• Journal of the Korean Applied Science and Technology
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• v.10 no.1
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• pp.67-74
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• 1993

1, 2-Isopropylidene glycerol produced by ketalyzation of glycerol with aceton was esterified with long chain fatty acids in the presence of a Mucor miehei lipase to obtain 1, 2-isopropylidene 3-long chain acyl glycerol. To determine optimal conditions for the esterification reaction, esterification was proceeded as a reversible second-order reaction in various parameters that are enzyme/substrate ratio 0.096g/g at reaction temperatures ranged from $25^{\circ}C$ to $70^{\circ}C$. The order of reaction rate of fatty acids were lauric acid, myristic acid, oleic acid, and stearic acid. The range of their activation energies were from 7.8 to 11.4 (kcal/mol) and that of entropies of activation which have negative values were from 42.8 to 52.5(e.u.).

• Membrane Journal
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• v.17 no.2
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• pp.146-160
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• 2007

A parametric study on pervaporation-facilitated esterification was performed by using a practical model based on non-perfect separation through membrane which is not perfectly permselective to water. Thus, membrane selectivity as well as membrane capability to remove water should be taken into account in establishing the simulation model to explain how the membrane separation influence the esterification reaction process. It was shown by simulation that in the reaction systems with non-perfect separation, the permeation of reactants which are acid or/and alcohol retards the reaction by inducing the backward reaction so that reaction conversion curve is located between a reaction system coupled with pervaporation process having a perfect permselectivity to water and a reaction system without pervaporation process. The volume change of reaction system occurs as a result of the permeation through the membrane. The reaction volume change which can be characterized by the reaction ratio of $r_{\Psi}\;to\;r_{{\Psi}=1}$ affects reaction kinetics by concentrating reactants and products, respectively, with different extent with time; reactant-concentrating effect is dominant during the initial stage of reaction, resulting in facilitating the reaction, and then product-concentrating effect is exerted more on reaction, causing to slow down the reaction. When pervaporative dehydration is applied to the reaction system plays an important role in the reaction as well. The effect of timing to impose pervaporation on reaction system affected the reaction kinetics in terms of reaction rate and reaction conversion. A relationship was derived to explain membrane unit capacity and reaction parameters that will be used as a design tool to determine membrane unit capacity at a given reaction conditions or reaction parameters at a membrane unit capacity.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.643-649
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• 2007

Lipase-catalyzed esterification of structural butanol isomers and n-butyric acid was investigated in supercritical carbon dioxide. The experiments were performed in a high pressure cell for 5 hrs with a stirring rate of 150 rpm at 323.15 K and 130 bar. The Candida Antarctica lipase B (CALB) was used in whole system as a catalyst. The experimental results were analyzed by GC-FID using a INNOWax capillary column. The conversion yield and the tendency of the esterification in supercritical carbon dioxide were compared with estimated results by molecular dynamics simulation. Based on the Ping-Pong Bi-Bi mechanism with competitive inhibition, each step of the reaction was optimized; using this result the transition state was predicted. Conformational preference of isomers was also analyzed using molecular dynamics simulations. This kind of approach will be further extended to the prediction of enzyme-catalyzed reactions using computers.

• Journal of Pharmaceutical Investigation
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• v.33 no.1
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• pp.37-43
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• 2003

The objective of this study is to prepare ketoprofen (KP) - poly(ethylene glycol) (PEG) conjugates and to investigate their degradation kinetics. KP-PEG conjugates were synthesized from KP and PEG methy1ester by esterification in the presence of DCC. The KP-PEG conjugates (KPEG) were characterized by IR and $^{1}H-NMR$ spectroscopy. The hydrolysis of KPEG with time was studied using HPLC by simultaneous quantification of KP and KPEG. The hydrolysis rate constant was high at low and high pHs, and showed minimum at pH 4 and 5. As the size of KPEG increases, hydrolysis rate increased. The slope of degradation rate profile suggests that catalytic reaction seems to occur by specific acid/base catalysis. These results suggest that KPEG could be used as a prodrug for KP, which releases KP slowly in the body.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.79-88
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• 1999

The stability and performance (peel strength) of the acrylic copolymer and various modified rosin systems were investigated. The peel strength was measured over a wide range of scaling rates, and the influence of the viscoelasticity of the PSA(pressure sensitive adhesive) was considered. In the case of miscible systems, the peak of peel strength (PSA performance) over wide peel rates was changed and modified systematically with increasing glass transition temperature of the blends. The peak of the peel strength for blended systems shifts toward the lower rate side as glass transition temperature ($T_g$) of the blend increased. The influence of esterification of the rosin on performance and stability against deterioration was greatly modified by blending with rosin of glycerol ester and rosin pentaerythritol ester. The failure mode of the blend varies with the combination with acrylic copolymer and modified rosin, and cohesive failure was found at a lower peel rate while interfacial failure was found at a high peel rate. A few systems where a single Tg could be measured, despite the fact that two phases were observed microscopically, were detected.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.797-802
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• 2003

Structured lipids (SL) were synthesized by esterification of corn oil and conjugated linoleic acid (CLA) in a continuous packed-bed column reactor. The effects of flow rate, reaction temperature, and substrate molar ratios were studied. The reaction was catalyzed by TL IM (immobilized lipase from Thermomyces lanuginosa). Results of triacylglycerol (TAG) analysis by GC showed that the incorporated CLA isomers were mainly cis9, trans11- and trans 10, cis12-CLA. Slower flow rates yielded higher incorporation, and maximum incorporation of CLA was obtained with a molar ratio of 1:3 (corn oil: CLA) at a temperature of $55^{\circ}C$. The obtained SLs had iodine values ranging from 120 to 128. The SLs were composed of TAG $(98{\sim}99%)$, 1,2- and 1,3-diacylglycerol ($0.7{\sim}1.3%$), and a small amount of monoacylglycerol.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.452-456
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• 2010

It is known that 1,3-diglyceride (1,3-DG) hardly accumulates inside human body because the metabolism of 1,3-DG is entirely different from that of general fats such as triglycerides (TG). This research focuses on the selective synthesis of 1,3-DG by the esterification reaction using an immobilized lipase. For a reaction between glycerin and oleic acid (OA) with a mole ratio of 1 : 2 under vacuum, changes in the compositions of monoglyceride (MG), TG and DG and the contents of 1,3-isomers in DG were investigated, as a function of reaction temperature and the amount of lipase. The reactivities determined by the rate of the consumption of OA became higher with the increase in temperature and the amount of lipase. When the results were compared with those obtained in the earlier study where Novozym was applied as an immobilized lipase, the reactivity was higher for Novozym, on the other hand, selectivity to 1,3-DG was much higher for Lipozyme. Especially, it is remarkable that 1,3-DG content in total DG reached to 98% in the reaction carried out at $50^{\circ}C$ using Lipozyme.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.443-448
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• 2009

It is known that 1,3-diglyceride (1,3-DG) hardly accumulates inside human body because the metabolism of 1,3-DG is entirely different from that of general fats such as triglycerides (TG). This research focuses on the selective synthesis of 1,3-DG by the esterification reaction using an immobilized lipase. For a reaction between glycerin and oleic acid (OA) with a mole ratio of 1 : 2 under vacuum, changes in the compositions of monoglyceride (MG), TG and DG and the contents of 1,3-isomers in DG were investigated, as a function of reaction temperature and the amount of lipase. The reactivities determined by the rate of the consumption of OA became higher with increased in temperature and the amount of lipase. Changes in the compositions of MG, DG and TG, however, occurred after the DG content reached maximum, which were found to be dependent on various factors. TG was a main product, and significant decrease in the amount of both 1,3-DG and DG were observed, when reactions were carried out at high temperatures or when 10 wt% of lipase was used.

• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.398-408
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• 2020

The purpose of the present study was to investigate the mechanism of metabolic partitioning between oxidization and esterification of liver fatty acids synthesized and secreted by the liver from egg yolk-fed laboratory rats. Animals were divided into four groups and orally administered egg yolk daily for 30 days: CON (control group, 1.0 g of saline solution), T1 (1.0 g of pork belly oil), T2 (1.0 g of egg yolk), and T3 (1.0 g of pork belly oil and 1.0 g of egg yolk, alternatively each week). The accumulation rate of [¹⁴C]-labelled lipid in liver was lowest in T2 among all treatments (P<0.05). Phospholipid secretion was higher in T2 than other treatments (P<0.05). The triglycerol secretion was highest in T1 and higher in the order of CON, T3, and T2 (P<0.05). Metabolic partitioning rate of phospholipid from total glycerolipid was highest in T2, followed by T3, CON and T1 (P<0.05). The ¹⁴CO₂ production from total glycerolipid was the highest in T2 and showed a high oxidation rate compared to CON, T1, and T3 (P<0.05). Metabolic partitioning of glycerolipid from the liver decreased in triglycerol of T2 compared to CON, T1, and T3, whereas phospholipids of T2 increased (P<0.05).

• Elastomers and Composites
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• v.46 no.1
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• pp.37-44
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• 2011

Effect of organo nanoclay (Cloisite 30B) on the polyesterification of adipic acid (AA) with diethylene glycol(DEG) was investigated with p-toluene sulfonic acid (p-TSA) (Br${\phi}$nsted acid) and butylchlorotin dihydroxide (Lewis acid) catalyst at 383 and 423 K. The initial [OH]/[COOH] molar ratio was two and the concentration of the catalysts in the reactants was 0.14 mol% based on the total reactants. The kinetics of the polyesterification was interpreted with the conversion data that was calculated from the acid values of the reactant-product mixture. The reaction rate of the polyesterification, which was catalyzed with p-TSA, exhibited the second-order dependency on AA concentration. When Butylchlorotin dihydroxide was used, the reaction rate revealed the first-order dependency on AA concentration. The activation energy of the reactions catalyzed with p-TSA and Butylchlorotin dihydroxide were calculated at 42.2 and 63.8 kJ/mol, respectively. Addition of 5 wt% Cloisite 30B to the reactant significantly diminished the activity of p-TSA, so the reaction rate decreased and the activation energy was calculated at 72.9 kJ/mol. Butylchlorotin dihydroxide catalyst maintained its activity regardless of the addition of Cloisite 30B to the reactant and the activation energy was calculated to 61.8 kJ/mol. Lewis acid catalyst, butylchlorotin dihydroxide, was more effective than Br${\phi}$nsted acid catalyst for the esterification of AA with DEG.