Structures of ozonolysis products of methyl oleate obtained in a carboxylic acid medium

High-performance liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectrometry (NMR) were applied to the analysis of organic peroxide mixtures, which were labile and tended to decompose during analysis. The ozonolysis reaction of methyl oleate gives a peroxide mixture, and, finally, mono- and dibasic acids are obtained by subsequent oxidation. In this study, methyl oleate was ozonized in a nonanoic acid medium, one of the final reaction products. The reaction products were directly analyzed by LC-MS equipped with a frit-fast atom bombardment interface. The molecular ion peak of each peroxide was clearly observed, and its molecular weight was readily determined. On the other hand, each peroxide was fractionated by high-performance liquid chromatography and submitted to structural analysis by NMR. Both results indicated that the reaction products include four peroxidic species: 1,2,4-trioxolaneI, peroxide oligomerII, 1-acyloxyalkyl-1-hydroperoxideIII, and 1-acyloxyalkyl-1′-hydroxyalkyl peroxideIV, as well as an aldehydeV. Ozonolysis of methyl oleate in the absence of solvent produces mainlyI, while that in the presence of a carboxylic acid solvent characteristically produces mainlyIII andIV derived from the solvent.Bis(1-acyloxyalkyl-1-alkyl) peroxide, which was reported previously as a ozonolysis product of methyl oleate, was concluded to beIV in this study. This work was presented at the 31th Annual Meeting of the Japan Oil Chemists’ Society, 1992, Tokyo, Japan.     

One step hydroxybromination of fatty acid derivatives

Hydroxybromination of methyl oleate, oleic acid and new sunflower oil (high oleic), in an acetone/water mixture by a one step reaction using N‐bromosuccinimide, was studied. The yield of bromohydrin products from oleic acid, methyl oleate and sunflower oil were 90%, 78% and 40%, respectively. Reaction products were analyzed by ¹H and ¹³C nuclear magnetic resonance spectroscopy, infrared spectroscopy, gas chromatography, and mass spectrometry. The hydrobromide derivative of new sunflower oil was acrylated and polymerized to a new polymer.     

A comparison of participating solvents during ozonization

Sixteen different participating solvents and certain combinations thereof were evaluated for their effects on the conversion of methyl oleate to carbonyl compounds by ozonolysis. Depending upon the alcohol or carboxylic acid used as a single solvent, chemical reduction with zinc and acetic acid gave yields of 70–100%; catalytic hydrogenation with 10% Pd/C, 62–84%. When equimolar mixtures of an acid and a primary, unhindered alcohol were used, catalytic hydrogenation gave yields of 94–98%. In preparative scale experiments, catalytic hydrogenation gave 98% yields of methyl azelaaldehydate in the representative solvent combinations of 2-methoxyethanol/acetic acid and 1-butanol/propionic acid. When anhydrous calcium sulfate was used as a drying agent for aldehyde/alcohol solutions significant acetal was formed in the absence of other catalysts. Presented in part at the AOCS Meeting, New Orleans, La., April, 1964. A laboratory of the No. Utiliz. Res. and Dev. Div., ARS, USDA.     

Reactions of fatty materials with oxygen. XVIII. Catalytic hydrogenation of autoxidized methyl oleate and oleic acid. Preparation of monohydroxystearic acids

Summary Autoxidation of methyl oleate and oleic acid beyond the peak peroxide values followed by catalytic hydrogenation gave mixed monohydroxystearic acids in high yield. The complicated autoxidation mixture which contains peroxides, hydroxy, carbonyl, and oxirane compounds was simplified considerably in composition by this procedure. For complete reduction of the double bond, and the carbonyl and oxirane groups, hydrogenation was conducted at about 150° and 150 lbs.. Peroxides were reduced at room temperature. Catalysts used were palladium on carbon and Raney nickel. The selective reduction of peroxides in autoxidation mixtures has been studied by chemical and catalytic means. Peroxides were converted largely to carbonyl compounds rather than to the anticipated hydroxy compounds. Palladium-lead on calcium carbonate is an excellent catalyst for reducing peroxides with hydrogen. tert-Butyl hydroperoxide, 12- ketostearic acid, stearone,cis-9,10-epoxystearic acid and methyl oleate peroxide concentrate were employed as model substances in determining hydrogenation conditions. Paper XVII. is reference 5. Presented at the fall meeting of the American Oil Chemists' Society, Minneapolis, Minn., Oct. 11–13, 1954. A laboratory of the Eastern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Reduction of methyl oleate ozonolysis products to aldehydes with activated zinc

Reduction of methyl oleate ozonolysis products with active zinc in the absence of acid or water gave an 88% yield of methyl azelaaldehydate. Under these neutral conditions, side reactions such as acetalization and aldehyde condensations could be more conveniently avoided than when zinc-acetic acid reduction is used. The activated zinc was prepared by treatment with acetic acid followed by washing to remove the acid. No. Utiliz. Res. and Dev. Div., ARS, USDA.     

Isomerization studies: II. Thermal alteration of oleic acid and methyl oleate in the presence of mineral catalysts

A structure analysis has been conducted on the distillable fraction (67–71%) obtained from the clay catalyzed isomerization of methyl oleate and oleic acid. The method of analysis involved the combined use of reductive ozonolysis, urea adduction, and gas liquid chromatography-mass spectrometry. The results of this study indicate that the original unsaturation of the fatty acid is mostly retained, but less than the theoretical amount of hydrogen is absorbed when the products are subjected to low pressure catalytic hydrogenation. These results in conjunction with the gas liquid chromatography-mass spectrometry data suggest that branching of the carbon chain has occurred.     

New Results of Free Radical Additions to Unsaturated Fatty Compounds

Unsaturated fatty acids such as oleic acid are 1,2-dialkyl substituted alkenes, which can be functionalized by free radical addition to the C, C double bond. We have been able to add enolizable compounds, e.g. acetone, acetic acid and malonic acid to methyl oleate mediated by manganese(III)acetate. Azide radicals, generated by manganese(III)acetate-oxidation of sodium azide, have also been added to methyl oleate. Perfluoralkyl iodides have been added via perfluoroalkyl radicals to methyl 10-undecenoate and methyl oleate to form the corresponding addition products. Reduction of the iodides by tributyltin hydride and saponification leads to interesting partially fluorinated fatty acids.     

Ozonation of sunflower oil: Spectroscopic monitoring of the degree of unsaturation

Consumption of ozone by unsaturated FA moieties of sunflower oil (SFO) was monitored by ¹H NMR and FTIR spectroscopy. Degradation of linoleate was found to be 1.5 and 1.8 times higher than oleate when SFO was ozonized in the absence and presence of water, respectively. Products of ozonation in both cases include aldehydes and ozonides with 1,2,4-trioxolane ring. Hydroxyl-containing compounds, which could be carboxylic acids and/or hydroperoxides, were also detected in samples ozonized in the presence of water. The extent of ozonation had very little effect on the aldehyde/ozonide ratio obtained from NMR spectra, especially in the ozonation of neast SFO. The aldehyde/ozonide ratios obtained regardless of the extent of ozonation were 10.5:89.5 and 46.6:53.4 for SFO ozonized in the absence and presence of water, respectively.     

1H NMR Study of Methyl Linoleate Ozonation.

Unsaturated fatty acids are essential components of vegetable oils and cellular membranes and the involved aspect of unsaturated fatty acids ozonation have been widely studied by different authors. In this paper, in vitro ozonolysis of unsaturated fatty acids with addition of water or ethanol has been studied by Proton Nuclear Magnetic Resonance (¹H NMR) at 250?MHz in order to explore the possibility of this technique for the detection of Criegee ozonides in characterizing ozone reaction with these substrates. The ozonolysis of methyl linoleate showed that signal intensities from formed ozonides were increased with ozone concentration increments. However, the signal intensities with addition of water were higher than those in ethanol addition. Signal intensities from olefinic double bonds were found to decrease with the increment in ozonide signals. Thus, a correspondence of the behavior of these signals is observed with a proportional rate reaction between the number of double bonds in the substrate molecule. Signals from aldehyde formation were poorly detected at lower ozone concentration. It was concluded that the evaluation of ozonide and olefinic double bond signals from 250?MHz ¹H NMR can be a useful tool in assessing ozone reaction with biomolecules. The reaction mechanism for the ozone reaction with unsaturated fatty acids in the presence of water or ethanol is analyzed.     

Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.     

Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.     

Hydrosilylation of long chain unsaturated fatty acid esters

The addition of a series of silicon hydrides: trichlorosilane, methyldichlorosilane, dimethylchlorosilane, phenyl dichlorosilane, and methyl phenyl chlorosilane to esters of long chain unsaturated fatty acids, such as oleic, linoleic acids, and 10-undecenoic acid, was studied with respect to catalysts, temperature, and solvents. Higher yields were obtained on carrying out the hydrosilylation reactions in the presence of chloroplatinic acid or Pt on C catalysts in bulk without solvent, as compared with peroxide catalysts. The addition reaction with methyl 10-undecenoate, which has a terminal double bond, gave a higher yield than that with methyl oleate. NMR data of the products from methyl 10-undecenoate and methyl oleate, as well as their reduction products with lithium aluminum hydride, have shown that, with the former ester, the silyl moiety added exclusively to the terminal carbon atom, while, with the latter, no migration of the silyl moiety to the terminal carbon atom was observed.     

Thermal oxidation of model molecules to reveal vegetable oil polymerization studied by NMR spectroscopy and self-diffusion

Oxidative polymerization of plant oils and lipids is poorly understood yet widely encountered. Oils and fats are renewable resources providing biofuels and polymers. Oil oxidation is accelerated at high temperatures, typically above 110°C, where triacylglycerides are converted into toxic compounds and viscous deleterious polymers. Polymerization of mono-unsaturated oil (210°C, 3 h, open to air) was investigated by comparing four similar sized molecules with different functional groups: oleic acid, methyl oleate, trans-7-tetradecene, and stearic acid. Non-volatile products identified by NMR spectroscopy are minor ketones for saturated fatty acid (stearic acid), epoxides for acyl chains without acid groups (methyl oleate, tetradecane) and copious oligomerization, through ester cross-links, for acyl chains with acid, and olefinic groups (oleic acid). Long range C H coupling clearly shows ester (not ether) cross-links, contradicting long-held beliefs. Chain fragmentation also occurs for heated oleic acid as revealed by formation of a species with a methylene group bonded to oxygen of an ester,  CH₂ O C(O) . Large size (slow diffusion) of the first oligomer (trimer) formed from oleic acid, used to represent hydrolyzed vegetable oil, was evidenced by DOSY (diffusion-ordered spectroscopy). Combined NMR results show oligomers found in heated oleic acid are fatty acid estolides. Model oil reactions demonstrate why olefin and carboxylic acid groups are required for polymerization.     

Quantification of Nonanal and Oleic Acid Formed During the Ozonolysis of Vegetable Oil Free Fatty Acids or Fatty Acid Methyl Esters

The ozonolysis of unsaturated lipids is a process that has been used to generate aldehydes, acids, alcohols, and other biobased chemical intermediates. Reported here is a method that can be used to measure the formation of nonanal and oleic acid during the ozonolysis of unsaturated vegetable oil fatty acids or their methyl esters to indicate the extent of the ozonolysis reaction. Derivatization was performed using boron trifluoride in methanol solution to transform nonanal and oleic acid into nonanal dimethyl acetal and oleic acid methyl ester, respectively. Undecanal and 10‐heptadecenoic acid were used as internal standards and separation was performed using gas chromatography coupled with a flame ionization detector. The method was validated by performing a standard addition procedure in which nonanal or oleic acid standards were spiked into samples collected during the ozonolysis of oleic acid or canola oil fatty acid methyl ester (FAME). Linear regression results indicated that the measured nonanal and oleic acid are in good agreement with the actual amounts of nonanal and oleic acid added to the sample with at least 98 % recovery. The application of the method was demonstrated by the successful measurement of nonanal and oleic acid formed throughout the ozonolysis process for high oleic canola oil FAME.     

Identification of (e)-11-hydroxy-9-octadecenoic acid and (E)-9-hydroxy-10-octadecenoic acid by biotransformation of oleic acid by Pseudomonas sp. 32T3

Pseudomonas sp. 32T3, a newly identified strain originally isolated from a vegetable oil-contaminated soil, produces three monohydroxy acids—(E)-11-hydroxy-9-octadecenoic acid, (E)-10-hydroxy-8-octadecenoic acid, and (E)-9-hydroxy-10-octadecenoic acid—as bioconversion products of oleic acid. The bacterial cells were grown in a mineral medium containing oleic acid as the main carbon substrate. The compounds were identified as the corresponding methyl esters on the basis of their chromatographic and spectroscopic (¹H and ¹³C nuclear magnetic resonance and gas chromatography-mass spectrometry) features.     

Influence of high energy radiation on oxidation of oleic acid and methyl oleate

Summary 1. Gamma radiation from Cobalt 60 influences the oxidation of oleic acid and methyl oleate even at low temperatures. 2. Determination of peroxide values, carbonyl values, and the E _1cm ^1% . values at 224 mμ revealed that high peroxide values could be obtained but that secondary products are formed in appreciable quantities. 3. The products causing absorption at 224 mμ may be α,β-unsaturated ketones. The level of these substances can be increased by irradiation-oxidation in the presence of metal soaps such as cobalt stearate. 4. Irradiation-oxidation of methyl oleate through a series of temperature ranges from 7.5°C. to 55°C. reveals a marked thermal activation effect. Peroxide values of 2000 me/kg or greater are obtained in 100 hrs. of reaction time. Journal Paper No. 125, American Meat Institute Foundation. Supported by a grant from the National Renderers Association and from Darling and Company. Presented at the fall meeting, American Oil Chemists’ Society, Philadelphia, Pa., Oct. 10–12, 1955.     

Radikalische Additionen an ungesättigte Fettstoffe

Free Radical Additions to Unsaturated Fatty Acids Unsaturated fatty acids e.g. oleic acid are 1,2-dialkyl substituted alkenes with an electron-rich C,C-double bond. Elektrophilic free radicals can be added to the double bond to give functionalized and branched fatty acids. The electrophilic free radicals have been generated a) by oxidation of enolizable compounds by manganese (III) acetate prepared in situ by addition of potassium permanganate to catalytic amounts of manganese (II) acetate; b) with di-tert.-butylperoxide as initiator. Free radical addition of the radical to methyl oleate occurs to give an adduct radical which can be stabilized by hydrogen transfer or by oxidative elimination with copper (II) acetate. We have been able to add also alkanes e.g. cyclohexane to methyl oleate. A review of free radical additions to oleic acid is given.     

Study of Ozonated Olive Oil: Monitoring of the Ozone Absorption and Analysis of the Obtained Functional Groups

The peculiarities of ozone absorption during olive oil ozonolysis have been studied by continuous monitoring of ozone concentrations at the bubbling reactor outlet. The determined amount of ozone, consumed during the ozonolysis of the double bonds, was used as alternative way for evaluation of the degree of unsaturation of the oil. The basic functional groups, products of the reaction: ozonides and aldehydes have been quantitatively characterized by means of ¹H-NMR spectroscopy, whereupon their ratio was found to be 93.4:6.6 (mol. %), respectively. The determined ratio between the cis and trans ozonides was 46:54.     

Synthesis of (S)-α-amino oleic acid

An efficient synthesis of (S)-α-amino oleic acid was developed. The fully protected FA derivative was obtained in four steps starting from methyl (2S)-2-[bis(tert-butoxycar-bonyl)amino]-5-oxopentanoate. These steps are (i) olefination of the starting aldehyde with the appropriate phosphonate anion, (ii) hydrogenation of the double bonds, (iii) controlled reduction of ω-ethyl ester to an aldehyde in the presence of α-methyl ester, and (iv) a Wittig reaction of the latter aldehyde with the suitable ylide. Free α-amino oleic acid was prepared after deprotection of the amino group followed by saponification in a total yield of 24%. N-tert-Butoxycarbonyl-protected amino oleic acid and the corresponding amino alcohol were prepared in high yield. The structures of the products have been established by various spectroscopic techniques.     

Lewis Acid Induced Additions to Unsaturated Fatty Compounds

Unsaturated fatty compounds such as oleic acid, which are of interest as renewable raw materials, can be functionalized at the C,C-double bond by Lewis acid induced addition reactions. The products are branched and highly functionalized fatty compounds which may have interesting properties. SnCl₄-induced additions of nitriles to methyl oleate and ethyl 10-undecenoate give the corresponding esters of the N-acylamino fatty acids. Alkylaluminium halide induced ene additions of formaldehyde to unsaturated fatty compounds yield primary homoallylic alcohols. β,γ-Unsaturated ketones are obtained in ethylaluminium dichloride induced Friedel-Crafts acylations of unsaturated fatty compounds with acyl chlorides and cyclic anhydrides.