Synthesis
The general procedure for the synthesis of 5-bromo-1H-benzotriazole from 4-bromo-o-phenylenediamine was as follows: 4-bromobenzene-1,2-diamine (10 g, 53.5 mmol) was dissolved in a mixture of acetic acid (20 ml, 349 mmol) and water (100 ml) in an ice-bath at 0-5 °C. A solution of sodium nitrite (4.06 g, 58.8 mmol) in water (10 ml) was added slowly and dropwise. The ice bath condition was maintained and the reaction mixture was stirred for 1 hour. Subsequently, additional acetic acid (20 ml, 349 mmol) was added and the reaction system was heated to 80-85°C and stirring was continued for 1 hour. Upon completion of the reaction, the hot solution was filtered to remove insoluble black impurities. The filtrate was cooled to 0-5 °C and left to age for 30 min. The precipitate precipitated was washed with water and dried under vacuum at 45 °C to afford the target product 5-bromo-1H-benzotriazole in a yield of 9.48 g (90% yield).
References
[1] Organic and Biomolecular Chemistry, 2018, vol. 16, # 37, p. 6902 - 6907
[2] Patent: US2012/65191, 2012, A1. Location in patent: Page/Page column 26; 27
[3] Bioorganic and Medicinal Chemistry Letters, 2002, vol. 12, # 5, p. 827 - 832
[4] Bioorganic and Medicinal Chemistry, 2006, vol. 14, # 20, p. 6832 - 6846
[5] Patent: KR2016/30566, 2016, A. Location in patent: Paragraph 0267-0270
