反应详情

A 5000 ml 3-neck flask is fitted with a N2 inlet, magnetic stirring bar, thermometer and a Dean-Stark trap with condenser. 2300 ml of dry methanol is added to the flask along with 244 g of 96% H2SO4 and 352 g of trimethyl orthoformate. 173 g of 3-(4'-chlorobenzoyl)-4-hydroxy-6-methyl-2-pyrone is added and the reaction mixture is gently brought to reflux. The most volatile by-product of the reaction (methyl formate) is condensed and collected in the Dean-Stark trap. After 28-281/2 hours of reflux the reaction mixture is cooled to room temperature and poured into 6000 ml of brine. The resulting suspension is extracted with methylene chloride (6×250 ml). Evaporation of the solvent yields 153 g of 3-methoxycarbonyl-6-methyl-2-(4'-chlorophenyl)-4-pyrone. mp (methylene chloride/ether)=131°-132° C.

1. customA 5000 ml 3-neck flask is fitted with a N2 inlet, magnetic stirring bar
2. temperatureto reflux
3. customcondensed
4. customcollected in the Dean-Stark trap
5. temperatureAfter 28-281/2 hours of reflux the reaction mixture
6. additionpoured into 6000 ml of brine
7. extractionThe resulting suspension is extracted with methylene chloride (6×250 ml)
8. customEvaporation of the solvent