阅读说明：本技术 一种嗪草酮的制备方法 (Preparation method of metribuzin ) 是由 纪雷 姜宇华 周彬 奚学根 吕宜飞 于 2019-09-30 设计创作，主要内容包括：本发明涉及一种嗪草酮的制备方法,使4-氨基-6-叔丁基-3-巯基-1,2,4-三嗪-5(4H)-酮和三氟甲磺酸甲酯在甲苯和三氟甲磺酸的存在下反应制得所述的嗪草酮。本发明的原料成本低、制备方法简单,嗪草酮的纯度和收率高,废水处理难度小、成本低,同时产生的低COD废水可以回收利用,生产过程中无毒副作用,适合工业化生产。(The invention relates to a preparation method of metribuzin, which is prepared by reacting 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone and methyl trifluoromethanesulfonate in the presence of toluene and trifluoromethanesulfonic acid. The raw material cost of the invention is low, the preparation method is simple, the purity and the yield of metribuzin are high, the wastewater treatment difficulty is small, the cost is low, the generated low COD wastewater can be recycled, and the production process has no toxic or side effect and is suitable for industrial production.)

1. A preparation method of metribuzin is characterized by comprising the following steps: reacting 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazin-5 (4H) -one with methyl trifluoromethanesulfonate in the presence of toluene and trifluoromethanesulfonic acid to produce the metribuzin.

2. The process for preparing metribuzin of claim 1, wherein: the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the methyl trifluoromethanesulfonate is 1-1.5: 1.

3. The process for preparing metribuzin of claim 1, wherein: the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the trifluoromethanesulfonic acid is 13-14: 1.

4. The process for preparing metribuzin of claim 1, wherein: the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the toluene is 3-4: 1.

5. The process for preparing metribuzin of claim 1, wherein: and controlling the reaction temperature to be 20-25 ℃.

6. The process for the preparation of metribuzin according to any one of claims 1 to 5, characterized in that: toluene and trifluoromethanesulfonic acid are added into a reactor, the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone is added under stirring, the temperature is reduced to 5-10 ℃, methyl trifluoromethanesulfonate is added dropwise, the temperature in the dropwise adding process is controlled to be 15 ℃ or below, and then the metribuzin is prepared through heat preservation reaction at 20-25 ℃.

7. The process for preparing metribuzin of claim 6, wherein: and controlling the dropping time of dropping the methyl trifluoromethanesulfonate to be 50-70 min, and controlling the time of the heat preservation reaction to be 2-4 h.

8. The process for preparing metribuzin of claim 1, wherein: after the reaction is finished, carrying out post-treatment to obtain the metribuzin, wherein the post-treatment method comprises the following steps: cooling to 15 ℃ or below, adding water to quench reaction, dropwise adding liquid alkali at the temperature of 15 ℃ or below, adjusting the pH to 5.5-6.5, layering, adding toluene into a water layer to extract, combining toluene layers, washing the toluene layers with liquid alkali, then washing with water, layering, recovering toluene from the toluene layers through reduced pressure distillation, and drying the solid in vacuum to obtain the metribuzin.

9. The process for preparing metribuzin of claim 8, wherein: and (3) combining the water layers obtained by layering in the steps, then recovering water through reduced pressure distillation, separating out salt, adding the salt into ethanol, stirring and refluxing, filtering, recovering ethanol from mother liquor, and drying the solid to obtain sodium trifluoromethanesulfonate.

10. The process for preparing metribuzin of claim 9, wherein: the using amount of the ethanol is 2-3 times of the feeding mass of the methyl trifluoromethanesulfonate.

Technical Field

The invention particularly relates to a preparation method of metribuzin.

Background

Metribuzin, common english name: metribuzin, chemical name: 4-amino-6- (1, 1-dimethylethyl) -3-methylthio-1, 2, 4-triazine-5-tetrahydroketone is a systemic conduction type herbicide, is mainly absorbed by roots, stems and leaves can also be absorbed, metribuzin plays a role in killing weeds by inhibiting photosynthesis of sensitive plants, germination and emergence of sensitive weeds are not affected after application, leaves are faded after emergence, and finally nutrition is exhausted and died. The pesticide effect of metribuzin is greatly influenced by the soil type, organic matter content, humidity and temperature, and the use condition is more strict, and if the metribuzin is not used properly, the metribuzin is possibly ineffective or even causes phytotoxicity.

The common synthesis methods reported in the literature mostly adopt methanol as a solvent, and in the presence of inorganic base, triazine ketone is subjected to sulfydryl methylation by using methylating agents such as methyl bromide, methyl chloride and the like to obtain a product, and the reaction equation is as follows:

in the process, metribuzin is precipitated in a solid form, the mother liquor contains unreacted triazinone, byproducts of azomethine, methanol, halogen sodium salt and other organic matters which are difficult to treat, and the high-salt high-COD wastewater is one of the difficulties of the metribuzin production process.

In the literature, the other traditional methanol-sulfuric acid method needs a long-time reflux reaction, has low conversion rate, low production efficiency and poor product quality, generates waste water with large sulfur odor, contains a large amount of organic wastes of ketones and triazines in the waste water with high COD, and is difficult to be biochemically treated and has poor oxidizability. Other problems such as high reaction temperature, long time, low atom utilization rate, small equipment treatment capacity, difficult purification of generated byproducts, low yield, large odor of the obtained wastewater, high post-treatment cost and the like are difficult to solve when dimethyl sulfate is used as a methylation reagent.

Disclosure of Invention

The invention aims to provide a method for preparing metribuzin, which is simple, low in cost and less in by-product.

In order to solve the technical problems, the invention adopts the following technical scheme:

a process for preparing metribuzin comprises reacting 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazin-5 (4H) -one (triazinone for short) with methyl trifluoromethanesulfonate in the presence of toluene and trifluoromethanesulfonic acid.

The reaction equation of the invention is as follows:

the invention takes the conveniently purchased triazone on the market as the raw material, takes the common solvent toluene as the solvent, takes the trifluoromethanesulfonic acid as the catalyst, and takes the methyl trifluoromethanesulfonate as the methylation reagent, so that the raw material cost is low, the side reaction in the reaction process is less, the atom utilization rate is high, the post-treatment is simple, the environmental protection pressure is low, and the method is suitable for industrial production.

In addition, the method takes the toluene as a solvent, has high recovery rate and proper boiling point, can reduce the cost and shorten the production period, and the produced metribuzin has high purity and high yield, and the produced wastewater is easy to treat and meets the requirements of safety and environmental protection.

Preferably, the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the methyl trifluoromethanesulfonate is 1-1.5: 1, and further preferably 1.03-1.2: 1.

Preferably, the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the trifluoromethanesulfonic acid is 13-14: 1.

Preferably, the feeding mass ratio of the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone to the toluene is 3-4: 1.

Preferably, the reaction temperature is controlled to be 20-25 ℃.

Preferably, toluene and trifluoromethanesulfonic acid are added into a reactor, the 4-amino-6-tert-butyl-3-mercapto-1, 2, 4-triazine-5 (4H) -ketone is added under stirring, the temperature is reduced to 5-10 ℃, methyl trifluoromethanesulfonate is added dropwise, the temperature in the dropwise adding process is controlled to be 15 ℃ or lower, and then the metribuzin is prepared by heat preservation reaction at 20-25 ℃.

Further preferably, the dropping time of dropping the methyl trifluoromethanesulfonate is controlled to be 50-70 min, and the time of the heat preservation reaction is controlled to be 2-4 h.

Preferably, after the reaction is finished, performing post-treatment to obtain the metribuzin, wherein the post-treatment method comprises the following steps: cooling to 15 ℃ or below, adding water to quench reaction, dropwise adding liquid alkali at the temperature of 15 ℃ or below, adjusting the pH to 5.5-6.5, layering, adding toluene into a water layer to extract, combining toluene layers, washing the toluene layers with liquid alkali, then washing with water, layering, recovering toluene from the toluene layers through reduced pressure distillation, and drying the solid in vacuum to obtain the metribuzin.

Preferably, the water layers obtained by layering in the steps are combined, then water is recovered by reduced pressure distillation, salt is separated out, the salt is added into ethanol, stirred and refluxed, then filtration is carried out, ethanol is recovered from mother liquor, and the solid is dried to obtain the sodium trifluoromethanesulfonate.

More preferably, the using amount of the ethanol is 2-3 times of the mass of the methyl trifluoromethanesulfonate.

The water and toluene distilled off in the post-treatment step can be recycled, for example, the water can be used for preparing liquid alkali or quenching reaction, etc.

Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:

the raw material cost of the invention is low, the preparation method is simple, the purity and the yield of metribuzin are high, the wastewater treatment difficulty is small, the cost is low, the generated low COD wastewater can be recycled, and the production process has no toxic or side effect and is suitable for industrial production.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It is to be understood that these embodiments are provided to illustrate the basic principles, essential features and advantages of the present invention, and the present invention is not limited by the following embodiments. The implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not indicated are generally the conditions in routine experiments. The contents are all mass contents.