A Review of Macrocyclic Alkanes

Key words: 
• macrocyclic alkanes /
• NMR /
• MS fragmentation /
• biochemical synthesis pathway

Abstract: Macrocyclic alkanes are one kind of saturated fatty hydrocarbons which have single ring structure and large ring carbon numbers, which were identified in oil shales, petroleum, soils and higher plants. Because of the difference of macrocyclic alkanes characteristic carbon number with different sample, the equidistant relative retention time is same as long chain alkyl olefin and alkyl cyclohexane in chromatogram, the molecular ion (CnH2n) is same as olefin which have characteristic ion at m/z 97, 111, 125 in mass spectra and other compounds were similar, so it is easy to cause confusion and misunderstanding in actual identification. On account of this, we reviewed the identifications, the biosynthetic pathways and bio-precursors of macrocyclic alkanes. And confirmed the structure of those compounds by NMR analysis of purified monomer compounds in torbanite from Sydney Basin, Australia. Based on the fragmentation mechanism of cyclohexane doped out the fragmentation pathways of macrocyclic alkanes. Finally, according to the different research results provided by predecessors, the possible biochemical synthesis pathway of macrocyclic alkanes was summarized, which is helpful to better understand the parent material and bio-predecessor of macrocyclic alkanes, and better identify these compounds.