Fremgangsmåde til fremstilling af 3-hydroxyalkanaler

The invention relates to a process for the preparation of 3-hydroxyalkanals having 3 to 12, in particular 3 or 4, C atoms, by hydration of the basic 2-alkenals with water in a homogeneous phase in the presence of an acidic catalyst. The previously known hydration by means of mineral acids or carboxylic acids as catalyst results in poor space-time yields and/or poor selectivities. These disadvantages can be avoided when a dissolved acid/base buffer is used as catalyst which results in a pH of 2 to 5 in the reaction mixture and whose acid component and the corresponding base are present in the reaction mixture in an amount of 0.5 to 40% by weight in total. The preferred buffers composed of a lower monobasic carboxylic acid and a tertiary amine can be recycled in a simple manner.