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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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Korean Chemical Society
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Volume & Issues
Volume 51, Issue 6 - Dec 2007
Volume 51, Issue 5 - Oct 2007
Volume 51, Issue 4 - Aug 2007
Volume 51, Issue 3 - Jun 2007
Volume 51, Issue 2 - Apr 2007
Volume 51, Issue 1 - Feb 2007
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Corrosion and Passivation of Copper in Artificial Sea Water
Chon, Jung-Kyoon ; Kim, Youn-Kyoo ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 305~311
DOI : 10.5012/jkcs.2007.51.4.305
Based on the cyclic voltammograms, potentiodynamic polarizations, transient and steady state Tafel plots and electrochemical impedence spectroscopy, we proposed the copper redox mechanism of the corrosion and passivation in artificial sea water. The copper redox mechanism showed the dependence of the concentration of oxygen in artificial sea water and electrode potentials.
Study of Excess Gibbs Energy for a Lattice Solution by Random Number Simulation
Jung, Hae-Young ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 312~317
DOI : 10.5012/jkcs.2007.51.4.312
Performing random number simulations, we approximated that the distribution of the number of ways for arranging molecules randomly on a lattice is a normal distributon for N12, the number of interactions between the nearest neighbors of different molecules. From this distribution, an approximate equation of the excess Gibbs energy GE for a lattice solution of nonrandom mixing was derived. Using the equation, liquid-vapor equilibria of several binary solutions were calculated and compared with the calculated result of other equations.
Electronic Spectroscopy of Protonated Tyr-Ala Dipeptide Ions
Choi, Chang-Min ; Kwon, Jang-Sook ; Kim, Hwan-Jin ; Yoon, Tae-Oh ; Yang, Min-O ; Kim, Nam-Joon ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 318~323
DOI : 10.5012/jkcs.2007.51.4.318
Electronic photofragmentation spectrum of protonated tyrosine-alanine dipeptide ions(YAH+) was obtained in the wavenumber region of 34500~36700 cm-1 using a quadrupole ion trap time-of-flight mass spectrometer (QIT-TOFMS). YAH+ ions were produced by electrospray ionization, stored in the ion trap and then irradiated by ultraviolet laser pulses which induced photofragmentation of the ions. The electronic photofragmentation spectrum was obtained by monitoring the photodissociation yields of YAH+ ions as a function of the laser wavelength. The spectrum exhibited two broad peaks which were assigned as S1 and S2 by theoretical calculations using a time-dependent density functional method. The broad widths of the peaks in the spectrum were explained by the overlaps of the peaks originated from various conformers of YAH+ ions which were present in the gas phase at room temperature and also by the contributions of the hot bands.
A Highly Selective Mercury(II) Ion-Selective Membrane Sensor
Ensafi, Ali A. ; Meghdadi, S. ; Allafchian, Ali R. ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 324~330
DOI : 10.5012/jkcs.2007.51.4.324
A new ion selective PVC membrane electrode is developed as a sensor for mercury(II) ions based on bis(benzoylacetone) propylenediimine (H2(BA)2PD) as an ionophore. The electrode shows good response characteristics and displays, a linear Emf vs. log[Hg2+] response over the concentration range of 1.0×10-6 to 1.0×10-1 M Hg(II) with a Nernstian slope of 29.8±0.75 mV per decade and with a detection limit of 2.2×10-7 M Hg(II) over the pH range of 2.5-11.5. Selectivity concentrations for Hg(II) relative to a number of potential interfering ions were also investigated. The sensor is highly selective for Hg(II) ions over a large number of cations with different charge. The sensor has been found to be chemically inert showing a fast response time of 60 s and was used over a period of 3 months with a good reproducibility (S = 0.27 mV). The electrode was successfully applied to determine mercury(II) in real samples with satisfactory results.
Direct and Derivative Spectrophotometric Determination of Cobalt (II) in Microgram Quantities with 2-Hydroxy-3-methoxy Benzaldehyde Thiosemicarbazone
Kumar, A.Praveen ; Reddy, P.Raveendra ; Reddy, V.Krishna ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 331~338
DOI : 10.5012/jkcs.2007.51.4.331
A rapid, simple and sensitive spectrophotometric method was developed for the determination of cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a analytical reagent. The metal ion in aqueous medium forms a brown coloured complex with HMBATSC at pH 6.0. The complex has two absorption maxima at 375 nm and 390 nm. At 375 nm, the reagent shows considerable absorbance, while at 390 nm the reagent does not shows appreciable absorbance. Hence, analytical studies were carried out at 390 nm. Beer's law is obeyed in the range of 0.059-2.357 μg ml-1 of Co(II). The molar absorptivity and Sandall's sensitivity of the method are 2.74×104 l mol-1 cm-1 and 0.0024 μg cm-2 respectively. The interference of various diverse ions has been studied. The complex has 1:2 [Co(II)- HMBATSC] stoichiometry. A method for the determination of cobalt(II) by second order derivative spectrophotometry has also been proposed. The proposed methods were applied for the determination of cobalt(II) in alloy steels, vitamin B12 and in some biological samples.
Synthesis and Spectroscopic Studies of Metal Complexes Formed in the Reaction of Metal Ions with Urea at High Temperature
Gaballa, Akmal S. ; Teleb, Said M. ; Nour, El-Metwally ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 339~345
DOI : 10.5012/jkcs.2007.51.4.339
Urea reacts with PtCl2, H2[PtCl6]·6H2O, H2[IrCl6] and Ni(CH3CO2)2 in aqueous solution at high temperature (60-80 °C) yielding [PtCl2(Urea)]·2H2O (1), (NH4)2[PtCl6] (2), (NH4)2[IrCl6]·H2O (3) and [Ni2(OH)2(NCO)2(H2O)2] (4) complexes, respectively. In complex 1, urea coordinates to Pt(II) as a neutral bidentate ligand via amido nitrogen atoms. In complexes 2, 3 and 4 it seems that the coordinated urea molecules decompose during the reaction at high temperature and a variety of reaction products are obtained. All complexes were isolated in moderate yields as dark green (1), yellow (2), pale brown (3) and faint green (4) precipitates, respectively. The reaction products were characterized by their microanalysis, IR, 1H and 13C NMR spectra as well as thermal analysis. General mechanisms describing the formation of these complexes were suggested.
Dry Media Reaction Procedure for Synthesis of α,β-Unsaturated Acids, α-Cyanoacrylonitriles and α-Cyanoacrylates via Knoevenagel Condensation Using NaHSO
Gopalakrishnan, M. ; Sureshkumar, P. ; Kanagarajan, V. ; Thanusu, J. ; Thirunavukkarasu, S. ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 346~351
DOI : 10.5012/jkcs.2007.51.4.346
Efficient stereoselective synthesis of α,β-Unsaturated acids, α-Cyanoacrylonitriles and α-Cyanoacrylates has been carried out in the presence of NaHSO4·SiO2 under solvent?free conditions with an E-geometry.
3,7-Dihydroxy-2,4,6-trimethoxyphenanthrene, A New Phenanthrene from Bulbophyllum Odoratissimum
Chen, Ye-Gao ; Xu, Jun-Ju ; Yu, Hong ; Qing, Chen ; Zhang, Yan-Li ; Liu, Ying ; Wang, Ji-Hua ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 352~355
DOI : 10.5012/jkcs.2007.51.4.352
A new phenanthrene derivative 3,7-dihydroxy-2,4,6-trimethoxyphenanthrene was isolated from the all plant of Bulbophyllum odoratissimum, and its structure was elucidated by extensive spectral studies and chemical transformation. The compound displayed cytotoxicity against the growth of human leukemia cell lines K562 and HL-60, human lung adenocarcinoma A549, human hepatoma BEL-7402 and human stomach cancer cell lines SGC-7901 with IC50 values of 14.23, 10.02, 3.42, 15.36 and 1.13 mg/ml respectively.
One-pot Synthesis of 5,7-Diaryl-3,4,6-trihydronaphthalen-2-ones
Gopalakrishnan, M. ; Manikandan, H. ; Sureshkumar, P. ; Thanusu, J. ; Kanagarajan, V. ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 356~360
DOI : 10.5012/jkcs.2007.51.4.356
5,7-Diaryl-3,4,6-trihydronaphthalen-2-ones have been synthesized from 3,5-diaryl-cyclohex-2-en-1- ones and methyl vinyl ketone in the presence of sodium ethoxide. The products were characterized by IR, UV-Visible, 1H-NMR, 13C-NMR and mass spectral techniques. To confirm 1H and 13C signals, HSQC spectrum was recorded and analyzed.
One-Pot Efficient Beckmann Rearrangement of Ketones Catalyzed by Silica Sulfuric Acid
Eshghi, H. ; Hassankhani, A. ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 361~364
DOI : 10.5012/jkcs.2007.51.4.361
A one-pot Beckmann rearrangement for the preparation of amides from ketones is described using the silica sulfuric acid under Microwave irradiation. Advantages of this method are regioselectivity with high yields in a simple operation and short reaction time, in which the mole ratio of acid and ketone was 1:2 and it should be greener than the currently used systems.
Identification of High School Students' Understanding on the Reaction Rate Change During Chemical Equilibrium Shift
Park, Jong-Yoon ; Yu, Hyun-Hee ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 365~374
DOI : 10.5012/jkcs.2007.51.4.365
The purpose of this study is to investigate the students' conceptions about the reaction rate changes during the chemical equilibrium shifts and also whether the questions about basic concepts of the reaction rate are helpful for the students' understanding of reaction rate changes during the chemical equilibrium shifts. The subjects were 100 students in the 12th grade. The questionnaires were composed of A, B, and A' set, which had to be answered sequentially. The A set consisted of questions asking the change of reaction rate when chemical equilibrium was shifted, the B set was to testify the basic concepts of the reaction rate, and the A' set was the same as the A set. The results showed that the students' understanding of the reverse reaction rate change was lower than that of the forward reaction rate change during the equilibrium shift. Also it was found that students' understanding of the reaction rate change caused by adding the reactant was fairly good while their understanding of the reaction rate change caused by temperature increment was very poor. Since the students marked very high scores in the B set questions, their poor understanding for the reaction rate changes during the equilibrium shifts was not seemed to be due to the lacks of the basic knowledge of reaction rate. Instead, it was due to the failure of applying the basic knowledge of reaction rate to the changes of reaction conditions. It was also found that the average scores of A' set were statistically higher than those of A set. It means the B set items were helpful for the students to solve the A' set items. These results evidenced the possibility of set questionnaires could help the students to connect the related concepts in solving the problems.
Case Study on Verbal Interactions of Teacher-Small Group Students in Science Experiments
Seong, Suk-Kyoung ; Choi, Byung-Soon ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 375~386
DOI : 10.5012/jkcs.2007.51.4.375
The purpose of this study is to investigate the aspects of verbal interactions of teacher?small group students by categorizing those interactions which affect students' thinking thus to improve teacher's interaction. First, verbal interactions of teacher-small group students were divided into two categories ?Behaviors related to problem-solving, and Others. Behaviors related to problem-solving were also classified into two elements?Receiving opinion based on the students' thinking process, and Giving help based on the teacher's thinking process. Receiving opinion consists of agreement, question, correction, objection while giving help consists of information, hint, question, summary, and ask & answer. Most of teacher-small group students' interactions were in the form of teacher's questions and students' answers, and teacher's questions tended to require simple answers rather than answers from deep thought. In addition, there was a tendency that the teacher focused more on her own thinking process than students' and that she interacted with only a couple of students who gave correct answers. As a result, even after teacher's scaffolding, many students were often unable to understand the particular contents. However, through the interactions, the teacher made students to have confidence by restating their opinions and agreeing or praising them. She also created an atmosphere where students can give their opinions freely. From the observation of interactions, we can find that students' thinking process is affected by the characteristics of teacher's interactions such as expression of agreement and encouragement, hint giving rise to thought, interactions based on the students' thinking process, permission of students' activities and questions, allowing time for students' thought, and correction of wrong opinions. At this point, educational implications of teacher-small group students' interactions were drawn.
Study of Ring-Expansion of (η
-1,2,3,4,5- Pentamethyl-1,3-diborole)Cobalt Complex
Uhm, Jae-Kook ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 387~391
DOI : 10.5012/jkcs.2007.51.4.387
Conversion of meso diol Acetals to Chiral Hydroxy Benzyl Ethers by Chiral Auxiliary
Kim, Jin-Yeon ;
Journal of the Korean Chemical Society, volume 51, issue 4, 2007, Pages 392~397
DOI : 10.5012/jkcs.2007.51.4.392