A Theoretical Investigation of OH• + H2CCNH Reactivity: Interstellar Insights into Glycolonitrile Formation

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.