O-acylated flavonoid glycosides of the needles ofPinus sylvestris I. O-acetylated derivatives of flavonol glycosides

Summary O-Acetylated flavonol glycosides have been isolated for the first time from the needles of the Scotch pine and the following structures have been established for them: 3,45,7-tetrahydroxy-3-methoxyflavone 3-O--D-(6-O-acetylglucopyranoside), 3,4,5,7-tetrahydroxy-3-methoxyflavone 3-O--D-(6-O-acetylgalactopyranoside), and 3,3,4,5,7-pentahydroxyflavone 3-O--D-(6-O-acetylglucopyranoside). The first two compounds have not previously been described in the literature.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. I. M. Sechenov I Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 193–196, March–April, 1978.     

Infrared study of the interaction of nitric oxide with CuY zeolites

Infrared studies of the interaction of NO with CuY–A zelites have been made over the temperature range from –100°C to 400°C. Several forms of NO adsorption have been found, in particular, a stable cis-dimer at low temperatures.

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- (–100+400°C) NO CuY–A . NO, ë - .

     

Determination of the absolute configuration of carbohydrate components of flavonol glycosides of the chestnut

Conclusions On the basis of the rates of their acid hydrolysis, their optical activities, and their IR spectra, it has been established that the glycosides ofAesculus hippocastanum L. are (SK-1) 3--L-arabofuranosyloxy-5,7,4-trihydroxyflavone, (SK-2) 3--L-rhamnofuranosyloxy-5,7,4-trihydroxyflavone, (SK-3) 3--L-arabofuranosyloxy-5,7,3,4-tetrahydroxyflavone, and (SK-4) 3--L-rhamnofuranosyloxy-5,7,3,4-tetrahydroxyflavone.The glycoside SK-3 is identical with avicularin isolated from the leaves ofPsidium quajava [5]. The complete structures of the other three glycosides have been established for the first time.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 1, pp. 5–7, 1969     

Electrochemical Determination of 4-Nitrophenol Using a Single-Wall Carbon Nanotube Film-Coated Glassy Carbon Electrode

A single-wall carbon nanotubes (SWNT) film coated glassy carbon electrode (GCE) was fabricated for the direct determination of 4-nitrophenol (4-NP). The electrochemical behaviors of 4-NP at the SWNT-film coated GCE were examined. In 0.1M phosphate buffer with a pH of 5.0, 4-NP yields a very sensitive and well-defined reduction peak at the SWNT-modified GCE. It is found that the SWNT film exhibits obvious electrocatalytic activity towards the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. The reduction peak current varies linearly with the concentration of 4-NP ranging from 1×10^–8 to 5×10^–6M, and the detection limit is 2.5×10^–9M after 3min of open-circuit accumulation. The relative standard deviation at 2×10^–7M 4-NP was about 6% (n=10), suggesting excellent reproducibility. This new method was successfully employed to determine 4-NP in several lake water samples.     

Cardenolide glycosides ofCheiranthus allioni. XV. Glucocheiranthoside

Another new cardenolide glycoside has been isolated from the plantCheiranthus allioni Hort., and has been named glucocheiranthoside. Its chemical structure has been established as 3-(4-O--D-glucopyranosyl--D-gulmoethylpyranosyloxy)-14-hydroxy-19-oxo-5,14-card-20(22)-enolide.State Scientific Center for Drugs, Ukraine, 310085, Kharkov, USSR. ul. Astronomicheskaya, 33. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 269–271, March–April, 1994.     

X-ray studies of supported copper-aluminium catalysts

Structural peculiarities of the formation of copper-aluminium catalysts at copper concentrations <10 wt% and calcination temperatures of 573–1173 K have been studied.

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<10% . 573–1173°K.

     

Flavonoids of Ammothamnus lehmannii. Structure of lehmannin and of ammothamnidin

The new flavanon lehmannin (I) has been isolated from the roots ofAmmothamnus lehmannii Bunge. On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that compound (I) has the structure of 2,4,7-trihydroxy-8-(2-isopropenyl-5-methylhex-4-enyl)flavanone. The alkaline cleavage of lehmannin gave ammothamnidin (V). The structure proposed previously for the chalcone ammothamnidin has been corrected. It has been shown that it has the structure of 2,2-4,4-tetrahydroxy-3-(2-isopropenyl-5-methylhex-4- enyl)chalcone. A comparative study of the¹³C NMR spectra of a number of flavanones has revealed an empirical law permitting the prediction of the presence or absence of substituents (OH and OCH₃) at C-2 from the value of the chemical shift of the signal of the C-2 carbon atom.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. I. P. Pavlov Samarkand State Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–524, July–August, 1987.     

A bifunctional stopcock-winch device in cells for infrared investigations of solids

A simple glass device is described acting as stopcock and winch at the same time. The device is especially suitable for the dislocation of solid sample holders in IR cells.

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, . .

     

New method for determination of the equilibrium state in systems involving reactions of the type A(s)=B(s)+C(g)

A static method is described for measurement of the equilibrium values of temperature, pressure and composition of the solid phase, and determination of the number of degrees of freedom in heterogeneous systems containing a gaseous phase, including water vapour. With this method, it has been found that in the system formed in the thermal dehydration of CaC₂O₄·H₂O a solid solution of monohydrate and anhydride coexists in equilibrium with water vapour. The composition of the solid solution changes with the temperature and the pressure of water vapour. The dehydration enthalpy of the solid solution referred to 1 mol H₂O does not depend on its composition. It was found to be H _deh=(69+-3) kJ·mol^–1.

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Zusammenfassung Eine isotherme Methode zur Messung von Temperatur, Druck und Zusammensetzung der festen Phase im Gleichgewicht und zur Bestimmung der Anzahl der Freiheitsgrade in heterogen Systemen mit einer Gasphase (z.B. Wasserdampf) wird beschrieben. Mit dieser Methode wurde nachgewiesen, dass bei der thermischen Entwässerung von CaC₂O₄·H₂O eine feste Lösung von Monohydrat und Anhydrid im Gleichgewicht mit Wasserdampf existiert. Die Zusammensetzung dieser festen Lösung ändert sich mit der Temperatur und dem Wasserdampfdruck, ihre Dehydratationsenthalpie (pro 1 mol Wasser) hängt nicht von der Zusammensetzung ab und wurde zu H _deh=(69±3) kJ mol^–1 bestimmt.

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, , , , . , , ₂₄·₂ . . , 1 , H .=69±3 .^–1.