An Improved Method for the Synthesis of Triarylmethanes Using Heterogenized 12-Tungestocobaltic Acid

Two heterogeneous catalysts based on 12-tungestocobaltic acid, including K5CoW12O40 and H5CoW12O40 supported on rice husk ash extracted nano silica (CoW/NSiO2), were used in selective alkylation of arenes with benzhydrol (diphenylmethanol). CoW/NSiO2 exhibited the highest activity. Thus, it was selected as the best choice for the synthesis of various triarylmethanes. This catalyst could be recycled by simple filtration and reused several times without any regeneration. Short reaction time, excellent yield and ease of catalyst recovery with consistent activity make this protocol efficient and environmentally benign.