Fluorine absorption spectra and some fluorides in condensed state

The absorption spectra of liquid F₂, NF₃, N₂F₄, CF₄, BF₃, NF₃, SF₆ have been obtained at diminished temperatures in the near ultra-violet region of the spectrum. It is shown that the absorption spectrum does not differ from the spectra in the gaseous phase, therefore the elementary absorption act is characterized by the cross section of photon absorption by an individual molecule. The absorption cross sections of the above mentioned molecules are represented in the liquid phase, which do not differ strongly from absorption cross sections of these molecules in the gaseous phase. The dependence of the absorption cross sections of liquid fluorine on its concentrations in solutions with N₂, Ar, NF₃, O₂ at - 196°C has been studied. The cross sections of photon absorption by the fluoride molecule in different liquid media with small fluorine concentrations have been obtained.     

Influence of wilt infection on the gossypol pigments of seeds and roots of a cotton plant of the variety Tashkent-1

A study has been made of the gossypol pigments of the seeds and roots of a cotton plant of the variety Tashkent-1 infected with wilt in comparison with a healthy plant. The amount of gossypol in the infected plant was lower than in the healthy plant. In the diseased plant, gossypurpurin was concentrated in the roots, and in the healthy plant it was concentrated in the seeds. Gossypol possessing optical activity was detected in the seeds and roots of both the healthy and the diseased plants.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 63–66, January–February, 1989.     

Separation of molybdenum from tungsten with di(2-ethylhexyl)-phosphoric acid ac extractant

The use of di(2-ethylhexyl)phosphoric acid (HDEHP) as an extractant for the separation of molybdenum from tungsten was examined with the help of molybdenum-99 and tungsten-187 as radiotracers. Effective separation was obtained when the aqueous phase contained phosphoric acid at pH 0.8–2 or pH 3–3.5, depending on the amounts of metal. The method is applicable to both tracer and milligram amounts of molybdenum. The structure of the extracted species was examined by infrared spectroscopy.     

Reactions of heterocyclic cations with nitrogen-containing nucleophiles. 10. Synthesis of 3,5,7-triaryl-1,2-oxazepinium perchlorates by the reaction of 2,4,6-triarylpyrylium salts with nitrones and substituted hydroxylamines

2-Substituted 3,5,7-triaryl-1,2-oxazepinium perchlorates were obtained by the reaction of 2,4,6-triarylpyrylium salts in dimethylformamide with nitrones and N-arylhydroxylamines. The products are the first representatives of seven-membered cations with eight electrons.See [1] for Communication 9.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 457–460, April, 1982.     

Autocatalytic condensation of 1,2-orthoesters of sugars with 2,3-dihydroxy-1,4-naphthoquinone (isonaphthazarin)

The autocatalytic glycosylation of isonaphthazarine and its derivatives with 1,2-orthoesters of D-glucose and maltose in chlorobenzene has been studied. It has been established that the ratio of mono- and bisglycoside forms depends on the acidity of the glycosylated hydroxy group and its steric accessibility. Free monoglycosides of 2,3-dihydroxy-1,4-naphthoquinone have been synthesized by deacetylation with sodium methoxide in methanol.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 477–482, July–August, 1989.     

Role of phosphates in the promotion of silver catalysts for partial oxidation: I. Structure and properties of phosphates on the surface of polycrystalline silver

The chemical composition, structure, and properties of an H₃PO₄-promoted polycrystalline silver foil are studied by XPS. The surface of the doped sample contains oxygen in two states with binding energies of 531.1 and 533.0 eV. Heat treatment results in silver clusters distributed in the polyphosphate matrix. It follows from TDS data that the surface of the promoted catalyst contains a strongly bound oxygen species that desorbs at ~900 K. It is believed that the silver clusters stabilized by the phosphate matrix are active sites on the surface of the phosphorus-promoted catalyst.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 153–160. Original Russian Text Copyright © 2005 by Knyazev, Boronin, Vodyankina, Koshcheev, Kurina.     

16-Demethoxymethyllycaconitine,a new norditerpenoid alkaloid from Delphinium cuneatum

A new norditerpenoid alkaloid has been isolated from the roots of Delphinium cuneatum. On the basis of ¹H, ¹³C NMR, IR, and mass spectra, the structure of the alkaloid was established as 1,6,14-trimethoxy-7,8-dihydroxy-18-(2-methyl)succinylanthranoyloxyaconane (16-demethoxymethyllycaconitine). The roots of Delphinium cuneatum also contain the known alkaloid methyllycaconitine and N,N"-di(methoxycarbonyl)-3,4-diaminotoluene.     

Mannich Condensation of exo-2,exo-6-Tricyclo[5.2.1.02,6]decan-8-one

Mannich condensation of exo-2,exo-6-tricyclo[5.2.1.02,6]decan-8-one with paraformaldehyde and dimethylamine hydrochloride results in the addition of dimethylaminomethyl fragment at the C⁹ atom to give the exo-9-isomer. The reaction of exo-9-dimethylaminomethyl-exo-2,exo-6-tricyclo[5.2.1.02,6]decan-8-one with hydroxylamine hydrochloride in alcoholic alkali yields the corresponding Z-oxime which undergoes selective rearrangement into exo-10-dimethylaminomethyl-9-aza-exo-2,exo-6-tricyclo[5.3.1.02,6]undecan-8-one by the action of sulfuric acid in acetonitrile.     

Analysis of influence of spin relaxation on form of nuclear magnetic resonance spectra in liquids with radiofrequency pumping

For a model system of two nonequivalent nuclei with spin 1/2, the NMR spectrum of one of the nuclei has been calculated under conditions of pumping of the second spin, and a study has been made of the spectral transformation upon changing the times of transverse and longitudinal relaxation of both spins. It has been established that the form of the spectrum undergoes qualitative changes. An increase in the rate of transverse relaxation not only broadens the observed lines, but simultaneously changes the character of motion of the spins in the pumping field: With increasing relaxation rate, the motion is converted from coherent motion (nutation) to incoherent motion (transitions between levels, saturation effect). Transformations of the spectrum are related specifically to these changes.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 436–443, July–August 1987.     

Photochlorination of tetramethylsilane and hexamethyldisilane in the gas phase

Preliminary studies of the reaction of chlorine with tetramethylsilane and hexamethyldisilane in the gas phase show that the photochlorination of tetramethylsilane is complex, giving different products from the corresponding reaction in solution and having an explosion boundary. At pressures below the explosion boundary the main products are ethylene, hydrogen chloride, dimethylchlorosilane, and more highly chlorinated methylsilanes. Above the explosion boundary main products after explosion are methane, acetylene, ethylene, hydrogen chloride, and silicon tetrachloride. Hexamethyldisilane reacts rapidly with chlorine in the dark, as it does in solution, forming mainly trimethylchlorosilane along with similar products to those found with tetramethylsilane. Subsequent photochlorination of trimethylchlorosilane follows a similar course to that of tetramethylsilane in the gas phase. Tentative mechanisms involving “hot” molecules are suggested.