S(=O)(=O)(O)O.[F:6][C:7]1[N:12]=[C:11]([C:13]#[N:14])[C:10]([OH:15])=[N:9][CH:8]=1.[OH-:16].[Na+]>O>[F:6][C:7]1[N:12]=[C:11]([C:13]([NH2:14])=[O:16])[C:10]([OH:15])=[N:9][CH:8]=114.39 g of concentrated sulfuric acid was added to 3.45 g of the oily 6-fluoro-3-hydroxypyrazine-2-carbonitrile, and the resulting mixture was stirred at 50° C. for 4 hours. The reaction mixture was then added dropwise over a period of 20 minutes to 44.5 ml of water that had been cooled to 3° C. Following completion of the dropwise addition, the resulting mixture was stirred for 20 minutes at a temperature of not more than 10° C. Subsequently, 10.17 g of a 28% aqueous solution of sodium hydroxide was added dropwise to the reaction mixture over a period of 15 minutes. Following completion of the dropwise addition, the mixture was stirred at the same temperature for 30 minutes. The solid product was then filtered off, and washed with 18 ml of water, yielding 2.22 g (yield: 92.3%) of 6-fluoro-3-hydroxypyrazine-2-carboxamide.
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