The Friedel-Crafts benzoylation of anisole with benzoic anhydride to yield 4-methoxybenzophenone has been performed in a range of ionic liquids, using homogeneous metal triflate catalysts. Of these, indium, scandium, and aluminum triflate were chosen to develop a kinetic model. A complex exchange of ligands between the metal salt, the benzoic anhydride, and the ionic liquids results in the formation of a free acid catalyst. This acid is shown to reversibly deactivated by complexation with the product; the equilibrium constant for this has been measured, and a rate equation has been developed and successfully tested.