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1.
Pure conjugated isomers of linoleic acid were prepared on a large scale by alkali-isomerization of purified methyl linoleate.
The methyl esters of alkali-isomerized linoleic acid contained mainly the methyl cis-9, trans-11- and trans-10, cis-12-octadecadienoates (44 and 47%, respectively). These two isomers were then separated and purified by a series of low-temperature
crystallizations from acetone. The isomeric purity obtained for the cis-9, trans-11-octadecadienoate isomer was >90% and that of the trans-10, cis-12-octadecadienoate isomer was 89 to 97%. The isolated yield of the two isomers corresponded to 18 and 25.7%, respectively,
of the starting material. The structure of the two isomers was confirmed using partial hydrazine reduction, silver nitrate-thin-layer
chromatography of the resulting monoenes and gas chromatography coupled with mass spectrometry of the 4,4-dimethyloxazoline
derivatives. Fourier transform infrared spectroscopy of the monoenes gave the confirmation of the geometry of each double
bond. 相似文献
2.
The partial hydrogenation of mixtures of methyl cis 6-, cis 9- and cis 12-octadecenoates followed by the determination of the unreacted monoenes indicated the double bonds in these positions are
hydrogenated at the same rates. However, study of a hydrogenation under high isomerization conditions indicated the double
bonds very near the carboxyl hydrogenate faster than those near the terminal methyl.
Presented at the AOCS Meeting in Atlanta, 1963. 相似文献
3.
Methyl cis-9, cis-15-octadecadienoate was partially deuterated with nickel catalyst, and the product was separated into saturate, monoene and
diene fractions. Monoenes were separated into trans and cis fractions, and dienes into trans,trans, cis,trans and cis,cis fractions. Monoene isomers with double bonds at the 9 and 15 positions predominated in both cis- and trans-monoene fractions. Considerable amounts of isomers with double bonds situated on either side of the original 9 and 15 positions
were found in the trans-monoene fraction. Diene was extensively isomerized to positional and geometrical isomers, and deuterium was incorporated
into these isomers. Double bond migration was greatest in trans,trans-dienes and smallest in cis,cis-dienes. The amount of deuterium in the dienes was proportional to the extent of isomerization experienced by the dienes.
ARS, USDA. 相似文献
4.
Methyl cis-9, cis-15-octadecadienoate was used as a model for the hydrogenation of methyl linolenate. Homogeneous catalysis by platinum, palladium
and nickel complexes produced a mixture of isomeric monoenes similar to that from the hydrogenation of methyl linolenate.
These catalysts are, therefore, capable of promoting isomerization of isolated double bonds and of producing conjugated dienes
which are necessary for the formation of monoenes.
N. Market, and Nutr. Res. Div., ARS, USDA. 相似文献
5.
Alkali-conjugated linoleate ( cis-9, trans-11- and trans-10, cis-12-octadecadienoate) was hydrogenated with nickel, palladium and platinum catalysts. The trans and cis monoenes formed during reduction were isolated, and their double bond distribution was determined by reductive ozonolysis
and gas liquid chromatography. About 44–69% of the monoenes were composed of δ 10 and δ 11
trans monoene isomers, whereas the δ 9 and δ 12
cis monoenes amounted to 20–26%. With nickel catalyst, composition of monoene isomers remained the same, even when the hydrogenation
temperature was increased. The monoene isomer profiles between nickel and palladium catalysts were indistinguishable. Isomerization
of monoenes with platinum catalyst was suppressed at 80 psi. The position of the double bonds in unreacted conjugated diene
was always retained, except with nickel at both temperatures and with platinum at 150 C when a slight migration occurred.
Geometrical isomerization to trans,trans-conjugated diene was observed in the unreacted diene with nickel (ca. 15% of diene) at both 100 C and 195 C, and with platinum
(ca. 7% of diene) at 150 C.
ARS, USDA. 相似文献
6.
The aim of the present study was to investigate the effect of cis-9, trans-11 and trans-10, cis-12 CLA on FA composition of TAG in epididymal adipose tissue and liver, and of hepatic phospholipids PL. Twenty-four Syrian
Golden hamsters were randomly divided into three groups of eight animals each and fed semipurified atherogenic diets supplemented
with either 0.5 g/100g diet of linoleic acid or cis-9, trans-11 or trans-12, cis-9 CLA for 6 wk. Total lipids were extracted, and TAG and PL were separated by TLC. FA profile in lipid species from liver
and adipose tissue, as well as in feces, was determined by GC. Trans-10, cis-12 CLA feeding significantly reduced linoleic and linolenic acids in TAG from both tissues, leading to reduced total PUFA
content. Moreover, in the epididymal adipose tissue docosenoic and arachidonic acids were significantly increased. In liver
PL, although no changes in individual FA were observed, total saturated FA (SFA) were decreased. No changes in TAG and PL
FA profiles were induced by the cis-9, trans-11 CLA. TAG and PL incorporated cis-9, trans-11 more readily than trans-11, cis-12 CLA. This difference was not due to differential intestinal absorption, as shown by the analysis of feces. We concluded
that only trans-10, cis-12 CLA induces changes in FA composition. Whereas increased PUFA content was observed in either liver or adipose tissue TAG,
decreased SFA were found in liver PL. Incorporation of cis-9, trans-11 CLA in TAG is greater than that of trans-10, cis-12 CLA, but this is not due to differences in intestinal absorption. 相似文献
7.
To understand the heat-induced cis-trans isomerization of ethylenic bonds in octadecatrienoic acids, pine seed oil, which contains the unusual nonmethylene-interrupted
pinolenic ( cis-5, cis-9, cis-12 18∶3) acid as a major component, was heated under vacuum at 240°C for 6 h together with linseed and borage oils. As a
results, a small percentage of pinolenic acid undergoes cis-trans isomerization. The main isomer that accumulates is the trans-5, cis-9, trans-12 18∶3 acid. Minor amounts of the three mono- trans isomers are also present. Identification of isomers was realized by combining gas-liquid chromatography on a CP Sil 88 capillary
column, argentation thin-layer chromatography and comparing the equivalent chainlengths of artifacts to those of isomers present
in NO 2-isomerized pine seed oil. Hydrazine reduction was used to demonstrate that there was no positional shift of double bonds.
Heat-induced geometrical isomerization of pinolenic acid differs from that of α- and γ-linolenic acids in at least two aspects.
The reaction rate is slower (about one-fourth), and mono- trans isomers are formed in low amounts. 相似文献
8.
The conjugated linoleic acid methyl cis-9, trans-11-octadecadienoate has been prepared on a large scale from methyl ricinoleate. Methyl ricinoleate was purified from castor
esters by a partition method. It was converted to the mesylate, which was reacted with a base (1,8-diazabicyclo[5,4,0]-undec-7-ene)
to give a product that contained 66% of the desired ester. Two urea crystallizations produced a product containing 83% methyl
cis-9, trans-11-octadecadienoate, the identity of which was confirmed by gas chromatography linked to mass spectrometry and by Fourier
transform infrared spectroscopy. The remaining impurities were methyl cis-9, cis-11- and cis-9-, trans-12-octadecadienoate. 相似文献
9.
Determination of the relative reaction rates of isomeric methyl octadecadienoates is possible by competitive reduction of a mixture containing an inactive diene and a radioactively labeled isomer. The hydrogenation rate of methylcis-9,cis-12-octadecadienoate with platinum and nickel catalysts is compared to the hydrogenation rate of each of several isomers of methyl octadecadienoate, and the relative rate of the competitive hydrogenations is calculated by a digital computer. Methylcis-9,cis-12 linoleate is reduced the most rapidly of all the dienes studied. The relative rates of the positional isomers tend to decrease with the increasing number of methylene groups between the double bonds, except when one of the double bonds is in the more reactive 15 position. Comparison of the geometric isomers shows thattrans,trans diene is hydrogenated at a slower rate thancis,cis linoleate. 相似文献
10.
The ratio of absorptivity at 10.2 µm and 10.6 µm differs between methyl cis-9, trans-11-, and trans-10, cis-12-octadecadienoates. For the cis-9, trans-11-ester, a 10.2 µm/a 10.6 µm is in the range of 1.1–1.2; for the trans-10, cis-12-ester, it is 1.3–1.4. These differences in absorptivities are great enough to affect significantly compositions calculated from IR absorption. 相似文献
11.
It has been previously established that trans-10, cis-12 CLA is a potent inhibitor of milk fat synthesis. Although the mechanism of this action is not completely understood, it
has been speculated that eicosanoid-like metabolites of this isomer formed by the activity of tissue desaturases may be responsible
for its activity. The objective of this study was to investigate the effects of an enrichment containing an 18∶3 conjugated
diene, produced in the metabolism of trans-10, cis-12 CLA, on milk fat synthesis. Three rumen-fistulated Holstein cows (210±8 d in milk) were randomly assigned in a 3×3 Latin
square experiment. Treatments were (i) control, (ii) trans-10, cis-12 CLA supplement (2.1 g/d; positive control), (iii) enrichment providing two conjugated diene 18∶3 isomers (2.6 g/d of cis-6, trans-10, cis-12 and 4.0 g/d of cis-6, trans-8, cis-12) and trans-10, cis-12 CLA (2.1 g/d). Treatments were abomasally infused for 5 d at 4-h intervals, and there was a 7-d interval between periods.
Milk yield, dry matter intake, and milk protein yield were unaffected by treatments. In contrast, the trans-10, cis-12 CLA supplement reduced milk fat yield by 27%, whereas the supplement enriched with conjugated diene 18∶3 isomers (treatment
iii) had no effect on milk fat yield beyond that attributable to its trans-10, cis-12 CLA content. The transfer efficiency of trans-10, cis-12 CLA into milk fat was 25 and 24% for treatments ii and iii, respectively. At the same time, the abomasally infused conjugated
diene 18∶3 isomers were transferred to milk fat with an efficiency of 33 and 41% for cis-6, trans-10, cis-12 and cis-6, trans-8, cis-12 18∶3, respectively. Overall, short-term abomasal infusion of the conjugated diene 18∶3 isomers had no effect on milk fat
synthesis, thereby offering no support for an involvement of metabolies of trans-10, cis-12 CLA in the regulation of milk fat synthesis. 相似文献
12.
Column chromatography on silver ion-saturated Amberlyst XN 1010 cation exchange resin gave very good separation of a mixture
of methyl 12-hydroxy- cis-and trans-9-octadecenoates and of methyl threo-12, 13-dihydroxy- cis- and trans-9-octadecenoates. Comparison of the retention volumes of nonhydroxy, monohydroxy, and dihydroxy saturated and monoenoic methyl
esters and of dienoic methyl esters shows that the hydroxy group interacts with the column packing to slow passage of the
compound through the column, although the effect of a hydroxy group is less than that of a trans double bond. The effects of the hydroxy groups are additive; the ratio of retention volumes of dihydroxy ester to monohydroxy
ester is slightly larger that that of monohydroxy ester to nonhydroxy ester. The retention volume of a cis monoenoic ester
is equal to that of a hydroxy trans monoenoic ester and that of a hydroxy cis monoenoic ester is equal to that of a dihydroxy trans monoenoic ester. 相似文献
13.
To understand the cis-trans isomerization reaction of ethylenic bonds in heated octadecatrienoic acids (occurring during industrial deodorization of
oils), we have prepared a mixture of cis-9, cis-12, cis-15, and cis-9, cis-15 18:2 acids by partial hydrazine reduction of cis-9, cis-12, cis-15 18:3 acid present in linseed oil. This mixture (as fatty acid methyl esters) was heated under vacuum at 270°C for 2.25
h. The two methylene-interrupted acids isomerize at a similar rate under such conditions, but the nonmethylene-interrupted cis-9, cis-15 18:2 acid remains unchanged. This means that the mechanism of isomerization does not involve a direct interaction between
the two external ethylenic bonds as previously hypothesized. The central cis-12 ethylenic bond is apparently necessary for the isomerization of the two external cis-9 and cis-15 ethylenic bonds. However, this bond is itself rather protected against isomerization in the original cis-9, cis-12, cis-15 18:3 acid which is mainly isomerized to trans-9, cis-12, trans-15, cis-9, cis-12, trans-15, and trans-9, cis-12, cis-15 18:3 acids. The cis-9, trans-12, cis-15 18:3 isomer is less than 10% of total trans isomers of α-linolenic acid. As a general rule, only one of the two double bonds in a methylene-interrupted diethylenic system
can undergo cis-trans isomerization when submitted to heat treatment, at least for temperatures equal to or less than 270°C. 相似文献
14.
A major constituent fatty acid (31.2%) from Calea urticaefolia (Mill.) DC. seed oil is the previously unknown trans-3, cis-9, cis-12-octadecatrienoic acid. The oil also contains 2.2% of an unidentified acid and others with gas-liquid chromatographic characteristics
that correspond to the conventional fatty acids: myristic, 0.1%; palmitic, 9.3%; stearic, 2.9%; oleic, 5.3%; and linoleic,
48.9%.
Presented at the AOCS Meeting in New Orleans, 1964.
No. Utiliz. Res. & Dev. Div., ARS, USDA. 相似文献
15.
The catalytic activity and selectivity for hydrogenation of linoleic acid were studied on Ni, Cu, and Pd catalysts. A detailed
analysis of the reaction product was performed by a gas-liquid chromatograph, equipped with a capillary column, and Fourier
transform-infrared spectroscopy. Geometrical and positional isomerization of linoleic acid occurred during hydrogenation,
and many kinds of linoleic acid isomers ( trans-9,trans-12; trans-8,cis-12 or cis-9,trans-13; cis-9,trans-12; trans-9,cis-12 and cis-9,cis-12 18∶2) were contained in the reaction products. The monoenoic acids in the partial hydrogenation products contained eight
kinds of isomers and showed different isomer distributions on Ni, Cu, and Pd catalysts, respectively. The positional isomers
of monoenoic acid were produced by double-bond migration during hydrogenation. On Ni and Pd catalysts, the yield of cis-12 and trans-12 monoenoic acids was larger than that of cis-9 and trans-9 monoenoic acids. On the contrary, the yield of cis-9 and trans-9 monoenoic acids was larger than that of cis-12 and trans-12 monoenoic acids on Cu catalyst. From these results, it is concluded that the double bond closer to the methyl group (Δ12)
and that to the carboxyl group (Δ9) show different reactivity for hydrogenation on Ni, Cu, and Pd catalysts. Monoenoic acid
formation was more selective on Cu catalyst than on Ni and Pd catalysts. 相似文献
16.
Methyl cis-9, cis-12-octadecadienoate (methyl linoleate; c9, c12) and the corresponding cis,trans and trans.trans geometric isomers ( c9, t12 and t9, t12) were hydrogenated at 40 C and atmospheric hydrogen pressure in acetone as solvent, with nonmetallic palladium-on-resin
catalyst. These catalysts were prepared by impregnation of cationic exchange resins with an aqueous solution of palladium
dichloride. The methyleneinterrupted dienes were hydrogenated to the monoene stage with almost infinite selectivity, especially
with c9, c12, whereas t9, t12 was hydrogenated somewhat less selectively. The latter isomer was reduced considerably more slowly than the first, whereas c9, t12 occupied an intermediate position. The hydrogenation proceeded for an important part via a straightforward reduction of
one of the double bonds, though conjugation prior to hydrogenation also occurred. The methylene-interrupted dienes isomerized
to a high degree geometrically during hydrogenation, but they scarcely isomerized positionally, resulting in small amounts
of inactive ethylene-interrupted dienes. 相似文献
17.
We investigated the effects of conjugated linoleic acid (CLA) preparations, which were enriched for the cis-9, trans-11 CLA isomer or the trans-10, cis-12 CLA isomer, on body composition in mice. Body composition changes (reduced body fat, enhanced body water, enhanced body
protein, and enhanced body ash) were associated with feeding the trans-10, cis-12 CLA isomer. In cultured 3T3-L1 adipocytes, the trans-10, cis-12 isomer reduced lipoprotein lipase activity, intracellular triacylglycerol and glycerol, and enhanced glycerol release
into the medium. By contrast, the cis-9, trans-11 and trans-9, trans-11 CLA isomers did not affect these biochemical activities. We conclude that CLA-associated body composition change results
from feeding the trans-10, cis-12 isomer. 相似文献
18.
Geometrical isomers of methyl linoleate were reacted with alakli, and the resulting conjugated isomers were separated into trans,trans;cis,trans; and cis,cis fractions. The position of double bonds in the various fractions was determined by reductive ozonolysis. trans-9, trans-12-Isomer of linoleate formed trans,trans- and cis,trans-conjugated dienes, whereas cis-9, trans-12- and trans-9, cis-12-isomers in addition formed cis,cis-conjugated dienes. The formation of the products is in accordance with the theoretical predictions. During conjugation trans double bonds shifted to form a trans bond preferentially. During conjugation of cis-9, trans-12- and trans-9, cis-12-linoleate isomers, the cis double bond shifted preferentially over the trans double bond. A small amount of diene not conjugated was probably a geometrical and positional isomer of the starting material. 相似文献
19.
Methyl cis-9, cis-12-octadecadienoate (methyl linoleate; c9, c12), its t10, t12 and t10, c12 isomers and methyl cis-9-octadecenoate (methyl oleate; c9) were hydrogenated with rhodium complexes, the active species of which consisted of [RhL 2] + and [RhL 2H 2] + with ligands L=P(C 2H 5) 2C 6H 5 (catalyst A) P(i-C 4H 9) 3 (catalyst B) and P(CH 3) 3 (catalyst C). Using these catalysts the influence of steric effects on the reaction mechanism of hydrogenation of dienes
was studied. The reactions were carried out in 2-propanol at atmospheric hydrogen pressure and ambient temperature. During
hydrogenation of c9 on catalysts A and B, geometrical isomerization mainly occurred, whereas on catalyst C some positional isomerization also
took place. C9, c12 was almost exclusively hydrogenated via conjugated intermediates on catalyst A. On catalyst C, one of the double bonds
was hydrogenated directly, in most cases. In the absence of hydrogen, catalysts A and B conjugated c9, c12 very fast. The conjugation activity of catalyst C was much lower. Catalyst C showed a high 1,5-shift activity for the conjugated cis, trans and trans, cis intermediates during hydrogenation, in contrast to catalysts A and B, which showed a poor activity in this respect. T10, t12 was hydrogenated almost exclusively via 1,4-addition of hydrogen to the cisoid conformation, whereas only a slight preference was found in this mechanism over 1,2-addition for the hydrogenation of t10, c12. On the sterically unhindered catalysts A and C the trans double bond in t10, c12 was preferentially hydrogenated whereas on catalyst B, with its bulky ligands, the cis double bond was reduced faster than the trans double bond. 相似文献
20.
Summary Methyl cis-10, cis-12-octadecadienoate was prepared and found to have an ultraviolet absorption peak at 235 mμ, α=95. The infrared spectrum
revealed no diagnostic peaks for the cis,cis conjugated system.
The hydrogenation of the ester showed that when one mole of hydrogen was added, 1–2, 1–4, and 3–4 addition took place with
equal ease to produce an equimolar mixture of cis-10-, trans-11-, and cis-12-octadecenoates. An explanation of the reaction is offered on the basis of the structure of the diene system. 相似文献
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