Reaktion #955449

Reaktionsgleichung

sodium nitrite

2-chloro-4-fluoro-3-methylaniline

hydrochloric acid

sodium tetrafluroborate

→

2-chloro-4-fluoro-3-methylbenzenediazonium tetrafluoroborate

Ausbeute 83.6%

Lösungsmittel

water

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   FiltrationThe resultant yellow solution after filtration
2. 2
   Temperaturwas cooled to 0° C. and with stirring sodium tetrafluoroborate (71 g) in water (140 ml)
3. 3
   workup.ADDITIONadded dropwise
4. 4
   SonstigeThe yellow solid formed
5. 5
   Filtrationwas filtered off
6. 6
   Waschenwashed with petroleum ether (6.p 60°-80°)
7. 7
   Sonstigeobtained
8. 8
   workup.ADDITIONby treating the filtrate
9. 9
   TrocknenThe solid was dried overnight over phosphorus pentoxide in vacuo

Vorschrift

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 tetrafluroborate (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 protions each being placed in a round-bottomed flask (250 ml). The flasks were in turn heated with a naked bunsen flame until decomposition 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)

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