Highly active, reusable and moisture insensitive catalyst obtained from basic Ga-Mg-hydrotalcite anionic clay for Friedel-Crafts type benzylation andacylation reactions

Liquid phase benzylation (by benzyl chloride) and acylation (by benzoyl chl oride) of benzene and toluene over a Ga-Mg hydrotalcite (which is a basic a nionic clay) with or without HCl gas pretreatment and also over the hydrota lcite used earlier in the toluene benzylation (at 110 degreesC) have been i nvestigated. The fresh, used and HCl-gas-pretreated hydrotalcite catalysts were characterized for their surface area, basicity, crystalline structure and phases and also for their surface composition. The fresh hydrotalcite s howed no catalytic activity for both the benzylation and benzoylation react ions for a long period. However, after a long induction period (2.7 h), the catalyst showed a very high activity in the toluene benzylation (at 110 de greesC). Whereas, the catalyst after its use in the toluene benzylation or after its HCl gas pretreatment showed very high activity for both the react ions with a much shorter induction period. The hydrotalcite-derived catalys t consists essentially highly dispersed gallium and magnesium chlorides on MgO. The presence of moisture in the reaction mixture has beneficial effect s on the acylation reactions over the used catalyst.