Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5162141 | Organic Geochemistry | 2015 | 12 Pages |
Abstract
Novel C34 and C35 hexacyclic hopanes having side chains with a pentacyclic or hexacyclic ring at C-22 are abundant in lacustrine oils and source rocks but almost absent from marine oils. The corresponding C34 and C35 hexacyclic hop-17(21)-enes were identified in thermally immature mudstones from Vietnam cored in the 500Â m deep ENRECA-3 well. All the novel hexacyclic compounds were unambiguously identified by comparison with synthetic standards. Traces of heptacyclic hopanes were detected in a lacustrine oil from Thailand. The C34 and C35 hexacyclic hopanes have much longer gas chromatography (GC) retention times than the corresponding pentacyclic hopanes. They are isomerized faster at C-22 than the pentacyclic hopanes and their 22S/(22SÂ +Â 22R) ratio values at equilibrium are much higher (0.8 for C34). Precursors could be penta- and hexafunctionalised hopanoids in cyanobacteria and methanotrophs.
Related Topics
Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Hans Peter Nytoft, Henrik Ingermann Petersen, Michael Bryld Wessel Fyhn, Lars Henrik Nielsen, Jussi Hovikoski, Ioannis Abatzis,