n. shabestary

A naturally occurring clay mineral, hectorite, was used as the support for quaternary ammonium cations. The intercalation of the cations by the clay has the advantage of separation of the catalyst from the product by a simple filtration technique. Several quaternary ammonium cation clay intercalates have been used to investigate the effects of alkyl chain length, size and shape of these catalysts in converting n-butyl bromide to n-butyl chloride. It appears that the hectorite intercalates have a great tendency for emulsification in the presence of organic solvent (toluene) and water. In fact, the emulsification being facilitated by the clay intercalates helps to bring the nucleophile from the aqueous phase into contact with the substrate, which is contained in the organic phase. The rate of the reaction was measured for the biphase reaction (no supporting clay) and for the triphase catalytic system (with supporting clay) for comparison. Relatively large differences in reactivity have been observed between the catalysts chosen in this research. The results have indicated that quaternary ammonium with certain carbon numbers has higher catalytic activity.