• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.527-533
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• 1991

Template condensation reactions of formaldehyde with appropriate tetramines and diamines in the presence of N(II) or Cu(II) ion produce square planar complexes of hexaaza macrotricyclic and macrotetracyclic ligands $[M(L)]^{2+}$(M = Ni(II) or Cu(II); L = 4-methyl-1,3,6,8,11,14-hexaazatricyclo[12,2,1,$1^{8,11}$]octadecane(C), 1,3,10,12,15,18-hexaazatetracyclo[16,2,1,$1^{12,15},0^{4,9}]$docosane(D) 4-methyl-1,3,6,8,12,15-hexaazatricyclo[13,3,1,$1^{8,12}$]eicosane(F), or 1,3,10,12,16,19-hexaazatetracyclo[l7,3,1,$1^{12,16},0^{4,9}]$tetracosane(G). These complexes contain two 1,3-diazacyclopentane or 1,3-diazacyclohexane rings in the six-membered chelate rings. The complexes of C and F contain one methyl group and those of D and G one cyclohexane ring in the five-membered chelate ring. Synthesis and characterization of the Ni(II) and Cu(II) complexes are presented. The effects of the ligand structure on the equilibrium $[Ni(L)]^{2+}2H_2O{\rightleftharpoons}[Ni(L)(H_2O)_2]^{2+}$ in aqueous solutions are described.

• Polymer(Korea)
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• v.36 no.2
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• pp.223-228
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• 2012

Temperature and pH sensitive graft copolymers [Pluronic-$g$-poly(NIPAAm-$co$-MMA), Polymer A] and [Pluronic-$g$-poly( NIPAAm-$co$-MAA), Polymer C] were synthesized by macro radical graft polymerization with $N$-isopropylacrylamide (NIPAAM)/$N,N$-diethylaminoethylmethacrylate (DEAEMA) and $N$-isopropylacrylamide (NIPAAm)/methacrylic acid (MAA) based on Pluronic, respectively. The chemical structure and molecular weight of the graft copolymers was characterized by $^1H$ NMR and gel permeation chromatography. The aqueous solution properties of graft copolymers were measured using a UV-visible spectrophotometer, contact angle and dynamic light scattering equipment with different temperature and pH conditions. The obtained graft copolymers showed a very sensitive phase transition in response to temperature and pH in aqueous media which suggested that the amine group of DEAEMA segment and carboxylic group of MAA had a great influence on the lower critical solution temperatures (LCST) in Polymer A and C, respectively. The graft copolymers can be utilized for drug delivery system and molecular switching applications where responses to temperature and pH changes are relevant.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.555-560
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• 2023

Conventional aqueous amine-based CO₂ capture has a problem in that a large amount of renewable energy is required for CO₂ stripping and solvent regeneration in its industrial applications. This work proposes a water-lean absorbent that can reduce regeneration energy by lowering the water content in the absorbent with high absorption capacity for CO₂. To this purpose, this water-lean solvent introduced NMP (N-methyl-2-pyrrolidone), which has a higher physical solubility in CO₂ and a low specific heat capacity comparing to water, along with 3-methylaminopropylamine (MAPA), a diamine, into the absorbent. The circulating absorption capacity and absorption rate for CO₂ of this water-lean solvent were measured using a packed tower. When NMP was added to the absorbent, the absorption rate was improved. In the case of the absorbent containing 2.5M MAPA was used, the maximum circulating absorption capacity was obtained when 10 wt% of NMP was included in absorbent. The overall mass transfer coefficient increased as the concentration of NMP increased. However, at loading values higher than 0.5, the increment in mass transfer coefficient decreased as the concentration of NMP increased. When the lean loading value is low, the mass transfer resistance due to viscosity of the absorbent is low, so the overall mass transfer coefficient increases with the addition of NMP. However, as the lean loading value increases, the viscosity of the absorbent increases, and the diffusivity of CO₂ and MAPA decreases, resulting in sharply decreasing of the overall mass transfer coefficient.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.330-337
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• 2011

In this research, the preparation processes for making a series of $\omega$-mercapto alkylamine 1 and $\omega$-mercapto alkanoic acid 2 useful for studying of the self-assembled monolayer(SAM) are described. The preparation methods of the first goal materials, $\omega$-mercapto alkylamines 1 were carried out as follows: First, $\omega$-phthalimide alkanol 3 was synthesized from commercially available potassium phthalimide derivatives and $\omega$-bromoalkanol in DMF at $80{^{\circ}C}$ via substitution reaction. After refluxing $\omega$-phthalimide alkanol 3 with hydrazine hydrate in ethanol followed by treating with c-HCl, $\omega$-aminoalkanol 4 was obtained in 76-98% yield, accompanied with side-product 5. Bromination of hydroxyl moiety of $\omega$-aminoalkanol 4 using aqueous hydrobromic acid furnished $\omega$-bromoamine 6 in 34-97% yields. Substitution reaction 6 with thiourea in 95% ethanol gave $\omega$-aminoalkanthiuronium 7, which was treated with aqueous strong base and aqueous strong sulfuric acid gave desired products, $\omega$-mercapto alkylamines 1 through overall 5 steps. The second target material, $\omega$-mercapto alkanoic acid 2 was prepared via 2 steps. $\omega$-bromo alkanoic acid was reacted with thiourea to give $\omega$-thiourea alkanoic acid 7 in 69-85%, which was treated with aqueous strong base and strong acid to furnish $\omega$-mercapto alkanoic acid 2 in 50-98%. The fabricated long-chain alkylthiol(LCAT) can be used as linkers to immobilize protein, enzyme and various kinds of biomolecules on the surface of metallic materials(Au, Pt, Ti) by SAM, and can be useful chemical tools for the application study on the surface modification of metallic materials.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.485-494
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• 2000

According to the worldwide interest in controlling $CO_2$ which contributes to green house effect. new techniques of reducing $CO_2$ are under development. We have developed new technique for reducing $CO_2$. In low $CO_2$ concentration. the chemical absorption method is useful. In this study. the kinetics of the reaction between $CO_2$ and the sterically hindered amine solution with piperazine. have been investigated from measurements of the rate of absorption of $CO_2$ in the stirred vessel that has a horizontal liquid-gas interface, in the temperature range $30{\sim}70^{\circ}C$. The experiments were carried out in the range 10.130~20.260 kPa of partial pressure of $CO_2$, and in aqueous $2.0kmol/m^3$ AMP solution with $0{\sim}0.4kmol/m^3$ piperazine The experimental results are as follows: 1) The absorption rate of $CO_2$ into aqueous AMP + piperazine solution is gett ng faster than that of aqueous AMP absorbents with temperature. Because the activation energy of piperazine 57.147 kJ/mol is higher than that of AMP 41.7kJ/mol. therefore the effect of piperazine on absorption rate increases with temperature. 2) Compared with aqueous AMP solution. the absorption rate of $CO_2$ into AMP + piperazine solution increases from 6.33% at $30^{\circ}C$ to 12% at $70^{\circ}C$, so AMP + piperazine solution is thought to be a better than AMP solution, 3) The reaction rate constants of piprazine in aqueous AMP solution with $CO_2$ have been determined as 217.21, 420.46, 707.00 and $3162.167m^3/kmol{\cdot}s$ respectively at 30, 40, 50 and $70^{\circ}C$ but these results are higher than those of Xu which were 186.7. 367.32. 693.01. $2207.65m^3/kmol{\cdot}s$ at 30, 40, 55, $70^{\circ}C$in aqueous MDEA solution. So the regression analysis of the data has led to the following equation In $k_p$ =28.324-6934.7/T.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.94-102
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• 1981

To investigate the characteristics of anodic film formed on metals and the reactivities of organic inhibitor Di-iso-butylnitrosoamine (DBNA) in sea water. the cathodic reactions of anodic film formed on metals were carried out by using the potential drop method and galvanostatic method at $25^{\circ}C$. The investigated results are as follows: The anodic films formed on aluminum and zinc in 60mM $DBNA+9\%_{\circ}$ sea water did not show-changes of potential drop. However, those formed on lead and copper were reasonable electrodes. It was concluded that cathodic reactivities of proton through the anodic film in aqueous solution were constant without regard to the kinds of metals used with anodic film electrode at operated current density ranges, because the values of transition time obtained in 0.5M sodium chloride solution and $9\%_{\circ}$ sea water nearly coincided. The values of transition time of the first step by the galvanostatic method were obtained from 0.22 to 1.40 sec ranges far less than one minute. Therefore, it suggested that cathodic reactions of proton through the anodic film were mainly controlled by diffusion/adsorption process. The differences of between $\tau_{1}/4$ in $9\%_{\circ}$ sea water and $\tau_{1}/4$ in 60mM $DBNA+9\%_{\circ}$ sea water, and between $E_{1}/4$ in sea water and $E_{1}/4$ in 60mM $DBNA+9\%_{\circ}$ sea water at the constant current density with $1.9\times10^{-4}\sim5.0{\times}10^{-6}\;amp/cm^2$ were 0.06 sec and 0.53 v. respectively and cathodic reactions of DBNA on the anodic film electrodes were chiefly controlled by adsorption/diffusion process. The reason that adsorption quantities of proton on anodic film formed on aluminum and zinc in aqueous solutions were much more than those on lead and copper, seems to lie due mostly to the number of porosity produced on anodic film used.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.565-578
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• 1992

It has been suggested that Hg$^{2+}$-promoted reaction of a series of cis-[Co(en)$_2$(L)Cl]$^{2+}$ (en = 1,2-diaminoethane) with L = NH$_3$, NH$_2$CH$_3$, glyOC$_2$H$_5$, glyOCH$_3$, dl-alaOC$_2$H$_5$, NH$_2$CH$_2$CONH$_2$, and NH$_2$CH$_2$CN proceeds by dissociative interchange(I$_d$) mechanism from kinetic data, circular dichroism spectra, analyses of products, and the values of m(Grunwald-Winstein plot) using Y (solvent ionizing power) in aqueous solution and in mixed aqueous-organic solvent. It has been found that chloride replacement by water (aquation) for the series with L = NH$_3$ and NH$_2$CH$_3$ and chelation of ligand L to Co(Ⅲ) for the series with L = glyOC$_2$H$_5$, glyOCH$_3$, dl-alaOC$_2$H$_5$, NH$_2$CH$_2$CONH$_2$, and NH$_2$CH$_2$CN occurs, respectively. The rate constants on Hg$^{2+}$-induced reaction of the series except cis-[Co(en)$_2$(NH$_2$CH$_2$CN)Cl]$^{2+}$ were increased with increasing the contents of ethanol in mixed water-ethanol solvents. In mixed water-30${\%}$ organic solvents, the rate constants of the series except cis-[Co(en)$_2$(NH$_2$CH$_2$CN)Cl]$^{2+}$ have also been measured in the order 30${\%}$ 2-propanol-water > 30${\%}$ ethanol-water > water. However, the rate constants of cis-[Co(en)$_2$(NH$_2$CH$_2$CN)Cl]$^{2+}$ were reversed. The rate constants of the series with L= NH$_3$ and NH$_2$CH$_3$ were related to ligand field parameter (${\Delta}$), but those of the series with L = glyOC$_2$H$_5$, glyOCH$_3$, dl-alaOC$_2$H$_5$, NH$_2$CH$_2$CONH$_2$, NH$_2$CH$_2$CN were not. The reaction between the series and Hg2+ in aqueous media containing NO$_3^-$ has been investigated. The results for the reaction do not alter the mechanism, but the rate only was altered.