Bulletin of the Chemical Society of Japan

Tanizaki, Yoshie; Hiratsuka, Hiroshi; Hoshi, Toshihiko

doi: 10.1246/bcsj.43.2283pmid: N/A

Making use of the isosbestic points which appear in equilibrium between two chemical species, the chemical structures of various species produced from the diazaazulene derivatives have been investigated in aqueous solutions over a wide pH range. For 1-hydro-1,3-diazaazulene-2-one (abbreviation, HDA-1), for instance, four different species exist as stable species in the respective regions; (a) the pH region higher than 12, (b) around the neutral state, (c) the pH value of ca. 1.5, and (d) the strong acid state. In the (a) region, H+ is taken off from the amino nitrogen of HDA-1 and the species becomes HDA-1−; in (b) the species takes the HDA-1 structure, as its name indicates; in (c) it takes the H+-HDA-1 structure protonated at the aza nitrogen, and in (d) it takes the H+-HDA-1-H+ structure, in which the position of the second protonation could not be clarified. In the case of 2-ethoxy-1,3-diazaazulene (EDA-2), the species corresponding to the second protonation (H+-EDA-2-H+) is hydrolyzed by acid catalysis and becomes H+-HDA-1-H+. In order to interpret the spectra of azaazulene compounds and the spectral change due to protonation, calculations by the LCAO–ASMO–SCF–CI method have been made for 1,3-diazaazulene and EDA-2. The characters of the first and the second transitions of the compounds have been satisfactorily explained by the diagrams of the AO coefficients of the LCAO-MO’s representative of the transitions.

Hida, Mitsuhiko; Sanuki, Teruko

doi: 10.1246/bcsj.43.2291pmid: N/A

The maximum-slope method, previously suggested by one of the authors has proved to be more advantageously applied to the determination of the aggregation constant (Kn) and the degree of aggregation (n) in a dye solution than is Zanker’s method. Changes in the spectra of the aqueous or ethanolic solutions of Rhodamine 6G, 3,6-diaminoacridine and thionine were studied as their concentration increased by means of both the maximum-slope method and Zanker’s method. The aggregation characteristics obtained by these two methods were then compared with each other and discussed.

Komoda, Ryozo; Nishi, Yasuhide; Kano, Matsutaro; Imoto, Tatsuya

doi: 10.1246/bcsj.43.2297pmid: N/A

The thermal decomposition of lead carbonate tablets was kinetically studied in a nitrogen gas stream at temperatures of 240, 320, and 360°C. The tablets used in this work were prepared by compressing lead carbonate particles in a steel mold under pressures of 2–15 ton/cm2. The decomposition reaction for the tablet was represented in two ways. Rate expressions were developed from the unreacted-core shrinking model applied to the individual particles (for the first of the two decomposition processes) and to the whole tablet (for the second). The effect of the pressure applied in preparing the tablet on the decomposition rate was attributed to the deviation in the pressure profile for carbon dioxide in a tablet (for the first process) or to the variation in the effective diffusivity and bulk density of the tablet (for the second).

Srivastava, K K; Vij, J K

doi: 10.1246/bcsj.43.2307pmid: N/A

Measurements of static dielectric constant at 1 Mc, refractive index (for sodium D-line) and complex dielectric constant at 9.44 GHz (X-band) have been made to determine the relaxation times and dipole moments of N,N′-dimethylaniline (A), N,N′-diethylaniline (B), o-chloroaniline (C), m-chloroaniline (D) and p-chloroaniline (E) in dilute solutions of non-polar solvents. Substances A, B, C and D have been studied in n-heptane, benzene decalin and Nujol. The measurements for A and B have also been extended to cyclohexane, whereas E has only been studied in benzene. The values of relaxation time, calculated by Higasi’s equations in terms of a0, a′, a″ and a∞, and those of α, calculated from Cole-Cole’s equation in terms of the same parameters, showed an evidence for the existence of more than one relaxation mechanism. This has been interpreted in terms of the intramolecular rotations of the amino (or the substituted amino) group occurring simultaneously with the overall molecular orientation.

Vij, J T; Srivastava, K K

doi: 10.1246/bcsj.43.2313pmid: N/A

Measurements of dielectric constant and loss have been made at 1 Mc and 9.44 GHz for dibutyl ether and benzophenone in various solvents, e.g., n-heptane, benzene, cyclohexane, carbon tetrachloride, decalin and Nujol. Whereas, diphenyl ether has only been studied in benzene and cyclohexane. The values of relaxation time and distribution parameter have been determined by using Cole-Cole’s equation in terms of the so-called slopes, a0, a′, a″ and a∞. The relaxation time values show a regular increase with the increase in viscosity of the medium both for dibutyl ether and benzophenone. The observations seem to suggest that dibutyl ether relaxes both by molecular and intramolecular mechanisms. The dipole moments in various solvents have also been calculated.

Yoshioka, Takashi

doi: 10.1246/bcsj.43.2317pmid: N/A

A new crystal phase with a kalsilite-type structure has been found in devitrified glass with compositions close to CaAl2O4 on the CaAl2O4-SiO2 join. The crystal can be synthesized as a nearly pure phase by heating the glass for 5 to 20 min at 1000°C. After prolonged heating, the crystal easily decomposes into an assemblage of the stable compounds, CaAl2O4, CaAl4O7, and Ca2Al2SiO7(gehlenite). Most of the X-ray powder diffraction lines of the kalsilite-type phase can be indexed on the basis of a hexagonal unit cell with a=5.0 Å and c=8.1 Å. In addition to these reflections, some weak ones which cannot be indexed on the basis of this unit cell are also present. The kalsilite-type phase reacts with water, resulting in heat liberation and hardening.

Kobayashi, Hiroshi; Shimizu, Masayuki; Kaizu, Youkoh

doi: 10.1246/bcsj.43.2321pmid: N/A

Magnetic circular dichroism (MGD) of [Fe(CN)6]3− was measured in aqueous solution and in a polyvinylalcohol film. The use of the polyvinylalcohol (PVA) film made it possible to measure the MCD and the absorption spectrum of an electrolyte such as K3[Fe(CN)6] at dry ice - methanol and liquid nitrogen temperatures, since the film was still optically transparent at lower temperatures. From a comparison between the observations at 300°K, 195°K and 77°K, the magnitude of an angular momentum due to the orbital motion of a hole in the ground state 2T2g (t2g5) was calculated to be 0.04–0.07 Bohr magneton (β). The observed reduction of the angular momentum was interpreted to be due to partial quenching of the orbital motion by the Jahn-Teller distortion, and also to the delocalization effect between the iron dπ orbital and the antibonding π molecular orbitals of the coordinating CN− ions. The B term in [Fe(CN)6]3−, which had been ignored, was predicted to be non-zero and was estimated as −2.4×10−3 β/cm−1 at the band I and 0.97×10−3 β/cm−1 at the band II.

Iwadare, Yoshio; Suzawa, Toshiro

doi: 10.1246/bcsj.43.2326pmid: N/A

In order to investigate the adsorption behavior of an anionic surfactant on fibers, the ζ-potentials of natural and synthetic fibers in aqueous solutions of sodium dodecyl sulfate (SDS), mainly above the critical micelle concentration (CMC), were measured. Further, the change in the structure of the SDS micelle in aqueous solutions was studied by means of the viscosity method. At first the reduced viscosity for the SDS micelle, ηspm/cm (cm: the micellar concentration), increased rapidly with the cm as long as the cm was small; thereafter, after a break, it approximated the saturated values as a whole. The results calculated from the experimental data using Jones and Dole’s equation showed two distinct breaks. The first break corresponded to the 1st CMC, and the second, nearly to the break in the ηspm/cm  vs.  cm curve. In addition, the intrinsic viscosity for the SDS micelle, [η]M, and the effective specific volume, V, were obtained. From these results, it can be assumed that the structure of the SDS micelle is variable at the break in the ηspm/cm  vs.  cm curve. The ζ-potentials of fibers in aqueous SDS solutions changed rapidly with an increase in the concentration of SDS, but they remained approximately constant in the vicinity of the CMC. At much higher concentrations above the CMC (in the vicinity of the SDS concentration of 2×10−2 mol/l), the ζ values again gradually changed; thereafter, after a break, they became nearly constant again. The change in the ζ-potentials corresponds approximately to the break in the ηspm/cm  vs.  cm curve. Therefore, it may be suggested that it is connected with the change in the structure of the SDS micelle.

Yamashita, Shigeru; Adachi, Kin-ichi; Hayakawa, Teruo

doi: 10.1246/bcsj.43.2332pmid: N/A

Benzene-photosensitized decomposition of nitrous oxide has been studied in a mercury-free reaction system. 2537 Å line of low-pressure mercury lamp was absorbed by benzene and the excitation energy of benzene was transferred to nitrous oxide by triplet-triplet energy transfer mechanism. Only N–O bond rupture of nitrous oxide has been observed, which is reasonable from energetic view point. The decomposition yield of the excited triplet state of nitrous oxide was estimated to be 15% and the triplet state seems to be less than 84 kcal/mol above the ground state.

Kobayashi, Hiroshi; Shimizu, Masayuki; Fujita, Ichiro

doi: 10.1246/bcsj.43.2335pmid: N/A

The magnetic circular dichroism of iron tetraphenylporphins was measured. Since the ground state of the open-shell iron porphin is degenerate and several charge-transfer excited states exist near the 1Q and 1B states, the A term as well as the B and C terms are very important for describing the MCD of the iron porphin, whereas the MCD at the 1Q and 1B bands, which arise from the pure degenerate (π,π*) excitations in D4h porphin assumed for zinc tetraphenylporphin, is ascribed to the A term. The MCD of carboxyhemoglobin, oxyhemoglobin and also deoxyhemologin was observed and compared with that of the synthesized iron porphins.