CS258211B1 - A method for preparing 2-isopropylamino-4-atylamino-6-chloro-s-triazine - Google Patents

Abstract

It deals with the preparation of aqueous solutions of ethylamine, isopropylamine and sodium hydroxide, which are used in the production of atrazine by condensing the above-mentioned solutions with cyanide chloride. After filtering off the atrazine after the reaction, the obtained filtrate is used to prepare the aqueous solutions of ethylamine, isopropylamine and sodium hydroxide used in the following condensation. Atrazine is used as an agricultural herbicide.

Description

258211 2

The present invention provides a 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.

The most well-known and widely produced s-triazine herbicides include 2-propylamino-4-ethylamino-6-chloro-s-triazine (atrazine). Herbicidal effects have been discovered in 1954 in Switzerland and described in Swiss Patent 229,227. The organic solvent, wherein anhydrous ammonia is used to bind the resulting hydrogen chloride, is described in U.S. Pat. No. 508,640. The product obtained contains 92% of atrazine. The influence of pH on the atrazine yield is described in the patents of GDR and NSR. According to the German Patent No. 51,646, the best yield is obtained when, in the first reaction stage, i.e. after the addition of the first amine and the alkali metal hydroxide, a pH of 6-8 is maintained in the second reaction stage, i.e. after the addition of the stiff amine and the alkali metal hydroxide. the pH of the atrazine is 96%. In German Patent No. 2,032,861, the pH in the first stage is 6.5 to 10. In U.S. Pat. No. 3,328,399 and 3,586,679 disclose a process for the preparation of atrazine from cyanuric chloride, ethylamine, isopropylamine in an anhydrous medium at 120-170 DEG C. with distilled hydrogen chloride. The advantage of the method is that the problem of waste water with the contents of mineral salts is eliminated. Swiss Patent No. 546,247 describes an adiabatic process for the production of arazrazine in a water-insoluble solvent by reaction of ethylamine, isopropylamine, an alkali metal hydroxide with cyanuric chloride.

Vo franc. pat. 2 296 628, rum. pat. 60 016, jap. pat. 131, 592 (1977), it is recommended that the first isopropylamine be dosed for the amine dosage in the manufacture of atrazine. Banks C and Spol. J. Am. Chem. Soc. 66, 1771 (1944) and Friedheim, E., J. Am. Chem. Soc. 66, 1725 (1944) recommend at a first reaction stage for the production of atrazine a temperature of about 0 ° C and a second reaction step at temperatures of 30 ° C to 50 ° C. In the first reaction step, water and ice are used as reaction medium, water, ice and organic solvent are used.

Ethylamine, isopropylamine and sodium hydroxide are applied in the form of aqueous solutions prepared from their concentrated solutions by dilution with water, whereby the solubility of the water lasting in the form of a precipitated, filterable precipitate is precipitated. The precipitated salts are most often separated by sedimentation and sludge depletion, with loss of reaction components. After completion of the reaction, the atrazine is filtered from the mother liquor containing sodium chloride. The sodium chloride mother liquor contains calcium and magnesium salts which precipitate upon addition of sodium hydroxide or amines.

The aforementioned drawbacks are alleviated by the preparation of amine and hydroxide solutions in the production of 2-isopropyl-4-ethylamino-6-chloro-s-triazine, by the attachment of atrazine by condensation of cyanuric chloride, isopropylamine, ethylamine and sodium hydroxide. which is filtered from the reaction mixture. The sodium chloride mother liquor after filtration contains dissolved sodium chloride and unreacted amines. Sodium chloride solution is used to dilute amines and sodium hydroxide. Sodium chloride must not crystallize in dilute amine and sodium hydroxide solutions and its concentration must be lower than the sodium chloride concentration in the saturated solution.

According to the present invention, better utilization of ethylamine, isopropylamine, and sodium hydroxide raw materials is achieved, as salt precipitation during their dilution and thus soil contamination is avoided. At the same time, the amount of waste water is also reduced.

Claims (1)

Example 1 3 500 ml of water cooled to 5 ° C was added to the flask, then 500 g of cyanuric chloride was added and 860 ml of 20.3% wt. of an isopropylamine aqueous solution and 1800 ml of 10.2 wt. aqueous sodium hydroxide solution. The reaction mixture was allowed to stir for 40 minutes. Then, 360 ml of 40.1% wt. aqueous ethylamine solution and 1800 ml 10.2% wt. aqueous sodium hydroxide solution. The reaction mixture was allowed to react for 60 minutes. The atrazine obtained was filtered off. sodium chloride, 70 mg / l isopropylamine, 40 mg / l ethylamine. The filtrate was 7,500 ml and discarded. The filter cake was washed with 2500 mL of water. The atrazine was dried at 105 ° C. 560 g of product were obtained, which contained 94.2 wt. % of atrazine, 3.1 wt. 2,4-bis-ethylamino-6-chloro-s-triazine (simazine) and 2.4% wt. 2,4-bis-isopropyl-amino-6-chloro-s-triazine (propazine). EXAMPLE 2 The procedure of Example 1 was followed except that the isopropylamine solution was prepared by diluting 200 g with 81.2% wt. of isopropylamine with 580 ml of the filtrate of Example 1, the NaOH solution was prepared by diluting 700 ml of 42% wt. NaOH aqueous solution with 2,900 ml of the filtrate of Example 1. The monoethylamine solution was prepared by dissolving 125 g of 98.5% wt. of monoethylamine in 175 ml of the filtrate of Example 1. 572 g of product were obtained with a content of 96.1% by weight. atrazine. The filtrate contained 5.8% wt. sodium chloride. After repeating the experiment of Example 2 ten times, the sodium chloride content of the filtrate was 7.9% by weight. The invention can be used in the production of atrazine, which is used as a herbicide in agriculture. OBJECT OF THE INVENTION Process for the preparation of 2-isopropylamino-4-ethylamino-6-chloro-s-triazine by reaction of cyanuric chloride with aqueous solutions of ethylamine, isopropylamine and sodium hydroxide in an aqueous solution of sodium chloride, whereby 2-isopropylamino-4-ethylamino-6- the chloro-s-triazine is filtered from the mother liquor containing sodium chloride, characterized in that the mother aqueous sodium chloride solution is used to prepare aqueous solutions of ethylamine, isopropylamine and sodium hydroxide for further condensation.