In the absence of comprehensive chemical kinetic mechanisms for the formation of species in the interstellar medium, including the key compound acetamide, it is difficult to propose routes to the candidate C 2 H 5 NO molecules. Given that acetamide is present in high abundance it is not unreasonable to look at this as a possible source and then it can be noted that simple H-atom transfer reactions, Fig. , link acetamide to 1-amino ethenol and to (E,Z ) ethanimidic acid, Fig. , whilst the reasonably abundant (Z ) rotamer of N-methyl formamide is linked to (E,Z ) N-methyl formimidic acid, Fig. .