Diethyl Ether → 2,6-Dichlorobenzothiazole

Participants

Reaction Steps

2-Amino-6-chlorobenzothiazole (15.7 g, 85 mmol) in H3PO4 (85%) (470 ml) was heated to 100 degrees and dissolved. Then clear solution was cooled and vigorously stirred by mechanical stirrer. NaNO2 (17.6 g, 255 mmol) in water (30 ml) was added slowly keeps the temperature below 0 degrees. Separately a solution of CuSO4/5H2O (85 g), NaCl (107 g) in water (350 ml) was cooled to −5 degrees and stirred by mechanical stirrer. After Potassium Iodide Starch paper's color was disappeared Diazonium solution was keeping cold and added slowly to the copper chloride solution with vigorous stirring. The reaction Mixture was allowed to warm to room temperature. After 1-hour water (1 L) and ether (1 L) were added to the reaction mixture and extracted twice. Organic layer was washed by water and dried over anhydrous MgSO4 and concentrated. Crude residue was purified by silica gel chromatography (H/A=4/1, 180 g of silica gel) to provide title compound 363 (7.46 g, 48%).

Provenance & Evidence