2025ApJ...993..179F

Glycolonitrile (HOCH₂CN) has been a molecule of long-standing interest in astrochemistry. While its production on interstellar icy grains has been explored theoretically and experimentally, little is known about its gas-phase formation. In this work, we investigate the reaction mechanism of OH^• + H₂CCNH (ketenimine). We examine different orientations of OH^• relative to H₂CCNH, and report three chemically distinct reaction channels for the radical addition of OH^• along the heavy atom chain of ketenimine (either at the C(1) carbon, C(2) carbon, or N). Contrary to reported literature, our calculations reveal that several different routes to gauche- and trans-glycolonitrile are possible, and that formation proceeds in a step-wise fashion through H-atom beta-scission. With energetics evaluated using the HEAT-like protocol, a sub-kilocalorie-per-mole accuracy is expected. Therefore, rate constants (incorporating anharmonic effects) yield important insights into the molecular evolution of the title reaction and the overall fate of glycolonitrile under interstellar conditions.