| Autor: |
Djebra-Belmessaoud, Nadia, Kheffache, Djaffar |
| Předmět: |
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| Zdroj: |
Structural Chemistry; Oct2023, Vol. 34 Issue 5, p1657-1666, 10p |
| Abstrakt: |
The purpose of this article is to present insights on the mechanisms of formation of methanimine (CH2 = NH) a simplest five-atom molecule from the hydrogenation reaction of HCN in cold interstellar clouds. Using density functional theory (DFT) and the coupled cluster approach (CC), we investigated the two chemical pathways associated to methanimine production processes in detail. As the surface of interstellar grains presents very low temperatures, we were interested in the effect that low temperatures might have on the reaction enthalpy and activation barriers by lowering the temperature from 300 to 5 K. We have also studied the effect of bulk ice water on the enthalpy and the free enthalpy of the reaction. To model the effect of the bulk ice environment, two strategies were used: the implicit approach and the explicit approach. The implicit approach describes the bulky effects of ice water using the polarizable continuum model (PCM); the dielectric constant of ice is taken equal to 600. The second approach is to explicitly consider one to four water molecules surrounding the reactants and products of each reaction. Our results show that the formation of methanimine by the hydrogenation reaction of HCN is possible at very low temperatures both in the gas phase and in the ice-water environment. The reaction rate constants were calculated in the temperature range from 300 to 50 K using the transition state theory (TST). [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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