一些简单和复杂反应动力学的Monte Carlo模拟

由于计算机的广泛应用,Monte Carlo方法作为一种独立的方法,目前已用于解决许多化学问题。但本科学生对这一重要方法还是很陌生的。另一方面,目前物理化学实验中有关动力学内容的实验,都限于简单的一级和准一级反应,对于典型的复杂反应,学生只能靠     

反应动力学通用模拟软件及其在教学中的应用

介绍了反应系统的动力学微分方程.通过使用4阶Runge-Kunta数值积分法和Visual Basic 6进行编程,得到了通用的反应动力学模拟软件,可直接计算恒温时各组分浓度随时间的变化.用于物理化学等课程的教学实践表明,软件可直观显示反应系统各组分浓度与时间和温度等影响因素的关系,有助于学生掌握反应动力学规律和课程的知识点.     

三分子反应在一维介质上的动力学行为

提出了一种简明的理论分析方法，求出了三分子反应Ａ＋２Ｘ←→３Ｘ在一维介质上的动力学行为的解析解，并成功地解决了该反应动力学行为对初始条件的依赖性问题。还通过数值模拟证实了提出了理论方法的正确性。     

N2O分解反应中复杂动力学行为的模拟

在多相催化反应中，自ZO多年前第一次在实验中观察到反应的振荡现象以来，现已发现在许多催化反应中都存在振荡现象山．N。O分解是一个振荡反应问．我们在用MonteCarloMC）方法研究N20分解反应机理时，曾发现反应速率和表面覆盖度在一定条件下都会出现振荡现象＊．非统性理论的研究表明，体系内部只要存在非线性的相互作用就可能表现出一些复杂的动力学行为，如振荡和混饨等．N。O分解反应中的振荡行为，也是由于体系内部非线性相互作用的结果·本文用非线性动力学的方法研究N。O分解反应中表面氧覆盖度的振荡行为，发现振荡在一定条…     

聚合物复杂流体流动的动力学模拟

介绍聚合物复杂流体流动问题的模拟方法。通过比较,指出了经曲有限元方法的局限性和拉格朗日－欧拉方法在模拟复杂流动问题上的优越性。拉格朗日－欧拉方法的模拟结果同聚合物流体复杂流动的实验结果相一致,表明该方法在对复杂流体的动力学行为的模拟 合理的和可行的。     

水煤气变换反应初始微观反应动力学的模拟研究

用蒙特水罗方法对水气转移反应两种典型机理的寝反应动力学进行了研究。结果表明,Ｔｅｍｋｉｎ等人的氧化－还原机理中,无论反应物ＣＯ和Ｈ２Ｏ的相对浓度怎样变化,ＣＯ２和Ｈ２的初始生成速率总是相差很大。     

微量反应系统化学动力学教学实验的设计与应用

利用光纤光谱仪构建微量反应系统,并通过偶氮染料橙黄II在铁-亚硫酸钠-溶解氧体系中的脱色反应,分别用特征动力学方程法及初始速率法进行了脱色反应动力学分析。该实验体系能够实现简单、快速的均相溶液反应动力学实验,其数据处理方法较好地巩固和提升了对反应动力学理论课教学内容的学习。整个实验体系的设计与应用能够满足物理化学、大学化学、环境化学等相关课程中有关反应动力学的实验教学需求。     

热动力学对比参量法 --简单级数反应

根据化学反应动力学和热动力学基本理论, 建立了简单级数反应的热动力学对比参量方程, 提出了一种新的热动力学研究法--对比参量法. 利用该法可以从一张热谱图上同时解析出化学反应的速率常数、半衰期和热动力学体系的冷却常数. 实验结果验证了方法的正确性.     

Photocycloaddition Reactions of Pyrazinopsoralen with Simple Olefins

Direct photolyses of pyrazinopsoralen (PzPs) with excess olefins such as dimethyl fumarate (DMFu), dimethyl maleate (DMMa) and dimethyl ethylidenemalonate (DMEM) gave C₄-photocycloadducts. The photoproducts were determined to be 1:1 C₄-cycloadducts formed through the addition of 4',5'-furan double bond of the excited P_zP_s to the olefins. The fluorescence of P_zP_s was quenched by olefins with rate constants on the order of 10₉–10₁₀ M -¹/s. The appearance of the long-lived fluorescence component implies a singlet exciplex mechanism for the photocycloaddition reaction of PzPs with excess olefins.     

Reactions of ortho-Phenylenediamine with a Nickel Trimethylacetate Complex

Interaction of ortho-phenylenediamine with the nonanuclear nickel trimethylacetate cluster Ni₉(₄-OH)₃(₃-OH)₃( _n -OOCMe₃)₁₂(HOOCCMe₃)₄(I) in an amine deficiency yields the antiferromagnetic trinuclear complex [Ni₃{-N,N"-(NH₂)₂C₆H₄}₂(HCCOOCMe₃)₃(₃-OH)(-OOCCMe₃)₄]⁺(OOCCMe₃)^–(III) containing bridging diamine ligands. Reaction of excess diamine with Ior IIIleads to the formation of the paramagnetic monomer Ni{²-o-(NH₂)₂C₆H₄}₂(OOCCMe₃)₂(IV), which reacts with atmospheric oxygen to form the known bis(semiquinonediimine) complex Ni[1,2-(NH)₂C₆H₄]₂(V).     

H+CN体系中平行络合反应的动力学

利用分子反应动力学的经典轨迹法研究化学反应体系已经开展了很多工作,但是,研究长寿命络合物的几何异构体就显得有些困难,主要表现在该方法对几何异构体不容易判别．由于这些原因和计算机时大增,Davis[1]利用经典轨迹法和统计方法相结合,研究了H＋CN和H＋NC体系在固定方位时的长寿命络合物动力学行为,并且采用Murrel等[2]拟合光谱数据的势能函数,该势能函数在HCN和HNC平衡点的频率与实验值相差较大．本文利用经典轨迹法研究了H＋CN产生HCN和HNC平行络合物异构体的分子反应动力学行为,揭示了平行络合反应产生几何异构体的…     

Glycolytic Wave Patterns in a Simple Reaction-diffusion System with Inhomogeneous Influx: Dynamic Transitions

An inhomogeneous profile of chemostatted species generates a rich variety of patterns in glycolytic waves depicted in a Selkov reaction-diffusion framework here. A key role played by diffusion amplitude and symmetry in the chemostatted species profile in dictating the fate of local spatial dynamics involving periodic, quasiperiodic, and chaotic patterns and transitions among them are investigated systematically. More importantly, various dynamic transitions, including wave propagation direction changes, are illustrated in interesting situations. Besides numerical results, our analytical formulation of the amplitude equation connecting complex Ginzburg-Landau and Lambda-omega representation shed light on the phase dynamics of the system. This systematic study of the glycolytic reaction-diffusion wave is in line with previous experimental results in open spatial reactor and will provide a knowledge about the dynamics that shape and control biological information processing and related phenomena.     

Catalytic Reactions in Heterophosphole Complex Chemistry

Catalytic reaction of 2 H -azaphosphirene complex 1 with ortho -, meta -, and para -benzodinitrile ( 2a-c ) led in all cases to the 2 H -1,4,2-diazaphosphole complexes 3a-c if ferrocenium hexafluorophosphate was used as catalyst. In the case of the meta - and para -benzodinitriles 2b-c , the bis-2 H -1,4,2-diazaphosphole complexes 4b-c were additionally obtained. Under the same reaction conditions, acetone, diethylketone and cyclohexanone ( 5a-c ) reacted with complex 1 to yield j 3 -1,3,2-oxazaphospholene complexes 6a-c in good yields.     

液滴的动态行为控制

正液滴动态行为控制在日常生活和工业生产中具有重要应用。从喷淋降温、防结冰到微流控和喷墨打印,都需要控制液滴的动态行为1,2。例如,喷淋降温过程需要延长液滴撞击到热表面后的接触时间,从而提高基底的散热量3。在干旱地区对冷凝的雾气进行收集时,需要控制液滴的定向移动4。目前,研究人员发展出各种各样的方法来控制液     

Quasi-Steady State Kinetics of Simple Sequential Multienzyme Reactions with Single Substrates

Applications of computer algebra technique to kinetic analysis of multienzyme reaction including two and three distinct enzymes were described in the literature, which mainly depend on Gröbner Basis theory. In the present study, we have applied the same methodology to a hypothetical system with four enzymes. After deriving a composite rate law for a reaction system with four distinct enzymes using the computer algebra system MAPLE, the composite rate law was fitted to simulated data for time versus product concentration to yield estimates of the kinetic parameters.     

Reactions of Fluoroalkenes with an Aluminium(I) Complex

A series of industrially relevant fluoroalkenes react with a monomeric Al^I complex. These reactions break strong sp² and sp³ C?F bonds, and result in the formation of a diverse array of organoaluminium compounds. Mechanistic studies show that two mechanisms are likely in operation: 1) direct oxidative addition of the C?F bond to Al^I occurs with retention of alkene stereochemistry, and 2) stepwise formation and decomposition of a metallocyclopropane intermediate occurs with inversion of alkene stereochemistry. As part of this mechanistic analysis, we have isolated the first aluminium metallocyclopropane complex from oxidative addition of an alkene to Al^I. Remarkably this reaction is reversible and reductive elimination of the alkene occurs at higher temperature reforming Al^I. Furthermore, in selected cases the organoaluminium products are susceptible toward β‐fluoride elimination to yield a double C?F activation pathway.     

浅说复杂环境下的化学结构和反应

<正>取3个玻璃杯,倒上水。分别加入1小勺花生油、蔗糖、食盐后摇晃几下,第一个杯子的水表面出现一个个小油珠,而第二、三杯子里的蔗糖和食盐则慢慢被溶解,见图1。常识告诉我们,由于水油不混溶,所以油在水中尽量保持自己原来的形态。蔗糖呢?晶体结构被水拆散,但单个的蔗糖分子结构依然不变。最可怜的是食盐,晶体结构被肢解后变成了在水中游荡的氯离子和钠离子。就是说,作为溶剂,水可能对溶质分子的结构产生巨大     

二硫代乙酰丙酮和某些金属离子络合反应的研究

报导CH₃COCH₂COCH₃/H-2S/C₂H₅OH-HCl体系和十六种金属离子以及Fe(CO)₅的反应,用X射线衍射法测定了九种反应产物的分子和晶体结构.本文结果总结出了该反应的规律性.研究表明,在该反应条件下,钼是唯一能够形成原子簇化合物的元素.