Theoretical Study on the New Ringed Molecules Containing Noble Gas, Polymeric Xe-Containing Molecules,and Polyacrylonitrile Thermo-Chemical Reactions

• Main Authors: FU,JUN-YI, 傅均溢
• Other Authors: Hu,Wei-ping
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/49518102112832106369

碩士 === 國立中正大學 === 化學暨生物化學研究所 === 104 === This thesis consists of four chapters. In the first chapter, we tried to find new stable ringed molecules containing noble gas atoms . In previous studies, we had shown that general formula OnXeO2CR1R2 (n = 2, 3; R1,R2 = H, CH3, F, Cl) four-member ringed molecules were not stable because of the ring strain. In the current study, we replaced the O atoms with N atoms, and extended the study to six-member rings. The general formula of these neutral molecules and anions was NgO2N2B2OR2、NgON3B2OR2 ( Ng = Xe、Kr )、( R=H、F ). We used MP2、CCSD(T) and B3LYP theory to predict the structures of these molecules. The results suggested that XeO2N2B2OF2、XeO2N2B2OH2、XeON3B2OF2、XeON3B2OH2all have large ST gaps. Our calculation also showed that the dissociation barriers are high. Our results thus suggested that these molecules could exist at the low temperature. In the second chapter, we studied the stabilities of molecules containing more than one noble gas atom. We used the MP2 and B3LYP theory to predict the structures of R(XeOBeO)nXeR (R = H or F；n = 1, 2) and their stabilities .The calculated results showed that for n = 1, the molecules HXeOBeOXeH、FXeOBeOXeH and FXeOBeOXeF are stable. The noble-gas bond energies of these molecules were 61.2、84.4 and 99.0 kcal/mol, respectively. The dissociation barriers were estimated to be higher than 35 kcal/mol at the CCSD(T)/aug-cc-pVTZ level.However, for n > 1, our calculation indicated that these molecules do not have enough stability even at low temperature. In the third chapter, we studied the mechanisms of the cyclization and dehydrogenation reactions of polyacrylonitrile (PAN). Our results showed that the barrier of cyclization reaction via self-generated CN free radical was about 18 kcal/mol, and the reaction is highly exothermic. Our calculation also showed that the direct dehydrogenation of 4AN needs to overcome barriers over 100 kcal/mol, and the overall reaction was highlyendothermic. We also calculated alternative dehydrogenation pathways at the presence of free radicals. The reactions only required barriers about -1.2 ~ 11 kcal/mol. We conclude that the free radical reactions are much more likely to occur in the dehydrogenation processes. In the fourth chapter, we studied the stabilities of two new type polymers containing more than one noble gas atom. The general formula are (FNgCC-Gly)n and (FNg CH2CCH3)n ( Ng = Kr、Xe ; n=1 ~ 4) The calculated results showed that FNgCC-Gly for Ng = Kr、Xe, the noble-gas bond energies were 28.7、57.2 kcal/mol.With the expansion of the molecular systems (n = 2、3、4) , the noble-gas bond energies were still more than 15、35 kcal/mol, respectively. For (FNg CH2CCH3)n with n > 2, the decomposition reaction would accompanies a radical shift, such that stability substantial declines.