阅读说明：本技术 一种邻氨基三氟甲苯的合成方法 (Synthesis method of o-amino benzotrifluoride ) 是由 郑龙生 方东 张亮 李付香 于 2018-07-02 设计创作，主要内容包括：本发明公开了一种邻氨基三氟甲苯的合成方法。以以三氟甲苯为原料,经过硝化、还原二步反应得到目标化合物。本发明与现有技术相比,1、本发明以三氟甲苯为原料,来源广泛,制备方便；2、本发明采用常压、低温进行硝化反应,物料对管道、设备腐的蚀较小,对环境及操作人员相对安全可靠；3、本发明以廉价的镍催化剂代替常用的钯、铂等贵金属催化剂,降低生产成本,作溶剂的甲醇回收方便,可以循环使用,减少了生产过程的有机物的排放。(The invention discloses a synthesis method of o-amino benzotrifluoride. The target compound is obtained by taking benzotrifluoride as a raw material through two steps of reactions of nitration and reduction. Compared with the prior art, the invention 1 uses benzotrifluoride as the raw material, has wide source and convenient preparation; 2. the invention adopts normal pressure and low temperature for nitration reaction, the corrosion of materials to pipelines and equipment is small, and the invention is relatively safe and reliable to environment and operators; 3. the invention uses cheap nickel catalyst to replace common noble metal catalyst such as palladium, platinum and the like, reduces the production cost, has convenient recovery of methanol used as solvent, can be recycled, and reduces the emission of organic matters in the production process.)

1. A synthetic method of o-amino benzotrifluoride is characterized in that: the method comprises the following steps of taking benzotrifluoride as a raw material, and obtaining a target compound through nitration, reduction reaction and rectification, wherein the steps are as follows:

1) a nitration step: preparing mixed acid formed by mixing nitric acid and sulfuric acid in a nitration reaction kettle, then dropwise adding a certain amount of benzotrifluoride, carrying out nitration reaction at normal pressure and low temperature, controlling the temperature at 35-45 ℃, standing for liquid separation after reaction, adding 105 sulfuric acid into a lower-layer waste acid layer to prepare 85% sulfuric acid, partially recycling, and selling the rest in a byproduct form; adding water into the organic matter on the upper layer, washing, standing and layering to obtain a nitrobenzotrifluoride mixture, and allowing the wastewater to enter a sewage treatment facility;

2) a reduction step: adding the intermediate nitrobenzotrifluoride mixture into a reduction reaction kettle, taking methanol as a solvent and Raney nickel as a catalyst, heating to 100-115 ℃ by using steam, introducing hydrogen, and carrying out hydrogenation reduction reaction under the conditions of 100-115 ℃, 2.5-4.0 MPa of heat preservation and pressure maintaining;

3) a rectification step: after the reaction in the previous step is finished, distilling at the temperature of 60-65 ℃ under normal pressure to recycle the solvent methanol, and rectifying the residual liquid in a negative pressure manner under the conditions of 0.09MPa and 115-125 ℃ to obtain the o-amino benzotrifluoride.

2. The method for synthesizing ortho-aminobenzotrifluoride according to claim 1, wherein: the mass ratio of the mixed acid in the nitration step is as follows: 1:1.7 to 1.8.

3. The method for synthesizing ortho-aminobenzotrifluoride according to claim 1, wherein: the mass ratio of the benzotrifluoride and the mixed acid in the nitration step is as follows: 1: 1.37 to 1.38.

4. The method for synthesizing ortho-aminobenzotrifluoride according to claim 1, wherein: the mass ratio of the intermediate nitrobenzotrifluoride mixture to the catalyst in the reduction step is as follows: 1: 0.001 to 0.002.

Technical Field

The invention relates to a preparation method of a pesticide chemical product, in particular to a novel synthesis process of o-amino benzotrifluoride. The method is suitable for the occasion of synthesizing the o-amino benzotrifluoride by taking the benzotrifluoride as a raw material, nitrating with mixed acid and carrying out catalytic hydrogenation reduction under normal pressure.

Background

The o-amino benzotrifluoride is colorless or light yellow transparent liquid, has the relative density of 1.282, the melting point of 34-35 ℃, the boiling point of 174-175 ℃, is slightly soluble in water, is easily soluble in organic solvents such as alcohol, ether and the like, is an important fluorine-containing medical intermediate which is increasingly widely applied in recent years, and has very wide application in the industries such as medicine, pesticide, dye and the like. The product is also an important intermediate for synthesizing fluorine-containing herbicide, medicine and dye, and is used as an intermediate for producing plastic plasticizer products.

The existing main synthetic routes of o-aminobenzotrifluoride include the following types: 1) from the by-product of the synthesis of m-aminobenzotrifluoride. The method is to obtain ortho-position and meta-position amino benzotrifluoride by nitration of benzotrifluoride, reduction hydrogenation or reduction of sodium sulfide or iron powder. Due to the meta-position effect of trifluoromethyl, most of m-nitrobenzotrifluoride is generated in the nitration process, and the content of o-nitrobenzotrifluoride is only about 10%; 2) meta-amino trifluorotoluene route. Reacting m-amino benzotrifluoride with acetic anhydride to generate m-acetamido benzotrifluoride, nitrifying to generate 3-acetamido-5-nitro-benzotrifluoride, hydrogenating to reduce nitro, and de-acetylating to generate o-amino benzotrifluoride. The method needs more reaction steps and has high cost; 3) an ortho-chlorotrifluoromethane ammonolysis route. The reaction is mostly carried out by using Co, Ni, Cu, CaO/Cu in ammonia water₂Cl₂Taking o-chlorotrifluoromethane as a catalyst, and carrying out ammonolysis to obtain o-amino benzotrifluoride; 4) aniline trifluoromethylation route. The method is a free radical reaction of aniline and trifluoromethyl free radical, and the reactant is a mixture of o-amino benzotrifluoride and p-amino benzotrifluoride due to the positioning effect of o-position and p-position of amino, wherein the o-position is more. The raw materials and the products can be separated by a vacuum rectification method; 5) 2-amino-5-chlorotrifluoromethylene route. 2-amino-5-chlorotrifluoromethane is an important medical intermediate, so that the source of the product is in short supply and the price is high, so that the cost for synthesizing the o-amino-benzotrifluoride by using the raw material is high, and the market competitiveness is poor; 6) meta-bromotrifluorotoluene route. M-bromobenzotrifluoride is nitrified by mixed acid, the product is mainly 2-nitro-5-bromobenzotrifluoride, the latter can reduce the nitro and remove the bromine under the condition of catalytic hydrogenation reduction, thereby obtaining o-amino benzotrifluoride, the synthesis of the o-amino benzotrifluoride by the o-trichloromethyl phenyl isocyanate can be divided into the fluorination of the o-trichloromethyl phenyl isocyanate and the hydrolysis process of the o-trifluoromethyl phenyl isocyanate; 7) an ortho-trichloromethyl phenyl isocyanate route; 8) trifluorotoluene route. The o-amino benzotrifluoride is prepared by chlorination, nitration and hydrogenation reduction of the benzotrifluoride.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the prior art and provides a novel synthesis method of o-amino benzotrifluoride, which takes the benzotrifluoride as a raw material and obtains a target compound through two steps of nitration and reduction reaction.

The technical solution of the invention is as follows:

(1) and (4) nitration. Preparing mixed acid (a mixture of nitric acid and sulfuric acid) in a nitration reaction kettle, dropwise adding a certain amount of benzotrifluoride, carrying out nitration reaction at normal pressure and low temperature, controlling the temperature at 35-45 ℃ (normal pressure), standing for liquid separation after reaction, adding 105 sulfuric acid into a lower-layer waste acid layer to prepare 85% sulfuric acid, recycling part of sulfuric acid, and selling the rest of sulfuric acid in a byproduct form. Adding water into the organic matter on the upper layer, washing, standing and layering to obtain a nitrobenzotrifluoride mixture, and allowing the wastewater to enter a sewage treatment facility. The reaction formula is as follows:

(2) and (4) reducing. Adding the mixture of the nitrobenzotrifluoride into a reduction reaction kettle (purged by nitrogen before adding), heating to 100-115 ℃ by using steam and introducing hydrogen by using methanol as a solvent and a nickel catalyst as a catalyst, and carrying out hydrogenation reduction reaction under the conditions of heat preservation and pressure maintenance (100-115 ℃ and 2.5-4.0 MPa).

(3) After the reaction is finished, firstly distilling (65 ℃ and normal pressure) for recycling the solvent methanol, then condensing and layering the distillate, sending the wastewater to a sewage treatment workshop, and sending the organic layer to a qualification unit for disposal. And (3) rectifying the residual liquid obtained by distillation at the temperature of between 115 and 125 ℃ under negative pressure (0.09 MPa) to obtain m-trifluoromethylaniline (120 +/-2 ℃), o-trifluoromethylaniline (118 +/-2 ℃) and p-trifluoromethylaniline (123 +/-2 ℃), and treating the rectification residues by qualified units. The reaction formula is as follows:

in the nitration reaction step, the operation process of preparing mixed acid is as follows: metering sulfuric acid into a preparation kettle, then metering nitric acid, and continuously stirring to obtain the nitric acid and sulfuric acid with the mass ratio: 1:1.7 to 1.8.

In the nitration reaction step, the mass ratio of the used raw materials of benzotrifluoride to the mixed acid is as follows: 1: 1.37 to 1.38.

In the reduction reaction step, air is displaced before hydrogenation: the hydrogenation was carried out after 3 consecutive purges with nitrogen (< 1 MPa), with purge gas being vented through the vent.

In the reduction reaction step, hydrogen is displaced after hydrogenation: purging was continued 3 times with nitrogen (< 1 MPa) and then a post-treatment procedure was performed, venting the purge gas through the vent.

In the reduction reaction step, the mass ratio of the intermediate nitrobenzotrifluoride mixture to the catalyst is as follows: 1: 0.001 to 0.002.

Due to the adoption of the technical scheme, the invention has the beneficial effects that the economic benefit and the social benefit are obvious:

1. the invention takes the benzotrifluoride as the raw material, has wide source and convenient preparation;

2. the invention adopts normal pressure and low temperature for nitration reaction, the corrosion of materials to pipelines and equipment is small, and the invention is relatively safe and reliable to environment and operators;

3. the invention uses cheap nickel catalyst to replace common noble metal catalyst such as palladium, platinum and the like, reduces the production cost, has convenient recovery of methanol used as solvent, can be recycled, and reduces the emission of organic matters in the production process.

Detailed Description

The following examples further illustrate the invention in order to provide a better understanding of the invention. The examples do not limit the scope of the invention in any way. Modifications and adaptations of the present invention within the scope of the claims may occur to those skilled in the art and are intended to be within the scope and spirit of the present invention.