2-Bromo-3,5-dichloropyridine

Uses

2-Bromo-3,5-dichloropyridine is used in various fields, including pharmaceuticals, agrochemicals, and materials science. It is an essential intermediate for the synthesis of different chemical compounds, such as fungicides, herbicides, and insecticides.

Synthesis

Step 1: Synthesis of 2-bromo-3,5-dichloropyridine To a solution of 3,5-dichloropyridin-2-amine (1.0 g, 6.2 mmol) dissolved in 40% aqueous hydrobromic acid (8 mL), bromine (2.8 g, 17 mmol) was slowly added dropwise at -20 °C. The resulting orange-colored suspension was stirred continuously for 2 hours at -20 °C. Subsequently, aqueous sodium nitrite (1.1 g, 17 mmol) was added at the same temperature. The reaction mixture was warmed up to ambient temperature and stirring was continued for 2 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and the pH was adjusted with 30% aqueous sodium hydroxide solution to about 12. The reaction mixture was extracted with ether to give a light yellow organic phase. The organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give the title compound 2-bromo-3,5-dichloropyridine as a yellow solid (730 mg, 52% yield). 1H NMR (400MHz, CDCl3) δ 8.27 (d, J=2.3Hz, 1H).

References

[1] Patent: US4510148, 1985, A
[2] Patent: WO2008/70908, 2008, A1. Location in patent: Page/Page column 71-72
[3] Patent: WO2015/187845, 2015, A1. Location in patent: Paragraph 0239
[4] European Journal of Medicinal Chemistry, 1989, vol. 24, # 3, p. 249 - 258
[5] Phosphorus and Sulfur and the Related Elements, 1987, vol. 34, p. 123 - 132