Unveiling the synergistic catalytic potential of sodium lauryl sulfate micelles and Ag(I): insights into the Mn(VII)-directed p-chlorobenzaldehyde oxidation kinetics
Abhishek Srivastava, Rajeev Kumar Dohare, Mrinmoy Goswami, Nitin Srivastava
Abstract
Abstract The influence of sodium lauryl sulfate (SLS) micelles on the Ag(I)-facilitated oxidation kinetics of p-chlorobenzaldehyde (PCBz) by KMnO4 has been investigated in the aqueous micellar media. The progression of the reaction is assessed by measuring the decrease in absorbance, employing the pseudo-first-order condition as an indicator for [H+], [Mn(VII)], [Na2SO4], [PCBz], [Ag(I)], and [SLS]. The examined reaction shows fractional first-order kinematics for [PCBz] and Ag(I), first order for [Mn(VII)], and fractional second order for [H+] across the examined concentration range. The kinetic outcomes have been scrutinized through various experimental methodologies, including conductometry, FT-IR spectroscopy, 1H NMR analysis, dynamic light scattering, and zeta potential measurements. The understanding of utilizing a combination of metal catalysts and surfactants in organic transformations arises from the focused pursuit of enhanced outcomes with reduced concentration of metal catalysts. The spectrophotometric kinetic investigation revealed that both Ag(I) and SLS catalyze oxidation independently, yet their combined influence is significantly more pronounced. The combination of Ag(I) and SLS micelles produces a 16.3-fold enhancement in the PCBz oxidation rate. The electrostatic attraction between the charged micelle and Mn(VII) promotes the proximity of the oxidizing species to the substrate (PCBz), which is typically solubilized in a micellar environment, thereby enhancing the oxidation process. A credible mechanism that corresponds with the kinetic findings has been emphasized, alongside an analysis of the Piszkiewicz model, to elucidate the apparent catalytic influence of SLS micellar environments.