Patent ID: 8779169

Claim:
A process for the preparation of 2-substituted 4-hydroxy-4-methyltetrahydropyrans of the formula (I) where the radical R 1 is a straight-chain or branched alkyl radical having 1 to 5 carbon atoms, and R 2 is hydrogen or a straight-chain or branched alkyl radical having 1 to 3 carbon atoms, which comprises reacting 3-methylbut-3-en-1-ol of the formula (II) with an aldehyde of the formula (III) wherein the radicals R 1 and R 2 have the same meanings as given in formula (I), in the presence of water and in the presence of a strongly acidic cation exchanger to form the compound of the formula (IV) and hydrogenation of the compound of the formula (IV) to give a compound of the formula (I), wherein the hydrogenation is carried out in the presence of hydrogen and a catalyst comprising 30 to 70% by weight of oxygen-containing compounds of nickel, calculated as NiO, 15 to 45% by weight of oxygen-containing compounds of zirconium, calculated as ZrO 2 , 5 to 30% by weight of oxygen-containing compounds of copper, calculated as CuO and 0.1 to 10% by weight of oxygen-containing compounds of molybdenum, calculated as MoO 3 , optionally 0 to 10% by weight of further components, where the data in % by weight refer to the dry, nonreduced catalyst.