TuP-14
OCCURRENCE AND STRUCTURE OF RING A DEGRADED TRITERPANE HYDROCARBONS IN SOME TERTIARY LACUSTRINE OIL SHALES
Christopher J. Boreham, Janet M. Hope and Zarko Roksandic
Australian Geological Survey Organisation, P.O. Box 378 Canberra ACT 2601, Australia
Alistair L. Wilkins
Chemistry Department, University of Waikato, Private Bag 3105, Hamilton, New Zealand
Ring-A degraded triterpanes in the Tertiary Messel and Duaringa oil shales were identified by mass spectrometry and tentatively assigned as des-A arborane, des-A oleanane and des-A lupane hydrocarbons. In one case, the structure of des-A 10alpha(H) arbor-9(11)-ene (Fig 1.) was elucidated using a combination of NMR, MS-MS, optical rotation and compound specific isotopic analysis. Another compound of the shales exhibiting identical MS and isotopic data was tentatively identified as the corresponding 10ß(H) isomer. Aromatic derivatives of arborane were also identified by mass spectra and comparison with literature data. Abundant des-A arborene in the Messel and Duaringa oil shales compared with minor des-A arborane suggests that formation of the saturated hydrocarbon is less favoured over aromatisation reactions.
