Linear Alkanes Polymerize On Gold

Long-chain alkanes can polymerize predictably at moderate temperatures on a cor­rugated gold surface, according to researchers in Germany who made the discovery (Science, DOI: 10.1126/​science.1211836). The work adds to the growing list of catalytic transformations mediated by gold and could lead to less expensive polymers by avoiding functionalized starting materials such as alkenes. The study also highlights the mechanistic role of molecular-scale surface structure in reactions involving solid catalysts. The University of Münster’s Dingyong Zhong, Harald Fuchs, Lifeng Chi, and coworkers report that 1.22-nm-wide grooves that form on a gold surface as a result of a process known as surface reconstruction limit the diffusion of long alkanes such as n-dotriacontane, CH₃(CH₂)₃₀CH₃, to the one-dimensional channels. On the basis of scanning tunneling microscopy and other types of analysis, the group concludes that the surface confinement activates the molecule’s C–H bonds at selective sites—specifically at the terminal CH₃ and penultimate CH₂ groups. This process leads to loss of hydrogen followed by C–C coupling reactions that join the monomers end to end, the researchers say.