For a wide-ranging and authoritative review of prebiotic astrochemistry and the formation of molecules of astrobiological interest in interstellar clouds and protostellar disks see Sandford et al. A comprehensive study of peptide-like bond molecules, the GUAPOS project, cluding that the first five of these species which were detected are formed on grain surfaces and later released to the gas-phase by either thermal or shock-triggered desorption. Frigge et al. have calculated adiabatic ionisation energies of a number of C 2 H 5 NO isomers in a vacuum ultraviolet photoionisation study of the formation of N-methyl formamide in deep space. But there has not been a comparable study to that of Gronowski et al. on the structure and spectroscopy of C 2 HNO isomers for the C 2 H 5 NO isomers. However a case study investigation of the possible routes to the formation of acetamide in the interstellar medium (ISM) effectively studied its constitutional isomers, creating 198 structures of which 91 were unique. Further refinement led to 53 unimolecular species § at the G3MP2B3 level of theory from which the authors deduced that the formation of acetamide could involve the bimolecular reactions: