Monazite-type monoclinic form lanthanum orthovanadate (M-type LaVO4) was synthesized by precipitating it from the mixed solution of lanthanum chloride and ammonium vanadate (V) with the mixing atomic ratio (La/V) = 1 at 20 °C in the pH 5 to 9. However, M-type LaVO4 tended to coexist with zircon-type tetragonal form lanthanum orthovanadate (Z-type LaVO4) at pHs 5–8. The single phase M-type LaVO4 was obtained only pH 9. The La/V atomic ratio obtained from the chemical analysis (ICP method) was in the range 0.99–1.01. The specific surface area and crystallite size were 250 m2/g and 22 nm, respectively. Relative density larger than 95% was achieved when the green compacts of M-LaVO4 were sintered at 1500 °C for 3 h in air.
Adsorption behavior of heavy metals on arabica and robusta roasted coffee beans treated in 5 roasting degrees was investigated. The coffee beans residue after extraction with hot water were suspended in aqueous solutions (pH = ca.6.6) containg Cu(II) or Cd(II) and the amount of heavy metal remaining in the solution was determined on an atomic absorption spectrophotometer. Adsorption ratios of Cu(II) were 60.5 and 79.6% for the light and French roasted coffee beans of Indonesia robusta employed as adsorbent, respectively. However, when the roasted coffee beans were washed with distilled water and then air-dried prior adsorption experiments, the adsorption ratios of Cu were 92.2 and 92.6%, respectively and that of Cd was 95.6 and 97.0%. Thus, the heavy metals were almost removed from aqueous solution by use of the roasted coffee beans with washing and drying treatments.
When the starting materials 4-acetyl-ONN- and -NNO-azoxybenzene(1α and 1β, respectively) were heated in 70/80% sulfuric acid, α/β isomerization and the Wallach rearrangement to 4-acetyl-4′-hydroxyazobenzene (2) were observed. However, neither the o-hydroxyazobenzene nor 4-acetyl azobenzene was detected in the reaction product. The isomerization of 1α was faster than that of 1β, demonstrating the higher themodynamic stability of the latter.
The carboxylation of m-aminophenol with potassium hydrogencarbonate in aqueous solutions has been studied kinetically. The formation of 4-hydroxyanthranilic acid (4HAA) has been found for the first time in the carboxylation of m-aminophenol which gives only p-aminosalicylic acid (pAS) in the usual Kolbe-Schmitt reaction. Since 4HAA was easily decarboxylated, the product was removed from the reaction mixture after the carboxylation for 1 h at 60 °C. This method was repeated three times and 4HAA was obtained as a major product in 30.2% yield.
A mild and convenient method for generation of nitrile oxide is established by iodosylbenzene oxidation of aldehyde oximes. Aldehyde oximes were converted to furoxans in almost quantitative yields via dimerization of corresponding nitrile oxides upon oxidation. When the oxidation was carried out in the presence of alkene and alkyne dipolarophiles, isoxazolines or isoxazoles were obtained in good yields.
Previously we reported regioselective formation of dianions derived from liner nitroalkanes in the presence of n-BuLi and HMPA. The formation of nitroalkane dianions either α,α- or α,β-dianions depended on the order of addition of reagents. However, the usage of a carcinogen suspected compound like HMPA is undesirable. Therefore we re-investigated the new combination of bases and aprotic dipolar solvents other than HMPA. After exploration of a variety of their combination, it was found that the combination of LDA and DMPU resulted in the formation of α,β-dianion with the best regioselectivity; the ratio of α- to β-adduct was 1 to 14 in the reaction of nitroethane with benzaldehyde.
Antioxidative effects of Taheebo extract, obtained from the bulk of Tabebuia avellanedae Lorents and Griseb, were examined by two assay methods for radical scavenging activity on DPPH and inhibitory effect on linoleic acid peroxidation. In the case of the DPPH method, Taheebo showed the electron donating ability to DPPH and its ability corresponded to that of trolox in the present experimantal condition. On the other hand, in the autoxidation of liloleic acid, Taheebo extract showed the most inhibitory effect in teas tested (green tea and oolong tea.). These results suggested that Taheebo extract was a desirable antioxidant.
The perovskite oxide LaCoO3 was synthesized by three different preparative methods i.e., the calcination of a mixture of La2O3 and CoO (La–Co–O) and pyrolysis of a co-precipitated precursor (La–Co–ox), La2 (C2O4)3 · xH2O + CoC2O4 · yH2O, and a heteronuclear complex (La–Co–CN), La[Co(CN)6] · 5H2O. The obtained powders were characterized by thermogravimetric analysis, infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy and specific surface area measurements. The formation of LaCoO3 single phase is clearly recognized for La–Co–O, La–Co–ox and La–Co–CN at temperatures above 1000, 1200 and 600 °C, respectively. The nano-sized LaCoO3 powder was obtained at low temperatures by pyrolysis of La–Co–CN. The mean particle diameter of La–Co–CN calcined at 600 °C for 2 h was 72 nm.