Table of pKa values

The fastest and easiest way to determine the pKa is to look it up in tables of pKa values stored within the CHESS system. If no value is found there, it can be calculated using LFER1s such as the Hammett equation. Hammett rho and sigma values are stored in tables inside the CHESS system. Situations that deviate from linear additivity are noted in an exceptions table to prevent erroneous calculations. If a calculation is not possible, the user would be asked to determine the value experimentally. 

Table 4 pKa Values of Pyrrole-, Furan-, Thiophene-, Selenophene- and Tellurophene-earboxylie Aeids... 

There is a discrepancy in the literature concerning 4-hydroxy-cinnoline. Whereas two measurements of pKa values indicate that the cinnolinone structure predominates by a large factor in aqueous solution (see Table III), comparison of the ultraviolet spectra of 4-hy-... 

TABLE 2. pKa values acids in water at 25 °C of p- and m-sulfonio- and sulfonyl-benzoic ... 

TABLE 9. pKa values of various compounds in DMSO (after References 40-42)... 

Table 20 pKa values different lengths n. for convergent diacids [42] with spacers X of... 

Systematic studies of the thermodynamic and kinetic acidity of metal hydrides in acetonitrile were carried out by Norton et al. [10, 11]. A review of the acidity of metal hydrides presents extensive tabulations of pKa data [12] only a few of the trends will be mentioned here. Metal hydrides span a wide range of pKa values considering only metal carbonyl hydrides shown in Table 7.1, the range exceeds 20 pfCa units. As expected, a substantial decrease in acidity is... 

Moving further to the left along the Periodic Table in seeking the central atom of the substituent, i.e. the one by which the substituent is anchored to the heterocyclic nucleus, we expect to find that nucleus overwhelmingly in the pyridine form. Generally this turns out to be true (76AHC(Si)7i). Measurements of pKa values have been made in aqueous solution of model systems such as (234) (233) and (233) (235), from which KT may be... 

Table 1 pKa Values for the Dissociation of some Monosubstituted Pyridinium Ions and their N-Oxides... 

Gibbs energy of dissociation, table 293 pKa values of, table 293 strengths of 95-96 Acid -base catalysis 469,486 - 491 concerted 490 of mutarotation 487 Acid - base chemistry... 

Table 4 pKa Values of Azepines and their Benzo and Dibenzo Derivatives... 

Inevitably the calculation of log D relies on a knowledge of pKa values. These in turn may need to be calculated (see Section IV). Mainly because of the problems of calculating pKa, there are fewer methods to calculate log D. Some of these methods are summarized in Table 3.2. 

Table 3. pKa Values for Various Acid-Base Equilibria of Aquaplatinum Complexes (nomenclature according to Scheme 1, Y = Cl or H20)... 

Additionally, examination of pKa values in DMSO and mixtures of DMSO with hydroxylic solvents, as obtained by different methods, has revealed considerable variation. This is illustrated in Table 6 for two compounds frequently used as anchors for acidity function scales. If one is to correlate pATa values with thermodynamic transfer functions [eqn (6)], rationalize varying orders of acidity in different solvents (Table 6), or use them inBr nsted relationships (Section 3),... 

The elution profile shown in Fig. 3-4 indicates that glycine, alanine, valine, and leucine can be separated clearly by ion-exchange chromatography yet these four amino acids have almost indistinguishable sets of pKa values (Table 3.2). How can you account for this behavior ... 

Before the study of complexation, pKa values of acerands 4 and of the reference azophenol 13 were determined by spectrophotometry in 10% dioxane-water (Table 1). The table shows the increase of pKa values with decreasing crown ring size. This fact is explained by destabilization of the phenolate anion due to both the electrostatic repulsion between the phenoxide anion and the lone pair electrons of ethereal oxygen atoms and the blocking of the crown ring against solvation of the anion. 

Table 4 pKa values of pyrrole-, furan-, thiophene-, selenophene-, and telluro-phene-carboxylic acids... 

Table 11 pKa Values of selected protonic acids in organic solvents... 

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