Os(VIII) accelerated oxidation of L-leucine by hexacyanoferrate(III) in CTAB micellar medium

The kinetics of Os(VIII) accelerated L-Leucine (L-Leu) oxidation in cetyltrimethylammonium bromide (CTAB) by hexacyanoferrate(III) [HCF(III)] was investigated by registering the decline in absorbance at 431 nm. Employing the pseudo-first-order condition, the reaction's advancement has been examined as an indicator of [CTAB], [Os(VIII)], [OH-], [L-Leu], [HCF(III)], temperature, and ionic strength. The results show that [OH-], [CTAB], and [L-Leu] are the critical parameters with a discernible influence on reaction rate. L-Leu interacts with HCF(III) in a 1:2 ratio. The rate constant is independent of the [HCF(III)] and is merely used up to regenerate the Os(VIII) during the reaction. In the investigated concentration ranges of Os(VIII), [OH-], and [L-Leu], the reaction demonstrates first-order kinetics, but follows less than unit order at higher concentrations of L-Leu (more than 6.0 x 10(-3 )mole dm(-3)) and alkali (more than 0.4 mole dm(-3)). A positive salt effect is indicated by the linear rise in reaction rate with additional electrolytes. CTAB catalyzes the process substantially, and once at its peak at 7.0 x 10(-4 )mole dm(-3), the rate remains constant as [CTAB] grows up to 8.5 x 10(-4 )mole dm(-3). With anionic surfactant sodium dodecyl sulfate, the reaction rate was significantly reduced even in the presence of Os(VIII). Reduced repulsion between surfactant molecule's positive charge heads brought on by the negative-charged HCF(III), OH-, and [OsO5(OH)](3-) molecules may be responsible for the witnessed drop in CTAB critical micellar concentration (CMC). [GRAPHICS] .