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United States Department of Agriculture

Agricultural Research Service

Title: Synthesis of Delta-Eicosanolactone and Delta-Docosanolactone Directly from Meadowfoam

Authors
item Isbell, Terry
item Cermak, Steven

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2001
Publication Date: N/A

Interpretive Summary: U.S. agriculture has been plagued by overproduction in recent years mainly due to large acreages of a select few crops. One method to reduce overproduction is to plant a new crop that will not provide the same raw materials when harvested. Meadowfoam is a new crop that can be grown as an alternative to traditional crops and provides a new raw material. This material was then chemically modified to a new compound called delta-lactone. delta-Lactone was made directly from the oil obtained from meadowfoam seed which provided a shorter and less expensive method than had been previously reported. The delta-lactone will be used to make dish soaps that are safer and won't harm the environment.

Technical Abstract: delta-Eicosanolactone and delta-docosanolactone were synthesized directly from the triacylglycerides of meadowfoam (limnanthes) oil. Perchloric and sulfuric acids were used in stoichiometric quantities (0.5-4.0 mole equivalents) to cyclize triglyceride to delta-lactone. When the reactions were run in the absence of solvent at 40 C, delta-lactone yields ranged from 17-75% where delta:gamma ratios ranged from 6:1 to 10.4:1. Sulfuric and perchloric acid gave similar yields for their individually optimized reactions. Perchloric acid catalyzed reactions required less acid to produce similar amounts of delta-lactone (HClO4 at 2.0 mole equiv. gave 73% yield versus H2SO4 which gave 75% yield at 2.5 mole equiv.). The use of polar non-participating solvents during the reaction had little impact on delta-lactone formation or delta:gamma ratio. Higher perchloric acid concentrations provided higher delta-lactone yields with delta:gamma ratios remaining nearly constant. The effect of sulfuric acid on delta-lactone yield and delta:gamma ratio was more directly related, where higher acid concentration improved both yield and delta:gamma ratio. Both crystallization and short path distillation improved delta-lactone quality but short path distillation gave higher recovered yields. The delta-lactones could be converted to their corresponding 5-hydroxy acids in the same reaction vessel, separated and cyclized back to delta-lactones upon heating under vacuum. This provided a convenient method for delta-lactone purification.

Last Modified: 12/22/2014
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