Asphaltenes and resins from the Orinoco basin

Elemental analyses, molecular weights (by vapour pressure osmometry and gel permeation chromatography), 13C and 1H nuclear magnetic resonance precipitation and interfacial studies are reported for asphaltenes and resins from crude oils from the Orinoco basin. No major structural differences were found between coprecipitated resins and those remaining in the maltenes. The high number average molecular weights ( −M n) of asphaltenes (by v.p.o.) in benzene, 15000-7500, were reduced to ≈2000 after methylation or when measured in pyridine. The results from structural studies indicate the presence of a large number of aliphatic rings in the asphaltenes.