A process for the catalytic preparation of halobenzaldehydes and catalysts for carrying out the method

The invention relates to a process for the preparation of halobenzaldehydes by catalytic gas-phase oxidation of a substituted toluene with oxygen and to novel catalysts of formula (III), which can be used in the preparation of halobenzaldehydes. DOLLAR A Me · 1 · ¶a¶Me · 2 · ¶b¶Me · 3 · ¶c¶O¶x¶ (III) wherein A DOLLAR DOLLAR A Me · 1 · for at least one of the elements from the group lithium, sodium , potassium, rubidium, cesium, antimony, cerium, or bismuth, DOLLAR a Me · 2 · for at least one of the elements from the group iron, cobalt, nickel, tin, tungsten, rhenium, tantalum, palladium, phosphorus, chromium, manganese, copper , zinc, silver, boron, samarium, barium, calcium, magnesium, tellurium or selenium and DOLLAR a Me · 3 · for at least one of the elements from the group vanadium, molybdenum or niobium is DOLLAR a and the atomic ratio of the respective elements, based on c = 1, is independently a 0 to 0.6 and b 0 to 0.7, wherein the ratio (a + b) / c is between 0.2 and 0.9, and free valences with positive x oxygen atoms are saturated.