Cyanopropyne, CH₃C₃N, also known as methylcyanoacetylene or methylpropionitrile, has been detected with the 45 m NRAO telescope in the J = 6 – 5 to 8 – 7 transitions with K = 0 and 1 between 27.7 and 33.1 GHz in emission toward TMC-1, by
N. W. Broten, J. M. MacLeod, L. W. Avery, W. M. Irvine, B. Höglund, P. Friberg, and Å. Hjalmarson,
Detection of Interstellar Methylcyanoacetylene
Astrophys. J. 276, L25–L29 (1984).
In addition, the J = 5 – 4, K = 0 transition was barely detected.

C. Cabezas, E. Roueff, B. Tercero, M. Agúndez, N. Marcelino, P. de Vicente, and J. Cernicharo
reported on the
Detection of deuterated methylcyanoacetylene, CH₂DC₃N, in TMC-1
Astron. Astrophys. 650, Art. No. L15 (2021).
The molecule was identified through 15 a-type transitions with 7 ≤ J ≤ 12 and K_a = 0 and 1 in the course of a molecular line survey of the prototypical cold dark molecular cloud TMC-1 carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. A value of T_rot = 8.0 ± 0.5 K was derived. The column density of monodeuterated methylcyanoacetylene is about a factor of 22 lower than that of the fully hydrogenated isotopolog; thus the H/D ratio per H atom is about 66.

Contributor(s): H. S. P. Müller; 08, 2012; 06, 2021