热动力学的滴定量热法研究 Ⅰ.一级反应的热动力学

用滴定量热法分别建立了满定期和停满反应期一级反应热动力学的数学模型．根据这两种模型，均可由一次实验的滴定量热曲线同时解析出一级反应的速率常数（k1）和摩尔反应治（△rHm）．用液定量热法研究了去离子水溶剂中乙酸乙酯皂化反应的热动力学，实验结果验证了本文用滴定量热法研究一级反应热动力学的运用性．     

热动力学的滴定量热发研究 I.一级反应的热动力学

用滴定量热法分别建立了滴定期和滴反应期一级反应热动力学的数学模型，根据这两种模型，均可由一次实验的滴定量热曲线同时解析出一级反应的速率常数和摩尔反应焓。用滴定量热法研究了去离子水溶剂中乙酸乙酯皂化反应的热动力学，实验结果验证了本文用滴定量热法研究一级反应热动力学的适用性。     

热动力学的滴定量热法研究2: 单底物酶促反应的热动力学

用滴定量热法分别建立了滴定期和停滴反应期单底物酶促反应热动力学的数学模型。根据这两种模型,可由一次实验的滴定量热曲线同时解析出单底物酶促反应的热力学参数(Δ~rH~m)和动力学参数(K~m和k~2)。用滴定量热法研究了一个经典的单底物酶促反应---过氧化氢酶催化分解过氧化氢反应的热动力学,由滴定期和停滴反应期热动力学模型解析出在298.15K和pH=7.0时该反应的米氏常数K~m分别为(5.41±0.24)×10^-^3和(5.43±0.21)×10^-^3mol.L^-^1,酶转换数k~2分别为(3.58±0.33)×10^3和(3.60±0.41)×10^3s^-^1,摩尔反应焓为(-86.75±0.88)kJ.mol^-^1,实验结果验证了上述热动力学模型的正确性。     

热动力学的滴定量热法研究2: 单底物酶促反应的热动力学

用滴定量热法分别建立了滴定期和停滴反应期单底物酶促反应热动力学的数学模型。根据这两种模型,可由一次实验的滴定量热曲线同时解析出单底物酶促反应的热力学参数(Δ~rH~m)和动力学参数(K~m和k~2)。用滴定量热法研究了一个经典的单底物酶促反应---过氧化氢酶催化分解过氧化氢反应的热动力学,由滴定期和停滴反应期热动力学模型解析出在298.15K和pH=7.0时该反应的米氏常数K~m分别为(5.41±0.24)×10^-^3和(5.43±0.21)×10^-^3mol.L^-^1,酶转换数k~2分别为(3.58±0.33)×10^3和(3.60±0.41)×10^3s^-^1,摩尔反应焓为(-86.75±0.88)kJ.mol^-^1,实验结果验证了上述热动力学模型的正确性。     

层状钙钛矿化合物 (n-CnH2n+1NH3)2ZnCl4非等温固-固相变动力学的确定

确定了具有层状钙钛矿结构,脂肪链C原子数从12到18四氯合锌酸二烷基铵(C_nH_2n+1NH₃)₂ZnCl₄系列化合物的非等温固-固相变动力学。采用Kissinger和Ozawa两种动力学模型,对不同温度下测定的每个样品DSC热分析曲线进行数据处理,计算固-固相变过程的活化能E_a。实验结果表明,随着C原子数的增加,脂肪链的有序度和刚度降低,导致固-固相变活化能E_a随C原子数的增大而降低。两种模型方法的计算活化能E_a的结果相一致。并且各个化合物的固-固相变反应级数不随升温速率和烷基链长变化而变化,总保持为1。     

一维链状配位聚合物{[Cu(H2bttc)(H2O)3]·3H2O}n的非等温反应动力学和晶体结构

为研究配位聚合物{[Cu(H₂bttc)(H₂O)₃]·3H₂O}_n(H₂bttc=1，2，4，5-benzenetetracarboxylate)的热分解机理和非等温反应动力学进行了DSC和TG-DTG热分析。由热分析结果和FTIR光谱推测了其热分解机理；将Kissinger法、Ozawa法、积分法和微分法得到的动力学参数进行比较确定了第一个失重过程最可能的动力学模型函数。配位聚合物的X射线单晶结构分析表明它由 [Cu(H₂bttc)(H₂O)₃]_n分子链组成，并有客体水分子通过分子间氢键附着在分子链上。这一结构特点与热分析结果相一致。还有一种氢键将分子链连接起来形成二维框架，这一框架在失去配位水和结晶水后到553 K开始分解。     

生物柴油替代混合物化学动力学模型构建及路径分析

以癸酸甲酯(C₁₁H₂₂O₂)和正庚烷(nC₇H₁₆)作为生物柴油替代混合物,通过相对分子质量、低热值以及含氧量与实际生物柴油对比确定两种组分按摩尔比1：1混合,并在此基础上构建了一个由691种组分、3226个基元反应组成的生物柴油替代混合物的化学动力学机理. 在激波管条件下该机理计算的着火延迟与实验数据吻合很好;在发动机条件下该机理计算的缸内压力与实验值吻合很好,CO、未燃碳氢和NOx与实验结果趋势一致.此外,本文还对替代混合物的低温反应动力学过程进行了分析,结果表明癸酸甲酯脱氢产物主要为MD2J和MDMJ. MD2J在低温阶段的主要消耗途径除了加氧之外,还有与正庚烷基(C₇H₁₅-1)第一次加氧产物(C₇H₁₅O₂-3)进行交叉反应;发生分解反应生成MP2D及与氧发生脱氢反应生成MD2D. 另一种主要脱氢产物MDMJ在低温阶段的主要消耗途径为通过同分异构转化为MD2J和MD3J.     

铀(Ⅵ)与不对称希夫碱配合物的合成和热分解反应动力学

邻苯二胺与5－氯－2－羟基二苯酮、邻香草醛作用合成了一种不对称希夫碱配体C₂₇H₂₁N₂O₃Cl（H₂L）。在正丁醇和甲醇体系中硝酸铀酰与该配体反应合成了一种固体希夫碱配合物[UO₂(HL)(NO₃)(H₂O)]·H₂O。通过元素分析、IR、UV、¹H NMR、TG-DTG及摩尔电导率分析等手段对合成的配合物进行了表征,用非等温热重法研究了铀(Ⅵ)配合物的热分解反应动力学,推断出第三步热分解的动力学方程为：d α /d t = A · e^{- E/RT} ·3/2[(1- α )^-1/3-1]^-1,得到了动力学参数E和A。并计算出了活化熵△S^¹和活化吉布斯自由能△G^¹。     

CH3OCF2CF2OCH3+Cl的反应机理及动力学性质

利用密度泛函理论直接动力学方法研究了反应CH₃OCF₂CF₂OCH₃+Cl的微观机理和动力学性质. 在BB1K/6-31+G(d,p)水平上获得了反应的势能面信息, 计算中考虑了反应物CH₃OCF₂CF₂OCH₃两个稳定构象(SC1和SC2)的氢提取通道和取代反应通道. 利用改进的正则变分过渡态理论结合小曲率隧道效应(ICVT/SCT)计算了各氢提取通道的速率常数, 进而根据Boltzmann配分函数得到总包反应速率常数(k_T)以及每个构象对总反应的贡献. 结果表明296 K温度下计算的k_T(ICVT/SCT)值与已有实验值符合得很好. 由于缺乏其他温度速率常数的实验数据, 我们预测了该反应在200-2000 K温度区间内反应速率常数的三参数表达式: k_T=0.40×10^-14T^1.05exp(-206.16/T).     

人血清白蛋白与季铵盐双子表面活性剂的相互作用

在298.15 K下, 应用等温滴定量热法研究了人血清白蛋白(HSA)与两种季铵盐双子表面活性剂[(C_nN)₂Cl₂, n＝12, 14]在缓冲溶液(pH＝7.0)中相互作用的热力学性质. 实验结果表明, HSA对这两种表面活性剂有两类结合位点, 分别为结合时需要吸收热量的强结合位点和可放出热量的弱结合位点. 两种表面活性剂对应的第一类结合——强结合为熵驱动过程, 且该结合位点对应的结合位点数、结合常数和热力学参数差别不大. 至于第二类结合——弱结合位点, 由于 (C₁₄N)₂Cl₂ 疏水链过长, 只有部分进入HSA的疏水空腔内, 因此相应的的结合位点数和放热量减小, 而熵变增加, 为焓和熵共同驱动的反应. 圆二色研究表明(C_nN)₂Cl₂的加入使HSA的二级结构发生变化, 这说明(C_nN)₂Cl₂与HSA的相互作用既包含结合反应也包含(C_nN)₂Cl₂诱导该蛋白部分结构改变的过程.     

聚二烯丙基二甲基氯化铵在质子交换膜表面静电自组装过程的热力学研究

本文通过热化学方法设计了PDDA滴定质子交换膜,并研究了高分子的静电自组装过程。通过非线性拟合数据分析,求出了自组装过程的焓变（ ）和结合常数（K）。根据该反应过程中的热力学参数,可知自组装过程是“焓驱动”反应。热量的放出代表着能量的降低,有利于反应的发生;而自由度的减小不利于反应的发生。对于每个离子键的形成,单分子DDA的焓变超过了PDDA,这是因为小分子能够更加自由地结合到膜上,而高分子PDDA有一定的位阻效应。     

Kinetics and mechanism study of aniline addition to ethyl propiolate

The kinetics of the addition reaction of aniline to ethyl propiolate in dimethylsulfoxide (DMSO) as solvent was studied. Initial rate method was used to determine the order of the reaction with respect to the reactants, and pseudo‐first‐order method was used to calculate the rate constant. This reaction was monitored by UV–Vis spectrophotometer at 399 nm by the variable time method. On the basis of the experimental results, the Arrhenius equation for this reaction was obtained as log k = 6.07 ‐ (12.96/2.303 RT). The activation parameters, E_a, ΔH^#, ΔG^#, and ΔS^# at 300 K were 12.96, 13.55, 23.31 kcal mol^?1 and ?32.76 cal mol^?1 K^?1, respectively. The results revealed a first‐order reaction with respect to both aniline and ethyl propiolate. In addition, based on the experimental results and using also density functional theory (DFT) at B3LYP/6‐31G* level, a mechanism for this reaction was proposed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 144–151, 2006     

Theoretical investigation on the photophysical properties of N‐heterocyclic carbene iridium (III) complexes (fpmb)xIr(bptz)3‐x (x = 1−2)

In the search for efficiently phosphorescent materials, this article presents a rational design and theoretical comparative study of some photophysical properties in the (fpmb)_xIr(bptz)_3‐x (x = 1–2), which involve the usage of two 2‐pyridyl triazolate ( bptz ) chromophores and a strong‐field ligand fpmb ( fpmb = 1‐(4‐difluorobenzyl)‐3‐methylbenzimidazolium). The first principle theoretical analysis under the framework of the time‐dependent density functional theory approach is implemented in this article to investigate the electronic structures, absorption and phosphorescence spectra. It is intriguing to note that 1 and 2 exhibit theirs blue phosphorescent emissions with maxima at 504 and 516 nm, respectively. Furthermore, to obtain the mechanism of low phosphorescence yield in 1 and estimate the radiative rate constant k_r for 2 , we approximately measure the radiative rate constant k_r, the spin‐orbital coupling (SOC) value, ΔE (S ? T), and the square of the SOC matrix element (<Ψ_S1.H_SO.Ψ_T1>²) for 1 and 2 . Finally, we tentatively come to conclusion that the switch of the cyclometalated ligand from the main to ancillary chelate seems to lower the splitting ΔE (S ? T) in the current system. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012     

Ab initio study of reactions of hydroxyl radicals with chloro‐ and fluoro‐substituted methanes

Ab initio calculations at the unrestricted Hartree–Fock (UHF) level have been performed to investigate the hydrogen abstraction reactions of ^? OH radicals with methane and nine halogen‐substituted methanes (F, Cl). Geometry optimization and vibrational frequency calculations have been performed on all reactants, adducts, products, and transition states at the UHF/6‐31G* level. Single‐point energy calculations at the MP2/6‐31++G* level using the UHF/6‐31G* optimized geometries have also been carried out on all species. Pre‐ and postreaction adducts have been detected on the UHF/6‐31G* potential energy surfaces of the studied reactions. Energy barriers, ΔE^?, reaction energies, ΔE_r, reaction enthalpies, ΔH_r, and activation energies, E_a, have been determined for all reactions and corrected for zero‐point energy effects. Both E_a and ΔH_r come into reasonable agreement with the experiment when correlation energy is taken into account and when more polarized and diffuse basis sets are used. The E_a values, estimated at the PMP2/6‐31++G* level, are found to be in good agreement with the experimental ones and correctly reproduce the experimentally observed trends in fluorine and chlorine substitution effects. A linear correlation between E_a and ΔH_r is obtained, suggesting the presence of an Evans–Polanyi type of relationship. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 426–440, 2001     

Kinetic Study of Complex Formation of by 2‐Nitroso‐1‐naphthol with Cobalt (II) Ion in Presence of Cetyltrimethylammonium Bromide Surfactant

The kinetic complex formation of 0.001 M 2‐nitroso‐1‐naphthol (NAPH)with 0.01 M cobalt (II) ion (Co²⁺) in aqueous in presence of 0.02 M NaOH at 30°C in aqueous and/or in and 0.002 M cetyltrimethylammonium bromide (CTAB) have been studied using spectrophotometer at 430 nm. The present data showed that the reaction is first‐order with respect to [Co²⁺]_T and NAPH. Also, k _obs have constant values within concentration 0.015–0.05 M of NaOH and decreases with increase of concentration of CTAB to 0.002 M, then, k _obs have constant values up to 0.005 M. The rate of the reaction in the presence of micelles has been explained with the pseudo‐phase model of the kinetics. Association constants of Co²⁺ and NAPH to CTAB micelle have been calculated. The activation parameters ΔH* and ΔS* have been obtained. The increase of reaction rate with sodium benzoate (C₇H₅O₂Na) also has been discussed.     

Ag(I)‐Catalyzed Chlorination of Linezolid during Water Treatment: Kinetics and Mechanism

The kinetic and mechanistic study of Ag(I)‐catalyzed chlorination of linezolid (LNZ) by free available chlorine (FAC) was investigated at environmentally relevant pH 4.0–9.0. Apparent second‐order rate constants decreased with an increase in pH of the reaction mixture. The apparent second‐order rate constant for uncatalyzed reaction, e.g., k″_app = 8.15 dm³ mol⁻¹ s⁻¹ at pH 4.0 and k″_app. = 0.076 dm³ mol⁻¹ s⁻¹ at pH 9.0 and 25 ± 0.2°C and for Ag(I) catalyzed reaction total apparent second‐order rate constant, e.g., k″_app = 51.50 dm³ mol⁻¹ s⁻¹ at pH 4.0 and k″_app. = 1.03 dm³ mol⁻¹ s⁻¹ at pH 9.0 and 25 ± 0.2°C. The Ag(I) catalyst accelerates the reaction of LNZ with FAC by 10‐fold. A mechanism involving electrophilic halogenation has been proposed based on the kinetic data and LC/ESI/MS spectra. The influence of temperature on the rate of reaction was studied; the rate constants were found to increase with an increase in temperature. The thermodynamic activation parameters E_a, ΔH^#, ΔS^#, and ΔG^# were evaluated for the reaction and discussed. The influence of catalyst, initially added product, dielectric constant, and ionic strength on the rate of reaction was also investigated. The monochlorinated substituted product along with degraded one was formed by the reaction of LNZ with FAC.     

Kinetic and thermodynamic analysis of degradation of doripenem in the solid state

The kinetic and thermodynamic parameters of degradation of doripenem were studied using a high‐performance liquid chromatography method. In dry air, the degradation of doripenem was a first‐order reaction depending on the substrate concentration. At increased relative air humidity, doripenem was degraded according to the autocatalysis kinetic model. The dependence ln k = f1/T) was described by the equations ln k = 5.10 ± 13.06 ? (7576 ± 4939)(1/T) in dry air and ln k = 46.70 ± 22.44 ? (19,959 ± 8031)(1/T) at 76.4% relative humidity (RH). The thermodynamic parameters E_a, ΔH^≠a, and ΔS^≠a of the degradation of doripenem were calculated. The dependence ln k = f (RH%) was described by the equation ln k = (0.155 ± 0.077) × 10^?1 (RH%) ? (3.45 ± 21.8) × 10^?10. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 722–728, 2012     

Kinetic and mechanistic significance of the chemical activation of ciprofloxacin for conjugation chemistry

Ciprofloxacin is an important category of fluroquinolones that has versatile applications in imaging when conjugated with different ligands. For conjugation chemistry, chemical activation of the carboxylic group at the third position is an important step. Here, we study the kinetics for the activation of the acidic group of ciprofloxacin by N‐hydroxysuccinimide (NHS) and dicyclohexylcarbodiimide (DCC). The extent of the reaction was followed by registering a decrease in absorbance at 332, 412, and 423 nm by monitoring the consumption of ciprofloxacin as a function of [NHS], [DCC], pH, ionic strength, and temperature by varying only one parameter at a time while keeping all other parameters constant. The reaction between ciprofloxacin and NHS, in the presence of DCC, exhibits a 1:1:1 stoichiometry. The reaction is found to show first‐order dependence on the concentration of ciprofloxacin to the order of 10³ s^?1(k_obs) and zero order with respect to the concentrations of NHS and DCC, respectively. The activation parameters and thermodynamic quantities vis‐à‐vis E_a, ΔH^≠, and ΔS^≠ have been computed with respect to the forward reaction as 12.024, 131.43, and 27.31 J K^?1 mol^?1, respectively, which provided additional support to the proposed kinetic pathway. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 349–356, 2009     

Kinetic and Mechanistic Insights into the Pathway Leading to Cyclic Crystalline Phosphorus Ylide Formation in the Presence of 3‐Chloropentane‐2,4‐dione: Theoretical and Stopped‐Flow Approaches

In this work, three speculative mechanisms of the reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of 3‐chloropentane‐2,4‐dione were energetically and thermodynamically developed using quantum mechanical calculations and were profoundly compared with stopped‐flow and UV spectrophotometry approaches. The third speculative mechanism that led to the five‐membered ring structure was experimentally and theoretically favorable. The five‐membered ring structure of product was characterized by X‐ray crystallographic data. Also, steps 1 and 2 of the third mechanism were determined as fast and rate‐determining steps, respectively. The experimental kinetic evidence of the formation and decay of intermediate in steps 1 and 2 (fast and rate‐determining steps, respectively) was compatible with theoretical data. Experimental kinetic data were recognized for overall reaction along with activation parameters for fast and rate‐determining steps of the reaction. Theoretical kinetic data (k and E_a) and activation parameters (ΔG^≠, ΔS,^≠ and ΔH^≠) were calculated for each step and overall reactions.     

1，1－二氨基2，2－二硝基乙烯（DADE）的热化学性质、热行为和热分解机理

The constant-volume combustion energy, △cU （DADE, s, 298.15 K）, the thermal behavior, and kinetics and mechanism of the exothermic decomposition reaction of 1,1-diamino-2,2-dinitroethylene （DADE） have been investigated by a precise rotating bomb calorimeter, TG-DTG, DSC, rapid-scan fourier transform infrared （RSFT-IR） spectroscopy and T-jump/FTIR, respectively. The value of △cHm （DADE, s, 298.15 K） was determined as （-8518.09±4.59） j·g^-1. Its standard enthalpy of combustion, △cU （DADE, s, 298.15 K）, and standard enthalpy of formation, △fHm （DADE, s, 298.15 K） were calculated to be （-1254.00±0.68） and （- 103.98±0.73） kJ·mol^-1, respectively The kinetic parameters （the apparent activation energy Ea and pre-exponential factor A） of the first exothermic decomposition reaction in a temperature-programmed mode obtained by Kissinger＇s method and Ozawa＇s method, were Ek=344.35 kJ·mol^-1, AR= 1034.50 S^-1 and Eo=335.32 kJ·mol^-1, respectively. The critical temperatures of thermal explosion of DADE were 206.98 and 207.08 ℃ by different methods. Information was obtained on its thermolysis detected by RSFT-IR and T-jump/FTIR.