Patent GB-845038-A (GB)
Title: Improvements in and relating to the oxidation of organic compounds
Inventor: WHITFIELD GORDON HOWARD
IPC: C07C51/34
Filed: 1958-01-27
Abstract: In processes for the oxidation of organic compounds in the liquid phase by means of oxygen or ozone carried out in a reactor having inner surfaces of metal (but excluding processes wherein a non-aromatic carboxylic acid forms part of the reaction-mixture and only a stainless steel reactor is available), corrosion of the metal surfaces is prevented by adding a fluoride to the reaction-mixture so as to provide a concentration of fluoride-ion of 0,004 to 1,0% by weight of the reaction mixture.  The fluoride ion may be introduced as hydrofluoric acid or as sodium chloride.  The process is suitable for oxidations carried out in the presence of a catalytic amount of a metal ion of variable valency, and of the bromide ion, e.g. by using cobalt and/or manganese bromide as catalyst.  The process is suitable for the production of organic carboxylic acids, e.g. the xylenes or the di-isopropyl benzenes may be oxidized to the corresponding phthalic acids; toluene and benzyl alcohol yield benzoic acid; the methyl naphthalenes yield the naphthoic acids; mesitylene yields trimesic acid; methyl-p-toluate yields methyl hydrogen terephthalate; and the methyl pyridines yield the corresponding pyridinic acids. Many other starting-materials for the production of carboxylic acids are specified in the Specification.  Using reactors of aluminium or aluminium alloys, cyclohexane or cyclohexanone may be oxidized to adipic acid; methylcyclohexane may be oxidized to yield glutaric and succinic acids; and pentane may be oxidised to yield butyric, propionic, acetic and formic acids.  The Specification includes data relating to the corrosion of titanium-steel, titanium-molybdenum-steel, aluminium, aluminium-manganese alloy, aluminiummagnesium alloy, and titanium when present in the reactor during the oxidation of o- or pxylene, catalysed by cobalt and manganese bromides, using as solvent either benzoic acid or propionic acid.  In some tests, no fluoride ion was present, but in others sodium fluoride was added to provide fluoride concentrations ranging from 0,01 to 1,0% by weight of the reaction mixture.ALSO:In processes for the oxidation of organic compounds in the liquid phase by means of oxygen or ozone carried out in a reactor having inner surfaces of metal (but excluding processes wherein a non-aromatic carboxylic acid forms part of the reaction-mixture and only a stainless steel reactor is available), corrosion of the metal surfaces is prevented by adding a fluoride to the reaction-mixture so as to provide a concentration of fluorideion of 0.004 to 1.0% by weight of the reaction mixture. The fluoride-ion may be introduced as hydrofluoric acid or as sodium fluoride. The Specification includes data relating to the corrosion of titanium-steel, titanium-molybdenum-steel, aluminium, aluminium-manganese alloy, aluminium - magnesium alloy, and titanium when present in the reactor during the oxidation of o- or p-xylene, catalysed by cobalt and manganese bromides, using as solvent either benzoic acid or propionic acid.  In some tests, no fluoride-ion was present, but in others sodium fluoride was added to provide fluoride concentrations ranging from 0.01 to 1.0% by weight of the charge.