2021ApJ...920L..27Z

Amines, particularly primary amines (R-NH₂), are closely related to the primordial synthesis of amino acids since they share the same structural backbone. However, only a limited number of amines has been identified in the interstellar medium, which prevents us from studying their chemistry as well as their relation to prebiotic species that could lead to the emergence of life. In this Letter, we report the first interstellar detection of vinylamine (C₂H₃NH₂) and tentative detection of ethylamine (C₂H₅NH₂) toward the Galactic center cloud G+0.693-0.027. The derived abundance with respect to H₂ is (3.3 ± 0.4) x 10^–10 and (1.9 ± 0.5) x 10^–10, respectively. The inferred abundance ratios of C₂H₃NH₂ and C₂H₅NH₂ with respect to methylamine (CH₃NH₂) are ∼0.02 and ∼0.008, respectively. The derived abundance of C₂H₃NH₂, C₂H₅NH₂, and several other NH₂-bearing species are compared to those obtained toward high-mass and low-mass star-forming regions. Based on recent chemical and laboratory studies, possible chemical routes for the interstellar synthesis of C₂H₃NH₂ and C₂H₅NH₂ are discussed.