Preparation method of 3-nitrophenylhydrazine hydrochloride_Kain Industrial Additive

Background and overview^[1][2]

3-Nitrophenylhydrazine hydrochloride is an aromatic organic compound and an important pharmaceutical intermediate. The existing technology uses m-nitroaniline as raw material, undergoes diazotization reaction, sodium sulfite reduction, hydrolysis, and salt formation to prepare the hydrochloride of m-nitrophenylhydrazine. The reaction time is long, and the generally required yield is only 63-72%, and the production cost is high.

Structure

Preparation method^[1-2]

A method for preparing 3-nitrophenylhydrazine hydrochloride, which uses m-nitroaniline as a starting material, undergoes diazotization reaction, reduction reaction, and hydrolysis to prepare m-nitrophenylhydrazine, which is formed with hydrochloric acid. The salt is obtained to obtain 3-nitrophenylhydrazine hydrochloride. The reduction reaction uses sodium metabisulfite as the reducing agent at 10-35°C and a pH of 7-9. The temperature of the reduction reaction is preferably 20°C, and the pH is preferably 7. The specific steps are as follows:

1) Add 110ml of water to an 800ml beaker, stir, add 126.5ml of 10N hydrochloric acid and 60g of m-nitroaniline, heat to 90°C to dissolve them all, then slowly cool the solution to 0°C, quickly add submersible Sodium nitrate solution (made up of 30 grams of sodium nitrite and 15 ml of water) is added. Adjust the pH of the system to 1-2. Control the temperature of the reaction system to 5°C-7°C. After 30 minutes of reaction, stop the reaction, filter and keep it. filtrate.

2) Add 250ml of water to a 2000ml beaker, add 128g of sodium metabisulfite and 143g of sodium hydroxide while stirring. At this time, the pH of the solution is 7 and the temperature of the solution is 35°C. After the solution cools to 18°C, slowly Add the above filtrate. When the addition is complete, the solution temperature is 20°C and the pH is 7. Continue the reaction for 30 minutes. Warm the reaction system to 30-40°C, stir, add 80.5ml of hydrochloric acid, continue to heat to 75-80°C, and After reacting at this temperature for 1.5-2 hours, 40 grams of sodium chloride was added, the system was cooled to 20°C, filtered to retain the filter cake and dried to obtain the product. The purity measured by high performance liquid chromatography was 98.42%.