Sulfuric Acid → 5-Trifluoromethylbenzofuroxan

Beteiligte Stoffe

Reaktionsschritte

A solution of 103 grams (0.5 mole) of 4-amino-3-nitro-benzotrifluoride, 750 ml. of acetic acid and 385 ml. of concentrated sulfuric acid is cooled in an ice-bath with sufficient stirring. Sodium nitrite (38 grams, 0.55 moles) is added portionwise at such a rate that the reaction temperature does not exceed 5° C. After addition is complete, 38 grams of urea is added, and with vigoroug stirring 32.5 grams of sodium azide is then added. Stirring is continued for 20 minutes, then the reaction mixture is poured into 4 liters of ice and water. The crude product, 4-azido-3-nitrobenzotrifluoride is extracted from the aqueous mixture with chloroform. The extract is dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to furnish an oily-residue which is taken up in 800 ml. of toluene. The toluene solution is heated under reflux for 18 hours behind a shatter-proof shield. After cooling to room temperature, the solvent is evaporated and the residue is distilled under reduced pressure. The fraction boiling at 105°-108° C. (16 ml.) is considered to be sufficiently pure 5-trifluoromethylbenzofuroxan; yield, 62.3 (60 percent).

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