Determination of enantiomeric purity of glycerides with a chiral PMR shift reagent

✍ Scribed by J. Bus; C.M. Lok; A. Groenewegen

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 518 KB
• Volume: 16
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(76)90004-9

✦ Synopsis

Tris(3-heptafluorobutyryl-d-camphorato)europium(Ill), Eu(hfbc) 3 was used to determine the optical purities of enantiomeric mixtures of tri-, di-and monoglycerides with various fatty acid chain lengths by proton magnetic resonance (PMR). Synthesized model enantiomers were used to assign PMR signals. Enantiomeric signal separation becomes more difficult if the chain length difference between the fatty acids in the 1-and 3-positions of glycerol becomes smaller. The sign of the enantiomeric shift difference (AA6) of the terminal acyl CH 3 group of 1-acyl-2,3-distearoyl-sn-glycerol vs its enantiometer remains the same in the series acyl is hexanoyl, butyryl, propionyl, but is reversed for acetyl.

The absolute configuration of the main triglyceride of the seed oil of Euonymus alatus was determined to be 3-acetyl-1,2-distearoyl-sn-glycerol and that of a monobutyryl triglyceride fraction from hydrogenated bovine butterfat was confirmed to be mainly 1,2-diacyl-3-butyryl-snglycerol. The enantiotopic behaviour of the glycerol CH 2 groups in (nearly) symmetric di-and triglycerides is discussed. * The enantiomeric (or optical) purity is defined as [S-enantiomer] -[R-enantiomer]/[S-enantiomer] + [R-enantiomer].