SU1703645A1 - Method for preparation of 2,6-diamino-3,5-dinitropyrazine and 2-methoxy-6-chloro-3,5-dinitropyrazane as intermediate products for synthesis of 2,6-diamino-3,5-dinitropyrazine - Google Patents

Abstract

The invention relates to heterocyclic substances, in particular the preparation of 2,6-diamino-3,5-dinitropyraine for the synthesis of heat-resistant polymers and 2-methoxy-6 chloro-3, 5-dinitropyrazan, an intermediate product for the preparation of the first substance. The purpose of the invention is to increase the yield of the target product and simplify the process. He lead the reaction of 2-methoxy-6-chloropyrazine with a nitrous mixture - conc. NGUz and 20-25% oleum with their mass ratio of 1: (1.5-3) :( 8-14) at 30-50 ° C, followed by holding the reaction mass at 40-45 ° amp; C for 0.5 hours and then at 70-90 ° C for 2-4 hours. The resulting intermediate, 2-methoxy-6-chloro-3,5-dinitropirazine, is subjected to ammonolysis with an aqueous NHR at 40-60 & ° C in a water-miscible solvent — acetonitrile, dioxane, methanol, acetone, or tetrahydrofuran. Exit after nitration 77%. m.p. 105.5-10b.5 ° C. Output after ammonolysis 98%, so pl. 350 ° C. In comparison with the known yield of the target product is increased from 25 to 77% with a decrease in the number of stages. 2 sp.f-ly, 2 tables.

Description

The invention relates to nitrogen-containing heterocycles, in particular, to an improved method for the preparation of 2,6-diamino-3,5-dinitropyresin of the formula

N

  i i j

(I)

H2N N NH2 N02

OoN

N

which is used to synthesize particularly heat-resistant polymers, as well as to a novel pyrazine-2-methoxy-b-chloro-3,5-dinitropyrazine derivative of the formula

Cl N OSI,

Xx

OzNbTNOj

Vj

ABOUT

SA)

& ate

as an intermediate for the synthesis of 2,6-diamino-3,5-dinitropyrazine,

A known method of producing compound (I) by ammonolysis of the starting tetracyanopyrazine with liquid ammonia at a temperature of -35 ° C in tetrahydrofuran, hydrolysis of the resulting 2,6-diamino-3,5-dicyanopyrazine 5% NaOH for 6 days with

by subsequent nitrating of the intermediate 2, b-diamino-3,5-pyrazine-diconic acid with a sulfur-nitrogen mixture in a total yield of 25%.

The disadvantages of this method are its multistage, the need for the amination step at low temperatures, the duration of the hydrolysis step, the complexity of the synthesis of the starting tetracyanpyrazine.

The aim of the invention is to simplify the process and increase the yield of 2,6-diamino-3,5-dinitropyrazine.

The goal is achieved by the fact that 2-methoxy-b-chloropyraein is subjected to nitration with a mixture of concentrated nitric acid and 20-25% oleum at 3 (L50 ° C and at a mass ratio of 2-methoxy-6-chlorine-erase: concentrated nitric acid: Oleum, equal to 1: 1.5-3.0: 8.0-14, holding the reaction mass at 40-45 ° С for 0.5 h and then at 70-90 ° С for 2.0-4 , 0 h, followed by ammonolysis of the isolated intermediate 2-methoxy-6-chloro-3,5-dinitropyrazine with a concentrated aqueous solution of ammonia in an environment of a water-miscible organic solvent, such as to acetonitrile, methanol, dioxane, tetrahydrofuran, acetone, at 40-60 ° C.

EXAMPLE 1. 2-methoxy-b-chloro-3,5-dinitropyrazine.

To a mixture of 10.3 ml (0.22 M) of 98% HN03 and 36 ml (68 g) of 20% oleum, with strong stirring and cooling with cold water, 8.4 g (0.06 M) were added. 2-methoxy-6-chloropyrazine so that the temperature is maintained in the range of 35-40 ° C. Stir for 0.5 h at 40-45 ° C, and then 3.5 h at 75-80 ° C, cool, pour out ice, filter the precipitate, rinse with ice water until neutral, and dry. Weight 10.2 g (77%).

The product is recrystallized from alcohol to remove traces of acids. Mp. 105.5-106.5 ° C.

HMR spectrum: 4.25 s (OCH3).

Mass spectrum: m / e 234 (M +); 188 (M + - —N02).

Calculated,%: 025.60: H 1.28: N 23.87. Found:% 25.31: H1.37: N 23.55.

Table 1 shows the data on nitration of 2-methoxy-6-chloropyrazine as in Example 1 under various conditions.

PRI mme R 2. 2,6-diamino-3,5-dinitropyrazine,

To a solution of 2.34 g (0.01 M) of 2-methoxy-6-chloro-3,5-dinitropyrazine in 25 ml of acetonitrile at 40-45 ° C, 9 ml of a 25% aqueous solution of ammonia are poured, stirred at 60 ° 40 minutes, cool filtered. The precipitate is washed with acetonitrile, then with methanol and air dried. Weight 1.96 g (98%). M.p. 350 ° C.

IR spectrum, cm 1: 1340: 1560 (N02): 3260 (NH2); 880: 1060; 1220.

Mass Spectrum: m / e 200 (M4),

Calculated,%: C 24.00; H 2.00; N 42.00.

Found,%: C 24.36; H 1.96; N 41.82.

The results of the reaction of the ammonia- lysis of 2-methoxy-6-chloro-3,5-dinitropyrasine in other water-miscible organic solvents are listed in Table 2.

The overall yield (I) based on the starting 2-methoxy-6-chloropyrazine is 52-75%.

Thus, the proposed method allows to increase the yield of the target product to 52-75% against 25% by a known method and, in addition, to simplify the process of obtaining by reducing the number of stages, conducting the amination stage with aqueous ammonia at 40-60 ° C instead of anhydrous liquid ammonia at 15 ° C. a significant reduction in total process time and the use of a much more affordable starting 2-methoxy-6-chloropyrazine,

Claims (1)

Claims 1. A method of producing 2,6-diamino-3.5-dinitropyrazine from a pyrazine derivative, comprising a step of ammonolysis in an organic solvent medium and a step of treating with a nitrating mixture containing nitric acid and sulfuric acid, in order to simplify the process and increase the yield target product, 2-methoxy-6-chloro-piraein is used as a pyrazine derivative, a mixture of concentrated nitric acid and 20-25% oleum are used as the nitrating mixture, and the organic solvent at the stage onolysis is a water-miscible organic solvent, such as acetonitrile, dioxane, methanol, acetone, or tetrahydrofuran, and the process is carried out by treating pyrazine derivative with a nitrating mixture in a 2: methoxy-b-chloropyrazine: concentrated nitric acid: oleum ratio equal to 1: (1.5-3) :( 8-14), at 30-50 ° C, followed by holding the reaction mass at 40-45 ° C for 0.5 h and then for 2-4 h , and ammonolysis of the obtained intermediate 2-methoxy-6-chloro-3,5-dinitropyrazine with aqueous ammonia at. 2. 2-Methoxy-6-chloro-3,5-dinitropyrazine formula C1 N OCH3  Ш2 as an intermediate for the synthesis of 2,6-diamino-3,5-dinitropyrazine. Table 1 table 2