Evaluation of boron doped diamond electrodes for organic electrosynthesis on a preparative scale⋆

Abstract

We have investigated some anodic and cathodic transformations using boron doped diamond (BDD) electrodes. The oxidation of a propargylic alcohol as well as the aromatic side chain oxidation in water as electrolyte did not yield the desired products in high yield and selectivity and led mainly to the formation of CO 2 due to electrochemical incineration of the starting material. With methanol as electrolyte, however, the reactivity of BDD electrodes is similar to graphite in most anodic methoxylation reactions, but the inactive behaviour of BDD electrodes leads to a different reaction pathway possibly involving methoxyl radicals with charge transfer from the electrolyte. It has been found that at BDD anodes benzylic single and double bonds can be split yielding aromatic acetals and esters. With phenanthrenes as starting material, o,o¢-disubstituted biaryls were obtained. So the use of BDD electrodes provides an efficient and environmentally friendly access to this interesting class of compounds. The high H 2 overpotential of BDD cathodes enables smooth and selective reduction of functional groups like oximes. Due to the high chemical and mechanical stability of the diamond layer of today's electrodes, electrode lifetime as well as reproducibility of the electrosyntheses has improved markedly. Aqueous basic conditions, however, must be avoided for BDD anodes. These conditions result in degradation of the diamond surface.

Application of BDD thin film electrode for electrochemical decomposition of heterogeneous aromatic compounds

“…The use of BDD thin film electrodes in anodic oxidation has shown that O 2 overvoltage is much higher than for conventional anodes, such as PbO 2 , producing larger amounts of quasi-free OH radicals and other oxidants (depending on supporting electrolytes). Oxidation of pollutants at these anodes produces CO 2 and H 2 O via a sequence of chemical reactions [10,11]. Another important advantage of the BDD electrodes is their stability under polarity inversion [12].…”

Metal Nanoparticle Modified Boron Doped Diamond Electrodes for Use in Electroanalysis

“…Now commercially available in a variety of forms and at varying levels of doping, the electrode is used in numerous areas of electrochemistry, ranging from analysis [13 -16], to synthesis [17,18], and catalysis [19,20], as well as having significant application to waste water treatment [21 -24], and uses in lithium batteries [25,26] and as superconductors [27 -29]. Electroanalysis at BDD electrodes specifically has over 250 publications to date, including unmodified, pretreated, metal-modified, polymer modified, nanocrystalline and arrayed BDD electrode systems.…”

Unexpected Highly Chemoselective Anodic ortho‐Coupling Reaction of2,4‐Dimethylphenol on Boron‐Doped Diamond Electrodes

“…[6] Furthermore, these particular electrodes were applied in the oxidation of propargylic alcohols and aromatic side chains. [7] Therefore, the anodic conversion of 1 on BDD electrodes was systematically studied. Electrolysis cells for conversions on BDD in aqueous media were developed by CSEM and described as Modular Electrochemical Cells for continuousflow applications.…”