阅读说明：本技术 一种2,6-二氯-4-三氟甲基苯胺的合成新方法 (Novel synthesis method of 2, 6-dichloro-4-trifluoromethylaniline ) 是由 郑龙生 方东 张亮 李付香 于 2018-06-28 设计创作，主要内容包括：本发明公开了一种2,6-二氯-4-三氟甲基苯胺的合成新方法。以对三氟甲基苯胺为原料,滴加一定量的磺酰氯,氯化、水洗、减压精馏后得到目标化合物。本发明与现有技术相比,工艺简单、易于操作；反应时间短、收率高；生产成本较低、易于工业化生产。是环境友好的化工过程,有良好的工业化应用前景。(The invention discloses a new method for synthesizing 2, 6-dichloro-4-trifluoromethyl aniline. Taking p-trifluoromethylaniline as a raw material, dropwise adding a certain amount of sulfonyl chloride, and carrying out chlorination, washing and vacuum rectification to obtain a target compound. Compared with the prior art, the invention has simple process and easy operation; the reaction time is short, and the yield is high; the production cost is low, and the industrial production is easy to realize. Is an environment-friendly chemical process and has good industrial application prospect.)

1. A method for preparing 2, 6-dichloro-4-trifluoromethylaniline is characterized by comprising the following steps: adding p-trifluoromethylaniline into a corresponding solvent, dropwise adding a certain amount of sulfonyl chloride at the reaction temperature of 0-70 ℃, controlling the reaction temperature of 30-70 ℃ after dropwise adding, continuing to react for 1-15 hours, washing with water to remove inorganic salts after the reaction is finished, concentrating an organic phase, and performing reduced pressure rectification to obtain the corresponding 2, 6-dichloro-4-trifluoromethylaniline, wherein the reaction formula is as follows:

2. the process according to claim 1 for preparing 2, 6-dichloro-4-trifluoromethylaniline, wherein: the solvent is one or a mixed solvent of two or more of N, N-dimethylformamide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride and dichloroethane.

3. The process according to claim 1 for preparing 2, 6-dichloro-4-trifluoromethylaniline, wherein: the molar ratio of sulfonyl chloride to p-trifluoromethylaniline is 1-10: 1.

Technical Field

The invention relates to a new method for preparing 2, 6-dichloro-4-trifluoromethylaniline, belonging to the technical field of chemical material preparation. The method is suitable for the occasion of synthesizing the 2, 6-dichloro-4-trifluoromethyl aniline by taking the p-trifluoromethyl aniline and the sulfonyl chloride as raw materials and reacting under normal pressure.

Background

2, 6-dichloro-4-trifluoromethyl aniline is an important pesticide synthesis intermediate, and is mainly used for synthesizing fluorine-containing organic pesticides such as fipronil. Fipronil is the first choice of chemical pesticide of the present pollution-free agricultural and sideline products, has the characteristics of high efficiency, long effect, broad spectrum, small dosage, safety to human, livestock and environment, mildness to natural enemies of insects and beneficial organisms and the like, and has wide market prospect. The main preparation methods of the 2, 6-dichloro-4-trifluoromethylaniline include the following methods:

(1) 4-chloro-trifluoromethyl-benzene is used as a raw material, and a product is prepared through two steps of reactions, namely amination and chlorination. For example, in the first amination disclosed in the world patent WO 2004037766, 4-chlorotrifluoromethylbenzene, cuprous chloride, potassium fluoride, ammonia gas and methanol are sequentially added into an autoclave, stirred and heated to 190-; the second step of chlorination is to dissolve 4-trifluoromethyl aniline in glacial acetic acid and introduce chlorine gas at 60 deg.c to react to obtain the product. The conversion of the amination reaction in the first step of the process is very low.

(2) 2, 6-dichloro-4-trifluoromethyl phenyl isocyanate is taken as a raw material to prepare the product by one-step reaction. US patent US 5471002 discloses that the reaction is carried out in an autoclave, the air in the autoclave is replaced by nitrogen, then anhydrous hydrogen fluoride is introduced, the temperature is raised to 70 ℃ with stirring, and the temperature is maintained for 5 hours. In the reaction process, pressure is required to be continuously released so as to discharge the produced hydrogen chloride and carbonyl fluoride and keep the pressure stable. The method has complex process and the yield is only 70 percent.

(3) 2, 6-dichloroaniline and sodium trifluoromethanesulfonate are used as raw materials to prepare a product by one-step reaction (Bernard et al, trifluoromethyl of aromatic compounds with a sodium trifluoromethyl fluoride and anion exchanger, Tetrahedron Lett. 1991,51(32): 7525-7528). The method uses acetonitrile/water as a mixed solvent, a divalent copper salt as a catalyst, a free radical initiator, namely tert-butyl hydroperoxide and a trifluoromethyl methylating reagent, namely sodium trifluoromethanesulfonate, and the yield is about 30 percent.

(4) 3, 4-dichloro-benzotrifluoride is used as a raw material, and a product is prepared through three steps of reactions. US patent US 6410737 discloses first incubating 3, 4-dichloro-trifluorotoluene with hydrazine hydrate, pyridine at 150 ℃ for 6 hours to obtain the intermediate 2-chloro-4-trifluoromethylphenylhydrazine; then stirring the mixture in a Raney-Ni catalyst and an ethanol solvent for 5 hours in a high-pressure kettle to obtain 2-chloro-4-trifluoromethylaniline; finally, chlorination reaction is carried out in carbon tetrachloride solvent by sulfuryl chloride to obtain the product. The method has complex process flow and low total yield.

(5) U.S. Pat. No. 4, 5401882 and Chinese patent No. 1435413 disclose 4-chloro-benzotrifluoride as a raw material, which is subjected to dimethyl amination reaction to obtain 4-trifluoromethyl-N, N-dimethylaniline, then sulfuryl chloride is dropped into carbon tetrachloride for chlorination to obtain 2, 6-dichloro-4-trifluoromethyl-N, N-dimethylaniline, and finally, under the irradiation of an ultraviolet lamp, a chlorine target compound is introduced. The method has multiple steps and low total yield.

(6) P-trifluoromethylaniline is used as an initial raw material and is chloridized by chlorine to obtain the 2, 6-dichloro-4-trifluoromethylaniline. For example, in chinese patent CN 101143829, p-trifluoromethylaniline is used as a starting material, and the 2, 6-dichloro-4-trifluoromethylaniline is obtained by chlorination with chlorine gas and then rectification. The method uses chlorine, has strict requirements on the control of the reaction end point, otherwise, the by-product is rapidly increased, and the difference between the boiling points of the by-product and the product is small, thereby bringing certain difficulty to the post-treatment.

(7) 3,4, 5-trichlorobenzotrifluoride is used as a starting material, and 2, 6-dichloro-4-trifluoromethylaniline is obtained through high-pressure ammonolysis. U.S. Pat. No. 4, 7777079 discloses the chlorination of p-chlorotrifluoromethyltoluene starting material to give 3,4, 5-trichlorobenzotrifluoride, followed by high pressure ammonolysis to give 2, 6-dichloro-4-trifluoromethylaniline. Although the production cost is reduced, the ammonolysis needs to be carried out under the conditions of high temperature and high pressure, so that the method has higher requirements on equipment and certain potential safety hazards in production.

Disclosure of Invention

The invention aims to provide a preparation method of 2, 6-dichloro-4-trifluoromethylaniline, which is simple in operation process and easy to industrialize.

The technical solution for realizing the purpose of the invention is as follows: adding p-trifluoromethylaniline into a corresponding solvent, controlling the temperature of a reaction system at 0-70 ℃, dropwise adding a certain amount of sulfonyl chloride, controlling the reaction temperature after dropwise adding to continuously react for 1-15 hours, washing with water to remove inorganic salts after the reaction is finished, concentrating an organic phase, and performing reduced pressure rectification to obtain the target compound 2, 6-dichloro-4-trifluoromethylaniline.

The solvent is one or a mixed solvent of two or more of N, N-dimethylformamide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride and dichloroethane, wherein the mixed solvent of one or two of chloroform and dichloroethane is preferred.

The molar ratio of sulfonyl chloride to p-trifluoromethylaniline is 1-10: 1, preferably 1.5 to 4: 1.

the preferable temperature for controlling the dripping temperature of the sulfonyl chloride is 0-40 ℃.

After the sulfuryl chloride is dripped, the reaction temperature is controlled to be 30-70 ℃.

The preferable time for continuing the reaction after the dropwise addition of the sulfonyl chloride is 4-8 hours.

The invention relates to a method for preparing 2, 6-dichloro-4-trifluoromethylaniline, which comprises the steps of taking p-trifluoromethylaniline as a raw material, controlling the reaction temperature, dropwise adding a certain amount of chlorinating agent sulfonyl chloride, washing with water to remove inorganic salts after the reaction is finished, concentrating an organic phase, and carrying out reduced pressure rectification to obtain the corresponding 2, 6-dichloro-4-trifluoromethylaniline.

The chemical reaction process according to the invention is as follows:

according to the method for preparing 2, 6-dichloro-4-trifluoromethylaniline, the technical key is that para-trifluoromethylaniline is used as a raw material, sulfonyl chloride is used as a chlorinating agent, the reaction temperature is controlled, and chlorination reaction is carried out; after the reaction is finished, washing with water to remove inorganic salt in the reaction solution, concentrating an organic phase, and then carrying out vacuum rectification to obtain the corresponding 2, 6-dichloro-4-trifluoromethylaniline. Compared with the prior art, the invention has the advantages that: (1) the process is simple and easy to operate; (2) the reaction time is short, and the yield is high; (3) the production cost is low, and the industrial production is easy to realize. Is an environment-friendly chemical process and has good industrial application prospect.

Detailed Description

The present invention is described in detail below by way of examples, which are provided for clarity of disclosure and are not to be construed as limiting the invention.