The catalytic effects of various third molecules on reaction channels of weakly bound complex CO2 HF systems in the vapor phase |
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Authors: | Shyh-Jong Chen Cheng Chen Yaw-Shun Hong |
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Institution: | aDepartment of Applied Chemistry, Chung-Cheng Institute of Technology, National Defense University, Ta-His, Taoyuan 33509, Taiwan, ROC |
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Abstract: | In this investigation, reaction channels of weakly bound complexes CO2 HF, CO2 HF H2O, CO2 HF NH3, CO2 HF CH3OH, CO2 HF NH2CH3, CO2 HF NH(CH3)2 and CO2 HF N(CH3)3 systems were studied at the B3LYP/6-311++G(3df,2pd) level. The conformers of syn-fluoroformic acid or syn-fluoroformic acid plus a third molecule (H2O, NH3, CH3OH, NH2CH3, NH(CH3)2 or N(CH3)3) were found to be more stable than the conformers of the related anti-fluoroformic acid or anti-fluoroformic acid plus a third molecule (H2O, NH3, CH3OH, NH2CH3, NH(CH3)2 or N(CH3)3). However, the weakly bound complexes were found to be more stable than either the related syn- and anti- type fluoroformic acid or the acid plus third molecule (H2O, NH3, CH3OH, NH2CH3, NH(CH3)2 or N(CH3)3) conformers. They decomposed into CO2+HF, CO2+H3OF, CO2+NH4F, CO2+(CH3)OH2F, CO2+NH3(CH3)F, CO2+NH2(CH3)2F, or CO2+NH(CH3)3F combined molecular systems. The weakly bound complexes have seven reaction channels, each of which includes weakly bound complexes and their related systems. Moreover, each reaction channel includes two transition state structures. The transition state between the weakly bound complex and anti-fluoroformic acid type structure (T13) is significantly higher than that of internal rotation (T23) between the syn- and anti-FCO2H (or FCO2H H2O, FCO2H NH3, FCO2H CH3OH, FCO2H NH2CH3, FCO2H NH(CH3)2, or FCO2H N(CH3)3) structures. However, adding the third molecule H2O, NH3, CH3OH, NH2CH3, NH(CH3)2 or N(CH3)3 can significantly reduce the activation energy of T13. The catalytic strengths of the third molecules are predicted to follow the order H2O<NH3<CH3OH<.NH2CH3<NH(CH3)2<N(CH3)3. |
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Keywords: | Syn-fluoroformic acid or syn-fluoroformic acid plus a third molecule Anti-fluoroformic acid or anti-fluoroformic acid plus a third molecule Weakly bound complex The activation energy |
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