CS253429B1 - Process for preparing 2-isopropylamino-4-ethylamino-6-chlor-s-triazine - Google Patents

Abstract

Production of 2-isopropylamino-4-ethylamino-6-chloro-s-triazine is solved condensation of cyanuric chloride with ethylamine, isopropylamine and sodium hydroxide. Condensation is carried out in an aqueous medium with addition of alkali metal chloride, most commonly sodium chloride. After completion of The reaction was filtered to remove trazine from the reaction mixture and processed by conventional means. 2-isopropylamino-4-ethylamino-6-chloro- -triazine is used as a herbicide in agriculture.

Description

The present invention provides the preparation of 2-isopropylamino-4-ethylamino-6-chloro-s-triazine by reacting cyanuric chloride with ethylamine, isopropylamine and sodium hydroxide in an aqueous medium with the addition of an alkali metal chloride.

Among the best known and most widely produced s-triazine herbicides are 2-isopropylamino-4-ethylamino-6-chloro-s-triazine (atrazine). Herbicidal effects were discovered in Switzerland in 1954 and are described in Swiss Patent 229 227. The preparation of atrazine by reaction of cyanuric chloride, ethylamines, isopropylamine and sodium hydroxide in aqueous chlorobenzene is described in Czechoslovak patent 110,352. in anhydrous organic solvent, wherein anhydrous ammonia is used to bind the resulting hydrogen chloride. Swiss Patent 508,640 is disclosed. The product obtained contains 92% atrazine. The effect of pH on atrazine yield is described in the patents NDR and NSR. According to the GDR Pat. 51,646, the best yield d-is obtained if, in the first reaction step, i.e.. j. by adding the first amine and the alkali metal hydroxide, a pH of 6 to 8 is maintained in the second reaction stage, i.e. the reaction is carried out at a pH of 6 to 8; j. after addition of the second amine and alkali metal hydroxide, the pH is maintained at 8.5-9. The atrazine yield is 96%. In the German patent no

032 861 gives a pH of 6.5-10 in the first stage. U.S. Pat. No. 3 328 399 and no

No. 586,679 describes a process for preparing atrazine from cyanuric chloride, ethylamines, isopropylamine in anhydrous medium at a temperature of 120-170 ° C while distilling off the resulting hydrogen chloride. The advantage of the method is that the problem of waste waters containing mineral salts is eliminated. In Swiss patent no. No. 546,247 describes an adiobotic process for producing atrazine in a water-insoluble solvent by reacting ethylamines, isopropylamine, alkali hydroxide with cyanuric chloride. In French Patent 2,296,628, Romanian Patent 68,016, Japanese Patent no. 131 592 (1977), it is recommended that the first isopropylamine be metered in at amine dosing for atrazine production. Banks C. and spo-1 J. Am. Chem. Soc. BB, 1771 (1944) and Friedheim E., J. Am. Chem. Soc. 6B 1725 (1944) recommends a temperature of about 0 ° C in the first reaction stage of atrazine production and a second reaction stage at temperatures of 30 to 50 ° C. In the first reaction step, a mixture of water and ice is used as the reaction medium, optionally water, ice and an organic solvent.

A disadvantage of the above processes is that the condensation takes place in the presence of an organic solvent which must be separated from the product after the condensation has been completed.

The above-mentioned drawbacks are alleviated by the process for the preparation of 2-isopropylamino-4-ethylamino-6-chloro-s-triazine, which consists in reacting cyanuric chloride with aqueous solutions of ethylamines, isopropylamine and sodium hydroxide. The reaction takes place in an aqueous medium with the addition of an alkali metal chloride, most often sodium chloride.

It is an advantage of the invention that water with the addition of alkaline chloride is used as the reaction medium. After completion of the reaction, atrazine is filtered from the reaction mixture and the alkali metal chlorides are washed with water. The process is much simpler than using an organic solvent that needs to be regenerated, which requires a sentence of energy. The addition of the alkali metal chloride to the aqueous medium reduces the freezing point of the aqueous solutions, which is particularly advantageous at reaction temperatures in the region of 0 ° C, while the cooling of the reaction mixture with brine does not form ice on the cooling surfaces. cooling the reaction mixture. Addition of sodium chloride to the aqueous medium reduces the cyanuric chloride losses due to hydrolysis with water. According to the process, atrazine of high purity is obtained which is equal to the product obtained by the reaction in the presence of an organic solvent. Typically, atrazine is obtained having a content of 96 to 99% by weight.

Example 1

225 ml of water was added to the reaction flask in which 23 g of sodium chloride was dissolved. Then 30 g of cyanuric chloride was added to the solution. The contents of the flask were cooled to 10 ° C. 48 ml of 21 wt. aqueous isopropylamine solution. The mixture was then allowed to react for 30 minutes at 15 ° C. Subsequently, 5-0 ml of 10.6 wt. aqueous sodium hydroxide solution and the mixture was allowed to react at 15 ° C for 1 hour. The pH of the suspension after reaction was 7.4. Thereafter, 21.4 ml of 39 wt. ethylamine and the reaction mixture was allowed to stir at 20 ° C. 50 ml of 10.6% by weight were then added thereto. aqueous sodium hydroxide solution and the mixture was allowed to react for 1 hour at 20 ° C. The obtained atrazine was filtered from the suspension, washed with water and dried. 31.6 g of technical atrazine were obtained

97.6 wt. atrazine, 1.6 wt. % simazine and 0.7 wt. propazine.

Example 2

The procedure of Example 1 was followed except that 25 g of potassium chloride was used instead of sodium chloride. The temperature in the first reaction step instead of 15 ^Q C was only 5 ° C and the second step instead of 20 ° C was only 10 ° C. 31.5 g of technical atrazine was obtained, which contained 97.4% by weight of the composition. atrazine, 0.9 wt. simazine and 1.6 wt. propazine.

The invention can be used in the production of technical atrazine, which is used as a herbicide in agriculture,

Claims (1)

SUBJECT Process for preparing 2-isopropylamino-4-ethylamino-6-chloro-s-triazine by condensation of cyanuric chloride with aqueous solutions of ethylamine, isopropylamine and sodium hydroxide in an aqueous medium, characterized in that the condensation is carried out in aqueous medium with the addition of an alkali metal chloride.