Photochemical cleavage of 1,2-diphenylethane-1,2-diol by water-soluble Fe III (tmpyp){Fe III (tmpyp)=[meso-tetrakis(1-methyl-4-pyridinio)porphyrinato]iron(III)}

Visible-light photolysis of 1,2-diphenylethane-1,2-diol and FeIII(tmpyp) in argon-saturated 50% aqueous MeCN afforded benzaldehyde and FeII(tmpyp) in a stoichiometric manner, and in the presence of air, benzaldehyde was photocatalytically produced with concomitant formation of benzoic acid as a minor product; turnover numbers and quantum yields strongly depended on the solution pH, virtually no reaction occurring at pH 2.