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The reaction kinetics of aqueous oxidation of H2S by Fe+3 is investigated at 25°C by spectrophotometric method. The study conducted at various reactant concentrations and pH revealed that the reaction proceeds according to complex‐series reactions involving polysulfides as intermediates. The reaction of each step is first order with respect to Fe+3 and hydrogen sulfide or polysulfide. A mechanism is proposed, involving sulfido and polysulfido radicals. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 331–335, 1999 相似文献
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The reactions of trimethylindium (TMIn) with H2O and H2S are relevant to the chemical vapor deposition of indium oxide and indium sulfide thin films. The mechanisms and energetics of these reactions in the gas phase have been investigated by density functional theory and ab initio calculations using the CCSD(T)/[6-31G(d,p)+Lanl2dz]//B3LYP/[6-31G(d,p)+Lanl2dz] and CCSD(T)/[6-31G(d,p)+Lanl2dz] //MP2/[6-31G(d,p)+Lanl2dz] methods. The results of both methods are in good agreement for the optimized geometries and relative energies. When TMIn reacts with H2O and H2S, initial molecular complexes [(CH3)3In:OH2 (R1)] and [(CH3)3In:SH2 (R2)] are formed with 12.6 and 3.9 kcal/mol binding energies. Elimination of a CH4 molecule from each complex occurs with a similar energy barrier at TS1 (19.9 kcal/mol) and at TS3 (22.1 kcal/mol), respectively, giving stable intermediates (CH3)2InOH and (CH3)2InSH. The elimination of the second CH4 molecule from these intermediate products, however, has to overcome very high and much different barriers of 66.1 and 53.2 kcal/mol, respectively. In the case of DMIn with H2O and H2S reactions, formation of both InO and InS is exothermic by 3.1 and 30.8 kcal/mol respectively. On the basis of the predicted heats of formation of R1 and R2 at 0 K and -20.1 and 43.6 kcal/mol, the heats of formation of (CH3)2InOH, (CH3)2InSH, CH3InO, CH3InS, InO, and InS are estimated to be -20.6, 31.8, and 29.0 and 48.4, 35.5, and 58.5 kcal/mol, respectively. The values for InO and InS are in good agreement with available experimental data. A similar study on the reactions of (CH3)2In with H2O and H2S has been carried out; in these reactions CH3InOH and CH3InSH were found to be the key intermediate products. 相似文献
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Takashi Tatsumi Yosiaki Watanabe Yoshiro Hirasawa Junichi Tsuchiya 《Research on Chemical Intermediates》1998,24(5):529-540
Metallosilicate zeolites containing Ti and V, TS-2 and VS-2, have been synthesized using tetrabutylammonium cation as the
template. Although both Ti and V exist in zeolite framework in a highly dispersed state, V easily leaches by K2CO3 or H2O2 treatments in contrast to Ti. Spin trapping experiments and relative reactivity of linear/cyclic alkanes indicate that the
oxidation of alkanes over TS-2 and VS-2 proceed by different mechanisms; it is conceivable that the oxidation occurs by way
of the attack of ·OH species produced from the V species in the zeolite framework with H2O2. 相似文献
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D. Živković M. Sokić Ž. Živković D. Manasijević Lj. Balanović N. Štrbac V. Ćosović B. Boyanov 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1173-1176
The results of thermal study and mechanism of the oxidation process of synthetic Ag2S in air are presented in this article based on the comparative analysis of DTA and XRD results, as well as by constructed phase stability diagrams (PSD) for the Ag–S–O system. 相似文献
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The thermal and photochemical reactions between CrO2Cl2 and H2S have been investigated using matrix isolation infrared spectroscopy. Twin-jet co-deposition of the two reagents into argon matrices at 14 K followed by irradiation with light of lambda > 300 nm led to the growth of a number of new bands. These have been assigned to the HSOH-CrCl2O complex, and to SO2. These assignments were supported by deuterium isotopic substitution and high level density functional calculations. Merged-jet deposition with the reaction zone at temperatures above 125 degrees C led to substantial yields of SO2 and HCl, as well as the complex of HCl with excess parent H2S. The evidence suggests that the thermal and photochemical reactions may follow different pathways. 相似文献
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Paola Antoniotti Lorenza Operti Roberto Rabezzana Francesca Turco Gian Angelo Vaglio Felice Grandinetti 《Journal of mass spectrometry : JMS》2009,44(5):725-734
The gas phase ion chemistry of silane/hydrogen sulfide and germane/hydrogen sulfide mixtures was studied by ion trap mass spectrometry (ITMS), in both positive and negative ionization mode. In positive ionization, formation of X/S (X = Si, Ge) mixed ions mainly takes place via reactions of silane or germane ions with H2S, through condensation followed by dehydrogenation. This is particularly evident in the system with silane. On the other side, reactions of HnS2+ ions with XH4 (X = Si, Ge) invariably lead to formation of a single X? S bond. In negative ionization, a more limited number of mixed ion species is detected, but their overall abundance reaches appreciable values, especially in the SiH4/H2S system. Present results clearly indicate that ion processes play an important role in formation and growth of clusters eventually leading to deposition of amorphous solids in chemical vapor deposition (CVD) processes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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以乙酰二茂铁和蒽醛为原料,合成了一种新的反应型荧光探针1-二茂铁基-3-(9-蒽基)丙烯酮,经1H NM R,13C NM R,IR,LC-M S等手段表征确证。基于Michael加成引起的电子转移机制,利用硫化氢的强亲核性,以荧光滴定法考察了该化合物在生理条件下对硫化氢的识别作用,得出其最佳识别时间为50 min,最佳识别浓度为50μmol/L,且多数离子不会对其识别作用产生干扰。这种能稳定检测的,具有高选择性、高灵敏度的反应型荧光探针化合物,可用于生物医药领域。 相似文献
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Quantum chemical methods at the Gaussian-2 and -3 levels of theory have been used to investigate the reactions between H(2)S, SO(2), and S(2)O such as might occur in the front-end furnace of the Claus process. The direct reaction between H(2)S and SO(2) occurs via a 5-centered transition state with an initial barrier of approximately 135 kJ mol(-1) and an overall barrier of approximately 153 kJ mol(-1) to produce S(2)O and H(2)O. We indicate approximate values here because there are a number of isomers in the reaction pathway that have barriers slightly different from those quoted. The presence of a water molecule lowers this by approximately 60 kJ mol(-1), but the van der Waals complex required for catalysis by water is thermodynamically unfavorable under the conditions in the Claus reactor. The direct reaction between H(2)S and S(2)O can occur via two possible pathways; the analogous reaction to H(2)S + SO(2) has an initial barrier of approximately 117 kJ mol(-1) and an overall barrier of approximately 126 kJ mol(-1) producing S(3) and H(2)O, and a pathway with a 6-centred transition state has a barrier of approximately 111 kJ mol(-1), producing HSSSOH. Rate constants, including a QRRK analysis of intermediate stabilization, are reported for the kinetic scheme proposed here. 相似文献
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Yi‐Zhen Tang Hao Sun Ya‐Ru Pan Xiu‐Mei Pan Rong‐Shun Wang 《International journal of quantum chemistry》2007,107(9):1907-1914
The mechanisms for the reaction of C2H5S with NO2 are investigated at the QCISD(T)/6‐311++G(d, p)//B3LYP/6‐311++G(d, p) level on both single and triple potential energy surfaces. The geometries, vibrational frequencies and zero‐point energy (ZPE) corrections of all stationary points involved in the title reaction are calculated at the B3LYP/6‐311++G(d, p) level. The results show that the reaction is more predominant on the single potential energy surface, while it is negligible on the triple potential energy surface. Without barrier height in the whole process, the major channel is R → C2H5SONO (IM1 and IM2) → P1 (C2H5SO+NO). With much heat released in the formation of C2H5SNO2 (IM3) and the transition state involved in the subsequent step more stable than reactants, P4 (CH3CHS + t‐HONO) is subdominant product energetically. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
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Lomello-Tafin M Chaou AA Morfin F Caps V Rousset JL 《Chemical communications (Cambridge, England)》2005,(3):388-390
The intimate mixture of a skeletal gold structure with ZrO2 nanoparticles obtained simply by oxidation of Au(0.5)Zr(0.5) alloy at room temperature turns out to be an efficient catalyst for the selective oxidation of CO in the presence of hydrogen. 相似文献
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CH3S自由基H迁移异构化及脱H2反应的直接动力学研究 总被引:5,自引:0,他引:5
采用密度泛函方法(MPW1PW91)在6.311G(d,p)基组水平上研究了CH3S自由基H迁移反应CH3S→CH2SH(R1),脱H2反应CH3S→HCS+H2(R2)以及脱H2产物HCS异构化反应HCS→CSH(R3)的微观动力学机理.在QCISD(t)/6.311++G(d,p)//MPW1PW91/6.311G(d,p)+ZPE水平上进行了单点能校正.利用经典过渡态理论(TST)与变分过渡态理论(CVT)分别计算了各反应在200-2000K温度区间内的速率常数K^TST和k^CVT,同时获得了经小曲率隧道效应模型(SCT)校正后的速率常数萨k^CVT/SCT.结果表明,反应R1,R2和R3的势垒△E^≠分别为160.69,266.61和241.63kJ/mol。R1为反应的主通道.低温下CH3S比CH2SH稳定,高温时CH2SH比CH3S更稳定.另外,速率常数计算结果显示,量子力学隧道效应在低温段对速率常数的计算有显著影响,而变分效应在计算温度段内对速率常数的影响可以忽略. 相似文献
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《Tetrahedron: Asymmetry》2007,18(16):1975-1980
l-Proline catalyzed direct diastereoselective aldol reactions of α-amino aldehydes with cyclic ketones have been described and utilized further for the stereoselective synthesis of the 2-amino-1,3,4-triol unit as the phytosphingosines base backbone. This leads to the formal synthesis of (2S,3S,4S)-lyxo-phytosphingosine. 相似文献
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Marta León José Jiménez-Jiménez Antonio Jiménez-López Enrique Rodríguez-Castellón Dolores Soriano José M. López Nieto 《Solid State Sciences》2010,12(6):996-1001
Vanadium oxide–containing mesoporous materials, based on a surfactant expanded zirconium phosphate with silica galleries into the interlayer space, named porous phosphate heterostructure (PPH), were prepared by using TEOS and vanadium oxytripropoxide in n-propanol as sources of Si and V, respectively; with different Si/V molar ratios of 1, 2, 5 and 25; and calcining at 550 °C for 6 h. Using this method, vanadium can be partially incorporated to the structure of the gallery, but the surface area strongly decreases and the appearance of V2O5 crystallites increases when increasing the vanadium content. The catalysts were characterized by XRD, XPS, TEM, and Raman, and tested in the selective catalytic oxidation of H2S using a fixed bed reactor, at atmospheric pressure, at 180–260 °C. The catalysts with high contents of vanadium are very active at 200 °C, showing H2S conversions of 85–99%, with a high selectivity to elemental sulphur and with a low formation of SO2. Accordingly V2O5 crystallites can be proposed as active and selective although the catalytic behavior is related to the number of accessible V-sites in the surface of the catalyst. 相似文献
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Andrzej Leś 《Theoretical chemistry accounts》1985,66(6):375-393
Intermolecular potential energy curves for the hydrogen bonded systems H2O·H2S, H2O·H2Se and H2S·H2S were calculated with nonempirical pseudopotentials using optimized-in-molecules basis sets augmented by polarization functions. The H2O·H2O interaction energy curve has been also considered as a test case. The present results for H2O·H2S and H2S·H2S indicate much weaker intermolecular interactions than those found in previous ab initio calculations. The H2O·H2Se interaction was found to be quite similar to H2O·H2S.This work was partly supported by the Polish Academy of Sciences within the Project PAN-09, 7.1.1.1On leave from Quantum Chemistry Laboratory, Dept. of Chemistry, University of Warsaw, Pasteura 1, 02-093. Warsaw, Poland 相似文献