Oxidizing agents relative abilities

Construct Frost-Ebsworth diagrams for Ga, In and T1 at pH = 0. Use the diagrams to comment on (a) the relative abilities of Ga +, In + and Tl to act as oxidizing agents under these conditions, and (b) the relative stabilities of the +1 oxidation state of each element. 

The left column of each pair also shows the relative abilities of these metals to displace other metals from compounds. Zinc, for example, is above copper, so zinc is a more active reducing agent. It displaces copper ions from solutions of copper compounds, as shown in Figure 3.3. A copper(II) ion, however, is a more active oxidizing agent than a zinc ion. 

The ability of MPO to catalyze the nitration of tyrosine and tyrosyl residues in proteins has been shown in several studies [241-243]. However, nitrite is a relatively poor nitrating agent, as evident from kinetic studies. Burner et al. [244] measured the rate constants for Reactions (24) and (25) (Table 22.2) and found out that although the oxidation of nitrite by Compound I (Reaction (24)) is a relatively rapid process at physiological pH, the oxidation by Compound II is too slow. Nitrite is a poor substrate for MPO, at the same time, is an efficient inhibitor of its chlorination activity by reducing MPO to inactive Complex II [245]. However, the efficiency of MPO-catalyzing nitration sharply increases in the presence of free tyrosine. It has been suggested [245] that in this case the relatively slow Reaction (26) (k26 = 3.2 x 105 1 mol-1 s 1 [246]) is replaced by rapid reactions of Compounds I and II with tyrosine, which accompanied by the rapid recombination of tyrosyl and N02 radicals with a k2i equal to 3 x 1091 mol-1 s-1 [246]. 

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