Synthesis
Step 1: Bromination reaction
3-Hydroxybenzonitrile (3.2 g, 26.8 mmol) was dissolved in glacial acetic acid (20 ml) and acetic acid solution (5 ml) of bromine (4.2 g, 23.3 mmol) was added slowly dropwise for a controlled period of 5 minutes. The reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the mixture was filtered. The filtrate was poured into water (100 ml) containing a small amount of sodium thiosulfate to quench the unreacted bromine. The insoluble material was collected and the filter cake was mixed with warm methanol (15 ml) and filtered through diatomaceous earth. The filtrate was slowly diluted with water to precipitate, the precipitate was collected and dried to give 2-bromo-5-hydroxybenzonitrile in 22% yield (1.0 g) with a melting point of 183-185 °C.
References
[1] ACS Medicinal Chemistry Letters, 2018, vol. 9, # 2, p. 120 - 124
[2] Patent: WO2011/34828, 2011, A1. Location in patent: Page/Page column 80
[3] Patent: WO2004/35556, 2004, A1. Location in patent: Page 95
