Preparation of aromatic carbonyl compounds by catalytic oxidation with molecular oxygen

A process for the preparation of an aromatic carbonyl compound of formula I,

• wherein
• X is cyano, 5-(trifluoromethyl)-1,2,4-oxadiazole-3-yl, nitro, halogen, CF3, —C(═O)—C1-C6-alkyl, —S(═O)2—C1-C6-alkyl, or —C(═O)—O—C1-C6-alkyl;
• R is halogen;
• n is 0 or 1;
• Y is OH or C1-C6-alkyl;
• the process comprising reacting a compound of formula II,
• wherein Ya is hydrogen or C1-C6-alkyl;
• and wherein the variables X, R, and n are as defined above for compounds of formula I, with molecular oxygen in the presence of a solvent, a cobalt(II) salt, and N,N′,N″-trihydroxyisocyanuric acid;
• and wherein the solvent is propionic acid or acetic acid;
• at a temperature between 70° C. and 200° C.;
• and wherein an amount of N,N′,N″-trihydroxyisocyanuric acid is less than 2 mol %, based on an amount of compound II, and a ratio of the cobalt atoms to N,N′,N″-trihydroxyisocyanuric acid is at least 1.