Preparation method for 3-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 3-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 3-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0019] ⑴ diazotization

[0020] Add 50g of 3-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 26.6 g of crude 3-fluorophenylhydrazine was obtained by filtration.

[0023] ⑶ Purification

[0024] Dissolve 26.6g of crude 3-fluorophenylhydrazine in 532g of water, heat to 60°C to disso...

Embodiment 2

[0028] A preparation method for 3-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0029] ⑴ diazotization

[0030] Add 200g of 3-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 122 g of crude 3-fluorophenylhydrazine was obtained by filtration.

[0033] ⑶ Purification

[0034] Dissolve 122g of crude 3-fluorophenylhydrazine in 2440g of water, heat to 60°C to dissolve it completely, then ...

Embodiment 3

[0038] A preparation method for 3-fluorophenylhydrazine hydrochloride, comprising the following steps:

[0039] ⑴ diazotization

[0040] Add 500g of 3-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 288g of crude 3-fluorophenylhydrazine was obtained by filtration.

[0043] ⑶ Purification

[0044] Dissolve 288g of crude 3-fluorophenylhydrazine in 5760g of water, heat to 60°C to dissolve it comp...

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PUM

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Abstract

The invention relates to a preparation method for 3-fluorophenylhydrazine hydrochloride. The preparation method comprises the following steps: diazotization, reduction, purification and salt formation. During diazotization and reduction, concentrated hydrochloric acid enables a reaction solution to maintain highly acidic, so smooth and complete reaction is guaranteed. In the step of reduction, zinc dust-concentrated hydrochloric acid is used as a reducing agent to replace sodium hyposulfite, sodium bisulfate, stannous chloride-hydrochloric acid, etc., and the zinc dust-concentrated hydrochloric acid is good in reducing property and high in yield, shortens reaction time, enables impurities like zinc hydroxide produced after the reaction to be easy to remove and allows produced 3-fluorophenylhydrazine hydrochloride to be low in impurity content and high in purity. In the step of salt formation, acetone is used for leaching, so product purity is improved and product appearance is guaranteed. The preparation method is stable and reliable in process and easy to operate; and produced 3-fluorophenylhydrazine hydrochloride is high in purity (no less than 99% according to the results of content measurement via high performance liquid chromatography), has a yield of no less than 39% and completely meets market demands for 3-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 3-fluorophenylhydrazine hydrochloride. Background technique [0002] As an important intermediate in organic synthesis, 3-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 3-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 3-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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IPC IPC(8): C07C243/22C07C241/02
Inventor 何金
Owner TIANJIN CHEM REAGENT RES INST
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