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The thermal degradation of 5α(H)-cholestane during closed-system pyrolysis

Lookup NU author(s): Dr Geoffrey AbbottORCiD, Dr Barry Bennett, Dr Stuart Petch

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Abstract

Involatile hydrocarbons were identified following the heating of 5 alpha(H)-cholestane in water with reaction vessel walls composed of 316 grade stainless steel and borosilicate glass. These analyses were compared with the hydrocarbon product compositions from closed-system pyrolysis experiments with no added water. Unsaturated hydrocarbons dominate their saturated counterparts following hydrous pyrolysis in both stainless steel-316 and borosilicate glass. In the absence of added water the converse is true in that saturated components dominate the hydrocarbon mixture. Backbone rearrangement in the steroid nucleus leading to spirosterene formation was only observed under aqueous conditions in both borosilicate glass and stainless steel-316 vessels. These comparisons demonstrate that water, as opposed to reaction vessel surface catalytic effects, plays a central role in mediating hydrocarbon degradation during closed-system hydrous pyrolysis. 5 alpha(H)-cholestane degradation under aqueous conditions is a complex composite of dissociative and rearrangement processes. These include (1) carbon-carbon bond cleavage in the sidechains as well as the ring system, (2) dehydrogenation, and (3) backbone rearrangement. These laboratory experiments provide a product description of the involatile hydrocarbons which will be the basis for a mechanistic study of 5 alpha(H)-cholestane degradation in hot water.


Publication metadata

Author(s): Abbott GD, Bennett B, Petch GS

Publication type: Article

Publication status: Published

Journal: Geochimica et Cosmochimica Acta

Year: 1995

Volume: 59

Issue: 11

Pages: 2259-2264

ISSN (print): 0016-7037

ISSN (electronic): 1872-9533

Publisher: Pergamon

URL: http://dx.doi.org/10.1016/0016-7037(95)00104-8

DOI: 10.1016/0016-7037(95)00104-8


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