In a loop reactor, an alkylene oxide is reacted with an organic compound having a reactive hydrogen atom, where a gas circuit (5,7,4) and a liquid circuit (2,3,4) are arranged around the reactor (1) and coupled to each other via a jet intake mixing nozzle (4). Crucial for the completeness of the reaction and for the suppression of the formation of by-products, such as dioxane, is a reduction.