bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of a series of 5-methyl-1H-imidazole-4-ylmethyl sulfides
Authors: Kmoníček Vojtěch , Vejdělek Zdeněk , Protiva Miroslav
Published: February 2010

5-Methyl-1H-imidazole-4-ylmethanethiol (V) hydrochloride was reacted with benzyl chloride, 4-fluorobenzyl bromide, 4-chlorobenzyl chloride, 4-(2-dimethylaminoethoxy)benzyl chloride hydrochloride, 1-chloro-2,3-epoxypropane, 4-fluorophenacyl chloride, 1-bromo-3-phenylpropane, 1-bromo-4-phenylbutane, 1-bromo-5-phenylpentane, 1-bromo-2-methyl-4-phenylbutane, 1-bromo-6-phenylhexane, 1-(benzhydryloxy)-2-bromoethane, 1-bromo-2-(bis(4-fluorophenyl)methoxy)-ethane, 2-(4-chloromethyl)-6,7,8,9-tetrahydro-5H-benzocycloheptene, 2-(4-chlorobutyryl)-6,7,8,9-tetrahydro-5H-benzocycloheptene, and 4-(chloromethyl)-s-hydrindacene in the presence of sodium hydroxide to give the title sulfides VII-XXII, most of which were transformed to salts. Only compounds X and XIII showed some pharmacological activity in tests which are considered predictive of antidepressant action.
Powder ESR spectra of the complexes [Cu(phen)2X]ClO4 and [Cu(bipy)2I]ClO4
Authors: Valko Marián , Mazúr Milan , Pelikán Peter , Kováčik Ivan , Baran Peter , Valigura Dušan
Published: February 2010

The ESR spectra of the polycrystalline [Cu(phen)2X]ClO4 and [Cu(bipy)2I]ClO4 complexes (phen 1,10-phenanthroline, bipy 2,2'-bipyridyl, X = Cl, Br, I) were studied. The values of the optimized parameters of the spin Hamiltonian of the experimental ESR spectra indicate that the CuN4X chromophor has the shape of a compressed trigonal bipyramid with the D3h symmetry, and its structure involves the z2> ground electronic state of the unpaired electron of the Cu(II) ion.
Comparison of copper sulphate pentahydrate growth rates determined by different methods
Authors: Karel Miloslav , Hostomský Jiří , Nývlt Jaroslav , König Axel
Published: February 2010

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.
Kinetically induced multiple steady states during acetylene hydrogenation
Authors: Čapek Pavel , Klusáček Karel
Published: February 2010

An isothermal reaction model of acetylene hydrogenation on palladium catalyst is described. Steady-state solutions of the mass balances in a CSTR display regions of multiplicity caused by the very distinct rate and strength of adsorption and desorption of acetylene and hydrogen, respectively. Uniqueness and local stability of this model are investigated numerically; oscillatory behaviour is predicted to be absent for typical conditions.
Preparation of the zeolite Nu-15
Authors: Dubanská Věra
Published: February 2010

A new vanadium zeolite labelled Nu-15 was prepared. The preparation procedure consists in hydrothermal decomposition of a vanadium glass for 4-10 days at 120-160 °C and saturated vapour pressure in a strongly basic solution of sodium hydroxide. The composition of the starting glasses was 15-17% Na2O, 15-17% Al2O3, 25-40% SiO2 and 30-45% V2O5, the composition of the zeolite, apart from water, corresponds to the formula 2 Na2O.2 Al2O3.6 SiO2.V2O5.
Partial methylation of methyl α-D- and β-D-threofuranoside
Authors: Jarý Jiří , Marek Miroslav , Raich Ivan
Published: February 2010

The methylation rate of hydroxyl groups of the title glycosides I and II has been studied in their reaction with methyl iodide and sodium hydroxide in acetonitrile. From the relative rate constants determined for the side and consecutive reactions taking place the differences in methylation rate of the individual hydroxyl groups have been deduced and are discussed from the standpoint of possible steric and polar effects.
Synthesis of 5-methyl-19-nor-5β-pregn-9-ene derivatives
Authors: Polman Jiří , Kasal Alexander
Published: February 2010

3β,5,6β-Trihydroxy-5α-pregnan-20-one 3-pivalate (I) was converted into 3β,6β-dihydroxy-5-methyl-19-nor-5β-pregn-9-en-20-one 3-pivalate 5-acetate (II) under conditions of Westphalen rearrangement. Deoxygenation in the position 6β was effected by treatment of the corresponding 6β-thiobenzoate or thioimidazolide with tributyltin hydride. Progesterone analogues XII and XIII, prepared from the 6-deoxy compound IX, exhibit abortive activity.
Influence of solvent polarity on the dual fluorescence of p-N,N-dimethylaminobenzonitrile: An AM1 theoretical study
Authors: Ertl Peter
Published: February 2010

Twisting of the NMe2 group in p-N,N-dimethylaminobenzonitrile (DMABN) was investigated using AM1 semiempirical method with configuration interaction. Effect of polar media was considered by placing + and - charge centers ("sparkles") at appropriate places opposite the molecule. Optimized ground state geometry of DMABN is slightly twisted with the lowest vertical excited state of 1B character. As the polarity of media increases and/or the - NMe2 group twists, the symmetric 1A excited state having considerable charge separation becomes energetically favorable. Anomalous long-wavelength emission of DMABN comes from this state.
Effect of steaming on physical properties of aluminium hydroxide and aluminium oxide
Authors: Zun Ro Yong , Polednová Jaroslava , Jirátová Květa
Published: February 2010

The effect of partial pressure of water vapour (50-750kPa) in air on physical properties of calcinated aluminium hydroxide AlOOH and aluminium oxide Al2O3 was examined. For both materials it was found that increasing pressure of water vapour leads to a decrease in the specific surface area and to an increase in the diameter of their mesopores. However, changes in the surface properties have not been identical: the total acidity of Al2O3 decreased whereas the acidity of calcinated AlOOH passed through a maximum. The total basicity of Al2O3 increased while that of AlOOH decreased.
Extraction of polyethylene glycols with dicarbolide solutions in nitrobenzene
Authors: Vaňura Petr , Selucký Pavel
Published: February 2010

The extraction of polyethylene glycol of average molecular mass 400 (PEG 400) with dicarbolide solution in nitrobenzene and of longer-chain polyethylene glycol, of average molecular mass 1 500 (PEG 1 500), with chlorinated dicarbolide solution in nitrobenzene was studied. During the extraction of PEG 400, the polyethylene glycol solvates the Horg+ ion in the organic phase giving rise to the HLorg+ species (L is polyethylene glycol). The obtained value of the extraction constant Kex(HLorg+) = 933 is consistent with published data of metal extraction. Extraction of PEG 1 500 was treated applying the simplified assumption that the thermodynamic behaviour of PEG 1 500 is the same as that of n molecules of polyethylene glycol with relative molecular mass 1 500/n, each solvating one cation. For this model, the value of n = 3.2 ± 1.1 and the values of the extraction constants of the HL1/n,org+ and HL2/n,org+ species were obtained by using the adapted program LETAGROP. This value of n is consistent with published extraction data in the presence of polyethylene glycol with a relative molecular mass from 200 to 1 000.
Optical activity and stereochemistry of (S)-aspartato-dipropylenetriaminecobalt(III) isomers
Authors: Jursík František , Archer Ronald D.
Published: February 2010

The sym-fac-, unsym1-fac-(Λ)-and unsym2-fac-(Δ)-[Co(dpt)(S)-Asp]+ isomers, where dpt is dipropylenetriamine and (S)-Asp is (S)-aspartate, which are formed in the ratio 60:18:22, show very similar circular dichroism spectra due to similar distortions of the triamine nitrogen atoms from the Cartesian coordinates and domination by the vicinal effect from (S)-aspartic acid. Absolute configurations of the unsymmetrical isomers have been tentatively assigned using the calculated configurational contributions of the very low rotatory strenght, which depends on the magnitude of NH2-Co-N(H) triamine bond angles. Distorted chair conformations of one of the two dipropylenetriamine chelate rings provide chirally displaced nitrogen donor atoms which are thought to be responsible for the CD similarity in the isolated isomers. The isomer population is discussed in terms of trigonal bipyramid intermediates with the coordinated oxygen atoms of (S)-Asp preferentially in the trigonal plane and the differences in acidity of α- and β-chain carboxylates.
Polarographic reduction of 1-benzyl-N-(p-X-phenyl)-3-aminocarbonylpyridinium salts
Authors: Krechl Jiří , Beranová Šárka , Volkeová Věra , Volke Jiří , Kuthan Josef
Published: February 2010

The substitution effect of different groups X (N(CH2CH3)2, OH, OCH3, CH3, NHCOCH3, H, Cl, COOCH2CH3 and NO2) on the polarographic behaviour of 3-(N-p-X-phenylaminocarbonyl)pyridines (I), 1-benzyl-N-(p-X-phenyl)-3-aminocarbonylpyridinium cations (II) and their respective 1,4-dihydroderivatives (III) has been investigated in anhydrous solutions of dimethylformamide with 0.1 mol l-1 (n-C4H9)4N+PF6- as supporting electrolyte. The half-wave potentials of the reduction wave of I and II, which correspond to the uptake of a single electron (wave B) and to the formation of a primary radical, obey a Hammett correlation in a similar way as it is in the case of 1-benzyl- and 1-phenyl-3-amino-carbonylpyridinium cations substituted at carbon 4 on the benzene nucleus. The slope ρπ,R in the Hammett plot equals 0.192 V (I) and 0.104 V (II) for anhydrous DMF and compares thus with this slope obtained with the 1-benzyl- and 1-phenyl derivatives in our previous communications.
Proximity and conformation effects in 29Si and 13C NMR spectra of di-ortho substituted trimethylsiloxybenzenes
Authors: Schraml Jan , Brežný Robert , Čermák Jan
Published: February 2010

29Si and 13C NMR spectra of five 4-substituted 2,6-dimethoxytrimethylsiloxybenzenes were studied with the aim to elucidate the nature of the deshielding proximity effects observed in the spectra of ortho substituted trimethylsiloxybenzenes. The sensitivity of 29Si chemical shifts to para substitution is in the studied compounds essentially the same as in mono ortho methoxytrimethylsiloxybenzenes. The deshielding proximity effect of the ìsecondî methoxy group is somewhat smaller than that of the ìfirstî group. The present results indicate that the two methoxy groups assume coplanar conformations with the benzene ring and are turned away from the trimethylsiloxy group which is not in the benzene plane. It is argued that in mono ortho methoxytrimethylsiloxybenzenes the two substituent groups adopt the same conformations as in the compounds studied here.
29Si and 13C NMR spectra of some substituted bis(trimethylsiloxy)benzenes
Authors: Schraml Jan , Brežný Robert , Čermák Jan , Chvalovský Václav
Published: February 2010

NMR spectra of a few 4-substituted 1,2-bis(trimethylsiloxy)benzenes and positional isomers of bis(trimethylsiloxy)benzene were measured under standard conditions that approach those of infinite dilution. Under these conditions somewhat smaller values of steric or proximity deshielding effects on 29Si chemical shifts are found but the trends established earlier are confirmed; the deshielding effect of the ìsecondî ortho positioned trimethylsiloxy group in a tris(trimethylsiloxy)benzene derivative on 29Si chemical shifts is somewhat smaller. Also, overcrowding of three trimethylsiloxy groups probably drives the outer groups to assume, at least for a part of their time, coplanar conformation which is not encountered in bis(trimethylsiloxy) derivatives. The sensitivity of 29Si chemical shifts to para substitution is in 1,2-bis(trimethylsiloxy)benzenes equal to that in 2-methoxytrimethylsiloxybenzenes.
The structure of 1,2,4,4,6-pentamethyl-1,4-dihydropyridine-3,5-dicarbonitrile
Authors: Novotný Jiří , Kurfürst Antonín , Kratochvíl Bohumil
Published: February 2010

The crystal and molecular structure of 1,2,4,4,6-pentamethyl-1,4-dihydropyridine-3,5-dicarbonitrile was solved by direct methods and anisotropically refined by the full-matrix least-squares method to a final R value 0.045 for 1 280 observed reflections (I > 3σ(I)). The compound crystallizes in the Pbca space group with lattice parameters of a = 12.021(1), b = 14.271(2), c = 13.465(1) Å, Z = 8. The six-membered 1,4-dihydropyridine ring of the title compound assumes the boat conformation, while the 1,4-dihydropyridine ring in the related compound, 1-ethyl-2,4,4,6-tetramethyl-1,4-dihydropyridine-3,5-dicarbonitrile, has the envelope conformation. The difference in the fluorescence intensities of these substances can be explained on the basis of this conformational difference. No intermolecular hydrogen bonds were found in the structure, indicating that the crystal is held together by van der Waals interactions.
Some novel heptamethine pyrylium dyes. Structure and photostability
Authors: Luo Weimei , Zhu Zhenghua , Yao Zhuguang , He Mengzhen
Published: February 2010

A series of new heptamethine pyrylium dyes derived from enamine and enaminium salts has been prepared. Spectral absorptions of these dyes range from 850 nm to 1160 nm. Relation between the structure and chromophore has been discussed and kinetic study has been made on the configuration isomerization of the dyes. Photostability has been investigated in relation to the chemical structure.
Synthesis of (19E)-17β-hydroxy-3-oxoandrost-4-en-19-al 19-(O-carboxymethyl)oxime
Authors: Fajkoš Jan , Pouzar Vladimír , Vereš Karel
Published: February 2010

The title compound XIII was synthesized from epoxide I. Cleavage with zinc dust and Jones' oxidation under mild conditions afforded aldehyde V. Reaction with (O-carboxymethyl)hydroxylamine hemihydrochloride followed by methylation with diazomethane led to oxime X which on partial hydrolysis gave the 3-hydroxy derivative VIII. Its oxidation accompanied with a rearrangement of the double bond yielded ketone XVI which on hydrolysis afforded the desired hapten XIII.
DNA-dependent RNA polymerase mediated formation of methylphosphonyl internucleotide linkage
Authors: Horská Květa , Cvekl Aleš , Rosenberg Ivan , Holý Antonín , Šebesta Karel
Published: February 2010

Analogues of ATP modified in the triphosphate moiety by introducing phosphonylmethyl ether residue(s) were used as substrates for bacterial DNA-dependent RNA polymerase. Although the analogues function as poor substrates they enter the initiation as well as the elongation site of the enzyme. The ATP analogue containing the phosphonylmethyl ether group in the α position in the presence of UTP and poly [d(A-T)] gives rise to alternating di- and trinucleotides with one anomalous internucleotide linkage per molecule.
Chemical shifts of charge-transfer complexes and Buckingham equation
Authors: Mohammad Mahboob , Khan Ather Yaseen , Mahmood Tariq , Fatima Ismat , Shaheen Riffat , Iqbal Rashid
Published: February 2010

The 1H NMR spectra of the charge-transfer complex of 1-ethyl-4-methoxycarbonylpyridinium iodide have been recorded in various dipolar aprotic solvents. An attempt is made to interpret the chemical shifts in terms of Buckingham's reaction field equation for spherical cavities. A linear dependence has been found between the δ(2,6) values and the square of dielectric function for a spherical cavity, which confirms the validity of the Buckingham equation for this class of compounds.
Preconcentration of phenmedipham and desmedipham by sorption on Separcol SI C18 T for their determination in drinking water by high performance liquid chromatography
Authors: Tatarkovičová Věra
Published: February 2010

Solvent extraction used routinely for the preconcentration of carbamate herbicides from drinking water was replaced by sorption on the solid sorbent Separcol SI C18 T. Various factors of the preconcentration step that can affect the results of analysis were examined. Real drinking water samples contaminated by phenmedipham were analyzed by RP-HPLC in optimized conditions.
Phenol-sensitive enzyme electrode with substrate cycling for quantification of certain inhibitory aromatic acids and thio compounds
Authors: Macholán Lumír
Published: February 2010

A Clark oxygen electrode coated with a membrane of crosslinked champignon phenol oxidase (tyrosinase)is able to detect phenol containing analytical samples 3-5 times more sensitively after the admixture of hydrazine hydrochloride to the reaction buffer. This compound will recycle the substrate via chemical reduction of the quinoid product thus simultaneously preventing the membrane from rapid blackening. The decrease of oxygen in the membrane due to phenol oxidation is rapidly compensated by diffusion from the bulk solution when an inhibitor of the membrane-bound phenol oxidase is added to the reaction medium. This effect has been utilized for the measurement of low concentrations of compounds decreasing the sensitivity of the bioelectrode either reversibly (benzoic acid, 3- and 4-aminobenzoic acid, salicylic acid, 4-aminosalicylic acid, nicotinic acid, 4-nitrophenol, 1-naphthol) or irreversibly (phenylthiourea, thioacetamide, L-cysteine, reduced glutathione, 2-mercaptoethanol, 2,3-dimercaptopropanol and others). Benzoate as a potent reversible inhibitor markedly stabilizes the phenol oxidase reaction membrane during its storage either in the buffer or in dry state at 4 °C for one year at least.
Distribution of solid particles in a mixed vessel
Authors: Bílek Petr , Rieger František
Published: February 2010

The aim of our research was to study the axial, radial and tangential solid phase concentration profiles in a mixed vessel. The conductivity method was used for the concentration measurement. We accomplished the measurement in eleven points in five heights above the vessel bottom. The points were situated on three vertical planes passing through the vessel axis and on five values of radii. It was determined by means of statistic test of variance if it was possible to measure the concentration only in one point in each distance from the vessel bottom and neglect the radial and tangential concentration differences.
Microenvironment of polymer chains in solution: pKa of indicators bound to the polymer chain
Authors: Mikeš František , Labský Jiří , Výprachtický Drahomír , Chalabala Jiří
Published: February 2010

Polymers bearing at the end of side chains acidobasic indicator moieties exhibiting a solvatochromic absorption band were prepared by a polymeranalogous reaction of copolymers N-(2-hydroxy propyl) methacrylamide-N-methacryloylated 4-nitrophenyl ester ω-aminoacids with 1-(2-aminoethyl)-4-(4-hydroxystyryl)pyridinium bromide. It was found that pKa of reporters bound at a medium long side chain (six methylene groups) is close to pKa of a low-molecular model compound, while pKa of a reporter bound close to the polymer backbone is approximately by one pKa unit higher. Changes in the pKa value of the reporters are discussed in connection with a change in the polarity of microenvironment of polymer chains.
On particle size distribution in suspension polymerization of styrene
Authors: Apostolidou Christina , Stamatoudis Michael
Published: February 2010

Experiments were conducted on some of factors affecting the polymerized particle size distribution in suspension polymerization of styrene. Polymerization experiments with styrene at 80 °C showed that the final polystyrene product size distribution is strongly affected by the stabilizer concentration, the type and the speed of impeller, and the hold-up fraction.
A convenient synthesis of 2,13- and 3,13-octadecadienyl acetates, sex pheromone components of the Synanthedon species
Authors: Hoskovec Michal , Šaman David , Koutek Bohumír
Published: February 2010

The sex pheromone components of several Synanthedon species, 2,13- and 3,13-octadecadienyl acetates (Ic, Id, IIc, IId), have been synthesized following the acetylenic route of chain elongation. Starting from ω-alkyn-1-ols III, the final compounds were constructed in five steps in about 30% overall yields. Transformation of triple bond containing intermediates into the corresponding (Z)- and (E)-olefins was achieved either by hydrogenation over the P2-Ni catalyst or by using a dispersion of sodium in toluene. The title pheromones were generated in more than 97% stereoisomeric purity. 1H and 13C NMR data of all derivatives are included.
Tricyclic neuroleptics: Synthesis of metabolites of isofloxythepin and some related compounds
Authors: Šindelář Karel , Jílek Jiří , Pomykáček Josef , Valenta Vladimír , Hrubantová Marta , Vlková Marie , Holubek Jiří , Svátek Emil , Ryska Miroslav , Metyšová Jiřina , Protiva Miroslav
Published: February 2010

The isofloxythepin (I) metabolite IV was synthesized via the acids IX and XI and the esters X and XII. The enamine VIII was prepared from 3-fluoro-8-(2-propyl)dibenzo[b,f]thiepin-10(11H)-one by two methods and was reduced to I. Cloflumide (II) was obtained by reaction of 2,10-dichloro-7-fluoro-10,11-dihydrodibenzo[b,f]thiepin with 3-(1-piperazinyl)propionamide and was oxidized to the sulfoxide XVI. The unsaturated analogue XVII of clopithepin (III) was prepared from 2-chlorodibenzo[b,f]thiepin-10(11H)-one by reaction with 2-bromoethanol in the presence of 4-toluenesulfonic acid in boiling benzene and by the following substitution reaction with 2-(1-piperazinyl)ethanol. An improved synthesis of 6-methyldibenzo[b,f]thiepin-10(11H)-one (XIX) was elaborated. The acid XXVII was synthesized and cyclized with polyphosphate ester. A mixture of compounds was formed from which the ketone XXXVI was isolated and processed by reaction with formamide and formic acid at 200 °C. One of the products was characterized as the formamide XXXIII and was reduced with lithium aluminium hydride to a basic product supposed to be XXXIV. A series of by-products was isolated and characterized. The enamine VIII (V⁄FB-17 156) was found to be a strong neuroleptic agent, similar to isofloxythepin (I). The enol ether XVII (V⁄FB-17 733) was characterized as a mild, practically noncataleptic neuroleptic agent.
Potential cholinergic and anticholinergic compounds: Synthesis of 2,8-substituted 2,8-diazaspiro[4,5]decane-1,3-diones
Authors: Valenta Vladimír , Holubek Jiří , Svátek Emil , Protiva Miroslav
Published: February 2010

Heating the ammonium salt of (4-carboxy-1-methyl-4-piperidinyl)acetic acid (XII) gave 8-methyl-2,8-diazaspiro[4,5]decane-1,3-dione (II) which was N-alkylated with 2-bromoethanol and 4-bromobutanol to give the alcohols III and V. Compound III was transformed to the chloro compound VI which was reacted with the sodium salt of hexahydrobenzilic acid to give the ester VII. Compound V was transformed to the 4-toluenesulfonic ester VIII which reacted with 1-(2-pyrimidinyl)piperazine and gave IX. 2-(2-Propyl)-2,8-diazaspiro[4,5]decane-1,3-dione (XVIII) was similarly transformed via XIX to XX which reacted with the sodium salts of diphenylacetic, benzilic, hexahydrobenzilic, and (2-oxo-1-pyrrolidinyl)acetic acid to give the esters XXI-XXIV. The esters VII and XXI-XXIV were transformed to the methiodides. The compounds prepared were tested in the lines of activity of the analogous "RS-86" (I) but proved inactive.
The interactions of opioids with enterocyte membranes: Evidence for enzyme-catalysed covalent binding
Authors: Yarigin Konstantin N.
Published: February 2010

The binding of the synthetic opioid hexapeptide Tyr-D-Ala-Gly-Phe-Leu-Arg (dalargin) to rat enterocyte membranes has been studied and compared to its interaction with central opioid receptors. The binding was apparently low affinity, time- and temperature-dependent, sensitive to NaF and N-ethylmaleimide, and esentially irreversible even after incubation with trichloracetic acid. It was inhibited by ascorbate and substances containing hydroxybenzol moieties or halogenósubstituted aromatic rings. The binding of [14C]phenol and [3H]tyrosine to rat enterocyte membranes was very similar to the binding of dalargin. The interaction of dalargin with rat enterocyte membranes differed in many ways from its binding to opioid receptors, but it was similar to the covalent binding of hydroxybenzol derivatives to proteins catalyzed by cytochrome P-450 enzyme complex.
Synthesis of some derivatives of 1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine and 11-phenyl-5,6-dihydro-11H-s-triazolo[3,4-b]-3-benzazepine
Authors: Vejdělek Zdeněk , Protiva Miroslav
Published: February 2010

Article without abstract
The structure of (1-2:5-6-η-cycloocta-1,5-diene)-(η5-cyclopentadienyl)cobalt(I)
Authors: Ondráček Jan , Schehlmann Volker , Maixner Jaroslav , Kratochvíl Bohumil
Published: February 2010

The structure of the title complex, C13H17Co(232.2), was determined by the heavy-atom method and anisotropically refined to the value R = 0.029 for 1 558 observed reflections (I > 1.96σ(I)). The substance crystallizes in the monoclinic space group P21/c; a = 12.6744(6), b = 7.3887(5), c = 11.4519(8) Å, β = 102.91(1)°, Z = 4. The molecule has the sandwich-arrangement, in which cycloocta-1,5-diene ring assumes the boat conformation. The bond distances to the Co atom, in the range of 2.010-2.025 Å, are short. The relatively strong interactions of the π-orbitals of the diolefin with the cyclopentadienyl-Co fragment is manifested in the elongation of the C=C bonds (1.411 and 1.412 Å).
The reaction of Cl3P=N-P(O)Cl2 with mercaptans
Authors: Mareček Aleš
Published: February 2010

In reactions of Cl3P=N-P(O)Cl2 with mercaptans in the presence of pyridine as a hydrogen chloride acceptor, the compounds (RS)3P=N-P(O)Cl2 (R = C2H5-, C3H7-, C8H17-) were found to be the final products. The hitherto unknown (RS)2ClP=N-P(O)Cl2was also identified in the reaction mixture by 31P NMR spectroscopy.
CO2 laser induced decomposition of propylene oxide
Authors: Jakoubková Marie , Pola Josef
Published: February 2010

The continuous-wave (cw) CO2 laser induced decomposition of propylene oxide yields propanal, propanone and methyl vinyl ether as primary isomerization products. The absence of allylol and great amounts of ethene among products of ensuing fragmentation of primary products make the reaction different from conventional thermal decomposition of propylene oxide. CW CO2 laser induced decomposition of methyl vinyl ether affords propanal as isomerization product and shows thermal interconvertibility of propylene oxide and methyl vinyl ether.
Synthesis and cyclization kinetics and mechanism of 1-(2-ethoxycarbonylphenyl)-3-aryltriazenes. Kinetic acidity function of sodium methoxide in methanol
Authors: Pytela Oldřich , Dlouhý Vladimír
Published: February 2010

Eight 1-(2-ethoxycarbonylphenyl)-3-aryltriazenes have been synthetized and the rate constants of their sodium-methoxide-catalyzed cyclization have been measured in methanol at 25 °C. The experimental rate constants kobs have been adopted to construct the kinetic acidity function HKM which has been shown to be identical with the -log[CH3O-] values. Two mathematical procedures have been used to determine the catalytic rate constants and their dependence on the Hammett substituent constants. A closer dependence is obtained with the σ values than with the σp- values. The ρ value found (0.3) indicates a compensation of the substituent effects upon the dissociation of the starting triazene and upon the subsequent reaction of the conjugated base. Out of the two mechanistic alternatives - E1cB and BAc2 - the latter appears to be more probable, the splitting of tetrahedral intermediate being its limiting step.
Cycloadditions of 2,5-dimethyl-3-furannitrile oxide to alkenes and alkynes
Authors: Jedlovská Eva , Fišera Lubor , Balková Anna , Kováč Jaroslav , Štibrányi Ladislav
Published: February 2010

Regioselectivity of 1,3-dipolar cycloadditions of 2,5-dimethyl-3-furannitrile oxide (IIa) to alkenes or alkynes is described. Nitrile oxide IIa generated in situ reacts with monosubstituted alkenes or alkynes to give exclusively 5-substituted 3-(5-dimethyl-3

-furyl)-2-isoxazolines IV and isoxazoles V, 2,5-disubstituted alkenes sometimes afforded a mixture of regioisomeric isoxazolines. Reactivity of furannitrile oxides II and III in cycloadditions to ethene was studied by the MNDO method.
An unusual tert-butylamine mediated conversion of 6-aryl-7-formyl-2,4,5,8-tetrahydro-1,3-dioxa-5-azocines to 1,2,3,6-tetrahydropyrimidine derivatives
Authors: Štibrányi Ladislav , Fišera Lubor , Káčer Rastislav , Oremus Vladimír , Mihulová Martina
Published: February 2010

An unexpected contraction of the 8-membered ring to a 6-membered one occurring when 6-aryl-7-formyl-2,4,5,8-tetrahydro-1,3-dioxa-5-azocines II were treated with tert-butylamine afforded 4-aryl-5-formyl-1-(1,1-dimethylethyl)-1,2,3,6-tetrahydropyrimidines III. Reaction conditions for the photorearrangement of chlorophenyl-substituted condensed isoxazolines I to II were worked out. The reaction sequence: 1,3-dipolar cycloaddition, photochemical rearrangement, treatment with tert-butylamine constitutes a new route to pyrimidine derivatives from 2H,4H,7H-1,3-dioxepine.
Modification of MSH release-inhibiting hormone
Authors: Mazurov Anatolii A. , Andronati Sergei A. , Kabanov Vladimír M. , Sokolenko Nikolai I. , Rokachinskaya Margarita G. , Shapiro Yurii E. , Gorbatyuk Vitalii Ya.
Published: February 2010

[Phe2]MIF (I) and the ring substituted analogues (II-V) have been synthesized. Their antidepressant activity was estimated by Porsolt's test.
Chemical equilibria including particles I-, I3-, I5-, and I2 in two-phase water-nitrobenzene extraction system
Authors: Makrlík Emanuel
Published: February 2010

General relations among thermodynamic parameters characterizing chemical equilibria with species I-, I3-, I5-, and I2 in the two-phase water-nitrobenzene extraction system have been derived. Furthermore, these relations have been used for calculating equilibrium constants K1aq(I3-) and K2aq(I5-) corresponding to homogeneous reactions I-(aq) + I2(aq) ⇄ I3-(aq) and I3-(aq) + I2(aq) ⇄ I5-(aq) proceeding in the aqueous phase of the system under study. Finally, stability of polyiodides I3- and I5- in both phases has been discussed.
Contribution to the thermodynamics of bromophenol blue in the two-phase water-nitrobenzene extraction system
Authors: Makrlík Emanuel
Published: February 2010

General relations among thermodynamic parameters characterizing dissociation equilibria with species H2A, HA- and A2- (H2A is a symbol for an electroneutral undissociated acid) in a two-phase extraction system have been derived. From the extraction measurements, the equilibrium distribution constant of electroneutral bromophenol blue between the nitrobenzene phase and the aqueous one has been determined: log KD(H2A) = 3.60 ± 0.01. By using this value and further known constants and applying the mentioned relations the following values of dissociation constants of bromophenol blue in nitrobenzene saturated with water have been calculated for a temperature of 25 °C: pKaorg(H2A) = -log Kaorg(H2A) = 10.1 and pKaorg(HA-) = -log Kaorg(HA-) = 14.5.
Study of the influence of tetraalkylammonium salts on the dissolution of aluminium in aqueous NaOH solutions
Authors: Miadoková Milica , Halaša Ivan , Koreň Martin
Published: February 2010

Tetraalkylammonium halides decelerate the reaction of aluminium in aqueous NaOH solutions. Their effect depends on the alkyl group, on the anion, and on their concentration; and it is additive with the effect of Ca2+ ions. The inhibition effects under study and the shift of the stationary potentials to more anodic values are shown to be related with the influence on the cathodic process, resulting in a retardation of the whole corrosion process.
Synthesis, kinetics and mechanism of cyclization of 1-(2-aryloxycarbonylphenyl)-3-phenyltriazenes
Authors: Pytela Oldřich , Bahník Zdeněk
Published: February 2010

Twelve substituted 1-(2-aryloxycarbonylphenyl)-3-phenyltriazenes have been synthetized and kinetics of their reactions have been measured in 52.1% (by mass) aqueous methanol at pH 3 to 11. Plots of kobs vs pH show three regions: noncatalyzed cyclization (pH 4 to 7), acid-catalyzed splitting of the triazene chain, and base-catalyzed cyclization. The non-catalyzed cyclization exhibits a kinetic isotope effect, the reaction constant ρ = 2.69 (σ-p), and β1g = 1.02, which indicates a mechanism of E1cB type with intramolecular proton transfer and a transient formation of a ketene intermediate. The base-catalyzed cyclization, on the other hand, exhibits the reaction constant ρ = 1.05 (σ-p), β1g = 0.4, and distinct steric effects, which indicates a cyclization by BAc2 mechanism with rate-limiting formation of the tetrahedral intermediate.
4-(5-Phenyl-1,3,4-oxadiazol-2-yl)biphenyl-4'-carboxylic acid: Its functional derivatives and their heterocyclization into 1,3-thiazine-6-thiones
Authors: Kurfürst Antonín , Kuthan Josef , Lhoták Pavel , Nádeník Petr , Schroth Werner , Spitzner Roland
Published: February 2010

The title carboxylic acid II prepared by hypobromide oxidation of 4'-acetyl derivative I was converted into its functional derivatives III-IX by standard preparative procedures. The C-acylation of 1,1-dichloroethene with acyl chloride III gave dichloroethenyl ketone X affording 2,4-disubstituted 1,3-thiazine-6-thiones XIa-XIe and XII by cyclocondensations with appropriate thioamides. The reactivity of heterocycles XIb, XIc was checked by their conversion into the expected products XIII-XV. IR and NMR spectroscopic patterns of the new prepared compounds are discussed.
Synthesis and conformation of some 6-aminomethyluracil amides
Authors: Stibor Ivan , Šaman David , Fiedler Pavel
Published: February 2010

Three model amides (I-III) derived from 6-(N-alkylaminomethyl)-uracil and arylcarboxylic acids were synthesized and their conformation in solution studied. The 7-membered intramolecular hydrogen bond between amide carbonyl and H-N1 of uracil nucleus was proved to exist in solution of all three compounds using NMR and IR spectroscopy.
A route to 24-epibrassinolide from ergosterol avoiding the use of osmium tetroxide
Authors: Černý Václav , Buděšínský Miloš
Published: February 2010

A synthesis of (22R,23R)-2α,3α,22,23-tetrahydroxy-5α-ergostan-6-one (V) from the dienone IV via the diepoxide XXII is described. The tetrol V is a key intermediate in the synthesis of 24-epibrassinolide. The reactivity of the side chain was studied on 5α-ergost-22-en-6-one (XIV) as a model compound. 1H and 13C NMR spectra of 24-epibrassinolide derivatives are discussed.
Cibacron Blue inhibition of prokaryotic and eukaryotic DNA-dependent RNA polymerases
Authors: Cvekl Aleš , Horská Květa
Published: February 2010

A comparison was drawn between the action of Cibacron Blue F3GA on the enzymic activity of DNA-dependent RNA polymerases from different sources, e.g. Escherichia coli, calf thymus and wheat germ (polymerase II). Sensitivity towards this inhibitor was determined for polymer formation and primed abortive synthesis of trinucleotide UpApU. In case of E. coli polymerase and wheat germ polymerase II the dye inhibits both polymer formation and abortive synthesis. Calf thymus polymerase II is inhibited only in the polymerisation step. The primed initiation reaction was found to be resistant towards the dye. In case of E. coli polymerase and wheat germ polymerase II the sensitive step is the formation of internucleotide bond whereas in case of calf thymus polymerase II the translocation of the enzyme is influenced. An analysis of kinetic data indicates more than one binding site for the dye on RNA polymerase II from calf thymus and wheat germ. Cibacron blue does not inhibit specific transcription catalyzed by RNA polymerase III from human HeLa cells and mouse leukemia L1210 cells.
Preparation of naphtho[2,1-e]pyrazolo[5,1-c][1,2,4]triazine, dipyrazolo[5,1-c:3',4'-e][1,2,4]triazines and pyrazolo[5,1-c][1,2,4]triazine derivatives
Authors: Deeb Ali , El-Mobayed Medhat , Essawy Abd El-Naby , El-Hamid Adel Abd , El-Hamid Atef Abd
Published: February 2010

Article without abstract
Quaternary benzo[c]phenanthridine alkaloids
Authors: Dostál Jiří , Potáček Milan
Published: February 2010

This review deals with the fully aromatic quaternary benzo[c]phenanthridine alkaloids in several aspects. Firstly nomenclature principles for numbering fused heterocycles are given. Then the richest botanical sources of quaternary benzo[c]phenanthridines are mentioned as well as isolation, separation and determination methods are presented. The emphasis of this survey is focused on chemical reactivity. The main pharmacological effects of quaternary benzo[c]phenanthridine alkaloids are discussed.
Reactivity of substituted styrenes in the catalytic addition reaction with the trichloromethyl radical
Authors: Hájek Milan , Šilhavý Přemysl , Špirková Božena
Published: February 2010

Relative reactivities have been investigated in the catalytic addition of tetrachloromethane to substituted styrenes by the competitive method. The polar effects of substituents on benzene ring were correlated with Hammett equation for a copper and ruthenium catalyst, giving ρ values equal to -0.39 and -0.18 respectively. The results indicate that in contrast to classical additions the catalytic addition of tetrachloromethane is not a free radical chain process but that the trichloromethyl radical, presumably coordinated, reacts with the carbon-carbon double bond via innersphere pathways.
The analogs of 8-D-homoarginine-vasopressin with p-substituted phenylalanine in position 2; Synthesis and some biological properties
Authors: Žertová Miroslava , Procházka Zdenko , Bláha Ivo , Barth Tomislav , Slaninová Jiřina , Maletínská Lenka , Lebl Michal
Published: February 2010

Solid phase methodology on benzhydrylamine resin was used for the synthesis of five analogs of vasopressin with non-coded amino acid, D-homoarginine, in position 8 and p-substituted D or L phenylalanine in position 2. Besides the mother analog, [D-Har8]vasopressin (I), [L-Phe(Me)2, D-Har8]vasopressin (II), [D-Phe(Me)2, D-Har8]vasopressin (III), [L-Phe(Et)2, D-Har8]vasopressin (IV), [D-Phe(Et)2, D-Har8]vasopressin (V) were synthesized. All analogs have very low antidiuretic and pressor activities. Analogs containing p-ethylphenylalanine of both D and L configuration are pressor inhibitors. All analogs substituted in position 2 were found to be uterotonic inhibitors, the most potent being [D-Phe(Et)2, D-Har8]vasopressin (V) with pA2 8.15.
An efficient esterification of pullulan using carboxylic acid anhydrides activated with iodine
Authors: Hussain Muhammad A. , Shahwar Dure , Hassan Muhammad N. , Tahir Muhammad N. , Iqbal Mohammad S. , Sher Muhammad
Published: February 2010

Acylation of alcohols (esterification) with anhydride is an important and routinely utilized transformation in organic synthesis. Iodine is a cheap and one of the most powerful anhydride activating agents for the esterification of alcohols. Therefore, an efficient and cost effective method was developed for the acylation of pullulan polysaccharide by using different acid anhydrides activated with iodine. A series of organo-soluble pullulan esters were successfully synthesized, purified and characterized. Under solvent free conditions, it was feasible to fabricate pullulan nonaacetate and pullulan stearate. Attachment (covalent) of the pendant groups onto polymer backbone was verified by spectroscopic techniques. All of the products were characterized by using thermal analysis, FTIR and 1H NMR spectroscopy.
Silicified trilobites of the genusSphaerocoryphefrom the Middle Ordovician of Virginia
Authors: Tripp Ronald P. , Rudkin David M. , Evitt William R.
Published: February 2010

Two similar species of Sphaerocoryphe, Sphaerocoryphe gemina sp.nov. and Sphaerocoryphe longispina sp.nov., from the Edinburg Formation (Blackriveran) of northwest Virginia are described. The most conspicuous differences lie in the pygidia. The protaspis closely resembles that of Ceraurinella; transitory pygidia are allocated to degrees one to eight, and the first appearance of the great spines provides a useful marker. Two ontogenetic series can be recognized, culminating in the two adult morphologies, and ruling out the possibility of a single dimorphic species. There are two profixigenal spines in meraspid cranidia up to 2.5 mm in sagittal length, one pair in larger cranidia of both species. The smallest hypostome possesses two lateral spines, later reduced to one. Hemisphaerocoryphe Reed is considered a junior subjective synonym of Sphaerocoryphe Angelin. The 29 named species are compared.
Compositional and thermal state of the upper mantle beneath the Bering Sea basalt province: evidence from the Chukchi Peninsula of Russia
Authors: Akinin Vyacheslav V. , Apt Julia , Roden Michael F. , Francis Don , Moll-Stalcup Elizabeth
Published: February 2010

Nephelinites and basanites of the Enmelen volcanic field, Chukchi Peninsula, Russia, contain upper mantle xenoliths of relatively calcium- and magnesium-rich spinel lherzolites, pyroxenites, and megacrysts. The phase assemblages of the lherzolites require equilibration near 1.5 GPa, and calculated equilibration temperatures for most inclusions are in the range 850–1030 °C. These temperatures are similar to those calculated for lherzolite inclusions from other Bering Sea localities (Nunivak Island and Seward Peninsula) and are higher than temperatures expected for likely conductive geotherms beneath these volcanic fields. The relatively high temperatures may be the result of magma intrusion into the mantle lithosphere and consequent perturbation of the geotherm shortly before entrainment of the xenoliths in basalt. Two Enmelen lherzolites equilibrated at higher temperatures (1230–1240 °C) and provide further evidence for heating due to intrusive magmas. Some spinel lherzolite inclusions have flat rare earth element patterns and major and trace element abundances close to that of the bulk silicate earth. Based on the occurrence of similar fertile peridotites at Nunivak Island and Seward Peninsula, near-primitive mantle compositions appear to be common in the upper mantle beneath the Bering Sea. These peridotites may represent recent additions to the mantle lithosphere from mantle plumes related to the volcanism. Other Enmelen inclusions are relatively light rare earth element-enriched group I lherzolites metasomatized by a silicate melt, group II pyroxenites precipitated from a variety of melts, and augite megacrysts with convex-upward rare earth element patterns consistent with precipitation from the host basalts at high pressures.
Alleghanian reactivation of the Acadian fold belt, Meguma Zone, southwest Nova Scotia
Authors: Culshaw Nicholas , Liesa Montserrat
Published: February 2010

Shear zones and northwest-verging folds define a 30 km wide belt of deformation that overprints the Acadian fold belt and telescopes isograds in the Meguma Zone in southwest Nova Scotia. The shear zones appear to form a linked system that accommodated convergence-dominated transpression of the Meguma Zone against an irregular Avalon boundary. Available geochronological data indicate a Mid-Carboniferous (Alleghanian–Variscan) age for the overprinting deformation. The Mid-Carboniferous basement reactivation in southwest Nova Scotia is likely coeval with deformation of Carboniferous strata and reactivation of basement structures (Meguma Group) in the northern Meguma Zone. Together, these Mid-Carboniferous structures may define a wide belt of Alleghanian–Variscan deformation across the northwest (cratonward) margin of the Meguma Zone.
Nina Creek Group and Lay Range Assemblage, north-central British Columbia: remnants of late Paleozoic oceanic and arc terranes
Authors: Ferri Filippo
Published: February 2010

In north-central British Columbia, a belt of upper Paleozoic volcanic and sedimentary rocks lies between Mesozoic arc rocks of Quesnellia and Ancestral North America. These rocks belong to two distinct terranes: the Nina Creek Group of the Slide Mountain terrane and the Lay Range Assemblage of the Quesnel terrane. The Nina Creek Group is composed of Mississippian to Late Permian argillite, chert, and mid-ocean-ridge tholeiitic basalt, formed in an ocean-floor setting. The sedimentary and volcanic rocks, the Mount Howell and Pillow Ridge successions, respectively, form discrete, generally coeval sequences interpreted as facies equivalents that have been interleaved by thrusting. The entire assemblage has been faulted against the Cassiar terrane of the North American miogeocline. West of the Nina Creek Group is the Lay Range Assemblage, correlated with the Harper Ranch subterrane of Quesnellia. It includes a lower division of Mississippian to Early Pennsylvanian sedimentary and volcanic rocks, some with continental affinity, and an upper division of Permian island-arc, basaltic tuffs and lavas containing detrital quartz and zircons of Proterozoic age. Tuffaceous horizons in the Nina Creek Group imply stratigraphic links to a volcanic-arc terrane, which is inferred to be the Lay Range Assemblage. Similarly, gritty horizons in the lower part of the Nina Creek Group suggest links to the paleocontinental margin to the east. It is assumed that the Lay Range Assemblage accumulated on a piece of continental crust that rifted away from ancestral North America in the Late Devonian to Early Mississippian by the westward migration of a west-facing arc. The back-arc extension produced the Slide Mountain marginal basin in which the Nina Creek Group was deposited. Arc volcanism in the Lay Range Assemblage and other members of the Harper Ranch subterrane was episodic rather than continuous, as was ocean-floor volcanism in the marginal basin. The basin probably grew to a width of hundreds rather than thousands of kilometres.
Dehydration and decomposition of pyrophyllite at high pressures: electrical conductivity and X-ray diffraction studies to 5 GPa
Authors: Hicks Tara L. , Secco Richard A.
Published: February 2010

The dehydration and decomposition of South African pyrophyllite were studied in the pressure range 2.5–5.0 GPa and in the temperature (T) range 295–1473 K using both in situ electrical conductivity measurements and X-ray diffraction studies on the recovered samples. Activation energies for conduction (Qc) vary in the range 0.02–0.07 eV for T ≤ 500 K where the dominant conduction mode is electronic, and Qc is in the range 1.10–1.28 eV for T ≥ 500 K where ionic conduction dominates. Abrupt changes in the isobaric temperature dependence of conductivity mark the onset of dehydration and subsequent decomposition into kyanite plus quartz–coesite. At 2.5 GPa, South African pyrophyllite forms the dehydroxylate phase at 760 K with a pressure dependence of ~30 K/GPa and complete decomposition follows at 1080 K with a pressure dependence of ~41 K/GPa. The resulting pressure–temperature phase diagram is in very good agreement with many previous studies at 1 atm (101.325 kPa).