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Preparation method of 2-bromophenylhydrazine hydrochloride

A technology of bromophenylhydrazine hydrochloride and bromophenylhydrazine, which is applied in the field of preparation of 2-bromophenylhydrazine hydrochloride, can solve the problems of high impurity content, poor stability, small output and the like in the product, and achieves improved purity and easy operation. , the effect of less impurities

Inactive Publication Date: 2013-11-13
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 2-bromophenylhydrazine 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-bromophenylhydrazine hydrochloride, comprising the following steps:

[0019] ⑴ diazotization

[0020] Add 50g of 2-bromoaniline and 150ml of 37% concentrated hydrochloric acid into a 1L three-necked flask, cool to 2°C with ice salt, add 65g 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 to the reaction solution, keep the temperature at 18°C ​​until the reaction is complete, the reaction solution turns 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 g of crude 2-bromophenylhydrazine was obtained by filtration.

[0023] ⑶ Purification

[0024] Dissolve 26g of crude 2-bromophenylhydrazine in 520g of water, heat to 60°C to dissolve it completely, the...

Embodiment 2

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

[0029] ⑴ diazotization

[0030] Add 200g of 2-bromoaniline and 600ml of 37% concentrated hydrochloric acid into a 5L three-necked flask, cool to 2°C with ice salt, add 270g 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 115g of crude 2-bromophenylhydrazine was obtained by filtration.

[0033] ⑶ Purification

[0034] Dissolve 115g of crude 2-bromophenylhydrazine in 2300g of water, heat to 60°C to dissolve it completely, then add a...

Embodiment 3

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

[0039] ⑴ diazotization

[0040] Add 500g of 2-bromoaniline and 1500ml of 37% concentrated hydrochloric acid into a 10L three-necked flask, cool to 2°C with ice salt, add 650g 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 270 g of crude 2-bromophenylhydrazine was obtained by filtration.

[0043] ⑶ Purification

[0044] Dissolve 270g of crude 2-bromophenylhydrazine in 5400g of water, heat to 60°C to dissolve it completely...

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Abstract

The invention relates to a preparation method of 2-bromophenylhydrazine hydrochloride, and the method comprises steps of diazotization, reduction, purification and salification. In the steps of diazotization and reduction, concentrated hydrochloric acid is used to keep strong acidity of the reaction liquor and further to guarantee smooth and complete proceeding of the reaction. In the reduction step, zinc powder-concentrated hydrochloric acid is used as a reducing agent instead of sodium hyposulfite, sodium bisulfate, stannous chloride-hydrochloric acid and the like, and has good reduction performance; and also the yield is high, reaction time is shortened, impurities such as zinc hydroxide generated after the reaction are easy to remove, so that the product has less impurities and high purity. In the salification step, acetone is employed for leaching, which not only helps to improve purity of the product, but also helps to guarantee appearance of the product. The preparation method has the advantages of being stable and reliable in technology, easy to operate, high in product purity (the content is 99% or more determined by high performance liquid chromatography), and with yield of 38% or more, and completely satisfies requirement of market on 2-bromophenylhydrazine 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-bromophenylhydrazine hydrochloride. Background technique [0002] As an important organic synthesis intermediate, 2-bromophenylhydrazine hydrochloride is widely used in the pharmaceutical manufacturing industry and has broad market prospects. However, the product produced by the existing preparation method of 2-bromophenylhydrazine 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 object of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing 2-bromophenylhydrazine hydrochloride with high purity, large yield and good stability. [0004] In order to achieve the above object, the present invention adopts the following technical solutions: [0005] A preparati...

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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