Simulated degradation of glyceryl ethers by hydrous and flash pyrolysis

Hydrous and flash pyrolysis were carried out on phytanyl ethers isolated from a methanogen (Methanosarcina barkeri), a haloalkaphile (Haloalkaphile sp.) and a thermoacidophile (Sulfolobus sulfotaricus). No thermal alteration products of the intact ether lipids were observed below 150°C. From 150–300°C, slight pyrolysis of the intact glyceryl ethers was observed, although recovery of the parent compounds averaged >95%. As pyrolysis temperature increased, the alcohol and aldehyde were the first products formed following direct cleavage of the ether bond. At 600°C, the corresponding alkene also became a dominant flash pyrolysis product. With increases in pyrolysis temperature to 900°C, increasing amounts of volatile alkenes were produced. Based on the observed fragmentation patterns, we suggest that phytanol is first cleaved from the intact glyceryl ethers, followed by degradation of the phytanol to the corresponding alkanes or shorter chain components. In addition, as shown by other investigators, the alteration products may also be directly incorporated into higher molecular weight fractions.