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Synthesis and the 13C NMR Spectra of N,N -Disubstituted Benzoylthioureas and Their Seleno and Oxo Analogues

J. Imrich, T. Bušová, P. Kristian, and J. Džara

Department of Organic Chemistry, Faculty of Natural Sciences, P. J. Šafárik University, SK-041 67 Košice

 

Abstract: The influence of substituents on the 13C NMR chemical shift values of the aromatic ring carbons and -CO-NH-C(=X)- groups (X = S, Se, O) of a series of 27 N-benzoyl-N'-(Y-aryl)- and -N'-alkylthioureas, selenoureas, ureas, thiourethanes and isothioureas was investigated. As found, the substituents in N-benzoyl-N'-(4-Y-phenyl)thio(seleno)ureas do not considerably influence the 13C NMR chemical shifts of C=X and C=O carbons; the marked substituent effect is observed for the aromatic ring carbons only. This conclusion was also confirmed by correlations with χs and σp+ constants of substituents. Differences between the benzoyl δ(CO) values of N'-monosubstituted and N',N'-disubstituted thioureas indicate the existence of an intramolecular hydrogen bond in the acylthiourea grouping, namely between the benzoyl CO and the N'H groups. The 13C NMR chemical shift values of C=Se carbons in N-benzoyl-N'-(4-Y-phenyl)selenoureas are higher than those of the analogous C=S carbons of the corresponding thioureas. The 13C spectral chemical shift increments ∆ δ of -NHCSNHCOPh and -NHCSeNHCOPh groupings on the benzene ring were calculated.

Full paper in Portable Document Format: 481a42.pdf

 

Chemical Papers 48 (1) 42–46 (1994)

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