The occurrence of pentacyclic triterpenes in the Green River shale

Urquhart, Brian Gilbert (1968) The occurrence of pentacyclic triterpenes in the Green River shale. MSc(R) thesis, University of Glasgow.

Abstract

This thesis investigates both the occurrence of pentacyclic triterpene hydrocarbons in the Green River shale and pertinent analytical topics. The introduction gives a concise summary of the scope, implications and limitations of organic geochemistry. The biogenesis, biological occurrence and known organic geochemistry, of triterpene hydrocarbons are also reviewed. The discussion describes the collection and characterisation of standard triterpene hydrocarbons necessary as an analytical aid, including an investigation into the use of osmylation as a method for detecting unsaturation in a triterpene. The development of a micro-sublimation block as a further assistance in the accurate characterisation of triterpenes is also described. The distribution of naturally occurring pentacyclic triterpenoids is presented both in tabular and text form in an attempt to clarify possible chemotaxonomic relationships of triterpene hydrocarbons isolated from geological environments. A description of the isolation, separation and fractionation procedures applied to the total lipid fraction of the Green River shale is followed by a discussion of the mass spectral cracking patterns of triterpenes. Several steranes/triterpanes and one tetraterpane were isolated from Fraction 1 (see flow diagram). Confirmation (based on mass spectral evidence) of the occurrence of cholestane, sitostane, ergostane, gammacerane and carotane can be made. In addition, another triterpane, tentatively identified as moretane, has been isolated. A series of hydrocarbons, postulated alkenyl benzenes, was isolated from Fraction 2. Such compounds have previously been found in petroleum, but have not been isolated from sediments. In addition, an unsaturated triterpene hydrocarbon, as yet unidentified, was also isolated from this fraction. The presence of this compound supports the hypothesis that saturated triterpenes present in sediments may be formed by reduction of the corresponding alkene, itself formed by dehydration of the biologically common oxygenated triterpenoids.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Additional Information: Adviser: Dr. G. Eglinton.
• Keywords: Organic chemistry, geochemistry.
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Supervisor, not known
• Date of Award: 1968
• Depositing User: Enlighten Team
• Unique ID: glathesis:1968-78515
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:13
• Last Modified: 13 Aug 2021 07:51
• Thesis DOI: 10.5525/gla.thesis.78515
• URI: https://theses.gla.ac.uk/id/eprint/78515