Abstract:
Urea (carbamide) is the main end product of amino acids' metabolism in mammals. Extensive research in the
field of urea chemistry has contributed to the creation of many biologically active and other compounds based
on the carbamide fragment NH–CO–NH. The substituting groups of urea directly affect its properties and
characteristics which are reflected in the NMR spectral data and this circumstance can be the basis for the
identification of urea derivatives. In this work, chemical shifts in the NMR spectra of urea and its acyclic
structure, barbituric series, imidazolidinone series and bicyclic structure derivatives were studied and identified. A system analysis was carried out to determine the effect of the type of substituents on the positions of
signals of the NH-CO-NH fragment in the NMR spectra. The possibility of 2D NMR spectroscopy using to
simplify the identification procedure for complex mixtures was shown in the paper. The combined use of 1D
and 2D NMR spectroscopy is convenient and informative to establish the structure of biologically active
compounds. These methods make it possible to determine the presence and type of impurities, as well as to
establish the destruction processes leading to the corresponding impurities.
