Kinetic study of the reaction of leuco methylene blue with 2,6-dimethyl-p-benzoquinone in a reverse micellar system

The kinetics of the reaction of leuco methylene blue (MBH) with 2,6-dimethyl-p-benzoquinone (DMBQ) were studied in a heptane/bis(2-ethylhexyl)- sulfosuccinate (AOT)/water reverse micellar system. The pseudo-first-order rate constant (k _obsd) obtained in the presence of excess of DMBQ was found to be proportional to the initial concentration of DMBQ for W ₀=3, 5, 10, 15 and 20 (W ₀=[H₂O]/[AOT]). The second-order rate constant (k ₂=k _obsd/[DMBQ]₀) increased with an increase in the W ₀ value, but was almost independent of the concentration of the water pool. A mechanism involving the distribution of DMBQ between the reverse micellar interface and bulk organic solvent was proposed to explain these findings.