Complex polarizability as used to analyze dielectric relaxation measurements

The effect of representing dielectric properties in terms of the complex polarizability ^c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.     

Nitration,amination, and halogenation of Di-O-methylphloracetophenone

Chlorination of the title compound gave 5- and 3-chloro-2-hydroxy-4,6-dimethoxyacetophenone. The nitration of its acetate, followed successively by reduction, diazotization, and reaction with cuprous chloride, gave the 3-substituted series, 2-acetoxy-4,6-dimethoxy-3-nitroacetophenone, 3-amino-2-hydroxy-4,6-dimethoxyacetophenone, and 3-chloro-2-hydroxy-4,6-methoxyacetophenone, respectively. The orientation of substituents in the products was proved. The amino and chloro members of the isomeric 5-substituted series were availablevia 2-hydroxy-4,6-dimethoxy-5-phenylazoacetophenone, the product of the reaction of the title compound with benzenediazonium chloride.

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Nitrierung, Aminierung und Halogenierung von Di-O-methylphloracetophenon

Zusammenfassung Chlorierung der Titelverbindung gab 5- und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Nitrierung des Acetats, gefolgt von Reduktion, Diazotierung und Reaktion mit CuCl ergab die 3-substituierte Reihe: 2-Acetoxy-4,6-dimethoxy-3-nitroacetophenon, 3-Amino-2-hydroxy-4,6-dimethoxyacetophenon und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Orientierung der Substituenten wird diskutiert. Die Amino- und Chlorderivate der isomeren 5-substituierten Reihe sind über 2-Hydroxy-4,6-dimethoxy-5-phenylacetophenon zugängig, dem Produkt der Reaktion der Titelverbindung mit Phenyldiazoniumchlorid.

     

Dielectric properties of moist CaCO3 filled polyethylene composites

The capacitance and the dielectric loss tangents of CaCO₃ filled polyethylene composites were studied. Composite samples, prepared by polymerizing ethylene on the surfaces of fillers, pre-treated by polymerization catalysts, were compared to normal mechanical mixtures. Dielectric dispersion,, and loss, , proved to be sensitive to heating or vacuum treatment. Investigation of samples under conditions of different relative humidities showed that the dielectric dispersion is due to adsorbed water. Both and increased with decreasing frequency and the ratio of loss and dispersion was nearly constant. Dielectric data measured at different relative humidities could be represented by a single Cole-Cole plot. Samples soaked in water for different periods yielded qualitatively similar but quantitatively different Cole-Cole plots. Composite samples showed higher losses at similar humidities.Possible interpretations in terms of a molecular relaxation model, an interfacial relaxation model, including a charged double layer mechanism, percolation theory and the universal response theory were examined, but none was able to fully explain the observed phenomena.     

Untersuchung des Zerfalls verschiedener Azoinitiatoren in Lösung

The decomposition of various symmetric and unsymmetric azo-initiators (1,1-dichloro-1,1-diphenyl-1,1-azoethane, 2,2-dichloro-2,2-azopropane, 1,1-dichloro-1,1-azocyclohexane, 2,2-diacetoxy-2,2-azopropane, 1,1-diacetoxy-1,1-diphenyl-1,1-azoethane, 1,1-diacetoxy-1,1-azocyclohexane, 2,2-dipropionoxy-2,2-azopropane, 2,2-dicapronoxy-2,2-azopropane, 4,4-dimethyl-1,4-azobutyrolactone, azoisobutyronitrile, 2-t-butylazo-2-cyanobutan, 2-t-bytylazo-1-cyanocyclohexan) in solution was studied in dependence of temperature. Volumetry and differential-scanning-calorimetry (DSC) were used to determine decomposition rates; first order kinetics was found in all cases.

     

1,2-bis(2',6'-dimethyl-i',3'-dioxa-6'-aza-2'-silacyclooctyl-2')ethane and the corresponding ethylene and acetylene derivatives

Conclusions The reaction of 1,2-bis(methyldimethoxysilyl)ethane and the corresponding ethylene and acetylene derivatives with bis(2-hydroxyethyl)methylamine gives 1,2-bis(2,6-dimethyl-1,3-dioxa-6-aza-2-silacyclooctyl-2)ethane and the corresponding ethylene and acetylene derivatives. Analogously, 1,2-bis(vinyldimethoxysilyl)acetylene gave 1,2-bis(2-vinyl-6-methyl-1,3-dioxa-6-aza-2-silacyclooctyl-2)acetylene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1420–1421, June, 1988.     

Five-membered 2,3-dioxo heterocycles: XLIX. Reaction of methyl 1-aryl-3-aroyl-4,5-dioxo-4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrrole-2-carboxylates with N-substituted 3-amino-5,5-dimethyl-2-cyclohexenones

Methyl 1-aryl-3-aroyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates react with N-substituted 3-amino-5,5-dimethyl-2-cyclohexenones to give 4-hydroxy-1-aryl-3-aroyl-6,6-dimethyl-1, 2,3,4,5,5,6,7-octahydro-1H,2H-indole-3-spiro-2-pyrrole-2,4,5-triones. The structure of the products was proved by the X-ray diffraction data for the 1-cyclohexyl derivative.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 12, 2004, pp. 1840–1845.Original Russian Text Copyright © 2004 by Bannikova, Maslivets, Aliev.For communication XLVIII, see [1].     

The frozen solution E.P.R. spectrum of the bis(2,2′:6′,2″-terpyridyl)copper(II) cation

Summary A quite anomalous signal, found in the frozen solution e.p.r. spectrum of bis(2,2 6,2-terpyridyl)copper(II) is presented, discussed and ascribed to overlap between an Isotropic and an anisotropic spectrum. At liquid helium temperature the isotropic spectrum disappears and the entire anisotropic signal can be seen without interference. Dynamic Jahn-Teller effects are invoked to account for this behaviour. The experimental data are compared with those associated with analogous systems containing 2,2-bipyridyl and 1,10-phenanthroline ligands.     

Coumarins of Smyrniopsis aucheri

Chemical transformations and spectral characteristics have enabled us to establish the structure and configurations of three coumarins: (+)-2,2-dimethyl-3-hydroxy-3,4-dihydropyrano(5,6:6,7)coumarin (I); (+)-4-hydroxy-5-(1-hydroxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)coumarin (II); and (+)-4-hydroxy-5-(1-glucopyranosyloxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)-coumarin (III) isolated from the roots ofSmyrnopsis aucheri Karjag. This is the first time that these compounds, which have been called smyrinol, smyrindiol, and smyrindioloside, have been detected in nature.Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Azerbaidzhan State University, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 36–40, January–February, 1992.     

Kinetic analysis of thermogravimetric data,VI

The basic hypotheses of methods used for deriving kinetic parameters from TG data are discussed. The erroneous character of the methods which use more than a single TG curve is shown by comparing the shapes of ideal and real TG curves. The correctness of three integral methods is tested on ideal TG curves. The physical significance of the kinetic parameters and their correlation are discussed.

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Zusammenfassung Die Grundhypothesen der zur Ableitung kinetischer Parameter aus TG-Daten verwendeten Methoden werden erörtert. Der fehlerhafte Charakter der Methoden, welche mehr als eine einzige TG-Kurve verwenden, wird durch den Vergleich der Formen idealer und realer TG-Kurven veranschaulicht. Die Richtigkeit dreier Integralmethoden wird an idealen TG-Kurven geprüft. Die physikalische Bedeutung kinetischer Parameter und ihre Korrelation werden erläutert.

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Résumé On discute les hypothèses de base des méthodes utilisées pour déduire les paramètres cinétiques des données TG. Le caractère erroné des méthodes utilisant plus d'une courbe TG est mis en évidence en comparant les formes idéales et réelles des courbes TG. Le degré d'exactitude de 3 méthodes intégrales est examiné sur des courbes TG idéales. On discute la signification physique des paramètres cinétiques et leur corrélation.

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Cobalt(II) and nickel(II) chloride and bromide complexes of 2-(2′-methyl-8′-quinolyl)benzoxazole and 2-(2′ or 4′-methyl 8′-quinolyl)benzimidazole

Summary Cobalt(II) and nickel(II) halide complexes of the ligands 2-(2-methyl-8-quinolyl)benzoxazole (mqbo), 2-(2-methyl8quinolyl)benzimidazole (mqbi) and 2-(4-methyl-8-quinolyl)benzimidazole (mqbi) were synthesized and characterized by analytical, thermogravimetric, conductivity and magnetic data, and i.r. and electronic spectra.The ligands are bidentate N-donors yielding complexes where the coordination geometry depends on the metal ion and steric hindrance. All the cobalt complexes have formula [CoL₂X₂] and distorted tetrahedral geometry. Different types of nickel compounds were obtained: i) complexes of formula NiLX₂ · n H₂O (or EtOH) (L = mqbo or mqbi; n=0–1.5) which arepseudo-tetrahedral or five-coordinate and ii) complexes NiL₂X₂ · n H₂O (L = mqbi, n=3 or 4) where the metal is bound to four nitrogen atoms and the overall coordination geometry is tetragonal. The structural changes occurring after removal of water or alcohol from the complexes are also reported.     

Structure of ursinoic acid and ursinin

Conclusions On the basis of UV, IR, and NMR spectroscopy, and the preparation of derivatives, the most probable structures of ursinoic acid and ursinin, aromatic oxo acids isolated previously from the roots ofAngelica ursina Rupr. et Schmalh., have been established. It has been shown that the former has the structure 2,2-dimethylpyrano-5, 6:5, 6-(2, 4-dimethoxy)benzoylacetic acid while the second is 2,2-dimethylpyrano-5,6:5, 6-(2-methoxy)benzoylacetic acid.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 4, pp. 421–424, 1970     

Study of furan compounds

Research on synthesis of polycyclic spirans of the 1, 6-dioxaspiro-[4, 4]nonane group is continued. Electrolysis of methanol solutions of 2-furylcyclopentanol, 2-(5-methyl-furfuryl)cyclopentanol, and 2-furfuryl-1-indanol, gives, by intramolecular alkoxylation, spiro{perhydrocyclopenta[b]furan-2, 2-(5dihydrofuran)}, spiro{perhydrocyclopenta[b]furan-2, 2-(5-methoxy-5-methyl-2, 5-dihydrofuran)}, and spiro{2, 3, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-(5-methoxy-2, 5-dihydrofuran)}, hitherto undescribed in the literature. Depending on the conditions, catalytic hydrogenation of these gives: spiro{perhydiocyclopenta[b]furan-2, 2-(5-methoxytetrahydrofuran)}, spiro{2, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-(5-methoxytetrahydrofuran)}, spiro{perhydrocyclopenta[b]furan-2, 2-tetrahydrofuran}, and spiro{2, 3, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-tetrahydrofuran}.For Part XXXI see [1].     

Pyrimidines. 70. Relative reactivities of the chlorine atoms of 2,2′,4-trichloro-4′,5-dipyrimidinyl in its reaction with piperidine

2,2,4-Trichloro-6-phenyl-4,5-dipyrimidinyl, for which nucleophilic substitution with piperdine under various conditions was studied, was obtained from 2,2,4-trioxo-6-phenyl-1, 1,2,2,3,4-hexahydro-4,5-dipyrimidinyl. It is shown that there is an appreciable difference in the rates of substitution of the first, second, and third chlorine atoms, and this made it possible to obtain reaction products that contain one, two, and three piperidino groups. The chlorine atom in the 4 position is replaced initially, after which the chlorine atom in the 2 position undergoes substitution. The structures of the compounds were proved by chemical transformations and analysis of the PMR spectra.See [1] for communication 69.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 821–826, June, 1979.     

Investigations of 2,3′-biquinolyl. 8. Reduction of 1-alkyl-3-(2-quinolyl)-quinolinium halides with sodium borohydride

Reduction of 1-alkyl-3-(2-quinolyl)quinolinium halides with sodium borohydride leads to 1-alkyl-1,2-dihydro-2,3-biquinolyls which, except for the ethoxycarbonyl derivative, undergo rearrangement to 1-alkyl-1,4-dihydro-2,3-biquinolyls. The last can be synthesized by the alkylation of the corresponding 1,4-dihydro-2,3-biquinolyls under conditions of interphase catalysis and in the system KOH-DMSO.For Communication 7, see [1].Stavropol' State University, Stavropol' 355009, Russia; nauka@stavsu.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1084–1087, August, 2000.     

Phase diagram of the system dihexadecylphosphatidylcholine/dihexadecyl-phosphatidic acid/water/NaOH at pH=14

Differential-scanning-calorimetry, freeze-fracture electron microscopy, and³¹P-NMR spectroscopy were used to study the lyotropic and thermotropic properties of the system dihexadecylphosphatidylcholine/dihexadecylphosphatidic acid/water/ NaOH in dispersion with excess water at pH=14. The phase diagram showed that both phospholipids are demixed nearly completely in the gel phase. The coexistence of theP and theB -phase in the mixtures was pointed out in the freeze-fracture electron micrographs by the ripple structure (P -phase) and by the lamellar structure (B -phase).     

Study of the polymer latex coalescence by dielectric measurements at microwave frequency—feasibility of the method

The measurement of the complex dielectric constant ( ^*=–j) in the dipolar absorption domain of the free water molecule (microwave region) permits us to follow quasi-specifically and precisely the water circulation during the coalescence process of a latex. Weight losses and dielectric constants variations have been simultaneously recorded upon latex drying, in a resonant cavity at 5 and 9 GHz and under controlled atmosphere and temperature. Two different latexes were studied (polybutylacrylate (PBuA) and polystyrene (PS)) from which the glass transition temperature effect was investigated. It is found that the harder the polymer particles, the more clearly evidenced the flocculation and packing points are. This method appears to be quite reliable for discriminating the various steps in the film formation process of latexes.     

1,2-Dimethylimidazobenzo-1′, 2′, 3′-thiadiazoles and derived cyanine dyes

New tricylic heterocyclic systems and their methyl derivatives are synthesized. They are 2-methylimidazo[5, 4-e]benzo-1, 2, 3-thiadiazole, 2-methylimidazo[5, 4-g]benzo-1, 2', 3-thiadiazole, 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole, and 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole. Quaternary salts of the 1, 2-dimethyl derivatives are used to prepare symmetrical and unsymmetrical trimethinecyanines and dimethinemerocyanines containing rhodanine groups. The absorption maxima of the dyes are displaced towards the long wavelength region compared with imidacarbocyanines. It is shown that when 1, 2-dimetnyl-5-aminobenzoimidazole is thiocyanated, the thiocyano group enters the benzoimidazole ring at position 4, and that 1, 2-dimethylimidazo[5, 4-e] benzo-1, 2, 3-thiadiazole is less basic than its isomer 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole.     

Comment on the “dielectric properties of LDPE/Ny6 blends”

Data published by La Mantia et al. [1] on dielectric dispersion and loss in polyethylene/nylon 6 blends are analyzed in terms of dielectric mixture formulae. It is shown that an ohmic interfacial polarization process can not be responsible for the unexpected increase of and values observed in these blends at high temperatures. The observed phenomena are tentatively attributed to space charge processes at the electrodes or to other defects dipole mechanisms.     

Synthesis of 2-O-ethyl analogues of 3′-azido- and 3′-fluoro-2′,3′-dideoxyuridines and evaluation of their biological activity against HIV

Summary 2-O-Ethyluracil and 2-O-ethylthymine were silylated with 1,1,1,3,3,3-hexamethyldisilazane and condensed in the presence ofTMS triflate with 2,3-dideoxy-3-fluoro-D-erythro-pentofuranoside, 3-azido-2,3-dideoxy-D-erythro-pentofuranoside, and 2,3-dideoxy-3-phthalimido--D-erythro-pentofuranose derivatives to give the corresponding 2-O-ethyl nucleosides. Deprotection with saturated methanolic ammonia afforded the 2,3-dideoxy-3-fluoro-2-O-ethyluridines, whereas 3-azido-2,3-dideoxy-3-O-ethyluridine was obtained by deprotection with tetrabutylammonium fluoride in tetrahydrofuran. 3-Amino-2,3-dideoxy-3-O-ethyluridine could be obtained only by treatment of the corresponding 3-azido nucleoside with triphenylphosphine in pyridine. 3-Deoxy-2-O-ethyl-3-fluorothymidine (6b) showed moderate activity against HIV-1.

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Synthese von 2-O-Ethyl-Analogen von 3-Azido- und 3-Fluor-23-dideoxyuridinen und Bestimmung ihrer biologischen Aktivität gegenüber HIV

Zusammenfassung 2-O-Ethyluracil und 2-O-Ethylthymin wurden mit 1,1,1,3,3,3-Hexamethyldisilazan silyliert und in Gegenwart vonTMS-triflat mit 2,3-Dideoxy-3-fluoro-D-erythro-pentofuranosid, 3-Azido-2,3-dideoxy-D-erythro-pentofuranosid und 2,3-Dideoxy-3-phthalimido--D-erythro-pentofuranosederivaten zu den entsprechenden 2-O-Ethyl-Nucleosiden umgesetzt. Entfernung der Schutzgruppe mit gesättigter methanolischer Ammoniaklösung lieferte 2,3-Dideoxy-3-fluor-2-O-ethyluridin; 3-Azido-2,3-dideoxy-3-O-ethyl-uridin wurde durch Entschützung mit Tetrabutylammoniumfluorid in Tetrahydrofuran erhalten. 3-Amino-2,3-dideoxy-3-O-ethyl-uridin konnte nur durch Behandeln des entsprechenden 3-Azido-Nucleosids mit Triphenylphosphin in Pyridin hergestellt werden. 3-Deoxy-2-O-ethyl-3-fluor-thymidin (6b) zeigt geringe Aktivität gegenüber HIV-1.

     

Synthesis of some 5′-O-amino acid derivatives of uridine as potential inhibitors ofUDP-glucuronosyltransferase

Summary In an attempt to develop potential inhibitors ofUDP-glucuronosyltransferase, some 5-O-amino acid derivatives of uridine were synthesized. N-protectedL-amino acids were coupled at the 5-O-position of 2,3-O-isopropylideneuridine by esterification employing the method of symmetrical anhydrides in presence of 4-dimethylaminopyridine, 5-O-(N-benzyloxycarbonyl-O-tert.butyl-L-threonl)-23-O-isopropylideneuridine (1), 5-O-(N-tert.butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylideneuridine and (2), 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (3), and 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (4) were obtained in good yield after column chromatography on silica gel. The treatment of2 withTFA/CH₂Cl₂ (6:1) at room temperature for 30 min led to a selective removal of theBoc group without deblocking of the 2,3-O-isopropylidene group of uridine. Treatment of2 withTFA/H₂O (5:1) at room temperature for 1 h, however, released bothBoc and 2,3-isopropylidene groups. TheZ group of1 was deprotected by catalytic hydrogenolysis over 10% Pd/C/ammonium formate.

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Synthese von 5-O-Aminosäurederivaten des Uridins als potentielle Inhibitoren derUDP-Glukuronosyl-Transferase

Zusammenfassung In einem Versuch, potentielle Inhibitoren derUDP-Glukuronosyl-Transferase zu entwickeln, wurden einige 5-O-Aminosäurederivate des Uridins synthetisiert. N-GeschützteL-Aminosäuren wurden durch Veresterung mit der 5-O-Position des 2,3-isopropylidenuridins gekuppelt (Methode der symmetrischen Anhydride in der Gegenwart von 5-Dimethylaminopyridin). Solcherweise wurden 5-O-(N-Benzyloxycarbonyl-O-tert.butyl-L-threonly)-2,3-O-isopropylidenuridin (1), 5-O-(N-tert.Butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylidenuridin (2), 5-O-(N-tert.Butyloxycarbonyl-L-leucyl)-2,3-O-isopropylidenuridin (3) und 5-O-(N-tert.Butyloxycarbonyl-L-valyl)-2,3-O-isopropylidenuridine (4) nach Säulenchromatographie (Kieselgel) in guter Ausbeute hergestellt. Die Behandlung von2 mitTFA/CH₂Cl₂ (6:1) bei Zimmertemperatur (30 min) führte zu einer selektiven Abspaltung derBoc-Gruppe ohne Deblockierung der 2,3-O-Isopropylidengruppe des Uridins. Eine Behandlung von2 mitTFA/H₂O (5:1) bei Zimmertemperatur für 1 Stunde führte hingegen zur Abspaltung sowohl derBoc als auch der 2,3-O-Isopropylidengruppe. DieZ-Gruppe von1 wurde durch katalytische Hydrogenolyse auf 10% Pd/C/Ammoniumformiat abgespalten.