Separation and purification of 4-hydroxy-3-nitropyridine by sublimation method

Abstract

The invention relates to the technical field of preparation of medicinal intermediate, which comprises the following steps: heating 95.0 to 98.6 percent of 4-hydroxy-3-nitropyridine crude product in which inorganic salt accounts for less than or equal to 18.8 percent in percentage by mass under pressure reduction of a mechanical vacuum pump to sublimate the 4-hydroxy-3-nitropyridine so as to obtain a sublimated product, wherein the sublimated product is the purified 4-hydroxy-3-nitropyridine without the inorganic salt; measuring the sublimated product through efficient liquid chromatography, and purifying the crude 4-hydroxy-3-nitropyridine to more than 98 percent from 95.0 percent in percentage by mass with the yield of more than 95 percent; and under normal pressure (atmosphere), heating the sublimated product to sublimate the 4-hydroxy-3-nitropyridine so as to obtain a sublimated and purified product of more than 99.7 percent 4-hydroxy-3-nitropyridine in percentage by mass without the inorganic salt. Compared with a wet separation method, the invention has high yield and low energy consumption, does not produce wastewater, and has social and economical effects.

Description

technical field [0001] The invention relates to the technical field of preparation of pharmaceutical intermediates, in particular to the separation and purification of 4-hydroxy-3-nitropyridine by a sublimation method. Wastewater has both social and economic benefits. Background technique [0002] Pyridine and its derivatives are important intermediates for the synthesis of heterocyclic compounds, pesticides and medicines. The compounds obtained after replacing the benzene ring with a pyridine ring often have higher biological activity or lower toxicity. In recent years, people have used various heterocycles, especially pyridine groups, to replace the benzene rings in the molecular structure of existing species or to introduce other groups into known pyridine group-containing molecules for derivatization, in order to obtain new active compounds . The nitration reaction is an important means to obtain the two nitrogen-containing functional groups of nitro and amino, and is...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a process for separating and purifying 4-hydroxy-3-nitropyridine, so as to overcome the shortcomings of the prior art, such as low efficiency, low yield, high energy consumption, and environmental pollution.