Renewable dissymmetric sulfonate gemini surfactants from addition of sodium hydrogensulfite to alkyl linoleate

A new series of bio-based sulfonate gemini surfactants was synthesized through esterification of renewable linoleic acid with various alcohols and subsequent sulfonation with readily available sodium hydrogensulfite (NaHSO3). Organocatalytic sulfonation of methyl linoleate with NaHSO3 by the triethylamine and tert-butyl peroxybenzoate catalyst system was investigated, where a methyl linoleate conversion of 96.4% could be achieved while generating high purity product without tedious purification. Three resulting sodium alkyl linoleate disulfonates (SALDs) have been characterized by Fourier transform infrared, high-performance liquid chromatography, LC–MS, high-resolution mass spectrometry (HR–MS), nuclear magnetic resonance techniques, and thermogravimetric analysis. The physicochemical properties and surface properties of the SALDs at various concentrations were investigated. The results showed that the SALDs exhibited low Krafft temperature, high water solubility, foam stability (foam half-life time could reach 15 min), emulsifying ability (emulsification time of 2.0 g/L is 192 s), and good thermal stability. This study enriches the family of anionic gemini surfactants and provides reference data for facile preparation of gemini surfactants.