Abstract The epoxidation of alkenes was successfully catalyzed by a recyclable catalytic system:[(CH 3 (CH 2) 17) 2 N (CH 3) 2] 3 [PW 4 O 32]/H 2 O 2/dioxan/olefin. This new catalytic system is not only capable of catalyzing homogeneous epoxidation of alkenes with a unique reaction-controlled phase-transfer character, but also avoids the use of chlorinated solvents. The reactions were conducted in a biphasic mixture of aqueous H 2 O 2/dioxan, ...