Free Methanol Research Articles

A CO2-emission free direct methanol fuel cell for simultaneous production of electrical energy and value-added chemicals

It remains challenges to efficiently convert carbon-based fuels such as methanol from CO2 into electrical energy while without CO2 greenhouse gas emission. Herein, a CO2-emission free direct methanol fuel cell (DMFC) has been realized through using unique Pt-CoOOH/nickel foam anode with high electro-catalytical selectivity, activity and stability. The DMFCs demonstrate simultaneous production of 18 mol of formate for every 1 kWh of electricity output with peak power density of 49.3 mW cm−2 and high selectivity of formate value-added chemicals up to 96 %. Moreover, this simple procedure does not consume energy while output electricity compared to the traditional formate production. It either does not use the toxic feedstock of CO and the reaction conditions are very mild. The in-situ Raman test indicates that CoOOH acts as an auxiliary active site to promote the conversion of *HCO to *HCOOH and improve the selectivity of formate. In-situ IR tests and density functional theory (DFT) calculations confirm that methanol tends to be oxidized selectively into formate rather than complete-oxidizing into CO2. This study achieves clean and efficient utilization of carbon-based fuels to co-generate electrical energy and value-added chemicals while no CO2 greenhouse emission, even realize the “negative carbon” cycle.

Antibiosis and GC-MS of secondary metabolites of rhizosphere bacteria from Manatee foodplants in the humic freshwater ecosystem of Eniong river, Nigeria

Microorganisms are able to synthesize secondary metabolites of various structures and bioactivities. These metabolites are produced to help the organism compete successfully with other organisms in their natural habitat and adapt with changing environmental milieu. The ability of rhizosphere bacteria (Bacillus subtilis NC_000964.3 and Pseu-domonas aeruginosa NC_002516.2) isolated from the rhizospheric soil of Manatee food plants Mimosa pygra, Ipomeoa aquatica and Pistia stratoites to inhibit the growth of human pathogens (P. aeruginosa, E. coli, S. aureus and B. subtilis) was evaluated using standard methods. It was observed that the growth extracts of B. subtilis strains M5, M8 and P7 and P. aeruginosa strains I3 and M9 contained useful bioactive compound. GC-MS analysis of the cell -free methanol extract of the antibiotic producing bacterial strains was also evaluated and the results showed that their inhibitory potentials against bacterial pathogens are due to the presence of phenylethyl alcohol, 2-ethyl-4-methyl-1,3-dioxolane, bicyclo [4.2.0] octa-1,3,5-triene and 4-amino-2-methyl-5,6-dimethyl pyrimidine for B. subtilis and 3,4-dimethyl tetrahydrofuran, 4,6-dimethyl-4-hydroxy-5- heptenoic acid and 2,4-dimethyl-4-heptanol for Pseudomonas aeruginosa. These strains of rhizosphere bacteria may be exploited to produce new antibiotics.

Reduction of CO to Methanol with Recyclable Organic Hydrides.

The reaction steps for the selective conversion of a transition metal carbonyl complex to a hydroxymethyl complex that releases methanol upon irradiation with visible light have been successfully quantified in acetonitrile solution with dihydrobenzimidazole organic hydride reductants. Dihydrobenzimidazole reductants have been shown to be inactive toward H2 generation in the presence of a wide range of proton sources and have been regenerated electrochemically or photochemically. Specifically, the reaction of cis-[Ru(bpy)2(CO)2]2+ (bpy = 2,2'-bipyridine) with one equivalent of a dihydrobenzimidazole quantitatively yields a formyl complex, cis-[Ru(bpy)2(CO)(CHO)]+, and the corresponding benzimidazolium on a seconds time scale. Kinetic experiments revealed a first-order dependence on the benzimidazole hydride concentration and an unusually large kinetic isotope effect, inconsistent with direct hydride transfer and more likely to occur by an electron transfer-proton-coupled electron transfer (EΤ-PCET) or related mechanism. Further reduction/protonation of cis-[Ru(bpy)2(CO)(CHO)]+ with two equivalents of the organic hydride yields the hydroxymethyl complex cis-[Ru(bpy)2(CO)(CH2OH)]+. Visible light excitation of cis-[Ru(bpy)2(CO)(CH2OH)]+ in the presence of excess organic hydride was shown to yield free methanol. Identification and quantification of methanol as the sole CO reduction product was confirmed by 1H NMR spectroscopy and gas chromatography. The high selectivity and mild reaction conditions suggest a viable approach for methanol production from CO, and from CO2 through cascade catalysis, with renewable organic hydrides that bear similarities to Nature's NADPH/NADP+.

Methyl oleate for plant protection products formulations: Enzymatic synthesis, reaction kinetics and application testing

This study presents a solvent-free enzymatic approach for the synthesis of fatty acid methyl esters (FAMEs), such as methyl oleate, for their application as adjuvant in plant protection products (PPP) formulations. The direct esterification between free fatty acid and methanol was optimized to achieve 98% acid conversion. The kinetics of this conversion was accurately described by a simple second order mechanism and non-linear regression was applied to calculate the rate constants of the forward and backward reactions based on full progress curves data. The rate constant of the forward reaction (synthesis) was one order of magnitude higher than the backward reaction (hydrolysis) and favored formation of the target methyl ester product, rendering the removal of water unnecessary. Enzymatically synthesized methyl oleate was benchmarked against the chemically synthesized compound, showing matching results in terms of stability, spreadability and emulsifying capacity in plant care formulations. The enzymatic synthesis of FAMEs under solvent free conditions allows to achieve a safer and more sustainable character for carrier solvents in PPP formulations.

Formation and Tandem Mass Spectrometry of Doubly Charged Lipid-Metal Ion Complexes.

Phospholipids are major components of most eukaryotic cell membranes. Changes in metabolic states are often accompanied by phospholipid structure variations. The structural changes of phospholipids are the hallmark of disease states, or specific lipid structures have been associated with distinct organisms. Prime examples are microorganisms that synthesize phospholipids with, for example, different branched chain fatty acids. Assignment and relative quantitation of structural isomers of phospholipids that arise from attachment of different fatty acids to the glycerophospholipid backbone are difficult with routine tandem mass spectrometry or with liquid chromatography without authentic standards. In this work, we report on the observation that all investigated phospholipid classes form doubly charged lipid-metal ion complexes during electrospray ionization (ESI) and show that these complexes can be used to assign lipid classes and fatty acid moieties, distinguish isomers of branched chain fatty acids, and relatively quantify these isomers in positive-ion mode. Use of water free methanol and addition of divalent metal salts (100 mol %) to ESI spray solutions afford highly abundant doubly charged lipid-metal ion complexes (up to 70 times of protonated compounds). Higher-energy collisional dissociation and collision-induced dissociation of doubly charged complexes yield a diverse set of lipid class-dependent fragment ions. In common for all lipid classes is the liberation of fatty acid-metal adducts that yield fragment ions from the fatty acid hydrocarbon chain upon activation. This ability is used to pinpoint sites of branching in saturated fatty acids and is showcased for free fatty acids as well as glycerophospholipids. The analytical utility of doubly charged phospholipid-metal ion complexes is demonstrated by distinguishing fatty acid branching-site isomers in phospholipid mixtures and relatively quantifying the corresponding isomeric compounds.

Removal of Cyanide in Gold Cyanide Residues through Persulfate-Advanced Oxidation Process

The toxic cyanides in gold cyanide residues produced in the cyanidation process of gold extraction threaten environmental safety and inhibit the recovery of valuable metals. In this study, the removal of cyanide through the persulfate-advanced oxidation process was investigated, and heat activation and ultrasonic activation were tested for cyanide removal. The results showed that cyanide in cyanide residue could be removed by 2.0 wt.% potassium persulfate at pH 10.0 after 60 min reaction with a removal efficiency of 53.47%. The removal efficiency increased to 62.18% at T = 60 °C for heat activation and 74.76% with an ultrasonic power of 100% for ultrasonic activation. The cyanide content in the toxic leaching solution of the residue after the ultrasonic-activated persulfate-advanced oxidation process (3.84 mg/L) reached the national standard of China. Two kinds of free radical scavengers, tert-butanol and methanol, were used to investigate the generation of free radicals. The results showed that both SO4•− and HO• were produced and accelerated the oxidation of cyanide, and HO• played a major role under alkaline conditions. According to XPS analysis, the oxidation of ultrasonic-activated persulfate focused on cyanide removal rather than pyrite in cyanide residue. More cyanides were transferred from the cyanide residue to the liquid phase, leading to the high efficiency of ultrasonic activation. The ultrasonic-activated persulfate-advanced oxidation process has potential application prospects for the treatment of gold cyanide residues.

A Theoretical and Experimental Study for Enzymatic Biodiesel Production from Babassu Oil (Orbignya sp.) Using Eversa Lipase

A theoretical and experimental study was carried out on the biocatalytic production of babassu biodiesel through enzymatic hydroesterification. The complete hydrolysis of babassu oil was carried out using a 1:1 mass solution at 40 °C for 4 h using 0.4% of lipase from Thermomyces lanuginosus (TLL). Then, with the use of Eversa® Transform 2.0 lipase in the esterification step, a statistical design was used, varying the temperature (25–55 °C), the molar ratio between free fatty acids (FFAs) and methanol (1:1 to 1:9), the percentage of biocatalyst (0.1% to 0.9%), and the reaction time (1–5 h) using the Taguchi method. The ideal reaction levels obtained after the statistical treatment were 5 h of reaction at 40 °C at a molar ratio of 1:5 (FFAs/methanol) using 0.9% of the biocatalyst. These optimal conditions were validated by chromatographic analysis; following the EN 14103 standard, the sample showed an ester concentration of 95.76%. A theoretical study was carried out to evaluate the stability of Eversa with FFAs. It was observed in the molecular docking results that the ligands interacted directly with the catalytic site. Through molecular dynamics studies, it was verified that there were no significant conformational changes in the studied complexes. Theoretical and experimental results show the feasibility of this process.

Degradation of metronidazole in water using dielectric barrier discharge synergistic with sodium persulfate

A series of water pollution problems caused by antibiotic wastewater need to be solved urgently. Dielectric barrier discharge (DBD) is one of the advanced oxidation processes (AOPs) with the advantages of rapid reaction, stable discharge. Sodium persulfate (PS) is a reagent with strong oxidation and good water solubility, but need to be activated in order to effectively used in wastewater treatment. DBD can activate PS. The effects of technological parameters (input power, air velocity, Metronidazole (MTZ) initial concentration, discharge gap), material of external electrode and sodium persulfate addition amount on the degradation rate and energy efficiency were investigated for MTZ in simulate antibiotic wastewater and a self-made immersed DBD reactor alone or in synergy with PS. Under the optimized conditions of input power of 12 W, air velocity of 150 mL·min−1, MTZ initial concentration of 50 mg·L-1 and discharge gap of 2.0 mm, the maximum degradation rate of MTZ was 60.71 % and 58.68 % for copper wire and nickel–chromium wire as external electrode, respectively. The maximum synergistic degradation rate was 96.48 % and 90.30 % with copper or nickel–chromium external electrode, respectively, when the molar ratio of PS to MTZ was 50. The contributions of O3, ·OH and SO4-· free radicals in the process of DBD synergistic degradation of MTZ with PS were explored via Indigo sodium disulfonate spectrophotometry and free radical scavenger methanol, tert-butyl alcohol. The ozone concentration in the solution can reach 2.965 × 10-2 mmol·L-1. The contributions of ·OH and SO4-· free radicals were 46.73 % and 29.69 %, respectively. The probable degradation paths of MTZ were also proposed based on intermediate product analysis with LC-MS.

In vitro antioxidant, anticholinesterase, tyrosinase activity studies, and LC-MS/MS simultaneous determination of 37 bioactive compounds in Indigofera heterantha

The flowering plant Indigofera heterantha generally known as Indigo of Himalayan, was extracted with n-hexane, ethyl acetate, and methanol by using Soxhlet apparatus. The extracts were studied for their antioxidants and enzyme inhibition activities. Against DPPH free radical-scavenging activity methanol extract was found moderately active (IC 50 : 158.41 ± 1.1.66 µg/mL). The ethyl acetate and n-hexane extracts exhibited the best ABTS radical scavenging activity (IC 50 : 31.32 ± 2.50 and 52.0 ± 0.89 µg/mL respectively). Against the metal chelating activity, n-hexane extract was active IC 50 : 52.36 ± 0.95 µg/mL. The n-hexane and ethyl acetate extracts demonstrated the best β –carotene antioxidant activity (IC 50 : 22.32 ± 0.84 and 60.66 ± 0.35 μg/mL respectively). Against acetylcholinesterase (AChE), ethyl acetate and methanol extracts were moderate active (IC 50 : 133.58 ± 0.870, and 137.97 ± 0.97 µg/mL respectively). The ethyl acetate extract showed Butyrylcholinesterase (BChE) inhibitory activity with IC 50 value of 121.9 ± 1.13 µg/mL. Against tyrosinase activity, ethyl acetate and n-hexane extracts activity with an IC 50 value of 79.25 ± 0.15 and 131.48 ± 0.88 µg/mL respectively. The phenolic contents of the methanolic extract of I. heterantha were also determined by using LC-MS/MS. The major constituents were Quinic acid (57,333.04 μg/g), malic acid (1135.16 μg/g), gallic acid (201.13 μg/g), isoquercitrin (113.63 μg/g), Rutin (92.97 μg/g), and Salicylic acid (40.45 μg/g). Keeping in view the overall biological activities of I. heterantha, it might be used in food industries and pharmaceuticals as a potential functional food ingredient.

Catalytic wet air oxidation of azo dye (reactive red 2) over copper oxide loaded activated carbon catalyst

The degradation of reactive red 2 mono azo dye through catalytic wet air oxidation process using copper oxide loaded activated carbon catalyst showed remarkable a result. The AC was prepared from water hyacinth root using the physic-chemical activation method and the copper oxide loaded activated carbon (CuO/AC) catalyst was prepared through the wet impregnation method. It was characterized by: Fourier transform infrared (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermo gravimetric analysis (TGA) instruments. The influence of operating parameters (catalyst dose (2–6 g/L), reaction temperature (70–120 °C), and oxygen partial pressure (1–3 bar)) on reactive red 2 (RR2) dye decolorization and chemical oxygen demand (COD) conversion at a reaction time of (10–120 min) were investigated. Complete dye decolorization (100%) and 88.57% chemical oxygen demand (COD) conversion were achieved at maximum operating conditions, 6 g/L of catalyst dose, 120 °C reaction temperature, and 3 bar of oxygen partial pressure within 120 min of reaction time. The percentage of dye decolorization was 42.91 and 59% in the presence of free radical scavengers sodium bicarbonate (NaHCO3) and methanol (CH3OH) respectively. Also, the performance of the reused catalyst was decreased. Based on the percentage of germination index of lepidium sativium seed, the phytotoxicity of the treated dye solution has low toxicity (62.67%) than the untreated dye solution (34.80%).

Synthesis, Spectroscopic, Characterization and X-ray Structures of Lanthanide(III) Complexes Derived from 1,5-bis(phenyl(pyridin-2-yl)methylene)carbonohydrazide

The use of 1,5-bis (phenyl (pyridin-2-yl) methylene) carbonohydrazide (H₂L) in the coordination chemistry of lanthanides (III) yielded complexes in which two ligand molecules are present. The synthesis was carried out using a Ln/H₂L ratio of 1/2 to lead mononuclear complexes of [Ln(H₂L)₂(<i>η</i>²-NO₃)_3-x](NO₃)_x (Ln=La (1), Sm (4), Gd (6) and Yb (7)), [Ln(H₂L)₂(NO₃)₃] (Ln=Pr(2), Eu(5) and a co-crystal {[Nd(H₂L)₂(<i>η</i>²-NO₃)₂(<i>η¹</i>-NO₃)], [Nd(H₂L)₂(<i>η²-</i>NO₃)(<i>h¹-</i>NO₃)(H₂O)]}.(NO₃).2CH₃OH} (3). The structures of the complexes (2) and (3)were solved by X-ray crystallography on a single crystal. In the mononuclear complex of Pr<SUP>III</SUP>, two neutral ligand molecules act in tridentate fashion. In the co-crystal complex, one of the Nd<SUP>III</SUP> atom is coordinated by two ligand molecules acting tridentately in neutral form and three nitrate anions acting in bidentate fashion while the second Nd<SUP>III</SUP> atom is coordinated by two ligand molecules acting tridentately in neutral form, one monodentate nitrate anion, one bidentate nitrate anion and one water molecule. The neutrality of the complex is ensured by one free nitrate anion. Two free methanol molecules are present. Complex (2) crystallizes in the triclinic space group P-1 with the following parameters: a=10.128 (2) Å, b=12.2285 (19) Å, c=20.816 (5) Å, α=85.634 (4), β=81.870 (4)°, γ=87.210 (5)°, V=2542.9 (9) ų, Z=2, R₁=0.0640, wR₂=0.1377. Complex (3) crystallizes in the monoclinic space group P2₁/c with the following parameters: a=10.4554 (12) Å, b=44.089 (6) Å, c=23.212 (3) Å, β=90.851 (2)°, V=10699 (2) ų, Z=4, R₁=0.0630, wR₂=0.1690. The coordination sphere of the twelve-coordinated Pr<SUP>III</SUP> atom is best described as distorted icosahedron. In the co-crystal one of the Nd<SUP>III</SUP> atom is eleven-coordinated while the second Nd<SUP>III</SUP> atom is ten-coordinated. The environments around the Nd<SUP>III</SUP> atoms are respectively best described as distorted pentacapped trigonal prism and a distorted bicapped square antiprism, respectively. Supramolecular structures are consolidated by numerous hydrogen bonds.

Antioxidant Property and Oral Glucose Tolerance of Stem Extract of Andrographis paniculata – Nees

This research aims to investigate the antioxidant property and oral glucose tolerance of stem extract of Andrographis paniculata using standard methods. The antioxidant activity of the extracts were assessed using total phenol, total flavonoid, ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), nitric oxide, GSH (gluthatione), super oxide, DPPH [1,1-di-phenyl-2-picryl hydrazyl] and ascorbic acid. The oral glucose tolerance of methanol stem extract of A. paniculata was carried out using wistar albino rats. The Wistar albino rats were divided into six groups consisting of five rats each. Group 1 was given water only, group two to group five were induced with 2g/kg of glucose. After 30 minutes, group 3 and 4 were treated with the doses of 15 mg/kg and 30 mg/kg of the extract while group 5 was treated with glibenclamide respectively. The blood glucose level of each group was monitored for 2hours at 30 minutes interval and compared with the control that was given water only. The result shows that the extracts were able to scavenge free radicals but methanol stem extract of A. paniculata performed better in scavenging free radicals as compared to others. The blood sugar levels of the rats treated with doses of 15 and 30 mg/kg of methanol stem extract of A. paniculata were significantly lower than the group of rats that were fed with only glucose and the group of rats treated with glibenclamide. The glucose-lowering efficiency of the extract was between 60-120 minutes. Findings from this present study revealed that A. paniculata is a potential plant that can scavenge free radicals and also possess hypoglycemic activity.

Sol-Gel Entrapped Lewis Acids as Catalysts for Biodiesel Production.

Replacing fossil fuels with biodiesel enables the emission of greenhouse gases to be decreased and reduces dependence on fossil fuels in countries with poor natural resources. Biodiesel can be produced by an esterification reaction between free fatty acids (FFAs) and methanol or by transesterification of triglycerides from oils. Both reactions require homogeneous or heterogeneous catalysis. Production of biodiesel catalyzed by heterogeneous catalysts seems to be the preferred route, enabling easy product separation. As we have previously shown, the Lewis acids AlCl3 and BF3 can serve as highly efficient catalysts under ultrasonic activation. The present study focused on the development of oleic acid (OA) esterification with methanol by the same catalysts immobilized in silica matrices using the sol–gel synthesis route. During the course of immobilization, AlCl3 converts to AlCl3 × 6H2O (aluminite) and BF3 is hydrolyzed with the production of B2O3. The immobilized catalysts can be reused or involved in a continuous process. The possibility of biodiesel production using immobilized catalysts under ultrasonic activation is shown for the conversion of FFAs into biodiesel in batch and continuous mode.

Solvated State of Ethylenediamine in Nonaqueous Solvents, According to Quantum Chemical Data

Quantum chemical modeling is used to study the equilibrium geometric parameters and atomic charges in molecules of ethylenediamine (En) in the free state, methanol (MeOH), acetonitrile (AN), N,N‑dimethylformamide (DMF) and dimethylsulfoxide (DMSO), along with the Gibbs energies and enthalpies of amine solvation in the considered solvents. It is found that the conformational state of En is approximately the same in each solvent. In aprotic solvents, the solvation of En proceeds mainly because of the universal type of interactions between amine molecules and solvent molecules; in methanol, solvation energy of En and the solvate’s stability are determined by both universal and specific types of solute–solvent interactions with the contribution from the universal type of interactions predominating.

Two-step Biodiesel Production from Used Activated Bleaching Earth at Palm Oil Refining Plant

A study on two-step biodiesel production of agricultural by-products, namely palm oil derived using activated bleaching earth )UABE), collected from the Oleen Palm Oil industrial refining plant consisting of 22.4 % of waste oil. This waste oil showed free fatty acid content and a saponification value of 15.5 % and 199.7 mg KOH/g, respectively. The FFA content after esterification should be approximately 1.0%, not only to save glycerol and the catalyst involved in the esterification but also to achieve high biodiesel conversion during the transesterification. An alkaline catalyst was successfully used to produce biodiesel in the second step. A 97.6% conversion to biodiesel based on the European Standard EN 14214:2003 was achieved under the conditions (1.0% NaOH catalyst relative to waste oil, the molar ratio of free fatty acid, and methanol of 1:13.22, 60ºC, 1h). Overall, this novel two-step process achieved highly enhanced biodiesel conversion (74.6% to 100.0%) with a significantly increased molar ratio of free fatty acid and methanol (1:2.71 to 1:15.89) and catalyst requirements (1.0% NaOH).

Structure, Dynamics, and Accurate Laboratory Rotational Frequencies of the Acrylonitrile-Methanol Complex.

The hydrogen-bonded complex between acrylonitrile (CH2=CHCN) and methanol has been characterized spectroscopically in the millimeter wave range (59.6–74.4 GHz) using a free jet absorption millimeter wave spectrometer. Precise values of the rotational and centrifugal distortion constants were obtained from the measured frequencies of the complex of acrylonitrile with CH3OH and CD3OD. The analysis of the splittings of the rotational lines due to the hindered internal rotation of the methanol methyl group led to the determination of a V3 value of 221.9(7) and 218(5) cm–1 for the complexes of CH3OH and CD3OD, respectively, and these values are about 40% lower than that of free methanol. The structure of the observed conformation is in agreement with the global minimum determined at the MP2/aug-cc-pVTZ level of calculation, and the counterpoise corrected intermolecular binding energy, obtained at the same theoretical level, is De = 26.3 kJ mol–1.

BASF readies CO2-free methanol process

BASF is patenting a process that it says will produce methanol without greenhouse gas emissions. The process begins with making synthesis gas, a mixture of carbon monoxide and hydrogen, via partial oxidation of methane. Flue gases from the methanol synthesis and distillation steps are then treated in a BASF process, dubbed OASE, to recover the carbon dioxide, which BASF says will be returned to the beginning of the process and treated with hydrogen. The company doesn’t expect the process to reach commercial scale for another 10 years.

Methanol Electro-Oxidation in Alkaline Medium by Ni Based Binary and Ternary Catalysts: Effect of Iron (Fe) on the Catalyst Performance

Pt free methanol electro oxidation catalysts with stable response are of interest to reduce the overall cost of the direct methanol fuel cell (DMFC). Here, nickel based bi and tri metallic catalysts have been prepared on multiwall carbon nanotube (MWCNT) support by incipient wetness impregnation method. Methanol oxidation performance was investigated in 1 M KOH by cyclic-voltammetry (CV) and chronoamperometry (CA). The results of electrochemical tests showed that among all the catalysts tested, catalyst sample, CAT-3 exhibited the highest current density of 125.5 mA/cm2 and have stable electrochemical response, which is very promising. These catalysts have been characterized by field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray-(EDX), transmission electron microscopy (TEM), X-ray diffraction XRD and X-ray photoelectron spectroscopy (XPS) to study the structural and morphological properties. Characterization results revealed small and uniform particle size distribution and better homogeneity in CAT-3. It was also observed that addition of ‘Fe’ in tri metallic catalyst lowers the Cu contents in the catalysts and in the contrary lowers the electro-catalytic performance. All the catalyst found to be quite stable and CAT-3 gave the highest oxidative current response, which is attributed to higher Cu contents.

Producing Fatty Acid Methyl Esters from Free Fatty Acids with Ionic Liquids as Catalyst

AbstractThree Brønsted acidic imidazole dicationic ionic liquids (ILs) with different length of alkyl chains, [Cn(Mim)2][HSO4]2 (n = 3, 6, 12), were prepared and used as catalyst for the esterification reaction of free fatty acids and methanol. Taking oleic acid as model acid, the catalytic performances of the synthesized ILs for the esterification were evaluated. The main physicochemical properties of the ILs, thermal stability, acidity, solubility in common solvents, and causticity on Austenitic stainless steel 316, were examined. [C3(Mim)2][HSO4]2 demonstrated the highest catalytic activity and enabled to assess the preliminary optimum esterification condition of oleic acid and methanol. Under optimized reaction conditions, the yield of oleic acid methyl ester was up to 95 %. The ILs have great potential as catalysts for producing fatty acid methyl esters from long‐chain free fatty acids.

SOLVATION CONTRIBUTIONS OF PYRIDINE FUNCTIONAL GROUPS IN TRANSFER ENTHALPY OF AMINE FROM METHANOL TO ACETONITRILE, DIMETHYL SULFOXIDE AND DIMETHYLFORMAMIDE

Quantum-chemical calculations of the energy and structure of pyridine molecule (Py) in the free state, methanol (MeOH), acetonitrile (AN), dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) have been performed using the density functional theory (DFT) at the B3LYP with the 6-31G basic set supplemented by polarization and diffuse functions and within the model of the self-consistent reactive field (PCM). It was found that the transfer of the pyridine molecule from the free state to the MeOH, AN, DMF and DMSO media leads to: an increase in bond distances only between nitrogen and carbon atoms of amine; significant changes in the charges on the carbon atoms associated with the reaction center (the growth of positive charges varies in the series: DMF = DMSO &lt; MeOH = AN); an increase in the positive charge on hydrogen atoms, which varies in the series: MeOH = AN &lt; DMF = DMSO. A comparative analysis of the results from quantum chemical calculations was carried out with data on transfer enthalpies of amine from MeOH to AN, DMF and DMSO (ΔtrH°(Py)MeOH → solv) which were obtained by calorimetric method. It was found that the resolvation of the nitrogen atom gives the major contribution to the change in the solvate state of pyridine when the composition of the solvent MeOH → DMF and MeOH → AN changes. In case of transfer of Py from MeOH to DMSO, contributions from the resolvation of the nitrogen atom and the hydrocarbon radical to the overall energy of the resolvation of molecule are approximately the same.Forcitation:Kuz’mina I.A., Volkova M.A., Kuz’mina K.I., Belova N.V., Sharnin V.A. Solvation contributions of pyridine functional groups in transfer enthalpy of amine from methanol to acetonitrile, dimethyl sulfoxide and dimethylformamide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 4-9