Dehydration of alcohols catalysed by metallic sulphates supported on silica gel

Abstract

Many metallic sulphates and hydrogen sulphates supported on silica gel efficiently catalyse dehydration of secondary and tertiary alcohols under mild conditions. The sulphates of Ce^IV, Ti^IV, and Fe^III were most active. Silica gel was essential for the efficient dehydration in each case. The dehydration catalysed by Fe₂(SO₄)₃, CuSO₄, and NaHSO₄ on silica gel was studied in detail. The order of the reactivity of alcohols was tertiary > secondary > primary. The dehydration activity of methanesulphonic acid was also enhanced (ca. 14 times at 90 °C) by the presence of silica gel. Some mechanistic investigations were carried out.