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Complex Formation of Uranium(VI) with Organic Phosphate Ligands in the Solvent Extraction System
도영규,손연수,Do Young Kyu,Sohn Youn Soo Korean Chemical Society 1978 대한화학회지 Vol.22 No.5
우라늄의 수용액 및 산성용액으로부터 추출제 DEPA 및 DPPA로 우라늄을 추출할 때의 메카니즘을 밝히기 위하여 추출 중에 형성되는 우라늄 착물을 분리, 유리한 후 적외선 스펙트럼, 핵자기공명 스펙트럼, 화확분석 및 분자량 측정결과 등을 이용하여 규명하였다. 우라늄은 추출과정에서 유기인산 에스테르인 추출제 DEPA 및 DPPA의 산성 수소와 이온 교환에의하여 킬레이트형의 우라늄 착물을 형성하며 DEPA의 경우 분자량이 약 $2.1{\times}10^4$인 고분자물질임을 알았다. 또한 이러한 유리된 우라늄의 착물은 추출중에 형성되는 착물과 동일함을 밝혔으며 추출제 DEPA의 경우 우라늄의 추출 분배계수는 수용액의 경우 제일 크고 산성 수용액인 경우 $H_3PO_4<H_2SO_4<HClO_4$의 순으로 증가함을 알았다. In order to elucidate the mechanism associated with the solvent extraction of uranium(VI) using DEPA and DPPA as extractant the uranium(VI) complexes formed during the solvent extraction were isolated and characterized by means of IR, NMR, chemical analysis and molecular weight determination. It has been found that uranium(VI) replaces the acidic hydrogen ions of the extractants DEPA and DPPA to form chelated polynuclear complexes, the molecular weight of U(VI)-DEPA complex being $2.1{\times}10^4$. The isolated U(VI)-DEPA complex has been found to be the same chemical species as is formed during the solvent extraction process. In case of DEPA the distribution coefficient of uranium is the largest of the pure aqueous uranium solution and is increasing for the acidic solutions in the order of $H_3PO_4<H_2SO_4<HClO_4$.
Theoretical Prediction of the Thermodynamic Properties of Liquid-Crystalline p-Azoxyanisole
도영규,전무식,이태규,Youngkyu Do,Mu Shik Jhon,Taikyue Ree Korean Chemical Society 1976 대한화학회지 Vol.20 No.2
액체에 대한 significant structure theory 와 상의 전이에 대한 Bragg-Williams근사를 사용하여 액정 화합물인 p-azoxyanisole의 열역학적 성질을 nematic phase와 isotropic phase의 온도범위에 걸쳐 계산하였다. Isotropic phase는 일반적인 액체로 보았으며 nematic phase는 액체적인 성질외에도 분자쌍극자의 배열에 의한 영향도 고려하였다. p-Azoxyanisole의 액체적인 성질은 significant structure theory로 기술하였으며 분자쌍극과 배열에 의한 영향은 Bragg-Williams 근사로써 고려하였다. 부피, 증기압, 정압비열, 열팽창계수, nematic-isotropic 전이점에서의 엔트로피 엔탈피 변화, 절대엔트로피, Helmholtz free energy등을 계산하여 실험치와 비교하였다. The significant structure theory of liquids and the Bragg-Williams approximation of phase transition theory have been applied to the calculation of the thermodynamic properties of p-azoxyanisole which exhibits a liquid crystal phase of the nematic type. The isotropic phase was treated as a normal liquid; and for the nematic phase, in addition to its liquidity, the effect due to the arrangement of molecular-dipoles was considered. The liquidity of the p-azoxyanisole was described by the significant structure theory of liquids, and the Bragg-Williams approximation was used to consider the effect due to the arrangement of molecular-dipoles. The molar volume, vapor pressure, heat capacity at constant pressure, thermal expansion coefficient, compressibility, entropy and enthalpy change at the nematic-isotropic phase transition point, absolute entropy, and absolute Helmholtz free energy were calculated over the temperature range of the nematic and isotropic phases. The calculated results of the thermodynamic properties were compared with the experimental data.
Mechanistic Study of Half-titanocene-based Reductive Pinacol Coupling Reaction
김영조,도영규,박성진 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.11
The reductive pinacol coupling reaction of aldehydes or ketones creating a new C-C bond has been a major tool to produce 1,2-diol compounds. The reaction mechanism is known to be composed of sequential three steps (activation, coupling, and dissociation). In this work, we studied the dissociation step of half-titanocene-based catalytic systems. Cp and Cp* derivatives of the pinacolato-bridged dinuclear complex were synthesized and evaluated as possible models for intermediates from the coupling step. We monitored ^1H-NMR spectra of the reaction between the metalla-pinacol intermediates and D_2O. New reaction routes of the dissociation step including oxo- and pinacolato-dibridged dinuclear complexes and oxo-bridged multinuclear complexes have been suggested.
김진권,도영규,Jin Mook Lim 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.7
[Mn12O12(O2CPh-4-SMe)16(H2O)4]•7CH2Cl2 (1), a new single-molecule magnet complex has been successfully synthesized by substitution of acetate ligand of Mn12ac with 4-(methylthio)benzoic acid. Complex 1 crystallizes into triclinic P with a = 18.321(3) Å, b = 19.011(3) Å, c = 27.230(4) Å, = 86.973(3)o, = 76.919(3)o, = 87.613(3)o, and Z = 2. In complex 1, one Mn(III) ion has an abnormal Jahn-Teller elongation axis oriented at an oxide ion. Complex 1 has two out-of-phase ac susceptibility peaks in the 2-4 K and 4-7 K regions. Effective anisotropy energy barrier and pre-exponential factor are Ueff = 45.95 K, 1/0 = 8.6 ´ 109 s1 for M'' peaks in the lower temperature region and Ueff = 59.45 K, 1/0 = 2.2 ´ 108 s1 for M'' peaks in the higher temperature region. The parameters of S = 10, g = 1.87, D = 0.40 cm1, and E = 0.00034 cm1 were obtained from the M/NB vs. H/T plot of complex 1.