The epoxidation of ethylene involves its reaction with oxygen. According to a reaction mechanism suggested in 1974 at least one ethylene molecule is totally oxidized for every six that are converted to ethylene oxide:
The direct reaction of oxygen with alkenes is useful only for this epoxide. Modified heterogeneous silver catalysts are typically employed. Other alkenes fail to react usefully, even propylene, though TS-1 supported Au catalysts can perform propylene epoxidation selectively.