The reactions of 1,2‐dioctylcyclopropene with silver nitrate

Kircher, Henry W.

doi:10.1007/bf02632441

Cited by 23 publications

(10 citation statements)

References 16 publications

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“…Separation of cyclopropenoic fatty acids by spinning band distillation requires relatively large proportions of starting material (16). AgNO 3 -chromatography is not suitable for the separation of cyclopropenoic fatty acids because of ring opening and other derivatization reactions catalyzed by silver ions (17,18). Methods used for the preparative isolation of cyclopropenoic fatty acids in good purity include repeated urea fractionations and crystallizations (9,19,20) as well as countercurrent distribution (19).…”

Section: Resultsmentioning

confidence: 99%

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

Fehling¹,

Schönwiese²,

Klein³

et al. 1998

J Americ Oil Chem Soc

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A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straightchain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C 18 reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95-97 and 95-98%, respectively. JAOCS 75, 1757-1760 (1998). KEY WORDS:Bombax munguba oil, cyclopropene fatty acids, malvalic acid methyl ester, preparative HPLC, Sterculia foetida oil, sterculic acid methyl ester, urea fractionation.Cyclopropene fatty acids are widely distributed in the seed oils of many plant families of the order Malvales (1,2). Small proportions of cyclopropene fatty acids, e.g., malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acids, which are present in crude cottonseed oil, are of special interest owing to their harmful biological effects when fed to animals (3-7).The presence of cyclopropene fatty acids in seed oils can be roughly checked by the Halphen test (8). Identification by gas chromatography (GC) and high-performance liquid chromatography (HPLC) analysis (9,10) is difficult, however, because no cyclopropene fatty acid standards are commercially available. This paper presents a simple method for the preparation of both methyl malvalate and methyl sterculate of high purity, which may be useful for GC and HPLC comparison as well as biochemical and enzymatic studies. The starting materials were seeds of Bombax munguba (11) and Sterculia foetida (1,2), which are known to be good sources of cyclopropene fatty acids. EXPERIMENTAL PROCEDURESMaterials. Distilled solvents were used throughout. HPLCgrade acetonitrile was purchased from Rathburn Chemicals (Walkerburn, Scotland). Silica gel, urea, and sodium methylate were products of E. Merck (Darmstadt, Germany). Bombax munguba Mart. seeds were collected at University of Paraiba, João Pessoa, Brazil (11); S. foetida L. seeds were a gift from Professor Helmut K. Mangold, Münster, Germany.Preparation of fatty acid methyl esters (FAME). Seeds of B. munguba (10 g) were ground in an electric coffee grinder and the meal extracted in a Soxhlet extractor for 6 h with 200 mL hexane. The hexane was evaporated and the oil transmethylated with sodium methylate in methanol (11). After addition of...

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Section: Resultsmentioning

confidence: 99%

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

Fehling¹,

Schönwiese²,

Klein³

et al. 1998

J Americ Oil Chem Soc

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“…Cyclopropane contents usually were calculated from the 9.8/~m absorption band in the IR spectra of samples which did not contain cyclopropenes or in which the cyclopropenes had been destroyed by treatment with methanolic silver nitrate (13). As an alternative, the methyl esters of the cyclopropane and other fatty acids were fractionated on a silver nitrate-silicic acid column (see below) and the saturated fraction containing the cyclopropanes was analyzed by GLC.…”

Section: Methods Of Analysismentioning

confidence: 99%

Hydrogenation of cyclopropenoid fatty acids occurring in cottonseed oil

Zarins

White

Willich

et al. 1982

J Americ Oil Chem Soc

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The hydrogenation of cyclopropenoid acids and their relative reactivities during hydrogenation as compared to linoleic and oleic acids were examined. Pure methyl sterculate and purified Sterculia foetida oil and its methyl esters, which have a cyclopropene content more than 60 times that of cottonseed oil, were used for the hydrogenation experiments. Nickel, palladium and platinum catalysts were used. The effect of temperature and type of catalyst Were demonstrated in a series of hydrogenation experiments of safflower and S. foetida oil mixtures, and methyl oleate and methyl dihydrosterculate mixtures. Partial hydrogenation of methyl sterculate formed as many as twenty compounds in addition to the cyclopropenoid derivatives. Most of these compounds were monounsaturated. The cyclopropene group hydrogenated very readily compared to the 9,12-diene system in linoleate. The cyclopropane group obtained by hydrogenating the cyclopropenoid acids group was quite resistant to further attack by hydrogen and nickel catalyst had little effect. With palladium catalyst, a temperature of 180 C was necessary for the reaction to go to completion. Platinum in acetic acid was a good system for hydrogenolysis of the cyclopropane group at 80 C.

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“…Direct gas-liquid chromatography of intact triacylglycerols containing CPFA moieties is not feasible because these substances undergo rapid thermal polymerization at high temperatures. The cyclopropene groups also react readily with silver nitrate to produce different derivatives depending on the organic solvent used in these reactions (Kircher, 1965;Johnson et al, 1967;Raju and Reiser, 1966).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, a method was developed (Schuch et al, 1986) for the analysis of triacylglycerols containing CPFA moieties; it involves the conversion of the cyclopropene group into stable ,/3-unsaturated keto derivatives. This method was based on the experiments conducted by Kircher (1965). We have adapted a similar methodology to analyze the triacylglycerols of Sterculia foetida seed lipids containing 72% cyclopropene fatty acids.…”

Section: Introductionmentioning

confidence: 99%