25194-01-8

2,6-Dichloro-4-nitropyridine (cas# 25194-01-8) is a compound useful in organic synthesis.

Synthetic Communications, 18, p. 659, 1988 DOI: 10.1080/00397918808077351

The general procedure for the synthesis of 2,6-dichloro-4-nitropyridine from 2,6-dichloropyridine-N-oxide was as follows: 2,6-dichloropyridine-N-oxide (12.8 g, 78 mmol) was added to a mixed solution consisting of 95% concentrated nitric acid (21 mL) and 98% concentrated sulfuric acid (50 mL). The reaction was stirred at 148 °C for 1 h. The temperature was subsequently raised to 156 °C until no more nitrogen dioxide gas was released. After completion of the reaction, the reaction solution was cooled to room temperature and slowly poured into 150 g of ice water. The pH of the mixture was adjusted to 6 with ammonia, at which point a solid product precipitated. The solid was collected by filtration and the resulting crude product was recrystallized with petroleum ether to give 10 g of yellow solid product in 66.4% yield.

[1] Patent: US2012/289497, 2012, A1. Location in patent: Page/Page column 51-52
[2] Patent: EP2524917, 2012, A1. Location in patent: Page/Page column 58-59
[3] Organic Letters, 2004, vol. 6, # 5, p. 659 - 662
[4] Nucleosides, Nucleotides and Nucleic Acids, 2003, vol. 22, # 12, p. 2133 - 2144