反応 #4359

反応方程式

nitric acid

sulphuric acid

2,4-dichloro-5-fluorobenzoic acid

→

2,4-dichloro-5-fluoro-3-nitro-benzoic acid

溶媒

反応条件

後処理

1. 1
   温度while cooling with ice
2. 2
   その他rises to 45°-50° C
3. 3
   温度The mixture is then heated at 90°-100° C. for a further 3 hours
4. 4
   ろ過the precipitate is filtered off with suction
5. 5
   洗浄washed with water
6. 6
   workup.DISSOLUTIONThe moist crude product is dissolved hot in 30 ml of methanol
7. 7
   workup.ADDITION150 ml of H2O were added to the solution
8. 8
   ろ過The precipitate is filtered off cold with suction
9. 9
   洗浄washed with CH3OH/H2O
10. 10
    その他dried in vacuo at 80° C

実験手順

40 ml of concentrated nitric acid are added dropwise to 34 ml of concentrated sulphuric acid, while cooling with ice and stirring. 20.9 g of 2,4-dichloro-5-fluorobenzoic acid are introduced in portions into this nitration mixture, whereupon the temperature rises to 45°-50° C. The mixture is then heated at 90°-100° C. for a further 3 hours, the mixture is cooled to room temperature and poured onto 350 ml of ice-water and the precipitate is filtered off with suction and washed with water. The moist crude product is dissolved hot in 30 ml of methanol, and 150 ml of H2O were added to the solution. The precipitate is filtered off cold with suction, washed with CH3OH/H2O and dried in vacuo at 80° C. 21.2 g of crude 2,4-dichloro-5-fluoro-3-nitro-benzoic acid are obtained. The compound is sufficiently pure for the subsequent reactions. A sample recrystallized from toluene/petroleum ether gives crystals of melting point 192° C.

出典