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Journal of the Electrochemical Society, Vol.156, No.12, E171-E178, 2009
Reactivity of Long Chain alpha,omega-Dibromoalkanes at Palladized Solid Cathodes: Homocoupling vs Oligomerization
Copper-palladium (Cu-Pd) and silver-palladium (Ag-Pd) systems are used as cathode materials for reducing long chain alpha,omega-dibromoalkanes [Br-(CH2)(n)-Br] with n > 3. Such interfaces globally permit the cleavage of the two C-Br bonds in a single two-electron process. A spectacular potential shift (Delta E) is obtained in comparison with glassy carbon electrodes at which the total reduction corresponds to a four-electron process. Such potential shifts are typically of the order of 1 V. In particular, cathodic reactions are easily achieved at Ag-Pd interfaces. Under these conditions, supporting evidences are given for the formation (according to simultaneous or sequenced processes) of a transient alpha,omega-biradical with different lengths of the alkyl chain (6 < n < 12). Macroelectrolysis data show that palladized interface reactions give rise to heterogeneous couplings and, markedly, the formation of homodimers. Reductions of alpha,omega-dibromoalkanes in the presence of copper-palladium, palladium, and silver palladium fine powders efficiently induce the deposit of Cu, Pd, and Ag nanoparticles at chemically inactive electrified surfaces (glassy carbon and graphite). (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3231689] All rights reserved.