检索结果-南通市图书馆

Chinese Journal of Chemical Physics 2011年第5期24卷 580-585,I0004页

作者：刘坤辉吴丽丹邹笑然杨文杜谦苏红梅中国科学院化学研究所分子反应动力学国家重点实验室、北京分子科学国家实验室北京100190

Pentachlorophenol, a widespread environmental pollutant that is possibly carcinogenic to humans, is metabolically oxidized to tetrachloroquinone （TCBQ） which can result in DNA damage. We have investigated the photochemical reaction dynamics of TCBQ with two pyrimidine type nucleobases （thymine and uracil） upon UVA （355 ran） excitation using the technique of nanosecond time-resolved laser flash photolysis. It has been found that 355 nm excitation populates TCBQ molecules to their triplet state 3TCBQ＊, which are highly reactive towards thymine or uracil and undergo two parallel reactions, the hydrogen abstraction and electron transfer, leading to the observed photoproducts of TCBQH. and TCBQ.- in transient absorption spectra. The concomitantly produced nucleobase radicals and radical cations are expected to induce a series of oxidative or strand cleavage damage to DNA afterwards. By characterizing the photochemical hydrogen abstraction and electron transfer reactions, our results provide potentially important molecular reaction mechanisms for understanding the carcinogenic effects of pentachlorophenol and its metabolites TCBQ.

关键词： Tetrachlorobenzoquinone Thymine Uracil Triplet state hydrogen abstraction Electron transfer Laser flash photolysis

Theoretical Study on Gas Phase Reactions of OH hydrogen-abstraction from Formyl Fluoride with Different Catalysts

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2016年第3期29卷 325-334,I0001页

作者：王定美隆正文谭兴凤龙波张为俊贵州大学物理系贵阳550025 贵州民族大学信息工程学院贵阳550025 中国科学院安徽光学精密机械研究所环境光学实验室合肥230031 中国科学院安徽光学精密机械研究所大气成分与光学重占章验室合肥230031

The mechanisms and kinetics of the gas phase reactions that the hydrogen atom in formyl fluoride （FCHO） abstracted by OH in the presence of water, formic acid （FA）, or sulfuric acid （SA） are theoretically investigated at the CCSD（T）/6-311＋＋G（3df, 3pd）//MO6-2X/6- 311＋＋G（3df, 3pd） level of theory. The calculated results show that the barriers of the transition states involving catalysts are lowered to -2.89, -6.25, and -7.76 kcal/mol from 3.64 kcal/mol with respect to the separate reactants, respectively, which reflects that those catalysts play an important role in reducing the barrier of the hydrogen abstraction reaction of FCHO with OH. Additionally, using conventional transition state theory with Eckart tun- neling correction, the kinetic data demonstrate that the entrance channel X…FCHO＋OH （X=H2O, FA, or SA） is significantly more favorable than the pathway X…OH＋FCHO. More- over, the rate constants of the reactions of FCHO with OH radical with H2O, FA, or SA introduced are computed to be smaller than that of the naked OH＋FCHO reaction because the concentration of the formed X…FCHO or X…OH complex is quite low in the atmosphere.

关键词： Formyl fluoride hydrogen abstraction Reaction mechanisms Rate constants

Theoretical study of propene oxidation on Bi_2O_3 surfaces

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2015年第4期58卷 593-600页

作者： Yan-Hua Lei Zhao-Xu Chen Key Laboratory of Mesoscopic Chemistry Ministry of Education Institute of Theoretical and Computational Chemistry School of Chemistry and Chemical Engineering Nanjing University

The role of bismuth in the selective oxidation of propene has long been debated. We performed density functional calculations to study the dehydrogenation reaction of propene on Bi203 surfaces. Our calculated thermodynamic data reveal that the first dehydrogenation of propene on the most stable （010） surface and the （100） surface are difficult. Our calculations indicate that the barrier of the first hydrogen abstraction on the high Miller index surface （211） is much lower than those on the （100） and （010） surfaces, and is close to the experimental one. Further dehydrogenation is shown to be difficult and production of 1,5-hexadiene through dimerization of allyl is likely, in agreement with the experimental observations.

关键词： hydrogen abstraction oxidation propene Bi2O3 surfaces reaction mechanism density functional theory

Theoretical Studies on the Reaction Mechanism of Hydroxyl Radical with 1,1,1-Trichloroethane

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2011年第8期30卷 1199-1206页

作者：胡晓萍王丙星高颖杨兵 College of Chemistry and Chemical Engineering Harbin Normal University State Key Laboratory of Supramolecular Structure and Materials Jilin University

Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical （OH） and 1,1,1-trichloroethane （CH3CCl3）. The potential energy surface has been given according to the relative energies calculated at the MP2/cc-pVTZ level after the spin projection （PMP2）. Five reaction channels were identified and the intramolecular hydrogen bonding was observed in some transition state structures. The barrier heights and reaction enthalpies calculated for all possible channels show that the hydrogen abstraction channel is predominant kinetically and thermodynamically. The contribution from other channels was predicted to be minor.

关键词： hydroxyl radical 1 1 1-trichloroethane hydrogen abstraction intramolecular bonding transition state PMP2

CIDNP study of the photochemistry of 1-acetylindole-2,3-dione

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2005年第2期48卷 115-121页

作者： GUO Hongling YAN Baozhen WANG Xinyan WANG Ting School of Science Beijing University of Chemical Technology Beijing 100029 China School of Science Beijing University of Chemical Technology Beijing 100029 China School of Science Beijing University of Chemical Technology Beijing 100029 China School of Science Beijing University of Chemical Technology Beijing 100029 China

Chemically Induced Dynamic Nuclear Polarization (CIDNP) technique is applied to study the photochemical reactions of 1-acetylindole-2,3-dione (AID) with several hydrogen do- nors (1—13). These reactions take place by direct hydrogen abstraction of triplet excited AID from the corresponding 1—13 to give neutral radical pair intermediates, which afford polarized starting materials by back hydrogen transfer and give polarized coupling products by radical pair recombination.

关键词： acetylindole-2,3-dione CIDNP electron transfer hydrogen abstraction photochemistry.

Reaction-path Dynamics and Theoretical Rate Constants for the Reaction of CH_3CH_2OCF_3 with HOOO Radical

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2015年第2期34卷 167-178页

作者：杨静 Department of Chemistry Tangshan Normal College

A dynamic method is employed to study the reaction mechanisms of CH3CH2OCF3 with the hydrogen trioxy （HOOO） radical. In our paper, the geometries and harmonic vibrational frequencies of all the stationary points and minimum energy paths （MEPs） are calculated at the MPW1K/6-31＋G（d,p） level of theory, and the energetic information along MEPs is further refined by the CCSD/6-31＋G（df, p） level of theory. The rate constants are evaluated with the conventional transition-state theory （TST）, the canonical variational transition-state theory （CVT）, the microcanonical variational transition-state theory （μVT）, the CVT coupled with the small-curvature tunneling （SCT） correction （CVT/SCT）, and the μVT coupled with the Eckart tunneling correction μVT/Eckart） based on the ab initio calculations in the temperature range of 200-3000 K. The theoretical results are important in determining the atmospheric lifetime and the feasible pathways for the loss of HFEs.

关键词： hydrogen abstraction hydrogen trioxy CH3CHzOCF3 rate constants ab initio

Laser Flash Photolysis Mechanism of Anthraquinone-2-Sodium Sulfonate in Pyridine Ionic Liquid/Water Mixed System

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2016年第1期29卷 140-146,I0003页

作者：朱光来张良伟刘艳成崔执凤许新胜吴国忠安徽师范大学原子与分子物理研究所芜湖241000 中国科学院上海应用物理研究所上海201800

The photochemical reaction process of anthraquinone-2-sodium sulfonate （AQS） in the mixture of water （H2O） and N-butylpyridinium tetrafluoroborate （[BPy] [BF4]） was studied using the laser flash photolysis technique. Experimental results show that the excited triplet of AQS （3AQS＊） could react rapidly with H2O and the transient absorption spectra greatly changed by increasing the volume fraction of the ionic liquid （VIL） in [BPy][BF4]/H2O mixtures. The absorbance at 510 nm increased gradually with increasing VIL when 0〈VIL〈0.1. By contrast, the absorbance decreased gradually when VIL〉0.1. Otherwise, the absorbance of the band near 380 nm steadily increased. The apparent kinetic parameters of transient species B and ^3AQS＊ are obtained approximately. 3AQS＊ abstracting hydrogen from [BPy]＋ was also explored. It was deduced that the 350-420 nm band was the superposition of the peaks of 3AQS＊ and AQSH＇. The two reactions of 3AQS＊ with [BPy][BF4] and H2O are a pair of competitive reactions. We also concluded that the entire reaction processes slow down in the case of high [BPy] [BF4] concentrations.

关键词： Laser flash photolysis Anthraquinone-2-sodium sulfonate Ionic liquids Tran- sient absorption hydrogen abstraction