反应详情

温度

5 °C

2-chloro-4-fluoro-3-methylaniline (73 g) was added dropwise, with vigorous stirring to 50% hydrochloric acid (256 ml). The resulting white suspension was cooled to 5° C. and with stirring, sodium nitrite (34.5 g) in water (50 ml), added dropwise. The resultant yellow solution after filtration was cooled to 0° C. and with stirring sodium tetrafluoroborate (71 g) in water (140 ml), added dropwise. The yellow solid formed was filtered off and washed with petroleum ether (6.p 60°-80°) and combined with further similarly washed solid obtained by treating the filtrate, maintained at 0° C., with sodium tetrafluoroborate (71 g) in water (140 ml). The solid was dried overnight over phosphorus pentoxide in vacuo, giving a yield of 98.8 g 2-chloro-4-fluoro-3-methylbenzenediazonium tetrafluoroborate. This was divided into three portions each being placed in a round-bottomed flask (250 ml). The flasks were in turn heated with a naked bunsen flame until decompositio set in and an orange vapor was emitted, which was condensed and collected in a cooled receiver. The orange oil obtained from the three batches was dissolved in diethyl ether (200 ml) and washed with aqueous sodium hydroxide solution (10%, 300 ml) then saturated brine (200 ml). After drying the ethereal solution over anhydrous magnesium sulphate, filtering and evaporating at atmospheric pressure, the residual oil was distilled to give 2-chloro-3,6-difluorotoluene (45 g)

1. filtrationThe resultant yellow solution after filtration
2. temperaturewas cooled to 0° C. and with stirring sodium tetrafluoroborate (71 g) in water (140 ml)
3. additionadded dropwise
4. customThe yellow solid formed
5. filtrationwas filtered off
6. washwashed with petroleum ether (6.p 60°-80°)
7. customobtained
8. additionby treating the filtrate
9. dry with materialThe solid was dried overnight over phosphorus pentoxide in vacuo