Science 334, 213–216 (2011)

Alkanes are a major constituent of natural gas and petroleum, but are one of the least chemically reactive classes of organic compounds. As a result, it can be difficult to convert them directly into more useful chemicals in a controlled manner. Gerhard Erker, Harald Fuchs, Lifeng Chi and colleagues at the University of Münster have now shown that a gold surface can be used to carry out precise polymerization reactions of linear alkanes.

Long-chain alkanes that contained more than 20 carbon atoms were adsorbed on a gold(110) surface and imaged with a scanning tunnelling microscope. On heating to around 440 K, the surface reconstructs to form 1.22-nm-wide grooves that constrain the alkane molecules to one-dimensional paths. Moreover, after cooling the surface back down to 78 K, the alkane molecules were found to have bound end-to-end, forming linear molecular chains within the channels

In this thermally activated polymerization process, hydrogen atoms on terminal methyl groups dissociate and desorb from the surface. C–C coupling can then occur between the terminal carbon atoms of neighbouring molecules. The Münster team also show that dehydrogenative C–C coupling can occur between the terminal carbon atom of one molecule and the penultimate carbon atom of a neighbouring molecule.