Copper is highly effective for the epoxidation of a “difficult” alkene, whereas silver is not

trans-Methyl styrene, an alkene that contains readily abstractable allylic H atoms, adsorbs with very similar conformations on oxygenated single crystal surfaces of Cu and Ag. Strikingly, however, subsequent reaction on silver leads merely to combustion of the organic molecule, whereas copper is extremely effective in catalyzing the epoxidation of this “difficult” alkene.