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Preparation method of 2-fluorophenylhydrazine hydrochloride

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

Inactive Publication Date: 2017-03-22
TIANJIN CHEM REAGENT RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

And the prepared product of existing 2-fluorophenylhydrazine 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 2-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0019] ⑴ diazotization

[0020] Add 50g of 2-fluoroaniline 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 26.8 g of crude 2-fluorophenylhydrazine was obtained by filtration.

[0023] ⑶ Purification

[0024] Dissolve 26.8g of crude 2-fluorophenylhydrazine in 536g of water, heat to 60°C to disso...

Embodiment 2

[0028] A preparation method for 2-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0029] ⑴ diazotization

[0030] Add 200g of 2-fluoroaniline 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 120 g of crude 2-fluorophenylhydrazine was obtained by filtration.

[0033] ⑶ Purification

[0034] Dissolve 120g of crude 2-fluorophenylhydrazine in 2400g of water, heat to 60°C to dissolve it completely, then ...

Embodiment 3

[0038] A preparation method for 2-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0039] ⑴ diazotization

[0040] Add 500g of 2-fluoroaniline 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 hours .

[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 290 g of crude 2-fluorophenylhydrazine was obtained by filtration.

[0043] ⑶ Purification

[0044] Dissolve 290g of crude 2-fluorophenylhydrazine in 5800g of water, heat to 60°C to dissolve it comp...

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Abstract

The invention relates to a preparation method of 2-fluorophenylhydrazine hydrochloride, and the method comprises the steps of diazotization, reduction, purification, and salt forming. In the steps of diazotization and reduction, concentrated hydrochloric acid keeps high acidity of a reaction solution, and smooth and complete performing of the reaction is guaranteed. In a reduction step, zinc dust-concentrated hydrochloric acid is used as a reducing agent, in order to replace sodium hyposulfite, sodium bisulfate, stannous chloride-hydrochloric acid, and the like, and the reducing agent has the advantages of good reduction performance, high yield, shortened reaction time, zinc hydroxide and other impurities which are generated after reaction are convenient to remove, low product impurity, and high purity. In the salt forming step, acetone is used for leaching, purity of the product is improved, and appearance of the product is guaranteed. The preparation method has the advantages of stable and reliable technology, easy operation, high product purity (content which is detected by high performance liquid chromatography is higher or equal to 99%), yield is higher or equal to 39%, and the method can completely satisfy needs of the market on 2-fluorophenylhydrazine hydrochloride.

Description

technical field [0001] The invention relates to the technical field of preparation of organic compounds, in particular to a preparation method of 2-fluorophenylhydrazine hydrochloride. Background technique [0002] As an important intermediate in organic synthesis, 2-fluorophenylhydrazine hydrochloride is widely used in the dye and pharmaceutical manufacturing industries, and has a broad market prospect. However, the product obtained by the existing preparation method of 2-fluorophenylhydrazine 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 present invention is to overcome the deficiencies of the prior art and provide a method for preparing 2-fluorophenylhydrazine 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: ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C243/22C07C241/02
Inventor 何金
Owner TIANJIN CHEM REAGENT RES INST
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