The prototropic exchange equilibria of two drugs, nizatidine (I) and ranitidine(II), and also of structurally related the N,N'-dimethyl-2-nitro-1,1-ethenediamine molecule (III) were investigated. From the changes in electronic spectra in media of various acidity several protonation constants were determined. For pK values were -0.82, 1.95, and 6.67; for ranitidine pK values were 1.95 and 8.13; ...

The purpose of this work was to synthesize and characterize the thiatetraaza macrocycle 1-thia-4,7,10,13-tetraazacyclopentadecane ([15]aneN4S). Its acid-base behaviour was studied by potentiometry at 25 °C and ionic strength 0.10 M in KNO3. The protonation sequence of this ligand was investigated by 1H-NMR titration that also allowed the determination of protonation constants in D2O. Binding st...

The existence of protonated hydroxymethylamines of sec+ ondary amines, RzNHCHtOH, in equilibrium with hydroxymethylamines and protonated amines, has been demonstrated by titration at equilibrium and by rapid titration of the protonated hydroxymethylamines. Analogous compounds, . R3NCHeOH, are formed from formaldehyde and the sterically favorable tertiary amines: pyridine, iv-methylimidazole, an...

The existence of protonated hydroxymethylamines of sec+ ondary amines, RzNHCHtOH, in equilibrium with hydroxymethylamines and protonated amines, has been demonstrated by titration at equilibrium and by rapid titration of the protonated hydroxymethylamines. Analogous compounds, . R3NCHeOH, are formed from formaldehyde and the sterically favorable tertiary amines: pyridine, iv-methylimidazole, an...

in the crystal structure of the title polymeric compound, [c42h38n6o33sr5.2(h2o)]n, five independent metal atoms (sr1-sr5) have different coordination environments. the sr1 and sr5 atoms are nine coordinated and feature distorted tricapped trigonal-prismatic and capped square-antiprismatic geometries, respectively. the rest srii atoms have eight coordination numbers. these units are connected v...

the dependence on ionic strength of protonation of glycine and its complexation with dioxouranium (vi) is reported in sodium perchlorate and sodium chloride solutions as background salts. the measurements have been performed at 25±0.1°c and various ionic strengths in the range 0.1 to 1.0 mol , using a combination of potentiometric and spectrophotometric techniques. the overall analysis  of the ...

Abstract The preparation 0f azo dyes is the subject of this research. 4-hydroxycoumarin with each ofo-amino benzoic acid (3-[o-Amino acidazo]-4-hydroxycoumarin]) (B 1 ) and Sulfa guanidine (3-[Sulfa azo]-4-hydroxycoumarin) 2 were syntheses. Azo compounds characterized by I.R, CHN, H-NMR Elctronic Mass spectroscopy. At various pH levels, electronic spectra these investigated in terms acid-base p...

The determination of formation constants of binary inner transition metal complexes where M=Y(III) or La(III) or Ce(III) or Pr(III) or Nd(III) or Sm (III) or Gd (III) or Dy (III) or Th(IV) andL = Creatinine have been carried out using Irving–Rossotti titration technique in aqueous mediaat different temperatures and at ionic strength. To understand more about the nature ofequilibrium involving i...

In the crystal structure of the title polymeric compound, [C42H38N6O33Sr5.2(H2O)]n, five independent metal atoms (Sr1-Sr5) have different coordination environments. The Sr1 and Sr5 atoms are nine coordinated and feature distorted tricapped trigonal-prismatic and capped square-antiprismatic geometries, respectively....