Unsaturated Fatty Acid Esters Research Articles

Biodiesel and hydrodeoxygenated biodiesel autothermal reforming over Rh-containing structured catalyst

In this study, new results of comparative research on autothermal reforming(ATR) of biofuels (hydrodeoxygenated biodiesel and long- stored biodiesel) over composite RhSC catalysts (0.24 wt.% Rh supported on structured Ce0.75Zr0.25O2-δ-ƞ-Al2O3/FeCrAl carrier) were obtained. The impact of fuel chemical composition on the catalyst performance was discussed. Hydrodeoxygenated biodiesel mainly consisted of heptadecane, other normal alkanes and small amounts of alkenes together with a portion of unreacted fatty acid ethers. RhSC exhibited syngas productivity of about 2.5 m3Lcat−1 h−1 (STP) at complete conversion of hydrodeoxygenated biodiesel without considerable by-products formation, at molar ratios O2/C = 0.54, H2O/C = 3, T =750 °C and GHSV =5000 h−1. The catalyst exhibited stable operation and no coke formation for at least 90 h on stream.Biodiesel after nine years storage, which was used in this study, contained methyl esters of saturated and unsaturated fatty acids and a large proportion of polymeric compounds. It was successfully demonstrated that even this aged biodiesel can be converted to synthesis gas over the developed Rh/Ce0.75Zr0.25O2-δ-ƞ-Al2O3/FeCrAl structured catalyst. Further optimization of the catalyst and reaction conditions (higher temperature, lower GHSV, catalyst doping by promoters) is required for reaching efficient reforming of the aged biodiesel. Nevertheless, it was demonstrated that biodiesel and hydrodeoxygenated biodiesel, which combine high energy density and renewability, were very attractive biofuels for fuel cell-based power unit applications.

Epoxidation of Vegetable Oils, Unsaturated Fatty Acids and Fatty Acid Esters: A Review

A comprehensive review of recent existing methods of epoxidation of vegetable oils, unsaturated fatty acids and alkyl esters of unsaturated fatty acids has been presented. The importance of epoxidized vegetable oils and their applications in the production of polyols and polyurethanes was discussed. Interests of researchers have been mainly focused on the development of advantageous technological parameters of vegetable oils epoxidation. The epoxidations with peracetic acid or performic acid generated in situ were mainly performed in the presence of strongly acidic catalysts. The influence of process variables such as temperature, stirring speed, the molar ratio of carboxylic acid and hydrogen peroxide to the amount of ethylenic unsaturation, amount of catalyst and reaction time on the course of epoxidation has been investigated.

RESEARCH ON LUBRICATION PROPERTIES OF SELECTED RAW PLANT AND ANIMAL MATERIALS

The article presents the results of research on lubrication properties of rapeseed oil, methyl esters of rapeseed oil, as well as esters with goose fat. Rapeseed oil has a better lubrication properties in relation to methyl esters of rapeseed oil. Addition of goose fat to esters negatively affected their lubrication properties. The presented results confirm a relationship between the degree of unsaturated and lubricated properties. Among the tested compounds with oxygen groups (COOH, COOCH3, C = O), the oleic acid (with a COOH group) characterised the best lubricity. The fat goose, which contains the least amount of unsaturated fatty acid esters, proved to be ineffective addition lubricity between the factor lubricants analysis.

Sustaining the Oxidation Stability of Biodiesel and Its Blends in Plug-in Hybrid Vehicles Using Adsorbents

This study investigates the impact of adsorbents on the oxidation stability of biodiesel and its blends. Biodiesel fuels contain significant amounts of unsaturated fatty acid esters and therefore, ...

Physical–chemical investigation of the oxidation reaction of biodiesel during storage in contact with carbon steel and 1020 steel in the presence of natural rosemary extract

Biodiesel is a renewable fuel derived from oilseeds or animal fats. Biofuel has low oxidative stability due to the high content of esters of unsaturated fatty acids, which are easily oxidized when exposed to air, light, heat and metals. Antioxidants are added to biodiesel to retard the oxidative process, which can capture free radicals making them thermodynamically more stable. This study aims to analyze the oxidative stability of biodiesel in the presence of metallic alloys of carbon steel and 1020 steel with the presence of rosemary extract. The rosemary extract had a phenol content of of 25,579 mgEAG/gdry mass, acting as antioxidant. In the presence of the natural rosemary extract, the biodiesel samples with metallic alloys but without rosemary extract presented similar oxidative stability and physicochemical properties, but when the rosemary extract is present, the carbon steel alloy presented a considerable compatibility, reaching higher induction periods. The thermodynamic parameters of the biodiesel sample with carbon steel and natural rosemary extract showed a significant improvement with the addition of antioxidant.

Antioxidant, Cytotoxicity, and Antiophidian Potential of Alstonia macrophylla Bark.

The objective of this research was to find the possible pharmacognosy of the bark of the Philippine Alstonia macrophylla Wall. ex G.Don (AM). Gas chromatographic–mass spectral (GC–EI-MS) characterization and energy dispersive X-ray spectroscopy (EDX) were performed to detect the bioactive constituents. EDX analysis of AM bark displayed a high content of potassium (3.26%) and calcium (2.96%). Eight constituents were detected in AM crude dichloromethane (DCM) extracts, which consisted of a long-chain unsaturated fatty acid (17:0) and fatty acid esters such as ethyl hexadecanoate and methyl hexadecanoate. Extraction of AM bark using methanol and dimethyl sulfoxide (MeOH/DMSO) solvents resulted in the identification of 17 constituents, principally alkaloids (alstonerine, 34.38%; strictamin, 5.23%; rauvomitin, 4.29%; and brucine, 3.66%) and triterpenoids (γ-sitosterol, 3.85%; lupeol, 3.00%; 24-methylenecycloartanol, 2.81%; campesterol, 2.71%; β-amyrin, 2.30%; and stigmasterol, 2.13%). MeOH/DMSO samples of AM were used in the selected bioassays. The samples exhibited efficient free radical scavenging activity (IC50 = 0.71 mg/mL) and were noncytotoxic to normal HDFn (IC50 > 100 μg/mL) and neoplastic THP-1 cell lines (IC50 = 67.22 μg/mL) while highly degenerative to MCF-7 (IC50 = 6.34 μg/mL), H69PR (IC50 = 7.05 μg/mL), and HT-29 (IC50 = 9.10 μg/mL). Most interestingly, the AM samples inhibited the northern Philippine Cobra’s (Naja philippinensis Taylor) venom (IC50 = 297.27 ± 9.33 μg/mL) through a secretory phospholipase A2 assay.

Preparation of partial crystalline mesoporous zeolite TS-1 for epoxidation of unsaturated fatty acid ester

Abstract Amorphous Ti-MCM-41 with/without cetyltrimethylammonium template could be crystallized into TS-1 zeolite by way of solid state crystallization with steam assisted conversion (SAC) method. The crystallinity with changing textural property of the SAC crystallized product could be controlled by the composition of mesoporous material and SAC processing time. The partial crystallized zeolite (PCZ) material showed much better catalytic performance in epoxidation of unsaturated fatty acid ester than either Ti-MCM-41 or TS-1, which is attributed to synergistic effect of enhanced crystallinity and retention of mesopore in PCZ. The optimum reaction condition was to use TBHP oxidant in using ethylacetate and acetonitrile solvent superior to the H2O2 oxidant in protic solvent.

Physical and chemical effects of biodiesel storage on high-density polyethylene: Evidence of co-oxidation

The physical and chemical effects of diesel and biodiesel fuels on two high-density polyethylene (PE-HD) types were investigated. Both semi-crystalline PE-HD are common thermoplastic materials for container and storage tank applications. Biodiesel, a composition of unsaturated fatty acid esters from renewable resources, was chosen as it is regarded a possible green alternative to fossil fuels. The study aims at identifying significant differences between biodiesel and conventional diesel fuels based on the differences in the chemical nature of the two.The physical effects of the fuels on the polymer at first comprises the sorption behavior, i.e. kinetics and final equilibrium concentration. Not only are both fuels absorbed by the amorphous phase of the semi-crystalline PE-HD, they also induce a plasticization effect that modifies the molecular mobility and therefore also the characteristic yielding properties, manifest in the obtained stress-strain curves.The chemical effects related to degradation phenomena is investigated by a long-term storage scenario using partially immersed tensile test specimens in diesel and biodiesel. We were able to confirm the proposed co-oxidation mechanism by Richaud et al. for polyethylene-unsaturated penetrant systems on a larger scale based on practical tensile tests. One of the investigated polyethylene grades subjected to tensile drawing showed a significant loss of plastic deformation and the onset of premature failure after 150 days of storage in biodiesel. Further biodiesel storage showed a systematically reduced elongation at break before necking. None of these effects were observed in diesel. Oxidation of fuels and polymer after progressing storage times were analyzed by the evolution of carbonyl species in FT-IR/ATR spectroscopy.

Kinetic and thermodynamic parameters in biodiesel oxidation reaction in the presence of coffee leaves and sage extracts

The biodiesel obtained from soybean oil consists mainly of esters of unsaturated fatty acids which gives it low oxidative stability. In order to inhibit the oxidative reactions, extracts of arabica coffee leaves and sage were added to the biodiesel. The induction period, the kinetic and thermodynamic parameters were determined using the Rancimat method at temperatures 110, 115, 120 and 125 °C. The results of induction periods containing sage extract and coffee leaves were 7.30 and 6.86 h, respectively, higher values than that obtained for biodiesel without addition of antioxidant species. Among the thermodynamic parameters it was observed that the activation entropy was negative (ΔS‡ < 0) for all the tests indicating the formation of activated complexes. The values of free energy of Gibbs indicated the increase of the energy necessary for the biodiesel to oxidize when in the presence of extracts of sage and coffee leaves, isolated or in mixture, which proves its efficiency as antioxidant agents.

One‐Pot Catalytic Copolymerization of Unsaturated Plant Oils or Fatty Acid Methyl Esters with Ethylene

Until now natural fatty acid esters with their internal CC‐bonds cannot be used as substrates for catalytic polymerization reactions. It is always necessary to convert them to terminal unsaturated fatty acid esters first. Therefore, we now developed a two‐catalyst system consisting of an isomerization catalyst and a Brookhart polymerization catalyst. With this system of isomerizing copolymerization (IsoCoP) it is possible to copolymerize high oleic plant oils or fatty acid methyl esters with ethylene in a one‐pot reaction. The resulting polymers have molecular weights above 30 kDa and can contain more than 20 weight percent plant oils. The copolymers of fatty acid methyl esters are soluble in organic solvents. The predominant part of the copolymers from plant oils is usually soluble. The insoluble fraction is soluble after hydrolysis indicating a rare cross‐linking of polyolefin chains by triglycerol units. The catalytic system is effective yielding polymers with a productivity of up to 100 kg polymer per mole catalyst and pretty robust. Plants oils need to be purified only by a simple filtration over alumina before copolymerization.Practical Application: The possibility to copolymerize plant oils with ethylene leads to a new class of polymers and may enhance the usage of plant oils for plastics greatly. The new polymers might be used, e.g., for tackifiers or primers.High oleic plant oils as well as unsaturated fatty acid methyl esters can be directly copolymerized with ethylene by a combination of an isomerization catalyst with a Brookhart polymerization catalyst.

Phenolic compounds obtained from alkyl oleates as additives to improve the oxidative stability of methyl rapeseed biodiesel

Phenolic antioxidants have limited solubility in biodiesel, so this research developed new antioxidants by addition of hydroquinone and catechol on unsaturated fatty acid esters, which improved significantly the oxidative stability of rapeseed biodiesel. This new compound class is more soluble in biodiesel than hydroquinone and catechol, in same molar concentrations. The aging of biodiesel was studied using Metrohm model 743 Rancimat and PetroOxy devices and it was possible to observe an improvement on oxidation stability in both testing using these new antioxidants. Especially the additives 2MB3 and 4MB3 improved the induction period (IP) of rapeseed methyl ester (RME‐B100), from 4 to 63 and 65 h, respectively, with 30 mmol/kg of additives, while hydroquinone in comparison improves the stability to 25 h in the same molar concentration. This new class of antioxidants is promising to enhance oxidative stability of biodiesel, showing the capability of such additives to be commercialized for this purpose.Practical applications: Biodiesel is obtained by different raw materials, so the composition is different according to the source. The biodiesel with higher amounts of unsaturated fatty acids is more susceptible to oxidation than those with higher saturation. To solve problems caused by oxidative deterioration of biodiesel, this research aimed to synthesize a new class of antioxidants as an alternative for preventing and minimize oxidative damage of biofuels.Rapeseed biodiesel without any addition of additive was out of specification according to EN 14214, which regulates oxidative stability greater or equal to 8 h. The additives herein obtained improved significantly the oxidation stability for rapeseed biodiesel by more than 100%.

First isomerizing copolymerization of natural unsaturated fatty acid esters with α‐olefins

First isomerizing copolymerization of natural unsaturated fatty acid esters with <i>α</i>‐olefins

Apparent activation energy and relative protection factor of natural antioxidants in mixture with biodiesel

ABSTRACTIn Brazil, biodiesel mainly consists of unsaturated fatty acid esters, which gives low oxidative stability. Therefore, natural antioxidants present themselves as an alternative to prevent oxidative deterioration due to the presence of phenolic compounds in their structure, capable of inhibiting free radicals by donating hydrogen atoms. Extracts of pepper, bacupari leaves, coffee leaves and sage were added to biodiesel B100 to verify the efficiency of antioxidant on the oxidation reaction of biodiesel, using as a parameter the comparative relative protection factor (RPF). Linearity deviations were observed in the graph of the logarithm of the rate constant as a function of the inverse of temperature, indicating that the activation energy varies at the different temperatures 110, 115, 120 and 125°C of the accelerated Rancimat test. The RPF analyzed by the simplex-centroid design proved to be a suitable parameter to verify the efficiency of natural antioxidants in the protection of the oxidation reaction, indicating an optimized mixture of 25% pepper, 60% coffee leaves and 15% sage.

Exploring unsaturated fatty acid cholesteryl esters as transdermal permeation enhancers.

The intrinsic protective barrier property of skin, one of the major challenges in the design of transdermal drug delivery systems, can be overcome through the use of chemical permeation enhancers (CPEs). Herein, we explore the potential of unsaturated fatty acid (UFA) esters of cholesterol (Chol) viz., oleate, linoleate and linolenate, as transdermal CPEs using tenofovir (TNF) as a model drug. All Chol UFA esters at 1% w/w were found to be more effective enhancers when compared to their respective parent fatty acids (FAs) and saturated FA counterparts. Cholesteryl linolenate (Chol-LLA) showed the most superior performance (enhancement ratio (ER)=3.71). The greatest ER for Chol-LLA (5.93) was achieved at a concentration of 2% w/w. The histomorphological and transepithelial electrical resistance (TEER) evaluations supported the results of the permeability studies. These findings showed no significant loss in the integrity of the epidermis, with drug and enhancer treatment having temporary effects on the barrier property of the epidermis. Chol UFA esters can therefore be considered as new CPEs for exploitation in topical formulations for various classes of drugs.

Total phenolics and flavonoids content, antioxidant activity and GC/MS analyses of Euphorbia grandialata

Objective: This study has been designed to study phenolic and flavonoid contents quantitatively; screen antioxidant activity and investigate unsaponifiable and saponifiable matters of Euphorbia grandialata R. aerial parts. Methods: Total phenolic and flavonoid content were determined by Folin-Ciocalteu reagent and aluminium chloride methods respectively, while 2, 2-diphenyl-1-picrylhydrazyl (DPPH) was used for anti-oxidant assay. GC/MS analysis was used to analyse unsaponifiable and saponifiable matters. Results: Total phenolics result was calculated as (17.61 ± 1.2 μg gallic acid /g), total flavonoids as (4.495 ± 0.39 μg rutin/g) and anti-oxidants activity as (140.6 % μg ascorbic acid/g). The identified compounds in unsaponifiable matter were hydrocarbons (51.1 %), steroids and triterpenes (35.92%). The saponifiable matter showed fourteen components from which six were identified as methyl esters of saturated fatty acids (46.26%) and eight as methyl esters of unsaturated fatty acids (53.74 %). Conclusion: Euphorbia grandialata could be considered as a valuable source of natural antioxidants. This is the first report for phenolics and flavonoids content, antioxidant activity and GC/MS analysis of this plant.

Castor oil as a potential renewable resource for the production of functional materials

Castor oil is increasingly becoming an important bio-based raw material for industrial applications. The oil is non-edible and can be extracted from castor seeds from the castor plant belonging to the family Euphorbiaceae. The oil is a mixture of saturated and unsaturated fatty acid esters linked to a glycerol. The presence of hydroxyl group, a double bond, carboxylic group and a long chain hydrocarbon in ricinoleic acid (a major component of the oil), offer several possibilities of transforming it into variety of materials. The oil is thus a potential alternative to petroleum-based starting chemicals for the production of materials with variety of properties. Despite this huge potential, very little has recently been reviewed on the use of castor oil as a bio-resource in the production of functional materials. This review therefore highlights the potential of castor oil in the production of these diverse materials with their projected global market potential. The review gives the background information of castor oil and its geographical availability, the properties and its uses as bio-based resource for synthesis of various materials. The review further highlights on the use of castor oil or ricinoleic acid as a green capping agent in the synthesis of nanomaterials.

Enzymatic synthesis and anti-oxidative activities of plant oil-based ascorbyl esters in 2-methyltetrahydrofuran-containing mixtures

Ascorbyl fatty acid esters are commercially interesting fat-soluble antioxidants. In this work, enzymatic synthesis of ascorbyl esters from less expensive and readily available plant oils, and their anti-oxidative activities are described. Among the immobilized lipases tested, Candida antarctica lipase B was the best for the synthesis of plant oil-based ascorbyl esters. The enzyme showed much better catalytic performances in the binary mixtures of biomass-based 2-methyltetrahydrofuran (MeTHF) and t-butanol than the previously preferred t-butanol. The conversions of 70–73% were obtained under the optimal reaction conditions after 24 h, with the unsaturated fatty acid esters (oleate and linoleate, 80–90%) as the major products. The immobilized lipase kept the relative activity of 80% after reuse for 6 batches in MeTHF-containing system. Besides, anti-oxidative activities of plant oil-based ascorbyl esters and ascorbic acid were comparable, which could remove α,α-diphenyl-β-picrylhydrazyl (DPPH) free radical of >87%.

Enzymatic Synthesis of l-Ascorbyl Fatty Acid Esters Under Ultrasonic Irradiation and Comparison of Their Antioxidant Activity and Stability.

A series of novel l-ascorbyl fatty acid esters were synthesized by catalization of Novozym(®) 435 under ultrasonic irradiation and characterized by infrared spectroscopy, electrospray ionization mass spectra, and nuclear magnetic resonance. Their properties especially antioxidant activity and stability were investigated. The results showed that the reducing power, the scavenging activity of hydroxyl radical and 2,2-diphenyl-1-picrylhydrazyl radical were decreased with the increase of the number of carbon atoms in fatty acid. The hydroxyl radical scavenging activity and reducing power of l-ascorbyl saturated fatty acid esters were better than that of tert-butylhydroquinone. The induction period in lipid oxidation of l-ascorbyl saturated fatty acid esters and tert-butylhydroquinone were longer than that of l-ascorbyl unsaturated fatty acid esters and l-ascorbic acid both in soybean oil and lard. Besides, the l-ascorbyl fatty acid esters showed different stabilities in different conditions by comparing with l-ascorbic acid, and the l-ascorbyl saturated fatty acid esters were more stable than l-ascorbyl unsaturated fatty acid esters in ethanol solution.

The novel esters farnesyl oleate and farnesyl linoleate are prominent in the surface wax of greasy apple fruit

ABSTRACTThin-layer chromatography was used to screen neutral and acidic fractions of surface waxes from cv. Royal Gala (Malus × domestica Borkh.) apple fruit from known stages of maturity and after postharvest storage with measured variation in skin greasiness. Changes in the amounts and presence of several compounds were observed, with the dominant change occurring in the neutral fraction. A smeary spot on our chromatograms of greasy fruit was analysed by further chromatography and mass spectrometry and found to contain large amounts of novel long-chain unsaturated fatty acid esters of farnesol. Greasy fruit contained 66 µg/cm2 peel of oleyl, linoleyl and linolenyl farnesol esters. These compounds, absent from early-harvest non-greasy apples, are liquid at sub-zero temperatures and appear to be the major contributing component to apple skin greasiness. An observed increase in farnesene, itself a liquid at ambient temperatures, in the peel of greasy apples is also likely to contribute to apple skin greasiness.

Unsaturated fatty acid esters metathesis catalyzed by silica supported WMe5

Metathesis of unsaturated fatty acid esters (FAEs) by silica supported multifunctional W-based catalyst is disclosed. This transformation represents a novel route towards unsaturated di-esters. Especially, the self-metathesis of ethyl undecylenate results almost exclusively on the homo-coupling product whereas with such catalyst, 1-decene gives ISOMET (olefinisomerization and metathesis) products. The olefin metathesis in the presence of esters is very selective without any secondary cross-metathesis products demonstrating that a high selective olefin metathesis could operate at 150°C. Additionally, a cross-metathesis of unsaturated FAEs and α-olefins allowed the synthesis of the corresponding ester with longer hydrocarbon skeleton without isomerisation.