Studies of reaction of tetramethylthiourea with hydrogen peroxide: evidence of formation of tetramethylthiourea monoxide as a key intermediate of the reaction

摘要

The reaction between tetramethylthiourea (TMTU) and hydrogen peroxide was studied by UV-VIS spectroscopy, ESI mass spectrometry, H-1 NMR, cyclic voltammetry and surface-enhanced Raman scattering. We found that the reaction includes two consecutive steps, that is, (i) an oxidation of TMTU to TMTU monoxide (TMTMO) and (ii) further oxidation of TMTU monoxide to tetramethylurea (TMU) and sulfate. The second step is complex and seems to include extrusion of sulfur monoxide (SO). Density functional theory calculations were employed on tetramethylthiourea oxide models in order to underline differences between monoxide and di- and trioxides. Calculations predict that the TMTMO structure can be best explained as an adduct of thiourea with an oxygen atom (=S->O).