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Preparation method of 2, 4, 6-trichlorophenylhydrazine

A technology of trichlorophenylhydrazine and trichloroaniline, which is applied in the fields of hydrazine preparation, organic chemistry, etc., can solve the problems of low yield, large waste discharge, and high equipment requirements, and achieves easy reaction control and less waste discharge. , the effect of low equipment requirements

Inactive Publication Date: 2017-10-03
李博强
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, the preparation methods of 2,4,6-trichlorophenylhydrazine cannot avoid operations such as diazotization, reduction, acidification, and alkali analysis of 2,4,6-trichloroaniline, and these operations have higher requirements on reaction temperature. , diazotization must be a low-temperature reaction, and if the rate of addition of sodium nitrite solution and the degree of reaction are not well controlled, side reactions will occur and lead to the formation of by-products, which will also affect the following reduction reactions
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 2,4,6-trichlorophenylhydrazine, but its control conditions are many, the process is complicated, and the operation is cumbersome. 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 stannous chloride is used as reducing agent, not only the reagents are relatively expensive, but the reaction temperature is low, refrigeration and cooling equipment is needed, the cost increases, and the yield is not high
[0004] In addition, the existing production methods still have the following problems and disadvantages: (1) many reaction steps, complex process, high requirements for equipment, low yield (only 70-80%), and high production cost; (2) in the production process In the process, the hydrochloric acid, sodium hydroxide, sulfite and reaction by-products used finally entered the wastewater, resulting in a large amount of salt-containing organic wastewater. The wastewater treatment is difficult and expensive, and the amount of waste discharge (3) There are many safety hazards in the diazotization and reduction process, the concentration of diazonium salt should not be too high, otherwise it will increase the risk of production, and the sulfite used in the reduction process will produce by-products Sulfur dioxide gas, which is toxic and corrosive to a certain extent, requires high equipment

Method used

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  • Preparation method of 2, 4, 6-trichlorophenylhydrazine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Put 196.5g of 2,4,6-trichloroaniline and 168g of acetonazine into a four-neck flask equipped with stirring, dropping funnel, thermometer and rectification column. The receiver of the rectification column is connected with a conduit to absorb ammonia Gas; start stirring, heat the solution to 120-130°C, slowly add 54ml of water dropwise into the four-neck flask, control the reaction temperature at 100°C-130°C, when the gas generated by the reaction enters the rectification column, Acetone is produced at a top temperature of 54°C to 58°C and ammonia gas is recovered. The water vapor and acetone azine entering the rectification column are condensed and flow back to the flask to continue to participate in the reaction; End the reaction after no ammonia gas is released from the receiver, evaporate all the water and acetonazine in the flask with negative pressure, recrystallize the solid matter in the flask with absolute ethanol, and dry to obtain 2,4,6-trichlorobenzene Hydraz...

Embodiment 2

[0014] Put 196.5g of 2,4,6-trichloroaniline and 196g of acetonazine into a four-neck flask equipped with stirring, dropping funnel, thermometer and rectification column. The receiver of the rectification column is connected with a conduit to absorb ammonia Gas; start stirring, heat the solution to 120-130°C, slowly add 63ml of water dropwise into the four-neck flask, control the reaction temperature at 100°C-130°C, when the gas generated by the reaction enters the rectification column, Acetone is produced at a top temperature of 54°C to 58°C and ammonia gas is recovered. The water vapor and acetone azine entering the rectification column are condensed and flow back to the flask to continue to participate in the reaction; End the reaction after no ammonia gas is released from the receiver, evaporate all the water and acetonazine in the flask with negative pressure, recrystallize the solid matter in the flask with absolute ethanol, and dry to obtain 2,4,6-trichlorobenzene Hydraz...

Embodiment 3

[0016] Put 196.5g of 2,4,6-trichloroaniline and 224g of acetonazine into a four-neck flask equipped with stirring, dropping funnel, thermometer and rectification column. The receiver of the rectification column is connected with a pipe to absorb ammonia Gas; start stirring, heat the solution to 120-130°C, slowly add 72ml of water dropwise into the four-neck flask, control the reaction temperature at 100°C-130°C, when the gas generated by the reaction enters the rectification column, Acetone is produced at a top temperature of 54°C to 58°C and ammonia gas is recovered. The water vapor and acetone azine entering the rectification column are condensed and flow back to the flask to continue to participate in the reaction; End the reaction after no ammonia gas is released from the receiver, evaporate all the water and acetonazine in the flask with negative pressure, recrystallize the solid matter in the flask with absolute ethanol, and dry to obtain 2,4,6-trichlorobenzene Hydrazine...

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Abstract

The invention discloses a preparation method of 2, 4, 6-trichlorophenylhydrazine. The preparation method comprises that 2, 4, 6-trichloroaniline, acetone azine and water as raw materials undergo a reaction at a certain temperature to produce 2, 4, 6-trichlorophenylhydrazine, in the reaction process, an excessive amount of acetone azine and water are added into the reaction system so that the 2, 4, 6-trichlorophenylhydrazine in the reaction system completely reacts, after the reaction, water and acetone azine are removed by reduced pressure distillation, the solids are recrystallized, and the crystals are dried to form 2, 4, 6-trichlorophenylhydrazine. Compared with the traditional diazotization reaction process for preparing 2, 4, 6-trichloroaniline, the preparation method provided by the invention has the advantages of less reaction steps, simple processes, low device requirements, control easiness, high yield, low production cost and less waste discharge and is an environment-friendly production process.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a preparation method of 2,4,6-trichlorophenylhydrazine. Background technique [0002] 2,4,6-Trichlorophenylhydrazine is a white crystalline powder, soluble in alcohol, ketone and other solvents, slightly soluble in water, with a melting point of 142-143°C. 2,4,6-Trichlorophenylhydrazine is an important intermediate in organic synthesis, mainly used in medicine, pesticide, dyestuff and other fields. [0003] At present, the preparation methods of 2,4,6-trichlorophenylhydrazine cannot avoid operations such as diazotization, reduction, acidification, and alkali analysis of 2,4,6-trichloroaniline, and these operations have higher requirements on reaction temperature. , diazotization must be a low-temperature reaction, and if the rate of addition of sodium nitrite solution and the degree of reaction are not well controlled, side reactions will occur and lead to...

Claims

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Application Information

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IPC IPC(8): C07C241/02C07C243/22
CPCC07C241/02C07C243/22
Inventor 李博强
Owner 李博强