CS214537B1 - Process for preparing 4-amino-4H-1,2,4-triazole - Google Patents

Abstract

The production of 4-amino-4H-1,2,4-triazole is based on the reaction of hydrazine and formamide of the general formula I, where R^ and Rg denote hydrogen or alkyl with up to four members. A mixture of hydrazine and formamides of the formula I in a molar ratio of 10 «1 /*1 H-g-N (I) 0 r2 to 1 : 10, preferably in a ratio of 1 to 1, is heated up to 230 °C, preferably at a temperature of 160 to 180 °C, with simultaneous removal of water and released amine or ammonia. The removal of water and amine can also be influenced by changing the pressure in the range of 0.1 to 500 kPa. The yields of the reaction, especially the reaction of formamides with hydrazine, are higher than 95% of theory. The reaction time is in the range of 1.5 to 4 hours.

Description

The invention relates to a process for the preparation of N-amino-1H-1,2,4-triazole from formamides and hydrazine as starting materials.

The formation of 4-amino-4H-1,2,4-triazole in the processes described hitherto is based on the reaction of ethylsulfonyl. Rydrazine (see Organic Syathesis, Ooll. Vol. III, p. 96, J. Willey,

New York 1356 ?. The preparation process is divided into two stages. In the first step, the ethyl formate and the alcohol are reacted in an alcoholic medium for 16-20 hours to form the formhydrazide which is isolated by evaporation of the solvent. In the second step, the formhydrazide is gradually heated to 160-180 ° C for three to four hours while distilling off the water evolved. If the time required to isolate the formhydrazide from the reaction mixture of the first stage reaction is omitted, the total reaction time exceeds 20 hours. This excessively long reaction time substantially affects the capacity of the production equipment. Therefore, methods are sought which substantially reduce the reaction time.

It has now been found that a substantial reduction in reaction time occurs when formamide and its N-alkyl derivatives are used in admixture with hydraminam instead of ethylphonate.

The nature of the process for preparing 4-amino-4H-1,2,4-triazole is that a mixture of formamides of formula I

HCN Λ ^ ^R 2 wherein R ₁ and SG stands for a hydrogen or alkyl of one to four carbon atoms, and hydrazine in a ratio of 10 mďLárním and 1-1: 10, most preferably in a ratio of 1 to 1, heated from room temperature to no. at a temperature of 230 ° C, preferably at a temperature of 160 to 180 ° C, with simultaneous removal of water and the reaction of liberated amine or ammonia, wherein the removal of both water and liberated amine or ammonia is accelerated by a pressure change of 0.1-500 kPa.

The reaction of formamides and hydrazine can be expressed by the following equation

HCS-NH- - NH -> HC-NH-NH | i \ 2 2 B ² + x * HN i (a)

R "

R,

HO-NH-NHII ²⁰

N

II

-> H-O ^{+ 2H} 2 ° N <b>

The ease of reaction of the formamides of the formula I with hydrazine is dependent on the R ^ and Rg groups. Ν, Ν-Dialkylformamides (both R ₁ and R 8 are alkyl with up to four carbons) react slowly. The reaction rate can be increased either by a large excess of hydrazine or by an elevated temperature. However, the temperature is limited by the volatility of N, N-dialkyl chloride. N-Monoalkylformamides react with hydrazine under milder conditions. Removal of amine liberation reactions can be accelerated not only by elevated temperature, but also by reducing apparatus pressure. Unsubstituted formamide reacts most easily with hydrazine. After mixing the starting materials at room temperature, ammonia is released. The formation of ammonia can be accelerated by elevated temperature, e.g. at 80 ° C, development is complete within 15 minutes. The amine or ammonia released by the reaction can be absorbed and used for other purposes. '

As the source of hydrazine, not only anhydrous hydrazine, but also its solutions in conventional polar solvents can be used. However, it is preferred to use readily available aqueous hydrazine solutions, supplied as hydrazine hydrate solutions or hydrazine hydroxides having different hydrasine contents. Pormamides of the formula I are perfectly miscible with hydrazine solutions. If too dilute hydrazine solutions are used to prepare 4-amino-4H-1,2,4-triazole, it is preferred, after mixing the materials, to raise the temperature while lowering the apparatus pressure and to accelerate the evaporation of excess solvent, especially water. The resulting concentrate, which contains predominantly formhydrazide, can be converted to 4-amino-4H-1,2,4-triazole by gradually increasing the temperature.

An advantage of the above process for the preparation of 4-amino-4H-1,2,4-triazole is that the reaction time compared to the original process in which ethyl formate was used as the starting material is reduced by more than 75%, the entire preparation being in a simple production facility.

4-Amino-4H-1,2,4-triazole is used as a basic raw material for the production of pharmaceuticals 1 pesticides, light-colored dyes and some types of fibers and resins with reduced flammability. It is also used as an inhibitor of nitrification of some types of nitrogen fertilizers.

The following examples illustrate the convenience of preparing 4-amino-4H-1,2,4-triazole according to the invention.

- Example 1

110 wt. parts of Ν, Ν-dimethylformamide and 200 parts of a 30% aqueous hydrazine solution were heated to 50 ° C at 50 psi for one hour. Under these conditions, the bulk of the water and the re-liberation of the dimethylamine released are distilled off. The residue is gradually heated at atmospheric pressure to 160-180 ° C and held at these temperatures for two hours. The resulting melt was cooled and solidified to 50 parts by white solid after inoculation. Chromatographic analysis showed that it contained 95% 4-amino-4H-1,2,4-triazole. The overall yield is 75.5%.

Example 2

K 91.0 wt. 63.5% by weight of d-butylformamide at 80 DEG C. are added. of a 50.5% aqueous hydrazine solution (80% hydrazine hydrate). The mixture boils gently with 1-aminobutane released, which can be removed by heating to 90-100 ° at 8.0 kPa. The resulting syrup-like solution is further heated at atmospheric pressure to 170-180 ° C for 1.5-2 hours. A melt (41.5 parts by weight) is obtained which contains 96% 4-amino-4H-1,2,4-triazole. The total yield of the reaction was 95.0% of theory.

Example 3

Ke 100 wt. 90 parts of foxmamide are added at 80 DEG C. to the parts of the 64% aqueous hydrazine solution (100% hydrazine hydrate) as rapidly as the absorber is capable of absorbing the ammonia released. By raising the temperature to 100 ° C, the last ammonia residue is displaced and the mixture is further heated to 170-180 ° C for one hour while distilling off the water. A product having a pour point of 75-80 ° C is obtained. Analysis found to contain 93 to 96%

Of 4-amino-4H-1,2,4-triazole in a yield of 95-98% of theory.

Claims (1)

Process for the preparation of 4-amino-4H-1,2,4-triazole, characterized in that the mixture of formamides of the general formula I II \ ^{0 R} 2 * where R. | and R ₂ znaěí hydrogen or alkyl of one to four carbon atoms, and hydrazine in a molar ratio of 10 j 1 to 1: 10, most preferably in a ratio of 1> 1 gradually heated from room temperature to. to a temperature of 230 ° C, preferably at a temperature of 160 to 180 ° C, with simultaneous removal of water and reaction of the liberated amine or ammonia, wherein the removal of water, amine and ammonia is accelerated by changing the pressure between 0.1 and 500 kPa. AND I w »WB« »ee FIXED DESCRIPTION OF THE INVENTION TO COPYRIGHT CERTIFICATE 214 214 Int. Cl- ³ C 07 D 24S / 08 In the description of the invention for the author's certificate No. 214 537, page 1, which belongs to the description of the invention AO 214 516 and vice versa, was accidentally printed.