No abstract

The alcoholysis reaction has been applied to the preparation of highly unsaturated alkyl esters from menhaden oil. This reaction proceeded very rapidly, and nearly quantitative yields were obtained with virtually no loss in double-bond structure. The formation of esters was studied, using straight-and branched-chain alcohols having 1-6 carbon atoms. The reactions were nmnitored by the technique of thin-layer chromatography ( T L C ) . Maximum conversion of straight-chain esters was found to be a linear function with respect to the number of carbon atoms in the alcohol. Reaction time varied from 2 min for methanol to 60 rain for n-hexanol. Branched-chain alcohols reacted more slowly than did the corresponding straight-chain compounds.This reaction was found to be applicable to laboratory and large scale preparations of highly unsaturated a]kyl esters.

A previously described procedure for the basecatalyzed alcoholysis of fish‐oil triglycerides with alcohols of low molecular weight has been applied to the preparation of alkyl esters using high molecular weight, aromatic, and terminally unsaturated alcohols. Some monoethers of ethylene‐and diethylene glycol have also been used in this work. Thin‐layer chromatography was used to follow the course of the reaction and determine optimum reaction times and yields of products.

The generally accepted methods for the synthesis of triglycerides are unsatisfactory when they are applied to highly unsaturated systems such as those present in fish oil. The methods either fail to g ive sufficiently high yields, or they are prohibitive in cost when applied to large scale production. Of the numerous reactions studied, the most feasible was the zinc‐catalyzed esterification of fish oil fatty acids with glycerol. Thinlayer chromatography (TLC) showed that this reaction gave yields of 75舑78% triglycerides. Gas‐liquid chromatography (GLC) demonstrated the composition of the triglycerides was essentially the same as that of the original fatty acids.