engleski

Kinetics of the oxidation of hydroxyurea with vanadium(V) ions in acidic aqueous solution

Hydroxyurea (HU) effectively reduces vanadate (VO2 +) into vanadyl (VO2+) species in acidic aqueous solution acting as a two-electron donor. The reaction starts by the formation of a transient complex followed by an electron transfer process that includes the formation and subsequent fading out of a free radical, U• (U•≡H2N–C(=O)N(H)O•). The rate determining step of the redox reaction is the formation of a free radical either by the inner-sphere one-electron transfer within the formed VO2 +-complexes, or by an outer sphere one- electron transfer from VO2 +-complex to the second VO2 + ion. Assuming a rapid pre-equilibrium for the proton-transfer and complexation reactions, an inner-sphere electron transfer pathway has been proposed when HU is in excess. When VO2 + in excess, an additional reaction possibly proceeds through two outer-sphere electron-transfer pathways

vanadate; hydroxyurea; redox; kinetics

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