Reaction pathway and kinetic study of 4,5-dihydroxyimidazolidine-2-thione synthesis by HPLC and NMR

Process of 4,5-dihydroxyimidazolidine-2-thione (DHIT) synthesis from thiourea and glyoxal is studied. Formation of imidazole-2-thiones and 4,5-dihydroxyimidazolidin-2-one as byproducts is confirmed by NMR. The kinetics of the scalable DHIT synthesis process is studied by HPLC, and the kinetic parameters of the model based on the proposed reaction scheme are calculated. The model correctly describes the kinetics of the DHIT formation and thiourea consumption

The Study of Structural Features of N- and O-Derivatives of 4,5-Dihydroxyimidazolidine-2-Thione by NMR Spectroscopy and Quantum Chemical Calculations

In the present work, the new N-methylol and O-alkyl derivatives of 4,5-dihydroxyimidazolidine-2-thione (DHIT) are synthesized. The effects of N-alkyl, N-phenyl, N-methylol, and O-alkyl substituents of DHIT on the 13C and 1H signals in NMR spectra of the imidazolidine-2-thione ring are systematized using quantum chemical calculations. The shift values of carbon and hydrogen atoms are specific for the geometric isomers of the indicated DHIT derivatives. The chemical shifts of the carbon atoms of the methine groups allows for identifying the cis and trans isomers of the N-alkyl derivatives of DHIT due to the up-field shifts of the cis isomers. The introduction of an alkyl substituent at the N-position of the imidazolidine-2-thione ring leads to the up-field shifts of the carbon atoms of the ring due to the inductive effects of these groups. The ring current effect in the N-phenyl derivatives of DHIT that affects the positions of the carbon signals of the imidazolidine-2-thione ring has been found. The N-methylol derivatives of 4,5-dihydroxyimidazolidine-2-thione have been identified for the first time using 1D and 2D NMR