Influence of the Pore Diameter in Zeolites on the Activation Energy of Formation of 4-Alkyl-1,3-Dioxanes in the Prins Reaction

Abstract

Using the dependence of the activation energy of 4-alkyl-1,3-dioxane formation on the pore diameter of zeolites, the catalytic activity of the latter in the Prins reaction was theoretically explained. The stabilization of a prereaction π-complex in the cavities of a number of zeolites (${\text{Na}}_{x}^{ + }$(H₂O)_y)[Al_aSi_bO_c], Al_aP_bO_c, and Ca_x[H₂O]_yAl_aSi_bO_c) is studied by molecular dynamics methods. It is shown that the dependence of the stabilization energy of the π-complex and the transition state on the diameter of the cavity has an extremal shape. Taking into account the stabilization energies of the π-complex and the transition state in the zeolite cavity, the change in the activation energy of the 4-alkyl-1,3-dioxane formation is determined depending on the pore size. A comparison is made of the nature of changes in the transition state stabilization energy and the activation energy of the cavity diameter. It is demonstrated that the dependence of the activation energy on the diameter gives a narrower interval of optimal pore sizes.