SU449050A1 - Method for preparing 2-methyl-3-nitro4-methoxymethyl-5-cyano-6-hydroxypyridine - Google Patents

Description

one

The invention relates to an improved P method for the preparation of 2-methyl-3-nitro-4-methoxy-metip-5-cyano-6-oxypyridine, which is an intermediate in

synthesis of vitamin В „. b

A method of producing 2-methyl-Znitro-4-methoxymethyl-5-cyano-6-hydroxypyridine (nitropiridone) is known by nitrating 2-methyl-4-methoxymethyl-5-cyano-6-hydroxy-, neridine (pyridone) with concentrated nitric acid in the environment of acetic angi-: dride in the presence of urea at a temperature of from 0 to 45 ° C, followed by a long incubation at 25 C.

The disadvantages of this method are the duration of the process, as well as the high viscosity of the nitro mass, which makes it difficult

use of the method in industry. In order to eliminate the above

disadvantages / proposed reaction of nitrova-P or carried out at 9O-93 ° C.

The duration of the titration process to the proposed method is reduced by a factor of. At the same time, the viscosity of the nitro mass decreases significantly.

Example. Receiving nitropiridone according to the periodic scheme.

A 45 ml flask equipped with a stirrer, a reflux condenser, a cooling jacket and a thermocouple is charged with 45 ml of a previously prepared suspension of pyridone with urea in acetic anhydride. Then, with continuous stirring and cooling for 8-12 minutes, 5 ml of concentrated nitric acid are poured.

Data on the mode of the nitration process and the parameters of the nitroproduced product are given in Table 1.

Table 1,

The data given in table. 1, it is shown that the nitropyridone obtained by g | ri 9O-93 ° C contains the main substance (not less than nitropyridone obtained at 43-45 s. Weight output of nsp-ropyridone for the proposed temperature-average regime by 1.3 /: higher than for the previously used one. At the same time, the viscosity of the reaction mass is significantly reduced.

11 p m m e p 2. Production of nitropiridone by a continuous scheme.

Automated process of continuous nitriding of pyridone is carried out in the mountains: a classic tubular sectioned

a 10 l reactor with a new type of agitator and a separate cooling jacket for each section. A suspension of pyridone with urea in acetic anhydride and nitric acid is fed to the reactor using ND pump dispensers. The suspension enters the first section of the reactor, and the total amount is consumed by the HNO

ABOUT

distributed into four streams and mislaid into the first four sections of the reactor. The resulting nitromass from the reactor enters the thermal holding apparatus, and then to crystallization and filtration. The test results are shown in Table 2.

table 2

The data given in table. 1 and 2 show that the duration of the nitration process is reduced by almost 2-3 times, which corresponds to an increase in productivity. At the same time, the viscosity of the reaction

mass, improved flow and transportability characteristics. Nitropiridone, obtained by the proposed method, has high quality characteristics (purity 97.297, 8%), its weight output increases by an average of 0.8-1.2; o.

The safety of the process of nitriding pyridone at 9 ° -93 ° C is ensured by the use of an automatic protection system. In the course of studying this process at 9 ° -93 ° C, there was no sign of vyryus of the reaction mass, claps, or explosions.

Subject invention

The method of producing 2-methyl-3-nitro-4-methoxymethyl-5-cyano-6-hydroxypyridine by nitrating 2-methyl-4-methoxy fetiyl-5-cyan-t 6-oxypyridine with concentrated nitric acid in vinegar. of anhydride in the presence of urea, characterized in that, in order to accelerate the process, the nitration reaction is carried out at 90-93 ° C.