Catalytic steps occurred at liquid-solid interfaces are modulated not only by the interactions of reacting species, including the transition states, with the active sites and confines, but also by the surrounded solvent molecules. For the case of uni-molecular C-O scission, catalyzed by protons on Amberlyst-15, the effective rate constants (338 K) measured on largely unoccupied proton sites, vary by less than an order of magnitude across five different reactants of cyclohexanol, cyclopentanol, dimethyl-2-butanol, 1-phenylethanol, and trioxane at vapor-solid interfaces. Incorporating solvent molecules on these reactions markedly alters these rate constants, causing their values to increase or decrease, without a clear trend, spanning across six orders of magnitude. Here, we introduce a model with two parameters, combining with the use of a proxy molecule to interrogate the excess free energy properties, that would allow an accurate prediction of the solvent effects. The deviation of the rate constant values of the liquid-solid interface from that of the vapor-solid interface was quantitatively described here with the excess activation free energy term that was decomposed into two terms of (i) excess adsorption energy of the proxy molecule and (ii) Onsager function of the solvent, and two reactant specific parameters. The thermochemical construction provides the foundation on rationalizing the changes in the reactivity across the different solvents. It predicts the deviation of the activation free energies (338 K) across a wide array of solvents to an accuracy of < 4 kJ mol-1.
