• 제목/요약/키워드: proton transfer

검색결과 239건 처리시간 0.026초

Oxidative N-Debenzylation of N-Benzyl-N-substituted Benzylamines Catalyzed by Cytochrome P450

  • Kim, Sung-Soo;Lin, Gang;Yang, Ji-Won
    • Bulletin of the Korean Chemical Society
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    • 제25권2호
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    • pp.249-252
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    • 2004
  • Cytochrome P450 (P450)/$O_2$/NADPH engender electron transfer reaction of N-benzyl-N-substituted benzylamines to yield corresponding radical cation 1 that is simultaneously converted into 2 and 3. Subsequently, expulsion of proton and hydroxylation yielding a-hydroxylamines are followed by formation of benzaldehydes and benzylamines.

Synthesis of Dienamides via the Reaction of Nitrile with Allylindium Reagents and Intramolecular Acyl Group Quenching Cascade

  • Kim, Sung-Hwan;Kim, Yu-Mi;Kim, Jae-Nyoung
    • Bulletin of the Korean Chemical Society
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    • 제31권8호
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    • pp.2351-2356
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    • 2010
  • Various dienamide derivatives were synthesized in reasonable yields from benzonitriles having an amide moiety at the ortho-position, via the sequential (i) In-mediated allylation of nitrile moiety to form an imine intermediate, (ii) intramolecular quenching of an acyl group by the imine intermediate, and (iii) a proton transfer to dienamide.

Study of rganized Assemblies and Surfaces Using Picosecond Lasers

  • Bhattacharyya, Kankan
    • Journal of Photoscience
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    • 제6권3호
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    • pp.123-128
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    • 1999
  • Dynamics of many ultrafast processes are markedly slowed down in various organized molecular assemblies compared to ordinary liquids. We will show that the solvation dynamics of water molecules is affected amost dramatically and is retarded by 3 ∼4 orders of magnitude in microemulsions, micells and lipids. We will also discuss how the access to fewer water molucules and the drastically altered local pH in an organized asembly affected the excited state proton transfer processes. Finally, we will show how surface second haromonic generation can be used to study the air-water surface.

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Photoionization of N,N,N',N'-Tetramethyl-p-phenylenediamine in Polar Solvents

  • Min Yeong Lee;Du Jeon Jang;Minyung Lee;Du-Jeon Jang;Dongho Kim;Sun Sook Lee;Bong Hyun Boo
    • Bulletin of the Korean Chemical Society
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    • 제12권4호
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    • pp.429-433
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    • 1991
  • The photoinduced electron transfer reactions of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in various polar solvents were studied by measuring time-resolved fluorescence. The temperature dependence on the fluorescence decay rate in acetonitrile, methanol, ethanol and buthanol was carried out to obtain the activation energy and Arrehnius factor for the photoinduced electron transfer reaction. It was found that as the dielectric constant of the solvent increases, the activation energy and the reaction rate increase. This implys that the Arrehnius factor is important in controlling the photoinduced electron transfer reaction rate. In water, TMPD exists in three forms (cationic, protonated and neutral forms) due to the high dielectric constant and strong proton donating power of water. The photoinduced electron transfer reaction was found to be very fast (< 50 ps) and also the long liverd component in the fluorescence decay profile attributable to the photoexcited protonated form of TMPD was observed. Probably, the reaction pathway and the reaction coordinate seem to be different depending on the solvents studied here.

Thermal study of a scanning beam in granular flow target

  • Ping Lin;Yuanshuai Qin;Changwei Hao;Yuan Tian ;Jiangfeng Wan ;Huan Jia ;Lei Yang ;Wenshan Duan ;Han-Jie Cai ;Sheng Zhang
    • Nuclear Engineering and Technology
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    • 제54권11호
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    • pp.4310-4321
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    • 2022
  • The concept of dense granular-flow target (DGT) for the China Initiative Accelerator Driven Subcritical system (CiADS) is an attractive choice for high heat removal ability, low chemical toxicity, and radiotoxicity. A wobbling hollow beam is proposed to enhance the homogeneity of temperature rise of flowing particles in beam-target coupling zone. In this paper, the design procedure of target and beam parameters was discussed firstly. Then we simulated the heat deposition and transfer of the scanning beam in DGT to study the effect of beam parameters. The results show the flux density of proton beam plays a crucial role in the distribution of temperature rise while the contributions from scanning frequency heat transfer are also obvious. Moreover, heat transfer in transversal directions is insignificant, resulting in a low heat flux towards the sidewalls of DGT. This work not only contributes to the design of DGT, but also beneficial for understanding the beam-target coupling in porous materials.

Effects of Electrolytes in a Liquid Thin Layer System

  • Chung, Taek-Dong
    • 전기화학회지
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    • 제5권4호
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    • pp.216-220
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    • 2002
  • The effects of electrolytes on electrochemical behavior from an oil thin layer interposed between a graphite electrode and an aqueous solution phase were examined. A hydrophobic electroactive species, tetrachloro-1,4-benzoquinone (TCQ), in a benzonitrile (EN) layer was employed to study ion transfer properties across the BN-water interface. Experimental results showed that hydrophobic cations as well as anions could be successfully used as ionic charge carriers. The addition of various salts into either the oil layers or the aqueous solutions offers deeper insight for the electrochemistry of the liquid thin layer system. When aqueous perchloric acid is interfaced with the BN films, the perchlorate ion of tetrahexylammonium perchlorate (THAP) substantially suppresses the dissociated proton concentration in the layer by the common ion effect while there is only a little change in the total acid concentration. Further approach by theoretical calculation makes it possible to quantitatively understand the effect of the electrolytes to the electrochemical responses of TCQ, which were previously reported (Anal. Chem. 73, 337 (2001)).

Radiative Transfer in Highly Thick Media through Rayleigh and Raman Scattering with Atomic Hydrogen

  • Chang, Seok-Jun
    • 천문학회보
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    • 제46권2호
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    • pp.40.1-40.1
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    • 2021
  • Hydrogen is the most abundant element in the universe, which is, in the cosmological context, attributed to its simplest structure consisting of a proton and an electron. Hydrogen interacts with an electromagnetic wave in astrophysical environments. Rayleigh scattering refers to elastic scattering, where the frequencies of the incident and scattered photons are the same. Rayleigh and resonance scattering is a critical role study Lyman Alpha objects in the early universe. The scattering causes the frequency and spatial diffusion of Lyα. In the case of Raman scattering, the energies of the incident and scattered photons are different. The photons near Lyβ convert to the optical photons near Hα through Raman scattering. The photon scattered by atomic hydrogen can carry both of the properties of the H I region and the emission region. I adopt a Monte Carlo approach to investigate the formation of the various spectral line features through Rayleigh and Raman scattering in highly thick media of atomic hydrogen. In this thesis, I present my works on radiative transfer involving the scattering processes between far UV photon and atomic hydrogen. I introduce scattering processes with atomic hydrogen and the spectral, spatial, and polarized information originating from the scattering.

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양자전이 비행시간 질량분석기를 이용한 화학사고 원인물질 분석 (Analysis of Chemical Accident-Causing Substances Using a Proton Transfer Reaction-Time of Flight Mass Spectrometer)

  • 김소영
    • 한국화재소방학회논문지
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    • 제33권6호
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    • pp.80-86
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    • 2019
  • 국내에서는 2012년부터 2018년 까지 총 556건의 화학사고가 발생하였다. 화학사고 중 두 가지 이상의 화학물질 이상반응에 의해 발생하는 사고는 그 원인물질을 파악하는데 많은 시간이 필요하여 효과적인 사고대응과 수습을 위해서 신속한 분석이 필요하다. 본 논문은 이상반응에 의해 발생한 화학사고의 원인물질 파악을 위해 양자전이 비행시간 질량분석기를 사용하였다. 이 분석기는 시료채취와 전처리 없이 빠른 응답시간을 가져 실시간 분석이 가능하며 또한 수소친화도가 높은 대부분의 휘발성유기화합물질의 정량·정성 분석이 가능하여 이상반응에 의해 발생되는 화학사고의 원인 물질을 조사하는데 적합하다. 실제로 201◯년 ◯월에 ◯◯ 지역 화학사고 발생 시 양자전이 비행시간 질량분석기를 이용하여 측정한 결과 메탄올과 톨루엔 등이 검출되는 것을 알았으며 이상반응에 의해 발생된 황 계열 화합물이 사고 주변의 강한 악취의 원인임을 알 수 있었다.