低热固相反应的反应机理研究(1)--冷融熔机理和冷溶熔机理的模型

本文提出了低热固相反应的冷融熔机理和冷溶熔机理,其中冷融熔机理主要针对于不含结晶水的反应体系,冷溶熔机理主要针对于含结晶水的反应体系,并对低热固相反应动力学提出冷融熔/冷溶熔、扩散、反应、成核、生长的五步机理.两种机理都避开了分子在固相晶格中的扩散,从而对低热固相反应的扩散问题进行了有效的解释,并给出了低热固相反应的热力学和动力学判据.     

低热固相反应的反应机理研究(Ⅰ)——冷融熔机理和冷溶熔机理的模型

本文提出了低热固相反应的冷融熔机理和冷溶熔机理,其中冷融熔机理主要针对于不含结晶水的反应体系,冷溶熔机理主要针对于含结晶水的反应体系,并对低热固相反应动力学提出冷融熔/冷溶熔、扩散、反应、成核、生长的五步机理。两种机理都避开了分子在固相晶格中的扩散,从而对低热固相反应的扩散问题进行了有效的解释,并给出了低热固相反应的热力学和动力学判据。     

Mechanism of the molecular hysteresis

The redox behavior in acetone solution of (1,5-dithiacyclooctane 1-oxide)bis(pentaammineruthenium(II)) has been characterized, where the concept of “molecular hysteresis” is presented. Detailed thermodynamics for the complex are studied, in which intramolecular electron transfer rates for Ru³⁺OS/Ru²⁺→Ru²⁺SO/Ru³⁺ were determined as 0.12 sec^?1 and 0.055 sec^?1. The molecular hysteresis consists of two important factors: isomerizations for the sulfoxideruthenium complexes and the slow intramolecular electron transfer in the complex; both are examined. Isomerization rates for Ru³⁺S→O and Ru²⁺O→S determined range from 0.4 to 5000 sec^?1 and from 0.7 to 16 sec^?1, respectively, for [Ru(NH₃)₅(sulfoxide)]^2+/3+. A mechanism for the slow electron transfer in the complex is also presented. Features of molecular hysteresis are discussed.     

Mechanism of the heterodiene synthesis

The kinetics of the reaction of diethyl azodicarbonate with various oxazoles were studied, and a model of the activated complex with partial separation of the charges of opposite sign is proposed. The results of the calculations, which were made via the Hückel MO method, are in good agreement with the two-step mechanism of the heterodiene synthesis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 600–607, May, 1973.The authors thank A. S. Ol'khovyi and V. G. Tumanyan for their assistance in performing the calculations.     

F＋Cl2->ClF＋Cl和Cl′F＋Cl->Cl′＋ClF的反应机理

用密度泛函理论(DFT)B3LYP方法,取6 311G基组,计算研究了F＋Cl2ClF＋Cl的反应机理.求得1个线形和2个三角形过渡态,反应能垒分别为1.24、46.37和105.09kJ•mol－1;同时发现F以∠FClCl为10～20°（或 120～160°）进攻Cl2时,反应无能垒.此外,求得对称反应Cl′F＋ClCl′＋ClF的能垒为40.57 kJ•mol－1的1个过渡态.     

Mechanism of the clay-kinnear-perren condensation

Several apparently unrelated aspects of the process whereby complexes of the type [RPCl₃]⁺[Al Cl₄]⁻ are formed from phosphorus trichloride, aluminium chloride and an alkyl halide, are shown to be compatible in terms of a mechanism involving preliminary formation of a carbonium cation.     

二氟硅杂环丙烯异构化反应的理论研究

近十几年来，硅烯（：SN小'一到作为活性中间体的研究引起化学界的广泛兴趣，形成了内容丰富的硅烯化学．1975年Ilass＊等研究了硅烯和乙炔的加成反应，指出该反应的中间体为硅杂环丙烯，硅杂环丙烯异构化为硅甲基乙炔．Boatz问等利用：j－ZIG（d）基组对金属杂环丙烯小［＊xZC     

硅杂环丙烯异构化反应的理论研究

用量子化学理论方法研究了硅杂环丙烯单重态的异构化反应。结果表明:该异构化反应的过渡态为三元环结构,该反应为氢迁移反应;反应的势垒高度为276.67kJ·mol^-^1[MP2/6-31G(d)]。通过内禀反应坐标(IRC)计算,获得了沿反应途径的势能剖面。     

Mechanism of the combustion of methane

Conclusions The proposed mechanism of the combustion of methane satisfactorily describes the experimental material on the kinetics of atomic flames.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2191–2196, October, 1971.The authors would like to express their gratitude to A. Ya. Dubovitskii under whose supervision the program was compiled for the electronic computer.     

Mechanism of the hydrolysis of N-aryliminotriphenylphosphoranes

Hydrolysis reactions of N-aryliminotriphenylphosphoranes (I) at varying pH have been investigated kinetically. The reactions produced aniline derivatives and triphenylphosphine oxide as the products. The reactions are first-order, and the Hammett values are -0.29 and -0.63 at pH 3.0 and 8.0, respectively. The reaction rate increased linearly with acetate ion concentration at [AcO^–] < 0.05 M and approached a limiting value at higher base concentration. The plot of logk _t versus pH shows that there are two different regions in the rate profile; one part in which logk _t increases with hydronium ion concentration and the other where k _t is a constant regardless of pH. On the basis of these results, a plausible hydrolysis mechanism is proposed. At pH < 8.0, the reaction proceeds by protonation of the iminophosphorane nitrogen atom, followed by the addition of a water molecule. At pH > 8.0, the proton transfer from water to -nitrogen of the iminophosphorane becomes the rate limiting step.From Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 26–34.Original English Text Copyright © 2005 by Pyun, Lee, Kim.This article was submitted by the authors in English.     

Mechanism of the carbonylation of dicyclopentadienylmolybdenum dihydride

The carbonylation of Cp₂MoH₂ proceeds through the intermediates Cp₂MoCO, [Cp₂Mo(H)CO] [CpMo(CO)₃] (I) and CpMo(CO)₃ to the final products [CpMo(CO)₃]₂ and CpMo(η³-C₅H₇)(CO)₂. The formation of I in the carbonylation reaction has been shown to involve net hydride transfer, but an alternate synthesis has demonstrated the considerable proton basicity of Cp₂MoCO. Since the net hydride transfer between Cp₂MoH₂ and [CpMo(CO)₃]₂ can be accelerated by production of metal centered radicals, the actual mechanism is not a simple two-electron process (H^? transfer, but rather a sequence of one-electron steps.