5-Amino-1-phenyl-4-pyrazolecarboxamide → 7-phenyl-3H,4H,7H-pyrazolo[3,4-d][1,2,3]triazin-4-one

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Reaction Steps

1 g of 5-amino-1-phenyl-4-pyrazolecarboxamide in 18 ml of glacial acetic acid and 10 ml of concentrated hydrochloric acid was stirred at 0° C. during the addition of a solution of 0.4 g of sodium nitrite in 6 ml of water. The mixture was held at 0° C. for 20 minutes, then allowed to warm to room temperature and stirred for a further 2 hours. The precipitated product was filtered off and recrystallized from ethanol to yield 580 mg of 7-phenyl-7H-pyrazolo[3,4-d]-1,2,3-triazin-4(3H)-one of melting point 150°-151° C.

Provenance & Evidence