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1.
G. Ben-Et A. Dolev M. Schimmel R. Stern 《Journal of the American Oil Chemists' Society》1972,49(4):205-207
A new approach to the selective hydrogenation of unsaturated fatty acids is suggested. It consists of a two step process.
The first is a selective conjugation of the double bonds, while the second consists of the hydrogenation reaction using a
catalyst which is specific to conjugated systems. Potassiumt-butoxide was used as a conjugation catalyst and its activity and selectivity were tested at various concentrations, different
molar ratios of catalyst to oil, and in various solvents. Phenanthrene chromium tricarbonyl was used as the hydrogenation
catalyst and its activity tested at various concentrations, temperatures and in various solvents.
UN Expert, Physical Organic Chemist. 相似文献
2.
E. N. Frankel E. P. Jones V. L. Davison E. Emken H. J. Dutton 《Journal of the American Oil Chemists' Society》1965,42(2):130-134
Homogeneous hydrogenation of unsaturated fats by cobalt carbonyl has been compared with the previously reported catalysis
by iron carbonyl. Soybean methyl esters, methyl linoleate and linolenate have been hydrogenated at 75–180C, 250–3,000 psi
H2 and 0.02 molar concn of catalyst. The cobalt carbonyl catalyst is more active at lower temp than iron carbonyl. The partially
reduced products are similar to those observed with iron carbonyl, but the reaction differs in showing much less accumulation
of conjugated dienes, no selectivity toward linolenate, almost complete absence of monoene hydrogenation to saturates, less
double bond migration and moretrans isomerization. No evidence was found for a stable complex between cobalt carbonyl and unsaturated fats as previously observed
with iron carbonyl. The rates of hydrogenation/double bond were the same for linoleate and linolenate on one hand, and for
alkali-conjugated linoleate and nonconjugated linoleate on the other.
Presented at AOCS Meeting in Minneapolis, 1963.
A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, USDA. 相似文献
3.
The isomerization reaction of methyl linoleate and methyl linolenate with potassiumt-butoxide has been investigated. The compositions of the reaction products formed at three temperatures have been determined
and the relationships between these analyses and observed differences in absorptivities by UV spectrometry are discussed.
Conclusions concerning the reaction mechanisms are based on compositional analysis and results of experiments using radioactive
or stable isotope labeled reagent. Double bonds in molecules which are not conjugated during the reaction retain the originalcis configuration. The double bond in the Δ12 position is the most susceptible to positional isomerization to form the conjugated
system. With the diene, this selectivity is small, while with the triene, the shifting of the Δ12 bond is the preponderant
initial reaction. Isotopic experiments yielded direct evidence for the postulated carbanion mechanism of reaction. An activated
methylene group is generally required for the formation of the carbanion. While the UV spectra of the reaction products formed
from methyl linolenate at 140 C showed no peak in the diene region, 34% conjugated diene-triene was present. The intact conjugated
systems can migrate when the reaction is sufficiently energentic to produce conjugated trienes with double bonds other than
the 10, 12, 14 system. The conjugation of triene is a stepwise reaction through the conjugated dienetriene.
This paper reports in part research submitted to satisfy thesis requirements for a Master’s Degree at Bradley University.
Bond Award paper. Award presented at the 43rd AOCS Fall Meeting, Minneapolis, October 1969.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
4.
K. J. Moulton R. E. Beal E. L. Griffin 《Journal of the American Oil Chemists' Society》1973,50(11):450-454
Reaction rates, linolenate/linoleate reaction selectivity,trans formation, and conjugated diene formation were determined for mixed commerical catalysts containing 0.5, 1, 2, 10, and 20
parts nickel catalyst (25% nickel) per 1000 parts copper chromite catalyst (ppt) and at catalyst concentrations in the oil
of 1.0, 0.5, and 0.25%. The rate of hydrogenation increased as the amount of nickel increased. Addition of 0.5, 1, and 2 ppt
nickel catalyst to copper chomite catalyst resulted in a small decrease in selectivity compared with straight copper chromite.
When soybean oil was hydrogenated with these mixed catalysts sufficiently to reduce linolenate to 0, iodine values were 102–108
compared to 109–112 for straight copper chromite and to less than 80 for straight nickel.
Presented at the AOCS Meeting, New Orleans April 1973.
ARS, USDA. 相似文献
5.
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
6.
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
7.
S. Koritala 《Journal of the American Oil Chemists' Society》1985,62(3):517-520
Soybean oil was hydrogenated with palladium acetylacetonate at 60–170 C, 150 psi hydrogen and 1–60 ppm palladium. The best
linolenate selectivity (KLe/KLo=3.5−3.7) was found at 80–120 C. At 120 C palladium acetylacetonate hydrogenated faster than the heterogeneous Pd-on-carbon
catalyst.Trans isomerization with the homogeneous catalyst was much higher compared to Pd-on-carbon catalyst. The low activity of the palladium
complex at low temperatures was improved with the addition of triethylaluminum. Among other metal acetylacetonates tested
only nickel and chromium were mildly active, whereas cobalt and copper were devoid of catalyst activity. 相似文献
8.
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
9.
Sambasivarao Koritala 《Journal of the American Oil Chemists' Society》1970,47(12):463-466
Hydrogenation of linolenate with copper chromite produced a large amount of conjugated diene and minor amounts of nonconjugatable
dienes. The double bonds in conjugated dienes and monoenes were scrambled all along the chain. This product distribution can
be explained if it is assumed that conjugation of the double bonds is followed by hydrogenation. In competitive hydrogenation,
fatty esters with conjugated double bonds were reduced preferentially over fatty esters with methylene-interrupted double
bonds. Isomerization of conjugated double bonds (geometric and positional) occurred more rapidly than reduction. Reduction
of conjugated double bonds in the presence of deuterium resulted in a majority of the products containing no deuterium. Most
of the added deuterium was incorporated into the unreacted material. Mechanisms are proposed to account for the products formed
during the hydrogenation of linolenate, linoleate and their isomers.
One of 10 papers to be published from the Symposium “Hydrogenation,” presented at the AOCS Meeting, New Orleans, April 1970.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
10.
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
11.
E. N. Frankel R. A. Awl J. P. Friedrich 《Journal of the American Oil Chemists' Society》1979,56(12):965-969
The use of Cr(CO)6 was investigated to convert polyunsaturated fats intocis unsaturated products. With methyl sorbate, the same order of selectivity for the formation ofcis-3-hexenoate was demonstrated for Cr(CO)6 as for the arene-Cr(CO)3 complexes. With conjugated fatty esters, the stereoselectivity of Cr(CO)6 toward thetrans, trans diene system was particularly high in acetone. However, this solvent was not suitable at elevated temperatures required to
hydrogenatecis, trans- andcis, cis-conjugated dienes (175 C) and nonconjugated soybean oil (200 C). Reaction parameters were analyzed statistically to optimize
hydrogenation of methyl sorbate and soybean oil. To achieve acceptable oxidative stability, it is necessary to reduce the
linolenate constituent of soybean oil below 1–3%. When this is done commercially with conventional heterogenous catalysts,
the hydrogenated products contain more than 15%trans unsaturation. By hydrogenating soybean oil with Cr(CO)6 (200 C, 500 psi H2, 1% catalyst in hexane solution), the product contains less than 3% each of linolenate andtrans unsaturation. Recycling of Cr(CO)6 catalyst by sublimation was carried through three hydrogenations of soybean oil, but, about 10% of the chromium was lost
in each cycle by decomposition. The hydrogenation mechanism of Cr(CO)6 is compared with that of arene-Cr(CO)3 complexes.
Presented in part at Seventh Conference on Catalysis in Organic Syntheses, Chicago, Illinois, June 5–7, 1978. 相似文献
12.
E. N. Frankel J. P. Friedrich T. R. Bessler W. F. Kwolek N. L. Holy 《Journal of the American Oil Chemists' Society》1980,57(10):349-354
New polymer-bound hydrogenation catalysts were made by complexing PdCl2, RhCl3·3H2O, or NiCl2 with anthranilic acid anchored to chloromethylated polystyrene. The Pd(II) and Ni(II) polymers were reduced to the corresponding
Pd(O) and Ni(O) catalysts with NaBH4. In the hydrogenation of methyl sorbate, these polymer catalysts were highly selective for the formation of methyl 2-hexenoate.
The diene to monoene selectivity decreased in the order: Pd(II), Pd(O), Rh(I), Ni(II), Ni(O). Kinetic studies support 1,2-reduction
of the Δ4 double bond of sorbate as the main path of hydrogenation. In the hydrogenation of soybean esters, the Pd(II) polymer
catalysts proved superior because they were more active than the Ni(II) polymers and produced lesstrans unsaturation than the Rh(I) polymers. Hydrogenation with Pd(II) polymers at 50~100 C and 50 to 100 psi H2 decreased the linolenate content below 3% and increasedtrans unsaturation to 10~26%. The linolenate to linoleate selectivity ranged from 1.6 to 3.2. Reaction parameters were analyzed
statistically to optimize hydrogenation. Recycling through 2 or 3 hydrogenations of soybean esters was demonstrated with the
Pd(II) polymers. In comparison with commercial Pd-on-alumina, the Pd(II) polymers were less active and as selective in the
hydrogenation of soybean esters but more selective in the hydrogenation of methyl sorbate.
Presented at ISF-AOCS Meeting, New York, April 1980. 相似文献
13.
Sambasivarao Koritala H. J. Dutton 《Journal of the American Oil Chemists' Society》1965,42(12):1150-1152
Selectivity of heterogeneous catalysts for hydrogenation of linolenate over linoleate is increased by the presence of certain
polar solvents. A ratio of specific reaction rate constants for linolenate to linoleate of 4 was obtained with a 5% palladium-on-alumina
catalyst when dimethyl formamide (DMF) was used as the solvent. This high selectivity of DMF was independent of temperature
and catalyst concentration. Other solvents that improved selectivity include furfural, acetonitrile, tetramethyl urea and
trimethyl phosphate.
Presented at AOCS meeting in Chicago, 1964.
A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, USDA. 相似文献
14.
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
15.
cis-bond-producing hydrogenation of polyunsaturates catalyzed by polymer-complexed Cr(CO)3 catalysts
R. A. Awl E. N. Frankel J. P. Friedrich E. H. Pryde 《Journal of the American Oil Chemists' Society》1978,55(7):577-582
cis-Bond-producing chromium carbonyl catalysts were prepared by complexing conventional or macroreticular, styrene-divinylbenzene
copolymers or cross-linked poly (vinyl benzoate) with Cr(CO)6. With one exception, these polymer-Cr(CO)3 catalysts were as selective as the corresponding homogeneous arene-Cr(CO)3 complexes for the formation ofcis-monoenes from methyl sorbate and from conjugated, polyunsaturated fatty esters in cyclohexane. Although several of the polymer
catalysts were very active when fresh, they all lost activity on recycling. They could not be recycled more than two times
before a marked decrease in activity occurred due to loss of Cr, as shown by elemental analysis and infrared absorption in
the recovered catalyst. Thermal analysis indicated instability of the polymer complexes at hydrogenation temperatures. 相似文献
16.
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
17.
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
18.
H. J. Dutton 《Journal of the American Oil Chemists' Society》1962,39(2):95-97
Equations for determining the ratio of hydrogenation rates for linolenate and linoleate acyl groups are derived from kinetic
theory. They are based upon the analysis for linolenate after absorption of 0.5 mole of hydrogen by an equal mixture of linoleate
and linolenate. This method finds routine application in the evaluation of hydrogenation catalysts for selectivity.
Presented at spring meeting, American Oil Chemists' Society, May 1–3, 1961, St. Louis, Mo.
This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department
of Agriculture. 相似文献
19.
C. R. Scholfield 《Journal of the American Oil Chemists' Society》1972,49(10):583-585
The products formed by hydrogenation of methylcis-9,trans-12- andtrans-9,trans-12-octadecadienoates with nickel and platinum catalysts have been compared with those from methyl esters of the naturally
occurring all-cis linoleate. Hydrogen uptake is slower for thetrans isomers. Much of the monoene consisted of esters with double bonds at the 9 and 12 positions with their original geometric
configurations. Monoenoic esters with double bonds at the 10 and 11 positions were predominatelytrans and apparently formed by conjugation before hydrogenation. Nickel produced more isomerization than platinum but less than
previously reported for copper. With both catalysts hydrogenation proceeded both directly and through conjugated intermediates,
in contrast to copper in which all hydrogenation is believed to follow conjugation.
Presented at the AOCS Meeting, Los Angeles, April 1972.
ARS, USDA. 相似文献
20.
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