CATALYTIC AND COMPUTER-SIMULATION STUDIES OF CARBON-SULFUR BOND-CLEAVAGE OVER ZEOLITE-Y

N-Substituted carbonimidodithioic acid dimethyl esters, when reacted w ith an active methylene compound such as nitromethane, undergo carbon- carbon bond formation followed by carbon-sulphur bond cleavage in the presence of zeolite catalysts to give 1-substituted amino-1-methylthio -2-nitroethanes. This carbon-sulphur bond cleavage is facilitated by t he presence of rare earth cations in the zeolite-Y framework. The shap e selectivity of the zeolite also plays an important role in this clea vage reaction. Force field calculations adopted for the molecules invo lved in the reaction indicate the geometry and conformational flexibil ity of these molecules. The computer-simulated model for the zeolite-Y is correlated with the conformation and shape of the reactant and pro duct molecules to explain the variation in yields obtained in the conv ersion of substituted dimethyl esters.