反应详情

26.8 g (0.1 mol) of 2,4-dichloro-5-fluorobenzophenone are dissolved in 250 g of 96% sulfuric acid, and 17 g of 30% hydrogen peroxide solution are added at 0° C., with thorough mixing, in such a way that the temperature does not exceed 40° C. When the metered addition is complete, the temperature is allowed to drop to 20° C. and the mixture is stirred for 5 h at this temperature. If the conversion is incomplete, a further 5 g of hydrogen peroxide solution are metered in (T<40° C.) and the mixture is diluted with 1000 g of water after a further 3 h of reaction time and is subsequently stirred for 2 h. The 2,4-dichloro-5-fluorobenzoic acid which has precipitated out is filtered off and purified by recrystallization (water) to give 17.8 g (0.0852 mol, 85%) of 2,4-dichloro-5-fluorobenzoic acid melting at 144°-146° C.

1. customdoes not exceed 40° C
2. additionWhen the metered addition
3. customto drop to 20° C.
4. customare metered in (T<40° C.)
5. stirringis subsequently stirred for 2 h
6. customThe 2,4-dichloro-5-fluorobenzoic acid which has precipitated out
7. filtrationis filtered off
8. custompurified by recrystallization (water)