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The use of high‐field carbon‐13 NMR spectroscopy to characterize chiral centers in isopranes
Author(s) -
Dalling Don K.,
Pugmire Ronald J.,
Grant David M.,
Hull William E.
Publication year - 1986
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260240303
Subject(s) - pristane , phytane , chemistry , squalane , diastereomer , hydrocarbon , chrysene , chemical shift , nuclear magnetic resonance spectroscopy , organic chemistry , carbon fibers , nmr spectra database , molecule , stereochemistry , spectral line , anthracene , materials science , physics , astronomy , composite number , composite material
The 13 C nuclear magnetic resonance spectra of four diastereomeric, acyclic isoprenoids [farnesane (C 15 ), pristane (C 19 ), phytane (C 20 ), and squalane (C 30 )] have been obtained as a means for interpreting hydrocarbon mixtures common in some fossil fuels and biosynthesized organic compounds. Multiple resonance environments were detected for carbons influenced by two or three chiral centers. Samples of farnesane and squalane were found to exhibit random stereochemistry, whereas the phytane sample was demonstrated to be a mixture of two isomers, probably the 6( R ), 10( S ), 14( R,S ) compound. The sample of pristane consisted of a single diastereomer and was probably obtained from a natural product. It is shown that general chemical shift assignments can be made in this class of molecules by considering the number of carbons located at positions one, two and three bonds distant, while assignment of closely spaced lines may be made on the basis of diastereomerically induced chemical shifts. Using these principles, the structural features of two fossil fuels were analysed.