The low temperature oxidation of Athabasca oil sand asphaltene observed from C-13, F-19, and pulsed field gradient spin-echo proton n.m.r. spectra

Carbon-13 and fluorine-19 nuclear magnetic resonance spectra of chemically derivatized, by phase transfer methylation and trifluoroacetylation, Athaba sca oil sand asphaltene, reveal a broad site distribution of different type s of hydroxyl-containing functional groups, viz., carboxylic acids, phenols , and alcohols. The low temperature air oxidation of asphaltene, at ca. 130 degrees C for 3 days, generates a few additional carboxyl and phenolic gro ups. These results are consistent with a mechanism in which diaryl methylen e and ether moieties react with oxygen. Self-diffusion coefficients, from t he pulsed field gradient spin-echo proton magnetic resonance technique, sug gest that low temperature oxidation does not appreciably alter the average particle size and diffusion properties of asphaltene in deuterochloroform. (C) 1998 Elsevier Science Ltd. All rights reserved.