反应详情

1.76 g (0.044 moles) of a 60% w/w suspension of sodium hydride in mineral oil was added in small portions, whilst stirring and ice-cooling, to a solution of 8.83 g (0.04 moles) of ethyl 2,4,5-trifluoro-3-hydroxybenzoate [(XXIV), X=X'=F, R16 =C2H5O] [prepared as described in step (a) above] in 40 ml of dimethylformamide and, after the addition was complete, the mixture was stirred, whilst ice-cooling, for an additional 30 minutes. At the end of this time, the reaction mixture was transferred into a 200 ml stainless steel autoclave, and then 100 ml of dimethylformamide containing 28.0 g (0.32 moles) of chlorodifluoromethane were added thereto, and the mixture was stirred under pressure at 95°-100° C. for 5 hours. At the end of this time, the dimethylformamide was removed by distillation under reduced pressure, and water was added to the residue, which was extracted with toluene. The extract was washed with water and dried over anhydrous sodium sulfate, and then the solvent was removed by evaporation under reduced pressure. The residue was subjected to silica gel column chromatography, using toluene as the eluent, to give 4.85 g of ethyl 3-difluoromethoxy-2,4,5-trifluorobenzoate as a colorless liquid.

1. additionwas added in small portions
2. additionafter the addition
3. stirringthe mixture was stirred, whilst ice-
4. temperaturecooling, for an additional 30 minutes
5. stirringthe mixture was stirred under pressure at 95°-100° C. for 5 hours
6. customAt the end of this time, the dimethylformamide was removed by distillation under reduced pressure, and water
7. additionwas added to the residue, which
8. extractionwas extracted with toluene
9. washThe extract was washed with water
10. dry with materialdried over anhydrous sodium sulfate
11. customthe solvent was removed by evaporation under reduced pressure