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The stereochemistry of bound and extractable pentacyclic triterpenoids during closed system pyrolysis

Lookup NU author(s): Mark Sugden, Dr Geoffrey AbbottORCiD

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Abstract

The distributions of hopanoic acids, ranging from C-30 to C-34, in the Messel oil shale were characterized in both the free and bound states. The bound acids were released by thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH). These were compared with the distributions of the hopanoic acids and hopanes released or generated from Messel oil shale kerogen following closed system microscale pyrolysis. This comparison revealed that epimerization had occurred at C-17, C-21 and C-22 during heating. It was also clear that the residual bound hopanoic acids had undergone configurational isomerization. During the pyrolysis there is a large loss of hopanoic acids following their rapid release from the kerogen into the free fraction even at 250 degreesC. In these particular experiments this loss does not appear to result in exclusive formation of hopanes, by way of decarboxylation or reduction reactions, unless the resulting hopanes are either themselves rapidly transformed into other compounds or the reaction rates are a function of the total number of carbon atoms in each hopanoic acid precursor. (C) 2002 Elsevier Science Ltd. All rights reserved.


Publication metadata

Author(s): Sugden MA, Abbott GD

Publication type: Article

Publication status: Published

Journal: Organic Geochemistry

Year: 2002

Volume: 33

Issue: 12

Pages: 1515-1521

ISSN (print): 0146-6380

ISSN (electronic): 1873-5290

URL: http://dx.doi.org/10.1016/S0146-6380(02)00114-6

DOI: 10.1016/S0146-6380(02)00114-6


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