Various oxides, such as thoria, alumina, and the blue oxide of tungsten, exert a dehydrating action on ethyl and other alcohols at a temperature of 300-350°, the products being ethylene hydrocarbons, almost exclusively. In some cases, the dehydration may be restricted at lower temperatures, and the ethers formed. Sabatier and Mailhe1 have pointed out that the mechanism of this reaction is strictly analogous to the dehydration of alcohol which is effected by sulphuric acid. The analogy is further illustrated by the fact that the oxides in question act as esterifying catalysts: thus if a mixture of the vapours of ethyl alcohol and acetic acid is passed over titanium dioxide at 300°, a good quantity of ethyl acetate is produced.

Similarly, alcohols and ammonia passed over heated thorium oxide yield the corresponding amines; and alcohols with hydrogen sulphide give thiols.