Synthesis of cis‐12, 13‐epoxy‐cis‐9‐octadecenol and 12(13)‐hydroxy‐cis‐9‐octadecenol from vernonia oil using lithium aluminum hydride

Abstract

Reduction of vernonia oil methyl esters (VOME) into epoxy fatty alcohol and diols was achieved with lithium aluminum hydride (LAH), under reflux and room temperature conditions, by using hexane and tetrahydrofuran (THF) as solvents . The reactions of VOME with LAH in hexane produced cis-12,13-epoxy-cis-9-octadecenol as a major product with an isolated yield of 73.62%, whereas the reactions with LAH in THF gave isomers of 12(13)-hydroxy-cis-9-octadecenol as the major products with an isolated yield of 95.1%. LAH was similarly reacted with vernonia oil (VO) to give the same products in lower yields. 1 H nuclear magnetic resonance (NMR), 13 C NMR, gas chromatography-mass spectrometry, and infrared were used to characterize these products.This study demonstrates the ability to control the reactivity of the epoxy functionality in VO or VOME with the choice of polar or nonpolar solvents, and extends the range of oleochemicals that can be derived from vernonia oil.The most extensively used oleochemicals, after fatty acids, are fatty alcohols, and there are growing efforts aimed at developing new derivatives and applications for the alcohols (1). Current laboratory methodology for their synthesis involves direct reduction of fatty esters with lithium aluminum hydride (LAH) (2). LAH is among the most powerful complex metal hydride reducing agents, with the ability to reduce carbonyl functionality in aldehydes, ketones, and esters to corresponding alcohols, while leaving the carbon-carbon double bond or carbon-carbon triple linkages untouched (3-5). In the case of the reaction of LAH with esters (2), the reduction of the ester functionality proceeds by nucleophilic attack of the hydride ion on the carbonyl group, leading to the formation of intermediate alkoxide salts from which the alcohol is generated upon acidification. Micovic and coworkers (6) reported on the production of corresponding alcohols resulting from the LAH reduction of tripalmitin and triolein, olive oil, lard, and oil of chaulmoogra glycerides. In another study, Walborsky and Colombini (7) reported on the syntheses of alcohol mixtures by the LAH reduction of glycidic esters. Ernest and coworkers (8,9) have also demonstrated the ability of LAH to reduce epoxides to alcohols.Therefore, we were interested in studying the reaction between LAH and vernonia oil (VO), which is a naturally epoxidized vegetable oil (10). The products from this reaction could constitute potential intermediates in the synthesis of oleochemicals from Vernonia galamensis seed oil, since it has been recognized as a potential oil seed crop (11,12). The initial interest was due to the unique fatty acid composition of its seed oil, which contains epoxidized triacylglycerols, of which trivernolin has been shown to be the major triacylglycerol (13,14).Previous work in our laboratory indicated that the epoxy functionality in VO was reactive toward nucleophilic reagents only under acidic conditions (12), whereas aminolysis (15) of the oil gave epoxy-containing amides with no indication of epo...

Chemically Functionalized Clay Vinyl Ester Nanocomposites II - Vernonia Oil-based Surfactant

“…The 1 H NMR spectrum of vernanol ( Figure 2) showed signals for the epoxy group corresponding to chemical shift of 2.9 ppm, the olefinic hydrogens at 5.4 ppm, the alcohol hydrogen at 1.6 ppm, and -methylene group at 3.6 ppm. These results are in agreement with published 1 H NMR data for purified vernanol [22]. The purified vernanol was then subjected to mesylation so that the introduction of mesylate group at the terminal position can assist in subsequent nucleophilic substitution of CN À group at the terminal end of this intermediate product.…”

Enzymatic synthesis of epoxy fatty acid starch ester in ionic liquid–organic solvent mixture from vernonia oil

“…However, the highly hydrophilic nature, and poor mechanical properties has hindered its wide application . Esterification is one of the common routes of modification of starch to attain desired properties . The main aims are to modify this biodegradable but crystalline and brittle material into new polymeric materials that are not soluble in water and have more tensile strength and enhanced functionalities.…”

Synthesis of Sodium (+)‐(12S,13R)‐Epoxy‐cis‐9‐octadecenyl Sulfonate from Vernonia Oil

“…Synthesis of the epoxidized alkenyl sulfonate 5 from VO required five reaction steps (Scheme 1) with an overall yield of 48%. Conversion of VO to VOME (1) was achieved with a base-catalyzed methanolysis (transesterification) of VO, a method previously published [3]. The yield of this reaction was 98% (crude product).…”

“…In previous work in our laboratory, we demonstrated the ability to control the lithium aluminum hydride (LAH) reduction of the epoxy functionality in VO or vernonia oil methyl esters (VOME) with the choice of polar or nonpolar solvents [3]. The use of polar solvents resulted in the formation of 12(13)-hydroxy-cis-9-octadecenol, while nonpolar solvent afforded (?…”