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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Chemical Society
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Journal DOI :
Korean Chemical Society
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Volume & Issues
Volume 28, Issue 6 - Dec 1984
Volume 28, Issue 5 - Oct 1984
Volume 28, Issue 4 - Aug 1984
Volume 28, Issue 3 - Jun 1984
Volume 28, Issue 2 - Apr 1984
Volume 28, Issue 1 - Feb 1984
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The Crystal and Molecular Structure of Thiosinamine
Shin, Hyun-So ; Koo, Chung-Hoe ; Lee, Soon-Won ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 205~209
The crystal and molecular structure of thiosinamine,
, has been determined by X-ray diffraction method. The crystals are monoclinic, space group
with four molecules in a unit cell of dimensions, a = 9.819(3), b = 8.553(3), c = 9.170(2)
, and z = 4. Intensity data for 814 reflections were collected with a Rigaku-Denki automatic four circle diffractometer. The structure was solved by direct and Fourier methods. Refinements were carried out by full matrix least-squares method to a final R value of 0.046. The thiourea unit is planar, and the bond lengths and angles in that unit agree well with those in the compounds which contain a thiourea moiety. The molecules are linked together by the two patterns of N-H
S hydrogen bonds along the b-axis.
Solvation in Mixed Solvent (III). Solvatochromic Analysis for the Solvent Effect of Binary Mixed Solvent
Lee, Ik-Choon ; La, Sang-Mu ; Lee, Bon-Su ; Sohn, Se-Chul ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 210~216
Solvatochromic comparison methods were applied to determine Taft's solvent parameters,
(solvent hydrogen bond donor acidity) and
(solvent hydrogen bond acceptor basicity) for MeOH-MeCN solvent mixtures. Swain's solvent parameters A(anion solvation scale) and B(cation solvation scale) were also determined by least square fitting of kinetic data in the same binary solvent mixtures. It was found that: (i)
depends on the basicity of the solvent and increases with the MeOH content owing to the increase in polymeric structure of methanol; (ii)
depends on the dipole moment of the solvent and increases with the MeCN content of the solvent; (iii)
increases rapidly with the MeOH content as the hydrogen bond donor acidity of the solvent mixtures increases. Taft's reaction constants a and s and Swain's reaction constants a and b were determined for the reactions reported from our laboratory previously using solvent parameters determined in this work. No meaningful inter-relationship was found between the two set of reaction parameters, but a good linear correlation was found between the ratios a/s and a/b. Solvent effect on the reaction mechanism, substituent effect and leaving group ability were examined in the light of these reaction constants ratios.
Determination of Reactivity by MO Theory (XXXIV). MINDO/3 Theoretical Studies on Sigmatropic Hydrogen Rearrangements (1) : Systems with Central Carbon Atom
Cho, Jeoung-Ki ; Lee, Ik-Choon ; Oh, Hyuck-Keun ; Cho, In-Ho ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 217~230
The MINDO/3 method was used in determination of transition states and activation barriers for various 1,2-, 1,3- and 1,5-sigmatropic hydrogen rearrangements involving systems with central carbon atom. It was found that, besides the consideration of orbital symmetry, steric effect, aromaticity, and orbital interactions were found to dictate the stability of the transition state. For systems with hetero atoms, lone pair orbitals tend to ease orbital distortion required at the transition state by participating in hydrogen transfer process and were found to lower the activation barrier accordingly. Comparison of the relative barrier heights with those obtained by using more sophisticated ab initio MO calculations showed that the MINDO/3 results give qualitatively the same tendency of the relative order of the activation barriers.
Nonstoichiometry of the Yttrium Oxide and the Holmium Oxide
Chang, Soon-Ho ; Yo, Chul-Hyun ; Choi, Jae-Shi ; Pyun, Mu-Sil ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 231~237
The x-values in the nonstoichiometric chemical formulas
, have been measured in the temperature range from 700
C to 1000
C under oxygen pressures from
atm by gravimetric method. The observed x-values increase with increasing temperature and oxygen pressure. The enthalpies of formation of excess oxygen in yttrium oxide and holmium oxide decrease with decreasing oxygen pressure and are all positive values representing an endothermic process. The 1/n values calculated from the slopes of the plots of log x vs. log
increase with temperature and are positive values which means the higher oxygen pressure dependence at higher temperature. We have examined the nonstoichiometric defect and conduction mechanism from x-values and thermodynamic data.
The Molybdate-Sensing Electrodes
Ihn, Gwon-Shik ; Lee, Jung-Hwa ; Min, Tae-Won ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 238~243
electrodes have been prepared and evaluated for sensitivity to molybdate. The 64.5 : 14.0 : 21.5(w/w%) composition is superior in terms of potentiometric response, stability, rapidity of response and reproducibility. Testing was done over the concentration range of
buffer solution at pH 7.95 with constant ionic strength.
, etc. interfere.
Separation and Identification of Polycyclic Aromatic Compounds in Pyrolysis Products of Cellulose and Lignin
Park, Nae-Joung ; Lee, Milton L. ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 244~250
Separation and identification of the polycyclic aromatic compounds (PAC) from pyrolysis products of cellulose and lignin were performed using a combination of acid-base solvent partitioning and silicic acid column chromatography with fused-silica capillary column gas chromatography/ mass spectrometry. Sixteen PAC were positively identifited by retention indices and mass spectra data. Both materials produced the same kinds of PAC. But lignin produced much more PAC than cellulose. Almost no highly carcinogenic heterocyclic PAC containing nitrogen and sulfur were produced.
Surface Photovoltage Spectroscopy on Dyed Zinc Oxide
Kim, Young-Soon ; Sung, Yong-Kiel ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 251~258
The mechanism of photosensitization and the affect of binder on dye-sensitized ZnO have been studied by surface photovoltage spectroscopy. It has been found that the value of energy trapping level
on ZnO is 1.12eV (
= 1,100nm) and that of energy trapping level
on dye-sensitized ZnO is 0.99eV (
= 1,250nm) which is shifted towards a longer wavelength. The effect of binder on ZnO has been increased the efficiency of surface photovoltage, but it does not effect the values of energy trapping level. The acid-type dyes agree well with the prediction based on an electron transfer mechanism. The desensitization of the Na salt-type dyes for the intrinsic photoresponse of zinc oxide can be explained by energy transfer mechanism. It has been obtained that the dye-sensitized ZnO indicates the possibility of electrophotographic photosensitizer for the infrared range of light.
Kinetics and Mechanism of Hydrolysis of Benzenesulfonylimido Phosgene
Sung, Nack-Do ; Han, Sun-Ho ; Kwon, Ki-Sung ; Kim, Tae-Rin ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 259~264
The rate constants for the hydrolysis of benzenesulfonylimido phosgene at various pH were determined by ultraviolet spectrophotometry in 1 : 4 dioxane-water mixed solvents at 25
C and a rate equation which can be applied over a wide pH range was obtained. Based on the Grunwald-Winstein equation, m = 0.4 was obtained. The thermodynamic activation parameters for the hydrolysis were
= 15kcal mol
= 21e.u. at pH 4.0 and
= 8kcal. mol
= -39e.u. at pH 11.0, respectively. It was concluded that the hydrolysis of benzenesulfonylimido phosgene in 1 : 4 dioxane-water mixed solvents proceed via nucleophilic addition-elimination.
Kinetics and Mechanism for Reactions of Substituted Phenacyl Bromides with Quinoline
Kim, Chang-Suk ; Hong, Soon-Yung ;
Journal of the Korean Chemical Society, volume 28, issue 4, 1984, Pages 265~268
Rates of reactions of nine m-or p-substituted phenacyl bromides with quinoline in methanol were measured by an electric conductivity method. These reactions were found to proceed through an
path and were accelerated by both electron-donating and electron-withdrawing substituents. A plausible reaction mechanism for this observation was proposed. Some activation parameters for these reactions were also calculated.