γ-Pyrone derivatives fromHalenia corniculata
From 500 g of the epigeal part of Halenia corniculata (L.) Cornaz., collected in the Pribaikal region of the Buryat ASSR in July 1975, by extraction with 70% ethanol followed by treatment with chloroform we have isolated 32.7 g of extractive substances. Chromatography of the chloroform extract on silica gel with elution by chloroform yielded substances (i) and (2) of xanthone nature, and chloroform-ethanol (9:1) yielded luteolin, which was identified by its UV, mass, and PMR spectra and by comparison with an authentic sample [i].
Xanthones of the Gentianaceae—II : Frasera albicaulis Dougl. ex Griesb.
Abstract The root of Frasera albicaulis Dougl. ex Griesb. has been shown to contain fifteen xanthones, ten of which are previously unreported in nature. These compounds have been identified spectroscopically and in most cases by comparison with synthetic samples. They are shown to be based on the 1,3,5- and 1,3,7-trioxyxanthone systems with added oxygen atoms at 2 and/or 4, and represent a number of methylation patterns including 1,3-dihydroxy, 1-hydroxy, 2-hydroxy, and totally methylated materials.
Chemical Metallurgy: Principles and Practice
Foreword. Preface. Acknowledgements. Appreciation. 1. Acquaintance. 2. Mineral Processing. 3. Thermodynamics and Kinetics. 4. Pyrometallurgy. 5. Hydrometallurgy. 6. Electrometallurgy. 7. Energy and Environment. Subject Index.