• Title/Summary/Keyword: $^{13}C-NMR$ 분석

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Atomic Structure of Dissolved Carbon in Enstatite: Raman Spectroscopy and Quantum Chemical Calculations of NMR Chemical Shift (라만 분광분석과 NMR 화학 이동 양자 계산을 이용한 엔스테타이트에 용해된 탄소의 원자 환경 연구)

  • Kim, Eun-Jeong;Lee, Sung-Keun
    • Journal of the Mineralogical Society of Korea
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    • v.24 no.4
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    • pp.289-300
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    • 2011
  • Atomistic origins of carbon solubility into silicates are essential to understand the effect of carbon on the properties of silicates and evolution of the Earth system through igneous and volcanic processes. Here, we investigate the atomic structure and NMR properties of dissolved carbon in enstatite using Raman spectroscopy and quantum chemical calculations. Raman spectrum for enstatite synthesized with 2.4. wt% of amorphous carbon at 1.5 GPa and $1,400^{\circ}C$ shows vibrational modes of enstatite, but does not show any vibrational modes of $CO_2$ or ${CO_3}^{2-}$. The result indicates low solubility of carbon into enstatite at a given pressure and temperature conditions. Because $^{13}C$ NMR chemical shift is sensitive to local atomic structure around carbon and we calculated $^{13}C$ NMR chemical shielding tensors for C substituted enstatite cluster as well as molecular $CO_2$ using quantum chemical calculations to give insights into $^{13}C$ NMR chemical shifts of carbon in enstatite. The result shows that $^{13}C$ NMR chemical shift of $CO_2$ is 125 ppm, consistent with previous studies. Calculated $^{13}C$ NMR chemical shift of C is ~254 ppm. The current calculation will alllow us to assign potential $^{13}C$ NMR spectra for the enstatite dissolved with carbon and thus may be useful in exploring the atomic environment of carbon.

The Laccase Activity of Trametes versicolor during Cultivation on Acetylated Wood and 13C-CP/MAS NMR Study (아세틸화 처리 목재에 배양시킨 Trametes versicolor의 Laccase활성과 13C-CP/MAS NMR 분석)

  • Son, Dong-Won;Lee, Dong-Heub
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.4
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    • pp.60-66
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    • 2001
  • For examine anti-degradation factors of acetylated wood, acetylated wood was incubated on Trametes versicolor. The laccase activity was examined in broth culture and solid fermentation that contain acetylated chips. The change of acetyl groups and chemical composition in the acetylated wood having massloss analysed by $^{13}C$-CP/MAS NMR. The laccase activity was detected in broth culture. When the T. versicolor contact to acetylated wood directly, the laccase activity was very low and couldn't maintain during test periods. Through the analysing of $^{13}C$-CP/MAS NMR, the acetylation took place carbohydrates as well as lignin and hydroxyl group of amorphous region was more easily substituted that of crystalline region The spectral analyses of $^{13}C$-CP/MAS NMR were shown that introduced acetyl bond was stable against fungal attack.

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$A^{13}$ CNMR Determination of Monomer Composition in EP Copolymers, EPB and EPDM Terpolymers (EP 공중합체, EPB 및 EPDM 삼중합체의 단량체조성에 관한 $^{13}C$-NMR 분석)

  • Lee, Kang-Bong;An, Seong-Uk;Rhee, Jae-Seong;Kweon, Jeehye;Choi, Young-Sang
    • Analytical Science and Technology
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    • v.7 no.1
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    • pp.91-102
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    • 1994
  • The monomer compositions in a series of propylene heterophasic copolymer, propylene random copolymer, propylene random terpolymer and ethylene-propylene-ENB terpolymer have been determined from $^{13}C-NMR$ spectra. The simplified and highly resolved $^{13}C-NMR$ spectra made it possible to assign unambiguousely and calculate the monomer composition. A complete sets of NMR chemical shift assignments and the way to measure the quantity of monomer are newly given in diverse polymers. Furthermore complete dyad, triad, tetrad and pentad distributions have been able to be determined. These NMR quantitative analytical results for monomer compostition have consistent with those from Infrared spectral data.

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Investigation of Gas Hydrate Crystallization and Structure Analysis by $^{13}C$ NMR with Surfactant (계면활성제 첨가에 따른 가스하이드레이트 생성 결정과 $^{13}C$ NMR 구조 분석 고찰)

  • Cho, Byoung-Hak;Lee, Young-Chul;Shin, Myung-Uk;Lee, Sung-Han
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.395-398
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    • 2006
  • 동일한 조건에서 순수한 물과 계면활성제인 DBS(dodecyl bezebe sulfonic acid) 25ppm을 첨가한 물에 대해 천연가스 하이드레이트를 제조시 가스의 함유량은 각각 80배와 160배로 2배의 차이가 발생한다. 이에 대해 본 연구에서는 결정 생성 형태의 관찰 및 $^{13}C$ NMR을 사용한 분광학적 구조 분석으로부터 이의 원인을 찾고자 하였다. 순수한 물과 DBS를 미량 함유한 물을 사용하여 whiskery 결정을 생성시킨 결과, 순수한 물을 사용한 경우보다 섬유 다발 형태가 매우 활발한 형태의 결정 형태로 가스하이드 레이트가 생성됨을 알 수 있었다. 또한 400MHz의 NMR을 사용한 분광학적 구조 분석으로부터 천연가스하이드레이트는 구조-I과 구조-II가 혼재된 결정 구조를 이루고 있음을 알 수 있었다. 또한 DBS를 함유한 물에 의해 제조된 천연가스하이드레이트는 arge cage를 많이 생성시키는 역할을 하는 분석 결과를 보였고 이것이 가스 함유량을 증대시키는 원인 중의 하나임을 알 수 있었다.

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Structural Analysis of Petroleum Fractions by Near-Infrared and $^{13}C$-NMR Spectroscopy (근적외선과 $^{13}C$-핵자기 공명 분광학에 의한 석유유분 구조분석)

  • Choi, Ju-Hwan;Kim, Hai-Dong;Choi, Young-Sang
    • Analytical Science and Technology
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    • v.9 no.2
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    • pp.168-178
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    • 1996
  • Molecular structures of petroleum fractions(diesel fuel, bunker-C oil, lubricant base stocks) have been analyzed and compared in terms of the compositions (aromatics, naphtherucs, paraffinics), aromatics(benzene-nuclear and bonded alkyl groups), C2(methylene) carbon atoms % $C_{\alpha}$ and $C_{\beta}$ carbon stom % in alkyl groups and paraffins(branched and normal) by near-infrared and $^{13}C$-NMR spectroscopy.

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Synthesis and Analysis of 6,6-dichlorobicyclo[3, 1, 0]hexane-3-carboxylic acid (6,6-Dichlorobicyclo[3, 1, 0]hexane-3-carboxylic acid의 합성과 분석)

  • Lee, Kwang-Soo;Yang, Jae-Kun
    • Analytical Science and Technology
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    • v.14 no.1
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    • pp.1-7
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    • 2001
  • 6,6-Dichlorobicyclo[3, 1, 0]hexane-3carboxylic acid was synthesized by dichlorocarbene addition into 3-cyclopentenecarboxylic acid using BTEA.Cl as phase transfer catalyst. $^1H$ NMR $^{13}C$ NMR data analyst showed that this compound had boat-like conformation and carboxyl group existed as trans form.

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Characterization of Kraft Lignin by 13C-Nuclear Magnetic Resonance Spectroscopy (13C-NMR에 의한 크라프트 리그닌의 특성)

  • Lee, Beom-Goo;Hwang, Byung-Ho
    • Journal of the Korean Wood Science and Technology
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    • v.17 no.4
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    • pp.44-56
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    • 1989
  • To recover much residual lignin from the black liquor of kraft pulp. the black liquor was extracted and purified with many organic solvents. Many kinds of lignins were isolated from each fraction obtained and the characteristics of these lignins investigated by $^{13}C$-NMR spectroscopy. If M$\ddot{o}$rck's method was compared with Kirk's method. M$\ddot{o}$rck's method was better than Kirk's method because the particular signals of each lignin occur more in the former than m the latter. Especially the $^{13}C$-NMR spectrum of the MCS fraction identifies with those of other researchers. The experiment that the kraft lignin from Pinus densiflora S. et Z. found in Korea was investigated by $^{13}C$-NMR spectroscopy was performed first in Korea.

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Microstructure of Polypropylene Prepared with Kaminsky Catalyst System (Kaminsky 촉매계로 제조한 폴리프로필렌의 미세구조)

  • Lee, Cheal-Gyu
    • Analytical Science and Technology
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    • v.9 no.2
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    • pp.203-209
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    • 1996
  • Kaminsky catalyst system($Et(Ind)_2ZrCl_2$ and MAO(methylaluminoxane)) was prepared. Propylene was polymerized at $60^{\circ}C$ in this system. The microstructure was studied by using the $^{13}C$ NMR spectrometer. From the $^{13}C$ NMR data, the 2, 1-insertion of propylene was controlled stereospecific by Kaminsky catalyst due to the structures of meso and racemo I. After the 2, 1-insertion of propylene, 1, 2-insertion of the chain end was less stereospecifically controlled by the catalyst.

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INTRINSIC NMR ISOTOPE SHIFTS OF CYCLOOCTANONE AT LOW TEMPERATURE (저온에서의 싸이클로옥타논에 대한 고유동위원소 효과)

  • Jung, Miewon
    • Analytical Science and Technology
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    • v.7 no.2
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    • pp.213-224
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    • 1994
  • Several isotopomers of cyclooctanone were prepared by selective deuterium substitution. Intrinsic isotope effects on $^{13}C$ NMR chemical shifts of these isotopomers were investigated systematically at low temperature. These istope effects were discussed in relation to the preferred boat-chair conformation of cyclooctanone. Deuterium isotope effects on NMR chemical shifts have been known for a long time. Especially in a conformationally mobile molecule, isotope perturbation could affect NMR signals through a combination of isotope effects on equilibria and intrinsic effects. The distinction between intrinsic and nonintrinsic effects is quite difficult at ambient temperature due to involvement of both equilibrium and intrinsic isotope effects. However if equilibria between possible conformers of cyclooctanone are slowed down enough on the NMR time scale by lowering temperature, it should be possible to measure intrinsic isotope shifts from the separated signals at low temperature. $^{13}C$ NMR has been successfully utilized in the study on molecular conformation in solution when one deals with stable conformers or molecules were rapid interconversion occurs at ambient temperature. The study of dynamic processes in general requires analysis of spectra at several temperature. Anet et al. did $^1H$ NMR study of cyclooctanone at low temperature to freeze out a stable conformation, but were not able initially to deduce which conformation was stable because of the complexity of alkyl region in the $^1H$ NMR spectrum. They also reported the $^1H$ and $^{13}C$ NMR spectra of the $C_9-C_{16}$ cycloalkanones with changing temperature from $-80^{\circ}C$ to $-170^{\circ}C$, but they did not report a variable temperature $^{13}C$ NMR study of cyclooctanone. For the analysis of the intrinsic isotope effect with relation to cylooctanone conformation, $^{13}C$ NMR spectra are obtained in the present work at low temperatures (up to $-150^{\circ}C$) in order to find the chemical shifts at the temperature at which the dynamic process can be "frozen-out" on the NMR time scale and cyclooctanone can be observed as a stable conformation. Both the ring inversion and pseudorotational processes must be "frozen-out" in order to see separate resonances for all eight carbons in cyclooctanone. In contrast to $^1H$ spectra, slowing down just the ring inversion process has no apparent effects on the $^{13}C$ spectra because exchange of environments within the pairs of methylene carbons can still occur by the pseudorotational process. Several isotopomers of cyclooctanone were prepared by selective deuterium substitution (fig. 1) : complete deuterium labeling at C-2 and C-8 positions gave cyclooctanone-2, 2, 8, $8-D_4$ : complete labeling at C-2 and C-7 positions afforded the 2, 2, 7, $7-D_4$ isotopomer : di-deuteration at C-3 gave the 3, $3-D_2$ isotopomer : mono-deuteration provided cyclooctanone-2-D, 4-D and 5-D isotopomers : and partial deuteration on the C-2 and C-8 position, with a chiral and difunctional case catalyst, gave the trans-2, $8-D_2$ isotopomer. These isotopomer were investigated systematically in relation with cyclooctanone conformation and intrinsic isotope effects on $^{13}C$ NMR chemical shifts at low temperature. The determination of the intrinsic effects could help in the analysis of the more complex effects at higher temperature. For quantitative analysis of intrinsic isotope effects, the $^{13}C$ NMR spectrum has been obtained for a mixture of the labeled and unlabeled compounds because the signal separations are very small.

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