The structural fitting and the interaction energy between the zeolite lattice models and organic molecules in the conversion of spirolactones to enones

We report here the results of our modeling studies and cluster calculations on the spirolactone to enone conversion reaction over zeolite catalysts. The structural role and the interaction energy introduced by the zeolite framework in this reaction are studied. The shape selective catalytic behavior of various zeolites are rationalized by comparing the dimension of the molecules and zeolite pore diameter. It is observed that the spirolactone and enone molecules have dynamic freedom to hop among the various sites inside the supercage of Zeolite-Y. The abstraction of proton at Bronsted acid site by ketonic oxygen of the reactant has been indicated as the first step in the reaction mechanism. The interaction energy of the molecules with the framework cluster and the electron redistribution occurring in the reactant molecules due to adsorption are brought out. These results are useful to understand the mechanism of the dehydration of spirolactones to form enones. (C) 1997 Elsevier Science B.V.