3-Iodo-6-nitroindazole

7597-18-4

70315-70-7

General procedure for the synthesis of 3-iodo-6-nitroindazole from 6-nitro-1H-indazole: 6-nitroindazole (45.08 kg) was dissolved in N,N-dimethylformamide (DMF, 228 kg), and powdered potassium carbonate (77 kg) was added while controlling the temperature of the reaction system ≤30°C. The reaction was carried out by slow dropwise addition of iodine (123 kg) solution in DMF (100 kg) over 5 to 6 hours. A solution of iodine (123 kg) dissolved in DMF (100 kg) was added slowly and dropwise over a period of 5 to 6 hours, during which the reaction temperature was maintained at ≤35°C (note: the reaction is exothermic). The reaction mixture was stirred continuously at 22°C for 1 to 5 hours until high performance liquid chromatography (HPLC) monitoring showed that the reaction was complete. Subsequently, the reaction mixture was slowly added to an aqueous solution (455 kg) containing sodium thiosulfate (68 kg) and potassium carbonate (0.46 kg) and the temperature was controlled to be ≤30°C during addition. The mixture was continued to be stirred at 22°C for 1.5 hours. Water (683 kg) was added to precipitate the product and the slurry was stirred at 22°C for 1 to 2 hours. The solid product was collected by filtration, washed with water (2 x 46 kg) and subsequently dried in a vacuum oven at 50 °C and 25 mmHg for 24 to 48 hours to give a yellowish-white solid 3-iodo-6-nitroindazole (74.7 kg, HPLC purity 86.6%, moisture content 0.2%).