3,5,6-Trichloro-2-pyridinol

2402-79-1

6515-38-4

The general procedure for the synthesis of 3,5,6-trichloropyridin-2(1H)-one from 2,3,5,6-tetrachloropyridine: 2,3,5,6-tetrachloropyridine 43.4g (0.2 mol) and 240mL of deionized water were added into a three-necked flask, and the temperature was raised to 95℃ under stirring. Subsequently, 39.53 g (0.60 mol, 85% purity) of potassium hydroxide was slowly added and the pH of the reaction solution was adjusted to 9.5~10. Stirring was maintained at this temperature for 30 min, and the reaction was completed by filtration while hot to remove insoluble impurities. The filtrate was transferred to a 500 mL autoclave and 0.18 g of potassium hydroxide and benzyltrimethylammonium chloride were added as phase transfer catalyst. The autoclave was sealed, the reaction mixture was stirred and heated to 120 °C and kept at this temperature for 4.0 hours. At the end of the reaction, the reaction was cooled to 25 °C and the pH was adjusted to 4.0~4.5 with 15% hydrochloric acid solution. the reaction mixture was filtered and the resulting solid was washed with deionized water and dried to give 35.9 g of a white powdery product 3,5,6-trichloropyridin-2(1H)-one. The purity of the product was 99.08% by gas chromatography.