2022A&A...663L...5C

We report the discovery of five cyano derivatives of propene towards TMC-1 with the QUIJOTE line survey: trans and cis-crotononitrile (t-CH₃CHCHCN, c-CH₃CHCHCN), methacrylonitrile (CH₂C(CH₃)CN), and gauche and cis-allyl cyanide (g-CH₂CHCH₂CN and c-CH₂CHCH₂CN). The observed transitions allowed us to derive a common rotational temperature of 7 ± 1 K for all them. The derived column densities are N(t-CH₃CHCHCN) = (5 ± 0.5) x 10¹⁰ cm^–2, N(c-CH₃CHCHCN) = (1.3 ± 0.2) x 10¹¹ cm^–2, N(CH₂C(CH₃)CN) = (1.0±0.1) x 10¹¹ cm^–2, N(g-CH₂CHCH₂CN) = (8.0 ± 0.8) x 10¹⁰ cm^–2, and N(c-CH₂CHCH₂CN) = (7.0 ± 0.7) x 10¹⁰ cm^–2, respectively. The abundance of cyano-propene relative to that of propene is thus ∼10^–2, which is considerably lower than those of other cyano derivatives of abundant hydrocarbons. Upper limits are obtained for two ethynyl derivatives of propene (E and Z-CH₃CHCHCCH).