Nitropyrazoles

The double Vilsmeier formylation of theC-methyl group in pyrazole derivatives has been shown to occur when a nitro-group is in the adjacent position of the ring. A method for the synthesis ofC-(diformylmethyl)nitropyrazoles based on this reaction has been developed.For the previous communication, see Ref. 1; for Part 2, see Ref.2 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1273–1276, July, 1993.     

Synthesis, band structure, and optical properties of Ba2ZnV2O8

A novel compound Ba₂ZnV₂O₈ has been synthesized in high temperature solution reaction and its crystal structure has been characterized by means of single crystal X-ray diffraction analysis. It crystallizes in monoclinic system and belongs to space group P2₁/c with a=7.9050(16), b=16.149(3), , β=90.49(3). It builds up from 1-D branchy chains of [ZnV₂O₈⁴⁻]_∞, and the Ba²⁺ cations are located in the space among these chains. The IR spectrum, ultraviolet-visible diffuse reflection integral spectrum and fluorescent spectra of this compound have been investigated. The calculated results of energy band structure by the density functional theory method show that the solid-state compound of Ba₂ZnV₂O₈ is an insulator with direct band gap of 3.48 eV. The calculated total and partial density of states indicate that the top valence bands are contributions from the mixings of O-2p, V-3d, and Zn-3d states and low conduction bands mostly originate from unoccupied antibonding states between the V-3d and O-2p states. The V-O bonds are mostly covalence characters and Zn-O bonds are mostly ionic interactions, and the ionic interaction strength is stronger between the Ba-O than between the Zn-O. The refractive index of n_x, n_y, and n_z is estimated to be 1.7453, 1.7469, and 1.7126, respectively, at wavelength of 1060 nm for Ba₂ZnV₂O₈ crystal.     

Determination of nanogram amounts of boron in some antimony compounds

Summary A method has been developed for determining boron in antimony compounds in the range 10^–7–10^–6%. The method comprises the isolation of the boron by distillation as methyl borate and its determination fluorimetrically with dibenzoylmethane. For the three materials analysed, SbCl₃, Sb₂O₃, and SbCl₅, individual procedures of dissolution as well as distillation were developed. The results obtained are reproducible, the mean deviation being about 12% at boron concentrations of 10^–7–10^–6%.

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Zusammenfassung Ein Verfahren zur Bestimmung von 10^–7 bis 10^–6% Bor in Antimon-verbindungen wurde ausgearbeitet. Es umfaßt die Abtrennung des Bors durch Destillation als Methylborat und dessen fluorimetrische Messung mit Dibenzoylmethan. Für SbCl₃, Sb₂O₃ und SbCl₅ wurden jeweils eigene Arbeitsweisen der Auflösung und Destillation angegeben. Die Analysenergebnisse sind reproduzierbar; die mittlere Abweichung beträgt etwa 12% für Borkonzentrationen von 10^–7 bis 10^–6%.

     

Integral intensities of the absorption bands of the skeletal vibrations of substituted furocoumarins

Conclusions The IR spectra of 5- and 8-hydroxyfurocoumarins and their esters, 5,8-disubstituted furocoumarins containing hydroxyl, methoxyl, and alkoxyl groups, and 4,5-dihydrofurocoumarins differ with respect to the intensity and number of the bands in the 1630–1500 cm^–1 region of the spectrum. The integral intensities of the absorption bands in this frequency region differ markedly in the derivatives mentioned.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 355–359, 1969     

Characterization of nickel loaded mordenite catalysts by temperature programmed reduction

Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.

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() Ni^II NiNaM NiHM. . .

     

Intramolecular "Aryl-metal chelate ring" pi,pi-interactions as structural evidence for metalloaromaticity in (aromatic alpha,alpha'-diimine)-copper(II) chelates: molecular and crystal structure of aqua(1,10-phenanthroline)(2-benzylmalonato)copper(II) three-hydrate

By reaction of Cu(2)CO(3)(OH)(2), 2-benzylmalonic acid (H(2)Bzmal), and 1,10-phenanthroline (phen), [Cu(Bzmal)(phen)(H(2)O)] x 3H(2)O (compound 1) has been obtained and characterized by thermal, spectral, magnetic, and X-ray diffraction methods. The molecular structure of 1 is remarkably similar to that of [Cu(Bzmal)(bipy)(H(2)O)] x 2H(2)O (compound 2, bipy = 2,2'-bipyridine). In both complexes, the aryl(Bzmal) ring produces an unexpected pi,pi-stacking interaction with the Cu(II)-(aromatic alpha,alpha'-diimine) chelate ring, at an average distance d(pi)(-)(pi) of 3.40 A, involving roughly parallel and smoothly slipped rings. This insight is discussed as new structural evidence for metalloaromaticity of Cu(II)-(aromatic alpha,alpha'-diimine) chelate rings. Interestingly, 1 recognizes itself by a weak intermolecular pi,pi-stacking interaction between aryl(Bzmal) ligands to give pairs of complex molecules. In contrast, there is an intermolecular pyridyl-pyridyl pi,pi-stacking interaction also forming pairs of complex molecules in 2.     

High-throughput cytochrome P450 inhibition screening via cassette probe-dosing strategy. IV. Validation of a direct injection on-line guard cartridge extraction/tandem mass spectrometry method for simultaneous CYP3A4, 2D6 and 2E1 inhibition assessment

A highly efficient direct injection on-line guard cartridge extraction/tandem mass spectrometry (DI-GCE/MS/MS) method has been validated for high-throughput evaluation of cytochrome P450 (CYP) 3A4, 2D6 and 2E1 inhibition potential via cassette dosing of midazolam, dextromethorphan and chlorzoxazone using human hepatic microsomes and 96-well microtiter plates. Microsomal incubations were terminated with formic acid, centrifuged, and the resulting supernatants were injected for analysis by DI-GCE/MS/MS. Due to the novel use of an extremely short C(18) guard cartridge (4 mm in length), this method exhibits several advantages such as no sample preparation, excellent on-line extraction, short run time (2.5 min), and minimized source contamination and performance deterioration. The DI-GCE/MS/MS method demonstrates acceptable accuracy and precision for the simultaneous quantification of 1'-hydroxymidazolam, dextrorphan and 6-hydroxychlorzoxazone in microsomal incubations. The inhibition potential of CYP3A4, 2D6 and 2E1 has been evaluated using their known selective inhibitors. The IC(50) values measured by the cassette dosing approach (high-throughput) are consistent with those observed by an individual dosing regimen (conventional) and are all in good agreement with the literature values. The results suggest that the cassette probe-dosing strategy may provide an in vitro approach to minimize cost while maximizing throughput of CYP inhibition evaluation of new chemical entities in support of drug discovery and development.     

Synthesis of thieno[3.2-<Emphasis Type="Italic">b</Emphasis>]pyrrolenine derivatives under the Fischer reaction conditions

The reaction of alkyl 4-(2-acetylhydrazino)-2-methyl-3-thiophenecarboxylates with 3-methylbutan-2-one was carried out under the Fischer reaction conditions. The influence of Lewis acids and solvents on the process was studied. A convenient method for the synthesis of thieno [3.2-b]pyrrolenine derivatives was proposed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 725–729, March, 2005.     

Automation of the gas analysis of14C-labelled compounds utilizing a piston-type counter tube

In this paper an automatic apparatus designed for the radioactivity measurement of¹⁴C-labelled organic compounds in the gaseous phase is described. The labelled organic compounds are combusted in a mixture of argon and oxygen. After combustion the oxygen content of the gas is eliminated by passing it through a copper packing. The water and heteroelements present are also removed and the radioactive carbon dioxide gas is swept by argon carrier gas into a piston-type counter tube. In the counter tube the piston forming a dividing wall moves forward in accordance with the rate of combustion and sweeping, and thus sucks the gases leaving the combustion tube into the effective tube volume. The anode wire is carried by a reel located in the piston and a spring device ensures its stretched state. At the end of the sweeping period methane is fed into the counter tube and the activity of the argon—methane—carbon dioxide mixture is measured in the limited proportional region. Manual and automatic operation is possible. The piston-type counter tube provides possibility for strandardization by means of extrapolation and for measurement of absolute activities.