Computational exploration on hydroxyl and sulfate radicals-induced aqueous degradation of imipramine

In the present work, hydroxyl (•OH) and sulfate radicals (SO4•−)-induced aqueous degradation of imipramine (IMI) was theoretically probed by carrying out density functional theory (DFT) calculation. Among the initial reactions of •OH (SO4•−) toward IMI, the hydrogen abstraction (HA) reactions occurring on saturated carbon atoms of the alkylamine side chain are the most favorable, followed by the addition (AD) reactions involving unsaturated carbon positions, and the HA reactions related to unsaturated carbon atoms are the most unfavorable. The most favorable subsequent reactions for the initial AD and HA intermediates can afford the hydroxylation, oxidation, dehydrogenation, CN or CC bond cleavage products of IMI, while the corresponding ring-opening reactions occur hard. The stronger oxidizing ability of SO4•− was predicted in comparison with •OH. The cationic form of IMI has lower reactivity than IMI.H2O and O2 molecules may exert a significant influence over aqueous degradation of IMI.