反应详情

To an ice-cooled mixture of 4-hydroxybenzoic acid (13.81 g) in 250 ml of diethylether containing 1.98 g of pyridinium p-toluenesulphonic acid, 3,4-dihydro-2H-pyran (16 g) was drop wise added. After complete addition stirring was continued at temperature below +8° C. for 4 h and the white precipitate was filtered off, washed twice with 100 ml of +4° C. pre-cooled diethylether and dried to give nearly pure 4-(tetrahydro-2H-pyran-2-yloxy)benzoic acid as white powder.

1. additionwise added
2. additionAfter complete addition
3. filtrationthe white precipitate was filtered off
4. washwashed twice with 100 ml of +4° C.
5. temperaturepre-cooled diethylether
6. customdried