Cycloalkane Constituents of the Bitumen from Green River Shale.
Geochim Et Cosmochim Acta 1971 35:661-678
Fifty-two cyclic alkanes, isolated from the bitumen of Green River shale, were analyzed by mass spectrometry. The molecular formula of each cycloalkane was determined and, where possible, structural assignments were proposed for the alkanes on the basis of principal fragment ions and similarities in spectra to products of known configuration. Structural resemblance of these cycloalkanes to the hydrocarbon framework of biologically derived isoprenoid lipids was noted. Twenty-one cycloalkanes displayed fragmentation patterns similar to tetraalkyl substituted cyclohexanes. These compounds probably had their origin in carotenoid pigments. Six additional cyclic hydrocarbons produced mass spectra resembling the spectra of alkyl substituted hexahydroindanes. A progenitor of these compounds may be the indane portion of vitamin D, formed from the irradiation of steroidal plant debris. Mass spectra of eight other cycloalkanes suggest a structural similarity to alkyl substituted gonanes (steranes) and were probably derived form plant steroids. Fifteen of the cyclic alkanes (six tricyclic and eleven pentacyclic) produce mass spectra similar to the hydrocarbon skeletons of pentacyclic triterpenoids and could have been derived from them.
Geochim. Et Cosmochim. Acta, V. 35, 1971, PP. 661-678