S(=O)(=O)(O)O.[F:6][C:7]1[CH:8]=[C:9]2[C:14](=[CH:15][CH:16]=1)[N:13]=[C:12]([CH3:17])[CH:11]=[CH:10]2.[N:18]([O-:20])=[O:19].[Na+].[N+]([O-])(O)=O.[OH-].[NH4+]>>[F:6][C:7]1[C:8]([N+:18]([O-:20])=[O:19])=[C:9]2[C:14](=[CH:15][CH:16]=1)[N:13]=[C:12]([CH3:17])[CH:11]=[CH:10]2To 3.5 l of fuming sulfuric acid were added, with cooling, 600 g (3.73 moles) of 6-fluoroquinaldine in small portions (5 to 10 g). To this mixture was added about 0.1 g of sodium nitrite, followed by the dropwise addition of 261 ml of fuming red nitric acid over a period of six hours. The temperature of the mixture was maintained at 5° to 10° C. during the addition. The mixture was stirred at 20° C. for sixteen hours, then poured into 3 gallons of ice. Ammonium hydroxide was added, with cooling, to basify the mixture. The precipitated solid was separated by filtration, and dissolved in about two liters of warm toluene. The solution was dried over magnesium sulfate, filtered and evaporated to provide a yellow solid (6-fluoro-5-nitroquinaldine, m.p. 105°-108° C.) which was recrystallized from 1,2dicholoroethane. The structural assignment was confirmed by nuclear magnetic resonance and infrared spectral analyses.
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