Process for the preparation von oximes cocatalysed by ammonium salts or substituted ammonium salts

Production of oximes by liquid-phase reaction of carbonyl compounds with hydrogen peroxide and ammonia in the presence of a heterogeneous catalyst based on titanium, silicon and oxygen comprises performing the reaction in the presence of a (substituted) ammonium salt homogeneously dissolved in the reaction system. Production of oximes by liquid-phase reaction of carbonyl compounds with hydrogen peroxide and ammonia in the presence of a heterogeneous catalyst based on titanium, silicon and oxygen comprises performing the reaction in the presence of an ammonium salt of formula (I) homogeneously dissolved in the reaction system. (R1R2R3R4)X (I) R1-R4 = H, 1-20C alkyl or 3-12C alicyclic or 6-12C aromatic groups; and X = an anion.