2-Fluoro-5-trifluoromethylpyridine

2-Fluoro-5-trifluoromethylpyridine is an important chemical intermediate. By introducing fluorine atoms into the pyridine ring and pyridine side chain, it has strong lipophilicity and can play an important role in pesticides and pharmaceuticals. Its application value and market prospects are very promising.

Colorless liquid

In a 1-liter three-necked flask, 46.20g (0.80 mol) of KF was added, followed by 500 mL of N, N-dimethylacetamide, which was warmed to 125 °C and stirred for 30 minutes. The setup was then connected to a distillation unit for micro-vacuum distillation, during which fractions were collected, and the water content was monitored using three separate bottles. Distillation was halted when the water content reached less than 500 ppm. Subsequently, 7g (0.03 mol) of benzyl triethyl ammonium chloride and 100g (0.55 mol) of 2-chloro-5-trifluoromethylpyridine were added to the flask. A condenser was connected, and the mixture was warmed to 135 °C and stirred for 10 hours. Gas chromatography was used to monitor the reaction; the reaction was stopped when the content of 2-chloro-5-trifluoromethylpyridine in the reaction solution was less than 1%. The reaction solution was directly distilled under reduced pressure to collect the fraction at 40-45 °C / 11 mmHg, yielding 87.80g of 2-fluoro-5-trifluoromethylpyridine with a purity of 98.95% (GC) and a yield of 95.56%.

[1] Patent: CN106866509, 2017, A. Location in patent: Paragraph 0030; 0032; 0044; 0046