Monocyanopolyynes are formed by arcing graphite electrodes in ammonia. This work completes the parallelism existing between the polyynes formed by laser ablation experiments of graphite targets and those produced from the submerged electric arc. In both cases the same products are obtained. The products consist of hydrogen-terminated polyynes if water is present, monocyanopolyynes (mixed with hydrogen-terminated polyynes) if the carbon arc is sparked in acetonitrile or ammonia and dicyanopolyynes if the arc is struck in liquid nitrogen. The mechanism of formation of polyynes in the submerged carbon arc involves essentially neutral species; similar species and pathways may also occur in the circumstellar environment where polyynes have been detected by radioastronomy. It is shown that the relative abundances of the polyynes formed in the submerged carbon arc or in a carbon arc in vacuum decrease by a factor between three and five as the chain length increases by a C2 unit. Exactly the same trend has been observed by radioastronomy both for polyynes and cyanopolyynes in the circumstellar environment around red giants and asymptotic giant branch (AGB) stars. This fact may be a simple coincidence or may suggest that the mechanism of formation of the polyynes in the carbon arc is the same as that occurring in the surroundings of carbon-rich stars.

Monocyanopolyynes and dicyanopolyynes can be synthesized quite easily by the submerged electric arc. Monocyanopolyynes having the general formula H[bond](C[triple bond]C)n[bond]C[triple bond]N can be synthesized together with ordinary polyynes series H[bond](C[triple bond]C)n[bond]H by arcing graphite electrodes in acetonitrile. Dicyanopolyynes N[triple bond]C[bond](C[triple bond]C)n[bond]C[triple bond]N are produced almost pure by arcing graphite electrodes directly into liquid nitrogen. These molecules are present in the envelope of post-AGB (asymptotic giant branch), carbon-rich giant stars and also in dark molecular clouds. They are incorporated into comets and also into other primitive materials and may play a role in the prebiotic synthesis of more complex organic molecules having a biological significance. Furthermore, the cyanopolyynes are involved in the atmospheric chemistry of some bodies of the solar system. The discovery of the easy formation of these molecules under laboratory conditions may explain why these molecules are so ubiquitous in space and may also stimulate new ideas about the mechanism of their formation.