ACTIVATION OF CLAYZIC AND ITS EFFECT ON THE RELATIVE RATES OF BENZYLATION OF AROMATIC SUBSTRATES

The effects of the activation of K10 montmorillonite supported zinc ch loride ('Clayzic') by different methods on the reactivity of the catal yst in the Friedel-Crafts benzylation of benzene and halobenzenes have been investigated. There is an optimum temperature for thermal activa tion in air at which point a rate enhancement, compared to unactivated Clayzic, in the benzylation of benzene of greater than 30 has been ac hieved. The rate limiting factor for these reactions is believed to be the ability of the aromatic substrate to enter the polar mesopores co ntaining the active zinc ions in Clayzic, causing unexpected and activ ation-dependent rate trends to be observed. Activation of Clayzic is b elieved to reduce the polar nature of the pores, so aiding partitionin g of the substrate into the catalyst.