Artículo de revista
A kinetic study of the reaction between boldine and singlet oxygen [O2(1Äg)]
Fecha
1997Autor
Zanocco Loyola, Antonio
Lemp Miranda, Else
Günther Sapunar, Germán
Institución
Resumen
The sensitized photo-oxidation of boldine and its permethylated derivative, glaucine, has been studied in
several solvents using steady-state kinetic methods. Values of kB, the total rate constant for the reaction
between boldine and O2(1Äg), vary from 3.44 × 107 M21 s21 in benzene to 150.00 × 107 M21 s21 in water. For
glaucine, similar values were determined. Quenching is faster in solvents with high capacity to stabilize a
charge or dipole (higher ð* parameter values). From these results, a charge-transfer quenching
mechanism, to account for the interaction between boldine and O2(1Dg), 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 ð* parameter. This last result can be explained in terms of a more polar
transition state leading to products.