Electrochemical Reduction of Benzhydrols
<p>The cathodic reduction of benzhydrols to diphenylmethanes in a 0.2 M tetraethylammonium tetrafluoroborate solution in acetonitrile were investigated. It was found that when the electrochemical reduction was conducted in a divided H-cell lined with conducting gel, the reaction afforded solely the desired product in fairly high yields but with fairly low efficiencies. The reductions were monitored through Gas Chromatography-Mass Spectrometry (GC/MS) analysis and the success of the reductions were confirmed with mass spectra, Proton Nuclear Magnetic Resonance (<sup>1</sup>H NMR) spectra, and Carbon Nuclear Magnetic Resonance (<sup>13</sup>C NMR) spectra. When the electrolysis solution was changed to acetonitrile-<em>d</em>, a mixture of mono-deuterated, protio, and sometimes di-deuterated alkanes were formed, with the mono-deuterated product being in the majority. The percent composition of the afforded product from the deuterated reductions was determined through <sup>13</sup>C NMR analysis without the Nuclear Overhauser Effect (NOE) to better visualize the splitting patterns and peak integrations. The formation of the different species formed in the deuterated reductions and the low efficiencies of the reductions suggest the presence of “back-reactions” that could be occurring in the electrolysis. The straightforward and neutral conversion of the electrochemical methods discussed here could be beneficial to the synthetic organic community as it could be utilized in the syntheses of larger molecules such as natural products and drug molecules.</p>