可逆反应的热静力学研究法

本文建立了一种新的可逆反应的热静力学研究方法, 并利用本法研究了18-冠-6与钾离子、钡离子在水中的配位反应。实验测得的这两种反应的平衡常数和焓变与文献值很好吻合。本法适用于平衡常数大于1而小于10^4的反应体系。     

可逆反应的热动力学研究——数学模型和研究法

本文根据热动力学的理论和方法,建立了二种可逆反应动力学的数学模型和研究方法,并通过氨与硝基乙烷的2-2型和准1-1型可逆反应的热动力学加以验证。     

化学反应的热动力学研究法进展

本文综述了近年基于Ｔｉａｎ方程建立的化学反应热动力学研究法的进展。重点评述了无量纲参教法、对比进度法、模拟热谱曲线法,特征参量法和时间变量法。     

热动力学对比进度法 I. 可逆反应热动力学模型

引入“对比进度”的概念, 建立了可逆反应动力学新的数学模型, 提出了可逆反应动力学的对比进度研究法. 并用热导式自动热量计研究了一个可逆反应体系, 计算结果与文献值符合甚好, 验证了数学模型及对比进度法的正确性.     

平行反应的热动力学研究法

根据热动力学基本理论, 推导了平行准一级反应和平行准一二级反应的热动力学方程, 建立了热谱解析平行反应动力学参数的热动力学研究法, 并利用该法研究了两个模拟平行反应体系的热动力学, 实验结果验证了方法的正确性.     

绝热式热动力学的研究4: 可逆反应的热谱解析

本文建立了可逆反应在绝热系统中的热动力学研究法, 并用自制的绝热式自动热量计, 研究了三个可逆反应体系的热动力学, 验证了本文方法的正确性。     

绝热式热动力学的研究：Ⅳ.可逆反应的热谱解析

本文建立了可逆反应在绝热系统中的热动力学研究法，并用自制的绝热式自动热量计，研究了三个可逆反应体系的热动力学，验证了本文方法的正确性。     

较快一级化学反应的热动力学研究法: 热弛豫法

分析了非稳态传热情况下热导式热量计的动态性能,通过对输出信号的剖析,建立了热导式热量计冷却常数的经验动态模型。通过对热弛豫现象的分析,建立了可用于研究快速化学反应的热动力学研究法-热弛豫法,应用此种量热研究法可用于研究速率常数小于5s^-^1的一级化学反应。研究了25℃下乙酸甲酯、甲酸乙酯和甲酸甲酯在水溶液中的皂化反应,其计算结果与文献值相吻合,从而验证了热弛豫法的正确性。     

模拟热谱曲线法（Ⅲ）——可逆反应

可逆反应是一类重要的复合反应，建立其相应的热动力学研究法有重要意义．刘劲松等[1]建立了可逆反应热动力学的对比进度研究法，曾宪诚等[2]建立了二种可逆反应热动力学无量纲参数研究法．本文根据热动力学理论和文献[3]的基本原理，建立了热导式量热体系的几类（2－2型、2－1型、1－2型）可逆反应通用的模拟热谱曲线研究法．该法无需标定热动力学体系的冷却常数，直接从一张热谱图上同时解析出可逆反应的kf、kb、K，方法更为简便，实用性强，在化学、生化反应的热动力学研究中具有广泛的应用前景．应用该法在15℃、25℃下研究了硝基乙烷…     

REVERSIBLE SKELETAL SUBSTITUTION REACTIONS INVOLVING GROUP 13 HETEROPHOSPHAZENES

An unusual, reversible skeletal substitution reaction involving boron- and aluminum-based heterophosphazenes is described.     

A GENERAL METHOD FOR THE IDENTIFICATION OF PRIMARY REACTIONS IN SENSITIZED PHOTOOXIDATIONS*

Abstract— A kinetic method for the identification of primary reactions in sensitized photooxidations is described. It is based on the calculation of Fractions of primary reactions of triplet sensitizer (³S) and singlet oxygen (¹O₂) as a function of substrate concentration (A) and on the comparison of experimental and theoretical curves. The theoretical curve that coincides with the experimental one indicates the mechanism of the chemical change observed. Only the quenching rate constants of ³S and ¹O₂ are needed for this calculation. The method enables one to distinguish the free radical and ¹O₂ mechanism. Applications of the method with 3-indole acetic acid, 1-histidine and N^-₃ using phenosafranine as the sensitizing dye (aqueous solutions, pH 7.C7.2) are described. The chemical change followed in these experiments is the bleaching of p-nitrosodimethylaniline (RNO) which gives precise and reproducible results. The bleaching of RNO is induced by the presence of some substrates which produce reactive intermediates with an oxidizing character. The kinetic method can be applied to any chemical change observed in different systems of sensitized photooxidations. The quantum yield of ³S and ¹O₂ formation need not be known.     

准1-1型对峙反应的双谱解析法

根据准１－１型对峙反应的积分动力学方程和热动力学基本理论,建立了一种新的热动力学研究法－－准１－１型对峙反应的双谱解析法。利用该法分别研究了１５℃和２５℃下硝基乙烷与氨在准１－１型条件下质子转移反应的热动力学。     

热动力学的研究(Ⅳ)——等浓度二级反应的热动力学研究法

本文根据热动力学的基础理论, 讨论了等浓度二级反应的无量纲参数法, 并用以研究了苯甲酸乙酯皂化反应的热动力学。实验测得的速度常数在误差范围内与文献值很好符合。     

氢置换反应中动力学指前因子的估算方法

本文提出了一种估算自由基－分子氢置换反应指前因子的简便方法，将指前因子归结为参加反应的两端基基因的贡献。     

TIN CHLORIN-ISOBACTERIOCHLORIN: EVIDENCE FOR A REVERSIBLE PHOTOREDOX PROCESS

Abstract— It is shown that the photoreduction of tin tetraphenylporphyrin using a variety of reducing agents does not stop at the tetraphenylchlorin stage but proceeds to the isobacteriochlorin derivative. However, this latter compound can be photooxidized in the presence of oxygen to yield exclusively tin chlorin which in turn can again be photoreduced to the isobacteriochlorin. The process appears to be photoreversible at this stage. These reactions have been studied in homogeneous and micellar solutions.     

STEADY-STATE FLUORESCENCE METHOD FOR EVALUATING EXCITED STATE PROTON REACTIONS: APPLICATION TO FLUORESCEIN

Abstract Fluorescein is a complex fluorophore in the sense that it displays four prototropic forms (cation, neutral, monoanion and dianion) in the pH range 1–9. In experiments with fluorescein-labeled proteins we have sometimes observed complex nanosecond emission kinetics, which could be due to conversion of the excited monoanion into the excited dianion through an excited state proton exchange with a proton acceptor in the labeled protein. However, the literature is ambiguous on whether this possible excited state proton reaction of fluorescein does occur in practice. In this article we describe a general steady-state fluorescence method for evaluating excited state proton reactions of simple as well as complex pH-sensitive fluorophores and apply it to evaluate excited state proton reactions of fluorescein. The method depends on finding a buffer that can serve as an excited state proton donor-acceptor but does not significantly perturb ground state proton equilibrium and especially does not form ground (or excited state complexes) with the fluorophore. Our results show that the excited monoanion-dianion proton reaction of fluorescein does occur in the presence of phosphate buffer, which serves as a proton donor-acceptor that does not significantly perturb ground state proton equilibria. The reaction becomes detectable at phosphate buffer concentrations greater than 20 mM and the reaction efficiency increases with increase in phosphate buffer concentrations. The reaction is most clearly demonstrated by adding phosphate buffer to a solution of fluorescein at constant pH 5.9 with preferential excitation of the monoanion. Under these conditions, the excited monoanion converts to the dianion during its lifetime. The conversion is detected experimentally as an increase in dianion and decrease in monoanion fluorescence intensities with increase in phosphate buffer concentration. The absorption spectrum is not significantly perturbed by the increase in phosphate buffer concentration. To quantitate the reaction, we have recorded titration graphs of fluorescence intensity versus pH for fluorescein solutions at low (5 mM) and high buffer (1 M) concentrations with preferential excitation of the monoanion and preferential detection of the dianion emission. We have also developed theoretical expressions that relate fluorescence intensity to pH in terms of the concentration of the four prototrophic forms of fluorescein, extinction coefficients, fluorescence efficiencies and ground and excited state pK_a. The theoretical expressions give very good fits to the experimental data and allow evaluation of fundamental parameters such as pK_a and fluorescence efficiencies. The analysis of the experimental data shows that the excited monoanion-dianion reaction does not significantly occur at 5 mM phosphate buffer concentration. However, at 1 M buffer concentration the reaction is sufficiently fast that it practically achieves equilibrium during the lifetimes of the excited fluorescein monoanion and dianion. The pK_a* of the excited monoanion-dianion proton reaction is around 6.3. The results and methods presented here should be useful in the development and testing of pH-sensitive labeling fluorophores and fluorescent indicators.     

预测环加成反应区域选择性的一个简易方法

长期以来,我们一直在研究化合物的性能与结构关系的定量化问题,其目的是为了寻求一个定量确定反应物反应活性的简易方法。本文研究了一种确定环加成反应区域选择性的新方法。早在七十年代初期,对于环加成反应的区域选择性问题就有报导,可以通过分子轨道法等加以确定。但是,应用分子轨道法的计算程序过于繁琐,所以应用并不广泛。1989年,S.K.Pal提出了处理这个问题的一个方程,即可以通过活性中心原有的电负性进行推算。这种原有的电负性可以用Huheey方法计算,但是这种计算方法在应用中仍然是相当复杂     

REVERSIBLE LIGHT-TNDUCED SINGLE ELECTRON TRANSFER REACTIONS BETWEEN CHLOROPHYLL AND HYDROQUINONE IN SOLUTION*

Abstract— EPR and optical studies demonstrate the occurrence of reversible temperature-independent light-induced single electron transfer reactions between chlorophyll (and pheophytin) and hydroquinone in degassed ethanol solutions. Oxygen is shown to quench this process, presumably by interacting with chlorophyll excited states. Pyridine and isoquino-line increase the effectiveness of the hydroquinone as an electron donor to chlorophyll, probably by acting as bases to form hydroquinone anions (or perhaps ion-pairs) which are more easily oxidized. Hydroquinone is found to be more effective in electron transfer than is benzoquinone, suggesting that the chlorophyll excited state is a better oxidizing agent than it is a reducing agent.     

一种合成方钠石的新方法

一种合成方钠石的新方法冯芳霞窦涛萧墉壮（太原工业大学精细化工研究所，太原０３００２４）钟炳（中国科学院山西煤炭化学研究所，太原０３０００１）关键词方钠石，正丁胺，模板剂，非水体系方钠石不仅是一种光致变材料［１，２］，而且是首先进入无机功能材料领域的...