Method for preparing 2,3-/2,6-dichloroaniline

Abstract

The invention relates to a method for preparing 2,3- / 2,6-dichloroaniline, and especially relates to a method for preparing 2,3- / 2,6-dichloroaniline through aminolysis. The technological route of the method is characterized in that 2,3- / 2,6-dichloroaniline is obtained through aminolysis of a raw material 1,2,3-trichlorobenzene which is a byproduct in the dichlorobenzene production process. A catalysis amount of a catalyst and a cocatalyst are added in the production process, so the addition of triethylamine is avoided, and the method has the advantages of simple process flow, low cost, and few three wastes.

Description

technical field [0001] The invention relates to a method for preparing 2,3- / 2,6-dichloroaniline, in particular to a method for preparing 2,3- / 2,6-dichloroaniline by ammonolysis. Background technique [0002] 2,3-dichloroaniline and 2,6-dichloroaniline are important intermediates of organic raw materials. 2,3-Dichloroaniline is widely used in fine chemical industries such as pesticides, medicines, dyes and photosensitive materials. 2,6-Dichloroaniline is used in the pharmaceutical industry to synthesize quinone acid antibacterial drugs lomefloxacin, ofloxacin, diuretic acid and clonidine, etc., and in the pesticide industry to synthesize herbicides. [0003] Regarding the synthesis line of 2,3-dichloroaniline, 2,3-dichloronitrobenzene is mainly used as a raw material. Patent EP536070 mentions that tungsten carbide is used as a catalyst and obtained by hydrogenation reduction. The main problem is that the hydrogenation process is harmful to the The material requirements of t...

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Problems solved by technology

[0003] Regarding the synthesis line of 2,3-dichloroaniline, 2,3-dichloronitrobenzene is mainly used as a raw material. Patent EP536070 mentions that tungsten carbide is used as a catalyst and obtained by hydrogenation reduction. The main problem is that the hydrogenation process is harmful to the The equipment material requirements are high, and there are certain safety hazards; the second is that the preparation and purification routes of 2,3-dichloronitrobenzene are relatively cumbersome, resulting in high raw material costs

[0004] There are many synthetic routes for 2,6-dichloroaniline. Using p-aminobenzenesulfonamide as the starting material, methanol is used as the solvent to directly pass through chlorine gas chlorination to obtain 3,5-dichloro-4-aminobenzenesulfonamide. Then use 70% sulfuric acid to carry out hydrolysis to remove sulfonamide group and make, two-step total yield 56-61% (Lv Hongchu, Zhejiang Chemical Industry [J], 32 (1): 48-49, 2001), there is main problem is Raw material p-aminobenzenesulfonamide price is relatively high, resulting in high production cost

Patent CN95102807 mentions that 1,6-diphenylurea is prepared by reacting aniline as the starting material with urea. After sulfonation, chlorination and hydrolysis to remove the sulfonic acid group, 2,6-dichloroaniline is obtained, and the yield is increased to 65%. The main problem is that the reaction selectivity is poor, the waste liquid is large, and the equipment requirements are high.

The patent CN1827584 made an improvement, using N,N'-di(o-chlorophenyl)urea as raw material, after sulfonation, chlorination, hydrolysis, and rectification to obtain the finished product 2,6-dichloroaniline, with a yield of more than 76% , there is a problem that 98% sulfuric acid is used in a large amount in the reaction process, and a large amount of waste acid is produced, which is difficult to handle

[0005] In addition, there is an article mentioning the preparation of dichloroaniline by ammonolysis method, using s-trichlorobenzene and ammonia (ammonia water) as raw materials, copper powder or copper acetate as catalyst, triethylamine as acid binding agent, controlling a certain temperature and pressure, ammonolysis Obtain 3,5-dichloroaniline yield can reach about 80% (Cao Guanghong, Hubei chemical industry [J], 1993 (2): 24-27), there is main problem one, and catalyst consumption is big, adopts copper powder to make catalyst consumption reach The feeding amount of trichlorobenzene is 20%; the second is that the ammonolysis process needs to add a large amount of triethylamine, which increases the production cost and separation difficulty, and produces a large amount of saline wastewater

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