Preparation method for 2-bromophenylhydrazine

Abstract

The present invention relates to preparation process of 2-bromo phenyl hydrazine. The compound 2-bromo phenyl hydrazine is prepared with 2-bromo aniline as initial material, and through diazo reaction, reduction reaction and hydrolysis. The reduction reaction has sodium pyrosulfite as the reductant and the reaction conditions of 10-35 deg.c temperature and pH 7-9. The 2-bromo phenyl hydrazine preparing process has high product purity and low production cost.

Description

Technical field

[0001] The invention relates to a preparation method of 2-bromophenylhydrazine. Background technique

[0002] 2-Bromophenylhydrazine is an important intermediate, especially a pharmaceutical intermediate. The existing technology uses 2-bromoaniline as raw material, and prepares 2-bromobenzene through diazotization reaction, sodium sulfite reduction and hydrolysis. The synthesis method of hydrazine requires a long reaction time, generally requires a yield of only 63-72%, and has high production costs. Contents of the invention

[0003] The technical problem to be solved by the present invention is to provide a preparation method of 2-bromophenylhydrazine. The 2-bromophenylhydrazine product obtained by this method has high purity and low production cost.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for preparing 2-bromophenylhydrazine, which uses 2-bromoaniline as ...

Examples

Embodiment Construction

[0008] The specific implementation of the present invention will be described below:

[0009] Add 150ml of water to an 800ml beaker, stir, add 57.5ml of 10N hydrochloric acid and 34.6g of 2-bromoaniline, warm to 80℃ to completely dissolve the 2-bromoaniline, cool to below 0℃, and slowly add sodium nitrite solution (It is made up of 15 grams of sodium nitrite and 30 grams of water). After reacting for 20 minutes, filter and retain the filtrate.

[0010] Add 200ml of water to a 1000ml beaker, add 64g of sodium metabisulfite and 65g of sodium hydroxide under stirring, stir until all dissolved and then cool to 15℃, slowly add the above filtrate, the pH of the solution is 7 and the temperature of the solution is 18 After 30 minutes of reaction, the temperature was raised to 80°C, 143.7ml of 10N hydrochloric acid was added, and the temperature was raised to 97-100°C. After reacting at this temperature for 30 minutes, 6 grams of activated carbon was added. After decolorization, it was fi...

Technical field

[0001] The invention relates to a preparation method of 2-bromophenylhydrazine. Background technique

[0002] 2-Bromophenylhydrazine is an important intermediate, especially a pharmaceutical intermediate. The existing technology uses 2-bromoaniline as raw material, and prepares 2-bromobenzene through diazotization reaction, sodium sulfite reduction and hydrolysis. The synthesis method of hydrazine requires a long reaction time, generally requires a yield of only 63-72%, and has high production costs. Contents of the invention

[0003] The technical problem to be solved by the present invention is to provide a preparation method of 2-bromophenylhydrazine. The 2-bromophenylhydrazine product obtained by this method has high purity and low production cost.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for preparing 2-bromophenylhydrazine, which uses 2-bromoaniline as ...

Examples

Embodiment Construction

[0008] The specific implementation of the present invention will be described below:

[0009] Add 150ml of water to an 800ml beaker, stir, add 57.5ml of 10N hydrochloric acid and 34.6g of 2-bromoaniline, warm to 80℃ to completely dissolve the 2-bromoaniline, cool to below 0℃, and slowly add sodium nitrite solution (It is made up of 15 grams of sodium nitrite and 30 grams of water). After reacting for 20 minutes, filter and retain the filtrate.

[0010] Add 200ml of water to a 1000ml beaker, add 64g of sodium metabisulfite and 65g of sodium hydroxide under stirring, stir until all dissolved and then cool to 15℃, slowly add the above filtrate, the pH of the solution is 7 and the temperature of the solution is 18 After 30 minutes of reaction, the temperature was raised to 80°C, 143.7ml of 10N hydrochloric acid was added, and the temperature was raised to 97-100°C. After reacting at this temperature for 30 minutes, 6 grams of activated carbon was added. After decolorization, it was fi...