Chemistry:24-n-Propylcholestane
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| IUPAC name
(24Ξ)-24a2-Homo-5ξ-stigmastane
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| Systematic IUPAC name
(1R,3aS,3bR,5aΞ,9aS,9bS,11aR)-9a,11a-Dimethyl-1-[(2R,5Ξ)-5-(propan-2-yl)octan-2-yl]hexadecahydro-1H-cyclopenta[a]phenanthrene | |
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3D model (JSmol)
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PubChem CID
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| Properties | |
| C30H54 | |
| Molar mass | 414.762 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
24-n-Propylcholestane is a sterane biomarker molecule often found in marine source rocks.[1][2] It is a C30 molecule, meaning that it is composed of thirty carbon atoms, and is one of the leading ways to distinguish a marine source rock from a terrigenous sample. It is composed of three six-carbon rings and one five-carbon ring, with two methyl groups and one eleven carbon side chain. 24-n-Propylcholestane has a molar mass of 414.76 g/mol.
24-n-Propylcholestane is a sterane, which are derived from sterols after being buried in the sediment. Sterols turn into steranes by saturating the sterol's double bond and removing the alcohol group.[3] Steranes are fairly stable, and are often found in source rocks and crude oils.[3]
24-n-Propylcholestane is derived from 24-n-propylcholesterol, which is made in the modern ocean by Chrysophyte algae.[4] Because of its known modern creator, it is thought that traces of 24-n-propylcholestane in ancient sediments were likely produced by older algaes of the same order Chrysophyte.[1] The marine algae is consumed by marine invertebrates, and so 24-n-propylcholesterols are also found in invertebrates, despite not being produced by them.[1] Regardless of which organism is observed containing 24-n-propylcholesterols, the molecule originated from Chrysophyte algae.
The ratio of 24-n-propylcholestanes to 24-iso-propylcholestanes is used as an indicator for the presence of sponges.
Detection
In sediments, sterane biomarkers are found as a mixture of stereoisomers. It can be difficult to separate out a specific stereoisomer, as is necessary for the detection of solely 24-n-propylcholestane. Because of this, 24-n-propylcholestane can be fairly difficult to detect using gas chromatography-mass spectrum (GC-MS). It has a m/z of 414 and a secondary peak at 217, and can be easily confused for a different group of C30 molecules, 4ɑ-methylsteranes.[1]
References
- ↑ 1.0 1.1 1.2 1.3 Peters, K. E.; Walters, C. C.; Moldowan, J. M. (2007). The Biomarker Guide: Volume 2, Biomarkers and Isotopes in Petroleum Systems and Earth History. Cambridge University Press. p. 527. ISBN 978-1-107-07962-5.
- ↑ Moldowan, J. Michael; Fago, Frederick J.; Lee, Cathy Y.; Jacobson, Stephen R.; Watt, David S.; Slougui, Nacer-Eddine; Jeganathan, Alwarsamy; Young, Donald C. (19 January 1990). "Sedimentary 12- n -Propylcholestanes, Molecular Fossils Diagnostic of Marine Algae". Science 247 (4940): 309–312. doi:10.1126/science.247.4940.309. PMID 17735849. Bibcode: 1990Sci...247..309M.
- ↑ 3.0 3.1 Dembicki, Jr., Harry (2017). "Interpreting Crude Oil and Natural Gas Data". Practical Petroleum Geochemistry for Exploration and Production. pp. 135–188. doi:10.1016/B978-0-12-803350-0.00004-0. ISBN 978-0-12-803350-0. "A classic example of a biomarker and its relationship to the biological precursor is cholestane and cholesterol"
- ↑ Moldowan, J. M.; Fago, F. J.; Lee, C. Y.; Jacobson, S. R.; Watt, D. S.; Slougui, N. E.; Jeganathan, A.; Young, D. C. (19 January 1990). "Sedimentary 12-n-Propylcholestanes, Molecular Fossils Diagnostic of Marine Algae". Science 247 (4940): 309–312. doi:10.1126/science.247.4940.309. Gale A8352545. PMID 17735849. Bibcode: 1990Sci...247..309M.
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