Molecular graphics and structural fitting of aromatics in large-pore zeolites.

We describe the usefulness of molecular graphics and structural fitting techniques as powerful and reliable tools for quick screening of zeolite catalysts for shape selectivity. The syntheses of 4,4'-diisopropylbiphenyl and p-isobutylethylbenzene are considered as case studies. Molecular graphics analysis of the isomers of diisopropylbiphenyl and isobutylethylbenzene in various zeolites indicates that large-pore zeolites are needed for the synthesis of these alkylaromatics. The importance of size and shape of the channels of large-pore zeolites is clearly brought out by the structural fitting technique. From the analysis of the results of molecular graphics studies and the structural fitting studies, it is inferred that ZSM-12 and mordenite are suitable zeolites for shape-selective production of diisopropylbiphenyl, and that offretite and mordenite are suitable zeolites for shape-selective production of p-isobutylethylbenzene.