反应详情

A solution of 6.2 g (24.5 mmole) of 5-fluoro-2-nitro-4-trifluoromethyl-benzoic acid in 250 ml of methanol is treated with 9.28 ml (73.5 mmole) of trimethylchlorosilane and heated to reflux for six days during which every evening additional 9.28 ml of trimethylchlorosilane are added. The cooled solution is evaporated in vacuo and distributed between dichloro-methane and water. The combined organic phases are extracted twice with 50 ml of a 0.5 M sodium hydroxide solution and with 50 ml brine. After drying over sodium sulfate, filtering and evaporation the crystalline residue is recrystallized from acetone/petrolether to give 5-fluoro-2-nitro-4-trifluoromethyl-benzoic acid methyl ester of m.p. 66-68° C.

1. temperatureheated
2. additionare added
3. customThe cooled solution is evaporated in vacuo
4. extractionThe combined organic phases are extracted twice with 50 ml of a 0.5 M sodium hydroxide solution and with 50 ml brine
5. dry with materialAfter drying over sodium sulfate
6. filtrationfiltering
7. customevaporation the crystalline residue
8. customis recrystallized from acetone/petrolether