Phenol Coming and Going

Chemistry There are, broadly speaking, two ways to drive electric current. One is to separate the components of a chemical reaction so that the electrons travel separately from the ions; this is the working principle of a battery and yields direct current (dc). The other method is to rotate a wire loop through a magnetic field, which generates alternating current (ac). For the most part, when the process is inverted to drive chemistry via electricity, a dc approach is the most straightforward to implement, because it essentially runs a battery in reverse. However, ac-mediated chemistry can sometimes prove advantageous, as Lee et al. demonstrate in an exploratory small-scale electrolytic synthesis of phenol from benzene. The authors set up their cell so that benzene oxidation occurred at both the anode and the cathode, propelled in the former case by preliminary water oxidation and in the latter by oxygen reduction. Coupling vanadium oxide electrode catalysts with an indium-doped tin diphosphate solid electrolyte, they examined each half reaction in turn and found evidence for distinct mechanisms based on differences in temperature and potential dependences and Raman spectroscopic data. An alternating frequency of 30 Hz afforded optimal selectivity for the phenol product overall. Angew. Chem. Int. Ed. 51 , 10.1002/anie.201202159 (2012).