阅读说明：本技术 一种2,4(2,6)-二甲基硝基苯的制备方法 (Preparation method of 2,4(2,6) -dimethyl nitrobenzene ) 是由 朱益民 于 2021-07-27 设计创作，主要内容包括：一种2,4(2,6)-二甲基硝基苯的制备方法,是以间二甲苯、N-甲基吡咯烷酮磺酸盐、硝基甲烷、碘化亚铜为原料,包括硝化、分离和干燥,与现有技术的区别是所述的硝化是在以间二甲苯、N-甲基吡咯烷酮磺酸盐、硝基甲烷(硝基乙烷)存在条件下搅拌控温在5～10℃下反应6小时,反应结束后旋蒸回收溶剂、水洗除盐,分液,干燥得到2,4-二甲基硝基苯和2,6-二甲基硝基苯。本方法条件温和、反应平稳、质量稳定、工艺简单、操作方便,适合规模化生产。(A preparation method of 2,4(2,6) -dimethyl nitrobenzene is characterized in that m-xylene, N-methylpyrrolidone sulfonate, nitromethane and cuprous iodide are used as raw materials, and the method comprises the steps of nitration, separation and drying, wherein the difference from the prior art is that the nitration is carried out for 6 hours under the condition that the m-xylene, the N-methylpyrrolidone sulfonate and nitromethane (nitroethane) exist, the solvent is recovered by rotary evaporation after the reaction is finished, the salt is removed by water washing, liquid separation is carried out, and drying is carried out to obtain the 2, 4-dimethyl nitrobenzene and the 2, 6-dimethyl nitrobenzene. The method has the advantages of mild conditions, stable reaction, stable quality, simple process, convenient operation and suitability for large-scale production.)

1. A preparation method of 2,4(2,6) -dimethyl nitrobenzene is characterized in that m-xylene, N-methylpyrrolidone sulfonate, nitromethane and cuprous iodide are used as raw materials, and the method comprises the steps of nitration, separation and drying, wherein the difference from the prior art is that the nitration is carried out for 6 hours under the condition that the m-xylene, the N-methylpyrrolidone sulfonate and nitromethane (nitroethane) exist, the solvent is recovered by rotary evaporation after the reaction is finished, the salt is removed by water washing, liquid separation is carried out, and drying is carried out to obtain the 2, 4-dimethyl nitrobenzene and the 2, 6-dimethyl nitrobenzene.

2. The method of claim 1, wherein: the system is selected from nitromethane and nitroethane.

3. The method of claim 1, wherein: the catalyst is N-methyl pyrrolidone sulfonate and cuprous iodide, N-methyl pyrrolidone methyl sulfonate and cuprous iodide, N-methyl pyrrolidone benzene sulfonate and cuprous iodide.

One, the technical field

The invention relates to a preparation method of 2,4(2,6) -dimethyl nitrobenzene.

Second, background Art

Meta-xylene is the main feedstock for the production of 2,4(2,6) -dimethylnitrobenzene. 2,4(2,6) -dimethyl nitrobenzene is an important intermediate of pesticide, dye, medicine and photosensitive material.

2, 4-dimethyl nitrobenzene is used for synthesizing formamidine, formamidine and thiacloprid on pesticides; producing solvent orange, acid red, disperse yellow, solvent yellow and direct violet on the dye; are also important intermediates for 3, 5-dimethylaniline and 2, 4-dimethylacetanilide.

2, 6-dimethyl nitrobenzene can be used for preparing metalaxyl, benalaxyl, furalaxyl, oxadixyl and propamocarb on pesticides; producing acid orange, direct red, acid violet, etc. on the dye; the lidocaine and the veterinary medicine jingsongling are synthesized in medicine.

At present, the industrial nitration method for preparing 2,4(2,6) -dimethyl nitrobenzene mainly comprises the following steps:

1. nitration with dilute nitric acid

Generally used for the nitration of aromatic compounds containing strong first type directing groups, the reaction is carried out in stainless steel or enamel equipment.

2. Nitration of concentrated nitric acid

This nitration often uses a large excess of nitric acid, which must be managed to be used or recovered, thus limiting its practical use.

3. Homogeneous nitration in concentrated sulfuric acid medium

When the nitrated compound or nitrated product is in the solid state at the reaction temperature, the nitrated compound is often dissolved in a large amount of concentrated sulfuric acid and then nitrated by adding a mixture of sulfuric acid and nitric acid. This method requires only a small excess of nitric acid, generally resulting in a high yield, but has the disadvantage of using an excessive amount of sulfuric acid.

4. Heterogeneous mixed acid nitration when both the nitrated compound and the nitrated product are liquid at the reaction temperature, the nitration reaction is usually carried out using a heterogeneous mixed acid, with vigorous stirring to disperse the organic phase into the acid phase. This nitration process has many advantages and is currently the most common and important nitration process in the industry.

5. Nitration in organic solvents

The advantage of this process is that with different solvents it is often possible to vary the ratio of the nitroisomeric products obtained, avoiding the use of large amounts of sulphuric acid as solvent and of nitric acid close to the theoretical amount. The application range of the method is likely to expand along with the reduction of the price of the solvent, and common organic solvents are acetic acid, ethyl acetate, dichloromethane, dichloroethane and the like.

The methods have the problems of concentration and recycling of waste acid after nitration, treatment of nitration washing wastewater and the like.

Third, the invention

Aiming at the defects in the prior art, the invention aims to provide a preparation method of 2,4(2,6) -dimethyl nitrobenzene, and aims to solve the technical problem of selecting a nitration process which is environment-friendly and has good regioselectivity.

The technical scheme adopted by the invention for solving the technical problem is as follows.

The invention takes m-xylene as raw material, 2,4(2,6) -dimethyl nitrobenzene is obtained after nitration, and the reaction formula is as follows:

the preparation method of the 2,4(2,6) -dimethyl nitrobenzene is characterized in that m-xylene, N-methylpyrrolidone sulfonate, nitromethane (nitroethane) and cuprous iodide are used as raw materials, and the method comprises the steps of nitration, separation and drying, and is different from the prior art in that the nitration is carried out for 6 hours under the conditions of stirring and temperature control at 5-10 ℃ in the presence of the m-xylene, the N-methylpyrrolidone sulfonate and the nitromethane, the nitromethane (nitroethane) is recovered by rotary evaporation after the reaction is finished, and the 2, 4-dimethyl nitrobenzene and the 2, 6-dimethyl nitrobenzene are obtained by washing, desalting, separating and drying.

The system is selected from nitromethane and nitroethane.

The catalyst is selected from N-methyl pyrrolidone sulfonate and cuprous iodide, N-methyl pyrrolidone methyl sulfonate and cuprous iodide, N-methyl pyrrolidone benzene sulfonate and cuprous iodide.

The nitration method has mild conditions, stable reaction, easy control, good reaction zone selectivity, simplified process and greatly reduced cost. The catalyst has less consumption and high conversion rate of the raw materials, the conversion rate is more than or equal to 99 percent, and the 2, 4-dimethyl nitrobenzene and the 2, 6-dimethyl nitrobenzene have a ratio of 3: 1.

Fourth, detailed description of the invention

Preparation of (mono) 2, 4-dimethyl nitrobenzene

1. Adding 5g of N-methylpyrrolidone sulfonate, 80g of nitromethane and 10g of m-xylene into a two-neck glass flask with a reflux condenser tube, stirring and controlling the temperature to be 5-10 ℃, adding 0.2g of cuprous iodide, stirring and controlling the temperature to react for 6 hours, tracking by TLC (thin layer chromatography) until the m-xylene completely reacts, carrying out rotary evaporation to remove the nitromethane and recycling, washing with water to remove salts, separating liquid, and drying to obtain 14.11g of 2, 4-dimethyl nitrobenzene and 2, 6-dimethyl nitrobenzene (the ratio is 3: 1).

2. Adding 5.2g of N-methylpyrrolidone methyl sulfonate, 80g of nitromethane and 10g of m-xylene into a two-neck glass flask with a reflux condenser tube, stirring and controlling the temperature to be 5-10 ℃, adding 0.2g of cuprous iodide, stirring and controlling the temperature to react for 6 hours, tracking by TLC (thin layer chromatography) until the m-xylene completely reacts, carrying out rotary evaporation to remove the nitromethane and recover the nitromethane, washing with water to remove salt, separating liquid, and drying to obtain 13.76g of 2, 4-dimethyl nitrobenzene and 2, 6-dimethyl nitrobenzene (the ratio is 3: 1).

3. Adding 5g of N-methylpyrrolidone sulfonate, 98g of nitroethane and 10g of m-xylene into a two-neck glass flask with a reflux condenser tube, stirring and controlling the temperature to be 5-10 ℃, adding 0.2g of cuprous iodide, stirring and controlling the temperature to react for 6 hours, tracking by TLC (thin layer chromatography) until the m-xylene completely reacts, carrying out rotary evaporation to remove nitromethane and recycling, washing with water to remove salt, separating liquid, and drying to obtain 14.15g of 2, 4-dimethyl nitrobenzene and 2, 6-dimethyl nitrobenzene (the ratio is 3: 1).

4. Adding 5.2g of N-methylpyrrolidone methyl sulfonate, 98g of nitroethane and 10g of m-xylene into a two-neck glass flask with a reflux condenser tube, stirring and controlling the temperature to be 5-10 ℃, adding 0.2g of cuprous iodide, stirring and controlling the temperature to react for 6 hours, tracking by TLC (thin layer chromatography) until the m-xylene completely reacts, carrying out rotary evaporation to remove nitromethane and recover, washing with water to remove salt, separating liquid, and drying to obtain 13.98g of 2, 4-dimethyl nitrobenzene and 2, 6-dimethyl nitrobenzene (the ratio is 3: 1).

5. Adding 7.3g of N-methylpyrrolidone benzene sulfonate, 80g of nitromethane and 10g of m-xylene into a two-neck glass flask with a reflux condenser tube, stirring and controlling the temperature to be 5-10 ℃, adding 0.2g of cuprous iodide, stirring and controlling the temperature to react for 6 hours, tracking by TLC (thin layer chromatography) until the m-xylene completely reacts, carrying out rotary evaporation to remove the nitromethane and recover the nitromethane, washing with water to remove salt, separating liquid, and drying to obtain 13.69g of 2, 4-dimethylnitrobenzene and 2, 6-dimethylnitrobenzene (the ratio is 3: 1).