A process for preparing an alkylene oxide comprising contacting an alkyl phenyl hydroperoxide with an alkene in an epoxidation reaction to obtain an alkylene oxide and an alkyl phenyl alcohol, wherein the alkyl phenyl hydroperoxide is prepared by a process comprising reacting an alkyl aryl compound and oxygen to produce a reaction mixture comprising alkyl phenyl hydroperoxide, alkyl aryl compound and oxygen; separating at least a part of the reaction mixture into a product stream comprising alkyl phenyl hydroperoxide and an alkyl aryl compound stream; mixing at least a part of the alkyl aryl compound stream with a basic aqueous solution; separating at least a part of the mixture of alkyl aryl compound and basic aqueous solution with the help of a coalescer to obtain an organic phase containing alkyl aryl compound, and an aqueous phase; and recycling at least a part of the organic phase to the reacting step.