Abstract: Tert.-Amyl alcohol (TAA) can be prepared in an advantageous manner by hydrating of i-amylenes on an acid cation exchanger by carrying out the reaction in the vicinity of the boiling point of the i-amylenes under the appropriate reaction pressure. A higher content of TAA is thereby obtained in the reaction mixture.

Abstract: Crosslinked organic resins, containing SiO.sub.2 and sulphonic acid groups, having an SiO.sub.2 content of 0.1-10% by weight, relative to the total weight of the SiO.sub.2 -containing resins, are prepared by steeping crosslinked organic resins, containing sulphonic acid groups, in the alkali form in aqueous alkali metal silicate solutions or (quaternary) alkylammonium silicate solutions, and subsequently precipitating the SiO.sub.2 using mineral acid, and simultaneously converting the resin into the H.sup.+ form. These resins can be used as acid catalysts in the cleavage of tert.-alkyl ethers into the basic tertiary olefins and the basic alkanols. This use has proven particularly advantageous when the tert.-alkyl alkyl ethers to be cleaved are employed together with water for the cleavage.