Optimizing homologous alcohol oxidation: elucidating the impact of surfactant-alcohol hydrophobic interaction and micellar surface charge

Abstract

Micelles, a unique structural arrangement, function as nano-dimensional vessels in organic reactions, facilitating numerous catalytic transformations in water. This comprehensive study aims to explore the potential impact of two anionic surfactants (sodium dodecylsulphate or SDS or SC₁₂S and sodium tetradecylsulphate or STS or SC₁₄S) having dissimilar alkyl chain lengths and the hydrophobicity of the aliphatic alcohols (propanol and pentanol) as well on the overall kinetic profile of the oxidation study. The SDS micellar medium significantly encourages the reaction rate compared to STS micellar media. In the case of aliphatic alcohols with varying hydrophobicity, the same kind of rate is observed as with surfactants: (k_obs)_SDS-Propanol ~ 13-folds > (k_obs)_SDS-Pentanol ~ 11-folds > (k_obs)_STS-Propanol ~ 2.4-folds > (k_obs)_STS-Pentanol ~ 2-folds. The rate of the reaction improves as the aliphatic alcohol and surfactant hydrophobicity reduces. Herein, the effectiveness of micellar catalysis is greatly influenced by the surface charge of the micelle and surfactant-alcohol hydrophobic interaction. The kinetic observations are elucidated with conductometry, fluorometry, UV–Vis spectroscopy, FT-IR, ¹H-NMR, DLS, FESEM, TEM, and Zeta potential analysis. The Piszkiewicz’s kinetic model has also been applied to enlighten the linear rate acceleration in both micellar media.