阅读说明：本技术 一种2,4-二氯-3,5-二硝基三氟甲苯的制备方法 (Preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride ) 是由 胡红一 汪静莉 赵辉 常亚军 顾仁宝 杨露 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种2,4-二氯-3,5-二硝基三氟甲苯的制备方法,首先以2,4-二氯三氟甲苯为原料进行第一步硝化反应,反应后相分离成废酸和硝化中间体；再将发烟硝酸和发烟硫酸混合成混酸,与硝化中间体进行第二步硝化反应,反应后相分离成半废酸和目标化合物2,4-二氯-3,5-二硝基三氟甲苯；其中第二步硝化反应分离出来的半废酸可直接循环用于第一步硝化反应中,与2,4-二氯三氟甲苯混合,进行新一轮的硝化反应。本发明的2,4-二氯-3,5-二硝基三氟甲苯的制备方法在常压下分两步反应,操作简单,成品纯度高；第二步硝化产生的半废酸可供第一步硝化反应直接使用,即实现了循环经济,又减少了废酸排放。(The invention discloses a preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises the steps of firstly, carrying out a first-step nitration reaction by taking 2, 4-dichlorobenzotrifluoride as a raw material, and separating into waste acid and a nitration intermediate after the reaction; then mixing fuming nitric acid and fuming sulfuric acid into mixed acid, carrying out a second-step nitration reaction on the mixed acid and a nitration intermediate, and separating the mixed acid and the nitration intermediate into semi-waste acid and a target compound 2, 4-dichloro-3, 5-dinitrobenzotrifluoride after the reaction; wherein, the half waste acid separated from the second step nitration reaction can be directly recycled for the first step nitration reaction, and is mixed with 2, 4-dichlorobenzotrifluoride for a new round of nitration reaction. The preparation method of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride provided by the invention has the advantages that the reaction is carried out in two steps under normal pressure, the operation is simple, and the purity of the finished product is high; the half waste acid generated by the second step of nitration can be directly used for the first step of nitration reaction, thereby realizing circular economy and reducing the discharge of waste acid.)

1. A preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is characterized by comprising the following steps: 2, 4-dichloro-3, 5-dinitro trifluorotoluene is prepared by taking 2, 4-dichloro trifluorotoluene as a raw material through two-step nitration reaction; wherein, the half waste acid generated by the second step of nitration can be recycled, and the specific method comprises the following steps:

firstly, carrying out nitration reaction on 2, 4-dichlorotrifluorotoluene, fuming nitric acid and fuming sulfuric acid, and separating liquid-liquid phase after the reaction into waste acid and a nitration intermediate compound 2, 4-dichloro-3-nitrotrifluorotoluene;

secondly, completely dissolving the nitration intermediate compound 2, 4-dichloro-3-nitrobenzotrifluoride in fuming sulfuric acid, then dropwise adding mixed acid mixed by fuming nitric acid and fuming sulfuric acid in proportion for nitration reaction, separating liquid from liquid phase after reaction, washing the upper layer crude product with water to obtain a 2, 4-dichloro-3, 5-dinitrobenzotrifluoride crude product, and directly using the lower layer half waste acid for the first-step nitration reaction;

step three, recrystallizing the crude product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride in the step two by using dichloroethane as a solvent, and then drying in vacuum to obtain a finished product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride;

wherein, the half waste acid separated by the second step of nitration directly enters the first step of nitration reaction kettle, and is mixed with the raw material 2, 4-dichlorobenzotrifluoride for a new round of nitration reaction.

2. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the first step, the molar ratio of the materials 2, 4-dichlorotrifluorotoluene, fuming nitric acid and fuming sulfuric acid used in the nitration reaction is 1: 2-3: 4-6; in the second step, the molar ratio of the material 2, 4-dichloro-3-nitrobenzotrifluoride, fuming nitric acid and fuming sulfuric acid used in the nitration reaction is 1: 4-5: 12-15.

3. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the first step, the temperature of the nitration reaction is 40-50 ℃, and the time of the nitration reaction is 3-4 h.

4. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the second step, the temperature of the nitration reaction is 100-110 ℃, and the time of the nitration reaction is 14-16 h.

5. The process according to claim 4 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the second step, the temperature of the nitration reaction is firstly increased to 100 ℃, the reaction lasts for 8-9h, then the temperature is increased to 110 ℃, and the reaction lasts for 6-7 h.

6. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the second step, the dropping temperature is 50-60 ℃.

7. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: in the nitration reaction method in the first step, the first batch can be carried out according to a conventional nitric acid-sulfuric acid mixed acid method, and the second batch and the subsequent nitration reactions directly use the semi-waste acid generated after the nitration reaction in the second step for reaction.

8. The process according to claim 1 for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which comprises: and in the third step, the temperature of the vacuum drying is 40-50 ℃.

Technical Field

The invention belongs to the technical field of organic synthesis and preparation, and particularly relates to a preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride.

Background

2, 4-dichloro-3, 5-dinitrobenzotrifluoride is an intermediate for fine organic synthesis and is commonly used for synthesis of pesticides, medicines and dyes. As mentioned in Design and Synthesis of New Mitochondrin Cytotoxin N-thiadiazolidines which is the inhibitor Tumor Cell Growth, Hori Hitoshi et al, 2, 4-dichloro-3, 5-dinitrobenzotrifluoride can be synthesized in a yield of about 60% by mixing fuming sulfuric acid with fuming nitric acid as a nitrating agent and reacting with 2, 4-dichlorobenzotrifluoride at 80 ℃ for 96 hours with stirring. U.S. Pat. No. 4,4201724 describes the use of SO in a proportion of 30 to 33%₃The fuming sulfuric acid and 90 percent nitric acid are taken as nitrating agents and react with the 2, 4-dichlorotrifluorotoluene for 96 hours under the temperature of 76 +/-1 ℃ by stirring, and the yield of the 2, 4-dichloro-3, 5-dinitrotrifluorotoluene is about 79 percent. Molla M. et al, in the text of Synthesis evaluation of organic chemistry against Toxoplasma gondii, have adopted this method as well, not only the waste acid is difficult to post-treat, but also the reaction time is longer, the energy consumption is higher.

Patent CN 103304420A discloses a clean preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, wherein a crude product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is washed, neutralized, refined and dried in vacuum to obtain a dinitrated pure product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride. Repeated tests according to the experimental conditions described in the patent show that the final dinitrated product obtained has a low purity of about 85-90%. Meanwhile, the activity of the waste acid treated after the primary nitration is generated (the effect of extracting concentrated acid by adopting cyclohexane is not ideal), the content of the 2, 4-dichloro-3, 5-dinitro benzotrifluoride synthesized in the batch is about 82 percent, the purity is low, and the specified quality standard cannot be achieved.

Disclosure of Invention

The invention aims to provide a preparation method of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, which not only adopts a new method to synthesize a high-purity product (the content is more than 98.5 percent) without changing a basic operation method, but also enables waste acid generated in the process of synthesizing a target compound to be recycled, is beneficial to environmental protection and cost saving, and accords with the development direction of green chemistry.

The technical scheme adopted by the invention for solving the problems is as follows: a method for preparing 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is characterized in that 2, 4-dichlorobenzotrifluoride is used as a raw material, and the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is prepared through two-step nitration reaction; wherein, the half waste acid generated by the second step of nitration can be recycled, and the specific method comprises the following steps:

in the first step, 2, 4-dichlorotrifluorotoluene, fuming nitric acid and fuming sulfuric acid are subjected to nitration reaction, and liquid-liquid phase separation is carried out after the reaction to obtain waste acid and a nitration intermediate compound 2, 4-dichloro-3-nitrotrifluorotoluene.

And secondly, completely dissolving the nitrated intermediate compound 2, 4-dichloro-3-nitrobenzotrifluoride in fuming sulfuric acid, then dropwise adding mixed acid mixed by fuming nitric acid and fuming sulfuric acid in proportion for nitration reaction, carrying out liquid-liquid phase separation after the reaction, washing the upper layer of crude product with water to obtain a crude product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, and directly using the lower layer of semi-waste acid for the first-step nitration reaction.

And thirdly, recrystallizing the crude product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride in the second step by using dichloroethane as a solvent, and then drying in vacuum to obtain the finished product of the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride.

Wherein, the half waste acid separated by the second step of nitration directly enters the first step of nitration reaction kettle, and is mixed with the raw material 2, 4-dichlorobenzotrifluoride for a new round of nitration reaction.

Preferably, the molar ratio of the materials 2, 4-dichlorotrifluorotoluene, fuming nitric acid and fuming sulfuric acid used in the nitration reaction in the first step is 1: 2-3: 4-6; in the second step, the molar ratio of the material 2, 4-dichloro-3-nitrobenzotrifluoride, fuming nitric acid and fuming sulfuric acid used in the nitration reaction is 1: 4-5: 12-15.

More preferably, the molar ratio of the materials 2, 4-dichlorotrifluorotoluene, fuming nitric acid and fuming sulfuric acid used in the nitration reaction in the first step is 1:3: 6; in the second step, the molar ratio of the material 2, 4-dichloro-3-nitrobenzotrifluoride, fuming nitric acid and fuming sulfuric acid used in the nitration reaction is 1:5: 15.

Preferably, the temperature of the nitration reaction in the first step is 40-50 ℃, and the time of the nitration reaction is 3-4 h.

Preferably, the temperature of the nitration reaction in the second step is 100-110 ℃, and the time of the nitration reaction is 14-16 h.

More preferably, in the second step, the temperature of the nitration reaction is firstly raised to 100 ℃, and after the nitration reaction is carried out for 8 to 9 hours, the temperature is raised to 110 ℃ and the nitration reaction is carried out for 6 to 7 hours.

Preferably, the dropping temperature in the second step is 50-60 ℃.

Preferably, in the nitration reaction method in the first step, the first batch can be carried out according to a conventional nitric acid-sulfuric acid mixed acid method, and the second batch and the subsequent nitration reactions directly use the half waste acid generated after the nitration reaction in the second step for reaction.

Preferably, the temperature of the vacuum drying in the third step is 40-50 ℃.

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

compared with the prior art, the invention has the advantages that:

(1) the method is carried out by two steps of reaction, has simple operation and short reaction time, and the semi-waste acid generated by the second step of nitration can be used for the first step of nitration for secondary reaction, thereby realizing circular economy, reducing waste acid discharge and being an environment-friendly chemical process.

(2) In the prior art, the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is generally washed after neutralization, which not only reduces the loss of product materials, but also increases the amount of waste water, while the 2, 4-dichloro-3, 5-dinitrobenzotrifluoride is directly washed without neutralization in the post-treatment process, 1, 2-dichloroethane is adopted as a solvent for recrystallization after washing, and then the high-purity 2, 4-dichloro-3, 5-dinitrobenzotrifluoride can be obtained by vacuum drying.

(3) The first-step nitration product 2, 4-dichloro-3-nitrobenzotrifluoride is dissolved in fuming sulfuric acid and then is subjected to a second-step nitration reaction with mixed acid, the first-step nitration product in a solution state can enable the raw materials to be in full reaction contact, and the yield is improved.

Drawings

FIG. 1 is a process flow diagram of the process for the preparation of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in FIG. 1, the process flow of the process for producing 2, 4-dichloro-3, 5-dinitrobenzotrifluoride in this example is shown.