• Polymer(Korea)
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• v.25 no.5
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• pp.642-648
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• 2001

An attempt was made to synthesize an ammonia adsorbent by the photo-induced grafting of styrene (St) onto polypropylene (PP) nonwoven using benzoin ethyl ether (BEE) as a photosensitizer with urea and trimethylol propane triacrylate in methanol medium. As styrene concentration was increased, the graft yield was increased. It was also found that the graft yield increased with reaction time. The polypropylene grafted with styrene (PP-g-St) was sulfonated by chlorosulfonic acid in dichloroethane and complexed with several metal ion, such as $cO^{+2}$, $nI^{+2}$, $cU^{+2}$, $Zn^{+2}$. The amount of ammonia gas adsorbed by these sample was dependent on the degree of sulfonation, adsorption time, and ammonia gas pressure. The adsorption capacity of ammonia gas by the sulfonated PP-g-St(SPP-g-St) nonwoven with 4. 25 mmol $H^+$/g was 6.61 mmol/g. Metal ion complexed SPP-g-St nonwovens had higher adsorption capacity than SPP-g-St nonwoven and the $Co^{+2}$ complexed SPP-g-St showed 9.90 mmol $NH_3$/g, which was much higher than that of active carbon or silica gel.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.648-653
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• 2014

Cr(VI)-heterocyclic complex (2,4'-bipyridinium chlorochromate) was synthesized by the reaction between heterocyclic compound(2,4'-bipyridine) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,4'-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase of the dielectric constant (${\varepsilon}$), in the order : N,N-dimet-hylformamide (DMF) > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as hydrochloric acid (HCl solution), 2,4'-bipyridinium chlorochromate oxidized benzyl alcohol (H) and its derivatives (p-$CH_3$, m-Br, m-$NO_2$). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.67 (303 K). The observed experimental data have been rationalize the proton transfer occurred followed the formation of a chromate ester in the rate-determining step.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.53-59
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• 1988

Recently, the formation of the complexes between macrocyclic polyethers and alkali metal salts have been determined by several methods. It has been suggested that the specificity of the complexation be due to the nature of the surrounding solvent molecules. The formation constant values ($K_f$) of $K^+$ are shown to be the largest among the other alkali metal cations because the ionic diameter of $K^+$ is approximately the same with the hole size of 18-crown-6. In this study the formation constants of the 1 : 1 complexes of 18-crown-6 with potassium p-substituted phenoxide are calculated by the conductance measurement in organic solvents. As a result, the $K_f$ value series among organic solvents are given in the order of $CH_3$OH > DMF > DMSO. It seems that the donor number of the solvent is a main factor in the formation of the complex between $K^+$ metal ion and 18-crown-6 molecules. At the same time, the formation constants increase with increasing the electron-withdrawing power of substituents because the phenoxide ion is stabilized by the charge dispersion.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.61-66
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• 1981

A method for calculation of the contribution of $\pi$ bonding molecular orbitals to the dipole moments for octahedral [M(III)$A_3B_3$] type complexes has been developed [M(III) = Ti(III), V(III), Cr(III), Fe(III) or Co(III); A = O or N; B = N, S or Cl]. The contribution of ${\pi}$ bonding molecular orbitals to the dipole moments is found to be smaller than that of ${\sigma}$ bonding molecular orbitals but this contribution may not be negligible even for chelate complexes in which delocalization of ${\pi}$ electron is assumed. The calculated dipole moments (u = $u_{\sigma}$ + $u_{\pi}$) are closer to the experimental values than those for the case where only ${\sigma}$ bonds are assumed to be formed.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.509-515
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• 1994

The interactions of 11 kinds of primary and secondary alkylammonium ions with cyclic (12C4, 15C5, 18C6, DT18C6 and DA18C6) and acyclic$(Q_2O_5)$ polyethers were investigated by NMR titration and conductometry. All of the alkylammonium ions under investigation form the relatively stable 1 : 1 complexes with crown ethers and acyclic polyether by H-bond. The interactions of alkylammonium ions with analogeous hosts having different size were in the order of 18C6 > 15C5 > 12C4, and the strengthes of donor atoms toward the alkylammonium ions were in the order of N > O > S. 18C6 forms more favorable interactions with primary alkylammonium ions than secondary alkylammonium ions, otherwise DA18C6 shows the opposite behaviors. The stability constants for complexations of 18C6 with the alkylammonium ions were determined conductometrically in methanol at 25$^{\circ}C$. The major factors affecting the stability of complexes were the type of alkylammonium ions, the length of alkyl-chain and the steric hindrance due to the structure of alkyl groups on complexation.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.28-36
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• 1996

The pentanuclear complexes have been obtained by the reactions of molybdenum(VI) and tungsten(VI) polynuclear complexes with molybdenum(O) and tungsten(O) dinitrosyl mononuclear complexes, and methylthioamidoxime. The prepared complexes (n-Bu4N)2[Mo4O12Mo(NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2](1), (n-Bu4N)2[W4O12Mo(NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2](2), (n-Bu4N)2[Mo4O12W (NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2] (3) have been characterized by elemental analysis, infrared, UV-visible and 1H NMR spectra. The complexes are elucidated the cis-{M(NO)2}2+(M = Mo, W) unit and a slight delocalization by spectroscopy. The structure of (n-Bu4N)2[W4O12Mo(NO) 2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2] was determined by X-ray single crystal diffraction. Crystal data are follows: Monoclinic, $P21}a$, a = 22.14(2) $\AA$, b = 14.93(1) $\AA$, c = 23.20(1) $\AA$, $\beta$ = 111.08(6) $\AA$, V = 7155(9) $\AA$, Z = 4, final R = 0.072 for 6191(I > $3\sigma(I)).$ The structure of complex forms two dinuclear [W2O5{CH3SCH2C(NH2)NHO}{CH3SCH2C(NH)NO}] and a central {Mo(NO)2} 2+ core. The geometric structure of the {Mo(NO)2} 2+unit is the formally cistype and C2v symmetry.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.1-5
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• 2010

Cu(II)-organic complexes were synthesized with Lewis base organic ligands including diamine, aminothiol, and dithiol to determine the reactivity for DFP hydrolysis. Results show that the aminothiol catalyst enhances the hydrolysis of DFP in three folds compared to diamine type because aminothiol has higher basicity than diamine. Due to low solubility of Cu(II)(1,2-ethane dithiol)$(NO_3)_2$, it is impossible to compare directly the rates in homogeneous condition. However, the rate of dithol complex is even 1.6 times faster than that of the diamine type. The reactivity of zeolite for DFP hydrolysis is also evaluated. NaY type does not promote the hydrolysis, but RuNaY shows relatively lower reactivity than those of Cu(II)-organic ligands complexes.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.729-734
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• 2008

The higher valence state of iron i.e., Fe(VI) was employed for the treatment of Cu(II)-EDTA in the aqueous/waste waters. The ferrate(VI) was prepared through wet oxidation of Fe(III) by sodium hypochlorite. The purity of prepared Fe(VI) was above 93%. The stability of Fe(VI) solution decreased as solution pH decreased through self decomposition. The reduction of Fe(VI) was obtained by using the UV-Visible measurements. The dissociation of Cu(II)-EDTA complex through oxidation of EDTA using Fe(VI) and subsequent treatment of organic matter and metal ions by Fe(III) reduced from Fe(VI) in bench-scale of continuous flow reactor were studied. The removal efficiencies of copper were 69% and 79% in pH control basin and reactor, respectively, at 120 minutes as retention time. In addition, Cu(II)-EDTA in the reactor was decomplexated more than 80% after 120 minutes as retention time. From this work, a continuous treatment process for the wastewater containing metal and EDTA by employing Fe(VI) as muluti-functional agent was developed.

• Nuclear Engineering and Technology
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• v.27 no.1
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• pp.18-24
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• 1995

Characteristics of poly(vinyl alcohol)-poly(methacrylic acid) system (PVA.-PMAA system) for fixation of radioactive contaminant on sand were studied. Dissociation of carboxyl group in PMAA was found to be suppressed by PVA Permeability of sand layer treated with PVA-PMAA solution is directly proportional to the PMAA concentration when the ［PMAA］ is below 0.082 M and the empirical proportional constant (k) is -8.95$\times$10￣$^4$cm$^{5}$ /mole. The change of permeability can be explained by the formation of an intermacromolecular complex between PVA and PMAA The polymer bridge formed on a sand surface combines sand yams more firmly. The PVA-PMAA system is more effective than the PVA system for the fixation of deposited condensational radionuclides.

• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.445-452
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• 1996

Catalytic hydrogenation of ketones and aldehydes by RuH(NO)$L_3$ ($L_3$: $PPh_3$, PhP($CH_2CH_2PPh_2$)$_2$(etp)) was investigated to examine the reaction mechanism and the competence of hydridonitrosyl complexes as catalysts for organic synthesis. RuH(NO)$L_3$ showed catalytic activity for the hydrogenation and the activities of catalysts were dependent on the steric and electronic factors. The less the steric demands of the substrates become, the more activity the catalysts show. For the electronic effect, the more the partial positive charge on the carbonyl carbon atom in ketones becomes and the more the double bond character of carbonyl group in aldehydes becomes, the more active the catalysts are. These results reflect the difference of reaction mechanisms of two substrates, ketones and aldehydes. Catalytic activities of RuH(NO)(etp) and RuH(NO)($PPh_3$)$_3$ in the presence of extra $PPh_3$ toward hydrogenation showed the existence of a reaction pathway accompanied with the change of the bonding modes of NO ligand. The roles of excess $PPh_3$ change with increase of the mole ratio of $PPh_3$ to catalysts; prevention of ligand dissociation from comlexes → bases → ligands. The activity of RuH(NO)(etp) was lower than that of RuH(NO)($PPh_3$)$_3$ toward the hydrogenation of the same substrates mainly due to the structural difference. These catalysts showed the selectivity toward olefin hydrogenation over carbonyl groups in the competitive reaction.