Unsaturated Fatty Acid Esters Research Articles

Revisiting the Potential of Group VI Inorganic Precatalysts for the Ethenolysis of Fatty Acids through a Mechanochemical Approach.

The utilization of biobased feedstocks to prepare useful compounds is a pivotal trend in current chemical research. Among a varied portfolio of naturally available starting materials, fatty acids are abundant, versatile substrates with multiple applications. In this context, the ethenolysis of unsaturated fatty acid esters such as methyl oleate is an atom-economical way to prepare functional C10 olefins with a biobased footprint. Despite the existence of a variety of metathesis catalysts for the latter process, there is a lack of readily available, efficient, and inexpensive catalytic systems based on earth-abundant metals (Mo, W) whose preparation does not require sophisticated syntheses and manipulations. Here, a systematic exploration of homogeneous and heterogeneous inorganic Mo, W (oxy)halides shows that MoOCl4, while inactive as a homogeneous species, forms active and selective silica-supported ethenolysis precatalysts able to reach equilibrium conversion of methyl oleate within a few minutes upon activation with SnMe4. Such heterogeneous MoOCl4-based precatalysts were easily accessed through mechanochemical solvent-free procedures and found to contain, upon characterization by elemental analysis and Raman spectroscopy, isolated (≡SiO)Mo(=O)Cl3 units or polymeric silica-supported [-O(≡SiO)nMoCl4-nO-]m (n = 1, 2) complexes depending on the molybdenum loading. The former isolated species exhibited a higher catalytic performance. The developed heterogeneous precatalysts could be applied to the ethenolysis of various substrates, including polyunsaturated fatty acid esters and industrial fatty acid methyl ester (FAME) mixtures from palm oil transesterification.

The vaporization enthalpies and vapor pressures of Vescepa® and related unsaturated marine FAME by correlation gas chromatography

This article combines data from two previous reports together with new data dealing with the vaporization enthalpies and vapor pressures of a series of saturated and unsaturated fatty acid methyl ester(s) (FAME) by correlation gas chromatography. The work updates earlier results using newly proposed vaporization enthalpies for the saturated FAME used as standards in previous work. This update also provides some insight into the requirements necessary for appropriate column and standard selection for experiments using correlation gas chromatography. Vaporization enthalpies and vapor pressures for saturated FAME methyl heneicosanoate, methyl docosanoate, and methyl tetracosanoate are re-evaluated and together with proposed literature values for methyl tetradecanoate to methyl eicosanoate, are used to evaluate similar properties for a series of unsaturated fatty acid esters. Updated results on the vaporization enthalpies and vapor pressures of a number of unsaturated fatty acid methyl esters (FAME) found in marine oil are reported including several relatively reactive omega-3-polyunsaturated esters. Omega-3-FAME include methyl (9,12,15)Z-octadecatrienoate, methyl (5,8,11,14,17)Z-eicosapentaenoate, and methyl (4,7,10,13,16,19)Z-docosahexenoate among other unsaturated methyl esters. Also included in the study of the omega-3-unsaturated esters is the drug Vescepa®, ethyl (5,8,11,14,17)Z-eicosapentaenoate, a drug used to lower triglyceride levels.

Insights into long-term environmental oxidation of recycled high-viscosity modified asphalt toward durable and sustainable pavement infrastructure

The investigation of long-term environmental oxidation resistance of rejuvenated high-viscosity modified asphalt (HVMA) is of great significance as it unlocks its full potential for recycled utilization, offering improved solutions for sustainable and cost-effective pavement infrastructure. This study aims to comprehensively investigate the long-term environmental oxidation resistance and mechanisms of various oil-based and polymer-based rejuvenated HVMAs. Firstly, the long-term oxidation process of oil-based and polymer-based rejuvenated HVMAs was simulated using the indoor accelerated environmental aging test. Subsequently, a series of rheological tests and X-ray photoelectron spectroscopy (XPS) test were employed to examine the environmental oxidation characterization of rejuvenated HVMAs. Finally, a radar chart was proposed to rank the anti-oxidation capabilities of various rejuvenated HVMAs, accompanied by a detailed oxidation mechanism analysis. The results indicate that polymer-based rejuvenated HVMA exhibits superior environmental oxidation resistance compared to oil-based rejuvenated HVMA. The addition of polymer-based rejuvenators effectively retards the phase angle plateau disappearance and rheological performance deterioration of rejuvenated HVMA during environmental aging. Polymer-based rejuvenators significantly slow down the oxidation rates of carbon and sulfur elements in rejuvenated HVMA. Although the addition of oil-based rejuvenators may not enhance the anti-oxidation capability, the restructuring of the polymer phase structure plays a crucial role in improving the anti-oxidation performance. The ranking of anti-oxidation capabilities among the four polymer-based rejuvenated HVMAs is as follows: SBS-based waste furfural oil (SFO) > SBS-based waste rubber oil (SRO) > SBS-based aromatic oil (SR) > SBS-based waste cooking oil (SWCO). SFO demonstrates the highest resistance to environmental oxidation, primarily attributed to the inherent UV absorption and free radical scavenging capability of furfural oil (FO). SRO exhibits favorable anti-aging performance due to the chemical composition resembling asphalt, which provides enhanced chemical stability. Conversely, waste cooking oil (WCO) contains a significant amount of unsaturated fatty acid esters, which is susceptible to oxidation due to oxygen attack, resulting in the lowest anti-aging capability of SWCO.

Epoxidation of unsaturated fatty acid ester promoted by imidazolium acidic ionic liquids: An unexpected selectivity phenomena

AbstractEpoxidation of linseed oil fatty acid ethyl esters promoted by a series of functionalized imidazolium ionic liquids was studied. In this reaction acidic imidazolium ILs behave not only as an acid catalysts but also play an additional role as a specific activator for the reaction of epoxidation of unsaturated fatty derivatives in H2O2/formic acid oxidation system. The obtained results indicate that the hydrogen‐bonding interaction of imidazolium cation with epoxide group influences the selectivity of the epoxidation reaction. In particular, the presence of unprotected weak “acid” C2‐H proton significantly lowers the selectivity to hydroxyl derivatives. The obtained results also point to another example of specific polyfunctionality of ILs, especially imidazolium one, used as surfactants and process activators.

Modeling and Optimization of Biodiesel Production from Croton macrostachyus Leaves Oil.

The biodiesel produced from Croton macrostachyus (CM) leaves mostly contains unsaturated fatty acid esters with low stability of oxidation. A Croton macrostachyus (CM) leaf, a non-edible resource, was utilized to produce biodiesel. This novel work focuses on the trans-esterification of species known as CM leaves oil to produce biodiesel with the help of CaO nanoparticle (CaO NPs)-catalyzed technique. The esterification process is optimized utilizing response surface methodology (RSM) based on central composite design (CCD). Four parameters that affect the production of biodiesel from Croton macrostachyus (CM) leaves oil have been examined. The optimum operating conditions for the selected four factors have been investigated as reaction time 25.95min, temperature 63.325°C, methanol to oil ratio 28.093:1 in mg/L, and catalyst concentration 3.001%wt with a desirability value of 1. Under the predicted parameters, to optimize the production of biodiesel, the quadratic mathematical models were developed. The optimized trans-esterification result showed that a 96.375% yield of biodiesel (FAME) was found. Three different experimental runs were carried out to validate the proposed model by using the optimized process parameters, and 95.818% (average) of experimental yield have been found. The CM leaves oil biodiesel physicochemical properties were obtained, and it was observed all the tasted properties agree with fuel specifications set by ASTM D6751 standards. In conclusion, this work formulates the baseline and the need for future exploration of CM leaves oil for biodiesel production through different methods.

Size Selectivity in the Hydroxylation of Esters of Unsaturated Fatty Acids

AbstractThe one‐pot two‐steps hydroxylation of fatty acid esters with H2O2 and acetic acid catalyzed by acidic ion exchange resins is reinvestigated aiming to shed light on the relationship between the structure of different substrates and the efficiency of different resins in promoting the hydrolysis of the intermediate epoxides to the corresponding diols. 1H‐NMR analysis of crude reaction mixtures highlight a correlation between the drying process of the resins, their cross‐linking degree, and their effectiveness in promoting such a hydrolysis. Employing dry Dowex 50WX2 as a catalyst, a close relationship is found between the steric hindrance of the substrates and the recovered diol/epoxide ratio, with less hindered substrates preferentially leading to the formation of high diol/epoxide ratios. Accordingly, this procedure is successfully applied to the valorization of the methyl ester of a waste cooking oil. Conversions and selectivity kinetics increase significantly when the amount of the catalyst is increased leading to successfully apply this one‐pot two‐steps hydroxylation reaction to esters of unsaturated fatty acids sterically bulkier than methyl oleate. Spectroscopic and morphological characterization of Dowex 50WX2 shows that the drying process and the interaction with the reagents affect the morphology of the catalyst and promotes the hydrolysis of the intermediate epoxides.Practical applications: Hydroxylated fatty acids are valuable intermediates in the synthesis of a variety of useful biochemicals, including mono‐ and di‐carboxylic acids, biolubricants, and cosmetics. Their work describes the successful application to a variety of esters of unsaturated fatty acids and to the methyl esters of a vegetable oil and a waste cooking oil, of a straightforward hydroxylation procedure, catalysed by commercially available acidic ion exchange resins and occurring under mild and easy to set‐up conditions. The evidence reported on the different catalytic activities and on the structural characterization of the as‐received and dried acidic ion exchange resins are of practical importance in their employment as acidic catalysts.

Evaluation of quercetin omega-6 and -9 esters on activity and structure of mushroom tyrosinase: Spectroscopic and molecular docking studies.

Quercetin is one of the most ubiquitous dietary flavonoids widely distributed in plants and foods of plant origin, and is a potent tyrosinase inhibitor. Quercetin fatty esters could lead to an improve in quercetin lipophilicity which could positively affect its pharmacological activity. In this study, the inhibitory effect of two novel esters of quercetin-linoleic acid (ligand A) and quercetin-oleic acid (ligand B) has been investigated on structure and diphenolase activity of mushroom tyrosinase (MT) by experimental and molecular docking techniques. The inhibitory kinetics study using UV-visible spectrophotometry in the presence of its substrate 3,4-dihydroxyphenylalanine (L-dopa), revealed that both esters successfully inhibit the activity of tyrosinase and reduce the formation of dopaquinone. Results showed that the binding of ligands to MT induced rearrangement and conformational changes of the enzyme. Thermodynamic parameters of these interactions (Ka , ∆G°, ∆H° and ∆S°) were obtained at pH=6.8 and temperatures of 298 and 310K. Molecular docking studies further was applied to calculation of binding energies (ΔGbA =-21.84kJ/mol, ΔGbB =-20.92kJ/mol), inhibition constant values (KIA =160µM, KIB =220µM) and the special binding site. It can be deduced that ligands act as a potential tyrosinase inhibitor and it was found that the best possible interaction condition with binding modes visualize was achieved by ligand A and exhibited the potent tyrosinase inhibitory activity. These findings may be helpful to understand the inhibition mechanism of quercetin fatty acids esters on tyrosinase and provide a convenient screening method to differentiate phenolic tyrosinase inhibitors. PRACTICAL APPLICATIONS: Bioavailability and antioxidant activity of conjugated fatty acids with their bioequivalence in several biological effects and metabolic processes such as beta-oxidation from various forms has been reported to be highly variable and useful. Quercetin shows beneficial role in human health, but its biological effects in vivo is limited by poor bioavailability, low skin permeability and solubility. This study design new tyrosinase inhibitors which helpful to functional research of unsaturated fatty acid esters in the treatment of inflammatory diseases and hyperpigmentation disorders. In addition, undesirable enzymatic browning of plant derived-foods by tyrosinase causes a decrease in market value and economic loss of food products. The results suggest that the conjugation of quercetin with linoleic and oleic acids resulted in novel stronger tyrosinase inhibitors which may have therapeutic applications and replacement of toxic tyrosinase inhibitors and contribute as anti- browning agents in food, cosmetic and pharmaceutical industry.

Thermal degrade analysis of solid insulating materials immersed in natural ester oil and mineral oil by DGA

Globally, natural ester based insulating oils are playing a significant role for insulation design of the transformer. Because of, ester based insulating oil’s critical properties are meeting the standard requirement as liquid dielectrics for transformer. For past century, mineral oil is used as an insulating liquid as well as heat transfer agent for transformer. However, it has less biodegradable characteristics, so which causes negative environmental effects on atmosphere. In addition, availability of fossil fuel is very low. Therefore, the manuscript proposes natural ester oil is alternate liquid dielectrics for transformer. However, critical properties of vegetable oil based liquid dielectrics are depends on the fatty acids. Therefore, two types of oil samples are used such as high saturated fatty acid ester oil (SFEO) and unsaturated fatty acid ester (UFEO), respectively. Initially, oil samples critical properties are measured according to the standard. Subsequently, accelerated thermal aging study has been carried out on all the oil samples for evaluating thermal stability of oil samples. Then, combustible gas estimation of oil samples has been carried out by Dissolved Gas Analyzer. Results are shows that, critical properties of SFEO is comparable that of others. In addition, degradation rate of insulating material is low when it immersed in SFEO that of other oil samples. Finally, SFEO is emitting low combustive gas that of mineral oil with catalyst.

General models for prediction densities and viscosities of saturated and unsaturated fatty acid esters

Biodiesel is a very promising renewable energy, whose properties are determined by fatty acid esters in it. The work aims to develop prediction models based on their molecular structure to estimate the density and viscosity of saturated and unsaturated fatty acid esters in a wide range of temperature and pressure. Densities and viscosities of ethyl hexanoate and ethyl nonanoate were measured from 313.15 K to 363.15 K and at pressures up to 15 MPa to get more experimental data. The effect of temperature, pressure and molecular structure on density and viscosity based on the experimental data in this work and collected from literature found an interesting phenomenon that densities decrease with the increasing carbon atoms number in the chain of the saturated fatty acid esters at low temperature, but there is an opposite trend at high temperature. Two models derived from the Tait equation were proposed for densities with the average absolute relative deviation of 0.15% for saturated fatty acid methyl esters (FAMEs), 0.13% for saturates fatty acid ethyl esters (FAEEs), 0.17% for unsaturated FAMEs, 0.06% for unsaturated FAEEs, respectively. For viscosity, two models based on the Andrade-Tait model were proposed with the average absolute relative deviation of 1.49% for saturated FAMEs, 0.92% for saturated FAEEs, 4.54% for unsaturated FAMEs and 2.15% for unsaturated FAEEs, respectively.

Hitherto Unexplored Three-Membered Heterocyclic Rings Favorably Alter Tribological Properties of Fatty Acid Linear Esters

Esters of linear long-chain unsaturated fatty acids with a variety of alcohols, both linear and branched, are extensively used in the lubricant industry. Extending the generally accepted principle that disruptions to linearity may favorably enhance tribological properties, this article presents a combined experimental and molecular dynamic simulation study to explore the influence of polar ring strain-inducing heterocyclic moieties on the lubrication behavior of such long-chain unsaturated fatty acid esters. The introduction of these disruptive structural features has been achieved by synthesizing the smallest possible three-membered heterocyclic rings (epoxy and thiirane) containing oxygen and sulfur, respectively, in the backbone of oleic acid esters, creating hitherto unexplored derivatives of such esters. The epoxy ester (EE) and thiirane ester (TE) show significant reduction in friction (40%) and wear (30%) with respect to the linear ester (LE), including in elliptical contact experiments at different interfacial contact stresses. Molecular dynamic simulation studies offer valuable insights into the orientation, adsorption, and diffusion behavior of such atomic changes on the lubricant’s physicochemical and tribological characteristics.

Environmental Impact and Aging Properties of Natural and Synthetic Transformer Oils under Electrical Stress Conditions

AbstractAgainst the background of environmental compatibility and unrestricted technical usability, synthetic, and natural transformer oils are critically compared in long‐term tests under high voltage using electrical and instrumental analytical methods. Synthetic alkyl esters of pentaerythrol appear to be sustainable and sometimes superior substitutes for mineral oils in terms of chemical stability, viscosity, permittivity, and heat transport. Natural esters of unsaturated fatty acids are found to be unsuitable for equipment exposed to moist air. Adsorbed water appears to be a general problem in transformer oils. The aging mechanisms and molecular changes during long‐term operation include radical reactions, and the formation, isomerization and cleavage of CC bonds. Extensive material data are provided.

The effect of extractive lacto-fermentation on the bioactivity and natural products content of Pittosporum angustifolium (gumbi gumbi) extracts

Pittosporum angustifolium, known as gumbi gumbi, is a native Australian plant, which has traditionally been used as an Aboriginal medicine. This study investigates the effect of different solvents and extractive fermentation on the content and natural products composition of Pittosporum angustifolium extracts, and compares their antioxidant activity, in vitro α-amylase inhibition, and anti-inflammatory properties. Anti-inflammatory activity of the extracts was determined by measuring the inhibition of nitric oxide (NO) production. Extracts were characterised with FTIR-ATR spectroscopy, and screened for antioxidant activities and α-amylase inhibitory activity via High-performance thin-layer chromatography (HPTLC)-Effect-directed analysis (EDA) with direct bioautography. HPTLC combined with chemical derivatization and bioassays was used for EDA screening. The results show that lactic acid fermentation of gumbi gumbi leaves boosts the antioxidant activity in extracts by increasing the total phenolic content, but does not affect (increase or decrease) α-amylase inhibitory activity or nitrogen scavenging/anti-inflammatory activity. Analysis of the ATR-FTIR spectra from the band at RF = 0.85 that inhibits α-amylase, suggests that fatty acid esters are responsible for the enzyme inhibition; both saturated fatty acid esters in unfermented extracts and unsaturated fatty acid esters in fermented extracts. The ATR-FTIR spectra of the polyphenolics in fermented extracts (RF = 0.15-0.20) suggests the presence of soluble lignin fragments (i.e. lignins depolymerized into monomers and oligomers during the fermentation process).

Synthesis of Bio-Based Aliphatic Polyesters from Plant Oils by Efficient Molecular Catalysis: A Selected Survey from Recent Reports

Recent development in efficient synthesis of (unsaturated) 1,ω-fatty acid diesters (and the diols), which can be used as monomers for synthesis of long chain aliphatic polyesters, especially by Pd-catalyzed isomerization alkoxycarbonylation, Ru-catalyzed olefin metathesis (self-metathesis and cross metathesis), and the tandem olefin metathesis and the ester hydrogenation from plant oils (unsaturated fatty acid esters such as methyl oleate, methyl linoleate, etc.) have been summarized. Recent development for synthesis of (semicrystalline) long chain aliphatic polyesters by polycondensation of 1,ω-dicarboxylic acids and the diols, dehydrogenation polycondensation of the diols or carbonylation polycondensation of the ω-alken-1-ol, and acyclic diene metathesis (ADMET) polymerization of nonconjugated 1,ω-diene (and the tandem ADMET polymerization and hydrogenation system for synthesis of saturated polyester) have also been reviewed. Depolymerization of these long chain aliphatic polyesters was also demonstrated (by olefin metathesis, treatment with alcohols, etc.). Catalyst development for these reactions (more active, under mild conditions) plays a key role in efficient synthesis.

Physicochemical Characterization of Ethoxylation Products of Fatty Acid Esters

The processes of direct ethoxylation of methyl and ethyl esters of unsaturated fatty acids have been described. Two different types of catalysts were employed in those tests: calcium-based catalyst and aluminum-magnesium-based catalyst. Compositions of the synthesized oxyethylates were analyzed with the use of the GC/FID, GC/MS, GPC, and HPLC, HPLC/MS, MALDI methods. Comparative evaluation of the obtained products for both types of catalysts was run in terms of reaction by-products. Biodegradation tests of the oxyethylated products were carried out according to OECD guidelines and physical and chemical properties of oxyethylates were specified which affects the directions of their applications.

Terminal Trialkylsilyl Substituent Effect of Janus-type Molecular Tubes on the Inclusion of Unsaturated Fatty Acid Esters.

A new Janus-type cyclodextrin (CD) molecular tube bearing seven triisopropylsilyl (TIPS) groups at one end is synthesized from a heptakis(6-O-triisopropylsilyl)-β-cyclodextrin (TIPS-β-CD) dimer possessing multiple linkers through the selective removal of seven TIPS groups at the other end. This Janus-type CD tube exhibits a selective inclusion ability for a cis-fatty acid ester over the corresponding trans-fatty acid ester. In addition, the CD tube shows a twofold higher inclusion ability for unsaturated fatty acid esters than the corresponding CD tube bearing seven tert-butyldimethylsilyl (TBDMS) groups, indicating that the molecular size of the terminal substituents remarkably affects the inclusion ability of the CD tube.

Chemical constituents of Eremomastax speciosa (Hochst.) Cufod leaves and its cytotoxic potential on NIH-3T3 cells

This study aimed at assessing the cytotoxicity of Eremomastax speciosa crude extract on NIH-3T3 fibroblast cell lines and reporting the chemical constituents in the extract. The MTT assay on NIH-3T3 cells showed a significantly lower (p < 0.05) inhibition from E. speciosa (IC50 > 30 µg/mL) compared to cyclohexamide (IC50 > 0.8 µg/mL). This result validates the non-toxicity observed with the use of E. speciosa on normal cells at low to moderate doses. Four compounds were isolated and identified from their EIMS as well as 1D and 2D NMR spectroscopic data namely hydroxyandrographolide (1), stigmasterol glucoside (2), (Z)-4-coumaric acid 4-O-β-D-apiofuranosyl-(1’’→2’)-O-β-D-glucopyranoside (3) and 5-methoxy-4,4′-di-O-methyl- secolariciresinol-9′-monoacetate (4). These compounds are isolated from this species for the first time. Thirteen volatile constituents were detected in the extract using gas chromatography mass spectrometry (GC-MS). Besides 6,10,14-trimethy-2-pentadecanone (12.63%), mostly fatty acid esters were detected in high amounts notably ethyl hexadecanoate (16.00%), ethyl-9,12,15-octadecatrienoate (11.51%) and 9,12-octadecadienoic acid ethyl ester (8.05%). This study revealed many unsaturated fatty acid esters in E. speciosa and is noteworthy that ω-3 and ω-6 fatty acid esters were predominant, hence an added nutritional value to this plant.
 
 KEY WORDS: Eremomastax speciosa, Secondary metabolites, NIH-3T3 cytotoxicity, NMR, GC-MS
 
 Bull. Chem. Soc. Ethiop. 2020, 34(3), 633-640.
 DOI: https://dx.doi.org/10.4314/bcse.v34i3.18

Solvent-free synthesis of phytosterol linoleic acid esters at low temperature.

Phytosterol unsaturated fatty acid esters show much higher oil solubility than free phytosterol. Thus, development of a green and low-cost method for the preparation of phytosterol fatty acid esters is highly desirable in the food industry. Herein, we have developed a simple chemical method toward efficient preparation of phytosterol linoleic acid esters at very mild temperature (60 °C) using 4-dodecylbenzenesulfonic acid (DBSA) as the catalyst. In this work, low-temperature esterification of phytosterols (soybean sterol) with linoleic acid could produce the corresponding phytosterol esters above 95% conversion under solvent-free conditions. In addition, this simple method could be applied to produce phytosterol esters through esterification of phytosterol with an unsaturated fatty acid mixture resulting from the hydrolysis of various vegetable oils. Importantly, no extra organic solvents and no extra water-removal operations or equipment were required in this chemical esterification method. The mechanism investigation suggested that the DBSA-catalyzed low-temperature esterification would form micro-emulsions of water-in-oil (W/O), which could achieve automatic separation of water from the hydrophobic system to avoid reverse reaction hydrolysis and rapidly promote the equilibrium reaction towards phytosterol esters.

A Mini Review on the Cold Flow Properties of Biodiesel and its Blends

Biodiesels are renewable fuel that may be produced from various feedstock using different techniques. It is endorsed in some countries of the world as a viable substitute to diesel fuel. While biodiesel possesses numerous benefits, the cold flow properties (CFP) of biodiesel in comparison with petro-diesel are significantly less satisfactory. This is due to the presence of saturated and unsaturated fatty acid esters. The poor CFP of biodiesel subsequently affects performance in cold weather and damages the engine fuel system, as well as chokes the fuel filter, fuel inlet lines, and injector nozzle. Previously, attempts were made to minimize the damaging impact of bad cold flow through the reduction of pour point, cloud point, and the cold filter plugging point of biodiesel. This study is focused on the biodiesel CFP-related mechanisms and highlights the factors that initialize and pace the crystallization process. This review indicates that the CFP of biodiesel fuel can be improved by utilizing different techniques. Winterisation of some biodiesel has been shown to improve CFP significantly. Additives such as polymethyl acrylate improved CFP by 3-9 ° C. However, it is recommended that improvement methods in terms of fuel properties and efficiency should be carefully studied and tested before being implemented in industrial applications as this might impact biodiesel yield, cetane number, etc.

New unsaturated fatty acids from the aerial parts of Lycopodiastrum casuarinoides

Abstract Two new unsaturated fatty acid esters (1 and 2) and five new unsaturated fatty acids (4–8), together with two known analogs (3 and 9) were isolated from the aerial parts of Lycopodiastrum casuarinoides. Their structures were unambiguously elucidated by obtaining extensive spectroscopic data and comparing them with data in the literature. The absolute configurations of 1 and 2 were established by a modified Mosher's method. All compounds were evaluated in vitro for their inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Compound 8 exhibited the most potent inhibitory activity against AChE with an IC50 value of 1.16 ± 0.13 μM.

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.