Estolide production with modified clay catalysts and process conditions

The 20% yields of estolides prepared from oleic acid and meadowfoam oil fatty acids are improved when the montmorillonite clay catalysts are modified to increase their activity. Changes we explored included acidifying the clay, treating to increase the surface area of clay to introduce new active sites, and decreasing the ionic character of the clay surface to enhance adsorption of the fatty acids. We also evaluated the use of higher levels of clay in the reactions. Clays treated with Fe³⁺ salts increase the estolide yield from 21 to 27%, a 28% increase. Clay catalysts were also treated with surface-active reagents. The most active were cationic surfactants, and montmorillonite clays treated with cetyltrimethylammonium chloride increased the estolide yield to 30%. Estolide yields could not be improved beyond 30% by increasing the amount of clay. However, nitrogen sparging increases the efficiency of stirring and increased the estolide yield to 35% estolide.     

Biodegradation of estolides from monounsaturated fatty acids

Mono- and polyestolides, made from oleic acid, meadowfoam oil fatty acids and erucic acid, were subjected to biodegradation with mixed cultures of Penicillium verucosum, Mucor racemosus, and Enterobacter aerogenes. Fermentations were continued for 3, 5, 10, 15, 20, or 30 d. Meadowfoam oil and its fatty acids, oleic acid and soybean oil were also biodegraded under the same conditions. After 10 d, oleic acid and soybean oil were degraded 99.8 and 99.2%, respectively; meadowfoam oil and its fatty acids were degraded 89.0 and 97.7%, respectively. After 30 d, oleic acid-derived poly- and monoestolides were degraded 98.6 and 90.0%, respectively, meadowfoam estolides were degraded 75.7%, and erucic acid estolides were degraded 84.0%.     

Quantitation of estolides by Fourier transform infrared spectroscopy

Estolides were produced from meadowfoam oil fatty acids, oleic, linoleic, petroselinic, andcis-5,cis-13 docosadienoic acids. Estolide reaction mixtures were quantitated by Fourier transform infrared spectroscopy and compared to the area percentages determined by high-performance liquid chromatography. The absorbance frequency of estolide carbonyl (1737 cm⁻¹) is different than the lactone carbonyl (1790 cm⁻¹) and the acid carbonyl (1712 cm⁻¹). Estolide standards were obtained by wiped-film molecular-still distillations and column chromatography.     

Estolides from meadowfoam oil fatty acids and other monounsaturated fatty acids

The formation of estolides was detected during the studies on dimerization of meadowfoam oil fatty acids. By adjusting the reaction conditions, it was possible to produce monoestolides with little dimer or trimer formations. Estolides have potential use in lubricant, cosmetic and ink formulations and in plasticizers. This paper reports the conditions for production of estolides from mixed meadow-foam fatty acids, commercial oleic acid, high-oleic sun-flower oil fatty acids,cis-5,cis-13-docosadienoic acid, petroselinic acid and linoleic acid.     

Pelargonic acid in enhanced oil recovery

Oxidation of monounsaturated fatty acids, such as erucic and oleic acids, results in the formation of dibasic fatty acids, such as brassylic and azelaic acids. Dibasic acids find many industrial applications. Pelargonic acid is the co-product of the process. Expanded use of dibasic acids would require an expansion in the existing and possibly new uses for pelargonic acid and its derivatives. In this study, the potential for using pelargonic acid in enhanced oil recovery is investigated. Experimental results are presented for the enhanced oil recovery by waterflooding with the aid of a surfactant.In situ formation of surfactant at the oil-water interface vs. the formation of surfactant in the floodwater prior to injection is examined.     

Mineral acid-catalyzed condensation of meadowfoam fatty acids into estolides

Meadowfoam fatty acids (83% monoenoic fatty acid), reacted with 0.01–0.1 mole equivalents of perchloric acid, gave 33–71% yield of estolide, an oligomeric 2° ester, resulting from self condensation. Equimolar amounts of perchloric acid to fatty acid failed to produce estolide but converted the fatty acids to a mixture of lactones, mainly γ-eicosanolactone. Temperature plays a critical role; higher temperatures (75–100°C), at the same acid concentration, provide lactones while lower temperatures (20–65°C) yield estolides. Lower acid levels (<0.1 mole equivalents) gave the best yields (≈70%) at 65°C. The estolide and monomer were characterized by nuclear magnetic resonance, infrared high-pressure liquid chromatography, gas chromatography, gas chromatography/mass spectrometry. The estolide is a mixture of oligomers with an average distribution near 1.65 ester units. The ester linkages are located mainly at the original double bond positions but have some positional isomerization to adjacent sites in accord with carbocation migration along the alkyl chain. The residual double bond of the estolide was extensively isomerized fromcis totrans and positionally along the chain. The distilled monomer is similar in structure to the unsaturated portion of the estolide with geometrical and positional double bond isomerization. In addition, a significant amount of cyclization of the fatty acids to lactone (≈30%) had occurred.     

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.     

Synthesis of estolide esters from cis-9-octadecenoic acid estolides

Oleic acid (cis-9-octadecenoic acid) was converted in excellent yield to the estolide, which was then esterified with 2,2-dimethypropan-1-ol (neopentyl alcohol), cis-9-octadence-1-ol (oleyl alcohol), and 2-propanol to generate the corresponding estolide esters. Higher-formula mass estolide esters were synthesized by reaction of the parent estolide with 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 1,5-pentanediol to give the corresponding diesters of oleic estolide, thus doubling the molecular size of the parent estolide. Pour points and viscosities were determined in order to evaluate these products for possible industrial application.     

Biodiesel preparation in a batch emulsification reactor

The transesterification of vegetable oils (rapeseed oil was used here) by low molecular weight alcohol is the most used method of biodiesel production. Since the reaction proceeds at the alcohol‐oil interface, it is necessary to create a large interphase surface area using a special emulsifying attachment. We studied how the conditions (e.g., independent variables: molar ratio alcohol to oil, amount of catalyst used, KOH, time and temperature of reaction, intensity of stirring, revolution of emulsifying attachment) affected the quality and quantity (dependent variables) of the ester phase, i.e., the biodiesel. The amount of used catalyst was calculated with respect to the content of free fatty acid in the oil. The statistical system of Plackett‐Burman was used for experiment planning. The relationship between independent and dependent variables was determined and described by multidimensional linear regression. Various statistical tests (principal component analysis, correlation matrix) were also performed.     

Fatigue behaviour of multiblock thermoplastic elastomers. 3. Stepwise increasing strain test of poly(aliphatic/aromatic-ester) copolymers

The fatigue behaviour of poly(aliphatic/aromatic-ester) (PED) multiblock copolymers has been evaluated using the hysteresis loop method. Stepwise increasing strain test (SIST) was performed at a frequency of 1 Hz. The strain levels were varied with increasing extension steps: 3, 5, 10, 15, 20, 25 and 30% of the initial strain, while minimum stress has been set at a constant value of 0.1 MPa. It has been found that soft PEDs show a very good stress relaxation due to the fact that they contain high amounts of the amorphous phase and their soft segments do not crystallize. PED copolymers, especially those containing low amounts of crystalline hard domains showed very good damping properties at small strain levels. It has also been found that PED's ability to store and dissipate energy is a function of the hard segment concentration. This method proved to be a useful tool for determining the changes in the material properties of PEDs and other thermoplastic elastomers during deformation.     

Characterization of monomers produced from thermal high-pressure conversion of meadowfoam and oleic acids into estolides

The monomers produced from thermal high-pressure conversion of meadowfoam or oleic acids into estolides were characterized as a complex mixture of fatty acids. Mild reaction conditions produced little change in the starting acids. However, vigorous reaction conditions,e.g. ≥3 h at 250°C with stirring, significantly altered the starting fatty acids.Cis/trans isomerization occurred readily, with the proportion oftrans isomers reaching 57%. In addition, the double bonds migrated throughout all positions of the hydrocarbon chain with concentrations diminishing outward from the starting double bond position. Branching was also observed to a small extent under these conditions and was even more pronounced in the absence of water. Lactones were also identified in the reaction mixture, with contents near 16% in the meadowfoam series. All products can be explainedvia carbocation rearrangement mechanisms that result from protonation of the starting olefins.     

Synthesis of secondary ethers derived from meadowfoam oil

Secondary ethers can be obtained from meadow-foam-derived delta lactones or 5-hydroxy fatty acids by using Lewis or Brønsted acid catalysts in good yield (70–90%). The conversion of δ-lactone or 5-hydroxy fatty acid to 5-ethers is performed under atmospheric pressure between 67 and 125°C with 0.5–6.4 mole equivalents of acid catalyst in the presence of 2–40 equivalents of alcohol and a reaction time of 1–140 h. Acid catalysts include mineral acids, such as perchloric and sulfuric; Lewis acids, such as boron trifluoride; and heterogeneous catalysts, such as clays and ion-exchange resins. Primary alcohols, such as methanol, butanol, decanol, and oleyl alcohol, or branched-chain alcohols, such as 2-ethylhexanol, can be used to make secondary ether fatty esters. The 5-ether fatty esters and the process for their formation have not been previously known and appear to be limited to structures where stabilized cations can be formed. The novel ethers were fully characterized by nuclear magnetic resonance and gas chromatography-mass spectrometry.     

Fatigue behaviour of multiblock thermoplastic elastomers. 1. Stepwise increasing load testing of poly(aliphatic/aromatic-ester) copolymers

Fatigue properties of poly(aliphatic/aromatic-ester) (PED) multiblock copolymers were evaluated based on the hysteresis measurement method. This method allows the digitalization of the hysteresis loop and beside the determination of stress and strain-related parameters, stored energy, lost energy, damping and dynamic creep behaviour can be determined. The correlation between hard/soft segment concentration of PED copolymers, and fundamental parameters, which derived during the cyclic loading (using stepwise increasing load testing, SILT), has indicated a good load-carrying performance of polymers containing a high amount of the hard phase. PED copolymers compare very well with commercially available poly(ester-ethers) and show a much better performance than poly(ester-urethanes) when samples are loaded at the same fatigue stress level relative to their ultimate tensile strength. Softer PEDs and poly(ether-urethane) copolymer show much higher values of dynamic modulus than chemically cross-linked silicone elastomer. Therefore, these multiblock copolymers can be considered as good candidates for applications where materials are subjected to oscillatory deformations (for example passive flexor tendon reconstruction).     

The fatty acid composition of lipids from muscle and adipose tissues of pigs fed various oil mixtures differing in their ratio between oleic acid and linoleic acid

High concentrations of polyunsaturated fatty acids (PUFA) in meat have detrimental effects on its technical properties. The present study was carried out to investigate whether PUFA levels in pork can be reduced by increasing the concentrations of oleic acid in pig diets. To this end a bifactorial experiment was carried out with 48 female growing finishing pigs. Six different diets were used with two different concentrations of linoleic acid (12 vs. 24 g/kg) and three different concentrations of oleic acid (12 vs. 18 vs. 24 g/kg). The experiment started at a body weight (BW) of 58 kg and continued until 115 kg BW. The fatty acid composition of total lipids of backfat, perirenal fat and musculus (m.) longissimus dorsi was analysed. Concentrations of linoleic acid and total PUFA in backfat and perirenal fat were affected only by the dietary linoleic acid content but not at all by the dietary oleic acid content. Increasing the dietary concentration of oleic acid raised the level of oleic acid in those tissues at the expense of saturated fatty acids, suggesting competition between monounsaturated fatty acids and saturated fatty acids for incorporation into triglycerides. At the low dietary linoleic acid concentration, the percentages of linoleic acid and total PUFA in total lipids of m. longissimus dorsi were also unaffected by the dietary oleic acid content. In contrast, at the high dietary linoleic acid concentration, percentages of linoleic acid and total PUFA of the m. longissimus dorsi were reduced by increasing the dietary concentration of oleic acid, suggesting that oleic acid and linoleic acid compete for incorporation into muscle lipids. Thus, at high dietary linoleic acid levels the fatty acid composition of the m. longissimus dorsi was favourably affected by high dietary oleic acid concentrations; in backfat and perirenal fat, however, no beneficial effect of high dietary oleic acid levels was seen.     

Kinetics of palm oil transesterification in a batch reactor

Methyl esters were produced by transesterification of palm oil with methanol in the presence of a catalyst (KOH). The rate of transesterification in a batch reactor increased with temperature up to 60°C. Higher temperatures did not reduce the time to reach maximal conversion. The conversion of triglycerides (TG), diglycerides (DG), and monoglycerides (MG) appeared to be second order up to 30 min of reaction time. Reaction rate constants for TG, DG, and MG hydrolysis reactions were 0.018–0.191 (wt%·min)⁻¹, and were higher at higher temperatures and higher for the MG reaction than for TG hydrolysis. Activation energies were 14.7, 14.2, and 6.4 kcal/mol for the TG, DG, and MG hydrolysis reactions, respectively. The optimal catalyst concentration was 1% KOH.     

The Interaction of the Soybean Seed High Oleic Acid Oil Trait With Other Fatty Acid Modifications

Oil value is determined by the functional qualities imparted from the fatty acid profile. Soybean oil historically had excellent use in foods and industry; the need to increase the stability of the oil without negative health consequences has led to a decline in soybean oil use. One solution to make the oil stable is to have high oleic acid (>70%) and lower linolenic acid content in the oil. Other fatty acid profile changes are intended to target market needs: low‐saturated fatty acid and high stearic acid content in the oil. The objective of this study is to determine the interaction of the high oleic acid oil trait with other alleles controlling fatty acid profiles. Soybean lines containing high oleic acid allele combinations plus other fatty acid modifying alleles were produced, and the seed was produced in multiple field environments over 2 years. Stable high oleic acid with low linolenic acid (<3.0%) was achieved with a 4‐allele combination. The target of >20% stearic acid in the seed oil was not achieved. Reducing total saturated fatty acids below 7% in a high oleic acid background was possible with mutant alleles of both an acyl‐ACP thioesterase B and a β‐ketoacyl‐[acyl‐carrier‐protein] synthase III gene. The results identified allele combinations that met the target fatty acid profile thresholds and were most stable across environments.     

Acid-catalyzed condensation of oleic acid into estolides and polyestolides

Oleic acid, when treated with 1.0 equivalent of perchloric acid at 50°C, produced a 76% yield of polyestolide. The concentration of mineral acid greatly affected the rate of estolide formation, with increased rates under high acid concentrations. Over a range of temperatures from room temperature to 100°C, reaction rates increased at higher temperatures. However, high acid concentrations and temperatures produced undesirable side products, primarily lactones. Other acids catalyze the condensation of oleic acid to form estolide with the following relative rates: HClO₄ >H₂SO₄>p-toluenesulfonic>BF₃·Et₂O> montmorillonite K-10>HCl>H₃PO₄, HNO₃. Addition of water impedes the formation of estolide.     

Ultrasonicvs. nonultrasonic hydrogenation in a batch reactor

Refined and bleached soybean oil was hydrogenated with and without ultrasonic energy in a batch system. Reactions were carried out at 170°C with 0.02% nickel catalyst (Nysel, Harshaw/Filtron Partnership, Cleveland, OH) or 50 ppm nickel in the oil. Hydrogen pressure was varied from 15 to 90 psig. After 20 min, the average reaction rate was about five times faster in the presence of ultrasonic energy. Hydrogenation rate generally increased with increasing hydrogen pressure when ultrasonic energy was applied. However, the increasing rate is more sinusoidal in nature than linear.     

A gas chromatography–mass spectrometry method for the detection of chlorpyrifos contamination in palm-based fatty acids

Chlorpyrifos is a Malaysian Pesticide Board-approved organophosphate insecticide, which may become concentrated during fractionation. The objective of this project was to develop and validate a method to detect and quantify chlorpyrifos in food-grade fatty acids ingredients, e.g. caprylic-capric acid mixture and oleic acid (OLA) used to synthesize triacylglyceride based food additives and in the cosmetic industry. A selective ion monitoring gas chromatography–mass spectrometry method with a matrix-matched calibration curve calibration was selected. The method involved the direct injection of chlorpyrifos spiked into the fatty acids matrix. The percentage recoveries at spiking levels of 0.5, 0.75, 2.5, and 4.0 μg g⁻¹ of chlorpyrifos in OLA and caprylic-capric acid ranged from 85.7%–101.1% to 97.2%–112%, respectively, with a relative standard deviation of within 11%. The intra-day and inter-day precision were deemed acceptable as indicated by an relative SD value of within 10%. A good linear relationship with a coefficient of correlation >0.99 for the matrix-matched calibration was achieved between 0.5 and 5 μg g⁻¹. The limit of detection and limit of quantification corresponded to 0.5 μg g⁻¹ for OLA and 0.55 μg g⁻¹ for caprylic-capric acid.