Nitric Acid → 4,5-Difluoro-2-nitrobenzaldehyde

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Reaction Conditions

Reaction Steps

To 520 cm3 of sulphuric acid, cooled to 0° C., are added, with stirring, 60 cm3 of fuming nitric acid, over 30 minutes. 100 g of 3,4-difluorobenzaldehyde are added over 30 minutes at approximately 0° C. to the solution obtained. The temperature is allowed to return to approximately 20° C. and stirring is continued for 3 hours at this temperature. After cooling to approximately 5° C., the reaction mixture is poured, over 30 minutes and with vigorous stirring, onto 1200 g of crushed ice. The temperature is allowed to return to approximately 20° C., followed by extraction with twice 600 cm3 of toluene. The combined organic extracts are washed with 3 times 1000 cm3 of water, and concentrated under reduced pressure (20 kPa) at 50° C. 113 g of 3,4-difluoro-6-nitrobenzaldehyde are obtained in the form of a brown oil, which is used as it is in the subsequent syntheses. A purified sample of 3,4-difluoro-6-nitrobenzaldehyde gives the following characteristics:

Provenance & Evidence