Showing papers on "Transesterification published in 2003"

Impact of Ionic Liquid Physical Properties on Lipase Activity and Stability

Abstract: Lipase activity and stability was investigated in dialkylimidazolium and pyrrolidinium-based ionic liquids with a variety of anions including hexafluorophosphate, acetate, nitrate, methanesulfonate, trifluoroacetate, and trifluoromethylsulfonate. The initial rate of lipase-catalyzed transesterification of methyl methacrylate in these ionic liquids and several organic solvents was examined as well as the polytransesterification of divinyl adipate and 1,4-butanediol. Free lipase (Candida rugosa) catalyzed the transesterification of methyl methacrylate in 1-butyl-3-methylimidazolium hexafluorophosphate at a rate 1.5 times greater than in hexane. However, no detectable activity was observed in all the “hydrophilic” ionic liquids studied. Methods of enzyme stabilization including adsorption, PEG-modification, and immobilization in polyurethane foam were ineffective in improving enzymatic activity in the hydrophilic ionic liquids. Polytransesterifications performed in 1-butyl-3-methylimidazolium hexafluorophosp...

An experimental comparison of methods to use methanol and Jatropha oil in a compression ignition engine

Abstract: In this work various methods of using vegetable oil (Jatropha oil) and methanol such as blending, transesterification and dual fuel operation were studied experimentally. A single cylinder direct injection diesel engine was used for this work. Tests were done at constant speed of 1500 rev min −1 at varying power outputs. In dual fuel operation the methanol to Jatropha oil ratio was maintained at 3:7 on the volume basis. This is close to the fraction of methanol used to prepare the ester with Jatropha oil. Brake thermal efficiency was better in the dual fuel operation and with the methyl ester of Jatropha oil as compared to the blend. It increased form 27.4% with neat Jatropha oil to a maximum of 29% with the methyl ester and 28.7% in the dual fuel operation. Smoke was reduced with all methods compared to neat vegetable oil operation. The values of smoke emission are 4.4 Bosch Smoke Units (BSU) with neat Jatropha oil, 4.1 BSU with the blend, 4 BSU with methyl ester of Jatropha oil and 3.5 BSU in the dual fuel operation. The Nitric Oxide (NO) level was lower with Jatropha oil compared to diesel. It was further reduced in dual fuel operation and the blend with methanol. Dual fuel operation showed higher hydrocarbon (HC) and carbon monoxide (CO) emissions than the ester and the blend. Ignition delay was higher with neat Jatropha oil. It increased further with the blend and in dual fuel operation. It was reduced with the ester. Peak pressure and rate of pressure rise were higher with all the methods compared to neat Jatropha oil operation. Jatropha oil and methyl ester showed higher diffusion combustion compared to standard diesel operation. However, dual fuel operation resulted in higher premixed combustion. On the whole it is concluded that transesterification of vegetable oils and methanol induction can significantly enhance the performance of a vegetable oil fuelled diesel engine.

Efficient Transesterification/Acylation Reactions Mediated by N-Heterocyclic Carbene Catalysts

Abstract: Imidazol-2-ylidenes, a family of N-heterocyclic carbenes (NHC), are efficient catalysts in the transesterification involving numerous esters and alcohols. Low catalyst loadings of aryl- or alkyl-substituted NHC catalysts mediate the acylation of alcohols with enol acetates in short reaction times at room temperature. Commercially available and more difficult to cleave methyl esters react with primary alcohols in the presence of alkyl-substituted NHC to efficiently form the corresponding esters. While primary alcohols are selectively acylated over secondary alcohols with use of enol esters as acylating agents, methyl and ethyl esters can be employed as protective agents for secondary alcohols in the presence of the more active alkyl-substituted NHC catalysts. The NHC-catalyzed transesterification protocol was simplified by generating the imidazol-2-ylidene catalysts in situ.

A novel enzymatic route for biodiesel production from renewable oils in a solvent-free medium.

Abstract: A new enzymatic route for biodiesel production from soybean oil was developed using methyl acetate as a novel acyl acceptor. Novozym 435 (immobilized Candida antarctica lipase) gave the highest methyl ester (ME) yield of 92%. The optimum conditions of the transesterification were 30% enzyme based on oil weight; a molar ratio of methyl acetate/oil of 12:1; temperature 40 °C and reaction time 10 h. Since no glycerol was produced in the process, this method is very convenient for recycling the catalyst and by-product triacetylglycerol showed no negative effect on the fuel property.

Ethyl esters from the single‐phase base‐catalyzed ethanolysis of vegetable oils

Abstract: The effects of alcohol/oil molar ratio, base concentration, and temperature on the single-phase base-catalyzed ethanolyses of sunflower and canola oils were determined. The use of tetrahydrofuran as co-solvent, as well as higher than usual alcohol/substrate molar ratios, prevented glycerol separation. This allowed each reaction to reach equilibrium rather than just steady-state conditions. High conversions of oil lowered the concentrations of MG and DG surfactants in the products, and thereby mitigated the formation of emulsions usually associated with ethanolysis reactions. An alcohol/oil molar ratio of 25∶1, together with the necessary amount of cosolvent, gave optimal results. At this molar ratio, despite equilibrium being achieved, ethanolysis, unlike methanolysis, did not quite produce biodiesel-standard material, the MG content being approximately 1.5 mass%. For methanolysis and 1-butanolysis, the corresponding values were 0.6 and 2.0 mass%, respectively. The use of 1.4 mass% KOH (equivalent to 1.0 mass% NaOH) led to ethanolysis equilibrium within 6–7 min at 23°C rather than 15 min when only 1.0 mass% was used. At 60°C, equilibrium was reached within only 2 min. Soybean and canola oils behaved the same.

Direct Synthesis of Well-Defined Quaternized Homopolymers and Diblock Copolymers via ATRP in Protic Media

Abstract: The direct synthesis of well-defined cationic homopolymers and block copolymers based on methyl chloride-quaternized 2-(dimethylamino)ethyl methacrylate [MeDMA] by ATRP in protic media at 20 °C is described. Homopolymerization of MeDMA in purely aqueous media was fast and poorly controlled, leading to a relatively high polydispersity of 1.37 and low initiation efficiency. Addition of Cu(II)Br2 led to slower polymerizations but only slightly lower polydispersities. Addition of methanol also reduced the rate of polymerization and produced narrower molecular weight distributions. Unfortunately, 1H NMR studies indicated that transesterification of MeDMA with methanol produced significant quantities of methyl methacrylate (MMA) on the time scale of the polymerization; this side reaction led to the unwanted production of MeDMA−MMA statistical copolymers. This problem was alleviated by replacing the methanol cosolvent with 2-propanol, since the secondary alcohol was much less prone to transesterification. High c...

Enzymatic ester synthesis in ionic liquids

Abstract: Six different ionic liquids based on dialkylimidazolium or quaternary ammonium cations associated with perfluorinated or bis(trifluoromethyl)sulfonyl amide anions were used as reaction media for ester synthesis catalyzed by both free Candida antarctica lipase B and α-chymotrypsin at 2% (v/v) water content and 50 °C. All the assayed ionic liquids proved adequate media for enzyme-catalyzed transesterification, and in the case of lipase, the synthetic activity was clearly enhanced with respect to that obtained with organic solvents of similar polarity. In general, all the ionic liquids increased the thermal stability of both the enzymes. As for example, 1-ethyl-3-methylimidazolium tetrafluoroborate enhanced 5- and 4-times the synthetic activity and half-life time, respectively, of lipase in comparison to 1-butanol.

Lipase‐catalyzed alcoholysis of vegetable oils

Abstract: Fatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n-hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent-free reaction medium using methanol or 2-propanol as alcohol substrates. This could be overcome by a three-step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1-propanol, 1-butanol and isobutanol (50-65% conversion after 24 h) in solvent-free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.

Lipase-catalysed transesterification of soya bean oil for biodiesel production during continuous batch operation.

Abstract: The effects of temperature, oil/alcohol molar ratio and by-product glycerol were studied during Lipozyme TL IM-catalysed continuous batch operation when short-chain alcohols were used as the acyl acceptor. In non-continuous batch operation, the optimal oil/alcohol ratio and temperature were 1:4 and 40-50 degrees C; however, during the continuous batch operation, the optimal oil/alcohol ratio and temperature were 1:1 and 30 degrees C; 95% of enzymic activity remained after 10 batches when isopropanol was adopted to remove by-product glycerol during repeated use of the lipase.

New metal catalysts for soybean oil transesterification

Abstract: We report here the synthesis, characterization, and use of tin (3-hydroxy-2-methyl-4-pyrone)2(H2O)2, lead (3-hydroxy-2-methyl-4-pyrone)2 (H2O)2, mercury (3-hydroxy-2-methyl-4-pyrone)2-(H2O)2, and zinc (3-hydroxy-2-methyl-4-pyrone)2(H2O)2 as catalysts in the transesterification reaction of soybean oil with methanol. All complexes are active in this reaction, with the following decreasing activities: Sn2+≫Zn2+>Pb2+≈Hg2+. The catalytic activities of these complexes were also compared with classical alkali and acid transesterification catalysis (with NaOH and H2SO4).

1-Butyl-2,3-dimethylimidazolium tetrafluoroborate: the most desirable ionic liquid solvent for recycling use of enzyme in lipase-catalyzed transesterification using vinyl acetate as acyl donor

Abstract: 1-Butyl-2,3-dimethylimidazolium tetrafluoroborate ([bdmim]BF 4 ) was found to be an excellent solvent to realize a lipase-recycling system using vinyl acetate as acyl donor. No accumulation of an acetaldehyde oligomer was observed in this solvent system and it was possible to use the lipase repeatedly 10 times while still maintaining perfect enantioselectivity and high reactivity.

Poly(ester anhydride)s prepared by the insertion of ricinoleic acid into poly(sebacic acid)

Abstract: New degradable poly(ester anhydride)s were prepared by the melt polycondensation of diacid oligomers of poly(sebacic acid) (PSA) transesterified with ricinoleic acid The transesterification of PSA with ricinoleic acid to form oligomers was conducted via a melt bulk reaction between a high molecular weight PSA and ricinoleic acid A systematic study on the synthesis, characterization, degradation in vitro, drug release, and stability of these polymers was performed Polymers with weight-average molecular weights of 2000-60,000 and melting temperatures of 24-77 °C were obtained for PSA containing 20-90% (w/w) ricinoleic acid NMR and IR analyses indicated the formation of ester bonds along the polyanhydride backbone These new degradable copolymers have potential use as drug carriers

Preparation and properties of lubricant basestocks from epoxidized soybean oil and 2-ethylhexanol

Abstract: Synthetic lubricant basestocks were prepared from epoxidized soybean oil (ESO) and 2-ethylhexanol (2-EH) to be used alone or with polyalphaolefin (PAO). Sulfuric acid-catalyzed reaction of ESO with 2-EH involves a ring-opening reaction at the epoxy group followed by transesterification at the ester group. Reaction with other catalysts including p-toluenesulfonic acid, Dowex 50W-8X, boron trifluoride, and sodium methoxide was also examined. Pour points of the products were observed as lows as −21 and −30°C without and with 1% of pour point depressant, respectively. When the hydroxy groups in the products were esterified with an acid anhydride, lower pour points were observed. Pour point depression of the product by adding PAO has been tested. Oxidative stability of the product was examined using pressurized DSC and compared with those of synthetic lubricant basestocks, PAO, and a synthetic ester.

Enzymatic transesterification for biodiesel production.

Abstract: Biodiesel consists monoalkyl esters of long chain fatty acids It is produced from vegetable oils or fats either by chemical transesterification or by lipase-catalyzed transesterification with methanol or ethanol Biodiesel is a green fuel and can be used as a blend with diesel or alone Either way, it does not require any modification in engine design or storage facilities The enzymatic process offers several advantages over the chemical routes The handicap of increase in process cost because of the cost of the enzyme can be overcome by using efficient production process for enzyme and using reusable derivatives of enzymes, such as immobilized enzyme Numerous strategies available in the area of non-aqueous enzymology can be exploited during the enzymatic alcoholysis for biodiesel production Some of the technical challenges and their possible solutions are also discussed

Noncatalytic Alcoholysis Kinetics of Soybean Oil

Abstract: Reaction kinetics for the alcoholysis of soybean oil with methanol, ethanol, and isopropanol were evaluated in the absence of catalyst. Metal reactor surfaces catalyzed these reactions, so the reactions were conducted in glass capillary tubes at 120, 150, and 180°C. The reactivity of the alcohols increased with decreasing carbon number. Higher temperatures promoted faster reactions. Higher alcohol stoichiometries did not significantly increase reaction rates; this was attributed to the limited solubility of the alcohol in the soybean oil. At less than 20% conversion, the solubility of the alcohol in the oil phase continuously increased, resulting in increased reaction rates. At approximately 20% conversion, the reaction systems became homogeneous until a glycerine phase was formed at high conversions. In addition to their fundamental value, these data provided a basis on which catalytic reactions can be investigated between 100 and 200°C.

Solid-Phase Synthesis of Indolecarboxylates Using Palladium-Catalyzed Reactions

Abstract: Polymer-supported, palladium-catalyzed cyclization reactions effectively synthesized indolecarboxylates. Palladium-catalyzed carbon−carbon bond-forming reactions of immobilized enaminoesters followed by transesterification yielded indole 2- or 3-carboxylates with various functional groups on the benzene ring. Indolecarboxylates were efficiently cyclized via an intramolecular palladium-catalyzed amination reaction of immobilized N-substituted dehydrohalophenylalanines, and immobilized N-acetyl-dehydroalanines were efficiently converted into indolecarboxylates via tandem Heck−amination reactions.

Enzymatic production of fatty acid alkyl esters with a lipase preparation from Candida sp. 99-125.

Abstract: A lipase preparation developed from Candida sp. 99-125 was used for fatty acid alkyl ester synthesis by both enzymatic esterification of fatty acids, and transesterification of oils and fats. The lipase preparation was chosen based on screening of lipases from commercial sources as well as those produced in the laboratory. The effects of enzyme dosage, solvent types, water absorbent additions, inhibition of short-chain alcohols, alcohol and acid types, molar ratio of substrates, and reusability of the lipase preparation in esterification were studied. Degree of esterification between oleic acid and methanol under optimal conditions reached 92%. Purity of the methyl ester after washing with water and distillation was 98%. Half-life of the lipase preparation was calculated to be approximately 340 h. For transesterification of rapeseed oil with the same lipase preparation, the amount of methanol and mode of methanol addition to the reaction were also conducted. Transesterification of the oil with stepwise methanol addition reached 83% after 36 h reaction time.

Direct Degradation of the Biopolymer Poly[(R)‐3‐Hydroxybutyric Acid] to (R)‐3‐Hydroxybutanoic Acid and its Methyl Ester

Abstract: Direct degradation of the biopolymer poly[(R)-3-hydroxybutyric acid] to (R)-3-hydroxybutanoic acid and its methyl ester product: (R)-(−)-methyl 3-hydroxybutanoate product: (R)-3-hydroxybutanoic acid Keywords: hydrolysis, esters and lactones; reduction, CO CHOH; stereoselective reactions, enantioselective; transesterification; chloroform, highly toxic, cancer suspect agent

Development of optimum synthesis method for transesterification of palm oil methyl esters and trimethylolpropane to environmentally acceptable palm oil-based lubricant

Abstract: Chemical synthesis of palm oil trimethylolpropane esters was conducted via transesterification of palm oil methyl esters (POME) with trimethylolpropane (TMP). The palm oil TMP esters are potential biodegradable base stock for lubricant production. The influence of the main operating variables, namely, temperatures and pressures, molar ratio of palm methyl esters to TMP, and catalyst amount was studied and analysed. The effects of temperature (80oC to 140oC) and reduced pressure (0.1, 10, 50, 100 and 500 mbar) were investigated and found to have a significant impact on the reaction. On the contrary, the amount of catalyst (% w/w) and molar ratio of POME to TMP had little influence on the conversion but affected the overall yield of the reaction. The optimal reaction conditions are as follows: duration: 1 hr; temperature: 130°C; pressure: 20 mbar; catalyst: sodium methoxide at 0.8% w/w; molar ratio of POME:TMP at 3.9:1. Palm oil TMP ester containing 98% w/w triesters was successfully synthesized in less than an hour.

Synthesis of glycerol monostearate with high purity

Abstract: Samgwang Goha Chem Co., Ltd, 571 Yongje-dong, Iksan 570-350, KoreaReceived January 27, 2003Key Words : Glycerol monostearate, Amberlyst 15, 1,2-O-Isopropylideneglycerol, Transesterification,Deprotection of acetonideGlycerol monoesters synthesized from glycerol have manyapplications, such as emulsifying agents in food, phar-maceuticals, cosmetics, or in detergents.

Toolbox for exchanging constituent fatty acids in lecithins

Abstract: Since the compositional variety of phospholipids in native lecithins is limited, and structurally diverse synthetic phospholipids are expensive, the aim of this work was to develop a lecithin modification toolbox capable of modifying the fatty acid composition of native lecithins at a convenient lab-scale of 10-100 g. Starting with the native phospholipids of soybean lecithin, two types of fatty acid modification were carried out using either phospholipase A2 from porcine pancreas or a lipase from Rhizopus oryzae. The former was immobilised onto celite and used to selectively hydrolyse the sn-2 positioned fatty acid and the latter, commercially available in an immobilised form, was used to transesterify novel fatty acids onto the sn-1 position. The degree of phospholipid hydrolysis could be controlled between 5 and 95% by varying the contact time with the biocatalyst. A key parameter was the water concentration. By avoiding the presence of a bulk phase of water, emulsion formation was prevented and so simple product recovery was possible. However, sufficient water was required in order to maintain the water activity above 0.2, and because phospholipids increased the polarity of the solvent (hexane), it was necessary to add water in proportion to the lecithin concentration. During transesterification with methyllaurate, up to 43% lauric acid could be incorporated and although the recovery of fully acylated phospholipids was only 28%, due to the formation of hydrolysis products, they were isolated using solvent partitioning in hexane/isopropanol/water. The temperature was important in determining the relative rates of hydrolysis and transesterification and a lower temperature (40 °C) was favourable as the rate of hydrolysis was lowered without affecting the rate of transesterification.