Investigation of hydrocarbon constituents of a young sub-bituminous coal by gas chromatography-mass spectrometry

Contrasted distributions of triterpene derivatives in the sediments of Lake Caçó reflect paleoenvironmental changes during the last 20,000 yrs in NE Brazil

“…Surprisingly, the fingerprints of aromatic derivatives in samples taken at 1.6 and 4.7 m depth globally resemble those described by Stout (1992) and Hazai et al (1986) for a lignite and a sub-bituminous coal, respectively. They comprise a series of monoaromatic pentacyclic compounds with various structures and degrees of unsaturation, a series of pentacyclic triaromatics and a series interpreted as diaromatic derivatives of tetracyclic triterpenes.…”

“…Compounds displaying resembling mass spectra have been reported in sub-bituminous coals (Hazai et al, 1986), in Tertiary angiospermous lignite (Stout, 1992) and were identified with synthetic standards (Wolff et al, 1989). According to spectral data and relative retention times, compounds 11, 12 and 13 could be dinor-oleana(ursa)-1,3,5(10),13 (18) ions at m/z 145, 157 and 172, the two additional double bonds cannot be both located on rings B or C since this latter configuration would lead to dominant m/z 221 fragment (Stout, 8 1992).…”

“…Their molecular weight of 378 amu is consistent with a C 28 H 42 formula. Comparable spectra have been described in Hazai et al (1986), Wolff et al (1989), ten Haven et al (1992 and Stout (1992) where they were attributed to ring A monoaromatic triterpenes with oleanane, ursane or lupane structures. Accordingly, we propose the structures of oleana(ursa)-1,3,5(10)-triene and dinor-lupa-1,3,5(10)-triene for compounds 15 and 22, respectively.…”

“…They are divided into three main groups with regard to their mass spectra, the most significant fragments of which are listed in Table (Laflamme and Hites, 1978;Wakeham et al, 1980;Chaffee et al, 1984;Hazai et al, 1986;Chaffe and Fookes, 1988;Loureiro and Cardoso, 1990;Stout, 1992). The relative intensities of ions m/z 145, 157, 158, 170 and 172 depend on whether additional unsaturations are located on rings B, C, D or E. As demonstrated by several authors (Lohmann, 1988;Loureiro and Cardoso, 7 1990), the double bond position in natural product precursors is often preserved in diagenetic derivatives.…”

“…To our knowledge, few reports of such mass spectra have been published (Hazai et al, 1986;Stout, 1992;Killops et al, 1995 andHauke, 1994). hydrogen atoms as compared with the compound with a molecular ion at m/z 374.…”