Synthesis
To a 50 mL single-necked round-bottomed flask, 20 mL of concentrated sulfuric acid was added at room temperature, followed by the slow addition of 6 mL of bromobenzene and continuous stirring at room temperature. The reaction mixture was stirred for 30 minutes to form a white turbid liquid. Next, 1.0 g of thiosalicylic acid was added in batches over 30 minutes and the reaction continued to be stirred at room temperature for 20 to 24 hours. Subsequently, the reaction system was warmed to 100 °C and maintained for 2 to 3 hours. Upon completion of the reaction, it was cooled to room temperature and the reaction solution was carefully poured into ice water. The precipitated solid product was collected by diafiltration. The resulting solid was suspended in 20% aqueous sodium hydroxide solution, stirred for 2 hours and then diafiltered again. Finally, the filter cake was washed with water to neutrality to give the yellow solid product 2-bromo-9H-thioxanthen-9-one in 80.3% yield.
References
[1] Patent: CN107129487, 2017, A. Location in patent: Paragraph 0031; 0032; 0030
[2] Patent: CN108358905, 2018, A. Location in patent: Paragraph 0189-0190
[3] Patent: CN108586441, 2018, A. Location in patent: Paragraph 0134-0136
[4] Patent: CN108727405, 2018, A. Location in patent: Paragraph 0113; 0114; 0115; 0116
[5] Patent: CN108218831, 2018, A. Location in patent: Paragraph 0057-0059
