Abstract
In order to vary the distance of positive and negative charge centers, Δr, dicarboxylic acids were titrated with KOCH3 and R4NOH (R=CH3, C2H5, n-C4H9), as well as with LiOCH3 and NaOCH3. With tetramethylammonium hydroxide (TMAH), Dc value of numerous acids was obtained but less with tetraethylammonium hydroxide (TEAR), and not at all with tetrabutylammonium hydroxide (TBAH). As shown in Table I, values of Dc obtained with R4NOH are much smaller than those obtained with alkali. It is suggested from the data shown by equations (1) and (2), and in Table II, that the values of Δr TMAH and TEAH should be markedly large or small, and the values calculated from equation (3), based on the data in Table III, are 0.76 and 0.62 Å, respectively, being very small. This seems reasonable from the fact that, when titrated with two kinds of bases with different Δr, values of Dc found were in good agreement with the values calculated from equation (4) and Fig. 2. The reason for this seems to be the displacement of charge center of R4N+, or a large overall dissociation constants of R4N salts, rather than the solvation of alkali ions (Table V).
For the estimation of r, Δr values of 2.35, 2.73, and 0.76 should respectively be adopted for NaOCH3, KOCH3 and TMAH, TMAH is especially useful since its salts are all soluble.
