The acidity constants of some synthesized protonated pyrazolo quinazoline compounds were determined potentiometrically at ionic strength of 0.1 M in DMF: water (60:40 v/v) system at different temperatures (298.15 K to 318.15 K). The pKa values have been found to increase with increasing electron-donating nature of substitutions. Some thermodynamics parameters such as enthalpy (ΔH°), Gibb’s free...

Acid–base chemistry of clay minerals is central to their interfacial properties, but up to now a quantitative understanding on the surface acidity is still lacking. In this study, with first principles molecular dynamics (FPMD) based vertical energy gap technique, we calculate the acidity constants of surface groups on (010)-type edges of montmorillonite and kaolinite, which are representatives...

in this research some mathematical calculations has been explained on the “ +vo2 +glycylglycine” system and some equations has been deduced to determine the stability constants ofthe equilibrium models including mlh+, ml and ml2h species (while m+ ≡ +2 vo , h2l+ ≡protonated glycylglycine and mlh+, ml and ml2h represent the considered complexes). thecalculations are based on some relations betwe...

The acidity constants of the 2-fold protonated (1H-benzimidazol-2-yl-methyl)phosphonate, H2(Bimp)(+/-), are given, and the stability constants of the M(H;Bimp)+ and M(Bimp) complexes with the metal ions M2+ = Mg2+, Ca2+, Ba2+, Mn2+, Co2+, Cu2+, Zn2+, or Cd2+ have been determined by potentiometric pH titrations in aqueous solution at I = 0.1 M (NaNO3) and 25 degrees C. Application of previously ...

Background: Due to the adverse effects of artificial preservatives on food and its harmful effects on human health, researchers have been considering replacing these materials with natural substances. In this study, the effect of pomegranate peel extract (PPE) on the stability and antifungal activity of the walnut kernel was studied. Methods: The pomegranate peel was extracted by the solvent ...

Very strong organic acids (acid groups ionized at pH 3.0) represent a significant portion of the total acidity (4--25%) in samples of organic matter isolated from two lakes, a landfill leachate, and a Krafft mill effluent. On the basis of model compound behavior and established complexation constants, these very strongly acidic groups are predicted to be the key to the formation of strong surfa...

This work aimed to the study effect of ethanol ratios on acidity constants bromocresol purple. The BCP were determined in binary mixtures water with containing 0, 30, 40, 50, 60, and 70% (v/v) using spectrophotometric methods. results indicate dependence ratio ethanol. values log10Ka1 log10Ka2 correlated macroscopic (relative permittivity, ε) microscopic Kamlet–Taft parameters (α, β, π*) mixtur...

Ab initio molecular dynamics delivers the two thermodynamic pathways opened for reduction of CO 2 to HCOOH in aqueous media after first electron transfer and acidity constants intermediates (COOH HCOO) each pathways.