Effect of the acylating agent

The same effect is found for toluene acylation over BEA zeolite with derivatives of isobutyric acid isobutyric anhydride presents a higher initial activity compared with isobutyric chloride.[6] 

Consequently, adsorption phenomena of the acylating agent on the zeolitic catalyst plays a major role in determining the course of the reaction. 

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Under mild conditions (liquid phase, 160°C) HBEA zeolites can catalyse the acylation of phenol with phenyl acetate. High selectivity to p-hydroxyacetophenone is obtained by using sulfolane as a solvent, which can be explained by a better dissociation of phenyl acetate into acylium ions due to a solvation effect. However a competition between sulfolane and phenyl acetate for adsorption on the active acid sites is also demonstrated. A preliminary investigation of the effect of the acylating agent shows that generally, donor groups in aromatic acetates have a positive effect on the rate of acylation provided they do not block the access of the acetate to the acid sites of the zeolite pores. 

Table 3. Effect of the acylating agent chain length and activation on its reactivity ...

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