Preparation method of 4-methyl phenylhydrazine hydrochloride

A technology of methylphenylhydrazine and hydrochloride, which is applied in the field of preparation of organic compounds, can solve the problems of high impurity content, poor stability, and small output of products, and achieve the effects of improving purity, easy operation, and less impurities

Inactive Publication Date: 2018-03-20
TIANJIN CHEM REAGENT RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

And the product obtained by the preparation method of existing 4-methylphenylhydrazine hydrochloride has high impurity content, low purity, poor stability, and small output, which cannot meet the needs of the market

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A preparation method for 4-methylphenylhydrazine hydrochloride, comprising the following steps:

[0019] ⑴ diazotization

[0020] Add 50g of 4-methylaniline and 150ml of 37% concentrated hydrochloric acid into a 1L three-necked flask, cool to 2°C with ice salt, add 85.7g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature at 2°C for 1 hour.

[0021] ⑵ reduction

[0022] Add 450ml of 37% concentrated hydrochloric acid, 450ml of water and 120g of zinc powder in the reaction solution, keep the temperature at 18°C ​​and react until the reaction is complete, the reaction solution becomes off-white, then add 20% sodium hydroxide solution until the pH value of the reaction solution is 10, After 1 hour of heat preservation at 5°C, crystals were precipitated, and 26.9 g of crude 4-methylphenylhydrazine was obtained by filtration.

[0023] ⑶ Purification

[0024] Dissolve 26.9g of crude 4-methylphenylhydrazine in 538g of water, heat to 60°C to disso...

Embodiment 2

[0028] A preparation method for 4-methylphenylhydrazine hydrochloride, comprising the following steps:

[0029] ⑴ diazotization

[0030] Add 200g of 4-methylaniline and 600ml of 37% concentrated hydrochloric acid into a 5L three-necked flask, cool to 2°C with ice salt, add 343g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature at 2°C for 1.5 hours.

[0031] ⑵ reduction

[0032] Add 730ml of 37% concentrated hydrochloric acid, 730ml of water and 195g of zinc powder to the reaction solution, keep the temperature at 18°C ​​until the reaction is complete, the reaction solution turns off-white, then add 25% sodium hydroxide solution until the pH value of the reaction solution is 10 , kept at 5°C for 1.5 hours, crystals were precipitated, and 119g of crude 4-methylphenylhydrazine was obtained by filtration.

[0033] ⑶ Purification

[0034] Dissolve 119g of crude 4-methylphenylhydrazine in 2380g of water, heat to 60°C to dissolve it completely, then a...

Embodiment 3

[0038] A preparation method for 4-methylphenylhydrazine hydrochloride, comprising the following steps:

[0039] ⑴ diazotization

[0040] Add 500g of 4-methylaniline and 1500ml of 37% concentrated hydrochloric acid into a 10L three-necked flask, cool to 2°C with ice salt, add 857g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature between 0 and 5°C for 1.5 Hour.

[0041] ⑵ reduction

[0042] Add 730ml of 37% concentrated hydrochloric acid, 730ml of water and 480g of zinc powder to the reaction solution, keep the temperature at 18°C ​​until the reaction is complete, the reaction solution turns off-white, then add 30% sodium hydroxide solution until the pH value of the reaction solution is 10 , kept at 5°C for 2 hours, crystals were precipitated, and 292 g of crude 4-methylphenylhydrazine was obtained by filtration.

[0043] ⑶ Purification

[0044] Dissolve 292g of crude 4-methylphenylhydrazine in 5840g of water, heat to 60°C to dissolve it comple...

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PUM

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Abstract

The invention relates to a preparation method of 4-methylphenylhydrazine hydrochloride, comprising the steps of diazotization, reduction, purification and salt formation. In the steps of diazotization and reduction, concentrated hydrochloric acid is used to keep the reaction solution in strong acidity, so as to ensure the smooth and complete progress of the reaction. In the reduction step, zinc powder-concentrated hydrochloric acid is used as the reducing agent instead of sodium thiosulfate, sodium bisulfite, stannous chloride-hydrochloric acid, etc., which not only has good reduction performance, high yield, shortens the reaction time, and generates Impurities such as zinc hydroxide are easy to remove, so that the product has less impurities and high purity. Washing with acetone in the salt-forming step not only improves the purity of the product, but also ensures the appearance of the product. The preparation method has a stable and reliable process, is easy to operate, has high product purity (the content measured by high performance liquid chromatography is more than 99%), and the yield is more than 39%, which fully meets the market demand for 4-methylphenylhydrazine hydrochloride.

Description

technical field [0001] The invention relates to the technical field of preparation of organic compounds, in particular to a preparation method of 4-methylphenylhydrazine hydrochloride. Background technique [0002] As an important intermediate in organic synthesis, 4-methylphenylhydrazine hydrochloride is widely used in the dye and pharmaceutical manufacturing industries, and has a broad market prospect. And the prepared product of existing 4-methylphenylhydrazine hydrochloride has high impurity content, low purity, poor stability and small output, which cannot meet the needs of the market. Contents of the invention [0003] The purpose of the invention is to overcome the deficiencies in the prior art, and provide a preparation method of 4-methylphenylhydrazine hydrochloride with high purity, large output and good stability. [0004] In order to achieve the above object, the present invention adopts the following technical solutions: [0005] A preparation method of 4-me...

Claims

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Application Information

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IPC IPC(8): C07C241/02C07C243/22C07C245/20
CPCC07C241/02C07C245/20C07C243/22
Inventor 申倩
Owner TIANJIN CHEM REAGENT RES INST
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