the mixing device where additional water is added if necessary thus the process of the present invention provides an efficient process for the direct oxidation of propylene to propylene oxide using molecular oxygen wherein the concentration of organic acid impurities is substantially reduced in the reaction zone thereby avoiding the drawbacks of prior art processes noted above the present invention will be further illustrated by reference to the following examples which are intended to be illustrative and not limiting in effect the apparatus used was composed of titanium and includes the elements shown in the figure into a 10 liter reactor was introduced per hour the temperature was kept at 163 u00b0 c and the pressure at 60 bars the residence time of the reaction phase in the reactor was 0 38 hour gases escaping from the reactor were cooled down to 20 u00b0 c in condenser b i e a separation into an gas phase and a liquid phase is realized in condenser b the gases vented from the condenser have a flow rate of 2 419 m 3 hr and have the composition shown in table 1 the liquid phase was fed to a decantation device having a volume of 0 3 liter no additional water being added thereto the lower aqueous phase is drawn off continuously from the decantation apparatus d and its composition is given in table 1 the upper phase rich in propylene was recycled to the reactor so as to maintain the level of reaction mixture constant 19 442 kg per hour of an organic phase the composition of which is given in table 1 was drawn off from the reactor stream 10 in table 1 as in the following tables the following are included in the 34 various.