Cu^I/Ag^I‐containing coordination compounds as advanced catalysts for selective oxidation of styrene to benzaldehyde

Abstract

Four coordination compounds, [Cu(Hmthd)2Cl]n (1), [Cu3(mthd)2Br]n (2), [Ag(mthd)]n (3), and [Ag2(mthd)I]n (4) (Hmthd = 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole), were synthesized and characterized by inductively coupled plasma (ICP) elemental analyses, powder X‐ray diffraction (PXRD), and Fourier transform infrared (FT‐IR) spectroscopies. These resulting coordination compounds can act as efficient catalysts for the oxidation of olefins with tert‐butyl hydroperoxide (TBHP) as oxidant. Wherein, compound 2 performed extremely enhanced catalytic activity for oxidation of styrene at 80°C. Moreover, the addition of an appropriate amount of acid can promote the protonation of ligands and activate the two Ag‐containing catalysts to improve their catalytic efficiencies. Experimental results indicate that catalyst 2 has a low activation energy and excellent recycle catalytic property. Radical trap experiments were performed to verify that free radicals participate in the oxidation of styrene.