Synthetic process of 2,4-dichloro-5-hydroxyl phenyl hydrazine

Abstract

The invention provides a synthetic process of 2,4-dichloro-5-hydroxyl phenyl hydrazine. According to the method, 2,4-dichloro-5-hydroxyl aniline, ketazine and water are used as raw materials, and the 2,4-dichloro-5-hydroxyl phenyl hydrazine is synthesized through reaction at a certain temperature. Excessive ketazine and water are added in the reaction process to make the 2,4-dichloro-5-hydroxyl phenyl hydrazine completely react in a reaction system, reduced pressure distillation is adopted to remove the water and the ketazine after reaction is completed, and a solid substance is washed and dried to obtain the 2,4-dichloro-5-hydroxyl phenyl hydrazine. Compared with a traditional diazo-reaction process for synthesizing the 2,4-dichloro-5-hydroxyl phenyl hydrazine, the process includes few reaction steps and is simple, the device requirements are not high, reaction is easy to control, the yield is high, the production process is low, waste discharge is little, and the process is a green and environment-friendly production process.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a synthesis method of 2,4-dichloro-5-hydroxyphenylhydrazine. Background technique [0002] 2,4-dichloro-5-hydroxyphenylhydrazine is an intermediate in the synthesis of 1,2,4,5-tetrasubstituted benzene nitrogen-containing heterocyclic herbicides, such as oxadiazone, propargyl oxadiazone, chloralkyne oxadiazone Grassone, etc. The mechanism of action of these herbicides is the same as that of diphenyl ether herbicides, which are protoporphyrinogen oxidase inhibitors. Its biggest feature is high activity, low toxicity, and environmental friendliness. It is not only safe for the current crops, but also has no effect on the subsequent crops. It is a herbicide with very promising prospects. [0003] At present, the synthetic methods of 2,4-dichloro-5-hydroxyphenylhydrazine cannot avoid operations such as diazotization, reduction, acidification, alkali analysis o...

AI Technical Summary

Problems solved by technology

[0003] At present, the synthetic methods of 2,4-dichloro-5-hydroxyphenylhydrazine cannot avoid operations such as diazotization, reduction, acidification, alkali analysis of 2,4-dichloro-5-hydroxyaniline, and these operations have a great influence on the reaction temperature. The requirements are more stringent, both diazotization and reduction reactions must be carried out at low temperature, and the addition rate of sodium nitrite solution and the degree of reaction are not well controlled, and side reactions will occur and lead to the generation of by-products, which will also affect the following reduction reactions. have an impact

The process route using sodium sulfite or sodium bisulfite as a reducing agent is relatively mature and has been widely used in the industrial production of 2,4-dichloro-5-hydroxyphenylhydrazine, but its control conditions are many, the process is complicated, and the operation is cumbersome. If it is necessary to use sodium hydroxide solution to adjust the pH value to 6.5~7, if the control is not good, there will be asphalt-like by-products, and the reaction temperature needs to be adjusted several times during the whole process

When using tin protochloride as reducing agent, not only the reagents are relatively expensive, the reaction temperature is lower, cooling equipment is needed, the cost increases, and the yield is not high, SnCl 4 and SnCl 2 Difficult to recycle, easy to cause environmental pollution

[0004] In addition, the existing technology still has the following problems and disadvantages: (1) many reaction steps, complex process, high requirements for equipment, low yield (the total reaction yield is only 70-80%), and high production cost; (2) In the production process, the hydrochloric acid, sodium hydroxide, sulfite or stannous chloride and reaction by-products used eventually enter the wastewater, resulting in a large amount of salt-containing organic wastewater, which is difficult to treat. The treatment cost is high, the waste discharge is large, and it is easy to cause environmental pollution; (3) There are many safety hazards in the diazotization and reduction process, and the concentration of diazonium salt should not be too high, otherwise it will increase the danger of production. The sulfite used will produce sulfur dioxide gas as a by-product, which is toxic and corrosive to a certain extent, and requires high equipment

Images