Autoxidation Of Methyl Oleate Research Articles

INHIBITORY EFFICIENCY AND PHYSICOCHEMICAL PROPERTIES OF LIPIDS FROM LEAVES AND JUICE OF ALOE ARBORESCENS Mill.

The composition of lipids isolated from leaves and juice of A. arborescens (7 years ago) and the inhibitory efficiency of lipids from leaves of A. arborescens were studied. The phospholipid (PL) fractions were divided by means of TLC method. The quantitative proportion of PL fractions was determined by spectrophotometrically. The more substantial differences in the composition of PL from leaves and juice of A. arcorescens are revealed in the proportion of the more poorly oxidizable fractions of PL. The more low relative content of PL in the total lipid composition from leaves compared with than in lipids from juice, and shares of sterols are the same for lipids from leaves and juice cause 16% diminution of the molar ratio of [sterols]/[PL] in lipids from juice of A. arborescens. Lipids from leaves are known to characterize the high inhibitory efficiency that is demonstrated by model of the low temperature autoxidation of methyl oleate in the thin layer. Using UV-spectroscopy and the mathematic analysis of spectra by Gauss method the presence of the biologically active substances which contain in lipids was analysed. There are only flavonoids in the chloroform solution of lipids from juice and flavonoids and carotenoids in the small quantity in the chloroform solution of lipids from the leaves of A. arborescens.

A review on the role of allylic and bis allylic positions in biodiesel fuel stability from reported lipid sources

ABSTRACTReported procedures of estimating allylic position equivalent (APE), bis allylic position equivalent (BAPE) and oxidizability is applied to reported work on autoxidation of methyl oleate with addition of methyl linoleate at 20 and 50 °C. Plot of reported peroxide value (PV) versus estimated oxidizability of autoxidation reactions indicates the effect of APE in rapidly increasing PV of neat methyl oleate at 50 °C. Plot of estimated oxidizablity versus estimated APE and BAPE of reported unsaturated fatty acid methyl esters (FAME) from four lipid sources results in novel insights of a linear relationship of oxidizability with BAPE and non-linear relationship with APE. Limitations of iodine value (IV) as an oxidation stability standard for biodiesel is highlighted by comparing with reported oxidation stability measurements of FAME from two lipid sources. Comments on thermal stability of biodiesel and antioxidants reveals challenges of preparing robust rugged antioxidants for oxidative as well as thermal stability.

環境に優しい潤滑油 オリーブ油とオレイン酸メチル分子内官能基の潤滑性に及ぼす影響

The lubrication characteristics of the olive oils, which are used as biodegradable lubricants, on the steel ball were examined on the viewpoint of their growing area and quality of the olive oil. The discoloration of virgin olive oil and the friction face and/or the friction force of the steel ball were found to be dependent on their growing area as well as pure olive oil. Property of the constituent metal constituents of steel ball on the air oxidation of methyl ester of oleic acid, which is major constituent fatty acid of olive oil and the lubrication characteristics of the resulting oxidation products, were investigated. The autoxidation of methyl oleate under the existence of each acetylacetonatos of Cr, Mn, Fe, Ni, Cu, and V was carried out by blowing dry air at 80°C. All the metal salts except V facilitated the oxidation. The metals employed affect the yields and the types of the products, i.e., hydroperoxide, hydroxide and epoxide whom the functional group exists for the center location of molecular chain. Friction test for ball bearing was conducted by using each oxidation product and parent methyl oleate. The surface of the steel ball was the abrasive wear condition by hydroperoxide. The hydroxide gave excellent lubrication characteristics by hydroxy group adsorbed on the surface of steel ball. Epoxide increased the coefficient of friction. Methyl linoleate, having two double bonds, provided the flatted frictional surface at the ball bearing, but it is easy to be oxidized. To sum up the major characteristics of the autoxidation products which affect friction surface of steel ball, the function groups of center position in molecular chain of methyl oleate are of most significance. It was found that double bond and hydroxyl function of α-position of double bond are effective under the boundary lubrication.

On the kinetics of the autoxidation of fats. II. Monounsaturated substrates

AbstractThe autoxidation of methyl oleate and oleic acid shows some differences as compared to the autoxidation of linoleate,e.g., the formation of water at an early stage. Linearization of experimental data on the autoxidation to high oxidation degrees of methyl oleate and other monounsaturated substrates shows that the rate equations previously derived for methyl linoleate in the range of 1–25% oxidation are valid, provided the correct expression for the remaining unreacted substrate is used. With monounsaturated substrates, part of the oxygen is consumed by a secondary oxidation reaction almost from the beginning, and only a certain constant fraction α of the total O2 consumption is consumed in hydroperoxide formation. The fraction α is different for methyl oleate, oleyl alcohol, oleic acid andcis 9‐octadecene, but the rate constant for the hydroperoxide formation is the same for all of them when experimental conditions are the same. The main difference between oleate and linoleate autoxidation is the much faster decomposition of the oleate hydroperoxides relative to their slow formation.

Effects of Metal (periodic group VI) Hexacarbonyls on the Autoxidation of Methyl Oleate and the Decomposition of Methyl Oleate Hydroperoxide

To compare the effects of various metals (periodic group VI) on the autoxidation of methyl oleate and the decomposition of methyl oleate hydroperoxide in methyl oleate, the substrates were kept with metal carbonyls [Mo (CO) 6, Cr (CO) 6 and W (CO) 6] at 80°C.The effects of the catalysts were investigated by observing the changes in peroxide value, iodine value, saponification value, refractive index, molecular weight, and trans isomer content. The identification of autoxidation products of methyl oleate and decomposition products of methyl oleate hydroperoxide were carried out by gas chromatography of trimethylsilyl ether derivatives.Mo (CO) 6 showed marked effect on the autoxidation of methyl oleate and the decomposition of methyl oleate hydroperoxide. The products were found as methyl cis-epoxyoctadecanoate and methyl hydroxyoctadecenoate, which were produced by intermolecular reaction among methyl oleate and methyl oleate hydroperoxide. Moreover, methyl hydroxyepoxyoctadecanoate was also produced by intramolecular reaction of methyl oleate hydroperoxide itself.Cr (CO) 6 showed more marked effect than Mo (CO) 6. The autoxidized products of methyl oleate were identified as methyl trans-epoxyoctadecanoate, methyl cis-epoxyoctadecanoate, methyl hydroxyoctadecenoate and methyl oxooctadecenoate, but methyl hydroxyepoxyoctadecanoate was not produced. Methyl oxooctadecenoate and methyl hydroxyoctadecenoate were produced by decomposition of methyl oleate hydroperoxide in the presence of Cr (CO) 6, but W (CO) 6 showed almost no effects.

Stereochemistry of olefin and fatty acid oxidation. Part 3. The allylic hydroperoxides from the autoxidation of methyl oleate

Methods have been developed, using 13C n.m.r. spectroscopy and mass spectrometry, for the analysis of all eight cis and trans allylic 8-, 9-, 10-, and 11-hydroperoxides formed on autoxidation of methyl oleate.

Effects of Metal Acetylacetonates on the Autoxidation of Methyl Oleate and the Decomposition of Hydroperoxide of Methyl Oleate

The experiments on the autoxidation of methyl oleate (OM) and the decomposition of by droperoxide of methyl oleate (OMH) in OM were carried out in the presence of acetyl acetonates (VO, MoO2, Co and Cr) at 80°C. The effects of the catalysts were investigated by observing the changes in peroxide value, iodine value, saponification value, refractive index, molecular weight and content of trans isomer. The identification of autoxidation products of OM and decomposition products of OMH were carried out by gas chromatography of trimethylsilyl ether derivatives.VO (acac) 2 inhibited the autoxidation of OM, but had a remarkable effect for the decomposition of OMH. The main decomposition product was the methyl hydroxyepoxyoctadecanoate (HE), which was produced by the intramolecular reaction of OMH. MoO2 (acac) 2 had remarkable effects for the autoxidation of OM and the decomposition of OMH. The both products were the cis methyl epoxyoctadecanoate (CE), methyl hydroxyoctadecenoate (HO) and HE. The CE and HO seemed to be produced by the intermolecular reaction of OMH and OM and by the intramolecular reaction of OMH in the case of HE.Co (acac) 3 and Cr (acac) 3 had remarkable effects which were different from the acetylacetonates of VO and MoO2 for oxidation of OM and decomposition of OMH. The epoxide produced by autoxidation of OM was a trans-form.

Lipid oxidation. Part V. Effect of copper on the autoxidation of methyl oleate

AbstractMethyl oleate was oxidized at 60°C at free access of air in presence of varying amounts of copper(II)‐chloride. Changes of hydroperoxides followed equation (V):magnified image.The relationships between the two reaction rate constants and the concentration of copper(I1)ions are best expressed by hyperbolic equations (VII) and VIII, respectively:magnified image.The relation between the concentration of copper and the time necessary to attain the maximum rate of increase of the hydroperoxide content was hyperbolic as well. The rate of the hydroperoxide formation increases thus with the increasing content of copper chloride but the rate of hydroperoxide decomposition becomes still more rapid at the same time so that the accumulation of hydroperoxides is inhibited in case of extremely high concentrations of copper.

ChemInform Abstract: ALLYLIC HYDROPEROXIDES FROM THE AUTOXIDATION OF METHYL OLEATE

AbstractDie Autoxidation.

Allylic hydroperoxides from the autoxidation of methyl oleate

Methods have been developed, using 13C n.m.r. and mass spectrometry, for the analysis of all eight cis and trans allylic 8-, 9-, 10-, and 11-hydroperoxides formed on autoxidation of methyl oleate.

Autoxidation of fatty materials in emulsion. III. Application of GLC and TLC to studies of the histidine‐catalyzed autoxidation of methyl oleate

AbstractMethyl oleate, emulsified with sodium dodecyl‐sulfate, was extensively oxidized, and the amount of oleate which was reacted was determined by GLC using methyl palmitate as an internal standard. The effects of histidine, iron, and histidine plus iron were compare with the uncatalyzed reaction in the presence and absence of ultraviolet light. Results in the absence of ultraviolet light confirmed previous findings that histidine and histidine plus iron are prooxidants at the concentration studied. In the presence of ultraviolet light the rate of oleate oxidation was about 100× faster than that of the nonirradiated reaction, and the effect of the catalysts was almost negligible. The principal products, determined by GLC and TLC, were epoxide and α,β‐unsaturated carbonyl. Hydroperoxy, hydroxy, acid and aldehyde compounds were also present. Epoxy stearate, determined by GLC, compared favorably with epoxy stearate as determined by use of the Durbetaki method.

Effect of Metal Chlorides on the Autoxidation of Methyl Oleate

Effect of metal chlorides on the autoxidation of methyl oleate was investigated by observing the changes in peroxide value, iodine value, saponification value and refractive index at 80°C. VCl4 and PdCl2 accelerate markedly the peroxide-decomposition, while BiCl3 and ZrCl4 showed less effect, and.AlC3 and SiCl4 showed no effect. In the addition of MoCl5, TiCl4 or WCl5 the changes in peroxide value, saponification value, acid value and refractive index wereless but decrease in the iodine value was great, and the oxidation reaction in the presence of such chloride seemed to occur by another mechanism rather than usual. SbCl5, GeCl4, InCl3 and SnCl4 inhibited the autoxidation.

Effect of Metals on the Autoxidation of Methyl Oleate

Effect of Metals on the Autoxidation of Methyl Oleate

Determination of Structure and Analysis of the Hydroperoxide Isomers of Autoxidized Methyl Oleate

AbstractA procedure is described demonstrating the formation of four hydroperoxide isomers in the autoxidation of methyl oleate in accordance with the free radical chain reaction concept of autoxidation. Experimental proof is also given for the location of the hydroperoxide group in the α‐position relative to the double bonds. New methodology is reported in the use of catalytic reduction with the Lindlar Catalyst for the quantitative estimation of peroxides. The quasi‐six membered ring theory of oxidation as applied to the atmospheric oxidation of fats is shown to have no factual basis.

A study of the volatile compounds produced by the autoxidation of methyl oleate, oleic acid, and cis‐9‐octadecene

SummaryMethyl oleate, oleic acid, and cis‐9‐octadecene were oxidized at 80° with a stream of air, and the volatile decomposition products were collected in dry ice traps. The volatile material consisted of an aqueous fraction and water‐soluble substances, an oil fraction, and a crystalline product. The substances in the aqueous fractions were characterized as formic and acetic acid, and their formation was studied during the autoxidation of the various substrates up to 21 days. The crystalline material was purified, and its properties were examined. The purified crystals showed chemical and infrared properties very similar to a sample of synthesized bis‐(hydroxyheptyl) peroxide. Formic and acetic acid were also shown to be produced during the decomposition of hydroxyalkyl peroxides.

Reactions of fatty materials with oxygen. XX. Recent developments in the autoxidation of methyl oleate and other monounsaturated fatty materials

SummarySome significant developments since 1947 in the autoxidation of methyl oleate and other monounsaturated fatty materials have been reviewed and critically evaluated. Subjects discussed are preparation and characterization of hydroperoxides, and mechanism, kinetics, and secondary products of autoxidation. Major developments in the field have resulted largely from the use of newer instruments (polarograph, infrared spectrophotometer) and separation techniques (urea complexes, molecular distillation, countercurrent distribution).Direct experimental evidence is now available which demonstrates that a) hydroperoxides are the predominating, but not the exclusive, primary products of autoxidation; b) the hydroperoxides obtained from methyl oleate are mostly, if not entirely,trans; c) substantially all the methyl oleate undergoes single attack in the chain before any significant amount of multiple attack occurs, and d) α,β‐unsaturated carbonyl compounds are among the most important secondary products of autoxidation.

Reactions of fatty materials with oxygen. XVI. Relation of hydroperoxide and chemical peroxide content to total oxygen absorbed in autoxidation of methyl oleate

SummaryMethyl oleate has been autoxidized at 100°, 80°, and 60° in the Barcroft‐Warburg apparatus. Samples have been analyzed for total peroxide by the iodometric method and for hydroperoxide by the polarographic method. These peroxide values have been compared with each other and with total oxygen absorbed.The relation of chemical peroxide (yc) to oxygen uptake (x) is expressed by yc=1.09x0.936. This equation is equally valid at the three temperatures for the first 150 millimoles (15%) of oxygen absorbed per mole of methyl oleate.Similarly, the hydroperoxide content (yh) for the first 150 millimoles of oxygen absorbed at 80° and 100° is given by the equation yh=1.02x0.936.The ratio of hydroperoxide to chemically determined peroxide was, on the whole, constant throughout the entire range of oxidation (15–300 millimoles of oxygen absorbed per mole), and averaged about 95%.It has been shown unequivocally that the major portion of the peroxides formed in the autoxidation of methyl oleate are hydroperoxides, confirming conclusions of recent investigators. A small but significant amount of non‐hydroperoxidic peroxide appears to be formed concurrently.

Reactions of fatty materials with oxygen. VIII. Cis‐trans isomerization during autoxidation of methyl oleate

SummaryMethyl oleate irradiated with ultra‐violet light has been autoxidized at 35° and the reaction has been followed by means of the infrared spectrophotometer. During the extremely early stages of autoxidation and continuing up to at least 700 hours, a cis‐trans isomerization induced by oxygen is one of the reactions which occurs.The data suggest that most, if not all, of the peroxides produced during the autoxidation of methyl oleate, at least up to 300 hours, are trans peroxides and not methyl oleate peroxides, as had been previously supposed. A mechanism for the formation of trans peroxides from allylic free radicals is proposed.Mechanisms are also proposed for the formation of non‐peroxidic trans materials during autoxidation. These could explain the formation of trans‐9,10‐epoxystearic acid and high melting 9,10‐dihydroxystearic acid from autoxidizing oleic acid.

Autoxidation of methyl oleate, methyl stearolate, and methyl 9,10‐dieuteroöleate

SummaryA comparative study of the autoxidation of methyl oleate, methyl 9,10‐dideuteroöleate, methyl stearolate, and stearolic acid has re‐emphasized the complexity of the autoxidation phenomenon. The autoxidation of the acetylenic compounds indicates the importance of peroxidation of the active methylene group as compared to the addition of oxygen at the unsaturated linkages. The importance of olefinic hydrogens and the role of the double bond with respect to the induction periods and possible addition reactions has been brought out by the studies on the autoxidation of the deuteroöleate. Consequently it appears that during autoxidation of methyl oleate, oxidative attack is initiated at the olefinic position and then at α‐methylenic position and that water formation occurs shortly thereafter. At least some of the hydrogen of the water formed during autoxidation comes from the olefinic hydrogens.It appears that most of the non‐aqueous volatile cleavage products arising from a rupture of a carbon to carbon bond are peroxidic in character. The nature of these volatile peroxides appears different from several commercially available organic peroxides since they are capable of oxidizing methyl oleate in a manner to yield the high melting form of dihydroxystearic acid whereas peracids and some peroxides under similar conditions give only the low melting isomer.

461. The autoxidation of methyl oleate and linoleate, and the decomposition of the oxidation products : a theoretical discussion

461. The autoxidation of methyl oleate and linoleate, and the decomposition of the oxidation products : a theoretical discussion