S(=O)(=O)(O)O.[OH:6][C:7]1[C:8]([C:13]([NH2:15])=[O:14])=[N:9][CH:10]=[CH:11][N:12]=1.[N+:16]([O-])([O-:18])=[O:17].[K+].[OH-].[Na+]>O>[OH:6][C:7]1[C:8]([C:13]([NH2:15])=[O:14])=[N:9][C:10]([N+:16]([O-:18])=[O:17])=[CH:11][N:12]=1Into 1.2 L of 97% sulfuric acid was added and dissolved 208.0 g of 3-hydroxy-2-pyrazinecarboxamide, while keeping the solution at 10-25° C. by cooling it with ice. To the solution thus obtained was added 185.0 g of potassium nitrate at 30-35° C., and the mixture thus obtained was stirred at room temperature for 15 hours and then at 40° C. for 2 hours. After cooling the reaction mixture to 20° C., it was poured into 6 L of ice water and stirred at room temperature for one hour, and the deposited matter was collected by filtration and washed with two 500 mL portions of water. The solid product thus obtained was suspended in 1 L of water, pH was adjusted to 1.5 with 5 mol/L aqueous solution of sodium hydroxide, and then the solid matter was collected by filtration. The solid was washed successively with 500 mL of water and 500 mL of acetone to obtain 180.0 g of 3-hydroxy-6-nitro-2-pyrazinecarboxamide as a solid product.
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