Hexabenzocoronene Model Compounds for Asphaltene Fractions:  Synthesis & Characterization

Asphaltenes are the fraction of bitumen with the highest molecular weight, containing polyaromatic hydrocarbons rich in heteroatoms and polar groups that result in strong self-association under extraction and upgrading conditions. The synthesis of alkylated hexabenzocoronenes is here reported to provide new insight into the behavior of bitumen residue fractions. The self-association behavior of these polyaromatic model compounds is investigated over a range of temperatures using vapor pressure osmometry (VPO), nuclear magnetic resonance (NMR), optical and electron microscopy, X-ray and small-angle neutron scattering, and calorimetry (DSC/TGA). In addition to these experimental studies, computational studies are used to determine the contribution of alkyl−alkyl and π−π stacking interactions to this association behavior. Experimental and computational results are compared to asphaltene properties under extraction and upgrading conditions, as well as to the archipelago and pericondensed models proposed for asphaltenes.