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Theoretical Study of the Photochemical Oxidation Mechanism of S-Containing Organical Compounds in Presence of Nitrocompounds
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1  Lobachevsky State University of Nizhni Novgorod

Abstract: Nitrocompounds in the triplet states have the biradical structure, with both unpaired electrons localized on the oxygen atoms. The structure is able to participate in oxidation reactions by the radical mechanisms. We have also proposed that some molecules can catalyze the nitrocompound destruction with N=O molecules formation. We have chosen the S-containing organic compounds like H2S, MeSH, and Me2S as substrates for oxidations in the presence of nitrocompounds. We performed theoretical quantum chemical studies of the most possible reaction mechanisms of the oxidation reactions using DFT B3LYP 6-311G++(d) method from the Gaussian 03 program package. We calculated the PES profiles, including intermediates and transition state structures. The activation energies of all stages involved were calculated.  We was able to show that MeSH molecule could dissociate to break the S-H bond. The hydrogen atoms formed immidiately find them to be added to the nitrocompound molecules. During further transformation H-atom could be abstracted from the methyl groups to form the S=C double bond. In the case of Me2S there are no hydrohen atoms that can be easily abstracted, and oxygen atom of nitrocompound attacks the S atom to form Me2SO has place. The last compound is able to abstract H-atom from the nitrocompound molecule and decompose to give Me2S and OH radical.
Keywords: quantum chemistry, nitrocompound, S-containing organical compound, DFT, transition state