Dissociation constants (pK, 20°C) of D-galacturonic acid, D-glucuronic acid, their O-methyl derivatives, as well as of the corresponding 4,5-unsaturated substance have been determined by means of discontinuous Potentiometrie titration. The found pK values have been interpreted from the point of view of inductive and mesomeric effects, and nonbonding interactions. It is demonstrated that the eff...

The complexation of Cd2+ by diallyl disulfide (DADS) and diallyl sulfide (DAS) has been studied by differential pulse voltammetry. Stability constants, (log β), of the 1:1 (PbL) and 1:2 (PbL2) complexes, where L = ligand, were found to be in the range of ca. 5.8 - 6.2 and 9.6 -10.6, respectively. Complex formation is accompanied with a significant decrease in the peak current and the shift of t...

the complexation reactions of some transition metal ions and 2-aminopyridine (2-ampy) were studied potentiometrically in aqueous solution at µ=0.1 m and 25 °c. the overall stability constants log β’s of all species are obtained by computer refinement of ph-volume data with using the best computer program. several models were tested and the best one accepted according to the least sum of squared...

Effects of temperature and percentage of organic modifier were studied on retention and selectivity in RP-HPLC using solvation parameter model. The system constants were determined by multiple linear regression analysis from experimental values in the retention factor for a group of different solutes with known descriptors by computer using the program SPSS/PC. The experimental results showed t...

The acidity constants (pKa) of thirty four (34) ;-substituted carboxylic acids in aqueous solution havebeen calculated using conductor-like polarizable continuum (C-PCM) solvation model. The gasphaseenergies at the Density Functional Theory (DFT-MPW1PW91) and solvation energies atHartree Fock (HF) are combined to estimate the pKa values which are very close to the experimentalvalues where, and ...

effects of temperature and percentage of organic modifier were studied on retention and selectivity in rp-hplc using solvation parameter model. the system constants were determined by multiple linear regression analysis from experimental values in the retention factor for a group of different solutes with known descriptors by computer using the program spss/pc. the experimental results showed t...

In this work, we investigated the stability of Molybdate-Phosphonic Acid (MPA) complex by density functionaltheory (DFT) computations in six solvents with the dielectric constant ranging from 1.92 to 10.36. The methodsare used for calculations are B3LYP and B3PW9 I that have been studied in two series of basis sets: D95nand6-31+G (d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphoru...