Hydrocarbon composition of extracts obtained from petroleum fractions by extractive crystallization with thiourea

Structural Identification of Petroleum Acids by Conversion to Hydrocarbons and Multidimensional Gas Chromatography-Mass Spectrometry

“…The assignments are supported by the identification of multiple isomers of each acid type and are consistent with the (albeit sparse) previous evidence of such acids in other matrixes, identified as the esters . Where possible, the assignments were supported by close matches with the GC × GC retention positions and mass spectra of reference compounds and, for various isomers, the GC × GC elution order of the hydrocarbons additionally matched those reported for other complex mixtures, e.g., from catalytic conversion. ,− The retention indices of the peaks in Figure assigned as the structures in Chart are reported in Table S-2 in the Supporting Information.…”

“…This shows the complementary approach of analysis of both ester and alkane fractions by GC × GC-MS. In the alkanes, two later eluting peaks were also identified as both 2-ethylbicyclo[3.3.0]­octane isomers (Figure S-8A,C in the Supporting Information), the exo-isomer eluting before the endo-isomer, an observation made by Jørgensen et al as well as Bagrii et al for the 2-methyl isomers.…”

“…We were then able to confirm the corresponding acid methyl ester in the esterified NA by comparison of the mass spectrum with that of a reference compound ( 45 as well as Bagrii et al 46 for the 2-methyl isomers.…”

Petroleum Hydrocarbons

“…The publication of Lindeman and Tourneau (1963), which announced that norbornane and all four of its nearest methyl homo logs as well as bicyclo [3.3. 3.0]nonanes were separated and identified by thermal diffusion of a Californian crude, was a landmark in the study of relatively low boiling bicyclic naphthenes. This research gave an impetus to extensive studies in the chemistry of C 8 -C lO bicyclanes, which led to their discovery in crudes Bagrii et al 1967).…”