Preparation of 1,1,2-trialkoxyethanes

1,1,2-Trialkoxyethanes of the general formula I (I) where R1 to R3 are each independently of the others C1-C20-alkyl or cycloalkyl, or R1 and R2 may be linked together to form a 5-, 6- or 7-membered ring, are prepared by reacting formaldehyde dialkyl acetals of the general formula II (II) where R1 and R2 are each as defined above, or compounds which are capable of forming formaldehyde dialkyl acetals under the reaction conditions, with carbon monoxide, hydrogen and alkanols R3OH under superatmospheric pressure at elevated temperature in the presence of a catalyst composed of a cobalt carbonyl compound and a promotor, wherein the promotor is an alkali metal, alkaline earth metal or ammonium salt of a protogenic compound having an acid constant Ka of from 10-2 to 10-14, an alkali metal or alkaline earth metal hydroxide or an aminocarboxylic acid.