2023MNRAS.524.4037I

Due to the relatively high abundance of hydrogen radicals in the interstellar medium, the H-addition reaction of unsaturated organic molecules in the solid phase and at very low temperatures is considered to play an important role in the chemical complexity of organic substances in the Universe. However, when interacting with hydrogen atoms, all unsaturated functional groups that may be present in several organic species exhibit different behaviours that can significantly alter the reaction pathways from one species to another. By coupling FTIR spectroscopy and temperature programmed desorption mass spectrometry, we have investigated the H + c-C₃H₂O (cyclopropenone) solid-state reaction using two different experimental methods. We show that cyclopropenone reacts with hydrogen atoms under interstellar medium conditions, leading to propynal (HCCCHO), propadienone (CH₂CCO), and two thermodynamically most stable isomers of c-C₃H₂O. In excess of H atoms, the hydrogenation of cyclopropenone also leads to propenal (CH₂CHCHO), propanal (CH₃CH₂CHO), c-C₃H₄O (cyclopropanone), in addition to two alcohols, namely cyclopropanol (c-C₃H₆O) and propanol (CH₃CH₂CH₂OH).