THE DETECTION OF INTERSTELLAR ETHANIMINE (CH ₃ CHNH) FROM OBSERVATIONS TAKEN DURING THE GBT PRIMOS SURVEY

Abstract

We have performed reaction product screening measurements using broadband rotational spectroscopy to identify rotational transition matches between laboratory spectra and the Green Bank Telescope PRIMOS radio astronomy survey spectra in Sagittarius B2 North (Sgr B2(N)).The broadband rotational spectrum of molecules created in an electrical discharge of CH 3 CN and H 2 S contained several frequency matches to unidentified features in the PRIMOS survey that did not have molecular assignments based on standard radio astronomy spectral catalogs. Several of these transitions are assigned to the E-and Z-isomers of ethanimine. Global fits of the rotational spectra of these isomers in the range of 8 to 130 GHz have been performed for both isomers using previously published mm-wave spectroscopy measurements and the microwave measurements of the current study. Possible interstellar chemistry formation routes for E-ethanimine and Z-ethanimine are discussed. The detection of ethanimine is significant because of its possible role in the formation of alanineone of the twenty amino acids in the genetic code.

Discovery of the interstellar chiral molecule propylene oxide (CH 3 CHCH 2 O)

“…In these regions, molecules are often liberated into the gas phase via nonthermal, shock-driven desorption, resulting in colder, spatially extended gas-phase populations that are often more abundant than predicted by standard warm-up models (14). This is consistent with the observation that the structurally similar ethylene oxide is consistently found to have low excitation temperatures (11 to 35 K), well below the temperature of the surrounding grains (15), with the detections of glycolaldehyde (11), ethanimine (16), and propylene oxide's structural isomers propanal (13) and acetone (8), in this region, and with the general pattern of shock-driven liberation of complex molecules in the so-called central molecular zone (14).…”

Chemical Modeling for Predicting the Abundances of Certain Aldimines and Amines in Hot Cores

“…They recommended that ethanimine from the C 2 H 5 N isomeric group should be a possible interstellar molecule which can be seen in space. Finally, ethanimine has been detected with both the forms in the same sources where methanimine has already been observed (Loomis et al 2013). …”

“…From our quantum chemical calculation, we found that E-ethanimine is energetically more stable (4.35 KJ/mol by using MP2/6-311G++(d,p) and 1.2 KJ/mol by using G4 composite method) than Z-ethanimine. Quan et al (2016) and Loomis et al (2013) obtained an energy difference of 4.60 KJ/mol and 4.24 KJ/mol respectively between these two conformers. We have shown the enthalpy of formation values for all the species in Table 2 along with the experimentally obtained values, where available.…”

Submillimeter spectra of 2-hydroxyacetonitrile (glycolonitrile; HOCH2CN) and its searches in GBT PRIMOS observations of Sgr B2(N)

“…We do not, however, make the assumption that this temperature is described by local thermodynamic equilibrium (LTE), meaning that the excitation temperature is not thermalized to the kinetic temperature of the gas. This approach has previously proven to be successful in modeling both the emission and absorption of molecules in PRIMOS observations (Hollis et al 2004;Loomis et al 2013;McGuire et al 2016). We note, however, that several other molecules exhibit populations which cannot be described by a single excitation temperature (McGuire et al 2012;Faure et al 2014), and thus care should be taken to examine any single-excitation temperature results on a case-by-case basis.…”