Reductive alkylation of thioureas: a highly practical synthesis of unsymmetrical N,N′-disubstituted thioureas

A highly practical synthesis of unsymmetrical N,N′-disubstituted thioureas by the reductive alkylation of N-monosubstituted thioureas with aldehydes is described. N-Monosubstituted thioureas can in turn be synthesized by the reductive amination of thiourea with an appropriate aldehyde. This reductive alkylation methodology was also extended to carbamates.     

14N and 13C NMR of tautomeric systems of hydroxy-pyridines

¹⁴N NMR is shown to be an efficient method of investigation of the tautomeric equilibria in hydroxy-and related substituted pyridines. Large relative ¹⁴N chemical shifts within tautomeric pairs estimated from N-Me and O-Me derivatives make possible quantitative determinations of the equilibria. Qualitative conclusions may be drawn from ¹⁴N line widths as well as from ¹³C and proton chemical shifts.     

119Sn NMR Spectra of Some Carbohydrate Organotin Derivatives

Abstract

The ¹¹⁹Sn NMR spectra of several sugar-tin derivatives were recorded. The geometric and steric isomers of all of the organotin derivatives studied were easily differentiated by ¹¹⁹Sn NMR. The appropriate ¹¹⁹Sn resonances are: ca - 50 ppm for trans and ?60 ppm for cis vinyltin derivatives (1-3), ca 16 ppm for allyltins 4-6, and ca ?32 ppm for tin-carbinols 9 and 11. When the hydroxyl group in carbinol 9 was converted to an O-acetyl group, the chemical shift of ¹¹⁹Sn was shifted to ?22 ppm.     

Polarity and Conformations of Phosphazacompounds in Solution

Abstract

A series of iminophosphoranes o-X-C₆H₄-N=PPh₃, where X=H(I),Me (II),Et (III),OMe(IV),OEt(V) were investigated by means of dipole moments method. Because of an orientation of aromatic fragment determines intramolecular interactions in the system (benzene ring - double N=P bond), the problem of internal rotation of N-C_ar bond is important. DM (exp.) of molecules (I-V), determined in dioxane are 4.30(I), 4.34(II), 4.53(III), 4.75(IV), 4.79 D(V), respectively.     

Photochemical Synthesis of N4-Substituted Cytosines

The convenient method for the preparation of N⁴-substituted cytosines is described. The irradiation with UV light of N-(1H-2-oxo-4-pyrimidinyl) amino acids provides the proper N⁴-substituted cytosines in a good yield.     

Standardization of 177Lu by means of 4π(LS)β-γ coincidence and anti-coincidence counting

Journal of Radioanalytical and Nuclear Chemistry - The activity concentration of a 177Lu solution was measured by the Laboratory of Radioactivity Standards in the Radioisotope Centre POLATOM. The...     

Standardization of 90Y solution by mean of a Cherenkov counting in comparison with a liquid scintillation counting technique

Journal of Radioanalytical and Nuclear Chemistry - This paper presents the standardization of 90Y solution using the Cherenkov method measuring in the TDCR counters. The counting efficiencies for...