反应详情

0.030 g of p-toluenesulphonic acid and 17.8 g of 3,4-dihydro-2H-pyrane are added to a mixture of 29.8 g of 2,3-dihydroxy-nitrobenzene in 400 ml of absolute benzene and the solution is left to stand for 7 days at 20°. It is filtered through 15 g of a silica gel formulation (Merck silica gel 60; grain size 0.063-0.200 mm) and the silica gel is rinsed with benzene. After distilling off the benzene under reduced pressure, a reddish oil is obtained which, when crystallised from hexane, gives 2-hydroxy-3-(tetrahydropyran-2-yloxy)-nitrobenzene in the form of yellow crystals; melting point 72°-73°.

1. waitthe solution is left
2. filtrationIt is filtered through 15 g of a silica gel formulation (Merck silica gel 60; grain size 0.063-0.200 mm)
3. washthe silica gel is rinsed with benzene
4. distillationAfter distilling off the benzene under reduced pressure
5. customa reddish oil is obtained which, when
6. customcrystallised from hexane