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

ABSTRACT

The reaction between tetramethylthiourea (TMTU) and hydrogen peroxide was studied by UV–VIS spectroscopy, ESI mass spectrometry, ¹H 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).

GRAPHICAL ABSTRACT

KEYWORDS:

• Thiourea oxides
• tetramethylthiourea monoxide
• hydrogen peroxide
• oxidation
• density functional theory

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Russian Foundation for Basic Research, project 16-03-00162 (to S.V.M.). Computational resources were provided by the high-performance computational facility of the Babeş-Bolyai University (MADECIP, POSCCE, COD SMIS 48801/1862) co-financed by the European Regional Development Fund of the European Union.