Alkyl Iodides on Copper Surfaces: C-H Activation and Coupling Reactions of Hydrocarbon Fragments to Produce Ethylene

The dissociative adsorption of alkyl iodides onto a Cu(100) surface under ultra-high vacuum conditions has been utilized to generate and study the chemistry of adsorbed hydrocarbon fragments. It is found that iodomethane, iodoethane, and diiodomethane all react to produce, among other hydrocarbon products, ethylene. The surface reaction mechanisms, as determined by thermal desorption and isotope labelling studies, include: α-elimination from methyl groups, β-hydride elimination from ethyl groups, methylene coupling, and methylene insertion into methyl groups.