Uncatalyzed aerobic epoxidation of liquid alkyl alkenes

Abstract

Researchers have investigated for decades a suitable catalyst to selectively synthesize epoxides from alkenes with air. Here we show that a selective aerobic epoxidation of industrial alkyl alkenes in liquid phase occurs without any catalyst, solvent nor additive, just placing the neat alkene under 3–5 bar of O₂ and heating between 100 and 200 °C. The reaction can be performed in either an autoclave, a stirring vessel with air bubbling or even a simple open flask, provided that any metal piece is not in contact with the reaction. Alkyl epoxides are directly obtained, after air venting, in yields and selectivity up to 90%. The simplicity of the set-up (just the neat liquid alkene and air) allows to engage the epoxidation reaction with either a previous alkene formation (upstreaming) or a later epoxide opening (downstreaming) reactions, to achieve a variety of industrially-relevant organic products in one-pot.