Coupling of Phenol with Ketones in the Presence of Heteropoly Acids with Different Structures and Compositions

The reactions of phenol coupling with ketones MeCOR (R = CH3, C2H5, C3H7, and C4H9) are studied in the presence of heteropoly acids with different structures and compositions in toluene solutions ([PhOH]/[MeCOR] = (2–8)/1 mol/mol; 50–70°C) with thioglycolic acid added as a promoter. The reaction rate depends on ketone and heteropoly acid, and the yield of bisphenols is as high as 24–72%. The reaction orders are 0.68, 0.77, and 0.97 with respect to H6P2W21O71, H3PW12O40, and H4SiW12O40, respectively, and the activation energies are 25.1, 21.0, and 20.6 kcal/mol, respectively. Heteropoly acids of the Dawson structure exhibited the highest activity.