Organic Reactions under Diffusion Control at Electrodes

Organic Reactions under Diffusion Control at Electrodes 

With most organic substances, particularly those of limited solubility in electrochemically useful solvents (e.g., water, alcohols, acetone-water mixtures, acetonitrile, propylene carbonate, formamide, dimethyl formamide. 

Diffusion-Limited Eiectrode Processes at Soiid Metais 

While diffusion-controlled conditions are deliberately introduced when organic electrochemical reactions are to be studied by means of polarography (see Section 8) at the Hg electrode, the situation often arises in practice that diffusion control becomes operative at solid electrodes, e.g., for fast reactions or toward the end of a preparative organic electrolysis. 

At solid electrodes, conditions of planar diffusion normally operate in distinction to the situation at growing spherical drops in polarography (see below), where spherical diffusion conditions obtain with the mass transport occurring along radial directions toward (or away from) the center of the drop. Planar diffusion occurs, however, at most solid electrode interfaces unless the surface exhibits roughness or crystallinity giving rise to local asperities and depressions of dimensionst comparable with those of the diffusion layer (viz., 0.05-0.01 cm) then the diffusion conditions are more complex. 

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