Document Abstract
The kinetics of the oxidation of paracetamol [PCM]
by water-soluble colloidal MnO2 was investigated spectrophotometrically
at 298 K in the absence and presence of an
anionic surfactant, sodium dodecyl sulphate (SDS), in aqueous
solution. The reaction was first order with respect to
[MnO2], [PCM] and [H2SO4]. The effects of [Mn(II)], [salt],
dielectric constant and ionic strength of the medium on the
kinetics of the reaction have also been examined. Micelles of
SDS in aqueous solution accelerated the reaction rate, and
partitioning of MnO2 in favour of the micellar pseudophase
was remarkable. The catalytic effect of SDS in aqueous solutions
has been treated by well-defined mathematical (Tuncay),
Menger and Portnoy, and Piszkiewicz models. The binding
constant (7.59 × 10−2 mol−1 dm3), dissociation constant
(32.43), rate constant in the micellar phase (5.15 × 104 s−1),
cooperativity index (1.98) and various thermodynamic activation
parameters have been evaluated, and on the basis of the
observed kinetic data, possible reaction mechanism and rate
law have been proposed.