Liquid-solid reactions in a stirred reactor

Chemical kinetics deductions are, in some circumstances, possible from a reaction system using a dispersed solid. If the solid is entirely insoluble, for example a supported catalyst, true surface kinetics can be obtained provided (i) it can be shown that the chemical reaction on the surface is much slower than the associated mass transfer, and (ii) the surface area of the solid can be obtained. These conditions applied in the case of the oxidation of an aqueous solution of hydrazine using a dispersion of insoluble barium chromate [16]. Another case is where it can be shown that an increase in the amount of the solid component does not increase the reaction rate. In this case, exemplified by the formation of benzyl acetate from benzyl bromide and solid sodium acetate in toluene solvent, it is likely that the reaction occurs in the solution phase and that the reaction is proceeding at the saturation concentration of the solid reactant in the liquid phase [17]. 

In a study of the dissolution of potassium bicarbonate in dimethylformamide (DMF), Compton s group used ultrasound (25 kHz, 8 W cm 2) to provide mixing [18]. The rate was monitored via the homogeneous deprotonation of 2-cyanophenol by the dissolved potassium bicarbonate (Fig. 5.15), using spectroscopic and electrochemical techniques the 

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