反应详情

A mixture of 16 g of 4-amino-3-bromo-2,5-difluorobenzaldehyde and 375 mL of AcOH is stirred until homogenous and 188 mL of 50-52% aqueous hypophosphorous acid is added. Next a solution of 6.8 g of NaNO2 in 38 mL of H2O is added dropwise over 15 minutes with ice cooling to maintain a temperature of 15°-20° C. The ice bath is removed and stirring continued for 1 hour. the reaction mixture is poured into 1 L of ice/H2O and extracted with 3×300 mL of CH2Cl2. The CH2Cl2 extracts are washed with H2O, 2×10% NaOH, and 2×H2O (250 mL each), dried with Na2SO4 and concentrated in vacuo to give 13.32 g (80% yield) of 3-bromo-2,5-difluorobenzaldehyde, m.p. 36°-38° C. Recrystallization from Et2O/hexane furnishes the title compound melting at 37°-40° C. with M+1 ions at 221 and 223 in the mass spectrum.

1. additionis added
2. temperatureto maintain a temperature of 15°-20° C
3. customThe ice bath is removed
4. additionthe reaction mixture is poured into 1 L of ice/H2O
5. extractionextracted with 3×300 mL of CH2Cl2
6. washThe CH2Cl2 extracts are washed with H2O, 2×10% NaOH, and 2×H2O (250 mL each)
7. dry with materialdried with Na2SO4
8. concentrationconcentrated in vacuo