Molecular Design And Mechanistic Simulation On Orientated Synthesis Of High Energy Density Fuel

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.