4,5,6,7-TETRABROMOBENZOTRIAZOLE

95-14-7

17374-26-4

The method reported in literature [39] was used with appropriate modifications. 1H-benzotriazole (32, 3 g) was dissolved in a mixture of 69% HNO3 (50 mL) and 100% HNO3 (3 mL). Subsequently, the solution was heated to 80 °C and Br2 (6 eq.) was added slowly and dropwise over a period of 1 hour. The reaction mixture was stirred vigorously at 60 °C for 48 h and then cooled to room temperature. Unreacted Br2 was trapped and removed by 20% aqueous Na2S2O5 solution (100 mL) under nitrogen protection.Next, the reaction mixture was poured into a mixture of ice-cold H2O (200 mL) and saturated aqueous Na2S2O5 solution (10 mL). The resulting orange precipitate was collected by filtration and washed sequentially with H2O (50 mL) and EtOH (50 mL). The crude product was purified by multiple washes with hot MeOH (50 mL) to afford a white solid 4,5,6,7-tetrabromo-1H-benzotriazole (TBBt, 34, 7.45 g, 17.14 mmol, 68% yield). The structure of the product was confirmed by high-resolution mass spectrometry (HRMS).1H NMR, 13C NMR and melting point data were in agreement with those reported in the literature.Properties of TBBt 34 are as follows: white solid; melting point 264-266 °C (MeOH) [literature value: 262-266 °C (acetic acid)][89]; HRMS (ESI-TOF) m/z: [M + H]+ C9H7Br5N3+ m/z calculated value: 435.6941, measured value: 435.6629.