2,3-dichloro-5-(trifluoromethyl)pyridine (DCTF) is an important organic intermediate for the agrochemical industry in particular for use in the synthesis of fluazinam and fluopicolide as well as other pesticidal active pyridine compounds.
Conversion of Nicotinic acid to 2,3-dichloro-5-(trichloromethyl)pyridine. Nicotinic acid (2 g, 16.25 mmole) and phosphorous pentachloride (27 g, 130 mmole) was mixed in a 50 ml Teflon autoclave. The autoclave was closed and heated in a 180 °C warm metal block. After 48 hours was the autoclave cooled to 25 °C and opened. The resulting suspension was quenched in a mixture of NaOH (10 %) and dichlorom ethane under stirring, keeping the temperature below 30 °C. The phases were separated and the organic phase was evaporated to dryness to get the crude product. The product was hereafter distilled and 2,8 g of 2,3-dichloro-5-(trichloromethyl)pyridine was obtained (65% yield).
[1] Patent: CN106748985, 2017, A. Location in patent: Paragraph 0030; 0032; 0033; 0035
[2] Patent: CN107935920, 2018, A. Location in patent: Paragraph 0026; 0031; 0034
