[CH3:1][S:2]([O:5][C:6]1[CH:11]=[C:10]([NH2:12])[C:9]([F:13])=[CH:8][C:7]=1[Cl:14])(=[O:4])=[O:3].Cl.[N:16]([O-])=O.[Na+].[OH-].[Na+]>O>[CH3:1][S:2]([O:5][C:6]1[CH:11]=[C:10]([NH:12][NH2:16])[C:9]([F:13])=[CH:8][C:7]=1[Cl:14])(=[O:3])=[O:4]
A mixture of 2-chloro-4-fluoro-5-aminophenyl methanesulfonate (24.0 g), 35% hydrochloric acid (63 g) and water (48 ml) was stirred at 60° C. for 30 minutes. Then, a solution of sodium nitrite (9.1 g) in water (55 ml) was added dropwise to the resulting mixture at -20° C. to effect diazotization reaction. The resulting mixture was added under stirring to a preformed and cooled (-20° C.) solution of 35% hydrochloric acid (52 ml) and stannous chloride hydrate (58 g) in water (100 ml) and the stirring was continued for 30 minutes under cooling. Then, the reaction solution was brought to room temperature and the pH of the solution was adjusted to 8.0 with an aqueous sodium hydroxide solution. Then, the reaction solution was extracted with toluene and tetrahydrofuran and the extract was washed with water, dried over anhydrous sodium sulfate and subjected to distillation under a reduced pressure to remove the solvent used, affording the titled compound (21.9 g) of the formula: ##STR54## as yellow crystals. Recrystallization from cyclohexane gave pale yellow crystals having melting point 75°-77° C.
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