反应详情

温度

-5 °C

A mixture of 2,5-difluorotoluene (25 g, 0.20 mol) and iron powder (11 g, 0.2 mol) was cooled to −5° C. Bromine was added dropwise such that the internal temperature of the reaction did not rise above 0° C. After stirring for 3 hours, the mixture was diluted with ether, filtered and washed with aqueous sodium thiosulfate solution. The aqueous layer was extracted with ether, and the combined organic layers were dried over MgSO4, filtered and concentrated in vacuo. Distillation at atmospheric pressure gave 34 g of 1-bromo-2,5-difluoro-4-methyl-benzene as a colorless oil (b.p. 180 oC). 1H NMR (300 MHz, CDCl3) δ 7.20 (dd, 1H, J=6.0, 8.5 Hz), 6.93 (m, 1H), 2.23 (s, 3H) ppm.

1. customdid not rise above 0° C
2. filtrationfiltered
3. washwashed with aqueous sodium thiosulfate solution
4. extractionThe aqueous layer was extracted with ether
5. dry with materialthe combined organic layers were dried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. distillationDistillation at atmospheric pressure