Phytane is the isoprenoid alkane formed when phytol, a chemical substituent of chlorophyll, loses its hydroxyl group.

Among them, crocetane is a tail-to-tail linked isoprenoid and often co-elutes with phytane during gas chromatography (GC) due to its structural similarity.

Phytanyl groups are frequently found in archaeal membrane lipids of methanogenic and halophilic archaea[4] (e.g., in archaeol).

[6] Hydrolysis of chlorophyll a, b, d, and f during diagenesis in marine sediments, or during invertebrate feeding[7] releases phytol, which is then converted to phytane or pristane.

Laboratory studies show that thermal maturation of methanogenic archaea generates pristane and phytane from diphytanyl glyceryl ethers (archaeols).

[13] However, various biotic and abiotic processes may control the diagenesis of chlorophyll and phytol, and the exact reactions are more complicated and not strictly-correlated to redox conditions.

[3][4] In thermally immature sediments, pristane and phytane has a configuration dominated by 6R,10S stereochemistry (equivalent to 6S, 10R), which is inherited from C-7 and C-11 in phytol.

Oils from rocks deposited under open-ocean conditions showed Pr/nC17< 0.5, while those from inland peat swamp had ratios greater than 1.

In contrast, biodegradation increases these ratios because aerobic bacteria generally attack linear alkanes before the isoprenoids.

For example, δ13C(PDB) of phytane in marine sediments and oils has been used to reconstruct ancient atmospheric CO2levels, which affects the carbon isotopic fractionation associated with photosynthesis, over the past 500 million years.

[22] Hydrogen isotope composition of phytol in marine phytoplankton and algae starts out as highly depleted, with δD (VSMOW) ranging from -360 to -280‰.

In another example, the decrease in Pr/Ph during deposition of the PermianKupferschiefer sequence in Germany is in coincidence with an increase in trimethylated 2-methyl-2-(4,8,12-trimethyltridecyl)chromans, an aromatic compound believed to be markers of salinity.