Method for producing phenolphthalein using heteropolyacid catalyst

A method for producing a phenolphthalein compound comprises: reacting a phenolic compound of the formula (I): wherein R1 is a hydrogen or a C1-C12 hydrocarbyl group, with a phthalic anhydride compound of the formula (II): wherein R2 is a hydrogen, a C1-C12 hydrocarbyl group, or a halogen, in the presence of a heterogeneous catalyst and a promoter to form a reaction mixture comprising a phenolphthalein compound of the formula (III): wherein each R1 is independently a hydrogen or a C1-C12 hydrocarbyl group; and R2 is a hydrogen, a C1-C12 hydrocarbyl group, or a halogen; wherein the heterogeneous catalyst comprises, on a porous support, a calcination product of a heteropolyacid composition.