A note on improved isolation of concentrates of linolenic acid and ethyl linolenate from linseed oil

Summary Linolenic acid and ethyl linolenate concentrates (80–85%) have been obtained from linseed oil fatty acids or ethyl esters in 50–60% yield, based on linolenic recovery, by a single urea complex separation at room temperature. This note is IV in the series, “Application of Urea Complexes in the Purification of Fatty Acids, Esters, and Alcohols.” Paper III is reference 6. A laboratory of the Eastern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Cyclic fatty acid yields from linseed oil

Increased yields of saturated cyclic fatty acids which are fluid at −50C have been obtained from linseed oil. Depending on reaction conditions, yields varied from 20–42 g of cyclic acids per 100 g of linseed oil. Solvent ratios of 6, 3, and 1.5∶1; catalyst concentrations of 10, 30, 60, and 100%; and reaction temps of 225, 275, 295, and 325C were evaluated. Ethylene glycol and diethylene glycol were compared as reaction solvents. In general, high solvent ratios favored high cyclic acid yields at the lower reaction temperature, but as the temperature increased the effect of solvent ratio decreased. Increasing the percentage excess of sodium hydroxide increased the cyclic acid yield. Diethylene glycol gave higher yields than ethylene glycol at comparable conditions. Presented at the AOCS meeting in Chicago, Ill., October, 1961. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Methods for improving yields of cyclic acid from linseed oil

Liquid C-18 saturated monocarboxylic acids, which are termed “cylic acids” because they contain a ring structure, have been prepared by the action of excess sodium hydroxide on linseed oil in ethylene glycol at elevated temperatures, followed by distillation and hydrogenation of the resulting free fatty acid monomers and by separation of the straight-chain components by low-temperature crystallization from acetone. In a survey of other possible catalysts and reaction conditions, cyclic acid yields were improved from the previously reported 32.4 g to 43.5 g of cyclic acid per 100 g of linseed fatty acids by removing water from the starting materials and using the monosodium derivative of ethylene glycol as catalyst. The corresponding amount of polymer formed decreased because of a decrease in hydroxylation and subsequent polyester formation. Presented at the AOCS meeting, in Chicago, Ill., 1961. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

The linolenic acid content of peanut oil

Oils prepared from eight peanut cultivars grown in four locations were analyzed for linolenic acid (18:3) content by gas liquid chromatography. Columns packed with either OV 225 or butanediol succinate provided excellent separation of 18:3 from major fatty acids and from trace constituents exhibiting retention times suggestive of 19:0 and 19:1. Average linolenic acid values for cultivars ranged between 0.03 and 0.13 weight percent of total fatty acids.     

Polyunsaturated fatty acid concentrates from borage and linseed oil fatty acids

A modified low-temperature solvent crystallization process was employed for the enrichment of polyunsaturated fatty acids (PUFA) in borage and linseed oil fatty acids. The effects of solvent, operation temperature, and solvent to free fatty acid (FFA) ratio on the concentration of PUFA were investigated. The best results were achieved when a mixture of 30% acetonitrile and 70% acetone was used as the solvent. With an operation temperature of −80°C and a solvent to FFA ratio of 30 mL/g, γ-linolenic acid (GLA) in FFA of saponified borage oil can be raised from 23.4 to 88.9% with a yield of 62.0%. At a yield of 24.9%, α-linolenic acid in linseed oil can be increased from 55.0 to 85.7%. The results of this work are comparable to the best results available in the literature.     

Stability of low linolenic acid canola oil to frying temperatures

The effect of heating on the oxidation of low (1.6%) linolenic acid canola oil (C18∶3) at frying temperature (185 ±5°C) under nitrogen and air was examined and then compared to a laboratory deodorized (9.0%, C18∶3) and a commercially deodorized (8.5%, C18∶3) canola oil sample. A significantly lower development of oxidation was evident for the low C18:3 canola oil, based on the measurement of peroxide value (PV), thiobarbituric acid (TBA), free fatty acids (FFA), dienals and carbonyls. The greater stability of the low C18:3 canola oil was also reflected by a corresponding improvement in heated room odor intensity scores. Heating under nitrogen (rather than air) not only improved the odors but limited the oxidation in all oils. While the low C18:3 canola oil heated under nitrogen was acceptable in 94% of odor judgments the same oil heated in air was acceptable in only 44%. This suggests that even low levels of C18:3 may contribute to the development of the heated room odor phenomenon.     

Cyclic fatty acids from linolenic acid

Linolenic acid of 95% purity was heated with excess alkali in ethylene glycol to produce cyclic fatty acids. Reaction variables, which are associated with the cyclization reaction and which were investigated, included solvent-to-fatty-acid ratio, catalyst concentration, and reaction temperature, headspace gas (N₂ or C₂H₄), and head-space gas pressure. Yields of cyclic acids were improved by increasing solvent ratio (1.5–6 wt basis), reaction temperature (225–295C), and catalyst concentration (10–100% excess). With nitrogen the optimum catalyst concentration was about 100% excess, but when ethylene was used, no increase was obtained beyond 50% excess catalyst. Yields of polymeric acids produced in the reaction generally decreased as cyclic acid yields increased, except in one instance. Higher yields of cyclic fatty acids were obtained with ethylene than with nitrogen under all comparable conditions, and increasing the ethylene pressure to as high as 500 psi improved the yield. Ethylene adds to the conjugated double bonds and is believed to give C₂₀ fatty acids having a 1,4-disubstituted monoene ring in the chain. The maximum yield of monomeric cyclic acids from 95% linolenic acid was 84.6%, the balance being polymeric and unreacted monomeric acids. Monomeric acids from this test contained 95% cyclic acids. Presented at AOCS meeting, New Orleans, 1962. No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Effect of substitution of low linolenic acid soybean oil for hydrogenated soybean oil on fatty acid intake

Low linolenic acid soybean oil (LLSO) has been developed as a substitute for hydrogenated soybean oil to reduce intake of trans FA while improving stability and functionality in processed foods. We assessed the dietary impact of substitution of LLSO for hydrogenated soybean oil (HSBO) used in several food categories. All substitutions were done using an assumption of 100% market penetration. The impact of this substitution on the intake of five FA and trans FA was assessed. Substitution of LLSO for current versions of HSBO resulted in a 45% decrease in intake of trans FA. Impacts on other FA intakes were within the realm of typical dietary intakes. No decrease in intake of α-linolenic acid was associated with the use of LLSO in place of HSBO because LLSO substitutes for HSBO that are already low in α-linolenic acid.     

Polyester amides from linseed oil for protective coatings

The sodium alkoxide-catalyzed reaction of linseed oil or linseed methyl esters with diethanolamine produces almost exclusively linseed diethanolamides. Reaction conditions, e.g., temperature, amount of excess diethanolamine and mode of adding reactants, are reported. The best conditions for producing diethanolamide directly from linseed oil (1 mole) required adding oil to the sodium alkoxide in diethanolamine (6 moles) and heating at 110–115C for 35 min. The linseed diethanolamide isolated in 93–95% yield was an amber oil. Progress of the reaction, followed by thin-layer chromatography, showed only trace amounts of byproducts. Polyester amides were prepared by heating linseed diethanolamide in refluxing xylene with dibasic acids or anhydrides, e.g., azelaic, maleic, fumaric, phthalic, terephthalic, itaconic, brassylic and dimer acids. Molecular weight, viscosity and film properties (air-dried and baked) of the polyester amides were determined. Presented at the AOCS Meeting, Chicago, October 1964. No. Utiliz. Res. Dev. Div., ARS, USDA.     

On-line hydrogenation in GC-MS analysis of cyclic fatty acid monomers isolated from heated linseed oil

A simple on-line hydrogenation method in GC-MS analysis of unsaturated fatty acid esters is described. Using hydrogen as carrier gas, hydrogenation takes place in a capillary reactor connected to the outlet of the analytical column in the oven of the gas chromatograph. The reactor is a fused silica tube (60 cm×0.32 mm i.d.) coated with palladium acetylacetonate. Selective hydrogenation of olefinic bonds is achieved after a normal chromatographic run. Structural information (carbon-skeleton, double bond equivalents) can thus be deduced, and structural correlations between the saturated and unsaturated components can be obtained. Structures of cyclic fatty acid esters isolated from heated linseed oil were elucidated using this simple method which was found very useful for structural investigations on unsaturated compounds by GC-MS. Presented in part at the AOCS meeting in May 1988, in Phoenix, AZ. INRA—Station de Recherches sur la Qualite des Aliments de l'Homme     

Dilution polymerization of linseed oil

Summary An inert diluent, molecularly distilled mineral oil, when present in 90% concentration, permitted, in linseed oil, the polymerization of acyl groups in the absence of inter-glyceride reaction. Comparison of the data for the polymerization of linseed oil in 10, 20, and 100% concentrations showed a marked concentration dependence for the following: polymerization of acyl groups and glyceride molecules; change in specific refraction and the ratio of percentages by weight polymeric acyl groups to polymeric glyceride molecules. N.R.C. No. 3322. Part of this paper was presented at the Protective Coatings Section, Chemical Institute of Canada, Montreal, June, 1952.     

Stand reaction of linseed oil

Several theories have been proposed concerning the stand oil reaction but no precise reaction scheme has been described. In this work, the stand reaction of linseed oil was characterized in order to determine the nature of the products formed during this reaction. Using complementary analytical techniques (more especially NMR and mass spectrometry), the existence of two different reactions was demonstrated: the Diels–Alder addition between fatty acid chains and the addition of a methylene radical on double bonds, followed by combination or elimination reactions.     

Liquid C-18 saturated acids derived from linseed oil

Liquid C-18 saturated monocarboxylic acids that fail to crystallize at −70°C. have been prepared from linseed oil, linolenic acid, and tung oil. Heating one part of linseed oil in three parts of glycol (weight-volume ratio) at 295°C. for 1 hr. with 25% excess sodium hydroxide, followed by distillation and hydrogenation of the resulting free fatty acid monomers and separation of the straight-chain components by low temperature crystallization from acetone, yielded these liquid acids. The relative proportions of cyclic acids, straight-chain monomeric acids, and polymer varied with the type of starting material and with the conditions employed. Cyclic acids in excess of 30% yields were obtained from linseed oil. Some hydroxylation of the fatty acids apparently takes place during cyclization; the amount increases with ascending temperatures, as evidenced by a rise in polyester content of the polymer fraction. Evidence indicates that the bulk of the unhydrogenated cyclic acids are vicinal disubstituted cyclohexadienes. Gas chromatography of the cyclic acids hydrogenated to an iodine value <1 shows that there are several components. These have not as yet been separated and positively identified. Presented at fall meeting, American Oil Chemists' Society, New York, N.Y., October 17–19, 1960. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

过氧化氢一步法制备环氧亚麻油工艺

报道了亚麻油在以石油醚为溶剂、磷酸为催化剂的条件下,经甲酸、双氧水环氧化,一步合成增塑剂——环氧亚麻油的一种新方法。该法反应条件温和,操作方法简单,反应时间较短,而且产物各项指标均可达到增塑剂标准：环氧值＞7.8,碘值＜10,酸值＜0.5。     

Determination of conjugated linolenic acid content of selected oil seeds grown in Turkey

Seeds originating from some Turkish sources were analyzed with respect to their characteristics and FA compositions. These seeds represented pomegranate (Punica granatum L.), bitter grourd (Momordica charantia L.), pot marigold (Calendula officinalis L.), catalpa (Catalpa bignonoides), bourdaine (Rhamnus frangula L.), Oregon grape (Mahonia aquifolium), sarsaparilla (Smilax aspera), mahaleb (Prunus mahaleb L.), black-thorn (Prunus spinosa L.), cherry laurel (Prunus laurocerasus L.), and firethorn (Pyracantha coccinea). Bitter gourd and bourdaine seeds contain more than 20% oil. Catalpa, bourdaine, Oregon grape, blackthorn, and cherry laurel seed oil contents ranged from 15 to 20%. In the seeds from plants belonging to the Rosacea family, oil content ranged from 4.5 to 18.5%. Among the seed oils analyzed, pot marigold had one of the lowest oil contents (5.9%). Pomegranate contained the highest amount of total conjugated linolenic acid (CLNA) (86.0%). Seed oils of bitter grourd, pot marigold, mahaleb, and catalpa were rich in CLNA: 60.0, 29.5, 27.6, and 27.5%, respectively. Bourdaine, Oregon grape, and sarsaparilla seeds contained low amounts of CLNA. On the other hand, mahaleb, bourdaine, catalpa, Oregon grape, sarsaparilla, cherry laurel, blackthorn, and firethorn seed oils are basically oleic and linoleic acid-rich oils and therefore have little drying ability (semidrying oil). The results show a potential for the use of endogenous Turkish seeds as a source of CLNA.