The ionization constants of typical acids and bases

Abstract

values calculated by each method, It was shown that AKOH at any pH was equal to a function containing the hydrogen and hydroxide ion concentrations, dissociation constants, the stoichiometric concentrations of ligand and acid, and the concentration of potassium hydroxide in the ligand-metal titration.Comparison of A values calculated by the two methods gives a check on the validity of the data and for the concentration of ligand.It was pointed out that calculations for tetracycline analogs a t a high pH would be inaccurate since a dissociable hydrogen on a complexed molecule, but remote from the site of coordination, will have a larger dissociation constant than the same hydrogen on a free ligand.The thermodynamic dissociation and stoichiometric stability constants were calculated for five tetracycline analogs with cupric ion and these values were compared with the data of previous workers. Contrary to the conclusions of Doluisio and Martin, the biologically inactive analogs, 4-epi-chlortetracycline and 4-epi-anhydrotetracycline, were found to form 2: 1 complexes, which were quite insoluble and which precipitated a t W values just above 1. 987Methods for the calculations of the biligand stability constants were discussed. -. N THE FIRST paper of this series (1) on simula-

Specific features of sorption kinetics of heavy metal ions with polysaccharide materials from aqueous media

“…are in a good agreement with pK a of carbonic acids having OH-group in α-position (рК а(СООН) 3,71-3,83) [49], and also with literature data for cellulose containing materials (рК а(СООН) 4,0) [44].…”

Acid-base interactions in some isoquinoline and quinazoline amino derivatives

“…24 Aminoquinazolines were prepared from Narylbenzamides or N-phenyl-N',N'-diethylureas in the reaction with PCl 5 and then with N,Ndimethylcyanamide or cyanamide in the presence of TiCl 4 . [25][26][27][28][29][30] The determination of the pK a dissociation constants was performed according to the spectrophotometric method 31 of Albert and Serjeant in 50% aqueous methanol solution (10 -5 M, room temperature) due to the low solubility of the compounds in water and characteristic UV spectrum (Table 1, 3,4). Absorption maxima of the isoquinoline and quinazoline ions were selected as analytical wavelengths, bearing in mind their considerable shifts relative to the maxima of the non-protonated forms.…”

Contribution of Substituent Groups to the Extractability of Phenols and Benzoic Acids

“…These are in good agreement with those obtained in aqueous solutions. 5 The values of log KD of phenol, 2-naphthol and benzoic acid were obtained from both the horizontal lines and calculations using Eq. (1): they were 0.44, 1.91 and 0.46, respectively.…”