Abstract

The sensitized photo-oxidation of boldine and its permethylated derivative, glaucine, has been studied in several solvents using steady-state kinetic methods, Values of k(B), the total rate constant for the reaction between boldine and O-2((1) Delta(g)), vary from 3.44 x 10(7) M-1 s(-1) in benzene to 150.00 x 10(7) M-1 s(-1) in water, For glaucine, similar values were determined, Quenching Is faster in solvents with high capacity to stabilize a charge or dipole (higher pi* parameter values), From these results, a charge-transfer quenching mechanism, to account for the interaction between boldine and O-2((1) Delta(g),), is proposed, Rate constants for the chemical reaction are at least two orders of magnitude smaller than the total rate constants, which also show a large dependence on the pi* parameter. This last result can be explained in terms of a more polar transition state leading to products.