Verfahren zur Herstellung von 4,5,6-Trichlor- und 2,4,5,6-Tetrachlorpyrimidin

The invention concerns a method of preparing 4,5,6-trichloro- and 2,4,5,6-tetrachloropyrimidine by reacting 3-dimethylaminopropionitrile with HC1 and Cl2, the method comprising a) a first step in which 3-dimethylaminopropionitrile is reacted with Cl2 in a solvent at a temperature of -10 to 55 DEG C and b) a second step in which the reaction mixture obtained in the first step is reacted, at a temperature of over 55 DEG C, with Cl2, optionally in the presence of a catalyst. The method is characterized in that the second step takes place with the product of the reaction in the first step in microcrystalline form with a mean crystal size of