Effect of Microwave Irradiation on Friedel-Crafts Diphenylmethylation of Arenes

The reaction between diphenylmethanols and substituted benzenes is useful to yield triarylmethane derivatives which are important skeletons in various functional materials and biologically relevant substances. The Reactions were carried out under microwave irradiation as environmentally-friendly method. In cyclohexane, the reaction was accelerated under microwave irradiation as compared to under conventional heating. Also, when more than 0.8 equivalents of iron(III) chloride were used, the acceleration was observed. Notably, when iron(III) chloride and arenes were combined, the temperature of the reaction solution rose to 40°C. It is considered that a chemical species was formed upon coordination of iron(III) chloride to the diphenylmethanols or arenes.