Computer simulation study on the conversion of spirolactone to enones over H-Y zeolite

We report here the results of computer modeling studies and quantum chemical calculations on the spirolactone-to-enone conversion reaction over the zeolite catalysts, especially H-Y zeolite. We studied the adsorption mode of the molecules inside the supercage of H-Y and the mechanism of electron transfer between organic molecules and the framework of zeolite H-Y by density functional theory (DFT) calculations. Because the organic molecules considered in the present study are less symmetrical we docked the molecule inside the supercage of H-Y and energy minimization was then applied to these docked structures to yield representative low-energy binding sites for the molecules within the host structure. The interaction energy results show that the major interaction is between the methylene hydrogen of the molecule and the oxygen of the framework. The molecular electrostatic potential maps show that the ketonic oxygen of the reactant molecules abstract proton from Brönsted acid site. Thus the mechanism proposed by DFT calculation matches well with the experimental observations.