Model compounds for asphaltenes and C-80 isoprenoid tetraacids. Part I: Synthesis and interfacial activities

Three model compounds for asphaltenes and two model compounds for the C-80 isoprenoid tetraacids (ARN) have been synthesized and their interfacial and solubility properties were investigated. All compounds exhibit high interfacial activities. The asphaltene models lowered the interfacial tension between toluene and pH 9 to around 5mN/m at 12.5-35 mu M and the tetraacid models gave a drop in the interfacial tension between chloroform and pH 9 to 13mN/m at only 5 mu M, which is consistent with previous findings for the natural occurring C-80 tetraacids. A sudden drop in the IFT over a very narrow concentration range was observed for two of three asphaltene models. NIR spectroscopy studies indicated an aggregation most likely a result of polar and hydrogen bond interactions. The IFT results also showed different behavior with only small changes in chemical structure. The tetraacid models have similar interfacial behavior as the C-80 tetraacids and will thus be suitable model compounds with their highly UV active and fluorescent properties.