Omega-formylalkanoates by ozonization of unsaturated fatty esters

Ozonization of the methyl esters of 11-eicosenoic, linoleic, erucic and linolenic acids gave a number of different homologous methyl ω-formylalkanoates. Complete ozonization of the monounsaturated esters formed C₁₁ and C₁₃ compounds with 90% conversion; partial ozonization of the polyunsaturated esters gave C₁₂ and C₁₅ products with maximum conversions at ca. 75% consumption of fatty ester. Thus, methyl linoleate gave 52 and 23% conversions to the 9- and 12-carbon products, and methyl linolenate gave 29, 27 and 19% conversions to the 9-, 12- and 15-carbon products. Yields of aldehyde or acetal esters in distilled products were 70–90% in preparative-scale experiments. Kinetic analysis showed that ozone attack was essentially random. Methanol was used as a participating solvent. Presented in part at the AOCS Meeting, New Orleans, 1962. A laboratory of the No. Util. Res. & Dev. Div., ARS, USDA.     

The fatty acids of menhaden oil

Summary The methyl esters of a specimen of menhaden oil have been fractionated in an efficient still. The C₁₂, C₁₄, C₁₆, and C₁₈ main fractions have been studied, mainly by low temperature crystallization procedures. The oil has been shown to contain traces of lauric and dodecenoic acids. The C₁₄ acids are made up of 2.2% tetradecenoic acid and 97.8% of myristic; based on the whole ester composition of Table I, these values amount to 0.1 and 6.8%, respectively. The C₁₆ acids are palmitic, 50.9%; hexadecenoic, 46.6%; and hexadecatrienoic (including a small amount of tetrenoic acid) 2.5%, or based on the whole esters, 15.5, 14.1 and 0.8%, respectively. A very rough calculation of the composition of the C₁₈ fraction gives the following reults, values based on the whole esters being included in parenthesis: stearic, 11.5 (3.1); octadecenoic, 58.6 (15.7); octadecadienoic, 13.4 (3.6); octadecatrienoic, 7.2 (1.9); and octadecatetrenoic, 9.3% (2.5%). In the course of this investigation the following acids and their methyl esters were isolated from the oil by crystallization procedures; myristic, tetradecenoic (80%), palmitic, hexadecenoic, stearic, and oleic. Evidence was presented that the octadecenoic acids of this oil were a mixture of oleic acid with isomeric acids of this series, a finding which is in agreement with a recent report from this laboratory (11), describing the multiple nature of the octadecenoic acids of a number of animal fats. Presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School.     

Jojoba oil wax esters and derived fatty acids and alcohols: Gas chromatographic analyses

HCl-catalyzed ethanolysis followed by saponification readily surmounts the resistance of long chain wax esters to direct hydrolysis by alkali. Additionally, choosing ethyl instead of methyl esters allows baseline separations between long-chain alcohols and corresponding esters in gas liquid chromatographic (GLC) analysis of total alcohol and acid components before saponification. Liquid wax esters were analyzed on a temperature-programmed 3% OV-1 silicone column. Geographical and genetic effects on the variability of jojoba oil composition were investigated with five different seed samples. Major constituents in jojoba seed oil from shrubs in the Arizona deserts, as indicated by GLC analyses of oil, ethanolysis product, isolated fatty alcohols and methyl esters of isolated fatty acids, were C₄₀ wax ester 30%, C₄₂ wax ester 50% and C₄₄ wax ester 10%; octadecenoic acid 6%; eicosenoic acid 35%, docosenoic acid 7%, eicosenol 22%, docosenol 21% and tetracosenol 4%. Oil from smaller leaved prostrate plants growing along California’s oceanside showed a slight tendency toward higher molecular size than oils from the California desert and Arizona specimens. The wax esters are made up of a dispro-portionately large amount of docosenyl eicosenoate and are not a random combination of constituent acids and alcohols.Lunaria annua synthetic wax ester oil was used as a model for evaluating the analytical procedures. Presented at the AOCS Meeting, Chicago, September 1970 No. Utiliz, Res. Dev. Div., ARS, USDA.     

Biochemical and physiological studies of certain ticks (Ixodoidea): Isolation and partial identification of a new fatty acid in eggs ofDermacentor andersoni Stiles (Ixodidae)

Gas liquid chromatographic analysis of the fatty acid methyl esters from eggs ofDermacentor andersoni Stiles (Ixodidae) revealed the presence of significant quantities (15% total fatty acids) of an unidentified component with a retention time between C_18∶3−C_22∶0 fatty acids. Smaller amounts of the unidentified component (ca. 5% total fatty acid) also were detected in host rabbit serum. Purified, the unidentified component's methyl ester collected from the tick eggs by preparative gas liquid chromatography was partially identified and characterized by chemical and spectroscopic analyses. The evidence suggests that the unidentified component is a methyl branched C₁₅ tricarboxylic acid containing two vicinal carboxylic acid groups. Biosynthesis of the unidentified component by the tick is under investigation.     

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C₁₈ reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.     

The reaction of mercaptoacetic acid with methyl linoleate and linoleic acid

The reaction of mercaptoacetic acid with methyl linoleate and with linoleic acid was investigated. The reaction proceeded at low and erratic rates, with and without catalysts, such as peroxides at various temperatures, but could be accelerated by use of a large excess of mercaptoacetic acid. Addition of 1 mole of mercaptoacetic acid to 1 mole of methyl linoleate resulted in a product containing about 40% of mono-adduct. Ozonolysis of the purified mono-adduct yielded approximately equimolar quantities of caproic and azelaic acids, indicating that addition occurred about equally at the 9,10- and 12,13-ethylenic bonds. The dicarboxylic acid and the dimethyl ester of the mono-adduct and the tricarboxylic acid and trimethyl ester of the di-adduct of linoleic acid and mercaptoacetic acid were prepared, and the infrared spectra and some physical and chemical characteristics of these products were determined. The infrared spectra of the reaction products were obtained and correlated with functional groups which give rise to them. Bands at about 7.8 and 8.8 μ, commonly observed in long chain acids and esters and ascribed to C−O vibrations, are intensified in the sulfur-containing reaction products, suggesting characteristic absorption of C−S compounds at almost identical wavelengths. The formation of adducts was accompanied by a high degree of isomerization of the unreacted ethylenic bonds from thecis to thetrans form both in the mono-adduct and in unreacted methyl linoleate. The methyl linoleate recovered contained about 12% diene conjugation, but catalytic quantities of mercaptoacetic acid were not effective in inducing conjugation.     

The composition of furan fatty acids in the crayfish

Capillary gas chromatography-mass spectrometry (GC-MS) analysis of the sterol ester fatty acid methyl esters of the crayfish hepatopancreas revealed the presence of at least 30 kinds of unusual furan fatty acids (F acids), which accounted for 28.49% of the total sterol ester fatty acids. On the other hand, only small amounts were found in triacylglycerols (0.5%) and phospholipids (0.7%). Among the F acids, 17 acids were the hitherto unknown ones, the major component being 12,15-epoxy-13,14-dimethyleicosa-12,14-dienoic acid (F₆) (41.83% of the total F acids). These novel acids possessed chain lengths of C₁₂ to C₂₂, with the largest concentration at C₂₀ (45.38%), C₁₈ (41.97%) and C₁₆ (10.35%). Odd-numbered F acids also were found, though in a very small amount (0.4%). In the living things other than the crayfish, the longest chain F acid (C₂₄) was detected in the sterol ester of the carp hepatopancreas. The bullfrog, an amphibian, and the turtle, a reptilian, were found to have F acids as well in their livers. Olefinic furan fatty acids, which were detected by GC-MS, were found to have resulted during the analytical process from cyclodehydration of the diketo-ene formed by autoxidation of the F acids.     

The fatty acids of wax esters and sterol esters from vernix caseosa and from human skin surface lipid

Separation of sterol esters from wax esters in the lipids of vernix caseosa and adult human skin surface was accomplished by column chromatography on MgO. The fatty acids of the sterol esters and wax esters of both samples were separated into saturates and monoenes, and examined in detail by gas liquid chromatography (GLC). The saturated fatty acids of the wax esters of vernix caseosa and of adult human skin surface were remarkably similar. They ranged in chain length from at least C₁₁ to C₃₀, six skeletal types being present: straight even, straight odd, iso, anteiso, other monomethyl branched and dimethyl branched. A large number of patterns of monoenes were observed, each pattern consisting of desaturation of a specific chain at Δ6 or Δ9 plus its extension or degradation products. The mole per cent of the total Δ6 and Δ9 patterns of wax ester fatty acid monoenes of vernix caseosa were 87% and 12%, respectively, and 98% and 1%, respectively, for adult human skin surface lipid. The sterol ester fatty acids of vernix caseosa were much different from those of adult human skin surface: vernix caseosa saturates were largely branched and of lengths greater than C₁₈, whereas the saturates of adult human surface lipid resembled the wax ester fatty acids. Of the vernix caseosa monoene patterns, the mole per cent was 30% Δ6 and 70% Δ9, whereas of the adult human skin surface sterol ester fatty acids 89% were Δ6 and 11% Δ9. Chain extension was particularly pronounced in the sterol ester fatty acid monoenes of vernix caseosa amounting to 7–8 C₂ units in some cases. The fatty acids of the sterol esters of both vernix caseosa and adult human skin surface appear to be derived from the sebaceous gland and from the keratinizing epidermis, but those of the wax esters are from the sebaceous glands only.     

Stereospecific hydration of unsaturated fatty acids by bacteria

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.     

Fatty acid composition of human and rat adrenal lipids: Occurrence of ω6 docosatrienoic acid in human adrenal cholesterol ester

Fatty acids in human and rat adrenal lipids were analyzed by A_gNO₃-impregnated silica gel, thin layer chromatography and gas liquid chromatography (GLC). In human adrenal cholesterol ester, 26 kinds of fatty acids were estimated. The percentage of 18∶1 was highest, and 20∶3ω6 and 22∶4ω6 represented high percentages in polyenoic acids. Docosatrienoate was found in all the five men, representing from 1.0% to 2.8%. Its retention time on GLC was different from that of 22∶3ω9 found in the adrenal cholesterol ester of fat deficient rats. The methyl esters of dicarboxylic acids produced by KM_nO₄-oxidation of the docosatrienoate had a chain of 10 carbon atoms. These results elucidate that the docosatrienoate from human adrenal cholesterol ester belongs to the linoleate family. In the adrenal cholesterol ester of 10-week fat free rats, the percentages of 22∶4ω6 and 22∶5ω6 did not decrease, compared with control rats, though arachidonate apparently decreased. The adrenal phospholipid contained about 20% of arachidonate in four of five men and about 40% of arachidonate in rats. Much more polyenoic acids were found in the triglyceride of an adrenal adenoma of primary aldosteronism than in the adjacent adrenal tissue, shereas the fatty acid compositions of phospholipid and cholesterol ester in the adenoma resembled those in the adjacent tissue.     

Study on the oxidative rate and prooxidant activity of free fatty acids

Oleic, linoleic and linolenic acids were autoxidized more rapidly than their corresponding methyl esters. Addition of stearic acid accelerated the rate of autoxidation of methyl linoleate and the decomposition of methyl linoleate hydroperoxides. Therefore, the higher oxidative rate of FFA’s than their methyl esters could be due to the catalytic effect of the carboxyl groups on the formation of free radicals by the decomposition of hydroperoxides. Addition of stearic acid also accelerated the oxidative rate of soybean oil. This result suggests that particular attention should be paid to the FFA content that affects the oxidative stability of oils.     

Screening vegetable oil alcohol esters as fuel lubricity enhancers

Methyl and ethyl monoalkyl esters of various vegetable oils were produced for determining the effects of type of alcohol and fatty acid profile of the vegetable oil on the lubricity of the ester. Four methyl esters and six ethyl esters were analyzed for wear properties using the American Society for Testing and Materials method D 6079, Evaluating Lubricity of Diesel Fuels by the High-Frequency Reciprocating Rig. Ethyl esters showed noticeable improvement compared to methyl esters in the wear properties of each ester tested. No correlation was found between lubricity improvement and fatty acid profile of the ester, except that esters of castor oil had improved lubricity over other oils with similar carbon chain-length (C₁₈) fatty acids.     

A novel method for the introduction of a methyl group into the furan ring of a 2,5-disubstituted C18 furanoid fatty estervia a malonic acid function

Furan ring opening with benzohydroxamic acid of methyl 9,12-epoxy-9,11-octadecadienoate gave a mixture of positional isomers of conjugated methyl 3-phenyl-1,4,2-dioxazolyl C₁₈-enone esters 6a,6b. Michael addition of diethyl malonate anion to the conjugated enone system of 6a,6b furnished the corresponding malonyl intermediates 7a,7b, which upon removal of the dioxazole ring by hydrolysis gave methyl 10- and 11-dicarbethoxymethyl-9,12-dioxooctadecanoate 8a,8b. Cyclization of the latter gave the trisubstituted C₁₈ furanoid fatty esters 9a,9b, containing the malonate ester function at the 3-/4-position of the furan ring. Base hydrolysis of compounds 9a,9b gave the corresponding tricarboxylic acid derivatives 10a,10b, which were esterified to the trimethyl esters 11a,11b in BF₃/MeOH. When a mixture of 9a,9b was refluxed with Na₂CO₃/MeOH, hydrolysis of the malonate ester function was followed by decarboxylation to yield a-CH₂COOH substituent at the 3-/4-position of the furan ring (12a, 12b). Esterification of the latter with BF₃/MeOH gave the corresponding methyl diester derivatives 13a,13b. When a mixture of tricarboxylic acids 10a,10b was heated at 160–180°C for 6 hr, exhaustive decarboxylation of malonic acid function furnished a methyl group at the 3-/4-position of the furan nucleus. Esterification of the decarboxylated product gave a mixture of trisubstituted furanoid compounds 14a,14b (overall yield 28%). The procedure constitutes a novel method for the introduction of a methyl groupvia a malonic acid group to the 3-/4-position of the furan ring of a 2,5-disubstituted C₁₈ furanoid fatty ester.     

Solubility behavior of ternary systems of lipids in supercritical carbon dioxide

In this review, the phase behavior of lipids in ternary and higher systems was analyzed to determine the effect of operating parameters and feed composition on solubility behavior and separation efficiency. The ternary systems studied included two triglycerides (TG) (trilaurin (LLL)/tripalmitin (PPP), trimyristin (MMM)/PPP and LLL/MMM), two fatty acids (FA) (oleic acid (OA)/linoleic acid (LA)), two fatty acid methyl esters (FAME) (methyl myristate (MeM)/methyl palmitate (MeP) and methyl oleate (MeO)/methyl linoleate (MeL)), FA/TG (OA/triolein (OOO)) and FAME/FA (MeO/OA) in SCCO₂. The quaternary and quinary systems analyzed contained three TG (LLL/MMM/PPP), three glycerides (monoolein (MO)/diolein (DO)/OOO) and four TG (PPP/palmitoyl-dioleoylglycerol (POO)/oleoyl-dipalmitoylglycerol (PPO)/OOO), respectively, in SCCO₂. While solubility of the less soluble component increased in ternary systems of solid triglycerides in SCCO₂, that of the more soluble component decreased or was not affected. Solubility diminution was observed for both solutes in some liquid mixtures such as fatty acid (oleic acid/linoleic acid) and fatty acid ester (methyl oleate/methyl linoleate) mixtures. Solubility enhancement for one of the mixture components was also observed (for example, for oleic acid in the presence of methyl oleate). Separation efficiency was lower than that predicted by binary data when the solubility of the less soluble solute was enhanced in the mixture, whereas it was improved if the solubility of the more soluble component was enhanced as observed in quaternary glyceride mixtures.     

Search for new industrial oils: XVI. Umbelliflorae—seed oils rich in petroselinic acid

Seed oils of the order Umbelliflorae, including those from the families Umbelliferae, Garryaceae, Araliaceae, Cornaceae, Davidiaceae, Nyssaceae and Alangiaceae, were analyzed for fatty acid composition by gas liquid chromatography (GLC) of their methyl esters. The characteristic fatty acid of the order, petroselinic acid, occurred in the Umbelliferae in amounts up to 85%. In the Araliaceae, the content was as high as 83% and in the Garryaceae as high as 81%. The other major acids were palmitic, oleic and linoleic acids, with small amounts of hexadecenoic, stearic, linolenic, and, in some cases, C₂₀ acids. petroselinic acid was determined by microscale ozonolysis of the C₁₈ monoenoic esters and subsequent GLC of the ozonolysis products. The occurrence of high oil contents (up to 46%) combined with exceptionally high (up to 83%) single component purity is notable and emphasizes the potential of the Umbelliflorae as a raw material source for the chemical industry.     

Analysis of the dark-colored impurities in sulfonated fatty acid methyl ester

A fractionally distilled C₁₄−C₁₆ fatty acid methyl ester, derived from palm oil, was sulfonated with gaseous SO₃ in a falling film reactor to form an α-sulfo fatty acid methyl ester (α-SF; unbleached and unneutralized form). The included dark-colored impurities were then separated from α-SF as a diethyl ether-insoluble matter. After purification by thin-layer chromatography, the colored species were analyzed by ion-exchange chromatography, gel-permeation chromatography, and nuclear magnetic resonance spectrometry. These data suggested that the colored species were polysulfonated compounds with conjugated double bonds. Minor components in the raw fatty acid methyl ester, found by gas chromatography/mass spectrometry, were spiked into the purified methyl palmitate and then sulfonated. The unsaturated methyl ester and hydroxy ester showed the worst color results. The methyl oleate and methyl 12-hydroxystearate were then sulfonated and analyzed. Deep black products were obtained, which showed the same properties as the colored species in α-SF. It was concluded that low levels of unsaturated fatty acid methyl esters and hydroxy esters in the fatty acid methyl ester are the main causes of the coloring.     

θ3 fatty acids in freshwater fish from south brazil

Lipid and fatty acid levels in the edible flesh of 17 freshwater fish from Brazil’s southern region were determined. Analyses of fatty acid methyl esters were performed by gas chromatography. Palmitic acid (C_16:0) was the predominant saturated fatty acid, accounting for 50–70% of total saturated acids. Oleic acid (C_18:1θ9) was the most abundant monounsaturated fatty acid. Linoleic acid (C_18:2θ6), linolenic acid (C_18:3θ3), and docosahexaenoic acid (C_22:6θ3) were the predominant polyunsaturated fatty acids (PUFA). The data revealed that species such as truta, barbado, and corvina were good sources of eicosapentaenoic acid (C_20:5θ3) and docosahexaenoic acid (C_22:6θ3), and that most freshwater fish examined were good sources of PUFA θ3.     

Thermal reactions of methyl linoleate. II. The structure of aromatic C18 methyl esters

This second report describes the characterization of C₁₈ aromatic esters from the heated linoleate and the independent synthesis of two of them. The esters were isolated by a combination of molecular distillation, urea adduction, column chromatography, and gas chromatography. They were characterized by infrared, ultraviolet, NMR, and mass spectroscopy. The analytical data for the isolated esters were compared with the data for the synthetic esters, methyl 11-(2′-methylphenyl) undecanoate, methyl 7-(2′-pentylphenyl) heptanoate, and methyl 8-(2′-butylphenyl) octanoate. The latter two compounds were found to be components of the aromatic fraction isolated from heated linoleate, and their synthesis is deseribed in detail.     

Fractional vacuum distillation of herring oil methyl esters

Methyl esters of a Canadian Atlantic herring oil containing 62% monoethylenic fatty acids were subjected to batch fractional distillation under vacuum on a pilot plant scale, to study the feasibility of fractionating fatty acid esters of marine oils of low iodine value into monounsaturated fractions with increased commercial value for industrial chemical uses. A total of 64 methyl ester fractions were collected and analyzed by gas liquid chromatography. Recoveries of the major saturated and monounsaturated acids were close to 100%, and some fractions contained over 90% of the desired 22:1 long chain monounsaturated acids. The short chain polyunsaturated acids were recovered in good yields, but the long chain highly unsaturated acids were recovered in yields of 60% or less due to oxidative and thermal decomposition in the particular apparatus employed. If small amounts of unsaturated acids are acceptable, fractional distillation of low iodine value marine oils could inexpensively supply fractions with high concentrations of methyl esters of longer chain (C₂₀ and C₂₂) monounsaturated and shorter chain (C₁₄) saturated acid or (C₁₆) saturated-monounsaturated acid mixture.     

Production of branched-chain fatty acids from sterculia oil

Methyl sterculate was rearranged by use of 0.5% of rhodium catalyst to isomeric conjugated diene fatty acid methyl esters containing both methylene-and methyl-branched isomers. The rearanged products were hydrogenated directly to saturated, methyl-substituted, branched-chain fatty acid methyl esters with the methyl substituent at one of the positions formerly occupied by the cyclopropenoid ring. The crude branched-chain fatty acids from these esters were purified by recrystallization from a mixed solvent of ethanol and water (80:20, v/v) and flash distillation; the product contained about 90% of branched-chain fatty acids (C₁₉:80%, C₁₈:10%). Esters of the branched-chain fatty acid were prepared with 2-ethylhexyl alcohol or trimethylolpropane, and the characteristic properties of these esters were investigated. The branched-chain fatty esters appear to have potential utility in lubricants; other uses may be possible. Presented at the AOCS meeting in New Orleans, May 1981.