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1.
G. van den Bosch 《Journal of the American Oil Chemists' Society》1973,50(12):487-493
Methyl oleate and linoleate were treated with 10% acid activated clay at 90–100 C for 1–50 hr with and without admission of
air. Positional and geometric isomers of fatty acid esters were found. Polar compounds were detected having one or more functional
groups with respect to the starting esters. Preparative thin layer chromatography and gas liquid chromatography were used
in isolating the compounds, while IR, NMR, mass spectroscopy, and gas liquid chromatography analysis were employed for identification.
The unsaturation of the isolated isomers was present at carbon atoms 5–11. The polar compounds were, among others, 9- and
10-keto octadecanoic methyl esters, isomeric keto octadecenoic methyl esters, isomeric epoxy octadecanoic methyl esters, 9-
and 10-hydroxy octadecanoic methyl esters, and some mono methyl ester dicarbonic acids. It may be concluded that geometric,
as well as positional, isomerization occurs and that small amounts of compounds with one or more functional groups are formed
when unsaturated fatty acids were treated with acid-activated clay. 相似文献
2.
The mixture of diene hydroperoxides from methylene blue-sensitized oxidation of methyl linoleate was reduced with NaBH4 and the resulting alcohols were separated by high pressure liquid chromatography (HPLC). Four diene alcohols were isolated
in approximately equal yields from adsorption and reversed phase HPLC; the isomers were identified as methyl esters of 9-hydroxy-10,12-,
10-hydroxy-8,12-, 12-hydroxy-9,13- and 13-hydroxy-9,11-octadecadienoate. Formation of equal yields of both conjugated and
nonconjugated diene alcohols from methyl linoleate is characteristic of singlet oxygen oxidations. The detection of the easily
separated nonconjugated isomer methyl 10-hydroxy-trans-8,cis-12-octadecadienoate from methyl linoleate is proposed as a test to probe the involvement of singlet oxygen in biological
oxidations.
A preliminary report of these results was presented at the 177th meeting of the American Chemical Society, Honolulu, HI, April
1–6, 1979; see abstracts of papers, paper No. ORGN-375. 相似文献
3.
The chemical synthesis of methyl 9-(2′-n-butylcyclopentyl)nonanoate and methyl 10-(2′-n-propylcyclopentyl)-decanoate was performed
using a Wittig reaction between 2-alkylcyclopentanones and the corresponding ω-carbomethoxyalkyl triphenylphosphonium bromides.
The intermediate alkylcyclopentylidene alkanoate esters were isolated from the reaction mixture, characterized by spectrometric
methods, and then catalytically hydrogenated to the desired cyclopentyl esters. Gas chromatographymass spectrometry (GC-MS)
showed that the final products contained a mixture oftrans- andcis-ring isomers with small amounts of other cyclic by-products. The GC-retention features, the mass fragmentation pattern, and
the spectroscopic characteristics of both the final and the unsaturated intermediate products are discussed. 相似文献
4.
E. W. Bell 《Journal of the American Oil Chemists' Society》1974,51(6):284-285
A procedure is described for the catalytic aromatization of the ethylene adduct of conjugated isomers of methyl octadecadieonate.
When the C20 cyclohexene fatty methyl esters were heated at 290–300 C with palladium and 1-octadecene as hydrogen acceptor, C20 aromatic cyclic esters were obtained in 90–95% yield. 相似文献
5.
E. Fehling S. Schönwiese E. Klein K. D. Mukherjee N. Weber 《Journal of the American Oil Chemists' Society》1998,75(12):1757-1760
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 straight-chain 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 C18 reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97
and 95–98%, respectively. 相似文献
6.
J. L. Sebedio J. L. LeQuere O. Morin J. M. Vatele A Grandgirard 《Journal of the American Oil Chemists' Society》1989,66(5):704-709
Fractions of cyclic fatty acid monomers (CFAM) were isolated from linseed oil heated at 275°C for 12 hr under nitrogen, at
240°C for 10 hr under nitrogen and at 240°C for 10 hr under air. Cyclic fatty acid monomers fractions were also isolated from
a sunflower oil heated at 275°C for 12 hr under nitrogen and at 200°C for 48 hr in a commercial fryer. The CFAM fractions
were hydrogenated and their composition studied by gas liquid chromatography coupled with mass spectrometry (GC-MS). The CFAM
in the fraction isolated from heated linseed oil samples were a mixture (1:1) ofcis andtrans cyclopentyl and cyclohexyl isomers, while the CFAM in the fractions isolated from heated sunflower oils were mostly cyclopentyl
isomers. The major cyclopentyl isomers weretrans andcis methyl 7-(2′-hexylcyclopentyl) -heptanoate, methyl 9-(2′-butyl-cyclopentyl)-nonanoate and methyl 10-(2′-propylcyclo-pentyl)-decanoate.
The major cyclohexyl isomers were thetrans andcis methyl 9-(2′-propylcyclohexyl)-nonanoate which represented about 50% of the CFAM isomers isolated from heated linseed oil
samples.
For part II in this series see Ref. 1. 相似文献
7.
α-Tocopherol was reacted with alkyl and alkylperoxyl radicals at 37°C in bulk phase. The lipid-free radicals were generated
by the reaction of methyl linoleate with the free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (AMVN) under air-insufficient conditions. The products were isolated by high-performance liquid
chromatography. Their structures were identified as 2-(α-tocopheroxy)-2,4-dimethylvaleronitrile (1), a mixture of methyl 9-(8a-peroxy-α-tocopherone)-10(E),12(Z)-octadecadienoate and methyl 13-(8a-peroxy-α-tocopherone)-9(Z),11(E)-octadecadienoate (2), methyl 9-(α-tocopheroxy)-10(E),12(Z)-octadecadienoate (3a), methyl 13-(α-tocopheroxy)-9(Z),11(E)-octadecadienoate (3b), α-tocopherol spirodiene dimer (4) and α-tocopherol trimer (5). When methyl linoleate containing α-tocopherol
was oxidized with AMVN under airsufficient conditions, the main products were 8a-alkyl-peroxy-α-tocopherones (2). In addition
to these compounds, 6-O-alkyl-α-tocopherols (1, 3a and 3b) were formed when the reaction was carried out under air-insufficient conditions. The results
indicate that α-tocopherol can react with both alkyl and alkylperoxyl radicals during the autoxidation of polyunsaturated
lipids. 相似文献
8.
α-Tocopherol was reacted with methyl linoleateperoxyl radicals at 37°C. The peroxyl radicals were generated by the reaction
of methyl linoleate with a free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile). The primary products of α-tocopherol with methyl linoleate-peroxyl radicals were isolated by
reversephase and normal-phase high performance liquid chromatography (HPLC), and their structures were characterized by ultraviolet
(UV), infrared (IR),1H and13C nuclear magnetic resonance (NMR) and mass spectrometry (MS). There were four stereoisomers of methyl 13-(8a-peroxy-α-tocopherone)-9(Z),11(E)-octadecadienoate and four stereoisomers of methyl9-(8a-peroxy-α-tocopherone)-10(E),12(Z)-octadecadienoate. 相似文献
9.
Michael WR 《Lipids》1966,1(5):365-368
This third paper presents the isolation and characterization of nonaromatic cyclic monomers formed from the heated linoleate.
The esters were isolated by a series of column chromatographic separations, followed by repeated gas chromatography to obtain
fractions containing C18 cyclic esters. Characterization of the esters was achieved by use of infrared, NMR, mass spectroscopy, and standard chemical
analyses. Also characterized were the isomers found in a complex mixture of cyclic monomers which had been partially separated
by column chromatography. Use of both physical and chemical methods of analyses permitted characterization of the mixture
of isomers without their having been separated from each other. 相似文献
10.
The rate of addition of hydrogen sulfide to high purity methyl oleate, methyl linoleate, methyl linolenate, methyl 9,11-trans,trans-octade-cadienoate and methyl β-eleostearate was investigated at 25 C with UV irradiation. A similar study was carried out
with soybean, linseed and tung oils in the absence and presence of 2,2′-azo-bis(isobutyronitrile) with UV photolysis. Initially
the reaction of hydrogen sulfide with methyl esters appears to follow pseudo-zero-order kinetics although as the reaction
proceeds the kinetics of the polyunsaturated ester reactions become more complex. For nonconjugated systems the overall rate
is determined by the initiation step, whereas the overall rate of addition to conjugated systems is a function of the stability
of the resonance-stabilized addition radical in the chain transfer step. For methyl esters the following order of reactivity
appears to hold:
Methyl oleate ≅ methyl linoleate ≅ methyl linolenate >> methyl 9,11-trans,trans-octadecadienoate > methyl β-eleostearate. Using 2,2′-azo-bis(isobutyronitrile) with UV photolysis markedly increases the
rate of addition of hydrogen sulfide to nonconjugated vegetable oils.
Presented at the AOCS Meeting, New York, October 1968.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
11.
Sprecher H 《Lipids》1968,3(1):14-20
Methyl 4-decenoate (10∶1ω6), methyl dodeca-3,6-dienoate (12∶2ω6), methyl tetradeca-5,8-dienoate (14∶2ω6) and methyl hexadeca-7,10-dienoate
(16∶2ω6) were prepared by total synthesis. Rats raised on a fat-deficient diet for 2 1/2 months received 100 mg per day of
one of the experimental acids or methyl linoleate for a period of 16 days. The liver lipids were extracted, converted to methyl
esters and analyzed by gas-liquid chromatography. Neither 10∶1ω6 nor 12∶2ω6 served as biosynthetic precursors for linoleate.
Small amounts of 14∶2ω6 were convered to linoleate while 16∶2ω6 served as an efficient precursor for linoleate and longer
chain ω6 acids. None of the short chain ω6 acids were incorporated directly into liver lipids. 相似文献
12.
S. A. Harrison L. E. Peterson D. H. Wheeler 《Journal of the American Oil Chemists' Society》1965,42(1):2-5
Previous work by Sutton, and by Harrison, McCaleb and Wheeler has shown that methyl stearate is converted to dimers plus higher
polymers by the action of di-t-butyl peroxide. The latter suggested that in the dimer, there was considerable linkage at carbon 2, the carbon α- to the
COOCH3 group, since the dimer ester was incompletely saponified by the usual procedures.
Further proof of α-linkage is now presented. A fraction which is predominantly α-,α′-linked dimer was isolated as the nonpolymeric
cyclic anhydride (α-,α′-dicetyl succinic anhydride) by molecular distillation from the linear polymeric non-α-linked polyanhydride.
The isolated cyclic anhydride appeared identical with a synthetic α-,α′-dicetyl succinic anhydride, whose synthesis is described.
The original dimer ester, the α-,α′-cyclic anhydride fraction, and the dimethyl ester derived from it, were examined by mass
spectrometry. The expected mol wt were confirmed by the parent ion peaks. Fragmentation patterns indicated appreciable α-linkage
in the original dimer ester, and almost exclusive α-linkage in the ester from the isolated cyclic anhydride. Aside from preference
for the α-position, joining appears to be randomly distributed.
Presented at AOCS Meeting, New Orleans, 1964. Journal Series No. 363. 相似文献
13.
A fractionally distilled C14−C16 fatty acid methyl ester, derived from palm oil, was sulfonated with gaseous SO3 in a falling film reactor to form an α-sulfo fatty acid methyl ester (α-SF; unbleached and unneutralized form). The included
dark-colored impurities were then separated from α-SF as a diethyl ether-insoluble matter. After purification by thin-layer
chromatography, the colored species were analyzed by ion-exchange chromatography, gel-permeation chromatography, and nuclear
magnetic resonance spectrometry. These data suggested that the colored species were polysulfonated compounds with conjugated
double bonds. Minor components in the raw fatty acid methyl ester, found by gas chromatography/mass spectrometry, were spiked
into the purified methyl palmitate and then sulfonated. The unsaturated methyl ester and hydroxy ester showed the worst color
results. The methyl oleate and methyl 12-hydroxystearate were then sulfonated and analyzed. Deep black products were obtained,
which showed the same properties as the colored species in α-SF. It was concluded that low levels of unsaturated fatty acid
methyl esters and hydroxy esters in the fatty acid methyl ester are the main causes of the coloring. 相似文献
14.
Methyl linoleate, diluted with an equal weight of methyl laurate, was heated without exclusion of air at 200C for 200 hours.
The reaction mixture was separated by means of molecular distillation, urea adduction, column chromatography, and gas chromatography.
Cyclic and aromatic materials were detected in the nonurea adductable monomer fractions. The dimer was separated into polar
and nonpolar fractions. Analytical data for the nonpolar dimer are consistent with a cyclic Diels-Alder product. Bioassays
showed the nonadductable monomer, the polar dimer, and a fraction of intermediate boiling point to be toxic when administered
to weanling male rats. Urea-adductable fractions, nonpolar dimer, and polymer were not toxic. The concentrations of the toxic
components were so low that the heated linoleate, before fractionation but after removal of the laurate, was not toxic. 相似文献
15.
Procedures are described for the rapid purification of gram quantities of methyl oleate, methyl linoleate, methyl α- and γ-linolenates
and methyl ricinoleate from appropriate natural oils by high pressure liquid chromatography (HPLC). 相似文献
16.
The 2, 4-dinitrophenylosazones of dicarbonyl compounds isolated from oxidized methyl linoleate were resolved by means of adsorption
and partition chromatography. Individual components were characterized by means of ultraviolet absorption, thin layer chromatographic
techniques for class determination and for separation of homologous series, column co-chromatography of authentics and the
unknowns, IR spectroscopy and melting point analysis. Evidence was obtained for the presence of glyoxal, methyl glyoxal, but-2-en-1,
4-dial, α-keto hexanal, α-keto heptanal, α-keto octanal, and α-keto nonanal.
Technical Paper No. 1864, Oregon Agricultural Experiment Station. 相似文献
17.
A. J. Stirton J. Turer R. W. Riemenschneider 《Journal of the American Oil Chemists' Society》1945,22(4):81-83
Summary The oxygen absorption of methyl linolenate, methyl linoleate, methyl oleate, methyl stearate, the distilled methyl esters
of lard, and various mixtures of the four individual methyl esters were measured at 100° C. in the Barcroft-Warburg apparatus.
Mixtures of methyl esters absorbed oxygen at a rate which could be approximately predicted from the rate of oxygen absorption
of each component and the percentage of each present.
The antioxidants nordihydroguaiaretic acid (NDGA), propyl gallate, benzylhydroquinone, α-tocopherol, and their synergistic
combinations with citric acid, d-isoascorbyl palmitate, and lecithin were tested with the substrates methyl linoleate, methyl
oleate, methyl stearate, and the distilled methyl esters of lard. Citric acid showed marked synergism with each antioxidant.
The two most effective were the combinations of citric acid with nordihydroguaiaretic acid and with propyl gallate.
One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, United
States Department of Agriculture. 相似文献
18.
K. Kuhajda J. Kandrac S. Dobanović-Slavica J. Hranisavljević D. Miljković 《Lipids》1993,28(9):863-865
Conjugated bile acids, namely glyco- and tauro-3α,6α-dihydroxy-5β-cholanoic acid (hyodeoxycholic acid), 3α,7α-dihydroxy-5β-cholanoic
acid (chenodeoxycholic acid), 3α,6α,7α-trihydroxy-5β-cholanoic acid (hyocholic acid) and 3α-hydroxy-6-oxo-5β-cholanoic acid
(6-keto-litocholic acid) were isolated from pig bile, and subsequently transformed into the corresponding methyl esters. Separation
of the methyl esters of the isolated bile acids by high-performance liquid chromatography (HPLC) was accomplished on a ZORBAX-CN
column (Dupont, Boston, MA) withn-hexane/2-propanol/methylene chloride (89∶6∶5, by vol) as the mobile phase containing traces (≈1%) of amyl alcohol and water
as moderators. HPLC analysis of the methyl esters also showed the presence of methyl 3α-hydroxy-6-oxo-5α-cholanoate, which
was probably produced in the course of alkaline hydrolysis of the conjugated bile acids. 相似文献
19.
The refractive indices of methyl oleate, linoleate, linolenate, erucate, and the saturated fatty acid methyl esters from acetate
to nonadecanoate have been measured at 20C and 40C for the Nad, H
α
, H
β
, H
γ
lines. The values for the saturated series have been correlated with the Smittenberg relation. Molar refractions have been
computed and checked for additivity. The limiting refractive indices obtained from the Smittenberg relation are compared to
those obtained from the molar refraction. 相似文献
20.
Suhail Ahmad F. Ahmad S. M. Osman 《Journal of the American Oil Chemists' Society》1984,61(9):1464-1465
The synthesis of substituted 1,3-dioxolanes from oxo fatty acid esters using 1,2-propanediol is described. This reagent, besides
forming dioxolanes, also converts the methyl ester to the 2′-hydroxy propyl ester. Methyl 10-oxoundecanoate gives 2′-hydroxy
propyl 10-(2″-methyl ethylene dioxolane) undecanoate (Ia, 75%) as a major product. Methyl 9-oxooctadecanoate reacts similarly
and yields 2′-hydroxy propyl 9-(2″-methyl ethylene dioxolane) octadecanoate (IIb, 60%), along with the minor products (IIa,
IIc). Methyl 2-oxooctadecanoate, after prolonged refluxing, affords only 2′-hydroxy propyl 2-(2″-methyl ethylene dioxolane)
octadecanoate (IIIa) in 70% yield. Structures of each reaction product were established on the basis of elemental analysis,
IR, NMR and a study of mass spectrometry. 相似文献