• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.280-286
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• 1987

The effect of substituent inleaving group on the rates of reactions of phenacyl substituted-benzenesulfonates with pyridine was determined conductometrically in acetonitrile and in methanol at 35, 45, and $55^{\circ}C$, respectively. The reaction rate became faster in proportion to electron-attracting ability of substituent, which indicates that the substituent in leaving group can directly control reaction rate. It was shown that the specific to the carbonyl carbon as the rate-determining step.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.31-38
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• 2019

In this study, amine derivatives and ion exchange resins were selected to actively control penetration ions ($SO{_4}^{2-}$, $Cl^-$) as the element technology of repair materials for concrete structures in drainage environments. Ions ($SO{_4}^{2-}$, $Cl^-$) adsorption performance and corrosion resistance of calcium hydroxide solution with amine derivative and ion exchange resin were confirmed by ion chromatography and potentiostat analysis. As a result of the experiment, it was confirmed that the amine derivative is excellent in the adsorption of chlorine ion and the ion exchange resin is excellent in the adsorption of sulfate ion. It has been confirmed that corrosion resistance can be increased by proper combination of two materials in the calcium hydroxide solution containing sulfate ion and chloride ion simulating sewage environment.

• Polymer(Korea)
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• v.27 no.3
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• pp.242-248
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• 2003

PP-g-(AN/Sty) was synthesized by grafting with acrylonitrile (AN) and styrene (Sty) onto PP staple fiber using an electron beam accelerator and followed by amidoximination and phosphorylation. Mole fraction of AN in the graft chain increased with the increase of the AN content in the monomer mixture. The highest AN grafting yield of 45% was obtained at a monomer ratio of 40 vol% AN/60 vol% Sty. Mole fraction of AN in the graft chain decreased with the increase of methanol amount used its solvent. As reaction temperature increased, the grafting yield of copolymer increased and reached equilibrium at 50$^{\circ}C$. Amount of amidoxime group in fibrous ion exchanger was increased as increasing amount of hydroxylamine, and the maximum content of amidoxime group was observed at 5.8 mmol/g with the 9 wt% hydroxylamine concentration. Content of phosphorous group in fibrous ion exchanger increased up to 0.5 N phosphoric acid concentration, and then leveled off. The adsorption ability of the copolymer for uranyl ion by the chelating adsorbents was in the following order : bifunctional PP-g-(AN/sty) > amidoximated PP-g-(AN/Sty) > phosphorylated PP-g-(AN/Sty).

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.407-413
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• 2022

This study demonstrates a method for synthesis of amine functionalized and easily size controllable silica nanoparticles through biomimetic polyamine complex. First, we generate a polyamine nanocomplex composed of polyallylamine hydrochloride (PAH) and phosphate ion (pi) to synthesize silica nanoparticles. The size of polyamine nanocomplex is reversibly adjusted within the range of about 50 to 300 nm according to the pH conditions. Amine groups of the PAH in the nanocomplex catalyzes the condensation reaction of silicic acid. As a results, silica nanoparticles are synthesized based on nanocomplex in a very short time. Finally, we synthesize silica nanoparticles with various sizes according to the pH conditions. In the process of synthesizing silica nanoparticles, polyamine chains that act as catalysts are incorporated into the inside and surface of the particles, subsequently, amine groups are exposed on the surface of silica nanoparticles. As a results, the synthesis and surface modification of silica nanoparticles are performed simultaneously, and the silica nanoparticles introduced with amine groups can be easily synthesized by adjusting the sizes of the silica nanoparticles. Finally, we demonstrate the synthesis of functional silica nanoparticles in a short time under milder conditions than the conventional synthetic method. Furthermore, this method can be applicable to bioengineering and materials fields.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.914-919
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• 1998

Optically pure $C_2-Symmetric$ pyrrolidine amides (8) were synthesized from readily available 1,2:5,6-di-O-isopropylidene-D-mannitol (1). Cyclization of dimesylated hexitol (4) with benzyl amine gave an inseparable mixture of $C_2-Symmetric$ pyrrolidine amine derivative (5) as a major product, concurring with its cis isomer (6) as a minor product. The pyrrolidine amines (5,6) were converted to separable pyrrolidine amides (8,9) via free amine (7). Optical purity of desired $C_2-Symmetric$ pyrrolidine amide (8a) was determined with its Mosher derivatives (13,14) by their $^1H$ and $^{19}F$ NMR spectra.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.716-726
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• 2013

Enzymatic acylations catalyzed by hydrolytic enzymes, along with enzymatic hydrolysis, are established reactions in the synthesis of fine chemicals such as chiral intermediates and polymerizations in the industry. Those reactions have been carried out mostly in organic media due to the thermodynamic limitations. Recently, there have been reports on enzymatic acylations in aqueous media. They have dealt with the elucidation of reaction mechanisms of hydrolases and acyl transferases based on their X-ray structures, homology comparison of the two kinds of enzymes, substrate engineering of acyl donors and computational design of acyl transferases for enzymatic acylations in aqueous media. Enzymatic acylations play an important role in the combinatorial synthesis of natural products such as polyketides and nonribosomal peptides. In this review, the historic developments of enzymatic acylations and industrial examples are described briefly. In addition, recent developments of enzymatic acylations in the modification of natural products and their prospects will be discussed.

• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.177-182
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• 2006

In this work, we have prepared organophilic MMT having thermal stability by ion exchange reaction of various aromatic ammonium salts with MMT containing sodium ion. The organic modifiers having alkyl side chains and amine functional group were successfully synthesized by effectively introducing the surfaces of MMT via ion exchange reaction to form organophilic MMTs with a view to improve the reactivity and thermal stability. The WAXD patterns of organophilic MMT showed the more increased gallery spacing by $3.3{\AA}$ than that of the pristine MMT and also the onset of initial decomposition of organophilic MMT was $275^{\circ}C$ as determined by a thermogravimetric analysis. The polyimide (PI) nanocomposite films based on poly(amic acid) and organophilic MMT were prepared by a solution blending followed by cyclodehydration reaction. We have investigated the dispersity of organophilic MMTs in PI matrix by using WAXD and the effect of the organophilic MMT content on the mechanical properties of PI nanocomposite films was studied.

• Membrane Journal
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• v.27 no.4
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• pp.336-343
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• 2017

These days, the quality of indoor air is a very important concept for modern people who have lived in building and is a matter of new thinking. The quality is determined by the temperature and humidity of indoor air. In addition, there is a disadvantage in that energy consumption is severe for indoor air improvement. Therefore, researches on methods to solve such problems using total heat exchange have been actively conducted. So, in this study, aminated poly(styrene-ethylene-butylene-styrene) polymers were synthesized by introducing a hydrophilic substituent, ammonium, into main chain and the properties of synthesized polymers were evaluated. The synthesis was carried out through chloromethylation and amination reactions to introduce ammonium into main chain. As a result, the water uptake and the ion exchange capacity of the synthesized polymers increased as the content of the reaction reagent solution increased. It was confirmed that the important data at the total heat exchange membrane, water vapor transmission rate also increased according to temperature, equivalent.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.714-722
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• 2019

Catalysts were prepared by using incipient wetness impregnation method with 17 wt% Ni on a support ($SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, $SiO_2$, $TiO_2$, MgO) and the catalytic activity in the reductive amination of ethanol with ammonia in the presence of hydrogen was compared and evaluated. The catalysts used before and after the reaction were characterized using X-ray diffraction, nitrogen adsorption, ethanol-temperature programmed desorption (EtOH-TPD), isopropanol-temperature programmed desorption (IPA-TPD), and hydrogen chemisorption etc. In the case of preparing $ZrO_2$ and $Y_2O_3$ supports, the small amount of Si dissolution from the Pyrex reactor surface provoked the formation of mixed oxides $SiO_2-ZrO_2$ and $SiO_2-Y_2O_3$. Among the catalysts used, $Ni/SiO_2-Y_2O_3$ catalyst showed the best activity, and this good activity was closely related to the highest nickel dispersion, and low desorption temperature in EtOH-TPD and IPA-TPD. The low catalytic activity on Ni/MgO catalysts showed low activity due to the formation of NiO-MgO solid-solutions. In the case of $Ni/TiO_2$, the reactivity was low due to the low nickel metal phase due to strong metal-support interaction. In the case of using a support as $SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, and $SiO_2$, the selectivities of ethylamines and acetonitrile were not significantly different at similar ethanol conversion.

• KSBB Journal
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• v.19 no.3
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• pp.215-220
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• 2004

A variety of solid bases such as inorganic bases, basic anion exchange resins, and resin-bound bases were tested as a catalyst for racemization of (S)-naproxen 2,2,2-trifluoroethyl thioester in isooctane at 45$^{\circ}C$. Among the various bases, DIAIOM WA30, which is a weakly basic anion exchange resin with a tertiary amine based on a highly porous type styrene-divinylbenzene copolymer, showed the highest catalytic activity. The second-order interconversion constant of DIAION WA30 was 8.6${\times}$10$\^$-4/ mM$\^$-1/h$\^$-1/ and about 3 times higher than that of trioctylamine under the same conditions. The rate of DIAION WA30-catalyzed racemization decreased with increasing an amount of water added to the reaction medium. Lipase-catalyzed kinetic resolution of racemic naproxen 2,2,2-trifluoroethyl thioester was successfully carried out under in situ racemization of substrate with DIAION WA30 in isooctane at 45$^{\circ}C$. More than 60% conversion and 99% enantiomeric excess for the desired (S)-naproxen product were obtained. Furthermore, such a solid base catalyst could be easily separated and reused in contrast to trioctylamine.