O-酰基-α-酮肟光分解机理的研究

本文用红外光谱法对O-酰基-α-酮肟R^2C(O)ON=C(R^1)C(O)R^1的光分解机理进行了研究, 并通过对反应物消失和分解产物生成的动力学方程的拟合, 求得了表观动力学速率常数。结果表明, N-O键断裂和Norrish反应在光分解反应中同时存在, 不同的R^1、R^2取代基影响这两种断裂方式的比例。     

3—芳酰基乙基斯德酮在浓盐酸中的分离反应

3－芳酰基乙基斯德酮与过量浓盐酸在乙酸酯中于室温下反应，生成3－芳酰基乙基斯德酮的盐酸盐，而将3－芳酰基乙基乙基斯德酮与不同量的盐酸在乙酸乙酯中回流，则得到1－芳酰基乙基－3－芳基吡唑啉，此外，33－芳酰基乙基－4－溴斯德酮在类似条件下分解得到的相应的1－氯甲酰吡唑啉。     

α-苯磺酰基环十二酮肟酯的合成及其除草活性

以环十二酮为原料, 经过α-取代反应生成中间体α-苯磺酰基环十二酮, 先与NH2OH作用成肟然后酯化反应合成了20个未见文献报道的α-苯磺酰基环十二酮肟酯衍生物(8), 其化学结构经1H NMR, IR和元素分析确证. 初步生物活性测定结果显示, 部分化合物具有一定的除草活性, 如α-苯磺酰基环十二酮肟-2,4-二氯苯氧乙酸酯(8p)在浓度为100和1 mg/L时对马唐(Digitaria sanguinalis)的抑制率分别为100%和80.07%; 对苘麻(Abutilon theophrasti)的抑制率分别为100%和88.70%. 毒力测定结果显示, OE16对马唐的IC50值和苘麻的IC50值分别为0.192和0.151 mg/L.     

甾体酮肟的贝克曼重排反应

扼要介绍了不对称酮肟立体异构体的贝克曼重排是具有立体有择性的反应。酮肟的顺反构型可确定转移到氮上的基团。肟重排的结果是羟基只能和它处于反位的基团调换位置（即反式位移）。α，β－不饱和酮肟有顺反两种异构体。α，β－不饱和甾体酮肟的贝克曼重排产物通常是从其顺式同分异构体生成，而其反式同分异构体不进行贝克曼重排。     

低价钛引起的芳酮肟的反应

在低价钛试剂 (TiCl4/Sm)作用下取代苯乙酮肟发生脱肟反应生成酮 ,而在同样条件下 ,二芳酮肟则生成二芳酮、胺或希夫碱     

微波辐射下干反应脱肟成酮的一种新方法

肟已被广泛用于羰基化合物的表征、纯化以及酰胺的合成[1 ] 。人们可以从羰基和非羰基化合物来制备肟 (Ｂａｒｔｏｎ反应[2 ,3] )。因此 ,肟的脱肟成酮也是合成羰基化合物的一种方法。近年来 ,文献中不断有各种脱肟试剂和催化剂 ,如 :三氧化铬 硅胶[4] 、镍 (Ⅱ )复合物[5] 等的研究报道。但这些方法都是在液相中进行的 ,通常需要计量或过量的有机试剂 ,而且反应时间长、产率低[6] 。为了寻找高效的脱肟方法 ,微波辐射下的干反应脱肟研究已愈来愈引起人们的兴趣[1 ,7] ,它具有反应速度快、副反应少、产率高等优点。前文[8] 我们报道了用甲酸…     

交联聚苯乙烯二醋酸碘苯的合成及其在酮肟氧化反应中的应用

合成了新型聚合物高碘试剂聚苯乙烯二醋酸碘苯,它可在中性条件下使酮肟氧化成酮。     

α‘—苯磺酰基—α,β—不饱和酮与环戊二烯的不对称催化Diels—Alder反应

在手性金属钛催化剂存在下，研究了α＇－苯磺酰基－α，β－不饱和酮与环戊二烯的不对称催化Ｄｉｅｌｓ－Ａｌｄｅｒ反应；讨论了亲双烯体上不同取代基对反应活性和环加成产光学纯度的影响；鉴定了环加成产物的构型，得到了高收率和高光学纯度的环加成产物。     

分形表面上CO氧化反应的蒙特卡罗模拟

众所周知,人们在理想完好的单晶表面上的动力学研究已取得了很大的成功[1],然而对许多实际催化剂来说,传统催化理论和实验之间不符的情况仍然俯拾皆是．现在人们对造成这种情况的原因已经有了更加深入的认识：大量的实验事实表明,在表面催化反应体系中,不但催化剂表面具有复杂的分形结构,而且催化剂表面上的活性中心分布也具有复杂的分形特性[2]．“分形”是指那些具有分数维数的几何对象．这些对象往往是不规则的,不能用通常的欧氏几何来描述[3]．将分形引入催化科学中最早的是Pfeifer和Avnir等[4]人,至今已有近二十年的历史,现…     

Monte Carlo Simulation of Polymer Reactions at Interfaces

Adhesion of immiscible polymers during two‐component injection moulding may be improved by transreactions of properly functionalised components. We performed MC simulations based on the three‐dimensional coarse‐grained bond fluctuation model (BFM) including a thermal interaction potential in with energy to characterise the behaviour of several selected types of chemical reactions, which are governed by activation energies of E_A = 0, 1, 3 and 5 k_BT. The consumption of reactive monomers for all the reactions in the time interval below the Rouse time τ_R exhibits a typical crossover from a kinetic‐controlled to a diffusion‐controlled behaviour and can be described by a bimolecular kinetic ansatz.

     

自由基聚合反应的Monte Carlo模拟方法

本文将化学反应动力学的MonteCarlo模拟方法运用到引发剂引发的自由基聚合反应的非稳态动力学,针对自由基聚合反应动力学数值模拟所特有的"无伸缩问题",采用"偏倚抽样法"解决了MonteCarlo模拟中的"无伸缩问题",模拟结果与非稳态动力学解的结果完全一致,此算法易推广到研究更复杂的自由基聚合反应体系。     

碘离子催化的H2O2-BAT反应的Monte Carlo模拟

催化动力学分析是痕量分析中检测下限低、选择性较好的一种方法,但目前分析工作者对所用的反应机理常不明瞭,仅能作为“黑箱”应用之。模拟技术可为探讨这类分析反应机理提供有用的信息。前文^[1]报道用溴胺T(BAT)离子电极、跟踪碘离子催化的BAT-H₂O₂反应测定痕量碘效果甚佳。     

Studies on the Adsorption of Asymmetrical Triblock Copolymers by Scheutjens-Fleer Theory and Monte Carlo Simulation

The adsorption of asymmetrical triblock copolymers from a non-selective solvent on solid surface has been studied by using Scheutjens-Fleer mean-field theory and Monte Carlo simulation method on lattice model. The main aim of this paper is to provide detailed computer simulation data, taking A8-kB20Ak as a key example, to study the influence of the structure of copolymer on adsorption behavior and make a comparison between MC and SF results. The simulated results show that the size distribution of various configurations and density-profile are dependent on molecular structure and adsorption energy. The molecular structure will lead to diversity of adsorption behavior. This discrepancy between different structures would be enlarged for the surface coverage and adsorption amount with increasing of the adsorption energy. The surface coverage and the adsorption amount as well as the bound fraction will become larger as symmetry of the molecular structure becomes gradually worse. The adsorption layer becomes thicker with increasing of symmetry of the molecule when adsorption energy is smaller but it becomes thinner when adsorption energy is higher. It is shown that SF theory can reproduce the adsorption behavior of asymmetrical triblock copolymers. However, systematic discrepancy between the theory and simulation still exists.The approximations inherited in the mean-filed theory such as random mixing and the allowance of direct back folding may be responsible for those deviations.     

表面活性剂与高分子链混合体系的模拟

计算机模拟了高分子链对表面活性剂胶束形成过程的影响，以及高分子链构象性质随胶束化过程的变化.结果表明,当高分子链与表面活性剂之间的相互作用强度超过临界值后，高分子链的存在有利于表面活性剂胶束的形成.临界聚集浓度（CAC）与临界胶束浓度（CMC）的比值CAC/CMC随高分子链长的增大和相互吸引作用的增强而减小.在CAC之前，高分子链与表面活性剂分子只有动态的聚集；但在CAC之后，表面活性剂胶束随表面活性剂浓度X的增加而增大，并静态地吸附在高分子链上，形成表面活性剂/高分子聚集体.随着表面活性剂分子的加入，高分子链的均方末端距和平均非球形因子先保持恒定；从X略小于CAC开始， 和快速减小，至极小值后又逐渐增大.模拟结果支持高分子链包裹在胶束表面的实验模型.     

蒙特卡罗法估算真实溶液的无限稀释活度系数

在无限稀释活度系数实验测定、模型预测等方面的研究工作不断深入的同时，基干系统的微观分子结构信息通过计算机分子模拟方法来求取无限稀释活度系数的研究也更多地开展起来［‘，’］．但是鉴于摘类热力学性质，如自由能、化学位等的特殊性，开展的模拟工作总的说来是初步的·许多方法复杂，实现的难度较大，而研究的系统技多地针对于模型流体混合物（modelfluidrn－ixtures）．本文是蒙特卡罗法估算真实溶液的无限稀释活度系数的一个尝试，研究对象选取298．15K温度条件下甲醇的水溶液·1原理对于一个NTV系综，化学位定义为可以将UN－…     

端点附壁的高分子链形状的Monte Carlo模拟

分别基于简立方格点和四面体格点模型对一端吸附在无限大平面的高分子链（平面接枝高分子链）的形状进行了Ｍｏｎｔｅ Ｃａｒｌｏ模拟,结果表明,接枝高分子链的形状更偏离球形,〈Ｌ＾２１〉：〈Ｌ＾２２〉：〈Ｌ＾２３〉的极限值约为１：２．７５：１２．５,其中〈Ｌ＾２１〉,〈Ｌ＾２２〉和〈Ｌ＾２３〉分别为回转半径张量的本征值Ｌ＾２１,Ｌ＾２２和Ｌ＾２３（Ｌ＾２１〈Ｌ＾２２〈Ｌ＾２３）的统计平均;链长相同时,接枝     

Monte Carlo Studies on the Deformation Behavior of Entangled Polymer Chains

In this work we present a continuous three‐dimensional bond‐fluctuation model (CBFM) in combination with the method of confined self‐avoiding walks (CSAW). This method enables us to analyse both the compression and the stretching regime of the deformation process of two entangled polymer chains. We studied the deformation behavior in respect to the number of entanglements, the distance of the end monomers on the confining surfaces and the orientation of the entanglements to the deformation axis. Our analysis of the behavior of the force and the structural properties of the systems during the deformation process leads us to the assumption that the entanglements act as one topological crosslink with variable strength.     

Monte Carlo Simulation in Electron Probe Microanalysis. Comparison of Different Simulation Algorithms

Practical aspects of Monte Carlo simulation of EPMA experiments are considered. Simulations are performed using the general-purpose Monte Carlo code system Penelope, which is briefly described. This code includes geometry tools and variance reduction methods that allow the practical simulation of x-ray spectra from samples with complex geometries in moderate computing times. The reliability of simple interaction models and approximations, which have been frequently used in EPMA studies, is analyzed by studying their effects on the simulated x-ray spectra.