|
Description
We consider six isomeric groups (CH_3_N, CH_5_N, C_2_H_5_N, C_2_H_7_N, C_3_H_7_N, and C_3_H_9_N) to review the presence of amines and aldimines within the interstellar medium (ISM). Each of these groups contains at least one aldimine or amine. Methanimine (CH_2_NH) from CH_3_N and methylamine (CH_3_NH_2_) from CH_5_N isomeric group were detected a few decades ago. Recently, the presence of ethanimine (CH_3_CHNH) from C_2_H_5_N isomeric group has been discovered in the ISM. This prompted us to investigate the possibility of detecting any aldimine or amine from the very next three isomeric groups in this sequence: C_2_H_7_N, C_3_H_7_N, and C_3_H_9_N. We employ high-level quantum chemical calculations to estimate accurate energies of all the species. According to enthalpies of formation, optimized energies, and expected intensity ratio, we found that ethylamine (precursor of glycine) from C_2_H_7_N isomeric group, (1Z)-1-propanimine from C_3_H_7_N isomeric group, and trimethylamine from C_3_H_9_N isomeric group are the most viable candidates for the future astronomical detection. Based on our quantum chemical calculations and from other approximations (from prevailing similar types of reactions), a complete set of reaction pathways to the synthesis of ethylamine and (1Z)-1-propanimine is prepared. Moreover, a large gas-grain chemical model is employed to study the presence of these species in the ISM. Our modeling results suggest that ethylamine and (1Z)-1-propanimine could efficiently be formed in hot-core regions and could be observed with present astronomical facilities. Radiative transfer modeling is also implemented to additionally aid their discovery in interstellar space.
|
