Electrochemical Oxidation in Strong Acids

In the higher-acidity region, the intensity-potential curve shows two peaks (at 0.9 V and 1.7 V, respectively, versus the Ag/Ag+ system). The first peak corresponds to the oxidation of the protonated alkane and the second the oxidation of the alkane itself. 

The chemical equilibrium [Eq. (5.25)] is characterized by the constant Kx [Eq. (5.28)]. With the experimental conditions set to control p 2, the acidity level and R+ concentration, [RH] can be evaluated from voltammetric results and K can be determined. 

at a higher acidity level, another equilibrium must be taken into account, which is the protonation of the alkane [Eq. (5.28)] with constant K2 [Eq. (5.30)], and the oxidation reaction becomes pH-independent [Eq. (5.31)]. 

The acidity level at point A is representative of the basicity of the hydrocarbon If Ka is the acidity constant of the protonated alkane, thenpHA = pKA. On the other hand, as the redox reactions [Eqs. 5.26 and 5.27] are combined in Eq. 5.25, the equilibrium constant KL is related to the standard potentials of redox couples R+/RH and H+/H2 according to Eq. (5.32). 

Because K can be determined experimentally and the oxidation potential of H+/H2 is known in the acidity range, oxidation potential can be calculated. This allowed the 

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