Synthesis and analysis of optically active triglycerides

Physical‐chemical methods for steric analysis of asymmetrical triglycerides and 1,3‐diglycerides have been investigated. Aliphatic triglycerides exhibit optical rotation at the D line and in the ultraviolet to 313 mƁ when they contain greatly different fatty acid substituents, such as isobutyric, sorbic or others contrasted with plamitic and similars. However, optical rotation is not demonstrable with triglyceride antipodes which have only palmitic, oleic and similar component acids. Since their optical rotation is not apparent, they are called cryptoactive glycerides. Presence or absence of the piezoelectric effect permits diagnosis of antipode or racemate with crystalline tri‐ and diglycerides. Mixed melting point diagrams of one antipode and/or of the racemate with the triglyceride of unknown configuration can be used to identify the latter. X‐ray diffraction patterns of antipode and racemic glycerides are different, and configuration assignment is possible by making comparisons. The optical rotation, ॅd = +0.19Ŷ, of dolphin oil was found to be due to S(+)‐methylethylacetic acid which occurs as a component acid in the triglycerides. The optical activity ofeuphorbiaceae triglycerides is discussed and some pertinent model compounds have been prepared. 2‐Oleo‐palmitostearin from fresh cocoa beans was found to be the racemic compound. Application of the Cahn‐Ingold‐Prelog R,S nomenclature to glycerides is outlined. Numerous glycerides have been synthesized in stereospecific form and their physical data are given. Some comments are made on stereospecific analysis of triglycerides without separating them.