A continuous process for the preparation of propylene oxide, comprising (a) reacting propene, optionally admixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining a stream S0 leaving the reaction apparatus, S0 containing propylene oxide, acetonitrile, water, at least one further component B, optionally propene and optionally propane, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and wherein the decadic logarithm of the octanol-water partition coefficient (log K OW) of the at least one component B is greater than zero; (b) separating propylene oxide from S0, optionally after having separated propene and optionally propane, obtaining a stream S1 containing acetonitrile, water and the at least one further component B; (c) dividing S1 into two streams S2 and S3, wherein the total weight of S3 relative to the total weight of S1 is in the range of from 0.01 to 25 %; (d) subjecting S3 to a vapor-liquid fractionation in a first fractionation unit, obtaining a vapor fraction stream S4a being depleted, relative to S3, of at least one of the at least one component B and obtaining a liquid bottoms stream S4b, and subjecting at least part of the vapor fraction stream S4a to a vapor-liquid fractionation in a second fractionation unit, obtaining a vapor fraction stream S4c and a liquid bottoms stream S4 being depleted, relative to S4a, of at least one of the at least one component B; (e) recycling at least a portion of S4, optionally after work-up, to (a), and recycling at least a portion of S2, optionally after work-up, to (a). (a) reacting propene, optionally admixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining a stream S0 leaving the reaction apparatus, S0 containing propylene oxide, acetonitrile, water, at least one further component B, optionally propene and optionally propane, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and wherein the decadic logarithm of the octanol-water partition coefficient (log K OW) of the at least one component B is greater than zero; (b) separating propylene oxide from S0, optionally after having separated propene and optionally propane, obtaining a stream S1 containing acetonitrile, water and the at least one further component B; (c) dividing S1 into two streams S2 and S3, wherein the total weight of S3 relative to the total weight of S1 is in the range of from 0.01 to 25 %; (d) subjecting S3 to a vapor-liquid fractionation in a first fractionation unit, obtaining a vapor fraction stream S4a being depleted, relative to S3, of at least one of the at least one component B and obtaining a liquid bottoms stream S4b, and subjecting at least part of the vapor fraction stream S4a to a vapor-liquid fractionation in a second fractionation unit, obtaining a vapor fraction stream S4c and a liquid bottoms stream S4 being depleted, relative to S4a, of at least one of the at least one component B; (e) recycling at least a portion of S4, optionally after work-up, to (a), and recycling at least a portion of S2, optionally after work-up, to (a).