Oleic and nitro-oleic acid behavior at an electrified water-1,2-dichloroethane interface

Abstract

In this work, oleic and 9/10-nitro oleic acid were studied at a polarized water-1,2-dichloroethane interface. We found that both fatty acids can undergo a simple interfacial ion transfer reaction that is mainly limited by diffusion. The possibility of spontaneous partitioning of the fatty acid into the organic phase and acting as a ligand for the facilitated sodium ion transfer was excluded. The ionic currents originating from the chemical species interfacial transfer were recorded starting from a pH of around 8.5, which agreed with their poor acidity. The acid-base properties of fatty acids were studied with pKa 9.7 (for oleic acid) and 8.5 for the 9/10-nitro derivative. The formal Galvani potential difference of the fatty acids ion transfer reaction was used to calculate the water-1,2-dichloroethane partition coefficients. The results indicated similar water solubility for 9/10-nitro oleic acid (logP' −3.47) and oleic acid (logP' −3.42), where 9/10-nitro oleic acid is slightly more hydrophilic. The partial water solubility of the fatty acids was confirmed by the measurement of ionic currents, which did not increase linearly with their increasing aqueous phase concentration. The obtained results were correlated with the dynamic light scattering of the fatty acids, indicating the formation of supramolecular structures. 9/10-Nitro oleic acid is an endogenously produced signaling molecule involved in cell redox homeostasis. The results obtained here could contribute to further (bio)chemical studies on fatty acid nitroalkenes.