C₂H₅NO Isomers: From Acetamide to 1,2-Oxazetidine and Beyond

This work documents the properties of a number of isomers of molecular formula C₂H₅NO from the most stable, acetamide, through 1,2-oxazetidine and including even higher energy species largely of a dipolar nature. Only two of the isomers have been detected in emissions from the interstellar medium (ISM); possible further candidates are identified, and the likelihood of their being detectable is considered. In general, hardly any of these compounds have been discussed in the existing chemical literature, so this work represents an important contribution extending the canon of chemical bonding which can contribute to machine learning, providing a more exacting test of AI applications. The presence in the ISM of acetamide, CH₃C(O)NH₂, is the subject of current debate with no clear and obvious paths to its formation; it is shown that a 1,3-[H]-transfer from (E,Z)-ethanimidic acid, CH₃C(OH)═NH, is feasible in spite of an energy barrier of 130 kJ mol^-1. It is speculated that imidic acid can itself be formed from abundant precursors, H₂O and CH₃C≡N, in an acid-induced, water addition, autocatalytic reaction on water-ice grains. H₃CC≡N$$H₃CC≡NH⁺ + H₂O$$H₃CC(O⁺H₂)═NH$$H₃CC(OH)═NH + H₃O.