MANGANESE(III) OXIDATIONS OF BENZOYLHYDRAZINE, AROXYACETYLHYDRAZINE, SEMICARBAZIDE, THIOSEMICARBAZIDE AND THEIR DERIVATIVES IN PYROPHOSPHATE MEDIA

Manganese(III) ion was stabilised in weakly acidic solution by means o f pyrophosphate. Conditions for the quantitative oxidation of hydrazin e, benzoylhydrazines, aroxyacetylhydrazines, semicarbazide, semicarbaz ones, thiosemicarbazide and thiosemicarbazones were investigated by ti trimetric and potentiometric methods. The stoichiometries of these oxi dations were pH-dependent. At pH 5 benzoyl hydrazines were oxidised by donating two electron each, the nitro derivative being the sole excep tion to show a three-electron change. Aroxyacetylhydrazines, semicarba zide and semicarbazones underwent three-electron oxidations. The free radical nature of these reactions was illustrated. Thiosemicarbazides reacted faster than semicarbazides. Metal complexes of thiosemicarbazi de also yielded stoichiometric results, indicative of the number of TS C ligands in the complex. The oxidation products have been identified. At pH less-than-or-equal-to 1 these reactions conformed to different stoichiometries.