bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioimmunoassay of angiotensin i in human plasma ‐ comparison of two renin activity methods
Authors: Lijnen P. J. , Amery A. K. , Fagard R. H. , Fyhrquist F. 
Published: September 2010

AbstractPlasma renin activity (PRA) was measured by radioimmunoassay of angiotensin I generated during 1 hour incubation at the pH‐optimum. Angiotensin I was then assayed directly in the plasma or after extraction on a Dowex resin. A significant (p < 0.001) correlation between the PRA‐values obtained with both methods was observed. PRA determined in untreated (r = 0.79, p < 0.001) or extracted (r = 0.87, p < 0.001) plasma samples, was similarly related to simultaneously measured plasma angiotensin II levels. The predictive value of PRA, determined with both methods, in the hypotensive action of saralasin (an angiotensin II antagonist) and of captopril (an orally active angiotensin converting enzyme inhibitor) was of the same magnitude.
Benzo [b] tellurophènes substitues en position 3
Authors: Talbot J‐M. , Piette J‐L. , Renson M. 
Published: September 2010

Abstract3‐substituted benzo (b) tellurophenes can be obtained through Wittig or Wittig‐Horner reaction on 2 H‐benzo (b) tellurophene‐3‐one (telluroindoxyl). This reaction shows a partial isomerisation specific of the tellurium series, due to breaking of Te‐CH2 bond. The products so obtained can lead to various mono 3‐substituted derivatives (CH3, CHO, CH2OH, COOH, COOCH3, CN, CONH2).Reaction of triphenylphosphin/TeX4 on the same substrate leads to 3‐chloro and 3‐bromo benzo (b) tellurophenes, which could not be obtained by halogenation of the basic heterocycle. Acetylation of benzo (b) tellurophene with Ac2O/CF3COOH leads to a mixture 76/24 of 2‐acetyl and 3‐acetylbenzo (b) tellurophenes, which could be separated through thin‐layer chromatography.
Thermal Decomposition Studies: Part II kinetics of dehydration of transition metal complexes of salicylic acid
Authors: Heda B. D. , Khadikar P. V. , Gogne O. K. 
Published: September 2010

AbstractVarious kinetic parameters of the thermal dehydration reaction of metal complexes of salicylic acid with Fe (II), Zn (II), and VO (II) have been evaluated using Horowitz and Metzger and Fuoss methods. Observed kinetic parameters indicate the first order reaction. The activation energy of the thermal dehydration decreases in the order ‐ VO > Zn > Fe.
Zerovalent metal phosphite complexes. Synthesis of RE2 [P (OCH3)3]10
Authors: Choi Henry W. , Muetterties E. L. 
Published: September 2010

AbstractReaction of rhenium pentachloride and pyridine with potassium ‐ potassium iodide followed by a heating of the nonvolatile reduction residue with trimethyl phosphite gave Re2 [P(OCH3)3]10. A minor co‐product was HRe [P (OCH3)3]5 which presumably was generated from a radical intermediate like Re [P (OCH3)3]4 or 5 by a hydrogen atom abstraction from the organic reagents. Both Re2 [P(OCH3)3]10 and HRe [P(COH3)3]5 exhibited a nearly first order AB4 31P{1H} NMR spectrum. Neither complex showed the extreme photosensitivity (photodissociation of phosphite ligand) shown by W [P(OCH3)3]6 but the dimer was easily converted to the hydride by reaction with hydrogen.
Substitution at saturated carbon. Part 25. The iododemetallation of benzyltrialkyltins in methanol
Authors: Abraham Michael H. , Andonian‐Haftvan Jenik 
Published: September 2010

AbstractThe action of I2/I1 in methanol on compounds PhCH2SnR3 leads only to cleavage of the benzyl group (as PHCH2I) when R=Et, Prn or Bun. With PhCH2SnMe3, both benzyl and methyl groups are removed. Rate constants are reported for the iododemetallation of all four PhCH2SnR3 compounds, R=Me, Et, Prn and Bun. The present results and previous literature data show that with a constant SnR31 leaving group, the sequence of alkyl‐tin reactivity is Ph>PhCH2>Me>Et>Prn, with the benzyl‐tin bond being broken 3–4 times as rapidly as the methyl‐tin bond and about 40 times as rapidly as the ethyl‐tin bond. The effect of added anions, C𝓁, Br−, I− and C𝓁O4− on the rate constants (and products) are reported, and it is shown that both kinetic studies and product analyses lead to the conclusion that foreign anions do not participate in the reaction mechanism. These are, however, specific kinetic salt effects in the order NaBr<NaC𝓁<NaC𝓁O4<NaI.
NQR study of tetrametric ET3 YCU(I)X (Y = P, AS; X = CI, BR, I) COMPLEXES
Authors: Valigura D. , Verdonck L. , van Der Kelen G. P. 
Published: September 2010

AbstractThe geometry and electronic distribution of the tetrametric (Et3YCu(I)X)4 (Y = P, As; X = CI, Br, I) complexes can be rationalized within the “bonded” interaction scheme (electronegativity effect) as well as in the non‐bonded (steric effect). Both effects operate in the same direction explaining the socalled softness of the cubane frame.The anomalous behaviour of the 63Cu NQR frequencies is caused by small specific bonded and nonbonded interactions affecting specially the electric field gradient and the field gradient asymmetry parameter.
Synthèse directe et propriétés biocides de benzyletains substitues
Authors: Mahieu B. , Hubesch B. , Maraite H. 
Published: September 2010

AbstractDirect synthesis is the most economic way to produce organometallic compounds. In tin chemistry, it is well known that benzyl chloride gives very easily benzyltin derivatives. However, these latter show poor performances regarding to the phenyl or alkyltin compounds.In this work, some ring‐substituted benzyl chlorides were used as reagent and the antifungal activity of the obtained tribenzyltins was measured.It is found that substitution exerts an unfavourable effect on the biological properties of the products.
Electron, Transfer from Metal Surfaces. Formation of Lithium and Grignard Reagents1
Authors: Walborsky H. M. , Banks R. Bruce 
Published: September 2010

AbstractChiral (+)‐(S)‐4‐methylcyclohexylidenebromomethane (1) has been prepared from (−)‐(R)‐4‐methylcyclohexylideneacetic acid by a stereospecific bromode‐carboxylation reaction. The reaction was shown to proceed with an overall inversion of configuration.The reaction of the chiral vinyl bromide with lithium and magnesium metal surfaces produced the corresponding chiral vinyllithium and Grignard reagents. The mechanism of formation of these reagents will be discussed.
Mass spectrometry of organometallic compounds I. the fragmentation upon electron impact of bis (η5 ‐cyclopentadienyl) vanadium (III) derivatives of the Cp2 v(sr) type and cp2 VCl
Authors: Claude Georges S. , Tabacchi R. 
Published: September 2010

AbstractThe fragmentation upon electron impact of bis (η5 ‐cyclopentadienyl) complexes of Vanadium(III): Cp2V(SR) (R=CH3, isoC3H7, phenyl, benzyl) have been investigated. The first fragmentation pattern is characterised by the formation of stable ions: Cp2V1+, Cp2VH1+ and CpSR1+. Further decomposition of the metal‐containing ions can be explained in terms of valence change concept.
Optically active transition metal complexes, LXXI *). synthesis, characterization, and conformational analysis of pyridine‐imine complexes [C5H5 (CO) 2MoNC5H4CX=NCH (R1) (R2)]PF2 with X = H, CH3, and C6H5
Authors: Brunner Henri , Rastogi Devendra K. 
Published: September 2010

AbstractSix new complexes of the type [C5H5Mo(CO)2NN*]PF6 have been prepared by treatment of C5H5Mo (CO)3Cl with the Schiff bases NN*, derived from 2‐acetyl pyridine or 2‐benzoyl pyridine and chiral amines H2NCH(R1) (R2) with (R1) (R2) = (CH3)‐(C6H5); (C2H5) (C2H5), and (CH3) (C2H5). The Schiff bases NN* contain a chiral amine component in its racemic form (R')/(S'). Therefore, in combination with the Mo chirality (R) and (S) a mixture of diastereoisomeric pairs of enantiomers (RS′)/(SR') and (SS')/(RR') is obtained. The diastereoisomers are separated by fractional crystallization. Diastereoisomer equilibration was achieved by heating the compounds in acetone‐d6 at 80°C for 90 h. The diastereoisomers have been differentiated on the basis of their 1H NMR spectra. A conformational analysis in terms of a) chemical shift difference for the C5H5 signals and b) ratio of diastereoisomers at equilibrium indicates how the chiral carbon substituents arrange with respect to the ligand plane for the diastereoisomers differing at the Mo configuration.
Effect of sodium on the co/γ‐al2o3 system. influence of the preparation conditions and calcination temperature
Authors: Lycourghiotis A. , Defossé C. , Delmon B. 
Published: September 2010

AbstractThe conditions at which sodium used as a dope can modify the state of dispersion and nature of γ‐alumina supported cobalt oxide are investigated. The order of impregnation and the temperature of calcination after Na impregnation are shown to be essential factors.
Het verband tussen parameters voor verdunde en matig geconcentreerde oplossingen van macromoleculen. Toepassing op sedimentatiecoefficienten
Authors: Peeters F. A. H. , Smits H. J. E. 
Published: September 2010

AbstractAccurate determinations of the coefficient of sedimentation for fractions of polystyrene in toluene, above as well as below the critical concentration c* for molecular overlap, resulted in the following expressions for respectively the parameter for the concentration effect in dilute solutions, and the coefficient of sedimentation in moderately concentrated ones: ks=(5.9±0.3)XSo1–71±0.02 and S=(0.163±0.007)XC−(0.606±0.006) With these, we could check some relations of correspondency, suggested by Wales, with respect to S(c) at either side of c*. Because of the satisfactory result ‐ reliably calculated S(c) from the experimentally determined ks(So) ‐ Wales theory was modified and applied to the radius of gyration, the osmotic pressure and the viscosity.
Yttrium(III), lanthanium(III) and zirconium(IV) complexes of some bidentate schiff bases derived from hetero aromatic amines and salicylaldehyde
Authors: Abd El‐Hamide R. , Mahmoud M. R. , El‐Haty M. T. 
Published: September 2010

AbstractY(III), La(III), and Zr(IV) complexes with some heteroaromatic Schiff bases derived from salicylaldehyde and heteroaromatic amines, viz 2‐amino‐pyridine, 2‐amino‐4‐phenylthiazole and 2‐amino‐5‐phenyl‐1, 3, 4‐thiadiazole have been prepared, The structures of the complexes have been investigated by elemental analysis, the spectrophotometry molar ratio and continuous variation methods as well as infrared spectra. It is found that the complexes obtained are characterized by high coordination number.
Amino steroids ‐ functionalization of position 20 from position 18 in a pregnane system through a Hofmann‐Löffler process. predominant formation of 5α‐heteroconan‐3β‐ol
Authors: van De Woude G. , Biesemans M. , van Hove L. 
Published: September 2010

AbstractThe Hofmann‐Löffler sequence of reactions applied to 18‐methylamino‐5α‐pregnan‐3β‐ol led to Sα‐heteroconan‐3β‐ol (11, 20BF or 20R configuration) and to 5α‐conan‐3β‐ol (12, 20αF or 20S configuration, as in natural conanine derivatives) in a ratio of 8 to 1, to the exclusion of any other nitrogen containing cyclic system.
New results about the c26 sterols also concerning their possible origin
Authors: Boutry J. L. , Barbier M. 
Published: September 2010

AbstractStanols and particularly the C26 stanol 5, have been found to accumulate in an oil impregnated sediment. In connection with the possible origin of C26 sterols as deduced from this observation, model experiments using a C28 precursor (campestanol) have been performed. However, in the conditions of these experiments, the bacterial degradation of the side chain by a pool of marine bacteria does not lead to the expected steroid structures.
Dogger bank itch. 2. An allergic contact dermatitis
Authors: Carlé Jørgen S. , Christophersen Carsten 
Published: September 2010

AbstractDogger Bank Itch is an allergic contact dermatitis representing a severe occupational hazard among trawlermen of the Dogger Bank Area in the North Sea. Allergic sensitivity is acquired following exposure to the marine bryozoan Alcyonidium gelatinosum. The allergen has been identified as (2‐hydroxyethyl) dimethylsulfoxonium ion. The isolation, structure determination and synthesis of the allergen is discussed.
Electrochemical Studies on the Metal Complexes of Alizarin Fluorine Blue and Its 5‐Sulphonated Analogue
Authors: Qureshi G. Ali , Ireland N. 
Published: September 2010

AbstractPolarographic, cyclic voltammetric and microcoulometric techniques have been used to study the electrochemical nature of the binary and ternary comlexes of Alizarin fluorine blue and its 5‐sulphonated analogue. The conditional constants of certain metal complexes are evaluated and effort has been made to determine the exact compositions of these complexes. The pH‐effect on the E1/2 and id are discussed.
Phenyl Group Interchange in Gaseous Protonated α‐Phenylacetophenones
Authors: Maquestiau A. , Coupez C. , Flammang R. 
Published: September 2010

AbstractFluorine and carbon 13 labeling experiments show that the phenyl group interchange in metastable protonated α‐phenylacetophenones (methane chemical ionisation conditions) occurs through protonated oxirane and diphenylacetaldehyde intermediates.
Role of the 1/e1+α Epithermal Neutron Flux Distribution in the K0‐Method α‐Mapping of Reactor Thetis
Authors: De Corte F. , Moens L. , Simonits A. 
Published: September 2010

AbstractA survey is given of a recent study concerning the deviation of the 1/E1+α epithermal neutron flux distribution from the ideal 1/E‐shape.So as to preserve the accuracy of the k0‐comparator method for standardization in (n,Y) activation analysis, it was of vital importance to work out appropriate α‐correction procedures on the resonance integrals to be used. Attention is paid to the development and the optimization of new methods for experimental α‐determination, which can be generally applied by activation analysis laboratories.The study enabled a complete α‐mapping for the 17 irradiation positions of reactor Thetis (Gent). It is found that, to a good approximation, the epithermal flux distribution in channel 9 is following the ideal 1/E‐law, i.e. α=0.
Energy‐Dispersive XRF Analysis of Soils Using a 109cd Excitation Source and a Precision Optimization Method
Authors: Voutchkov M. , Op De Beeck J. 
Published: September 2010

AbstractAn energy‐dispersive XRF analysis method, using a 109Cd excitation source has been developed for routine analysis of minor constituents or trace elements of high atomic number, in a matrix of low atomic number elements, such that enhancement matrix effects are negligible. A simple linear relationship between analytical concentration and a pure experimental factor is obtained, using the double absorption‐thickness method, taking into account correctly all absorption matrix effects. The theoretical optimization of the final precision on the analytical results, as well as the practical application are discussed. As an example the method has been applied to analyse a series of soil samples, giving results in good agreement with other methods of analysis.
Preferential Solvation of Single Ions: The PH4ASPH4B Assumption for Single Ion Thermodynamics in Mixed Dimethylsulfoxide‐Water Solvents
Authors: Kim J. I. , Gomaa E. A. 
Published: September 2010

AbstractThe paper presents a study of the Ph4AsPh4B assumption as for verification of its plausibility for the determination of thermodynamic quantities of single ions in mixed dimethylsulfoxide (DMSO)‐water solvents. For discussion the solvation energy is considered as a composite of electrostatic and neutral components. The neutral components are replaced by experimental data of Ph4Ge and Ph4C which are proved to be equal, of their size and structure, to the reference cation and anion. The electrostatic components are obtained by calculation according to the theory in the literature. The results of the present investigation provide the conclusion that an assymmetric partition is preferred to an equal partition practiced in the literature. Based on the study, the standard free energies of transfer for single ions, Ph4As+, Ph4B, Cs+ and I−, are determined and for others, H+, Li+, Na+, K+, Rb+, Cl− and Br− evaluated from the data of salts known in the literature. Discussion is elaborated with solvation properties of individual ions.
Stability of Calcium‐Strontium Hydroxyapatite Solid Solutions in Aqueous Solutions at 25°
Authors: Verbeeck R. M. H. , Driessens F. C. M. , Thun H. P. , Verbeek F. 
Published: September 2010

AbstractPhase diagrams were constructed from phase equilibrium calculations for the quaternary system Ca(OH)2‐Sr (OH)2‐H3PO4‐H2O and for the system Ca(OH)2‐Sr(OH)2‐H3PO4‐HX(BOH)‐H20 at 25°. On the basis of these diagrams the stability field of solid solutions of calcium and strontium hydroxyapatite was derived. The calculations show the borderlines of the apatite field to be determined by the activity isotherms of the sparingly soluble phosphates CaHPO4.2H2O, Ca8H2(PO4)6.5H2O, β‐SrHPO4 or Sr6H3(PO4)5.2H2O depending on the pH and the molar cSr:cCa and cCa: cP ratios in the solution. The biological implications of these results are discussed.
La Chimie des Arômes: Les Hétérocycles
Authors: Vernin Gaston , Metzger Jacques 
Published: September 2010

AbstractHeterocyclic compounds are widely distributed in food flavours. They arise following two main ways:

enzymatic and fermentation reactions from primary precursors (proteins, lipids, anthocyanines, polyphenols, carotenoids, ribonucleotides…).
non‐enzymatic browning reactions between reducing sugars and α‐amino acids also called MAILLARD's reaction.
The thermal degradation of food components: sugars, amino acids, vitamins, trigonelline… constitutes another important source of heterocyclic compounds.The various steps of the MAILLARD reaction as well as the formation of furans, pyrroles, thiophenes, oxazoles, thiazoles, imidazoles, pyridines, pyrazines, lactones in these reactions are described.Owing to the great complexity of natural flavouring mixtures and model systems, the computer assisted synthesis and the realization of a bank of mass spectra provide a valuable help to identify heterocyclic compounds in food flavours.
Electroanalysis of Some of The Organic Substances and the Effect of Halide Ions on Their Determinations in Effluents
Authors: Ali Qureshi G. 
Published: September 2010

AbstractThe electroanalytical technique based on the coverage of bright platinum electrode with methanol, ethanol, butan‐1‐ol, iso‐propanol and phenol as a function of potential and bulk concentration of these compounds in 1M H2SO4 is shown. The interference due to halide ion in the determination of organic substance is reported.
The Synthesis of 1‐Phenyl‐|4,5|‐Decanes
Authors: van Parys Marc , Vandewalle Maurits 
Published: September 2010

AbstractThe synthesis of some substituted 1,8‐diazaspiro|4,5|decanes starting from l‐benzyl‐4‐oxo‐piperidine is described. This skeleton is isosteric to the 1,3,8‐triazaspiro|4,5|‐decane structure present in important neuroleptic agents.
Solvolysis of Cis‐ and Trans‐S‐Methyl‐Thiazolidinium Phenylalanine Cyclic Dipeptides
Authors: Anteunis Marc J. O. , Becu Chr. , Kolodziejczyk A. , Liberek Bogdan 
Published: September 2010

AbstractThe solvolysis of cis− and trans‐S‐methylthiazolidinium phenylalanine cyclic dipeptides (diketopiperazines) in H2O (D2O), CH3OH, CD3OD:D2O and DCOOD has been studied. Ring opening of the Thz rings occurs (i) exclusively at the δ‐position in the trans‐isomers, resulting in the corresponding cysteinyl‐phenylalanine diketopiperazine derivatives in good yields; (ii) only partly at the δ‐position in the cis‐isomers, resulting in more complex reaction mixtures. The regiospecificity of ring opening is lost when weaker nucleophiles but stronger bases are used and substantial amounts of eliminative ring‐opening by H‐α attack is noticed. Kinetic studies in the different solvent systems reveal that solvolysis bears SN2 character.
Pyridines. Partie IX‐Pluribenzylation de La S‐Collidine et de La Lutidine‐2,6
Authors: Compagnon Paul‐Louis 
Published: September 2010

AbstractA literature survey of the polymetalation of 2,6‐lutidine 2 shows different results about the site(s) of deprotonation and condensation with various electrophiles. This discrepancy prompts us to examine the polylithiation (PhLi 3 equivalents, Et2O) of s‐collidine 1, 2,6‐lutidine 2 and more briefly of 2,4‐lutidine 3. Polylithiation takes place exclusively at the methyl groups of the same position vs the ring nitrogen: 2‐and/or 6‐methyl of 1. The previous regioselectivity observed in the case of the monometalation in Et2O is maintained. From 1 and 2, polylithiation gives picolyl anions which lead by reaction with PhCH2Cl, simultaneously to mono‐, di‐symmetrical, di‐non‐symmetrical α‐derivatives, and tri‐and tetra‐symmetrical α,α'‐compounds; but no product is formed from a benzylic β‐anion. In the same way, the deprotonation of 2‐methyl‐6‐(2‐phenylethyl) pyridine 17 leads to 2,6‐bis (2‐phenylethyl) pyridine 19 and 2‐methyl‐6‐dibenzylmethyl pyridine 18, to the exclusion of the β‐compound 2‐methyl‐6‐(2,3‐diphenylpropyl) pyridine 21. The latter compound is formed in low yield, besides 19 and 18, in the conditions of the Tchitchibabine reaction (NaNH2, toluene). The structure of the benzylated compounds was established mainly from the 1H‐nmr data. No product was isolated which would result from the nucleophilic attack of the generated carbanions at the pyridine carbons.
Synthesis of 5‐Alkyl‐3,3‐Dimethyl‐1,2,4‐Cyclopentanetriones, Involving Hydrogenation of 2‐Acyldimedones and Polychlorination
Authors: De Buyck L. , De Pooter H. , Verhé R. , De Kimpe N. , Schamp N. 
Published: September 2010

Abstract2‐Alkyldimedones, obtained from 2‐acyldimedones, were converted into 5‐alkyl‐3,3‐dimethyl‐1,2,4‐cyclopentanetriones in 40‐70 & overall yields, calculated on dimedone (AlkylMe, Et, n‐Pr, n‐Bu and 1‐Bu). The synthesis involved ring contraction of 2‐alkyl‐4,4,6,6‐tetrachloro‐5,5‐dimethyl‐1,3‐cyclohexanediones to afford 2‐alkyl‐3,5,5‐trichloro‐4,4‐dimethyl‐2‐cyclopentenones, which were hydrolyzed to give the title products.
Contribution a L'Étude Électrochimique de Dérivés de L'Acide Mercapto‐2 Pyridine Carboxylique‐5
Authors: Lejeune R. , Vandenbalck J. L. , Patriarche G. J. , Lapière C. L. 
Published: September 2010

Abstract2‐methylthiopyridine‐5‐carboxylic methylic ester and 2‐methylthiopyridine‐5‐carboxylic acid have been studied by recent polarographic and voltammetric technics (3,4). These molecules are irreversibely reduced at the thioether site. When considering the direct current, alternative and the differential pulse polarograms compared to cyclic voltammograms, the behaviour of these compounds can be elucidated. The pH influence on each basic fonction proton exchange and the adsorption impact on this protonation are described. A complementary study as a fonction of concentration establish the optimal conditions to quantify these compounds by classical and differential pulse polarography.
Studies of Brazilian Marine Invertebrates. VIII. Zoanthosterol, a New Sterol from the Zoanthid Zoanthus Sociatus (Hexacorallia, Zoanthidea)
Authors: Kelecom A. 
Published: September 2010

AbstractThe new marine sterol zoanthosterol, 4α‐methyl‐5α‐ergosta‐24 (28)‐en‐3β‐ol, has been isolated, together with cholesterol and chalinasterol, from the zoanthid Zoanthus sociatus. The structure of zoanthosterol was deduced from spectroscopic data.
Desoxybenzoins from the Lithium Bromide‐Catalyzed Homologation of Aromatic Aldehydes with Phenyldiazomethane
Authors: Loeschorn Carol A. , Nakajima Masayuki , Anselme Jean‐Pierre 
Published: September 2010

AbstractDesoxybenzoins are obtained in good to excellent yields from the lithium bromide‐catalyzed homologation of aromatic aldehydes with phenyldiazomethane.