[NH2:1][C:2]1[C:9]([F:10])=[CH:8][C:5]([C:6]#N)=[C:4]([F:11])[CH:3]=1.S(=O)(=O)(O)O.[OH2:17].[OH-:18].[Na+]>O1CCOCC1>[NH2:1][C:2]1[C:9]([F:10])=[CH:8][C:5]([C:6]([OH:18])=[O:17])=[C:4]([F:11])[CH:3]=1To a solution of 4-amino-2,5-difluorobenzonitrile (6.21 g, 38.28 mmol) in dioxane (32.5 mL) was added 52.2 mL of sulphuric acid 73% p/p. The reaction mixture was stirred at 80° C. for 96 hours. The crude was poured into 250 mL of water and basified by sodium hydroxide 32% until basic pH and washed with methylen chloride. The aqueous phase was neutralized with hydrochloric acid 5N and the crude was extracted with ethyl acetate, washed with brine, dried and the solvent was removed under reduced pressure to give the title compound as a white solid (42%), which was used in the next step without further purification.
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