Bayer Aktiengesellschaft

Volker Kass

Guido Steffan

Gunther Cramm

Jurgen-Dietrich Meier

Horst Siffrin

Christian Munster

Process for the preparation of 2,4,6-trichloropyrimidine, characterized in that barbituric acid is reacted in a first reaction step with phosphorus oxychloride in the presence or absence of a catalyst, and then, in a second reaction step, is reacted with phosphorus pentachloride or with reactants forming this, in particular phosphorus trichloride and chlorine, at a temperature of 20 to below 80.degree. C.

Process for the preparation of 2,4,6-trichloropyrimidine

4,6-Dichloropyrimidines are obtained by the reaction of 4,6-dihydroxypyrimidines with excess phosphoryl chloride in a particularly advantageous manner when no base is added, during and/or after the reaction 0.75 to 1.5 mol of phosphorus trichloride and 0.7 to 1.3 mol of chlorine are added per equivalent of exchanged hydroxyl groups so that an excess of phosphorus trichloride with respect to chlorine is always present, and finally phosphorus trichloride and phosphoryl chloride are separated off. This process can be carried out in a particularly simple manner and also continuously.

Process for the preparation of 4,6-dichloropyrimidines

2-aryl-ethane-sulphonic acids of the formula

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Leverkusen, Germany

Volker Kass