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The GLC and TLC resolution of diastereoisomeric polyhydroxystearates and assignment of configurations
Author(s) -
Wood Randall,
Bever E. L.,
Snyder Fred
Publication year - 1966
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02532543
Subject(s) - chemistry , diastereomer , silica gel , chromatography , resolution (logic) , thin layer chromatography , double bond , organic chemistry , artificial intelligence , computer science
Trifluoroacetate (TFA) derivatives of methyl 12‐hydroxystearate, methyl ricinoleate, five positional isomers of methyl threo ‐ and erythro ‐dihydroxystearate, four diastereoisomeric methyl 9,10–12‐trihydroxystearates, and four racemic diastereoisomeric methyl 9,10–12,13‐tetrahydroxystearates were prepared and analyzed by gas‐liquid chromatography (GLC). The isomeric threo ‐ and erythro ‐dihydroxystearates that had not previously been resolved by GLC were separated. Excellent resolution of the diastereoisomeric pairs of methyl threo ‐ and erythro ‐9,10–12‐triand and methyl erythro, erythro ‐ and threo, threo ‐9,10–12,13‐tetrahydroxystearates was obtained by GLC of their TFA derivatives. Analyses of these high‐molecular‐weight compounds were carried out on polar and nonpolar packed columns used routinely for methyl ester analysis. The various methyl mono‐, di‐, tri‐, and tetrahydroxysterate esters were also analyzed by thin‐layer chromatography (TLC) on Silica Gel G adsorbent layers and on Silica Gel G impregnated with sodium arsenite. Relative and absolute configurations were assigned to the various diastereoisomeric tri‐ and tetrahydroxysterates based on information obtained from GLC, TLC, synthetic ratios, and molecular‐models. A micro hydroxylation method that gives quantitative yields of threo ‐ and erythro ‐dihydroxy acids from various concentrations of C 18 monoene geometrical isomers was developed. Subsequent GLC analysis of the isomeric methyl dihydroxy TFA derivatives allows the quantitative determination of double‐bond configuration on small samples without expensive or specialized equipment.