The surface acidic property of Nb2O5·nH2O and its catalytic activities for the isomerization of 1-butene, the polymerization of propylene and the dehydration of 2-butanol were examined. The activities were high on Nb2O5·nH2O evacuated at moderate temperatures(100–150 °C) in all of the reactions and decreased drastically on evacuation at higher temperatures (400–500 °C). The surface of Nb2O5·nH2O showed a strong acidic character (H0≤−5.6) even after heating in air at 100 °C, but the strong acid sites disappeared on heat treatment at higher temperatures. The active sites on the catalysts heat-treated at moderate temperatures were ascribed mainly to Brönsted acid sites on the basis of the IR study of adsorbed pyridine.

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The niobic acids calcined at moderate temperatures of 120–300 °C showed high catalytic activities (52–75% conv. in 1 h) and selectivities (100%) for the esterification at reaction temperatures of 120–160 °C. No catalyst deactivation was observed even after the use for 60 h. The niobic acid catalysts were more effective than cation exchange resin, SiO2–Al2O3, HZSM-5, and solid super acids such as ZrO2–SO42−, TiO2–SO42−, and Fe2O3–SO42−.

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From the fruits of Phaleria macrocarpa, icariside C(3) (1), phalerin (2), and mangiferin (3) were isolated and their structures were identified on the basis of spectroscopic data. Icariside C(3) (1) showed a slow vasorelaxant activity against noradrenaline-induced contraction of isolated rat aorta. The structure of phalerin (2) was revised as 2,4',6-trihydroxy-4-methoxybenzophenone-2-O-beta-D-glucoside.

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