A general, non-energetic formation route to carboxylic and fatty acids in the interstellar medium

Carboxylic acids have been detected in the interstellar medium, and biologically relevant fatty acids have been identified on meteorites. However, their formation routes under interstellar conditions and possible delivery to planetary surfaces to act as molecular building blocks for the origin of life remain poorly understood. Here we demonstrate a general, non-energetic, condensed-phase formation route to carboxylic acids under astrophysical, low-temperature conditions, through the interaction of aldehydes and either O-atoms or hydroxyl radicals. This general acid formation route was investigated and confirmed experimentally through the use of infrared spectroscopy and mass spectrometry, and theoretically through the use of hybrid density functional theory and coupled cluster calculations. The finding of a non-energetic formation route from aldehydes to acids and the pathway to form biologically relevant fatty acids under interstellar conditions indicates that such molecules could form and subsequently be inherited into stellar systems, thus potentially contributing to the origin of life.