• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3021-3024
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• 2014

The potential energy surface (PES) for the dissociation of the 2-hydroxypyridine (2-HP) radical cation was determined from G3//B3LYP calculations, including the loss of CO, HCN, and HNC. The formation of the 1H-pyrrole radical cation by decarbonylation through a more stable tautomer, the 2-pyridone (2-PY) radical cation, was the most favorable dissociation pathway. Kinetic analysis by the Rice-Ramsperger-Kassel-Marcus model calculations was carried out based on the obtained PES. It is proposed that the dissociation occurs after a rapid tautomerization to 2-$PY^{{\cdot}+}$, and that most of the ions generated by ionization of 2-HP have the structure of 2-$PY^{{\cdot}+}$ at equilibrium above the tautomerization barrier.

• Journal of Photoscience
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• 제7권3호
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• pp.109-110
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• 2000

No Abstract. See Full-text

• Bulletin of the Korean Chemical Society
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• 제23권9호
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• pp.1257-1262
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• 2002

$[(C_2B_9H_{11})Mo(CO)_3]_2PPN_2$ $(2{\cdot}PPN_2)$, a new precursor for the oxidative decarbonylation reaction, was synthesized in high yield by the one-electron oxidation reaction of $[(C_2B_9H_{11})Mo(CO)_3]PPN_2$. $2{\cdot}PPN_2$ was structurally characterized, showing a dimeric nature with long (3.321 ${\AA}$) Mo-Mo bonding. Reaction of $2{\cdot}PPN_2$ with sulfur gave the completely decarbonylated product $[(C_2B_9H_{11})Mo({\mu}-S)(S)]_2PPN_2$ ($3{\cdot}PPN_2$). The ligand substitution of the terminal sulfur ligands in $3{\cdot}PPN_2$ to oxygen ligands was carried out with the use of PhIO to give $[(C_2B_9H_{11})Mo({\mu}-S)(O)]_2PPN_2$ ($4{\cdot}PPN_2$). The structures of $3{\cdot}PPN_2$ and $4{\cdot}PPN_2$ were also studied.

• Bulletin of the Korean Chemical Society
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• 제20권1호
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• pp.85-88
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• 1999

Me3NO selectively abstracts the proton from [IrH(CO)(PPh3)2L(A)]0.1+,2+ (1) (A: -CCPh, Cl-, CH3CN and L: CH3CN, Cl-, C1O4-) to give the trans-elimination products, Ir(CO)(PPh3)2(A) (2). The reductive elimination of H+ and Cl- from Ir(H)Cl2(CO)(PPh3)2 (lb) to give IrCl(CO)(PPh3)2 (2b) is first order in both lb and Me3NO. The rate law d[2b]/dt=kobs[lb]=k2[lb][Me3NO] suggests the formation of (PPh3)2(CI)2(CO)Ir-H-ON+Me3 in the rate determining step (k2) followed by the fast dissociation of both H-ON+Me3 and the trans ligand Cl-. The rate significantly varies with the cis liaand A and the trans ligand L and is slower with both A and L being Cl- than other ligands. Me3NO selectively eliminates CO from [Ir(H)2(CO)(PPh3)2L]0,+ (3) (L=CH3CN, C1O4-) to produce [Ir(H)2(PPh3)2L'(CH3CN)]+ (4) (L'=CH3CN, PPh3) in the presence of L. Me3NO does not readily remove either H+ or CO from cis, trans- and trans, trans-lr(H)(-CCPh)2(CO)(PPh3)2 and cis, trans-Ir(H)2Cl(CO)(PPh3)2. The choice whether hydridocarbonyls, 1 and 3 undergo the deprotonation or decarbonylation may be understood mostly in terms of thermodynamic stability of the products and partly by kinetic preference of Me3NO on proton and CO.

• Journal of Photoscience
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• 제10권1호
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• pp.9-20
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• 2003

Recent studies on the photoreactivity of l,4-unsaturated systems have changed some ideas that were firmly established in this area of research for many years. Thus, we have described the first examples of 2-aza-di-$\pi$-methane (2-ADPM) rearrangements promoted by triplet-sensitization and by single electron transfer (SET) using electron-acceptor sensitizers. These reactions afford N-vinylaziridine and cyclopropylimine photoproducts in the first examples of di-$\pi$-methane processes that yield three-membered ring heterocycles. l-Aza-1,4-dienes also undergo SET-promoted l-aza-di-$\pi$-methane (l-ADPM) rearrangements via radical-cation intermediates using electron acceptor sensitizers. In some cases, alternative cyclizations yielding different carbocycles and heterocycles have been observed. The l-ADPM and di-$\pi$-methane (DPM) reactions also occur via radical-anion intermediates on irradiation using electron donor sensitizers. On the other hand, the photoreactivity reported for $\beta$,${\gamma}$-unsaturated aldehydes for many years was decarbonylation to the corresponding alkenes. However, our studies demonstrate that these compounds undergo the oxa-di-$\pi$-methane (ODPM) rearrangement with high chemical and quantum efficiency. A comparison of the photochemical reactivity of $\beta$,${\gamma}$-unsaturated aldehydes and corresponding methyl ketones has shown that the ketones do not undergo the ODPM rearrangement while the corresponding aldehydes are reactive by this pathway. Monosubstituted $\beta$,${\gamma}$-unsaturated aldehydes at C-2 undergo the ODPM rearrangement yielding the corresponding cyclopropane carbaldehydes diastereoselectively. Finally, we have described the first examples of reactions, similar to the well know Norrish Type I process, which take place in the triplet excited state of $\beta$,${\gamma}$-unsaturated carbonyl compounds by excitation of the C-C double bond instead of the carbonyl group.

• Advances in Energy Research
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• 제8권4호
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• pp.223-231
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• 2022

An ex-situ gravitational fixed bed pyrolysis reactor was used over Al₂O₃ supported Ni₂P based catalyst with various Ni/P molar ratios (0.5-2.0) and constant nickel loading of 5.37 mmol/g Al₂O₃ to determine the hydrodeoxygenation of rubberwood sawdust (RWS) at atmospheric pressure. The 3D catalysts formed were characterized structurally as well as acidic properties were determined by hydrogen-temperature programmed reduction (TPR). The Ni₂P phase formed completely on Al₂O₃ for 1.5 Ni/P ratio, although lesser crystallite sizes of Ni₂P were seen at Ni/P ratios less than 1.5. Additionally, it was shown that when nickel loading level increased, acidity increased and specific surface area dropped, probably because nickel phosphate is not easily converted to Ni₂P. When Ni/P ratio was 1.5, Ni₂P phase fully formed on Al₂O₃. The catalytic activity was explained in terms of impacts of reaction temperature and Ni/P molar ratio. At relatively high temperature of 450℃, the high-value deoxygenated produce was predominantly composed of n-alkanes. Based on the findings, it was suggested that hydrogenolysis, hydrodeoxygenation, dehydration, decarbonylation, and hydrogenation are all part of mechanism underlying hydrotreatment of RWS. In conclusion, the synthesized Ni₂P/ Al₂O₃ catalyst was capable of deoxygenating RWS with ease at atmospheric pressure, primarily resulting in long chained (C₉-C₂₄) hydrocarbons and acetic acid.

• 청정기술
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• 제29권3호
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• pp.200-216
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• 2023

은행잎은 자체에 존재하는 ginkgolide A, B, C, J 및 bilobalide의 강한 살충작용으로 인해 제대로 분해가 진행되지 않아 그대로 방치할 시 사고를 유발 할 수 있는 폐기물 바이오매스이다. 은행잎 바이오매스는 적절한 기술 적용을 통해 연료나 화학물질로 전환할 수 있다. 본 연구에서는 은행잎의 급속 열분해 반응과정에서 열분해 온도, 최소 유동화 속도, 샘플의 크기를 변화 시키면서 생성물 특성에 대한 연구를 수행하였다. 열분해 온도 400~550℃, 최소 유동화 속도 2.0~4.0 U_mf, 그리고 바이오매스 샘플의 크기에 변화 따라 생성물의 수율과 특성의 변화를 확인하였다. 급속 열분해는 기포 유동층 반응기에서 모래를 층 물질로 사용하여 400~500℃ 구간에서 진행하였다. 열분해 후 액상 생성물의 수율은 온도에 따라 33.66~40.01 wt%였으며, 기상 생성물 중 CO₂와 CO의 선택성이 높았고, 온도 증가에 따라 CO₂의 선택성은 낮아지고 CO의 선택성은 높아졌다. 반응 온도 450℃, 유동화 속도 3.0×U_mf, 0.43~0.71 mm 입자 크기에서 급속 열분해를 진행한 결과 40.01 wt%의 바이오-오일 수율을 얻었으며, 30.17 MJ/kg의 고위발열량을 나타냈다. 생성된 바이오-오일을 GC-MS를 통해 분석해본 결과 다양한 페놀 화합물 및 벤젠 유도체가 생성된 것을 확인하였다. 본 연구에서 은행잎 폐기물 바이오매스의 처리와 함께 활용 가능성을 급속 열분해를 통해 확인하였다.