2-Chloro-6-(trifluoromethoxy)-benzothiazole

133840-98-9

133840-96-7

Compound 2 (12.45 g, 0.05 mol) was added slowly in batches to preheated thionyl chloride (SOCl2, 120 mL) at 65 °C. The reaction mixture was stirred at 60 °C for 5 hours. Upon completion of the reaction, excess acetyl chloride was removed by distillation under reduced pressure, and the residue was dissolved in dichloromethane (CH2Cl2) and distilled again under reduced pressure to remove the solvent. This operation was repeated at least three times to ensure complete removal of thionyl chloride. The final residue was dissolved in dichloromethane, washed three times with water and dried over anhydrous sodium sulfate (Na2SO4). The solvent was removed by concentration under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography using petroleum ether (60-90 °C) as eluent to give compound 3 (10.71 g, 85% yield) as a white solid. The product characterization data were as follows: melting point 38-39 °C; IR (KBr) υmax 3099, 3078, 2361, 1480, 1452, 1262, 1164, 1016, 865 cm-1; 1H NMR (CDCl3, 500 MHz) δ 7.96 (1H, d, J = 8.9 Hz, Ar-H), 7.66 (1H, s , Ar-H), 7.37 (1H, d, J = 8.9 Hz, Ar-H); ESI-MS: m/z 251.91 [M-H]-; Calculated elemental analysis (C8H3ClF3NOS): C, 37.88; H, 1.19; N, 5.52; Measured values: C, 37.95; H, 1.13; N, 5.59.