반응 #461796

반응 방정식

acetic anhydride

2-chloro-4-fluoro-4'-methylbenzophenone

disodium hydrogenphosphate

urea hydrogen peroxide

sodium hydrogencarbonate

→

2-chloro-4-fluorobenzoic acid

수율 72.0%

용매

dichloromethane

반응 조건

후처리

1. 1
   기타to warmup to room temperature
2. 2
   추출the aqueous phase was subsequently extracted with dichloromethane
3. 3
   workup.DISTILLATIONThe solvent was then distilled off from the organic phase under vacuum
4. 4
   workup.ADDITION50 g of 70% sulfuric acid were added to the residue (2.5 g, containing ca. 80% of phenyl 2-chloro-4-fluorobenzoate)
5. 5
   온도the mixture was heated for 6 h at the boiling point
6. 6
   추출Dilution of the cooled mixture, extraction with methyl tert-butyl ether
7. 7
   기타drying
8. 8
   기타removal of the solvent and recrystallization of the crude product from water

실험 절차

2.1 g (20 mmol) of acetic anhydride were added dropwise at 0° C. to a mixture of 2.0 g (8 mmol) of 2-chloro-4-fluoro-4'-methylbenzophenone, 9.9 g (0.07 mol) of disodium hydrogenphosphate and 3.8 g (40 mmol) of urea/hydrogen peroxide adduct in 50 ml of dichloromethane. The resulting mixture was then allowed to warmup to room temperature. After 12 h at 20° C., it was neutralized with sodium hydrogencarbonate solution and the aqueous phase was subsequently extracted with dichloromethane. The solvent was then distilled off from the organic phase under vacuum. 50 g of 70% sulfuric acid were added to the residue (2.5 g, containing ca. 80% of phenyl 2-chloro-4-fluorobenzoate) and the mixture was heated for 6 h at the boiling point. Dilution of the cooled mixture, extraction with methyl tert-butyl ether, drying, removal of the solvent and recrystallization of the crude product from water gives 1.0 g (5.7 mmol, 72%) of 2-chloro-4-fluorobenzoic acid in the form of a colorless powder (m.p. 182°-186° C.).

출처