2-Mercapto-4-hydroxy-5-cyanopyrimidine

B. 2-Mercapto-4-hydroxy-5-cyanopyrimidine. The aqueous filtrate from which the crude 2-mercapto-4-amino-5-carbethoxy-pyrimidine separated is cooled overnight at 0°, and the cyano-pyrimidine that precipitates is collected on a suction filter. The crude product is recrystallized from about 200 ml. of 10% acetic acid with 1 g. of decolorizing charcoal added. Two additional recrystallizations done similarly give the pure cyanopyrimidine as faintly yellow crystals, m.p. 265-272° (dec.) (Note 3). The yield is 10-18 g. (7-12%). 

AND 2-MERCAPTO-4-HYDRO XY-5-CYANOPYRIMIDINE (5-Pyrimidinecarbonitrile, 4-hydroxy-2-mercapto-,)... 

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