Tocopherols as likely precursors of pristane in ancient sediments and crude oils

Abstract

Pristane and phytane, C14 and C20 isoprenoid alkanes respectively, are major components of many ancient sediments and crude oil. The phytyl side chain of the chlorophyll a molecule was believed to have been the natural source of these hydrocarbons, but the mechanism by which phytane and pristane are generated from the phytyl moiety of chlorophyll, under geological conditions, remain unclear. Here we suggest that tocopherols, also known as E vitamins, are likely sources of pristane found in ancient sediments and crude oils, as both flash pyrolysis and thermal degradation of α-tocopherol yield prist-1-ene as a major product. The organic moieties in the kerogens from which prist-1-ene is generated were previously shown to be similar to those yielding pristane under natural conditions1. As a consequence, pristane and phytane might very well originate from different precursors. © 1984 Nature Publishing Group.