The structure of xanthalin

Conclusions From the roots ofXanthogalum purpurascens growing in the Transcaucasus, we have isolated a new coumarin, C₂₄H₂₆O₇ with mp 111–113°C, [] _D ²⁰ –164.2° (c 0.97; ethanol) which we have called xanthalin. On the basis of the NMR spectrum it has been established that xanthalin is 3, 4-diangeloyl-2, 2-dimethyl-3, 4-dihydropyrano-5, 6:6, 7-coumarin.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 5, pp. 280–283, 1968     

The effect of methyl substituents on the properties of ions and radicals formed from propenyl- and isopropenyltoluenes

The Hückel MO method and the heteroatomic model for substituents have been used to calculate the quantum chemical properties of ions and radicals formed from the isomeric tolylpropenes. By comparing the calculated values between themselves and with the analogous quantities for phenylpropyl ions and radicals an estimate is made of the additional perturbation caused by the introduction of a substituent. The most favorable perturbations for substitution in the nucleus are observed in the ortho- and para-positions of the cations.     

Ultraviolet absorption of flavonoids. V. The structure of 3- and 5-hydroxyflavones

Summary 1. The peculiarities of the properties of 3-hydroxyflavone are due to the fact that the introduction of the proton-donating hydroxy group directly into the heterocycle leads to an increase in the aromaticity of the pyrone fragment through the stabilization of a pyrylium structure.2. The causes of the decreased acidity and basicity of 5-hydroxyflavone are the formation of an intramolecular hydrogen bond of the chelate type and a disturbance of the coplanarity of the molecule. The combination of these factors explains the anomalously high position of the band of the stretching vibrations of the carbonyl group of this compound.Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 583–587, September–October, 1975.     

Neodymium ethylenediaminedisuccinates

Conclusions Using high-resolution spectrography the authors have shown that in the system ethylenediaminedisuccinate-neodymium (III) chloride there are formed two forms of unprotonized monocomplexonates of the same composition but differing in the number of donor atoms of the ligand cordinated with the central neodymium ion. One of the forms of neodymium monoethylenediaminedisuccinate contains free donor groups and can therefore form polynuclear complexes with the aquo ions of neodymium introduced into the solution.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1431–1435, July, 1979.     

Investigation of the coumarins and furocoumarins ofHippomarathrum caspium (DC.) Grossh.

Summary 1. Osthole, oxypeucedanin, heraclenin, and oxypeucedanin hydrate have been isolated from the roots ofHippomarathrum caspium (DC) Grossh. and identified; the presence of traces of isoimperatorin, imperatorin, and umbelliferone has been established chromatographically. A substance with mp 149–150° apparently belonging to the sitosterol group has been obtained.2. Xanthotoxin has been isolated from the leaves and stems; the presence of a small amount of bergaptene and umbelliferone has been detected chromatographically.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 5, pp. 356–359, 1965     

Thermal and thermo-oxidative degradation of polystyrene in the presence of bromine-containing flame retardants

The kinetic of thermal and thermo-oxidative degradation of polystyrene in the presence of bromine-containing flame retardants was investigated. It was shown that the kinetics is limited by diffusion in air and by the processes occurring at the interface in helium.The flame retardants affect the degradation of polystyrene both chemically and physically, and change the mechanism of the limiting stage to some extent.

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Zusammenfassung Die Kinetik des thermischen und thermo-oxidativen Abbaus von Polystyren in Gegenwart bromhaltiger Flammschutzmittel wurde untersucht. Es wird gezeigt, dass die Reaktion durch die Diffusion in Luft bzw. durch die Grenzflächenvorgänge in Helium begrenzt wird.Die Flammschutzmittel beeinflussen den Abbau von Polystyren sowohl chemisch als auch physikalisch und verändern im gewissen Masse auch den Mechanismus des geschwindigkeitsbestimmenden Schritts.

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Reaction of cyclopentadienyllutetium anthracenide with azobenzene. Synthesis and molecular and crystal structure of the binuclear complex [C5H5(THF)Lu(μ−η2:η2−PhN—NPh)]2(THF)2 and its dynamic behavior in solution

The reaction of the cyclopentadienyllutetium anthracenide, C₅H₅Lu(C₁₄H₁₀)²⁻(THF)₂ (1), with azobenzene yielded the [C₅H₅(THF)Lu(μ−η²:η²−PhN—NPh)]₂(THF)₂ (2) binuclear complex. The structure of the reaction product was established by X-ray structural analysis. The dynamic behavior of complex2 in a THF-d₈ solution was studied by¹H NMR spectroscopy in the temperature range of 265–330 K. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1667–1671, September, 1997.     

1.5-Diaza-3.7-diphospha-cyclooctane

The alkyl (aryl)-bishydroxymethylphosphines react with primary amines to give the title compounds. With optically active amines optically active phosphines are formed.     

An in vitro Study on Transition from NO-Hemoglobin to Methemoglobin： Oxygen Effect

The nitrosyl-hemoglobin (HbNO) is the carrier of nitric oxide (NO) which is the important messenger molecule displaying multiple physiologic and pathophysiologic roles. However it is still not clear for the fate of HbNO molecules during the venous-arterial transit. In this letter, the HbNO transition in vitro was studied by using the electron paramagnetic resonance (EPR) spectra. It was found that HbNO molecules were stable when oxygen did not exist in the system but not stable in aerobic conditions. The absorption spectra further revealed that the methemoglobin (metHb) was the product of HbNO in aerobic environment, showing that the HbNO changed to metHb when there were enough oxygen molecules in the system.     

Reactions on a surface. 1. Condensation of 3-methyl-3-buten-1-ol with carbonyl compounds on SiO2 and Al2O3

3-Methyl-3-buten-1-ol reacts with various aldehydes and ketones on silica gel and Al₂O₃ surfaces in the absence of solvents and conventional catalysts for this reaction to form derivatives of di- and tetrahydropyrans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1326–1328, October, 1989.