Abstract: The epoxidation of terminally and/or internally olefinically unsaturated hydrocarbon compounds which are liquid at 50.degree. to 100.degree. C. and at atmospheric pressure (oil phase), in which the oil phase is treated with an acid phase containing acetic acid, hydrogen peroxide and peracetic acid in aqueous solution, after which the aqueous acid phase is separated from the oil phase, the peracetic acid in the aqueous acid phase is regenerated and the regenerated aqueous acid phase is returned to the epoxidation reactor. Epoxidation is carried out using an aqueous acid phase containing at most about 10% by weight of peracetic acid, and the peracetic acid content in the aqueous acid phase is reduced by at most about 50%, based on the peracetic acid content of the aqueous acid phase used, after a single passage through the epoxidation stage. After separation from the oil phase, the aqueous acid phase preferably is cooled before regeneration.

Abstract: In a multistage process for the continuous epoxidation of double bonds of terminal and non-terminal olefins containing more than 12 carbon atoms, unsaturated higher fatty acids and their lower alkanol and lower alkanediol esters and also unsaturated fatty alcohols containing from 8 to 18, preferably 18, carbon atoms and triglycerides of higher fatty acids including unsaturated fatty acids, preferably soyabean oil, using performic acid formed in situ from hydrogen peroxide and formic acid, the reactants, olefin and hydrogen peroxide/formic acid, are passed at ambient pressure in cross-counter flow through an at least three-stage reaction cascade. The olefinic phase is introduced into the first reaction stage, the hydrogen peroxide and the formic acid are introduced in separate streams into the penultimate reaction stage and the olefin phase and the hydrogen peroxide/formic acid phase (acid water phase) are separated from one another in a phase separator after each reaction stage.