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Inuzuka, K\={o}z\={o}; Yokota, Toshio
doi: 10.1246/bcsj.38.1055pmid: N/A
The state energies, charge densities, bond orders and free valences of benzaldehyde have been elucidated by the use of the SCF-MO method with a model of Cs symmetry, including interactions of all the singly-excited configurations. In the singlet state, the numerical values of state energies are more reliable than the previous results, which were derived from the C2v model by the use of Hückel MO. In the triplet state, however, the numerical values of state energies seem to be lower than the previous results.
Nagata, Kyoichi; Umayahara, Akira; Tsuchiya, Ryokichi
doi: 10.1246/bcsj.38.1059pmid: N/A
The formation constants of chromium(III) complexes with the oxalate ion, which is the simplest bidentate ligand coordinating by two oxygen atoms, have been determined by the pH method.It has been shown that the formation constants of oxalato chromium(III) complexes are larger than those of the corresponding titanium-(III) complexes, but smaller than those of the corresponding manganese(III), iron(III) and cobalt(III) complexes in the first transition series.The formation constants of oxalato chromium(III) complexes have been found to be remarkably smaller than those of the ethylenediamine chromium(III) complexes. This result suggests that two nitrogen atoms form a more stable complex with chromium than do the two oxygen atoms serving as donors in the bidentate chelate.
doi: 10.1246/bcsj.38.1071pmid: N/A
The reaction between Ag+ and VO3− ions has been investigated by means of electro-metric techniques involving amperometric, potentiometric and glass electrode titrations between silver nitrate and Na2O·V2O5 in 40% alcoholic media. The end point obtained from the sharp breaks and inflections in the titration curves, occurs at a stage where the molecular ratio of Ag+ and VO3− ions is 1:1 and corresponds to the formation and precipitation of silver metavanadate, Ag2O·V2O5, in the pH range 6.25–7.0. Amperometric titrations yield very accurate results and offer a simple and rapid method of determining vanadium (V) as silver metavanadate.
doi: 10.1246/bcsj.38.1074pmid: N/A
The jackfruit pectic acid has been converted into ethylene glycol ester, which, on reduction with sodium borohydride, gives a galactan. Methylation studies of the original polysaccharide and of the reduced pectic acid suggest the presence of chains of 1→4 linked α-d-galacturonic acid residues in the pectic acid which is associated with a glucan.
doi: 10.1246/bcsj.38.1077pmid: N/A
The polysaccharide isolated from the mesocarp of unripe mango has been found to be a mixture of three component polysaccharides, viz., a glucan, and araban and a galacturonan. By a methylation study, the glucan has been found to have the same structural pattern as that of the glucan isolated from ripe mango. The araban portion yielded 2,3,5-, 2,3- and 2-O-methyl-l-arabinose. On the basis of these results, a probable structure has been assigned to the araban. The isolation of only 2,3-di-O-methyl-d-galacturonic acid shows that the galacturonan portion is 1→4 linked.
Kameyama, Haru; Urakami, Chieko
doi: 10.1246/bcsj.38.1081pmid: N/A
Reduction of egg yolk lecithins with lithum aluminium hydride under the following reaction conditions resulted in release of choline in about 50% based on the total water-soluble phosphorus; mole ratios of lecithin: lithium aluminium hydride of 1 : 10 or 1 : 15 at 10–15°C for 60–120min. were used. Unexpectedly, the reaction did not give any glycerylphos-phoric acid. Instead, the analytical results indicated that a phosphorus-oxygen fission of the cholin-phosphate linkage is accompanied by reduction of the phosphate moiety.
doi: 10.1246/bcsj.38.1086pmid: N/A
4-Nitro-1-hydroxy-1,2,3-benzotriazole (R) has been used as a reagent for the gravimetric estimation of silver. The precipitation of the metal by this reagent is complete between pH 2.8–4.3, and after drying at 120°C the composition of the precipitate corresponds to the formula AgC6H3O3N4. The presence of other metal ions does not interfere in the estimation. For complete precipitation of the metal, double the stoichiometrically required amount of R was used and it was found that variation of the interval between the precipitation and filteration does not effect the result. The solubility of R is 0.2134 g./100 g. of water at 30°C.
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