest technology has made it possible to achieve flow rates of up to ten thousand litres per hour.
Disclosure of Invention
The invention provides a method for preparing phenoxyacetic acid and 2, 4-dichlorophenoxyacetic acid (2.4-D) in an environment-friendly way. The method of regulating the pH value of the aqueous solution by introducing ammonia and utilizing potassium hydroxide replaces the traditional process of using sodium hydroxide. The residual phenol and phenoxyacetic acid in the wastewater are separated and recovered by utilizing a nanofiltration membrane separation and resin adsorption process. The waste water is subjected to multi-effect evaporation concentration, temperature reduction crystallization and centrifugation to obtain an agricultural ammonium chloride byproduct containing potassium chloride or an agricultural ammonium sulfate byproduct containing potassium chloride. The microreactor equipment is used for reaction, so that the product yield is improved, and the production environment is improved.
The invention is realized by the following method and steps:
1. adding chloroacetic acid aqueous solution into a continuous or intermittent reactor, slowly introducing ammonia for reaction (or adding ammonium bicarbonate for reaction), and controlling the temperature to be 10-40 ℃ to obtain the chloroacetic ammonium aqueous solution. The mol ratio of the chloroacetic acid to the ammonia is 1: 1-1.1, the mol ratio of the chloroacetic acid to the ammonium bicarbonate is 1: 1-1.1, and the content of the chloroacetic acid in the chloroacetic acid aqueous solution is 30-70%.
2. Adding water and phenol into a condensation reaction kettle with condensation reflux, introducing ammonia for reaction (or adding ammonium bicarbonate for reaction) under the protection of nitrogen, wherein the molar ratio of phenol to ammonia is 1: 1-1.1, and the molar ratio of phenol to ammonium bicarbonate is 1: 1-1.1. The temperature is controlled to be 65-85 ℃, and the weight ratio of phenol to water is 1: 1-3. After the ammonia reaction is finished, adding solid potassium hydroxide or a potassium hydroxide aqueous solution, and adjusting the pH value of the solution to 10-12.
3. And (3) after the condensation reaction kettle in the step (2) is filled with ammonia for reaction, heating to 90-110 ℃, and dropwise adding the ammonium chloroacetate aqueous solution obtained in the step (1). The pH value of the solution is kept to 10-12 by adding solid potassium hydroxide or potassium hydroxide aqueous solution. And after the addition of the ammonium chloroacetate aqueous solution is finished, keeping the temperature and reacting for 10-30 minutes.
4. Step 2 the reaction of phenol with ammonia can also be carried out in a microreactor:
mixing phenol and water solution, heating to 65-85 deg.c, pumping into micro reactor and introducing ammonia for reaction. The molar ratio of phenol to ammonia is 1: 1-1.1, and the weight ratio of phenol to water is 1: 1-3.
The diameter of the microporous membrane selected by the microreactor is 1 micron-10 microns, the channel size of the flow-through phase is 1 mm-10 mm, the reaction time is 0.1-30 minutes, and the reaction temperature is 65-85 ℃. In the present invention, a membrane-dispersed microstructure reactor is preferably selected. The number of microchannel reactors is not particularly limited. When more than 2 microchannel reactors are used, each microchannel reactor is configured in series, and reaction raw materials sequentially enter each microchannel reactor. The structure of the microchannel reactor includes, but is not limited to, a rectangle, a trapezoid, a heart, a double trapezoid, and an irregular shape. In the reaction, the microchannel reactor may be used as different modules as needed, such as a mixing preheating module, a reaction module, a cooling module, and the like. These modules are only functionally distinct and the geometry may be identical.
5. Step 4, adding solid potassium hydroxide or an aqueous solution of potassium hydroxide into the reaction solution obtained by the microreactor, adjusting the pH value of the solution to 10-12, and heating to 60-110 ℃; heating the mixed solution and the ammonium chloroacetate aqueous solution obtained in the step 1 to 60-110 ℃, respectively adding the mixed solution and the ammonium chloroacetate aqueous solution into the microreactor according to the proportion through a pump, introducing a potassium hydroxide aqueous solution, keeping the pH value in the microreactor at 10-12, and reacting for 0.1-30 minutes.
6. Transferring the reaction liquid obtained in the step 3 or the step 5 into an acidification kettle, cooling, dropwise adding hydrochloric acid or sulfuric acid for acidification until the pH value reaches 1-5, cooling to 15-35 ℃, and centrifugally separating to obtain a crude phenoxyacetic acid product.
7. The crude phenoxyacetic acid is prepared by separating water and residual phenol in a melting refining mode under the protection of nitrogen, and condensing and recovering the water and the phenol. The temperature of the melting refining is 100-200 ℃. Obtaining fine phenoxyacetic acid.
8. The aqueous solution centrifuged in step 6 is treated in the following way:
1) firstly, adding a certain amount of water, introducing ammonia (or adding sulfuric acid) to adjust the pH value of the aqueous solution to 6-8, and separating by using a nanofiltration membrane to obtain nanofiltration permeate and nanofiltration retentate;
2) and (3) nanofiltration permeate liquid is firstly adsorbed by adsorption resin to separate residual phenol and phenoxyacetic acid in the aqueous solution, and the phenol and the phenoxyacetic acid are recovered after desorption. And (3) carrying out multi-effect evaporation, cooling crystallization and centrifugation on the nanofiltration permeate liquid subjected to resin adsorption treatment to obtain an ammonium chloride fertilizer raw material containing potassium chloride or an ammonium sulfate fertilizer raw material byproduct containing potassium chloride. The water solution recovered by multi-effect evaporation and condensation is recycled and used for dissolving chloroacetic acid or phenol;
3) nanofiltration trapped fluid is directly used for dissolving chloroacetic acid or phenol and is recycled;
4) the water solution centrifugally separated in the step 4 can also be directly adsorbed by using an adsorption resin, and organic matters in the water solution are separated and recovered through desorption. And adsorbing the treated aqueous solution by resin, and performing multi-effect evaporation, cooling crystallization and centrifugation to obtain an ammonium chloride fertilizer raw material containing potassium chloride or an ammonium sulfate fertilizer raw material byproduct containing potassium chloride. The water solution recovered by multi-effect evaporation and condensation is recycled and used for dissolving chloroacetic acid or phenol;
5) a small amount of residual liquid left after multi-effect evaporation or nanofiltration trapped fluid is treated in a catalytic oxidation mode after impurities are excessively enriched after multiple times of trapping. The catalytic oxidation process comprises the following steps: fenton oxidation (Fenton), photocatalytic oxidation, ozone catalytic oxidation, electrochemical oxidation, ultrasonic oxidation, supercritical water oxidation, wet catalytic oxidation and the like.
9. Preparation of 2, 4-Dichlorophenoxyacetic acid (2, 4-D):
1) adding solvent tetrachloroethylene or dichloroethane or carbon tetrachloride into a synthesis reaction kettle of 2, 4-dichlorophenoxyacetic acid (2, 4-D), and optionally adding acetic acid aqueous solution. Adding a catalyst: introducing chlorine into any two or three of 4-Dimethylaminopyridine (DMAP), iron phthalocyanine, ferric trichloride and benzenesulfonic acid, and keeping the temperature for 1-2 hours; transferring the obtained product to a crystallization kettle, cooling, crystallizing, centrifuging and drying to obtain the 2, 4-dichlorophenoxyacetic acid product. The mass ratio of the phenoxyacetic acid to the solvent is 1: 1-100; the mass ratio of the total mass of the catalyst to the phenoxyacetic acid is 1: 50-800; introducing chlorine gas for reaction at the temperature of 40-100 ℃; the temperature for cooling and crystallizing is 10-30 ℃; the molar ratio of the phenoxyacetic acid to the total amount of the introduced chlorine is 1: 2-2.2.
2) The organic solvent separated by centrifugation is recycled to synthesize the 2, 4-dichlorophenoxyacetic acid (2, 4-D).
3) Hydrochloric acid which is a byproduct recovered in the reaction process is used for acidifying and synthesizing phenoxyacetic acid.
4) The synthesis of 2, 4-dichlorophenoxyacetic acid (2, 4-D) can also be carried out in a selected microreactor:
mixing phenoxyacetic acid with a solvent, adding a catalyst, heating to 65-85 ℃, adding the mixture into a microreactor through a pump, and introducing liquid chlorine for reaction. The diameter of the microporous membrane selected by the microreactor is 1 micron-10 microns, the channel size of the flow-through phase is 1 mm-10 mm, the reaction time is 0.1-30 minutes, and the reaction temperature is 65-85 ℃. In the present invention, a membrane-dispersed microstructure reactor is preferably selected. The number of microchannel reactors is not particularly limited. When more than 2 microchannel reactors are used, each microchannel reactor is configured in series, and reaction raw materials sequentially enter each microchannel reactor. The structure of the microchannel reactor includes, but is not limited to, a rectangle, a trapezoid, a heart, a double trapezoid, and an irregular shape. In the reaction, the microchannel reactor may be used as different modules as needed, such as a mixing preheating module, a reaction module, a cooling module, and the like. These modules are only functionally distinct and the geometry may be identical.
10. The organic solvent of the cyclic reaction for synthesizing the 2, 4-dichlorophenoxyacetic acid (2, 4-D) is recovered by distillation or rectification for recycling after being used for a certain number of times. The residual liquid is mixed into the waste water of synthesizing phenoxyacetic acid and treated by adopting a catalytic oxidation mode.
The specific implementation mode is as follows:
the following examples are provided to further illustrate the essence of the present invention, but are not intended to limit the present invention.
Example (b):
1) adding 500 g of chloroacetic acid aqueous solution with the content of 60% into a 1000ml four-neck flask, keeping the temperature at 30-40 ℃, and introducing 54 g of ammonia;
2) 298.8 g of phenol and 200 g of water are added into a 2000ml four-neck flask with heating, condensation reflux and stirring functions, the temperature is heated to 65 ℃, 54 g of ammonia is introduced, and the temperature is controlled between 65 ℃ and 75 ℃. After ammonia introduction is finished, dropwise adding a potassium hydroxide aqueous solution, and adjusting the pH value to 12;
3) dropwise adding the ammonium chloroacetate aqueous solution obtained in the step 1) into the four-neck flask obtained in the step 2), controlling the temperature to be 90-100 ℃, dropwise adding a potassium hydroxide aqueous solution during the dropwise adding process, adjusting the pH value to 11.5-12, and after the dropwise adding is finished, keeping the temperature and reacting for 20 minutes. Cooling to 60 deg.C, adding 30% hydrochloric acid, adjusting pH to 2, and cooling to 20 deg.C. Filtering and washing to obtain a crude product of phenoxyacetic acid;
4) refining phenoxyacetic acid by melting, heating to 190 deg.C, and distilling off residual phenol and water. Cooling and weighing to obtain 458.3 g of refined phenoxyacetic acid with the content of 99.1 percent and the content of free phenol less than 5 ppm.
5) Filtering the separated water solution in the step 3), introducing ammonia to adjust the pH value to 8, and then passing through a resin adsorption column filled with 717 type anion resin. And (3) carrying out reduced pressure concentration on the aqueous solution adsorbed by the adsorption resin through a rotary evaporator, cooling, crystallizing, filtering and drying to obtain 281 g of ammonium chloride.
6) 229 g of refined phenoxyacetic acid with the content of 99.1 percent is added into a 2000ml four-neck flask with the functions of heating, condensing reflux and stirring, 600 g of dichloroethane is added, 1 g of catalyst 4-Dimethylaminopyridine (DMAP) and 3 g of benzenesulfonic acid are added, the temperature is raised to 60 ℃, chlorine is introduced, the temperature is controlled to be 60-80 ℃, and 234 g of chlorine is introduced. Keeping the temperature for 1 hour, then transferring the materials into a crystallization kettle to be cooled to 10 ℃, and obtaining 280.6g of 2, 4-dichlorophenoxyacetic acid product after suction filtration, washing and drying, wherein the total yield is 80 percent, the content is 96.5 percent, and the filtered mother liquor is recycled.
7) Taking the filtered mother liquor obtained in the step 6), adding 229 g of refined phenoxyacetic acid with the content of 99.1 percent, adding 0.1 g of catalyst 4-Dimethylaminopyridine (DMAP) and 0.3 g of benzenesulfonic acid, heating to 60 ℃, starting introducing chlorine, controlling the temperature to be 60-80 ℃, and introducing 234 g of chlorine. Keeping the temperature for 1 hour, then transferring the materials into a crystallization kettle to be cooled to 10 ℃, and obtaining 336.6g of 2, 4-dichlorophenoxyacetic acid product after suction filtration, washing and drying, wherein the total yield is 96 percent, the content is 96.4 percent, and the filtered mother liquor is recycled.
Claims (8)
1. A method for preparing phenoxyacetic acid and preparing 2, 4-dichlorphenoxyacetic acid (2.4-D) in environment protecting mode, through ammonia and potassium hydroxide, replace sodium hydroxide, utilize nanofiltration membrane separation and resin adsorption process, separate phenol and phenoxyacetic acid that retrieve residual in the waste water, the by-product obtains the agricultural ammonium chloride containing potassium chloride, or contain the agricultural ammonium sulfate of potassium chloride, react with the micro reactor apparatus, characterized by that the method includes the following steps:
1) adding chloroacetic acid aqueous solution into a continuous or intermittent reactor, introducing ammonia (or adding ammonium bicarbonate), controlling the temperature at 10-40 ℃ to obtain chloroacetic acid ammonium aqueous solution, wherein the molar ratio of chloroacetic acid to ammonia is 1: 1-1.1, the molar ratio of chloroacetic acid to ammonium bicarbonate is 1: 1-1.1, and the content of chloroacetic acid in the chloroacetic acid aqueous solution is 30-70%;
2) adding water and phenol into a condensation reaction kettle, introducing ammonia (or adding ammonium bicarbonate) under the protection of nitrogen, controlling the molar ratio of phenol to ammonia to be 1: 1-1.1, controlling the molar ratio of phenol to ammonium bicarbonate to be 1: 1-1.1, controlling the temperature to be 65-85 ℃, and adding potassium hydroxide or adjusting the pH value of the solution to 10-12 after the reaction is finished;
3) after the condensation reaction kettle in the step 2) finishes the reaction, heating to 90-110 ℃, dropwise adding the ammonium chloroacetate aqueous solution obtained in the step 1), adjusting the pH value in the solution to 10-12 by potassium hydroxide, and after the ammonium chloroacetate aqueous solution is added, keeping the temperature and reacting for 10-30 minutes;
4) step 2) reaction of phenol and ammonia can also be carried out in a microreactor;
5) step 4) regulating the pH value of the reaction liquid obtained by the microreactor to 10-12 by using potassium hydroxide, heating to 60-110 ℃, and adding the reaction liquid and the ammonium chloroacetate aqueous solution obtained in the step 1) into the microreactor at the same time according to the proportion by using a pump, introducing the potassium hydroxide aqueous solution, keeping the pH value in the microreactor to be 10-12, and reacting for 0.1-30 minutes;
6) transferring the reaction liquid obtained in the step 3) or the step 5) into an acidification kettle, cooling, dropwise adding hydrochloric acid or sulfuric acid for acidification, adjusting the pH value to 1-5, cooling to 15-35 ℃, and centrifugally separating out a crude phenoxyacetic acid product;
7) separating water and residual phenol in the crude phenoxyacetic acid product in a melting refining mode under the protection of nitrogen to obtain refined phenoxyacetic acid;
8) adding a certain amount of water into the water solution centrifugally separated in the step 6), introducing ammonia (or adding sulfuric acid) to adjust the pH value of the water solution to 6-8, and separating by using nanofiltration membrane equipment to obtain nanofiltration permeating liquid and nanofiltration trapped liquid;
9) nanofiltration permeate, namely, firstly, separating phenol and phenoxyacetic acid remained in an aqueous solution by adsorption of adsorption resin, recovering the phenol and the phenoxyacetic acid after desorption, carrying out multi-effect evaporation, cooling crystallization and centrifugation on the nanofiltration permeate subjected to resin adsorption treatment to obtain an ammonium chloride fertilizer raw material byproduct containing potassium chloride or an ammonium sulfate fertilizer raw material byproduct containing potassium chloride;
10) nanofiltration trapped fluid is directly used for dissolving chloroacetic acid or phenol and is recycled;
11) the water solution centrifugally separated in the step 4) can also be directly adsorbed by using an adsorption resin, organic matters in the water solution are separated, phenol and phenoxyacetic acid are recovered through desorption, the water solution is subjected to multi-effect evaporation, cooling crystallization and centrifugation to obtain an ammonium chloride fertilizer raw material containing potassium chloride or an ammonium sulfate fertilizer raw material byproduct containing potassium chloride;
12) a small amount of residual liquid left after multi-effect evaporation or wastewater after impurity enrichment of nanofiltration trapped fluid after multiple times of trapping is treated by adopting a catalytic oxidation mode;
13) 2, 4-dichlorphenoxyacetic acid (2, 4-D) is prepared and subjected to chlorination reaction in a microreactor.
2. The method of claim 1, wherein: introducing ammonia or adding ammonium bicarbonate for reaction in the step 1) and the step 2).
3. The method of claim 1, wherein: and 2) regulating the pH value of the solution to 10-12 by adding potassium hydroxide in the step 3).
4. The method of claim 1, wherein: the diameter of the microporous membrane of the microchannel reactor in the step 4) and the step 5) is 1 micron-10 microns, the channel size of the flow-through phase is 1 millimeter-10 millimeters, and the reaction time is 0.1-30 minutes.
5. The method of claim 1, wherein: and 7) separating water and residual phenol in the crude phenoxyacetic acid product obtained in the step 7) by adopting a melting refining mode to obtain fine phenoxyacetic acid.
6. The method of claim 1, wherein: and 9) recovering phenol and phenoxyacetic acid in the wastewater by using an adsorption resin adsorption mode in the step 11).
7. The method of claim 1, wherein: step 9) and step 11) to obtain the ammonium chloride fertilizer raw material containing potassium chloride or the ammonium sulfate fertilizer raw material byproduct containing potassium chloride.
8. The method of claim 1, wherein: the 2, 4-dichlorophenoxyacetic acid (2, 4-D) prepared in the step 13) is subjected to chlorination reaction in a microreactor, the diameter of a microporous membrane of the microchannel reactor is 1-10 microns, the channel size of a flow-through phase is 1-10 mm, and the reaction time is 0.1-30 minutes.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112521268A (en) * | 2020-12-03 | 2021-03-19 | 枣庄学院 | Method for preparing 2,4-D acid by using micro-reaction device |
| CN114163321A (en) * | 2021-12-16 | 2022-03-11 | 湖南化工研究院有限公司 | Preparation method of 3,4, 5-trichlorobenzaldehyde |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112521268A (en) * | 2020-12-03 | 2021-03-19 | 枣庄学院 | Method for preparing 2,4-D acid by using micro-reaction device |
| CN114163321A (en) * | 2021-12-16 | 2022-03-11 | 湖南化工研究院有限公司 | Preparation method of 3,4, 5-trichlorobenzaldehyde |
| CN114163321B (en) * | 2021-12-16 | 2024-04-30 | 湖南化工研究院有限公司 | Preparation method of 3,4, 5-trichlorobenzaldehyde |
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