| Abstract: | Unimolecular 1,2-methyl shift reaction and disproportionation of para-xylene is investigated by means of ab initio quantum chemical calculations. Isolated gas-phase models are used to estimate the optimum volume of the reaction complex. Space filling of the computed models is examined in zeolite Y, Beta and ZSM-5. It is suggested that the shape selectivity effect of zeolite molecular sieves on the disporportionation reaction can be associated with the steric conditions of the intrinsic rearrangement of the reaction complex in the course of the chemical transformation. |
