Synthesis of δ‐stearolactone from oleic acid

Cermak, Steven C.; Isbell, Terry A.

doi:10.1007/s11746-000-0040-6

Cited by 27 publications

(19 citation statements)

References 13 publications

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“…Therefore, positional isomerization via deprotonation of adjacent hydrogens becomes the favorable path and results in an equilibrium between isomerized starting material and cation. The olefin then migrates back and forth along the chain as previously observed (16,21).…”

Section: Resultssupporting

confidence: 58%

“…This quantity of water is insufficient to liberate all of the ring-closed products from the glyceride. Sulfate esters most likely play an intermediate role in initial capture of the cation to form sulfonated fatty acids, which have been identified in other studies (21). The sulfonated fatty acids, upon neutralization, liberate hydroxy fatty acids that, under the reaction conditions, close to form δ-lactones.…”

Section: Resultsmentioning

confidence: 77%

“…Other olefin positions under lactonization conditions typically yield the γ-lactone as the predominant product (19,20). However, recent efforts (21) showed that a remote olefin can be isomerized and captured by the carboxylate to form the kinetic δ-lactone product in good yield (85%) and regioselectivity (δ/γ, 15.0:1.0).…”

mentioning

confidence: 99%

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Synthesis of δ‐eicosanolactone and δ‐docosanolactone directly from meadowfoam oil

Isbell

Cermak

2001

J Americ Oil Chem Soc

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δ-Eicosanolactone and δ-docosanolactone were synthesized directly from the triacylglycerides of meadowfoam (Limnanthes) oil. Perchloric and sulfuric acids were used in stoichiometric quantities (0.5-4.0 mol equiv) to cyclize triglyceride to δ-lactone. When the reactions were run in the absence of solvent at 40°C, δ-lactone yields ranged from 17-75% where δ/γ ratios ranged from 6:1 to 10.4:1. Sulfuric and perchloric acids gave similar yields for their individually optimized reactions. Perchloric acid-catalyzed reactions required less acid to produce similar amounts of δ-lactone (HClO 4 at 2.0 mol equiv gave 73% yield vs. H 2 SO 4 , which gave 75% yield at 2.5 mol equiv). The use of polar nonparticipating solvents during the reaction had little impact on δ-lactone formation or δ/γ ratio. Higher perchloric acid concentrations provided higher δ-lactone yields with δ/γ ratios remaining nearly constant. The effect of sulfuric acid on δ-lactone yield and δ/γ ratio was more direct; higher acid concentration improved both. Both crystallization and short path distillation improved δ-lactone quality, but short path distillation gave higher recovered yields. The δ-lactones were converted to their corresponding 5-hydroxy acids in the same reaction vessel, separated, and cyclized back to δ-lactones upon heating under vacuum. This provided a convenient method for δ-lactone purification.

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Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 77%

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Synthesis of δ‐eicosanolactone and δ‐docosanolactone directly from meadowfoam oil

Isbell

Cermak

2001

J Americ Oil Chem Soc

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“…The proposed mechanism involves formation of a carbocation that can undergo nucleophilic addition with or without carbocation migration along the length of the chain. If the migration continues to the C4 and C5 position, the fatty acid will cyclize to form lactones, the major side product to estolide formation (Scheme 2) (10)(11)(12)(13)(14)(15).…”

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confidence: 99%

Synthesis of estolides from oleic and saturated fatty acids

Cermak

Isbell

2001

J Americ Oil Chem Soc

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Oleic acid and various saturated fatty acids, butyric through stearic, were treated with 0.4 equivalents of perchloric acid at either 45 or 55°C to produce complex estolides. Yields varied between 45 and 65% after Kugelrohr distillation. The estolide number (EN), i.e., the average number of fatty acid units added to a base fatty acid, varied as a function of temperature and saturated fatty acid. The shorter-chain saturated fatty acids, i.e., butyric and hexanoic, provided material with higher degrees of oligomerization (EN = 3.31) than stearic acid (EN = 1.36). The individual, saturated fatty acid estolides each have very different characteristics, such as color and type of by-products. The higher-temperature reactions occurred at faster rates at the expense of yield, and lactones were the predominant side products. At 55°C, lactone yields increased, but the δ-γ-lactone ratio decreased; this led to lower estolide yields. The opposite trend was observed for the 45°C reaction. The saturate-capped, oleic estolides were then esterified with 2-ethylhexyl alcohol, and the chemical composition of these new estolides remained consistent throughout the course of the reaction.Paper no. J9799 in JAOCS 78, 557-565 (June 2001).Estolides are a class of esters, based on vegetable oils (1-4), that form when the carboxylic acid functionality of one fatty acid reacts at the site of unsaturation of another fatty acid to form an ester linkage. These linkages are used to help characterize the structure of the estolide since the estolide number (EN) is defined as the average number of fatty acids added to a base fatty acid (Scheme 1, EN = n + 1). The secondary ester linkages of the estolide are more resistant to hydrolysis than those of triglycerides, and the unique structure of the estolide results in materials that have far superior physical properties for certain applications than vegetable and mineral oils (5). Estolides have been found in nature (6,7) and have been synthesized (1-4,8) in the laboratory. Isbell and Kleiman (9) synthesized estolides from oleic fatty acids and found them to have interesting chemical behavior. The double bond in oleic acid is located at the 9 position which, under the correct conditions of acid concentration, reaction time, and temperature, undergoes estolide formation with minimal migration. The proposed mechanism involves formation of a carbocation that can undergo nucleophilic addition with or without carbocation migration along the length of the chain. If the migration continues to the C4 and C5 position, the fatty acid will cyclize to form lactones, the major side product to estolide formation (Scheme 2) (10-15).Lactones are formed from an intramolecular cyclization of a fatty acid carboxyl group with a carbocation located at the 4-or 5-position on a fatty acid backbone. Under the correct conditions, Showell et al. (13) and Cermak and Isbell (14,15) were able to produce γ-and δ-lactones, respectively. A major side product in the estolide synthesis, lactones are an interesting class of compounds...

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“…Pyrolysis at 650 • C of oleic acid in the same pyrolytic unit yielded fatty acids with shorter C chain (C 7 -C 16 ) and alkenes, aldehydes, alcohols, and ethers were also identified [56]. In addition, the lactones identified in the pyrolyzates of the melanins must have their origin in the major fatty acids C 16 and C 18 [57]. These lactones were even identified in the thermochemolysis with TMAH, either at 250 or 400 • C. This methylation procedure yielded non-methylated fatty acids and phenols (Table 4).…”

Section: Fatty Acidsmentioning

confidence: 99%

Analytical Pyrolysis of the Fungal Melanins from Ochroconis spp. Isolated from Lascaux Cave, France

et al. 2021

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Analytical pyrolysis is a tool widely used for investigating the nature of macromolecules. This technique has been applied with success for solving the chemical structure of geo- and biopolymers. However, with complex macromolecules, such as fungal melanins, analytical pyrolysis presents some drawbacks due to the fact that they rarely can be obtained in a pure grade and contains a mixture of polysaccharides, chitin, proteins, nucleic acids, and lipids, among other materials. Analytical pyrolysis permits the characterization of the compounds co-extracted or linked to the melanin. Nevertheless, our data revealed that under the conditions usually employed in the pyrolysis of melanins, the technique presented serious limitations due to the complex structure and diversity of components that suffer extensive thermal degradation through secondary reactions with the production of considerable number of artifacts. To the light of pyrolysis data, the melanin of Ochroconis spp. is not based on 3,4-dihydroxyphenylalanine (DOPA) or 1,8-dihydroxynaphthalene (DHN), and it is suggested that it could be a type of pyomelanin, based on the polymerization of homogentisic acid and other phenolic compounds.

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Synthesis of δ‐stearolactone from oleic acid

Cited by 27 publications

References 13 publications

Synthesis of δ‐eicosanolactone and δ‐docosanolactone directly from meadowfoam oil

Synthesis of δ‐eicosanolactone and δ‐docosanolactone directly from meadowfoam oil

Synthesis of estolides from oleic and saturated fatty acids

Analytical Pyrolysis of the Fungal Melanins from Ochroconis spp. Isolated from Lascaux Cave, France

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