Possible origin of n-alkanes in high-wax crude oils

LONG-CHAIN n-alkanes, with a slight preference for odd carbon number, are major constituents of high-wax crude oils. It is generally believed that these n-alkanes form by defunctionalization of (loss of functional groups from)the major components of higher-plant cuticular waxes1. Recently however, another cuticular component - an insoluble, non-hydrolysable highly aliphatic bio-polymer2,3 - was proposed as a possible biological precursor of these n-alkanes3. Here we study n-alkane distributions in high-wax crude oils through a series of artificial maturation experiments performed on one such biopolymer, isolated from the leaf cuticle of the extant vascular plant Agave Americana L. At relatively low temperatures, the homologous series of n-alkanes generated exhibits an internal distribution pattern that is indistinguishable from that of n-alkanes in some naturally occurring high-wax crude oils. Similar types of resistant biopolymers present in algal cell walls might be a major source of n-alkanes in non-waxy crude oils.