Analysis of Products from Reactions of Chemisorbed Monolayers at Smooth Platinum Electrodes: Electrochemical Hydrodesulfurization of Thiophenol Derivatives

Article abstract of DOI:10.1021/ac00127a015

The product mixtures from electrochemical hydrodesulfurization of selected thiophenolic compounds chemisorbed through the -SH moiety at smooth Pt electrodes in molar acid have been analyzed quantitatively by using thin-layer electrochemical methods in conjunction with capillary gas chromatography and liquid chromatography.The following compounds were studied: pentafluorothiophenol (PFT), mercaptohydroquinone (MHQ), and 2-mercaptobenzoic acid (MBA).A comparatively high area, large-volume preparative thin-layer electrode (TLE) was constructed to facilitate sample analysis.The results obtained from TLE, GC, and HPLC analysis were in good agreement.The extent of hydrodesulfurization (defined here as simple cleavage of the C-S bond without impairment of the aromatic functionality) depended on the nature of the pendant aromatic ring, decreasing in the order PFT (100percent) >> MHQ (50percent) >>MBA (15percent).Only one desulfurization product was observed for MHQ and MBA; the absence of other products was probably because ring hydrogenation (to form alkyl-type groups) competed with simple desulfurization, and detachment of the alkyl moieties from the -SH anchor occured with greater difficulty than that of the aromatic group.