O.NN.[N:4]1[C:13]2[C:8](=[CH:9][CH:10]=[CH:11][CH:12]=2)[N+:7]([O-])=[CH:6][C:5]=1[OH:15].[OH-].[Na+]>[Ni]>[N:4]1[C:13]2[C:8](=[CH:9][CH:10]=[CH:11][CH:12]=2)[N:7]=[CH:6][C:5]=1[OH:15]An aqueous Raney nickel paste (containing 0.5 g of metallic nickel) and 5.0 g of a 80% aqueous hydrazine hydrate solution were added dropwise to 200 g of an aqueous solution containing 16.2 g of 2-quinoxalinol-4-oxide and 8 g of sodium hydroxide at a temperature of 40° to 50° C., and the resulting mixture was stirred at 40° to 70° C. for 5 hr, whereby the reducing reaction was terminated. The catalyst was then recovered by filtration, and 35% hydrochloric acid was added dropwise to the filtrate at 50° to 60° C. to adjust the pH to 4. The precipitated crystal was collected by filtration, washed with water and dried to give 13.4 g (yield 92%) of 2-quinoxalinol with melting point of 268° C.
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