FR2875804A1 - PROCESS FOR THE PREPARATION OF 4-AMINO-1,2,4 TRIAZOLE - Google Patents

Abstract

The present invention relates to a process for the preparation of compounds of formula (1): wherein R denotes H or an alkyl group containing from 1 to 10 carbon atoms and which may be substituted by one or more aryl, heteroaryl, hydroxy or alkenyl groups. particularly useful for preparing 4-amino-1,2,4-triazole.It also relates to the compounds derived from said process.

Description

R-C C-R N

  The present invention relates to a process for the preparation of 4-amino-1,2,4 triazole and more particularly to compounds having the following formula: NH 2 (1) ) in which R denotes H or an alkyl group containing from 1 to 10 carbon atoms and which may be substituted with one or more aryl, heteroaryl, hydroxy or alkenyl groups.

  The two Rs can be the same or different. It also relates to the compounds derived from said process.

  The compounds having the general formula (1) are generally prepared by reacting hydrazine with a carboxylic acid R COOH, then distilling off the reaction water and optionally the dilution water of the hydrazine and acid. The final product obtained in molten medium is chipped, that is to say that it is put in contact with a scaling machine on which it cools, solidifies (crystallizes) and is divided into scales. Depending on the final application which is either agrochemical or pharmaceutical, these compounds may be recrystallized in a medium preferably comprising isopropanol.

  The compounds obtained after this recrystallization step are needle-shaped crystals having an average size (length) of the order of 0.05 to 0.2 mm and a width of the order of 0.01 to 0.05 mm. Under this morphology, they have many drawbacks, including a very long drying time, very poor flowability, high hygroscopy and storage mass (caking).

  Another problem encountered is that the compounds of general formula (1) are colored before recrystallization and that a coloration is sometimes persistent after recrystallization.

  The Applicant has now developed a method that allows to eliminate some or all of the aforementioned drawbacks.

  The present invention relates to a process for preparing a compound having the following formula:

NOT

  NH 2 (1) wherein R denotes H or an alkyl group containing from 1 to 10 carbon atoms and which may be substituted with one or more aryl, heteroaryl, hydroxy or alkenyl groups. The two Rs can be the same or different.

  The method, according to the present invention, comprises a step of treatment with active carbon of a solution of the product (P), resulting from the reaction between hydrazine and a carboxylic acid R COOH (R having the same meaning as hereinafter above). The activated carbon is preferably chemically activated and advantageously has meso and / or macro pores. The treatment temperature depends on the concentration of the product solution (P) to be treated and is preferably between 40 and 82 C, advantageously between 65 and 82 C to increase the productivity of the process. The treatment time is preferably between 0.5 and 5 hours.

  The treatment with active carbon in the process according to the present invention may consist in suspending the active carbon in a solution consisting of the product (P). This treatment can also be carried out by passing a solution of the product (P) on an activated carbon cartridge. The latter has the advantage of avoiding the step of separating the activated carbon.

  The amount of activated carbon involved is preferably between 1 and 10% by weight relative to the product (P) to be treated.

  The product (P) may be subjected to a recrystallization step, before or after the active carbon treatment step.

  According to a first embodiment of the process, hydrazine is reacted with a carboxylic acid R COOH, then the reaction water and optionally the dilution water of hydrazine and, for example, distillation are removed, in particular by distillation. acid. A product (P) is obtained in the molten state which is then scaled. The flaked product (P) is dissolved in a solvent, preferably isopropanol, to be treated with activated carbon.

  According to a second embodiment of the process, hydrazine is reacted with a carboxylic acid R COOH, then the reaction water and optionally the dilution water of the hydrazine are removed, in particular by distillation, by distillation. acid. A product (P) is obtained in the molten state which is then scaled. The product (P) chipped is recrystallized and then dissolved in a solvent, preferably isopropanol, to be treated with activated carbon.

  Whatever the embodiment, the process comprises a final recrystallization step followed by drying and drying of the compound of formula (1).

  According to an advantageous form of the process, the recrystallization consists in washing and / or crystallizing in a solvent the product. Preferably, this solvent is isopropanol.

  The hydrazine may be anhydrous or in the form of hydrate N 2 H 4, H 2 O optionally in aqueous solution. It is sufficient to use the hydrate N2H4, H20 in aqueous solution. These solutions may for example contain from 24 to 100% by weight of N 2 H 4, H 2 O.

  R COOH acid can contain up to 20% water. With regard to the formic acid H COOH, a product with more than 90% purity is advantageously used.

  The reaction between the hydrazine and the carboxylic acid is preferably carried out with a carboxylic acid R 2 COOH of between 2 and 5% (molar) and advantageously between 2 and 3% (molar) relative to the stoichiometry.

  This reaction can be carried out at room temperature and atmospheric pressure. In general, the temperature is allowed to rise by the exothermicity of the reaction and then heated to 130-180 ° C. to distill the water, advantageously under an absolute pressure between 20 and mmHg (26 and 133 hr Pa).

  The present invention is particularly suitable for the process for producing the compound of formula (1) wherein R is H, that is 4-amino-1,2,4-triazole.

  The present invention further relates to a compound of formula (1) characterized in that it is in the form of compact crystals, quasi-spherical, average particle size of between 0.4 and 2 mm.

  The purity of the compounds of formula (1) according to the present invention is preferably greater than 99.7% and advantageously greater than 99.9% (by weight).

  The compounds of formula (1), according to the present invention, by their morphology have excellent flowability and can reduce the duration of drying.

  The compounds of formula (1) can be prepared according to the process of the present invention.

  The particularly preferred compound of formula (1) is 4-amino-1,2,4 triazole.

  Experimental part The 4-amino-1,2,4 triazole used in the examples was prepared by reaction between hydrazine hydrate and formic acid and then recrystallized from isopropanol. The crystals are then dried at 60 ° C. under vacuum and then stored at room temperature. This leads to their fattening. The color of the stored sample is gray, the water content present is 800 ppm and the purity is about 99.7% by weight.

Example 1

  1120 g of isopropanol are introduced into a two-liter reactor, and then 595 g of 4-amino-1,2,4-triazole are added. The medium is heated to 70 ° C. and 20 g of activated charcoal (acticarbon CXV) are then introduced. The suspension is then maintained for 1 hour at 70 ° C. The suspension is then filtered through a ClarcellCBR filter aid to separate the activated charcoal. The filtrate is cooled from 70 to 5 ° C. and the temperature is then maintained at 5 ° C. for 30 minutes. The crystals formed are then filtered to separate and washed with 400 g of isopropanol. Finally, the crystals thus washed are dried at 60 ° C. under vacuum.

Example 2

  400 kg of isopropanol are introduced into a 250-liter reactor, and then 120 kg of 4-amino-1,2,4-triazole are added. The medium is heated to 75 ° C., and this temperature is maintained for one hour. After the temperature stage, the recirculation pump is started to perform the active carbon treatment (passage on a CXV acticarbon online filter + media assembly). The chosen treatment time is 4 hours. The solution is cooled to 75 ° C. at 3 ° C. and the temperature is then maintained at 5 ° C. for 30 minutes. The crystals formed are then filtered to separate and washed with 80 kg of isopropanol. Finally, the crystals thus washed are dried at 60 ° C. under vacuum.

  The color of the crystals obtained after treatment in the examples is white, the water content is 80 ppm. The purity of the product is greater than 99.9% by weight. The crystals are in the form of spheres of average diameter of about 1 mm for Example 1 and about 2 mm for Example 2. Their drying is fast.

  The crystallization could be carried out rapidly and no deposits on the walls of the reactor were observed.

Example 3

  The procedure is identical to that of Example 1 except that it operates in the absence of activated carbon.

  The color of the crystals obtained after treatment remains gray. The crystals are in the form of fine needles 0.2 mm long and 0.01 mm wide and drying is long and difficult.

  Crystallization proceeded slowly because large quantities of crystals were deposited on the walls of the reactor which limits the speed of the recrystallization step and strongly penalizes the productivity of the process (loss of product).

Claims (6)

  A process for preparing compounds of formula (1): NH 2 (1) wherein R denotes H or an alkyl group containing from 1 to 10 carbon atoms and which may be substituted with one or more aryl, heteroaryl, hydroxy or alkenyls comprising a step of treating with active carbon a solution of the product (P), resulting from the reaction between hydrazine and a carboxylic acid R COOH (R having the same meaning as above).   2. Method according to claim 1 characterized in that the coal is chemically activated, preferably having meso and / or macro pores.   3. Method according to claim 1 or 2 characterized in that the treatment temperature is between 40 and 82 C, preferably between 65 and 82 C. 4. Method according to any one of the preceding claims, characterized in that it comprises a recrystallization step before or after the active carbon treatment. 20 5. Compounds of formula (1): NH 2 (1) in which R denotes H or an alkyl group containing from 1 to 10 carbon atoms and which may be substituted with one or more aryl, heteroaryl, hydroxy or alkenyl groups, characterized in that they are in the form of compact crystals, almost spherical, average particle size between 0.4 and 2 mm.   6. A process or compound according to any one of the preceding claims wherein R is H.