EDITOR'S NOTE: This month Astromolecule of the Month opens a new category of molecule: species that are plausibly present in one or more types of astrophysical sources but have not yet been sought (in contrast to non-detections, which have been sought unsuccessfully). Watch for the "Plausible Species" graphic in the upper right corner. Molecules may fall in this category due to difficuly forming them and/or measuring suitable spectra for them or due to lack of imagination.

Carbamic acid (NH₂COOH) is a close cousin of amino acids. The only difference between carbamic acid and the first amino acid found in biology, glycine, is a –CH₂– linkage between the amino (–NH₂) and carboxylic acid (–COOH) groups. It would seem to be a reasonable species to find in space, since related molecules like formamide (NH₂CHO) and formic acid (HCOOH) with the same functional groups are well-known.

The search for carbamic acid has been impeded by difficulty forming it in the gas phase and measuring its rotational spectrum. It has been formed in both zwitterionic and neutral forms in ices beginning with a study from 1999 by Khanna & Moore and as recently as 2023 by Marks and co-workers. Marks et al. observed carbamic acid in the gas phase after forming it in ice and extracting it with photoionization relectron time-of-flight mass spectrometry. Bates and co-workers recently explored the feasibility of forming carbamic acid directly in the gas phase by a direct insertion of ¹D excited state oxygen atoms into NH₂CHO.