The rates of the ferricyanide oxidation of a number of isoquinolinium cations have been investigated in the range pH 11-14 in 20% CHSCN-80% H20 at 25 OC (ionic strength 1.0). The oxidation of the 2-methylisoquinolinium cation is kinetically first order in each of ferricyanide ion and isoquinolinium cation but is subject to pronounced inhibition by the ferrocyanide ion reaction product. Second-order rate constants evaluated from initial ...