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1.
E. A. Emken E. N. Frankel R. O. Butterfield 《Journal of the American Oil Chemists' Society》1966,43(1):14-18
Hydrogenation of linseed and soybean methyl esters was achieved at 100–180C, 100–1000 psi H2 and 0.05–0.25 moles catalyst per mole of ester. The relative activity of metal acetylacetonates in decreasing order was:
nickel (III), cobalt (III), copper (II) and iron (III). Reduction occurred readily in methanol solution but only slowly in
dimethylformamide and acetic acid. No reduction occurred in the absence of solvents. Soybean oil was also hydrogenated rapidly
with nickel (III) acetylacetonate in methanol, but in this system the triglycerides were converted to methyl esters. Nickel
(III) acetylacetonate was the most selective catalyst toward linolenate hydrogenation. Methyl linoleate and linolenate hydrogenated
with nickel(III) acetylacetonate were fractionated into monoenes, dienes and trienes. Thecis monoenes separated in 62 to 68% yield had double bonds in the original position. The remainingtrans monoenes had extensively scattered unsaturation. The dienes and trienes showed no conjugation, but some of the double bonds
in the dienes were not conjugatable with alkali. Little stearate was formed.
Presented at AOCS meeting in Chicago, 1964
No. Util. Res. and Dev. Div. ARS, USDA 相似文献
2.
E. N. Frankel Helen M. Peters E. P. Jones H. J. Dutton 《Journal of the American Oil Chemists' Society》1964,41(3):186-191
Iron pentacarbonyl is an effective homogeneous catalyst for the reduction of polyunsaturated fats. Hydrogenation of soybean oil and its methyl esters has been achieved at 180C, hydrogen pressures of 100-1,000 psi, and 0.05–0.5 molar concentrations of catalyst. Analyses of partially reduced products show considerable isomerization of double bonds, reduction of linolenate and linoleate with little or no increase in stearate, and accumulation ofcis,trans- andtrans, trans-conjugated dienes, and isolatedtrans monoenes. The unreduced trienes include diene conjugated fatty esters. The nonconjugated dienes contain large amounts oftrans and nonalkali conjugatable unsaturation. Considerable scattering of double bonds is evident in different fractions between the C4 and C16 positions. Complex formation between iron carbonyl and unsaturated fats is also indicated. The course of the homogeneous hydrogenation catalyzed by iron pentacarbonyl appears similar to the heterogeneous catalytic reaction. Metal carbonyls are well known for their isomerizing effects and their ability to form stable complexes with olefins. These homogeneous complexes provide suitable model systems to study the mechanism of catalytic hydrogenation of fats. 相似文献
3.
S. Koritala 《Journal of the American Oil Chemists' Society》1980,57(9):293-298
The mechanism of hydrogenation at 900~950 psi with copper-chromite catalyst was investigated with pure methyl esters as well
as their mixtures. A comparison of double bond distribution intrans-monoenes formed during hydrogenation of linoleate and alkali-conjugated linoleate revealed that 85~95% of the double bonds
in linoleate conjugated prior to hydrogenation. The mode of hydrogen addition to conjugated triene and diene at high pressure
is similar to that at low pressure but positional and geometric isomerizations of unreduced conjugated esters were less at
high pressure. Geometric isomerization of methyl linoleate and linolenate was considerable at high pressure whereas it was
negligible at low pressure. The absence of conjugated products during hydrogenation of polyunsaturated fatty acid esters resulted
from their high reactivity. Conjugated dienes are 12 times more reactive than the triene, methyl linolenate, and 31 times
more reactive than the diene, methyl linoleate. The products of methyl linolenate hydrogenation were the same as those predicted
by the conjugation mechanism.
Presented at the 70th Annual Meeting of the American Oil Chemists' Society, San Francisco, April 29~May 3, 1979. 相似文献
4.
Polyunsaturated fatty acid methyl esters of soybean oil (MeSBO) were selectively conjugated as a means of increasing the linolenate
selectivity of various homogeneous and heterogeneous hydrogenation catalysts. Kinetics of the conjugation reaction in various
solvents indicated that linolenate conjugated 5–8 times faster than linoleate. Selective conjugation of MeSBO with potassiumt-butoxide in dipolar solvents resulted in an increase in linolenate hydrogenation selectivity to 7–8 with Ni and Pd heterogeneous
catalysts, and to 7–10 with homogeneous and heterogeneous chromium carbonyl catalysts.Trans-unsaturation in the hydrogenated products was only 1–3% with the chromium carbonyl catalysts, in contrast to 30–39% with
the heterogeneous metal catalysts. Triglycerides were readily converted to partial glycerides andt-butyl esters with the potassiumt-butoxide reagent.
Presented at the AOCS North Central Section Symposium, March 1980. 相似文献
5.
E. N. Frankel E. A. Emken V. L. Davison 《Journal of the American Oil Chemists' Society》1966,43(5):307-311
Iron pentacarbonyl is a powerful isomerization agent of unsaturated fatty esters. Highly conjugated fats are obtained when
polyunsaturated fatty esters are treated with an excess Fe(CO)5 to form complexes followed by decomposition of the complexes with FeCl3. Iron tricarbonyl complexes were prepared in 80 to 95% yields from methyl linoleate, linolenate and polyunsaturated fatty
esters of soybean, linseed and safflower oils by heating at 180–185C with 2 moles Fe(CO)5 per mole ester under nitrogen pressure. Decomposition of these complexes with FeCl3 resulted in 90 to 97% conjugation of the polyunsaturated fatty esters mainly in the alltrans configuration. Isolatedtrans unsaturation reached levels of 18 to 30%. Methyl oleate yielded 74%trans unsaturation but no complex of iron carbonyl was obtained.
Presented in part at AOCS meeting in Houston, 1965.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
6.
A. E. Johnston Helen M. ven Horst J. C. Cowan H. J. Dutton 《Journal of the American Oil Chemists' Society》1963,40(7):285-286
The effects of catalyst concentration and of temperature on linolenate selectivity,trans formation, and rate of hydrogenation have been studied for a commercial electrolytic nickel catalyst. Results obtained with
an equimixture of linoleate and linolenate, following the procedure previously described, are presented as isometric drawings,
which cover the experimentally practicable temperature ranges from 70–230C and nickel concentration from 0.05–10%. Whereas
the rate of hydrogenation depends upon both temperature and catalyst concentration,trans formation is essentially a function of temperature while selectivity is little influenced by either parameter.
Presented at the AOCS meeting in New Orleans, La., 1962.
A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U. S. D. A. 相似文献
7.
A micromethod for the localization of double bonds in unsaturated fatty acids via ozonolysis employing pyrolytic cleavage
of ozonides in the presence of a hydrogenation catalyst is described. Cleavage of the ozonides is carried out in a gasliquid
chromatographie instrument in a small glass tube, containing the catalyst, inserted in the top of the column opposite the
in input heaters at 225C. Ozonides of methyl esters of straight chain unsaturated fatty acids are cleaved through the action
of the catalyst to aldehyde fragments which are swept simultaneously into the column for analysis.
The double bond positions are deduced from the chain length of the fragments. The method is demonstrated on methyl oleate,
linoleate, linolenate and arachidonate.
Presented at the AOCS Meeting, Cincinnati, October, 1965. 相似文献
8.
S. Koritala R. O. Butterfield H. J. Dutton 《Journal of the American Oil Chemists' Society》1973,50(8):317-320
A mixture of methyl linoleate and alkali-conjugated methyl linoleate was reduced with nickel, palladium, platinum and copper-chromite
catalysts. The course of hydrogenation was followed by gas liquid chromatography of samples withdrawn at intervals. Relative
rate constants of reactants and inermediates were calculated by a computer. Conjugated linoleate was 10–18 times more reactive
than methyl linoleate with all catalysts except platinum, which showed no selectivity at 60 C. At 150 C conjugated diene reacted
four times faster than methyl linoleate with platinum catalyst. A conjugated diene-to-stearate shunt was observed with palladium
and platinum catalysts. When β-eleostearate was hydrogenated with the same catalysts, 50–97% of the triene was reduced directly
to monoene with all catalysts except copper chromite, which selectively reduced conjugated triene to conjugated diene. On
the basis of present kinetic data and previous knowledge about the mode of hydrogen addition to conjugated systems, a scheme
has been proposed to account for the products formed during hydrogenation of methyl linolenate.
ARS, USDA. 相似文献
9.
Selective Hydrogenation of Fats and Derivatives Using Ziegler-Type Organometallic Catalysts IV: Distribution of Isomers during Hydrogenation of Polyunsaturated Fatty Acid Methylesters Hydrogenation of methyl linoleate using a Ziegler-type catalyst, containing nickel stearate and triethyl aluminium, proceeds mainly without previous conjugation or trans-isomerization. Both olefinic double bonds are hydrogenated with equal probability. As long as the reaction mixture contains double unsaturated esters, these compounds are inhibiting hydrogenation and isomerization of single unsaturated esters. During hydrogenation of methyl linolenate there is only less selectivity to formation of methyl linoleate. Intermediate product is a mixture of single and double unsaturated fatty acid methylesters. In the latter compounds after consumption of triple unsaturated esters both double bonds are separated by two or more methylene groups. Polyenic compounds with 1,4-position of olefinic double bonds are preferably hydrogenated than polyenic compounds with greater distance between the double bonds. 相似文献
10.
Carbonyl complexes of Cr, Mo and W have been studied as soluble catalysts for the hydrogenation of methyl sorbate and of methyl
esters from soybean oil. With methyl sorbate, relative catalytic activity decreased in the approximate order: mesitylene-Mo(CO)3, cycloheptatriene-Mo(CO)3, cycloheptatriene-Cr(CO)3, bicyclo (2,2,1) hepta-2,5-diene-Mo(CO)4, chlorobenzene-Cr(CO)3, methyl benzoate-Cr(CO)3, mesitylene-W(CO)3, benzene-Cr(CO)3, toluene-Cr(CO)3, mesitylene-Cr(CO)3, and hexamethylbenzene-Cr(CO)3. Order of catalytic activity was related to thermal stability of the complexes during hydrogenation. With mesitylene-M(CO)3 complexes, selectivity varied in the order Cr>Mo>W. Under certain conditions the mesitylene complexes of W, Cr and Mo reduced
methyl sorbate respectively to methyl 2-, 3-, and 4-hexenoates as main products.
The more active and thermally stable Cr(CO)3 complexes catalyzed effectively the hydrogenation of linoleate and linolenate in soybean oil esters with little or no stearate
formation. The hydrogenated products formed with the benzoate complex at 165–175 C contained 50–67% monoene, 18–30% diene,
2–7% conjugated diene, and only 3–7%trans unsaturation. Linolenate-linoleate selectivity values varied from 3 to 5 and linoleate-oleate selectivity from 7 to 80. Monoene
fractions had 40–50% of the double bond in the C-9 position; the rest of the unsaturation was distributed mainly between the
C-10 and C-12 positions. Conjugation is apparently an intermediate step in the hydrogenation of linoleate and linolenate.
The Cr(CO)3 complexes are unique in catalyzing the hydrogenation of polyunsaturated fatty esters to monounsaturated fatty esters of lowtrans content.
Presented at AOCS-AACC Joint Meeting, Washington, D.C. April, 1968.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
11.
The effect of iron catalyst and the advantages of its use in thiocyanogen additions to a series of unsaturated acids and esters
were studied. In the absence of catalyst, the deactivation effect of the carboxylic group on the double bond is observed up
to and including the Δ5 position, conversions to products are low, and the products in some cases are not the anticipated dithiocyanate adducts.
These normally unreactive double bonds are induced to react with thiocyanogen by iron catalyst. Furthermore, for the catalyzed
reactions of Δ2 and Δ3 acids and esters, the esters are found to be more reactive than the acids, although both produce trace to low yields of adducts.
Single isolated bonds located in any position beyond Δ3, including terminal, are thiocyanated rapidly and in high yield in the presence of iron catlyst. Methyl linoleate and methyl
linolenate form ca. 80% of the tetrathiocyanate and hexathiocyanate adducts, respectively.
Presented at the AOCS Meeting, Chicago, September 1976 相似文献
12.
Sambasivarao Koritala 《Journal of the American Oil Chemists' Society》1970,47(8):269-272
β-Eleostearate was found to be reduced by 1,6 addition of hydrogen. Because of the extensive isomerization of conjugated trienes
during hydrogenation, the occurrence of 1,2 and 1,4 addition reactions could not be proven. Conjugated dienes were reduced
by both 1,2 and 1,4 addition of hydrogen. The double bond distribution in the products formed from linoleate, linolenate and
their isomers was consistent with the assumption that the double bonds in polyunsaturated fatty esters conjugate and then
add hydrogen. Extensive isomerization (positional and geometric) of the conjugated double bond systems occurred during hydrogenation.
Monoenes were not isomerized under similar conditions of hydrogenation. Since double bond distribution in monoenes formed
from linoleate and alkali-isomerized linoleate was identical, indications are that conjugation precedes hydrogenation.
Presented in part at the symposium “Hydrogenation Process,” Division of Industrial Engineering Chemistry, 157th American Chemical
Society Meeting, Minneapolis, April 1968.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
13.
Photosensitized oxidation of unsaturated fatty acid methyl ester was carried out using methylene blue as a sensitizer. Oxidation
products, monohydro-peroxides, were identified as trimethylsilyl derivatives. Methyl oleate gave the 9- and 10-isomers; methyl
linoleate, the 9-, 10-, 12-, and 13-isomers; and methyl linolenate, the 9-, 10-, 12-, 13-, 15-, and 16-isomers, respectively.
The double bond to which the hydroperoxide group attached was shifted to the adjacent position in each isomer. Thus, both
conjugated and nonconjugated isomers were present in methyl linoleate monohydroperoxides and methyl linolenate monohydroperoxides.
By the inhibition experiment, it was ascertained that the above reaction proceeded via singlet oxygen. The relative rates
of methyl oleate, methyl linoleate, and methyl linolenate were 1.0∶1.7∶2.3, respectively. These results obtained from the
methyl esters were applied to the photosensitized oxidation of triglycerides purified from vegetable oils, and the reaction
mechanism on triglycerides was proposed. 相似文献
14.
A previous study of autoxidation products by high pressure liquid chromatography (HPLC) of methyl oleate and linoleate was
extended to methyl linolenate. Autoxidized methyl linolenate was fractionated by HPLC either after reduction to allylic alcohols
on a reverse phase system, or directly on a micro silica column. Isolated oxidation products were characterized by thin layer
and gas liquid chromatography and by ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Secondary products
from the autoxidation mixtures (containing 3.5–8.5% monohydroperoxides) included epoxy unsaturated compounds (0.2–0.3%), hydroxy
or hydroperoxy-cyclic peroxides (3.8–7.7%), epoxy-hydroxy dienes (<0.1%), dihydroxy or dihydroperoxides with conjugated diene-triene
and conjugated triene systems (0.9–2.9%). Cyclization of the 12- and 13-hydroperoxides of linolenate would account for their
lower relative concentration than the 9- and 16-hydroperoxides. Dihydroperoxides may be derived from the 9- and 16-linolenate
hydroperoxides. Cyclic peroxides and dihydroperoxides are suggested as important flavor precursors in oxidized fats. 相似文献
15.
W. G. Bickford P. Krauczunas D. H. Wheeler 《Journal of the American Oil Chemists' Society》1942,19(2):23-27
Summary 1. The non-conjugated unsaturated fatty acid esters react with maleic anhydride at 200° C. or above.
2. At 200° C., methyl oleate reacts with almost 1 mole, methyl linoleate with 2 moles, and methyl linolenate with 2.5 moles
of maleic anhydride, when an excess of anhydride is present. Methyl stearate reacts negligibly.
3. Methyl oleate reacts without affecting unsaturation.
4. The first molecule of anhydride reacting with methyl linoleate reacts mostly to saturate one double bond, while the second
one adds on without affecting unsaturation.
5. The first two molecules of anhydride reacting with methyl linolenate react mostly to saturate one double bond each, while
the third molecule adds on without affecting unsaturation.
6. The possible structures of the reaction products have been discussed.
Presented before the American Oil Chemists’ Society at their meeting in Chicago, October 8–10, 1941.
Now associated with the Southern Regional Research Laboratory, New Orleans, Louisiana.
A cooperative organization participated in by the Bureaus of Agricultural Chemistry and Engineering and Plant Industry of
the U. S. Department of Agriculture, and the Agricultural Experiment Stations of the North Central States of Illinois, Indiana,
Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin. 相似文献
16.
The need for a selective catalyst to hydrogenate linolenate in soybean oil has prompted our continuing study of various model
triunsaturated fats. Hydrogenation of methylβ-eleostearate (methyltrans,trans,trans-9,11,13-octadecatrienoate) with Cr(CO)3 complexes yielded diene products expected from 1,4-addition (trans-9,cis-12- andcis-10,trans-13-octadecadienoates). Withα-eleostearate (cis,trans,trans-9,11,13-octadecatrienoate), stereoselective 1,4-reduction of thetrans,trans-diene portion yielded linoleate (cis,cis-9,12-octadecadienoate). However,cis,trans-1,4-dienes were also formed from the apparent isomerization ofα- toβ-eleostearate. Hydrogenation of methyl linolenate (methylcis,cis,cis-9,12,15-octadecatrienoate) produced a mixture of isomeric dienes and monoenes attributed to conjugation occurring as an intermediate
step. The hydrogenation ofα-eleostearin in tung oil was more stereoselective in forming thecis,cis-diene than the corresponding methyl ester. Hydrogenation of linseed oil yielded a mixture of dienes and monoenes containing
7%trans unsaturation. We have suggested how the mechanism of stereoselective hydrogenation with Cr(CO)3 catalysts can be applied to the problem of selective hydrogenation of linolenate in soybean oil.
No. Market. Nutr. Res. Div., ARS, USDA. 相似文献
17.
E. Klenk 《Journal of the American Oil Chemists' Society》1965,42(7):580-582
Feeding experiments with C14-labeled and unlabeled unsaturated fatty acids have been used to study the possible routes of formation of the C20- and C22-polyenoic fatty acids of rat liver phosphatides. The acids of the palmitoleate, oleate, linoleate, and linolenate types (considered
on the basis of the position of the double bond closest to the methyl end) are apparently formed from the C16 and C18 unsaturated acids of the corresponding types. The results rule out possible transformations of the C20- and C22-polyenoic acids from one type to another, and demonstrate the exclusive introduction of new double bonds toward the carboxyl
group. Isomers of linoleate or linolenate in which the double bonds were shifted by one carbon atom toward the carboxyl or
methyl groups were incorporated into the phosphatides only to a negligible extent in the form of polyenoic acids. 相似文献
18.
The ultrasonic sound velocity of the unsaturated fatty acid methyl esters from acetate to nonadecanoate, methyl oleate, linoleate,
linolenate, and erucate have been measured at 20C and 40C in the liquid state. Data of the saturated compounds were correlated
with the Smittenberg relation and a reasonable fit was noted. The molar sound velocity according to Rao was computed from
the observed values and increments for the CH2 group and for the double bond are presented. 相似文献
19.
S. Koritala J. P. Friedrich T. L. Mounts 《Journal of the American Oil Chemists' Society》1980,57(1):1-5
Soybean oil was partially hydrogenated with copper-chromite catalyst at 170 C and up to 30,000 psig hydrogen pressure. Catalyst
activity increased with increase in pressure up to 15,000 psig. The linolenate selectivity (SLn) of the reaction remained essentially unchanged over 50–1000 psig pressure range. A SLn of 5.5 to 5.6 was achieved at 15,000 to 30,000 psig pressure range. This value is somewhat lower than the selectivity at
50–1000 psig, but much higher than that obtained with nickel catalysts. Geometric isomerization increased as pressure increased
up to 200 psig; above this pressure, the percenttrans remained the same up to 500 psig.trans Isomer content decreased when the pressure was increased to 30,000 psig. cis,trans Isomerization of linoleate was greater at 1000 psig and 15,000 psig than at 50 psig. At 15,000 psig, part of the linoleate
in soybean oil was hydrogenated directly without prior conjugation, whereas at low pressures, all of the double bonds first
conjugate prior to hydrogenation. This difference in mechanism might explain the lower selectivities obtained at high pressures.
Conjugated diene isomers were found in the products up to 200 psig. Above this pressure conjugated diene was not measurable.
No significant differences were found in the double bond distribution oftrans monoenes even though the amount oftrans monoene formed decreased as pressure was increased to 30,000 psig.
1 Presented at the AOCS meeting, San Francisco, May 1979. 相似文献
20.
C. R. Scholfield Janina Nowakowska H. J. Dutton 《Journal of the American Oil Chemists' Society》1960,37(1):27-30
Summary Acetonitrile-pentane-hexane makes a desirable solvent system for preparation of pure methyl esters because of its immiscibility,
selectivity toward unsaturation, low boiling point, stability, and ease of recovery. Since separated esters are removed from
the apparatus dissolved in the pentane-hexane layer, successive batches may be fractionated without removing the acetonitrile
layer from the instrument. Applications have been illustrated for the preparation of methyl linolenate from an 85% linolenate
concentrate, methyl linoleate from safflower esters, and methyl arachidonate from pig liver lipids.
This procedure provides a source of “natural” fatty acids with the double bond configuration unchanged, in contrast to those
from the conventional bromination-debromination process. Automation of the process is completed by use of a recording refractometer
which monitors concentration of solutions issuing from the extractor. Resolutions to be anticipated with lesser numbers of
extraction tubes than 200 are calculated for an equal mixture of linoleate and linolenate.
Presented at the 50th meeting, American Oil Chemists' Society, New Orleans, La., April 20–22, 1959.
This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department
of Agriculture. 相似文献