Patent number: 5648551
Abstract: The invention relates to a process for the preparation of halobenzaldehydes of the formula (I): ##STR1## in which Hal is fluorine, chlorine, bromine or iodine and z=1, 2, 3 or 4, by catalytic gas-phase oxidation of a substituted toluene of the formula (II), ##STR2## by oxygen, which comprises carrying out the oxidation in the presence of a catalyst of the formula (III)Me.sup.1.sub.a Me.sup.2.sub.b Me.sup.3.sub.c O.sub.x (III),in which Me.sup.1 is bismuth or vanadium, Me.sup.2 is at least one of the elements selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, Me.sup.3 is at least one element selected from the group consisting of iron, cobalt, nickel, niobium, molybdenum, arsenic, tin, antimony, tungsten, tantalum, phosphorus, chromium, manganese, palladium, copper, zinc, cerium, silver, boron, samarium, barium, calcium, magnesium and rhenium, and the letters a, b and c represent an atomic ratio of the respective elements such that when a=1, b has a value in the range from 0.
Type:
Grant
Filed:
January 26, 1996
Date of Patent:
July 15, 1997
Assignee:
Hoechst Aktiengesellschaft
Inventors:
Holger Borchert, Thomas Gerdau, Jens Weiguny