|Kenar, James - Jim|
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2002
Publication Date: 2/20/2003
Citation: KENAR, J.A., WETZEL, A.R. PREPARATION OF FATTY 3,5-DISUBSTITUTED ISOXAZOLE COMPOUNDS FROM SOYBEAN FATTY ESTERS. JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY. 2003. v. 80. p. 711-716. Interpretive Summary: Currently, about 18 billion pounds of soybean oil are produced annually in the United States. Soybean oil is used primarily for food and feed purposes. Only a small amount (approximately 300 million pounds) is used industrially. The current social climate regarding environmental issues and pollution related to the use and waste disposal of non-renewable resources (petroleum based products) in industrial applications has clearly underscored the importance of utilizing renewable resources for industrial applications. The development of new approaches to utilize soybean oil to derive novel oleochemicals with unique chemical and physical properties is integral to extend the variety of compounds and uses obtainable from soybean oil. To meet these challenges, we have successfully introduced heterocycles (ring systems composed of nitrogen and oxygen atoms) onto soybean oil fatty esters. These new soybean oil derivatives may have application as bio-based corrosion inhibitors, and can also serve as versatile chemical intermediates that may be converted into other types of oleochemicals not currently available to the fats and oils industry. Finding new methods to effectively modify fatty acids and vegetable oils obtained from renewable resources and obtain bio-based industrial products not only benefits U. S. farmers, but also the environment. It will help to decrease our dependence on the ever tightening supply of non-renewable resources.
Technical Abstract: Fatty methyl esters derived from soybean oil (methyl palmitate, stearate, oleate, and linoleate) were converted into their corresponding long chain fatty isoxazole compounds in moderate to good yields (40%-64%) by condensing the ester moiety with the lithiated anion of N-(isopropylidene)isopropylamine followed by dehydrative cyclization. This approach allows readily available fatty esters to be utilized and incorporated into the construction of the isoxazole ring system. These novel products were isolated and characterized by nuclear magnetic resonance, infrared spectroscopy, gas chromatography-mass spectrometry, and melting point. Mass spectra of the fatty isoxazole compounds, derived utilizing electron impact ionization, showed distinctive cleavage patterns that occurred uniformly along the fatty alkyl chain allowing the position of double bonds to be readily located. Two prominent ions at m/z 97 and m/z 110 were common to all the fatty isoxazole compounds examined, and were presumably from a McLafferty rearrangement and a cyclization-displacement reaction, respectively. This represents a convenient method to utilize fatty esters to construct isoxazole fatty compounds not currently available to the fats and oils industry.