The present invention is related to a process for purifying propylene oxide, comprising (i) providing a stream SO comprising propylene oxide, acetonitrile, water, and an organic compound comprising acarbonyl group -C(=O)-, wherein said organic compound comprising a carbonyl group -C(=O)- comprises one or more of acetone and propionaldehyde; (ii) separating propylene oxide from the stream SO by distillation, comprising (11.1) subjecting the stream S0 to distillation conditions in a first distillation unit, obtaining a gaseous top stream S1 c which is enriched in propylene oxide compared to thestream S0, a liquid bottoms stream S1a which is enriched in acetonitrile and water compared to the stream S0, and a side stream S1b comprising propylene oxide which is enriched in the carbonyl compound compared to the stream S0; (11.2) reacting the carbonyl compound comprised in the side stream S1b with an organic compound comprising an amino group -NH2 obtaining a reaction product of the organiccompound comprising a carbonyl group and the organic compound comprising an amino group; (11.3) separating propylene oxide from the reaction product of the organic compound comprising a carbonyl group and the organic compound comprising an amino group in a second distillation unit, obtaining a gaseous top stream S3a which is enriched in propylene oxide and a liquid bottoms stream S3b which is enriched in the reaction product of the organic compound comprising a carbonyl group and the organic compound comprising an amino group; (11.4) introducing the top stream S3a which is enriched in propylene oxide propylene oxide into the first distillation unit.