阅读说明：本技术 一种1,2,3-三氯-4,6-二硝基苯的制备方法 (Preparation method of 1,2, 3-trichloro-4, 6-dinitrobenzene ) 是由 王培兰 何志勇 金钢 孔伟伟 于 2018-09-06 设计创作，主要内容包括：一种制备1,2,3-三氯-4,6-二硝基苯的方法,采用两步法工艺制备1,2,3-三氯-4,6-二硝基苯：将1,2,3-三氯苯与95%~98.5%浓硫酸混合后,滴加硝酸反应,将反应生成的有机相与硝化废酸分离后,再将有机相加入浓硫酸,滴加硝酸进行二硝化反应,二硝化反应分离后的废酸作为下一批次一硝化用酸。采用二步法制备1,2,3-三氯-4,6-二硝基苯,可减少制备过程所需要的硫酸原料,同时,可减少硝化过程产生的废酸量。(A method for preparing 1,2, 3-trichloro-4, 6-dinitrobenzene adopts a two-step process to prepare the 1,2, 3-trichloro-4, 6-dinitrobenzene: mixing 1,2, 3-trichlorobenzene and 95% -98.5% concentrated sulfuric acid, dropwise adding nitric acid for reaction, separating an organic phase generated by the reaction from nitrified waste acid, adding the organic phase into the concentrated sulfuric acid, dropwise adding nitric acid for dinitration reaction, and taking the waste acid separated by dinitration reaction as the acid for primary nitration of the next batch. The two-step method is adopted to prepare the 1,2, 3-trichloro-4, 6-dinitrobenzene, so that the sulfuric acid raw material required in the preparation process can be reduced, and the waste acid amount generated in the nitration process can be reduced.)

1. A method for preparing 1,2, 3-trichloro-4, 6-dinitrobenzene is characterized in that the 1,2, 3-trichloro-4, 6-dinitrobenzene is prepared by adopting a two-step method: firstly, mixing 1,2, 3-trichlorobenzene with 95% -98% concentrated sulfuric acid in a reactor, and then metering 65% -68% nitric acid under a stirring state; after the reaction is finished, transferring the reaction liquid into a liquid separator for heat preservation, standing for layering, and separating out lower-layer nitrified waste acid; secondly, transferring the separated organic phase into a reactor, adding concentrated sulfuric acid, stirring, heating, and dropwise adding nitric acid to perform dinitration reaction; thirdly, transferring the dinitration reaction liquid into a liquid separator, preserving heat, standing, layering to separate dinitration waste acid, wherein the organic phase is the prepared 1,2, 3-trichloro-4, 6-dinitrobenzene; fourthly, adding 1,2, 3-trichlorobenzene into the reactor, adding dinitrated waste acid into the reactor, dropwise adding nitric acid to perform mononitration reaction, and repeating the operation steps of 1-3 to prepare the 1,2, 3-trichloro-4, 6-dinitrobenzene.

2. The method of claim 1, wherein the molecular ratio of dinitration concentrated sulfuric acid to 1,2, 3-trichlorobenzene is 5.8-6.3.

3. The method of claim 1, wherein the molecular ratio of mononitration nitric acid to 1,2, 3-trichlorobenzene is 1.0 to 1.15.

4. The method of claim 1, wherein the molecular ratio of dinitration nitric acid to 1,2, 3-trichlorobenzene is 1.2 to 1.25.

5. The method according to claim 1, wherein the temperature for keeping the temperature of the primary nitration liquid at rest and liquid separation is 60-65 ℃.

6. The method according to claim 1, wherein the temperature for keeping the reaction solution of dinitration still, separated and kept at 93-95 ℃.

7. The process according to claim 1, characterized in that the dinitration sulfuric acid dehydration number is greater than 8.2.

Technical Field

The invention relates to the field of organic chemical synthesis, and introduces a preparation method of 1,2, 3-trichloro-4, 6-dinitrobenzene (hereinafter referred to as TCDNB).

Background

Poly (p-phenylene benzobisoxazole) (PBO for short) is a high-performance fiber, and is used in military, aerospace and other fields at present, 4, 6-diamino resorcinol (DAR for short) hydrochloride is one of important monomers for synthesizing fiber PBO, and the DAR is prepared by using trichlorobenzene as raw material and through the steps of nitration, hydrolysis, hydrogenation, crystallization and the like.

In the nitration process, 1,2, 3-trichlorobenzene is mixed with sulfuric acid, and then nitric acid is added dropwise to prepare TCDNB, because dinitration reaction is carried out, the requirement on the dehydration value of the sulfuric acid is high, the input amount of the nitration reaction sulfuric acid is large, the ratio of the nitration reaction sulfuric acid to the trichlorobenzene mole number reaches more than 11, the consumption amount of the nitration reaction sulfuric acid is large, and the amount of waste acid generated after nitration is finished is large.

In US4766244 and the literature^[1]In the DCDNB preparation method introduced in (1), in order to achieve the dehydration value required for dinitration, the molecular ratio of the raw materials 1,2, 3-trichlorobenzene to sulfuric acid is 1: 11.3.

disclosure of Invention

The technical problems to be solved by the invention are as follows: TCDNB preparation is a dinitration, and the dehydration value requirements for sulfuric acid to complete the mononitration and dinitration are different, the dehydration value required for the mononitration being lower than that required for the dinitration. The invention utilizes the difference and adopts a two-step process to prepare TCDNB: mixing 1,2, 3-trichlorobenzene with concentrated sulfuric acid, dropwise adding nitric acid for reaction, separating an organic phase generated by the reaction from nitrified waste acid, adding the organic phase into the concentrated sulfuric acid, dropwise adding nitric acid for dinitration, and taking the waste acid separated by dinitration as a primary nitration mixed acid raw material of the next batch.

The two-step method is adopted to prepare the 1,2, 3-trichloro-4, 6-dinitrobenzene, so that the sulfuric acid raw material required in the preparation process can be reduced, and the waste acid amount generated in the nitration process can be reduced.

The technical scheme of the invention is that a method for preparing 1,2, 3-trichloro-4, 6-dinitrobenzene adopts a two-step method to prepare 1,2, 3-trichloro-4, 6-dinitrobenzene: firstly, mixing 1,2, 3-trichlorobenzene with 95% -98% concentrated sulfuric acid in a reactor, and dropwise adding 65% -68% nitric acid under a stirring state; after the reaction is finished, transferring the reaction liquid into a liquid separator for heat preservation, standing for layering, and separating out lower-layer nitrified waste acid; secondly, transferring the separated organic phase into a reactor, adding concentrated sulfuric acid, stirring, heating, and dropwise adding nitric acid to perform dinitration reaction; thirdly, transferring the dinitration reaction liquid into a liquid separator, preserving heat, standing, layering to separate dinitration waste acid, wherein the organic phase is the prepared 1,2, 3-trichloro-4, 6-dinitrobenzene; fourthly, adding 1,2, 3-trichlorobenzene into the reactor, adding dinitrated waste acid into the reactor, dropwise adding nitric acid to perform mononitration reaction, and repeating the operation steps of 1-3 to prepare the 1,2, 3-trichloro-4, 6-dinitrobenzene.

The molecular ratio of the dinitration concentrated sulfuric acid to the 1,2, 3-trichlorobenzene is 5.8-6.3.

The molecular ratio of the mononitration nitric acid to 1,2, 3-trichlorobenzene is 1.0-1.15.

The molecular ratio of the dinitration reaction nitric acid to the 1,2, 3-trichlorobenzene is 1.2-1.25.

And the temperature of the primary nitration liquid after standing, liquid separation and heat preservation is 60-65 ℃.

And standing the dinitration reaction liquid, separating liquid and keeping the temperature at 93-95 ℃.

The sulfuric acid dehydration value of the dinitration reaction is more than 8.2.

The invention has the advantages of

The method adopts a two-step process to prepare TCDNB: mixing 1,2, 3-trichlorobenzene and concentrated sulfuric acid, dropwise adding nitric acid under stirring to perform primary nitration reaction, after the reaction is finished, separating an organic phase from waste acid, adding concentrated sulfuric acid again, continuously dropwise adding nitric acid until the reaction is finished, and using the separated nitrified waste acid after the dinitration reaction as the mixed acid raw material of the next batch of primary nitration reaction. The invention can reduce the sulfuric acid consumption in the TCDNB preparation process by half, and on one hand, the aim of reducing waste acid is achieved; on the other hand, the consumption of sulfuric acid is reduced, the aim of reducing the preparation cost is finally realized, and the market competitiveness of the product is enhanced.

Detailed Description

The present invention will be further described with reference to the following examples.