A kind of 2-methyl-5 nitroimidazole production technology

Abstract

The invention discloses a process for producing 2-methyl-5-nitroimidazole. The process comprises the following steps: (1) a nitration reaction, (2) neutralization and centrifugation, and (3) drying and packaging, wherein the step (2) further comprises a process for recovering ammonium sulfate from wastewater, and the process comprises the steps of adding the wastewater into a tri-effect evaporating crystallizer for mother liquor concentrating, carrying out crystallization to obtain ammonium sulfate, separating out ammonium sulfate crystals through a horizontal type spiral centrifuge, and carrying out drying by an air-flow dryer, thereby obtaining finished ammonium sulfate. According to the process, ammonia water is used for neutralizing a nitration solution, and a neutralization index is easy to accurately control, so that the process is more applicable to large-scale production; single ammonium sulfate is adopted as a catalyzing and stabilizing agent of reaction, the consumption of main materials is not affected, urea is not added, and the production cost is lower; and the single ammonium sulfate is used, thus, the recovery of ammonium sulfate from the wastewater is more facilitated, the product yield reaches 91.2% or more, and the product content reaches 99.7% or more.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a production process of 2-methyl-5-nitroimidazole. Background technique [0002] 2-Methyl-5-nitroimidazole is mainly used in organic synthesis in industry. It is an important intermediate for the synthesis of pharmaceutical raw materials metronidazole, secnidazole, and veterinary drug damexol. 2-methylimidazole is mostly used in industry As raw material, in concentrated sulfuric acid medium, concentrated nitric acid is added dropwise at high temperature for nitration reaction. Due to directly reacting with mixed acid, a large amount of nitrogen dioxide will come out, and the product yield is low. In the prior art, a mixture of urea and ammonium sulfate is added as a catalyst and stabilizer for the reaction, a mixture of nitric acid, urea and ammonium sulfate is added to 2-methylimidazole, then concentrated sulfuric acid is added dropwise at elevated temperature, and th...

AI Technical Summary

Problems solved by technology

Due to the direct reaction with mixed acid, a large amount of nitrogen dioxide will emerge, and the product yield is low

In the prior art, a mixture of urea and ammonium sulfate is added as a catalyst and stabilizer for the reaction, a mixture of nitric acid, urea and ammonium sulfate is added to 2-methylimidazole, then concentrated sulfuric acid is added dropwise at elevated temperature, and then nitric acid and sulfuric acid are added to form The mixed acid, finally adjust pH with sodium hydroxide to neutralize the nitration solution, obtain 2-methyl-5 nitroimidazole after filtration, can eliminate smog and improve product yield, there are following disadvantages in the actual operation process of this method: 1 ) Use sodium hydroxide for neutralization, because its alkalinity is too strong, the neutralization index is difficult to accurately control, and the neutralization end point is: pH=4.0-5.0, which is not suitable for large-scale production; 2) Use a mixture of urea and ammonium sulfate as Catalyst and stabilizer for the reaction, the production cost is high, and it is not convenient for material management in industrialization; 3) Urea is easy to decompose during the reaction process and cannot be recycled reasonably