Mechanisms of interstellar synthesis of glycine, alanine, and serine from aminonitriles, OH, and H₂O

A new potential energy surface for forming glycine in the gas phase, starting from association of aminoacetonitrile (NH 2 CH 2 CN) with OH followed by subsequent hydrolysis, was determined using CBS‐QB3 calculation. The overall activation energy was 90 kJ mol −1 or 0 without or with catalytic H 2 O, respectively. Alanine or serine was formed from 2‐aminopropionitrile (CH 3 CH(NH 2 )CN) or 2‐amino‐3‐hydrxypropionitrile (HOCH 2 CH(NH 2 )CN) instead of aminoacetonitrile with the overall activation energies of 89 or 49 kJ mol −1 , respectively. When an additional H 2 O was involved in each reaction as a catalyst, barrierless reaction pathways were obtained. These results suggest that it is possible for investigated reactions to occur in interstellar ices along the proposed pathways, taking kinetic aspects into account.