1-Chloro-2-nitrobenzene → 1-Fluoro-2-nitrobenzene

Participants

Reaction Steps

A finely ground mixture of potassium fluoride (11.62 g, 0.2 mole) and CsF-silica (5 g, ca. 5 mmole equiv. F) is dried at 150° C. and then immediately transferred to a three-necked flask containing 2-chloronitrobenzene (7.88 g, 0.05 mole) and dimethylformamide. The flask is connected to a water-condenser and a mechanical stirrer and the reaction mixture is brought to reflux with vigorous stirring. After 24 h. the reaction mixture is cooled and separated into its ether- and water-soluble components. Chloride analysis of the aqueous extracts (AgNO3 titration, K2CrO4 indicator) shows better than 60% conversion of the 2-chloronitrobenzene. The ethereal extracts are washed with water (to remove the D.M.F.), dried over anhydrous Na2SO4, evaporated to dryness on a rotary evaporator and distilled under reduced pressure to give 3.7 g (52%) of 2-fluoronitrobenzene, b.p. 68°-70° C. (4 Torr). When the same reaction is carried out using (i) a dried mixture of KF (11.62 g) and CsF (0.75 g) and (ii) dried KF (11.62 g) alone in place of the KF-CsF-silica mix, chloride analysis of the aqueous extracts shows ca. 60% and ca. 20% conversion of 2-chloronitrobenzene respectively.

Provenance & Evidence