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1.
The use of copper and cadmium oxides or soaps as catalysts for the hydrogenation of unsaturated fatty acids to unsaturated
fatty alcohols has been investigated. It is shown that copper soaps homogeneously activate hydrogen. When copper and cadmium
oxides are used as catalysts, they react with the acid under formation of a homogeneous soap solution. A continuous reaction
system for the preparation of unsaturated fatty alcohols by hydrogenation under the influence of copper and cadmium soaps
is described. 相似文献
2.
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
3.
Protection of dietary polyunsaturated fatty acids against microbial hydrogenation in ruminants 总被引:4,自引:0,他引:4
T. W. Scott L. J. Cook S. C. Mills 《Journal of the American Oil Chemists' Society》1971,48(7):358-364
Polyunsaturated fatty acids are normally hydrogenated by microorganisms in the rumen. Because of this hydrogenation ruminant
triglycerides contain very low proportions of polyunsaturated fatty acids. A new process is described whereby polyunsaturated
oil droplets are protected from ruminal hydrogenation by encapsulation with formaldehyde-treated protein. The formaldehyde-treated
protein resists breakdown in the rumen thereby protecting the fatty acids against microbial hydrogenation. When these protected
oils are fed to ruminants the formaldehydeprotein complex is hydrolyzed in the acidic conditions of the abomasum and the fatty
acids are absorbed from the small intestine. This results in substantial changes in the triglycerides of plasma, milk and
depot fats, in which the proportion of polyunsaturated fatty acids is increased from 2–5% to 20–30%. These effects are observed
in the plasma and milk within 24–48 hr of feeding while a longer period is necessary to alter the composition of sheep depot
fat. The implications of these findings are discussed in relation to human and ruminant nutrition. 相似文献
4.
5.
介绍了直链不饱和脂肪酸制备支链脂肪酸的研究现状,综述了脂肪酸异构机理,异构催化剂如白土催化剂、沸石催化剂,催化剂的筛选原则,着重讨论了各种常用沸石对于脂肪酸异构反应不同的影响以及现有的合成工艺。分析了脂肪酸的分离技术,包括精馏分离法、溶剂结晶法、尿素包结法、超临界流体萃取法的优缺点,指出沸石催化生产支链饱和脂肪酸的关键问题是需要解决混合脂肪酸作为原料反应的选择性问题,其相关的基础性工作,如更明确的反应机理和催化剂结构参数对反应的影响,仍是将来的研究方向。 相似文献
6.
E. H. Pryde 《Journal of the American Oil Chemists' Society》1984,61(2):419-425
When hydroformylation of unsaturated fatty materials is done with rhodium-triphenyl phosphine (or phosphite) catalysts, a
number of advantages become apparent compared to cobalt carbonyl-catalyzed reactions. With rhodium, the reaction can be carried
out (a) at pressures as low as 200 psi, (b) at each double bond location in a polyunsaturated fatty acid, and (c) in high
yield and conversion. Solubilized catalyst can be recovered from distillation residue and readsorbed on spent catalyst support
by thermal treatment in a rotary kiln. The reconstituted catalyst is more active than the original catalyst and can be recycled
indefinitely at a relatively low cost. Recently developed supports for “homogeneous” catalysis may make catalyst recovery
even more effective. Acetalation, oxidation with air to polycarboxylic acids and catalytic hydrogenation to hydroxymethyl
compounds can be done easily and in high yield on mono-, di- and triformyl derivatives alike. Other reactions investigated
for monoformyl fatty esters include reductive amination to form aminomethyl derivatives and Tollen’s condensation with formaldehyde
to form geminal,bis-hydroxymethyl compounds. although the Northern Center has carried out some basic investigations on the hydroformylation reaction
and on the chemistry of the hydroformylated products, there is a great deal more that can be done with regard to synthesis
of new compounds and development of new applications. 相似文献
7.
8.
Charles G. Goebel 《Journal of the American Oil Chemists' Society》1947,24(3):65-68
Summary A method is proposed for the preparation of polybasic fat acids or “dimer” acids directly from fatty acids which is readily
adaptable to commercial use. The presence of moisture maintained in the reaction vessel by steam pressure substantially prevents
decomposition and decarboxylation of the fatty acids. By this method a larger percentage of dibasic acids, as compared to
tribasic acids, is produced than by the previously described methods. The method of high temperature polymerization of fatty
acids in the presence of moisture is also used to remove polyunsaturated fatty acids from commercial oleic acid.
Presented at 20th fall meeting, American Oil Chemists’ Society, Chicago, Ill., Oct. 30–Nov. 1, 1946. 相似文献
9.
H. H. Hofstetter N. Sen R. T. Holman 《Journal of the American Oil Chemists' Society》1965,42(6):537-540
The equivalent chain length (ECL) has been determined on 79 methyl esters of unsaturated fatty acids and on 7 ethyl esters
by gas chromatography. Ethylene glycol succinate (EGS), diethylene glycol succinate, β-cyclodextrin acetate and Apiezon L
were chosen as the liquid phases to be used. For methyl esters of mono- and polyenoic acids, the differences between ECL on
EGS and ECL on Apiezon L approximate 0.84 per double bond. For positional isomers, the ECL on both EGS and Apiezon L are usually
greater for the isomer having the longer proximal end of the molecule (smallest ω value). In these terms a triple bond is
approximately equal to three double bonds. Esters of nonconjugated dienoic and trienoic acids of the same chain length are
not separable on Apiezon L if their proximal structures are the same. This also applies to tetraenoic and pentaenoic acids
of the same chain length and the same proximal structure. Conjugation of double bonds, either with the ester carbonyl group
or with themselves, yields ECL values on Apiezon L greater than the number of carbon atoms in the acid. Monounsaturated and
nonconjugated polyunsaturated esters have ECL values on Apiezon L lower than the number of carbon atoms of the acid. The ECL
values of ethyl esters of 18 and 20 carbon acids are greater than the corresponding methyl esters on Apiezon L.
Presented at the Chicago meeting of the American Oil Chemists’ Society, Oct. 13, 1964. 相似文献
10.
A study was made of the influence of semisynthetic diets of low and high unsaturation on the fatty acid composition and desaturation-chain
elongation enzymatic activity of the liver microsomal fractions of male Sprague-Dawley rats of different ages. Groups of rats
were fed 5 or 20% coconut oil (CO), or a 5 or 20% mixture of corn and menhaden oils (3∶7) (CME) from weaning to 100 wk of
age. Growth rate and food consumption were measured during this period in which animals were sacrificed at 36, 57, 77 and
100 wk of age. Both the level and composition of the dietary fat supplements produced marked effects on the fatty acid composition
of the liver microsomal lipids. In general, the fatty acid composition of the microsomal fractions reflected that of the dietary
fat and was more unsaturated with the higher level of fat fed. The rate of conversion of linoleic to arachidonic acid in assays
performed in vitro with liver microsomal preparations from animals of the different groups also showed marked differences.
The 6-desaturase-chain elongation activity was higher in the 5% than 20% group and corresponded to the essential fatty acid
(EFA) status of the animals in these groups as represented by the triene-tetraene ratio of the microsomal lipid. The relationship
of the 6-desaturase activity to fatty acid composition of the microsomal lipid indicated that if varied directly with the
level of 20∶3ω9, 18∶1 and 16∶1 and was inhibited by arachidonic acid. The activity of the 6-desaturase enzyme system was lowest
in the liver microsomal fraction obtained from the animals fed the CME diets and appeared to be suppressed by the high levels
of 20∶5 and 22∶6 that accumulated in the microsomal lipid. Accordingly, the levels of arachidonic acid were lower in the microsomal
lipid of these groups than those of the corresponding CO groups in spite of a greater abundance of linoleic acid in the diet.
The data suggest that the activity of the 6-desaturase-chain elongation system is regulated by the fatty acid composition
of the microsomal lipid as influenced by the composition of the dietary fat. 相似文献
11.
Three new 10-hydroxy fatty acids, all optically active, have been prepared by the anaerobic microbiological hydration of acis-9 double bond. Substrates that formed these new hydroxy fatty acids are linoleic, linolenic, and ricinoleic acids. The hydroxyl
group has the D configuration and the methyl esters are levorotatory. Infrared, mass spectral, specific rotation and ultraviolet
data on these compounds were determined. There was no migration of the unreated double bonds at C12 and C15 in linoleic or linolenic acids. The presence of a double bond in the 10-hydroxy fatty acids significantly increased the optical
rotation of the methyl esters. The hydratase enzyme showed unusual specificity among Δ9 unsaturated acids. While it hydrates methylene interrupted and hydroxy unsaturated acids, it failed to hydrate either 9-decenoic,
12,13-epoxy- or 12-keto-cis-9-octadecenoic acids or sterculic acid.
Presented at the AOCS Meeting, San Francisco, April 1969.
No. Marketing and Nutrition Res. Div., ARS, USDA. 相似文献
12.
Frits van der Klis Marinus H. van den Hoorn Rolf Blaauw Jacco van Haveren Daan S. van Es 《European Journal of Lipid Science and Technology》2011,113(5):562-571
Long‐chain internal olefins were prepared by silver(II)‐catalyzed oxidative decarboxylation of unsaturated fatty acids by sodium peroxydisulfate. Similar to saturated carboxylic acids, 1‐alkenes were the major decarboxylation product in the additional presence of copper(II), whereas in the absence of copper(II) alkanes were predominantly formed. In both cases, the internal unsaturation of the fatty acids remained largely intact, although the moderate yields indicated that side reactions occurred to a significant extent. The simple procedure makes this multistep one‐pot reaction useful for the synthesis of a variety of internally unsaturated hydrocarbons. The purified products, almost all of which are prepared for the first time, may serve as reference compounds for studies on the heterogeneously catalyzed decarboxylation of triglycerides and fatty acids in the absence of hydrogen. Practical applications: The products of the chemistry described in this contribution, i.e., unsaturated long‐chain hydrocarbons, provide bio‐based building blocks for further chemical modification toward products which may be applied as (bio)fuels, lubricants, solvents, and polymeric materials. 相似文献
13.
Martin aus dem Kahmen Hans J. Schfer 《European Journal of Lipid Science and Technology》1998,100(6):227-235
Diels-Alder reactions with methyl conjuenate ( 2 ) at room temperature, with methyl E-12-oxo-10-octadecenoate ( 11 ) as dienophile and radical cation catalyzed cycloadditions of 2 are described. 2 is prepared from methyl linoleate by base catalyzed isomerization with sodium dimethylsulfoxide in 90% yield. It undergoes readily Diels-Alder reactions at room temperature in the presence of 1–1.8 equivalents of a Lewis acid and catalytic amounts of iodine to form cycloadducts in 55–90% yield. At 140°C 2 reacts with dimethyl maleate and dimethyl acetylenedicarboxylate to cycloadducts in 86% and 73% yield, respectively. Methyl E-12-oxo-10-octadecenoate ( 11 ) can be combined in a Diels-Alder reaction with the dienes 2-(trimethylsilyloxy)-1,3-butadiene and 2,3-dimethylbutadiene in 69% and 86% yield, respectively. By way of radical cation catalysis 2 undergoes [4+2]-cycloadditions with dienes in high yield. 相似文献
14.
Trans unsaturated fatty acids in bacteria 总被引:1,自引:0,他引:1
The occurrence oftrans unsaturated fatty acids as by-products of fatty acid transformations carried out by the obligate anaerobic ruminal microflora
has been well known for a long time. In recent years, fatty acids withtrans configurations also have been detected in the membrane lipids of various aerobic bacteria. Besides several psychrophilic
organisms, bacteria-degrading pollutants, such asPseudomonas putida, are able to synthesize these compoundsde novo. In contrast to thetrans fatty acids formed by rumen bacteria, the membrane constituents of aerobic bacteria are synthesized by a direct isomerization
of the complementarycis configuration of the double bond without a shift of the position. This system of isomerization is located in the cytoplasmic
membrane. The conversion ofcis unsaturated fatty acids totrans changes the membrane fluidity in response to environmental stimuli, particularly where growth is inhibited due to the presence
of high concentrations of toxic substances. Under these conditions, lipid synthesis also stops so that the cells are not able
to modify their membrane fluidity by any other mechanism. 相似文献
15.
Bottino NR 《Lipids》1967,2(2):155-160
Rats fed a fat-free diet from weaning were contined on that diet alone or supplemented with methyl linoleate, methyl linoleate
plus a mixture of antibiotics, or methyl arachidonate.
Dietary linoleate and arachidonate reduced the concentration of octadecenoic acid and increased that of stearic acid in the
mucosa and luminal lipids. This effect was prevented in the mucosa but not in the intestinal contents by antibiotic supplementation
of the linoleate diet.
Evidence for the conversion of linoleic into eicosatetraenoic acid was found in both mucosa and luminal lipids. The conversion
was impaired by the addition of antibiotics to the diet.
Linoleate feeding combined with antibiotic addition provided evidence for the intestinal hydrogenation of dietary linoleic
into either octadecenoic or stearic acids by separate routes, the latter being impaired by antibiotic ingestion.
The ingestion of methyl linoleate or arachidonate modified only slightly the fecal fatty acid pattern of rats previously on
a fat-free diet. 相似文献
16.
Liquid-phase catalytic oxidation of unsaturated fatty acids 总被引:8,自引:0,他引:8
Liquid-phase catalytic oxidation of oleic acid with hydrogen peroxide in the presence of various transition metal/metal oxide
catalysts was studied in a batch autoclave reactor. Azelaic and pelargonic acids are the major reaction products. Tungsten
and tantalum and their oxides in supported and unsupported forms were used as catalysts. Alumina pellets and Kieselguhr powder
were used as supports for the catalysts. Tungsten, tantalum, molybdenum, zirconium, and niobium were also examined as catalysts.
Tertiary butanol was used as solvent. Experimental results concluded that tungsten and tungstic oxide are more suitable catalysts
in terms of their activity and selectivity. The rate of reaction observed in the case of supported catalysts appears to be
comparable or superior to that of unsupported catalysts. In pure form, tungsten, tantalum, and molybdenum showed strong catalytic
activity in the oxidation reaction; however, except for tantalum the other two were determined to be economically unfeasible.
Zirconium and niobium showed very little catalytic activity. Based on the experimental observations, tungstic oxide supported
on silica is the most suitable catalyst for the oxidation of oleic acid with 85% of the starting oleic acid converted to the
oxidation products in 60 min of reaction with high selectivity for azelaic acid. 相似文献
17.
Double bond oxidation of unsaturated fatty acids 总被引:1,自引:0,他引:1
B. Zaldman A. Kisilev Y. Sasson N. Garti 《Journal of the American Oil Chemists' Society》1988,65(4):611-615
Different oxidizing agents for performing the cleavage oxidation of the double bond of the unsaturated fatty acids are presented,
and their economic performance is analyzed. Ozone and sodium hypochlorite are the most commercially efficient oxidants.
Laboratory work for the oxidation of oleic acid to azelaic and pelargonic acids using hypochlorite as oxidant is described.
The advantages of working in an emulsion system and using RuCl3 as a catalyst are discussed, and a possible mechanism of the reaction is presented. A flow sheet for an industrial process
based on this concept is proposed. A simulation of a plant using this technology is made by a computerized model, and the
economic parameters obtained permit us to conclude that the sodium hypochlorite can be an interesting reagent for industrial
oxidations of double bonds in fatty acids. 相似文献
18.
F. D. Gunstone 《Journal of the American Oil Chemists' Society》1984,61(2):441-447
Oxygen reacts readily with unsaturated fatty acids so that every time these compounds are handled there is a danger they will
become contaminated with oxidation products. The products formed first are allylic hydroperoxides which are labile molecules
that change rapidly to other compounds, some of which are highly flavorous. Sometimes these changes are desirable and may
be promoted: frequently they are not and have to be inhibited. Instrumental procedures recently introduced—especially separation
by high performance liquid chromatography and identification by1H and13C nuclear magnetic resonance spectroscopy—have led to a renewed interest in this subject. For the nonenzymic processes of
autoxidation and photooxygenation we now have a better understanding of the routes leading to the first-formed allylic hydroperoxides
and an improved appreciation of the structure of further oxidation products including dihydroperoxides and hydroperoxides
which also contain one or more cyclic peroxide units. Direct chemical routes to several of these compounds have also been
developed. Oxidation of linoleic acid by plant-derived lipoxygenases gives diene hydroperoxides similar to those produced
by autoxidation, except that the former are optically active and the latter racemic. Enzymic oxidation of arachidonic acid
and certain related C20 acids in animal systems produces a wide variety of prostaglandins, physiological properties. These compounds have been described
as “tomorrow’s drugs”. 相似文献
19.
The rates of autoxidation of oleic acid, ethyl oleate, linoleic acid, 10,12-linoleic acid, ethyl linoleate, trilinolein, pentaerythritol linoleate, dipentaerythritol linoleate, elaidolinolenic acid, linolenic acid, ethyl linolenate, trilinolenin, and methyl arachidonate have been studied by oxygen uptake in a Warburg respirometer and the results are compared with the rates of enzymatic oxidation of lipoxidase substrates. The increase in the number of double bonds in a fatty acid by one increases the rate of oxidation of the fatty acid or its esters by at least a factor or two. Earlier findings that acids oxidize more rapidly than their esters have been confirmed. The initial rates of lipoxidase oxidation of ethyl linoleate, ethyl linolenate, and methyl arachidonate were found to be essentially the same. 相似文献
20.
Separation of saturated/unsaturated fatty acids 总被引:3,自引:0,他引:3
G. Haraldsson 《Journal of the American Oil Chemists' Society》1984,61(2):219-222
Fatty acid mixtures can be separated into one fraction rich in saturated fatty acids and the other rich in unsaturated acids.
Since saturated fatty acids have a higher melting point than unsaturated, liquid mixture to be fractionated is cooled to a
temperature at which the larger part of the saturated acids crystallize, while the greater part of unsaturated acids remain
in liquid form. Different industrial methods to separate the two phases are described. The oldest and simplest method is slowly
to cool and crystallize the mixture in shallow pans to form cakes which then are pressed in presses of different design. By
applying high pressure, the liquid olein is thus squeezed out from the cake, leaving the stearin fraction behind. A new process
to separate the phases is to mix an aqueous solution, containing a wetting agent, with the crystallized fatty acid mixture.
The stearin crystals are thus wetted and transferred into the aqueous phase, which then can be separated from the olein phase
in a centrifuge. The stearin/aqueous suspension is heated to melt the stearin, which can then be separated in a second centrifuge.
Other methods to improve phase separation use organic solvents, among which are methanol, acetone, methyl formate and propane.
In the solvent fraction process, the miscella has to be cooled to a lower temperature than in the aforementioned methods,
due to the solubility effect of the solvents. The solvents are removed by distillation from the fraction. Typical operation
results with different types of raw materials are given. The advantages and disadvantages of the different methods are discussed. 相似文献