The impact of a solvent environment on persistent free radical concentrations at ambient conditions was studied by electron spin resonance spectrometry. The analyte selected was Canadian oil-sand-derived bitumen due to its high persistent free radical content. The ability of 54 different solvents to produce a homogeneous 5 wt % solution of bitumen was evaluated. The influence of solvents on the free radical content in bitumen was determined exclusively for solvents that were capable of quantitatively dissolving the bitumen. These were compounds in the classes of alkynes, mono-and bicyclic benzene-derivatives, and heteroatom-containing compounds containing nitrogen, oxygen, sulfur, and chlorine. It was found that a shift in the g-factor of bitumen occurred when the solvent was changed. The shift was attributed to the radical−solvent interaction that is affected by the polarity of the solvent and reflected in the solvent dipole moment property. The change in the free radical concentration was independent of changes in g-factor and was not correlated with any of the following solvent properties: molecular weight, dipole moment, dielectric constant, refractive index, density, and viscosity. There was a relationship between the free radical concentration in bitumen and the ionization potential of sulfur-containing and diaromatic hydrocarbon solvents. It was concluded that the bulk liquid properties that affected the electronic environment of the free radical species, resulting in a shift in g-factor, were not related to the bulk liquid properties that affected the dissociation equilibrium and resulted in a change in the free radical concentration.
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.