导　　师： 李平

学科专业： 070304

授予学位： 硕士

作　　者： ;

机构地区： 曲阜师范大学

摘　　要： 在持久性有机污染物/(Persistent Organic Pollutants, POPs/)中，二噁英类化合物（PCDD//Fs）由于其高毒性、巨大的危害性而成为最受社会和科学界关注的污染物之一。近年来，PCDD//Fs的热力学性质参数、电子亲和势和降解机制成为人们普遍关注的研究热点。 本文主要运用密度泛函理论，并结合等键反应方法、自洽反应场中的可极化连续介质模型（PCM）以及自然键轨道理论（NBO）等方法，系统探讨了PCDD//Fs的热力学性质参数和电子亲和势的相关性质，阐明了1,3,6,8-TCDD与H自由基之间的反应机制。 本文主要分三个部分进行讨论研究： 首先，系统探讨了PCDD//Fs及其同系物的标准摩尔生成焓和标准摩尔吉布斯自由能等热力学参数及其相对稳定性，丰富了其相关的热力学参数。此外，根据相关的参数得到了各氯取代异构体的最稳定构型，为后续研究各氯取代异构体中最稳定化合物的电子亲和势及其与H自由基的反应机制奠定了基础。 其次，基于PCDD//Fs中各氯取代异构体的最稳定构型，系统探讨了其电子亲和势的相关性质。分析了单电子的引入对分子构型、振动频率和红外光谱产生的显著影响，阐明了电子亲和势的大小变化规律及影响因素；系统探讨了引入单电子的电荷分布及自旋密度分布。 最后，在上述研究的基础上，选取最稳定的1,3,6,8-TCDD为研究模型，系统考察了在H自由基的作用下，以它为起点的连续脱氯、开环降解的四种反应路径，通过分析反应过程中的能垒及反应热，阐明了四种路径的反应机制，给出了最佳的反应路径，这为实验上研究PCDDs的降解路径提供重要的科学依据和理论指导。 The polychlorinated dibenzo-p-dioxins /(PCDDs/) and dibenzofurans /(PCDFs/), among thePersistent Organic Pollutants /(POPs/) have posed a serious concern as a ubiquitous and extremelyhazardous class of organic pollutants. In recent years, the thermodynamic properties parameters,electron affinities, and degradation mechanisms of PCDD//Fs have become a hot topic. In this study, the thermodynamic properties parameters, electron affinities of PCDD//Fs, andthe successive reaction pathways of1,3,6,8-TCDD initiated by H radical have beensystematically investigated using density functional theory /(DFT/) in combination with theisodesmic reaction method, polarized continuum model /(PCM/), and natural bond orbital /(NBO/)methods. Three parts have been mainly discussed in this study as follows: First of all, the thermodynamic properties parameters, such as the standard molar enthalpy offormation and the standard molar Gibbs free energy, and stability of PCDD//Fs and its analogueshave been investigated systematically. The most stable isomers of PCDD//Fs substituted bydifferent chlorine atoms have been obtained on the basis of the related thermodynamic propertiesparameters, paving the way for the following studies on electron affinities of PCDD//Fs and thereaction between1,3,6,8-TCDD and H radical. Secondly, the electron affinities of the most stable isomer of PCDD//Fs substituted by differentchlorine atoms have been investigated systematically. The significant influences upon adding asingle electron on molecular structure, vibrational frequency, and infrared spectra have beenanalyzed. The relevant changes of electron affinities among PCDD//Fs have been clarified as wellas the solvent effects. Moreover, the population analyses and the spin density distributions havebeen discussed detailedly upon adding a single electron. Finally, the reaction mechanisms of1,3,6,8-TCDD initiated by H radical have beeninvestigated systematically. Four reaction pathways including the dechlorination reactions andring-open

关 键 词： 多氯二苯并 对 二噁英和多氯二苯并呋喃 热力学性质参数 电子亲和势 反应路径 密度泛函理论

领　　域： [理学] [理学]