Pyrocatechol violet, oxidation

T. Deguchi, A. Higashi, and I. Sanemasa, Flow Injection Analysis of.Co-balt(II) by Catalytic Oxidations of Stilbazo and Pyrocatechol Violet. Bull. Chem. Soc. Jpn., 59 (1986) 295. 

Another spectrophotometric flow injection method for the determination of I- and based on the catalytic effect of this ion on the oxidation of pyrocatechol violet by potassium persulphate has been developed. The method allows the determination of 0.5-5 mg/11- at a rate of 60 samples per hour and is subject to very little interference. It was successfully applied to the determination of iodide in table salt (Cerda et al., 1993). 

An outer-sphere mechanism for the oxidation of pyrocatechol violet by C10 ion in HCl was suggested. The reaction is first order in both oxidant and substrate and follows acid-independent and acid-dependent paths via C10 and HC10 , respectively. The second-order rate constant decreases with increasing ionic strength. ... 

WOl inhibit the reaction. In contrast, however, WO promotes the decomposition of H2O2 alone. The oxidation of pyrocatechol violet in the presence of amino-acid complexes of copper(n) has been suggested as a means of determining ultramicroquantities of amino-acids e.g. in the presence of glycine the 1 1 complex acts as a catalyst, the pH-dependent reaction in borate buffer obeying the rate law (PV = pyrocatechol violet)... 

---