【作者】 孔京；

【导师】 张香文；

【作者基本信息】 天津大学 ， 化学工艺， 2011， 博士

【摘要】 高能量密度燃料具有非常广泛的用途,研究此类燃料不但具有重要学术理论意义,而且有深远的应用价值。但当前绝大多数研究仅局限于实验合成,燃料化学理论研究非常少。本文对高密度燃料设计与合成的基础理论进行了系统研究,包括燃料的分子设计及性能评估、燃料分子定向合成的反应历程模拟,为高密度燃料的合成提供理论指导和技术支持。选取高密度燃料的探针体系主要包括三类:多环烃类、金刚烷类和芳香烃类。研究内容提纲如下:为寻求新的潜在高能量密度燃料,理论设计出三类52种多环烃类:环丙烷化和甲基取代的多环烃、[n]棱烷和立方烷类衍生物。运用基团贡献法和量子化学方法,估算其物化性质和能量特性。通过分子设计及物性评估,建立多环烃类燃料的热力学物性基础理论,为燃料的合成历程设计和异构重排模拟提供依据。计算模拟以双环戊二烯(DCPD)为原料定向合成多环烃类燃料的微观反应机理:Diels-Alder?加氢和环丙烷化过程,并获悉模拟体系的构型筛选、电子结构、热力学性质、动力学性质、桥式规则、协同反应机理等多环烃类燃料反应合成的基础理论成果,为燃料异构重排研究奠定基础。以多环烃类为探针分子,研究多环烃类燃料的卤代异构Wagner-Meerwein重排反应理论,包括camphenyl、norbornyl和pinayl三类高密度燃料重排体系。用新型的非经典离子对理论,系统阐述崁烷离子对模型的构建、降冰片基离子对“leakage”路径、多通道蒎烷离子对重排过程、离子对效应、溶剂化效应以及整个体系反应势能面的特征化等多环烃类燃料异构的基础理论。以金刚烷烯为探针分子,研究金刚烷类燃料的卤代反应理论。提出金刚烷烯卤代反应的三种可能机理:自由基、离子对和自由基正离子。区别于经典的碳正离子假设,离子对机理合理阐述该特征反应的区域选择性和立体专一性的根源。以苯、萘、蒽和菲为探针分子,研究芳香烃类高密度燃料的卤代反应理论。探索苯及苯系芳烃与卤素的加成反应与取代反应的固有竞争性。采用离子对模型,给出了较经典Wheland正离子更完整的苯-溴分子反应势能面,提出苯的直接亲电取代的协同机理,发现芳烃加成反应比取代更具固有优势,获得取代产物的加成-消去路径、不包含任何Wheland中间体等重要计算发现,完善并丰富了芳烃卤代反应的经典理论。更多还原

【Abstract】 High energy density fuel has a large variety of uses. The investigation of such fuel not only adds to the significant scientific treasure, but also possesses long-standing practical application prospect. However, the majority of the current studies merely focus on the experimental synthetic aspect. The theoretical field of fuel chemistry is very rare.In this paper, the systematical exploration is mainly carried on the high density fuel chemistry theory, including the molecular design of goal fuel, physicochemical properties and propulsion performances evaluation of polycyclic hydrocarbon, profound revelation of microscopic mechanistic course for oriented synthesis of high enrgy density fuel. Such key theoretical findings provide prominent technical support for the practical operation of synthesizing high energy density fuel. Three targeted high-density fuel systems are included: polycyclic hydrocarbons, adamantane-fused and arene-fused hydrocarbon. The outline of the whole paper is listed as follows:In pursuit of novel, potential high energy density fuel, fifty-two polycyclic hydrocarbons are theoretically designed, including: cyclopropane and methyl derivative polyclic alkenes, [n] prismane and cubane derivatives. Their physico-chemical properties and propulsion performances are evaluated, employing with group contribution method and quantum chemistry method. In view of molecular design and property estimation rational, the fundamental theory of thermodynamical properties for polycyclic hydrocarbon fuels provides a powerful guide for synthetic mechanism and isomerization simulation.The intrinsic reaction mechanisms of dicylopentadiene-based synthesis of polycyclic hydrocarbon fuels are computationally simulated, including two vital probe routes: Diels-Alder-hydrogenation and cyclopropanation. These configurations screening, electronic structures, thermodynamical properties, kinetic properties, high endo/exo selectivity and concerted mechanism are proposed. These fruitful outcomes of targeted system lay a theoretical foundation for subsequent isomerization and optimality of high-performance energy density fuel.The Wagner-Meerwein arrangement theory for isomerization and optimality of high density fuels are systematically elucidated with polycyclic hydrocarbons as the probe molecules. Three rearranged reaction systems of high density fuels are computationally explored: camphenyl, norbornyl and pinayl category. Introducing“nonclassical”ion pair concept in the isomerization process, the camphenyl ion-pair model construction, norbornyl ion-pair“leakage”pathways, multi-channel pinayl ion-pair rearranged process, ion-pairing effect, solvation effect and potential energy surface characterization of whole vital systems are emphatically elucidated in the range of essential isomerization theory of polycyclic hydrocarbon fuels.The adamantane-fused fuel chemistry theory is consecutively expanded with the adamantylideneadamantane as the probe molecule. Three probable mechanistic proposals for the halogenation of adamantylideneadamantane are computationally posed: free radical, ion pair and radical cation. The instinctive origin for its remarkable region-selectivity and stereospecificity is stressed in view of prevalence of ion pair mechanism, instead of“classical”carbocation mechansim.The arene-fused fuel further enriches fundamental halogenation theory of high density fuel. Four popular arenes are specifically probed in detail here, including benzene, naphthalene, anthracene and phenanthrene. The inherent competition between electrophilic substitution and addition for the reaction of arene-Br2 is systematically exploited. In contrast to the“classical”Wheland ion postulate, the potential energy surface of benzene-Br2 reaction is wholly enriched by incorporating the vital role of the counter-ion in the mechanistic course (i.e. ion-pairing effect). Several significant computational findings are greatly challenging with classical theory widely existed in textbook, including direct and concerted mechanism of electrophilic substitution, inherent preference of addition pathway over substitution pathways, involving no Wheland intermediate, acquired substituted products via the alternative stepwise addition-elimination route.更多还原