Reaktion #320240

Reaktionsgleichung

potassium carbonate

dihydropyran

p-toluenesulfonic acid

epichlorohydrin

1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane

1-acetyloxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane

1-(tetrahydropyranyloxy)-2-acetyloxy-3-chloropropane

1-acetyloxy-3-chloropropan-2-ol

2-acetyloxy-3-chloropropan-1-ol

→

1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane

1-(tetrahydropyran-2-yl)oxy-2-hydroxy-3-chloropropane

Lösungsmittel

methanol

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeto give
2. 2
   Sonstigeto give
3. 3
   SonstigeEvaporation of the methanol, extraction
4. 4
   Sonstigedrying

Vorschrift

1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane can be prepared by the following scheme: epichlorohydrin is reacted with acetic acid in the presence of a catalytic amount of iron trichloride to give a mixture of 1-acetyloxy-3-chloropropan-2-ol and 2-acetyloxy-3-chloropropan-1-ol, the major component. The mixture is treated with dihydropyran in the presence of p-toluenesulfonic acid for five hours at 25° C. to give a mixture of 1-acetyloxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane and 1-(tetrahydropyranyloxy)-2-acetyloxy-3-chloropropane. The mixture is added to a rapidly stirred mixture of aqueous methanol and potassium carbonate at 25° C. and stirred for two hours. Evaporation of the methanol, extraction and drying yields a mixture 1-hydroxy-2-(tetrahydropyran-2-yl)oxy-3-chloropropane and 1-(tetrahydropyran-2-yl)oxy-2-hydroxy-3-chloropropane. Fractional vacuum distillation yields pure 1-hydroxy-2-(tetrahydropyran-2-yl)-oxy-3-chloro-propane since the minor impurity is converted into the more volatile epoxy compound during the distillation procedure.

Quelle