A KINETIC-STUDY OF THE ANAEROBIC REACTIONS BETWEEN ADRENALINE AND IRON(III)

Iron(III) reacts reversibly in aqueous acid with adrenaline [epinephri ne, L-1-(3,4-dihydroxyphenyl)-2-(methylamino)ethanol, H2LH+] to give F eLH2+ and FeHLH3+. Both species decompose to yield iron(II) and the se miquinone, which in turn is oxidised further to the quinone. The latte r cyclises to form leucoadrenochrome, which is finally oxidised by iro n(III) to adrenochrome presumably via a semiquinone. The rate of appea rance and disappearance of the complexes, quinone, and adrenochrome co uld be followed by stopped-flow photometric methods. Mechanisms are pr oposed for the various steps, rate constants evaluated, and the revers ibility of the various redox steps discussed. These mechanisms are com pared and contrasted with those of the analogous reactions between iro n(III) and L-3-(3,4-dihydroxyphenyl)alanine.