GB871830A - Method for the simultaneous production of hydrogen peroxide and carbonyl compounds - Google Patents

Abstract

Hydrogen peroxide is produced together with a carbonyl compound by the oxidation of a primary or secondary alcohol in the liquid phase with an oxygen-containing gas in the presence of titanium dioxide and ultraviolet light having a wave lenght of 3000-4000 A, e.g. as produced by a mercury lamp. The alcohol may be an aliphatic, aromatic, or hydroaromatic alcohol, e.g. ethanol, isopropanol, benzyl alcohol, or cyclohexanol. Less than 10%, e.g. 1%, of titanium dioxide may be employed. The temperature of reaction may be 50-150 DEG C. The oxygen partial pressure is preferably above 100 mm. of Hg., and may for example be 2 atmos. The reaction vessel may be of glass, aluminium, an alloy of aluminium, tin, porcelain, or another material coated with one of said materials or enamel or a resin. The process may be carried out continuously or intermittently in a reaction vessel provided with reflux condenser and stirrer. Alternatively the reactants and titanium dioxide may be passed continuously through a quartz tube irradiated with ultra-violet light. The concentration of the hydrogen peroxide produced is preferably below 25%. The titanium dioxide may be removed from the reaction products by centrifuging, filtering, or settling. The hydrogen peroxide and carbonyl compound may be separated by fractional distillation, precipitation of the hydrogen peroxide as a metal peroxide, solvent extraction of the carbonyl compound, or by forming an addition compound of the carbonyl compound. In the examples (a) isopropanol and (b) cyclohexanol are treated according to the process claimed to give hydrogen peroxide and (a) acetone and (b) cyclohexanone respectively. In Example 2 a method of separating the acetone from the reaction product is given in which the product is diluted with water containing sodium pyrophosphate and 8-oxyquinoline and the acetone is separated from the resulting mixture by vacuum distillation.ALSO:Hydrogen peroxide is produced together with a carbonyl compound by the oxidation of a primary or secondary alcohol in the liquid phase with an oxygen-containing gas in the presence of titanium dioxide and ultraviolet light having a wavelength of 3000-4000 A, e.g. as produced by a mercury lamp. The alcohol may be an aliphatic, aromatic, or hydroaromatic alcohol, e.g. ethanol, isopropanol, benzyl alcohol, cyclohexanol, benzhydrol, or a -1,2,3,4-tetrahydronaphthol. Less than 10%, e.g. 1%, of titanium dioxide may be employed. The temperature of reaction may be 50-150 DEG C. The oxygen partial pressure is preferably above 100 mm. Hg., and may for example be 2 atmos. The reaction vessel may be of glass, aluminium, an alloy of aluminium, tin, porcelain, or another material coated with one of said materials or enamel or a resin. The process may be carried out continuously or intermittently in a reaction vessel provided with reflux condenser and stirrer. Alternatively the reactants and titanium dioxide may be passed continuously through a quartz tube irradiated with ultraviolet light. The concentration of the hydrogen peroxide produced is preferably below 25%. The titanium dioxide may be removed from the reaction products by centrifuging, filtering, or settling. The hydrogen peroxide and carbonyl compound may be separated by fractional distillation, precipitation of the hydrogen peroxide as a metal peroxide, solvent extraction of the carbonyl compound, or by forming an addition compound of the carbonyl compound. Three examples specifying conditions of reaction are given. According to Example 2, the liquid reaction product is diluted with half its volume of an aqueous solution of sodium pyrophosphate and 8-oxyquinoline, and acetone and isopropanol removed by vacuum distillation leaving a 25% solution of hydrogen peroxide. According to Example 3, the liquid reaction product is diluted with an equal volume of benzene, the hydrogen peroxide is extracted with 0.2 vols. of water giving an 8.5% aqueous solution, and the cyclohexanone also produced is extracted with a 5% aqueous solution of sodium bisulphite and recovered by the addition of potassium carbonate. The unreacted cyclohexanol is recovered from the benzene by distillation.