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1. Absorption spectra of benzidine disazo dyes and their copper derivatives in aqueous solution were measured at room temperature, and they are compared with one another.2. It was shown by a simple calculation that the dyes, each of which has sulfonic groups adjacent to the azo groups, have strained conformations caused by the repulsion between the sulfonic groups and the unshared electrons of nitrogen. It was also shown that the relationship between the relative positions of sulfonic groups to the azo groups and the relative absorption intensities could well be explained.3. The absorption intensities of the copper derivatives were nearly equal, having no relation to the positions of the sulfonic groups, and in addition they were near to those of the non-copper dyes which have the sulfonic groups adjacent to the azo groups. Hence, it was pointed out that the introduction of copper caused the same extent of strain in conjugated systems as sulfonic groups did.

1) The absorption spectra of some naphthalene sulfonic acid derivatives have been determined in various pH solutions.2) The remarkable spectral change revealed by the variation in pH value can be interpreted in terms of the process of the proton association and dissociation of the functional groups.3) The pH region in which the process takes place is characteristic of the kinds, –NH2, –OH, and the number of the functional groups and their locations on the naphthalene skeleton.4) The relative pH regions have been explained in outline by taking into account the effects of the sulfonic group, the intramolecular hydrogen bond formed between the functional groups, and the resonance of the functional group to the link.5) The band assignment concerning the transition direction of the derivatives has been decided; the first and the second band correspond, respectively, to the 1Laand 1Bbof naphthalene.6) The order of the magnitude of the substitution effect has been clarified as –NH3+< –OH<–NH2<–O-.

1) The amount of dyes adsorbed by Cellophane from two mixture dyeings of Chlorazol Sky Blue FF and Chrysophenine G, and Chlorazol Sky Blue FF and p-nitroaniline ?? acid (a-coupling) was measured. Further, the amount in case of single dyeing was also measured.2) It was assumed that the reduction in adsorption of dyes from mixture dyeing is due to an interaction between the two dyes in the dyebath, and that this interaction means only the formation of complexes. On this assumption, the instability constant in the case of the pair of Blue dye and Yellow dye was calculated, according to the mass action law, but it was impossible to calculate it in the case of the pair of Acid dye and Blue dye, because the composition of complexes of this pair was not constant.3) How the amount of Blue dye adsorbed from mixture dyeing varies with the sort and the concentration of its partner dye and with the dyeing temperature was discussed from the standpoint of the instability constant and the affinity.

1. The absorption spectra of the dyes prepared by coupling disazotized 2S-, H-, chromotropic, NW-, ?- and J- acid with dianisidine, and of their copper derivatives were observed in aqueous solutions of the binary mixture with Chrysophenine G, and were compared with the sum curves of the component absorption spectra.2. The order of the equilibrium constants for a 1:1 complex formed between the dyes not containing copper and Chrysophenine G was parallel to the respective values of the difference in wave number (?? cm-1) between maximum positions in the region of 390~420 mµ of the curve simply added and that observed with the equimolar binary mixture of about 1×10-5mol./1.; it was also parallel to those of the decreasing ratio in optical density (?D/D) of the mixed system at the first maximum position of the sum curve.3. Under the same conditions as above, ?? and ?D/Dwere also determined for the mixture of the copper derivatives and Chrysophenine G. In this case, the copper derivatives of 2S-, H-, and chromotropic acid, in the presence of effective auxochromes, still revealed large values of ?? (ca. 1000 cm-1) and ?D/D(ca. 15%), while the values for the rest of the derivatives were almost zero.4. Discussing the above results, it was shown that in order to display a spectral change due to the formation of a 1:1 complex in a binary mixture with Chrysophenine G, it is necessary that the partner dye has effective auxochromes (amino, hydroxyl) as terminal groups of a conjugated system. It was also shown that the sulfonic groups which are attached to the terminal naphthalene nuclei act on the structure of the dye itself as a steric factor rather than as an electric effect (repulsion) between the ionic charges in the groups and those of Chrysophenine G, and that the more planar structure, resulting in a smaller steric effect, produces more complex.

1. The change in absorption spectra of mixtures of Chlorazol Sky Blue FF and Chrysophenine G in aqueous solution was stoichio-metrically studied in detail and a 1:1 complex and a 1:2 complex were proved to be formed.2. The absorption spectra of the complexes were drawn from experimental results by use of the calculated equilibrium constants, and the phenomena of these absorptions were qualitatively explained according to VB and MO methods, with the conclusion that charge transfer spectra from Chlorazol Sky Blue FF to Chrysophenine G appear in the complexes.

The conductances of aqueous solutions of Chlorazol Sky Blue FF (Blue), Chrysophenine G (Yellow), Sodium Chloride and their binary mixtures at various constant ratios have been measures. The conductance observed with a mixture of Blue and yellow increased abnormally compared with that obtained by the sum of individual dye conductances; the difference between the observed and the sum values reached a maximum at about the same fraction of the equivalent concentration of component dyes. A similar relation of the conductance against the fraction of the conductance against the fraction of the equivalent concentration of components, obtained with mixture, in which component dye was substituted by sodium chloride. did not always show a coincidence between the observed value and the sum one. the difference, however was much smaller than that obtained with dye mixtures. Thus, the abnormal increase described above may be attributed to the formation of complexes of Blue and Yellow; a 1:1 complex and a 1:2 complex, consisting of Blue and yellow already known, were sufficiently reflected in the conductance curve, especially in the conductance curve, especially in a 1:2 complex.

1. The absorption spectra of the binary mixtures in aqueous solution of Chlorazol Sky Blue FF and sulfanilic acid → cresidine and sulfanilic acid → cresidine→ cresidine were measured at room temperature.2. The mixture of Chlorazol Sky Blue FF and sulfanilic acid → cresidine shows the additive spectrum when the ratio of the two dyes is about 1:5 but the non-additive one when it is about 1:40. From this fact the authors pointed out that even if an equimolar or nearly equimolar mixture shows the additive spectrum, it often exhibits the additive one with a relative increase of one component, due to the interaction between the components. That the spectra of the mixture pass through an isosbestic point means that a Sky Blue molecule interacts with nmolecules of sulfanilic acid → cresidine (nis unknown).3. It was indicated that the mixture of Chlorazol Sky Blue FF and sulfanilic acid → cresidine→ cresidine showed the non-additive spectrum, and that this was well explained by assuming the formation of a 1:1 complex over the range of concentrations measured.4. The authors discussed qualitatively the characters of the spectra and the stability of these complexes, comparing them with the complex of Sky Blue and Chrysophenine G, etc.

1. The change in spectrum at 620 mμ of the mixture of Chlorazol Sky Blue FF and p-nitroaniline→γ acid in aqueous solution was measured in detail at room temperature, by varying the concentration of the component dyes.2. On the assumption that the spectral change is due to the complex formation, the composition of complexes was discussed by comparing the observed and the calculated difference in optical density.3. It may be supposed that a 1:1 complex occurs to a great extent over a range of low concentration of p-nitroaniline→γ acid as compared with that of Chlorazol Sky Blue FF, and that higher complexes are formed in the presence of an excess of the acid dye.

1. Absorption spectra of mixtures of Direct Sky Blue 6B with p-X-aniline → γ acid, in which the substituent X means H, CH3, OCH3, Cl or NO2, and the components in aqueous solution were observed in the visible and near ultraviolet regions.2. All the absorption bands showed non-additive property, excepting the bands in the region of 400∼460 mμ of the mixtures of Sky Blue and X-β shown in Figs. 2 and 3. And optical densities of observed bands of a mixture were generally smaller than sums of the values of each component, but when the acid dyes made by α coupling were used as other components, increases were seen at the positions corresponding to wave lengths of the first bands of them.3. An explanation for these non-additive properties was given by means of the interaction between the corresponding bands of components.4. At the same time, in this connection, it is pointed out that the apparent single band of the first of p-X-aniline → γ acid in α coupling consists of two bands and similarly the first band of Direct Sky Blue 6B may also consist of two bands.

1) The absorption spectra of binary mixtures of Chrysophenine G (notation: G) and disazo dyes (P), which were the same as those used in a preceding study,1)have been measured at room temperature (ca. 20°C), and the characteristic spectra of the complexes have been determined by using the equilibrium constants, K1and K2, previously obtained (at 20°C) for the 1 : 1 (PG) and 1 : 2 (PG2) complex formation.2) The absorption spectra of the PG and PG2complex have been compared with the respective corresponding additive spectra (P+G and P+2G), and the correlations among these spectra have been discussed in detail.3) The MO pattern of the G molecule has been decided empirically by applying Platt’s theory; similarly, that of the P molecule has been decided by assuming that there is at least one symmetry species; then the spectral change caused by the complex formation could be explained in relation to the MO’s of the component molecules.4) It has been confirmed that there exists an intermolecular charge transfer from P as an electron donor to G as an acceptor. It has also been shown that the first band of a disazo dye (P) consists of two electronic transitions; one is a π→π*(shorter wavelength) and the other an l→π*transition (longer wavelength).

1) Using five kinds of dyes of Sky Blue FF and of similar structures, the equilibrium constants for a 1 : 1 and a 1 : 2 complex formed with Chrysophenine G have been determined by means of spectroscopy in the intervals of 20–60°C.2) A new method of calculating the equilibrium constant has been proposed.3) The free energy change (−ΔF), the enthalpy change (−ΔH) and the entropy change (−ΔS) for the complex formation have been obtained.4) The correlation between these quantities and the chemical structure has been discussed and the following facts clarified: The larger the number of effective auxochromes (NH2, OH), the greater –ΔHand −ΔSbecome. The sulfonic group contributes to −ΔSthrough the location of that group. The dye molecule in the complex state is more planar than in the free state.