反应详情

1000 ml of absolute ethanol, 290 g (0.82 mol) of ethyl 2-(3,4-dimethoxyphenyl)-4-(trifluoromethyl)benzoate and 170 ml (0.164 mol) of 10N sodium hydroxide solution are introduced successively into a 2-liter round-bottomed flask. The reaction mixture is brought to reflux for two hours and then evaporated to dryness under reduced pressure. The residue is taken up in 2.5 liters of water and extracted successively with 500 ml of ethyl acetate and 500 ml of pentane. 500 g of crushed ice are added to the aqueous phase which is then treated with an excess of concentrated hydrochloric acid. The precipitate which forms is filtered on sintered glass and then dried under a stream of air; there is thus obtained 240.5 g (yield: 90%) of 2-(3,4-dimethoxyphenyl)-4-(trifluoromethyl)benzoic acid in the form of a light-beige solid melting at 194° C.

1. temperatureto reflux for two hours
2. customevaporated to dryness under reduced pressure
3. extractionextracted successively with 500 ml of ethyl acetate and 500 ml of pentane
4. addition500 g of crushed ice are added to the aqueous phase which
5. additionis then treated with an excess of concentrated hydrochloric acid
6. filtrationThe precipitate which forms is filtered on sintered glass
7. customdried under a stream of air