Kinetics Of Esterification Research Articles

Kinetics of esterification of lauric acid with fatty alcohols by lipase: effect of fatty alcohol

AbstractLauric acid has been esterified with some C1–C18 aliphatic alcohols by a commercial lipase, Lipolase 100 L, using isooctane as a solvent. When lauric acid and fatty alcohols were taken in the mole ratio 1:1, first order kinetics were observed for all the alcohols studied. The highest reaction rate was observed for n‐butyl alcohol. Lauric acid was esterified with stearyl alcohol, in varying acid to alcohol mole ratios to explain the first order kinetics of the reaction. A kinetic model for the lipase‐catalysed esterification in a biphasic organic–aqueous system has been proposed. Based on the interfacial substrate concentration, an analytical rate equation for initial rate of the reaction was derived and confirmed with the experimental data.© 2002 Society of Chemical Industry

Autocatalyzed and Ion-Exchange-Resin-Catalyzed Esterification Kinetics of Lactic Acid with Methanol

The esterification kinetics of lactic acid with methanol without addition of catalyst and catalyzed by ion-exchange resins are presented in this work. The effect of catalyst type, stirrer speed, catalyst size, catalyst loading, initial reactant ratio, and temperature on reaction kinetics was evaluated. Experimental reaction rates were correlated by some models based on homogeneous and heterogeneous (dual- and single-site mechanisms) approaches. Nonideality of the liquid phase was taken into account by using activities instead of mole fractions. Prediction of the activity coefficients was made by UNIFAC. Parameters of the different models were obtained by the simplex search method.

Kinetics of esterification of propanoic acid with methanol over a fibrous polymer-supported sulphonic acid catalyst

Esterification kinetics of propanoic acid with methanol in the presence of a fibrous polymer-supported sulphonic acid catalyst as well as a conventional resin catalyst was studied. Kinetic experiments were carried out in a laboratory-scale batch reactor operating isothermally at 55, 60 and 63 °C and with different initial molar ratios of propanoic acid and methanol (1:1, 2:3 and 3:2). The fibre catalyst was active and stable in all the experiments. A reference experiment with the conventional catalyst, Amberlyst 15 was carried out at 60 °C, with the initial molar ratio 1:1. The reaction rate was higher with the fibre catalyst than with the Amberlyst 15. The apparent second-order rate constant for the fibre catalyst was 1.82×10 −3 dm 9/(mol 2 g min) at 60 °C with the initial molar ratio 1:1 and 7.03×10 −4 dm 9/(mol 2 g min) for the conventional catalyst under comparable conditions. The fibre catalyst was re-used in four experiments to explore its durability. After four successive experiments, the catalyst activity and capacity remained on the initial level, indicating good stability. A new kinetic model comprising the adsorptive interaction of propanoic acid and water with the sulphonic acid groups on the catalyst surface was developed and tested with the experimental data. The new rate equation gave a good fit to the data and was able to describe the behaviour of the system at various initial molar ratios of propanoic acid and methanol.

Kinetic studies of lipase-catalyzed esterification in water-in-oil microemulsions and the catalytic behavior of immobilized lipase in MBGs

The esterification kinetics of octanoic acid with 1-octanol, catalyzed by Candida lypolytical (CL) lipase, was studied in water-in-oil microemulsions formed by water/bis-(2-ethylhexyl)sulfosuccinate sodium (AOT)/isooctane. Kinetic studies showed that the reaction follows a Ping-Pong Bi Bi mechanism with inhibition by excess of 1-octanol. The values of all apparent kinetic parameters were determined to be v max=4.7×10 −3 mmol l −1 min −1 mg −1, K m acid=49.3 mmol l −1, and K m alcohol=47.6 mmol l −1, respectively. CL lipase has also been immobilized in gelatin-containing AOT microemulsion-based organogels (MBGs) with retention of catalytic activity. These lipase-containing MBGs were proved to be a novel solid-phase catalyst for use in apolar organic solvents. The behavior of this novel, predominantly hydrophobic matrix as an esterification catalyst was also examined.

The effect of ethanol on the kinetics of lipase-mediated enantioselective esterification of 4-methyloctanoic acid and the hydrolysis of its ethyl ester.

The Novozym 435(R) catalyzed esterification and hydrolysis reactions of 4-methyloctanoic acid (ethyl ester) were investigated. In both the hydrolysis and esterification reactions, the increase of ethanol concentration led to an increase in enantiomeric ratio (E). For hydrolysis of the ethyl ester, the E-value increased from 5.5 [0% (v/v) EtOH] up to 12 [20% (v/v) EtOH]. In case of esterification, the E-value was already 16 [14% (v/v) EtOH] and rose to 57 [73% (v/v) EtOH]. When combining these results of esterification and hydrolysis, an enantiomeric ratio of 350 can be estimated for the sequential kinetic resolution of 4-methyloctanoic acid. In this way, enantiopure 4-methyloctanoic acid could be obtained after two consecutive reaction steps.

Decreased hepatic accumulation and enhanced esterification of cholesterol in mice deficient in mdr1a and mdr1b P-glycoproteins

Class I P-glycoproteins [Pgp; MDR1 (ABCB1) in humans, mdr1a and mdr1b in mice] confer resistance to structurally diverse chemotherapeutic drugs in cultured cells and intact animals, but the function of these proteins in normal physiology remains poorly characterized. Based on studies in cell culture, a putative role for class I Pgp in absorption and intracellular trafficking of sterols has been proposed. We examined wild-type and mdr1a−/−/1b−/− mice to determine whether class I Pgp affects cholesterol absorption and esterification in vivo. Using a dual-isotope protocol, absorption of orally administered radiolabeled cholesterol into serum did not differ between wild-type and mdr1a−/−/1b−/− mice, demonstrating that class I Pgp is not essential for overall absorption of cholesterol through the intestine. However, the ratio of oral to intravenous labeled cholesterol in liver was decreased significantly in mdr1a−/−/1b−/− mice. In the liver, but not other tested organs, deletion of class I Pgp enhanced kinetics of esterification of an oral bolus of radiolabeled cholesterol without affecting esterification of cholesterol administered intravenously. Steadystate hepatic content of cholesterol and esterified cholesterol also were unaffected by absence of mdr1a and mdr1b. Thus, in normal animals, class I Pgp functions to kinetically increase hepatic accumulation and decrease esterification of orally administered cholesterol in vivo. —Luker, G. D., J. L. Dahlheimer, R. E. Ostlund, Jr., and D. Piwnica-Worms. Decreased hepatic accumulation and enhanced esterification of cholesterol in mice deficient in mdr1a and mdr1b P-glycoproteins.

Reaction Kinetics of Lactic Acid Esterification with Methanol Noncatalyzed and Catalyzed by Ion-Exchange Resins

Chemie Ingenieur TechnikVolume 73, Issue 6 p. 662-662 Article Reaction Kinetics of Lactic Acid Esterification with Methanol Noncatalyzed and Catalyzed by Ion-Exchange Resins M.T. Sanz, M.T. Sanz Department of Chemical Engineering. University of Burgos.Search for more papers by this authorS. Beltrán, S. Beltrán Department of Chemical Engineering. University of Burgos.Search for more papers by this authorJ.L. Cabezas, J.L. Cabezas Department of Chemical Engineering. University of Burgos.Search for more papers by this author M.T. Sanz, M.T. Sanz Department of Chemical Engineering. University of Burgos.Search for more papers by this authorS. Beltrán, S. Beltrán Department of Chemical Engineering. University of Burgos.Search for more papers by this authorJ.L. Cabezas, J.L. Cabezas Department of Chemical Engineering. University of Burgos.Search for more papers by this author First published: 12 July 2001 https://doi.org/10.1002/1522-2640(200106)73:6<662::AID-CITE6624444>3.0.CO;2-4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume73, Issue6Juni 2001Pages 662-662 RelatedInformation

Lipase-catalyzed synthesis of isoamyl butyrate: A kinetic study

Kinetics of lipase-catalyzed esterification of butyric acid and isoamyl alcohol have been investigated. The reaction rate could be described in terms of the Michaelis–Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. No evidence of any significant diffusional limitations was detected that could affect the kinetics. The values of the apparent kinetic parameters were computed as: V max=11.72 μmol/min/mg; K M, Acid=0.00303 M; K M, Alcohol=0.00306 M; K i, Acid=1.05 M; and K i, Alcohol=6.55 M. This study indicates a competitive enzyme inhibition by butyric acid during lipase-catalyzed esterification reaction. Butyric acid, being a short-chain polar acid, concentrates in the microaqueous layer and causes a pH drop in the enzyme microenvironment leading to enzyme inactivation. Butyric acid binds to acyl–enzyme complex unproductively to yield a dead-end intermediate that can no longer give rise to an ester. High concentration of butyric acid gave rise to inactivation of the biocatalyst in addition to dead-end inhibition.

Kinetics of phase-transfer catalyzed esterification of aliphatic dicarboxylate in solid–liquid system

The kinetics of synthesizing sebacic acid dibenzyl ester used as plasticizer or lubricant was investigated for the esterification of solid dipotassium sebacate with benzyl bromide via phase-transfer catalysis in a solid–liquid system. Without the addition of catalysts in a stirred batch reactor, no products were observed after 4 h at 80°C. If one employs tetra- n-butylammonium bromide as the catalyst during this esterification of the aliphatic dicarboxylate, a product yield above 60% can be achieved for the same operating conditions. Factors affecting the efficiencies of the phase-transfer catalysts were explored to search for the reaction mechanism. A mechanism based on the concept of topochemical reaction in phase-transfer catalysis and homogeneous solubilization with a transition complex was proposed. The kinetic model was set up to describe the catalytic behaviors successfully for the overall reaction during and after the induction period.

Effect of electrode parameters on charge performance of a lead-acid cell

Kinetics of lipase-catalyzed esterification of butyric acid and isoamyl alcohol have been investigated. The reaction rate could be described in terms of the Michaelis–Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. No evidence of any significant diffusional limitations was detected that could affect the kinetics. The values of the apparent kinetic parameters were computed as: Vmax=11.72 μmol/min/mg; KM, Acid=0.00303 M; KM, Alcohol=0.00306 M; Ki, Acid=1.05 M; and Ki, Alcohol=6.55 M. This study indicates a competitive enzyme inhibition by butyric acid during lipase-catalyzed esterification reaction. Butyric acid, being a short-chain polar acid, concentrates in the microaqueous layer and causes a pH drop in the enzyme microenvironment leading to enzyme inactivation. Butyric acid binds to acyl–enzyme complex unproductively to yield a dead-end intermediate that can no longer give rise to an ester. High concentration of butyric acid gave rise to inactivation of the biocatalyst in addition to dead-end inhibition.

Kinetic characterisation of enzymatic esterification in a solvent system: adsorptive control of water with molecular sieves

The kinetics of enzymatic esterification of glycerol with oleic acid, in equimolar ratio, catalyzed by immobilized Mucor miehei lipase in a solvent system in the presence of the molecular sieves was carried out at 37°C at different Lipozym and solvent (n-hexane) concentrations and the molecular sieve contents were studied in a batch stirred-tank reactor (BSTR). The reactions were followed by the determination of reaction conversions during 45 h. The experimental data of enzymatic esterification of glycerol with oleic acid in a solvent system in the presence of molecular sieves showed minimal deviation from the calculated value in the irreversible second order kinetic model. On the basis of the experimental data, we found an empirical correlation between concentrations of Lipozym, concentrations of solvent (n-hexane), contents of the molecular sieve and the reaction rate constant, k1.

Kinetics of Catalytic Esterification of Acetic Acid with Amyl Alcohol over Amberlyst 15.

Kinetic behavior was investigated in an isothermal fixed-bed reactor for the catalytic esterification of acetic acid with amyl alcohol over Amberlyst 15, an acidic cation exchange resin. Both chemical equilibria and phase behavior of the reacting mixtures were also observed under different feed compositions. Four kinetic models, including the pseudo-homogeneous, the Langmuir-Hinshelwood, the Eley-Rideal, and a modified Langmuir-Hinshelwood, were applied to correlate the kinetic data at temperatures between 303.15 and 353.15 K and molar ratios of feed (amyl alcohol to acetic acid) from 1 to 15. The capabilities of these models were compared.

Lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol

The influences of water activity and solvent hydrophobicity on the kinetics of the lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol were investigated. The solvent effect was not similar for lipases from Candida rugosa (Crl), Mucor javanicus (Mjl), and porcine pancreas (Ppl). The lipase-catalyzed reaction rates in different solvents across a wide range of water activities revealed that the Ppl-catalyzed reaction exhibited no enantioselectivity and no substantial water activity or solvent dependence. The Mjl-catalyzed reaction proceeded faster, preferring the R-enantiomer reaction over that of its antipode, but had little solvent or water activity dependence. The Crl-catalyzed reactions in n-heptane and n-nonane had similar water activity dependence, but the reaction was considerably faster and more enantioselective (preferring the S-enantiomer reaction) in isooctane, a solvent whose hydrophobicity is intermediate between that of the other two alkanes. Substrate enantiomeric excess, for the Crl-catalyzed reaction at 96 hours and at a water activity of 0.65, in n-heptane, isooctane, and n-nonane was 40.9, 93.0, and 50.0%, respectively. Since the three solvents possess similar physical properties, the explanation for this anomalous behavior might be the effect of the solvent structural characteristics on Crl, since isooctane is the only branched alkane.

Lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol

The influences of water activity and solvent hydrophobicity on the kinetics of the lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol were investigated. The solvent effect was not similar for lipases from Candida rugosa (Crl), Mucor javanicus (Mjl), and porcine pancreas (Ppl). The lipase-catalyzed reaction rates in different solvents across a wide range of water activities revealed that the Ppl-catalyzed reaction exhibited no enantioselectivity and no substantial water activity or solvent dependence. The Mjl-catalyzed reaction proceeded faster, preferring the R-enantiomer reaction over that of its antipode, but had little solvent or water activity dependence. The Crl-catalyzed reactions in n-heptane and n-nonane had similar water activity dependence, but the reaction was considerably faster and more enantioselective (preferring the S-enantiomer reaction) in isooctane, a solvent whose hydrophobicity is intermediate between that of the other two alkanes. Substrate enantiomeric excess, for the Crl-catalyzed reaction at 96 hours and at a water activity of 0.65, in n-heptane, isooctane, and n-nonane was 40.9, 93.0, and 50.0%, respectively. Since the three solvents possess similar physical properties, the explanation for this anomalous behavior might be the effect of the solvent structural characteristics on Crl, since isooctane is the only branched alkane.

Kinetics of Catalytic Esterification of Acetic Acid and Amyl Alcohol over Dowex

The kinetic behavior of the heterogeneous esterification of acetic acid with amyl alcohol over an acidic cation-exchange resin, Dowex 50Wx8-100, was investigated. The experiments were conducted in a fixed-bed reactor at temperatures from 323 to 393 K and at molar ratios of feed (amyl alcohol to acetic acid) from 1 to 10. The equilibrium conversion of acetic acid was found to increase with increasing reaction temperature. A water-rich phase (the second liquid phase) appeared in the reacting mixture when the feed composition was close to stoichiometric. Gas bubble formation was observed when the reaction temperature was as high as 393 K. The kinetic data were correlated with the quasi-homogeneous, Langmuir−Hinshelwood, Eley−Rideal, and modified Langmuir−Hinshelwood models. The modified Langmuir-Hinshelwood model yielded the best representation for the kinetic behavior of the reaction over wide ranges of temperature and feed composition.

Esterification of oleic acid and ethanol in plug flow (packed bed) reactor under supercritical conditions: Investigation of kinetics

The present work provided the reaction kinetic data, required to predict the performance of packed-bed plug flow bioreactor operating under supercritical conditions. It investigated the kinetics of esterification of oleic acid and ethanol. Biocatalyst Lypozyme™ IM60, which is lipase from Rhizomucor miehei immobilised on Duolite (an ion exchange resin), was employed to synthesise ethyl oleate. Experimentally, esterification was carried out using a range of oleic acid- and ethanol concentrations, respectively. The effect of water concentration on the enzyme activity was also investigated. Analytically, the reaction mechanism was investigated by a series of kinetic analysis using the Direct Linear, the Primary and the Burke–Lineweaver (double reciprocal) plots. The reaction was modelled by the Henri–Michaelis–Menten equation and the reaction constants, namely K m and V max, were evaluated. It was found that the initial water concentration in the system effected the enzyme initial activity in a bell-like manner, giving an optimum (enzyme activity,and water concentration) value for each alcohol concentration. Furthermore, it was found that under higher alcohol concentrations, the reaction experienced substrate inhibition. The latter was identified to be competitive inhibition under moderate alcohol concentrations and non-competitive inhibitions under high alcohol concentrations. Hence, reaction inhibition constant value K i was calculated.

Lipase-facilitated separation of organic acids in a hollow fiber contained liquid membrane module

A lipase-facilitated selective and continuous separation of difficult-to-separate mixtures of organic acids has been developed in a hollow fiber contained liquid membrane (HFCLM) device. The device consists of a well-mixed two-fiber-set hydrophobic microporous polypropylene hollow fiber membrane module where lipase from Candida rugosa (CRL) and lipase from porcine pancreas (PPL) were immobilized on the internal diameter of two identical sets of hollow fibers, respectively. The module shell side contained 20 v/v% octanol in n-heptane acting as the organic liquid membrane between the two commingled fiber sets. Two systems of model acid mixtures were selected to demonstrate this technique: (1) phenylacetic acid (PAA) and mandelic acids (MAs); (2) PAA and 6-aminopenicillanic acid (6-APA). Aqueous feed solution containing the acid mixtures and ethanol flowed through one fiber set; a stripping aqueous solution flowed through the second fiber set and was highly enriched in PAA. The separation factors of PAA over MAs and PAA over 6-APA were as high as 20 and 10, respectively. The esterification kinetics of PAA and ethanol catalyzed by CRL in batch experiment yielded V max and K m′ values to be 0.139 mmol/(h(mmol) CRL) and 62.2 mM, respectively. Much higher enzyme activities and enzyme stability were achieved in the HFCLM device due to immobilization of the lipases on the hydrophobic membrane surface where the organic–aqueous interface was immobilized and the ester produced was simultaneously transferred into the organic liquid membrane. The transport rate of PAA in the HFCLM device was 224 times higher than the V max measured in batch experiments.

Esterification kinetics in titanium isopropoxide-acetic acid solutions

FTIR observation has been used to analyze the reaction between titanium isopropoxide and acetic acid under a variety of conditions. Isopropyl acetate ester forms in these mixtures and serves as an indicator of the extent of condensation between the titanium precursors. Condensation occurs to a gradually increasing extent to form a broad spectrum of titanium oxo-acetate polymers. The temperature dependence of the time to reach observable precipitation in these solutions has also been mapped out. The activation energy for this process was found to be 0.7 eV. The precipitation times have a direct bearing on how these solutions can be used when making a wide variety of titanium containing sol-gel solutions.

Kinetics of Esterification of Lactic Acid with Methanol in the Presence of Cation Exchange Resin Using a Pseudo-Homogeneous Model.

The kinetics of esterification of lactic acid with methanol in the liquid phase are studied by using a cation exchange resin in the H+ form (DOWEX-50W) as an acid catalyst. Experiments were carried out in a stirred batch reactor at different temperatures (323, 333, 343, 353 K) under atmospheric pressure. The effects of reaction temperature and catalyst loading on the reaction rate are investigated. It is found that catalyst size and stirring speed have no significant effects on reaction rate. The reaction rate data are correlated with a kinetic model based on pseudo-homogeneous catalysis. The activity of resin is compared with that of sulfuric acid as a catalyst. A kinetic equation for describing the reaction catalyzed by cation exchange resin is developed.

Lipase-catalysed esterification of oleic acid and ethanol in a continuous packed bed reactor, using supercritical CO2 as solvent: approximation of system kinetics

This work investigated the immobilised lipase kinetics of esterification of oleic acid and ethanol. The reaction was conducted under supercritical conditions (13 × 106 Pa and 40 °C) using carbon dioxide as solvent in a continuous packed bed (plug flow) reactor. Biocatalyst LypozymeTM IM60, which is lipase from Rhizomucor miehei (EC.3.1.1.3), immobilised on Duolite (anionic exchange resin) was used as biocatalyst. Kinetically, with regard to oleic acid, the reaction was successfully modelled by the Michaelis–Menten mechanism. The reaction rate constants Km and Vmax were evaluated. Furthermore, it was found to undergo competitive inhibition by ethanol, and the inhibition constant Ki was evaluated. © 2000 Society of Chemical Industry