GB1115186A - Epoxidation process - Google Patents

Abstract

Epoxides are made by reacting an olefinically unsaturated compound with an aralkyl hydroperoxide, derived from an aralkane having at least one hydrogen atom on a carbon adjacent to the aromatic ring system, in the liquid phase in the presence of a metal epoxidation catalyst to produce a product mixture containing unreacted hydroperoxide, in addition to an epoxy compound and the alcohol formed from the hydroperoxide, reacting the unreacted hydroperoxide with hydrogen to reduce it to the corresponding alcohol and recovering the epoxy compound, either before or after reduction of the unreacted hydroperoxide, the total amount of hydroperoxide fed to the reaction being 0.01-50 mols per mol olefinic group in the unsaturated reactant. The preferred catalysts are compounds of V, Mo, W and Se, particularly organic compounds which are soluble in the reaction medium. Cumene and ethylbenzene hydroperoxides are the preferred hydroperoxides. The olefinic reactant may be an olefine or an unsaturated ether, ester, alcohol, ketone or halide. The epoxide may be removed from the product mixture before the hydrogenation step which may then be effected at, e.g. temperatures below 100 DEG C. and pressures below 500 p.s.i.g. in the presence of a Pd hydrogenation catalyst. If the epoxide remains in product mixture, hydrogenation should be effected under milder conditions, e.g. at temperatures below 60 DEG C. and pressures below 500 p.s.i.g. preferably using a Ni/kieselguhr catalyst. During the reduction of the hydroperoxide the alcohol produced in the epoxidation reaction may be hydrogenated to the corresponding aralkane. This aralkane may be oxidized with molecular oxygen in the presence of an oxidation initiator to yield the corresponding aralkyl hydroperoxide which may be recycled to the epoxidation stage. Examples relate to the preparation of propylene oxide using cumene hydroperoxide, the unreacted portion of which is reduced to cumyl alcohol with co-production of cumene which is oxidized in the presence of t-butylperbenzoate to cumene hydroperoxide.