Guanidine Hydrochloride → 3-Amino-1,2,4-benzotriazine

To a stirring mixture of guanidine hydrochloride (160 mg, 1.7 mmol) and t-BuOK (670 mg, 6 mmol) in DMSO (4 mL) was added one portion of nitrobenzene (123 mg, 1 mmol) at room temperature. The mixture turned red in one minute. In 20 to 30 minutes the mixture was quenched with a saturated, aqueous solution of ammonium chloride. A yellow precipitate was formed and removed by filtration. The precipitate was then washed with water, dried in the air, and recrystallized from benzene or ethanol to give 105 mg (72%) of 3-amino-1,2,4-benzotriazine. The melting point was determined to be 203–205° C., consistent with the melting point (207° C.) of 3-amino-1,2,4-benzotriazine synthesized by other known methods (J. Chem. Soc. (B) (1970) 911).