Triterpanes, pentacyclic

Hills, I. R., Whitehead, E. V., "Pentacyclic Triterpanes from Petroleum... 

The compounds detected in the mass range 398-454 in B3, BBl, BB2, and POW extracts appear to be pentacyclic triterpanes since all have prominent m/e 149, 177, 191, and 205 peaks (1 ). When selected ion profiles are compared, WYOl extract shows no m/e 191 peaks for GC retention times in the pentacyclic triterpane region. The BB coal extracts, B3, ALBl and POWl all have numerous small peaks that are probably triterpenoids. Some of these gave appreciable GC FID responses and good mass spectra. 

Several groups of hydrocarbon biological markers were identified in the coal extracts by mass spectrometry using selected ion scans. n-Alkanes, pristane, sesquiterpenes, several tricyclic alkanes and pentacyclic triterpanes with molecular weights from 398 to 454 were detected. 

Figure 15 shows isometric maps of Loveridge and Hiawatha coals and Noonan lignite. Shown on these maps are the mass chromatograms of m/e 191 and 206, and the molecular ions masses corresponding to the C27, C28, C29, C30, and C31 pentacyclic triterpanes. 

Normal and branched alkanes, benzene-alkylbenzenes, copaene, cadalene, phenols, sesquiterpanes, and pentacyclic triterpanes decrease in relative concentration with the maturity of the coal. 

Cyclic Alkanes. In the cyclic fraction the following polycyclic isoprenoid compounds were identified (4) 27 29 steranes> methyl-C2g sterane> C 7 32 Pentacyclic triterpanes of hopane type (except C ft), anathe bicyclic tetraterpane perhydro-8-caro-tane (Table IIJ. 

Four isomers of the triterpane suggested that in addition to the less stable 178H,218H hopane isomer, and more stable 17mass spectrum did not differ much from mass spectra of compounds of the hopane series. However, for a more reliable identification of these four triterpanes a more efficient GC separation plus authentic compounds for GC comparison would be necessary. 

Killops S.D., HowellVJ. (1991) Complex series of pentacyclic triterpanes in a lacustrine sourced oil from Korea Bay Basin. Chem. Geol. 91, 65—79. 

Other than rt-alkanes, pristane, phytane, and other isoprenoid alkanes that are present in abundance in unaltered oils and easily recognizable by GC and GC-MS analyses, most of the biomarker components are present in trace amounts. Among these, naphthenic hydrocarbons, including tricyclic terpanes, pentacyclic triterpanes, and steranes, have been studied most extensively because they carry more specific information on source and depositional environment than normal and isoprenoid alkanes [21]. 

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