C2H4NO

C2H4NO is a molecular formula that denotes a composition of two carbon atoms, four hydrogen atoms, one nitrogen atom, and one oxygen atom. Its nominal molar mass is about 58.06 g/mol. As a formula alone, it does not specify a unique structure; a variety of constitutional isomers would be possible if the molecule were a neutral, closed-shell species.

In practice, applying the standard degree of unsaturation calculation to C2H4NO yields a value of 1.5, which is not an integer. For a neutral, closed-shell organic molecule, the degree of unsaturation must be an integer. This implies that there is no stable neutral compound with this exact formula under ordinary bonding patterns. If a species with this composition is detected, it is typically in a charged state, a radical, or as a transient fragment, rather than a conventional neutral molecule.

Because of this, C2H4NO is most often encountered in analytical contexts as an empirical or nominal formula rather than a single, well-defined compound. It can arise as a subformula in mass spectrometry data or as a constraint in formula-generation exercises, where additional structural information—such as connectivity, charge, or functional groups—is required to identify a specific isomer. Without such information, the formula alone does not uniquely determine a structure.