Mechanism Study On Synthesis Reaction Of Novel High Energy Density Fuels

The high energy density fuels（HEDF） is essential to improving the performance of volume-limited aircrafts such as missiles and rockets. The investigation of such fuels are beneficial not only to the extension of their scientific knowledge, but also to their further industrial applications. In this dissertation, the novel computational method is employed to explore mechanism for synthesis reaction of novel fuels, rendering theoretical support for experimental preparation of such fuels.The cyclopropanation of endo-dicyclopentadiene（endo-DCPD） with Simmons-Smith zinc carbenoids has been investigated. It proceeds via methylene-transfer pathway. In gas phase, the channels with monomeric IZnCH₂ I attacking the double bond from the exo-face have much lower barrier(about 16.17^-18.43 kcal mol^-1), thus, the primary cyclopropanated compounds are exoproducts P1 and P3, and the sole final product is P5, representing remarkable stereospecificity. When considering bulk solvent effect of the diethyl ether solvent, the barriers are decreased by 0.50-7.77 kcal mol^-1. The solvated（ICH₂）2Zn can lead to a further tiny reduction(about 0.18-2.30 kcal mol^-1) of the barriers. In addition, the solvated IZnCH₂ I and（ICH₂）2Zn do not change the reaction pathways and retain the stereospecificity. Our computational results agree with the experimental observations quite well, and suggest that both IZnCH₂ I and（ICH₂）2Zn might be the active species in current reaction system.The mechanism for hydroamination of acetylene with ammonia catalyzed by AlCl₃, ZnCl₂, CuCl₂ is proposed. The whole catalytic cycle proceeds via the ammonia nucleophilic addition, the first proton transfer, the particular metal chloride migration and the subsequent second proton transfer step. During the reaction, the excessive ammonia molecule not only acts as the nucleophile, but also an efficient proton transfer agent, drastically promoting two proton transfer step. In gas phase, the final product is imine for hyroamination catalyzed by both ZnCl₂ and AlCl₃, whereas the final product is enamine for that catalyzed by CuCl₂. In acetone and toluene solvents, only the second proton transfer is drasitically enhanced and thus the final product turns to imine product for all AlCl₃, ZnCl₂, Cu Cl₂ catalysts. Thus, the metal chloride catalytic hydroamination of acetylene with ammonia is kinetically favorable in solvents.The hydrogenation reaction of acetylene on ⁵FeO、9Fe₂O₃ and ⁵Fe₃O₄ clusters（numbers are their spin multiplicity）, a model reaction of catalytic hydrogenation reaction on the FexOy cluster, are theoretically investigated. The catalytic hydrogenation reaction proceeds via four consecutive steps: the C2H₂ adsorption on Fe atom, the H₂ dissociation on Fe-O bond, the addition of dissociated H on acetylene and the final product desorption. On ⁵FeO cluster, the extremely higher barrier 60 kcal mol^-1 for addition of the H atom absorbed on O atom predicts the unfeasibility of acetylene hydrogenation on ⁵FeO cluster. On 9Fe₂O₃ and ⁵Fe₃O₄ clusters, H₂ tends to be dissociated on Fe-O bond where acetylene is adsorbed on its Fe atom. Then the two dissociated H atoms are added on C2H₂ triple bond to form C2H4 that can be further hydrogenated to C2H6. The H atom addition barriers for the favorable pathway on ⁵Fe₃O₄ cluster are 0 kcal mol^-1, 21.33 kcal mol^-1 for C2H₂ primary hydrogenation（C2H₂�'C2H4） and 0.3 kcal mol^-1, 24.89 kcal mol^-1 for its further hydrogenation（C2H4�'C2H6）, all much lower than that on 9Fe₂O₃ cluster. Therefore, among three FexOy clusters, ⁵Fe₃O₄ cluster is most favorable to catalyze the complete hydrogenation of acetylene to form ethane at relatively low temperature.