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

Abstract

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.

References in corpus (11)

• Towards standard methods for benchmark quality ab initio thermochemistry --- W1 and W2 theory
• Our astrochemical heritage
• Assessment of W1 and W2 theories for the computation of electron affinities, ionization potentials, heats of formation, and proton affinities
• The genealogical tree of ethanol: gas-phase formation of glycolaldehyde, acetic acid and formic acid
• Can Formamide Be Formed on Interstellar Ice? An Atomistic Perspective
• Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey
• The Detection of Interstellar Ethanimine (CH3CHNH) from Observations taken during the GBT PRIMOS Survey
• The (impossible?) formation of acetaldehyde on the grain surfaces: insights from quantum chemical calculations
• Survey Observations of a Possible Glycine Precursor, Methanimine (CH${}_2$NH)
• Methanol formation via oxygen insertion chemistry in ice
• Laboratory measurements and astronomical search for cyanomethanimine

Cited by in corpus (12)

• Interstellar dimethyl ether gas-phase formation: a quantum chemistry and kinetics study
• A twist on the reaction of the CN radical with methylamine in the interstellar medium: new hints from a state-of-the-art quantum-chemical study
• The trans/cis ratio of formic, HCOOH, and thioformic, HC(O)SH, acids in the Interstellar Medium
• The origin of the E/Z isomer ratio of imines in the interstellar medium
• The Role of State-of-the-Art Quantum-Chemical Calculations in Astrochemistry: Formation Route and Spectroscopy of Ethanimine as a Paradigmatic Case
• The GRETOBAPE gas-phase reaction network: the importance of being exothermic
• ALMA-IMF XI: The sample of hot core candidates A rich population of young high-mass proto-stars unveiled by the emission of methyl formate
• A sequential acid-base (SAB) mechanism in the interstellar medium: The emergence of cis formic acid in dark molecular clouds
• Ion-molecule routes towards cycles in TMC-1. An automated study of the C2H4 + CH2CCH+ reaction
• Collisional excitation and non-LTE modelling of interstellar chiral propylene oxide
• A Computational Study of the Reaction Cyanoacetylene and Cyano Radical leading to 2-Butynedinitrile and Hydrogen Radical
• The S${}^{+}$(${}^4$S) + SiH${}_2$(${}^1$A${}_1$) Reaction: Toward the Synthesis of Interstellar SiS