C2H5NO Isomers: from Acetamide to1,2-Oxazetidine and Beyond

14 December 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


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 identifi ed and the likelihood of their being detectable are considered. In general hardly any of these compounds have featured 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 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. It is speculated that the imidic acid can itself be formed from abundant precursors, H2O and CH3C{{{N, in an acid-induced, water addition, auto-catalytic reaction on water-ice grains.


computational chemistry
formation enthalpies
ionisation energies
dipole moments

Supplementary materials

Supporting Information: C2H5NO Isomers
Cartesian coordinates, frequencies, rotational constants


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