General procedure for the synthesis of 4-fluoro-5-nitrobenzene-1,2-diamine from N,N'-(4-fluoro-5-nitro-1,2-phenylene)bis(4-methylbenzenesulfonamide): 158 mg (0.33 mmol) N-[4-fluoro-5-nitro-2-(4-toluenesulfonylamino)-phenyl]-4-methylbenzenesulfonamide was suspended in a mixture of 35 μL deionized water and 360 μL of concentrated sulfuric acid in a mixed solution, and the suspension was heated at 80 °C for 1 hour. Upon completion of the reaction, the reaction mixture was poured into 10 mL of deionized water and a yellow solid was precipitated. The aqueous suspension was heated to boiling to completely dissolve the solid and subsequently cooled to room temperature. The pH of the solution was adjusted to about 9 with concentrated ammonia, at which point an orange solid precipitated. The solid product was separated by filtration, washed with deionized water and dried in air. A final product of 49 mg was obtained in 88% yield.
