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.     

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.     

Esterification and interesterification reactions catalyzed by acetone powder from germinating rapeseed

Acetone powder from germinating rape (Brassica napus L.) seedlings exhibits essentially similar activity in lipolysis of triacylglycerols as the corresponding seedling homogenates. Acetone powder from rape seedlings catalyzes the esterification of a fatty acid, such as oleic acid, withn-butanol or a long-chain alcohol, such as oleyl alcohol. Furthermore, the acetone powder catalyzes alcoholysis of a methyl ester, such as methyl oleate withn-butanol or oleyl alcohol, and acidolysis of methyl oleate with a fatty acid, such as erucic acid. However, triacylglycerols are not accepted as substrates fro interesterification reactions. In esterification of fatty acids withn-butanol, catalyzed by the acetone powder from rape seedlings, fatty acids having an olefinic bond next to the carboxyl group as acis-6 double bond, e.g., γ-linolenic, gorlic and petroselinic acids, or those having acis-4 double bond, e.g., docosahexaenoic acid, are strongly discriminated against as substrates. Such substrate selectivities can be utilized for the enrichment of definite fatty acids from mixtures, derived from naturally occurring oils,via kinetic resolution. Part of the doctoral thesis of Iván Jachmanián to be submitted to Facultad de Química. Universidad de la República, Montevideo, Uruguay.     

The biosynthesis of polyunsaturated fatty acids in plants

This paper is a review of some of the work being done at the author's laboratory. The phospholipids and glycolipids of the alga,Chlorella vulgaris, have been implicated in fatty acid transformations such as chain elongation and desaturation. Labeling studies with [¹⁴C] acetate have shown that newly synthesized galactosyl glycerides have mainly saturated fatty acids. Subsequent to de novo synthesis, a series of alterations of fatty acid structure takes place within the same glycolipid molecules. The specific incorporation of [¹⁴C] oleic acid intoChlorella phosphatidyl choline provides a convenient model system for studying the lipid dependent desaturation of oleic to linoleic acid. The inhibitor of fatty acid desaturation, sterculic acid, only inhibits the conversion of oleate into linoleate if added before the precursor fatty acid has been incorporated into a complex lipid. Studies with isomeric monoenoic fatty acids have suggested that there are two enzymes which catalyze the formation of linoleic from oleic acid. One measures the position of the second double bond from the carboxyl group, the other, from the methyl end of the chain. The latter enzyme probably requires the complex lipid substrate.     

Cyclopropanation of unsaturated fatty acid methyl esters using diazomethane and palladium (II) acetate

Cyclopropanation of methyl esters of 10-undecenoic, oleic, elaidic, erucic,trans-2-docosenoic and a mixture of hydnocarpic and chaulmoogric acids was effected using diazomethane in the presence of palladium (II) acetate as catalyst. The products were isolated by silver ion thin-layer chromatography and characterized by infrared, proton nuclear magnetic resonance and mass spectrometric techniques. Terminally unsaturated, α, β-unsaturated and cyclopentene fatty acid esters were found to be more reactive than elaidate which in turn was more reactive than oleate. The reaction proceeds stereospecifically under milder conditions in a shorter time than with diiodomethane and zinc-copper couple.     

Oviposition response ofLobesia botrana females to long-chain free fatty acids and esters from its eggs

Avoidance of occupied ovisposition sites supposes that females perceive information related to their own progency. Fatty acids identified from egg extracts have been reevaluated using a different extraction method, and we have investigated the dose-dependent oviposition response of European grape vine moths (Lobesia botrana) to myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, methyl palmitate, methyl oleate, and ethyl palmitate; all except ethyl palmitate have been identified from eggs ofL. botrana. A methylene dichloride extract of eggs fromL. botrana revealed the presence of saturated free fatty acids (myristic, palmitic, and stearic) and unsaturated acids (palmitoleic, oleic, linoleic, and linolenic) in amounts ranging from 3.9 ng/egg equivalent for myristic acid to 30 ng/egg equivalent for palmitic and oleic acids. The extract also contained traces of methyl palmitate and methyl stearate. The greatest avoidance indexes were observed in response to palmitic, palmitoleic, and oleic acids. All the other compounds tested caused weaker responses. A reduction in the number of eggs laid was observed when moths were exposed to each of the esters applied at 0.3 µg per application spot. Reduction in eggs laid was also observed at a 10-fold higher dose of oleic acid. The present results confirm that general and simple molecules can be involved in the regulation of oviposition site selection and that they may participate in chemical marking of the eggs.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung III: Metallische und metallisch-oxidische Kupfer-Cadmium-Kontakte

Reduction of Unsaturated Fatty Acids and Their Esters to Unsaturated Fatty Alcohols by Selective Catalytic High Pressure Hydrogenation III: Metallic and Metal Oxide Copper-Chromium Catalysts Influence of catalyst composition and reaction conditions on the high pressure reduction of unsaturated fatty acids and their esters is described for metallic and mixed metal oxide copper-chromium catalysts. From these investigations and from a comparison with the efficacy of other metals in hydrogenation a hypothesis on the mechanism of the catalytic reaction in the reduction of carboxyl group and saturation of C? C double bonds is developed. The optimum reaction data of oleic acid and methyl oleate, which were used as test substances, are given.     

Synthesis of alkyl‐branched fatty acids

Alkyl‐branched fatty compounds are of interest for industrial products in the cosmetics and lubricant areas. In this review, clay‐ and zeolite‐catalyzed isomerizations of unsaturated fatty compounds, especially of oleic acid, are discussed. While clay‐catalyzed reactions give most complex mixtures of dimeric fatty acids and of monomeric so‐called “isostearic acid”, the zeolite‐catalyzed process yields preferentially an isomeric mixture of isostearic acids having the methyl branch on the 8–14 positions of the alkyl chain. Synthetically useful additions of alkyl radicals can only be performed on ω‐unsaturated fatty compounds, whereas perfluoroalkyl iodides were added to fatty compounds with terminal as well as internal double bonds using electron transfer‐initiated radical addition reactions. Electrophilic additions of alkyl carbenium ions generated by decomposition of alkyl chloroformates by ethylaluminum sesquichloride give well‐defined alkyl‐branched oleochemicals with good yields.     

Free radical additions to esters of unsaturated fatty acids. Preparation of dicarboxylic acids and other polyfunctional products

Peroxide initiated free radical addition of acetic acid, acetic anhydride and ethyl cyanoacetate to methyl undecylenate and methyl oleate gives interesting and important derivatives in fair to excellent yields. Of these, the most important are the dicarboxylic acids, brassylic and carboxymethylstearic acids. Acetic acid and acetic anhydride both give the same ultimate products but because of the greater amount of by-product in the methyl undecylenate reaction with acetic acid and the need for pressure in the reaction of acetic acid with methyl oleate, acetic anhydride is the preferred addendum for preparing the dicarboxylic acids. There is very little by-product formed in addition of acetic anhydride to methyl undecylenate and methyl oleate. Ethyl cyanoacetate adds readily to both methyl undecylenate and methyl oleate; however, ethyl cyanoacetate is difficult to remove completely from the reaction products. Hydrolysis to destroy it also causes some hydrolysis of the addition products. On the other hand, it is very difficult to hydrolyze completely and subsequently decarboxylate the ethyl cyanoacetate addition products of methyl undecylenate and methyl oleate to obtain dicarboxylic acids. Pressented at the Fall Meeting of the AOCS, Chicago, Ill., October, 1964. E. Utliz. Res. Dev. Div. ARS, USDA.     

Preparation of heptadecenoic acid fromCandida tropicallis yeast

In this paper a method is described for preparing 10 g or more of heptadecenoic acid (C17:1ω8) of 99 p.100 purity fromCandida tripicallis yeast. Three cycles of treatment, based on crystallization techniques, were used successively: (1) Crystallization of fatty acids (in free form) from acetone at −25 C induced the elimination of most of the saturated fatty acids, and at −60 C, of all of the poly-unsaturated acids. (2) Inclusion formation of fatty acids (as methyl esters) with urea at hC induced the removal of all of the remaining saturated methyl esters and most of methyl oleate. (3) Crystallization of fatty acid methyl esters from acetone at −60 C removed almost all the remaining monounsaturated methyl esters (methyl palmitoleate and methyl oleate). Total efficiency of the preparation was about 17 p. 100.     

Chemoattraction ofBiomphalaria glabrata (Gastropoda: Planorbidae) to lipid standards and lipophilic factors in leaf lettuce and Tetramin

Chemoattraction of individualBiomphalaria glabrata snails for lipid standards and lipophilic fractions of leaf lettuce and Tetramin were studied in a Petri dish bioassay. Snails were more significantly attracted to a whole Tetramin lipophilic fraction than that of leaf lettuce. Thin-layer chromatography showed that major neutral lipid fractions in Tetramin were triacylglycerols, free fatty acids, and free sterols, and in leaf lettuce were free fatty acids and a mixed free sterol-chlorophyll fraction. Snails were significantly attracted to both the free fatty acid and free sterol fractions from Tetramin, but only to the free fatty acid fraction from leaf lettuce. Snails were significantly attracted to a mixed lipid standard containing equal amounts of phosphatidylcholine, cholesterol, oleic acid, triolein, and cholesteryl oleate. Of four individual neutral lipid standards tested, i.e., cholesterol, oleic acid, triolein, and cholesteryl oleate, snails were only attracted to cholesteryl oleate.     

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.     

Lewis Acid Catalyzed Additions to Unsaturated Fatty Compounds. II: Alkylaluminium Halide Catalyzed Ene Reactions of Unsaturated Fatty Compounds and Formaldehyde

We are presenting our results on the alkylaluminium halide catalyzed ene addition of formaldehyde to readily available unsaturated fatty compounds to give primary homoallylic alcohols. The reaction of oleic acid and 10-undecenoic acid with formaldehyde gives (E)-9(10)-(hydroxymethyl)octadec-10(8)-enoic acid and 12-hydroxydodec-9-enoic acid, respectively, in high yields. Formaldehyde can be added also to oleyl alcohol to give the very interesting diol (E)-9(10)-(hydroxymethyl)oxtadec-10(8)-en-l-ol. Me₂AlCl and EtAl-sesquichloride are the most suitable catalysts for these reactions. The addition of formaldehyde to methyl oleate and methyl 10-undecenoate, respectively, to give the corresponding ene products is catalyzed by EtAlCl₂.     

Chemical reactions at lipid-gas interfaces: I. Terminal chain elongation of fatty acids

Reactions of free methyl radicals and monolayers of potassium palmitate and of potassiumn-heptadecanoate on an aqueous surface yielded straight chain saturated fatty acids containing longer hydrocarbon chains than those of the reactant acids. Similar results were obtained from the reactions of free ethyl radicals and potassium palmitate under similar conditions. The results of this investigation indicate that extension of hydrocarbon chains by free radical addition reactions can be achieved if the growing chains are suitably packed in a monolayer on a surface.     

Effects of protected cyclopropene fatty acids on the composition of ruminant milk fat

Unsaturated fatty acids can be protected from ruminal hydrogenation, and, when fed to lactating ruminants, the constituent acids are incorporated into milk triacylglycerols. By this means, it has been possible to reduce the melting point of milk triglycerides and to make softer butter fat. This report shows that, by feeding small amounts of protected cyclopropene fatty acids, one is also able to make harder butter fat.Sterculia foetida seed oil, a rich source of cyclopropene fatty acids, was emulsified with casein and spray dried to yield a free flowing dry powder. When this material was treated with formaldehyde and fed to lactating goats (ca. 1 g cyclopropene fatty acids per day), there were substantial increases in the proportions of stearic acid and decreases in the proportions of oleic acid in milk fat. Similar results were obtained when the formaldehyde-treated supplements were fed to lactating cows (ca. 3 g cyclopropene fatty acids per day). The effect was considerably less apparent when theS. foetida seed oilcasein supplement was not treated with formaldehyde, suggesting that cyclopropene fatty acids are hydrogenated in the rumen as are other unsaturated fatty acids. The effect of feeding protected cyclopropene fatty acids on the stearic: oleic ratio in milk fat is probably due to cyclopropene-mediated inhibition of the mammary desaturase enzymes.     

Dimer acid structures. The dehydro-dimer from methyl oleate and Di-t-butyl peroxide

The dehydro-dimer of methyl oleate was prepared and its structure determined as a model of a non-ring dimer for reference in studying the structure of other fatty dimer acids. The dehydro-dimer of methyl oleate is formed by the action of di-t-butyl peroxide on methyl oleate. The reaction is stoichiometric; one mole of DTBP producing one mole of dehydrodimer and two moles of t-BuOH, when excess methyl oleate is used. The dimer was shown to contain two double bonds, and to be formed by carbon-to-carbon linkages predominantly and equally at the 8, 9, 10 and 11 carbons of the oleate monomer segments. Unsaturation was determined by quantitative hydrogenation and far UV absorption. The points of linkage were established by diagnosis of the positions of the involved tertiary carbons of the hydrogenated dimer 1) by chemical oxidation, and 2) by mass spectrometry. Positions of the double bonds were determined by quantitative ozonization, reductive cleavage followed by gas chromatography of the aldehydes and aldehyde esters. Precise molecular weight of the hydrogenated dimer was determined from the parant mass peak at the expected m/e of 594, confirming the non-ring structure. The unhydrogenated dimer showed a parent m/e peak at the expected value of 590. The bridging at the 8 and 10 positions is explained as being due to coupling of radicals with limiting resonance structures resulting from loss of a hydrogen atom from the methylene at position 8. The bridging at the 9 and 11 positions is explained as due to coupling of limiting resonance structures resulting from loss of a hydrogen atom from the methylene at position 11. Mass spectrometric data indicate that the dimerization is a coupling of the expected free radical forms, rather than attack by an oleate free radical on the double bond of an intact oleate molecule, with subsequent loss of hydrogen to form the second double bond in the dimer. Coupling at the 2-position (α to COOCH₃) occurs in not more than 5–10% of the molecules. A small amount of cyclic dimer may be present. Journal Series No. 295. Central Research Laboratories, General Mills, Inc., 2010 E. Hennepin Ave., Minneapolis, Minn. Presented at the AOCS meeting in Atlanta, April, 1963.     

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.     

Chemoenzymatic epoxidation of unsaturated fatty acid esters and plant oils

In the presence of an immobilized lipase fromCandida antacrtica (Novozym 435^R) fatty acids are converted to peroxy acids by the reaction with hydrogen peroxide. In a similar reaction, fatty acid esters are perhydrolyzed to peroxy acids. Unsaturated fatty acid esters subsequently epoxidize themselves, and in this way epoxidized plant oils can be prepared with good yields (rapeseed oil 91%, sunflower oil 88%, linseed oil 80%). The hydrolysis of the plant oil to mono- and diglycerides can be suppressed by the addition of a small amount of free fatty acids. Rapeseed oil methyl ester can also be epoxidized; the conversion of C=C-bonds is 95%, and the composition of the epoxy fatty acid methyl esters corresponds to the composition of the unsaturated methyl esters in the substrate. Based partly on a lecture at the 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995.     

Free radical reactions of peroxidizing lipids with amino acids and proteins: An ESR study

Free radical transfer from oxidizing methyl linoleate to amino acids and proteins was studied in dry model systems incubated for periods up to 20 days. Electron spin resonance was used to study free radical production. Free radicals were detectable in the amino acids lysine, arginine, histidine, tryptophan, and cysteine. Reduced glutathione and, to a limited extent, cystine also gave free radical signals. Free radicals produced in proteins primarily showed central singlet lines, attributable to carbon-centered radicals, with g=2.004±0.001. Sulfhydryl proteins also exhibited downfield shoulders at g≄2.015 and 2.023 that were essentially identical to peaks observed in cysteine and reduced glutathione. The field positions of sulfur resonance in cysteine and proteins suggested a sulfur-oxygen complex rather than thiyl radicals. This report is part of ScD Thesis, MIT, 1974 (KMS).     

Quaternary pyridinium salts from olefins,pyridine and chlorine or bromine

The reaction of olefins with a halogen and pyridine (or pyridine derivative) to form α-haloalkypyridinium quaternary halides has been previously reported only for the halogens bromine and iodine monochloride. In the present study, this reaction has been extended to the use of chlorine as halogen, and to the internal double bonds of unsaturated acids and derivatives. Oleic acid, methyl oleate, methyl linoleate, oleic amide and octadecene were used as olefins. Pyridine, quinoline and γ-picoline were used as the amines. Formation of the quaternaries was shown by chemical and infrared analyses. The reaction occurred rapidly at −20C in excess pyridine as solvent and reagent. The probable mechanism is addition of X⁺ to the double bond to give an α-halo-cation plus halogen anion, followed by attack of the cation by the pyridine to form the quateruary pyridinium cation. The competing reaction of the α-balo-cation with the halo-anion to give the dihalide of the olefin is repressed by the large excess of pyridine used. The quaternary is not formed by reaction of the dihalide with pyridine, since methyl dichlorostearate did not react readily with pyridine. The fatty pyridinium quaternaries show biocidal activity againstE. coli andM. pyogenes. Presented at the Fall AOCS Meeting, Chicago, 1964.