A theoretical investigation of the reaction between the amidogen, NH, and the ethyl, C₂H₅, radicals: a possible gas-phase formation route of interstellar and planetary ethanimine

Nadia Balucani (1) , Dimitrios Skouteris , Cecilia Ceccarelli (1) , Claudio Codella , Stefano Falcinelli , Marzio Rosi

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

The reaction between the amidogen, NH, radical and the ethyl, C₂H₅, radical has been investigated by performing electronic structure calculations of the underlying doublet potential energy surface. Rate coefficients and product branching ratios have also been estimated by combining capture and RRKM calculations. According to our results, the reaction is very fast, close to the gas-kinetics limit. However, the main product channel, with a yield of ca. 86-88% in the range of temperatures investigated, is the one leading to methanimine and the methyl radical. The channels leading to the two E-, Z- stereoisomers of ethanimine account only for ca. 5-7% each. The resulting ratio [E-CH₃CHNH]/[Z-CH₃CHNH] is ca. 1.2, that is a value rather lower than that determined in the Green Bank Telescope PRIMOS radio astronomy survey spectra of Sagittarius B2 North (ca. 3). Considering that ice chemistry would produce essentially only the most stable isomer, a possible conclusion is that the observed [E-CH₃CHNH]/[Z-CH₃CHNH] ratio is compatible with a combination of gas-phase and grain chemistry. More observational and laboratory data are needed to definitely address this issue.

Mots clés: Astrophysics - Earth and Planetary Astrophysics; Physics - Chemical Physics

Domaines: Planète et Univers [physics]

Nadia Balucani, Dimitrios Skouteris, Cecilia Ceccarelli, Claudio Codella, Stefano Falcinelli, et al.. A theoretical investigation of the reaction between the amidogen, NH, and the ethyl, C₂H₅, radicals: a possible gas-phase formation route of interstellar and planetary ethanimine. Molecular Astrophysics, 2018, 13, pp.30-37. ⟨10.1016/j.molap.2018.10.001⟩. ⟨insu-03693523⟩