bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthèse D'Amino‐3 Oxadiazoles‐1,2,4
Authors: Eloy F. , Deryckere A. 
Published: September 2010

AbstractLa réaction de l'hydroxylamine sur les N‐cyanoamidines fournit des mélanges d'oxadiazoles‐1,2,4 isomères aminés en positions 3 et 5. Les amino‐3 oxadiazoles sont prépondérants en série aromatique, tandis que les composé aminés en position 5 se forment surtout à partir des amidines aliphatiques. Le mécanisme des réactions est discuté.
Étude par R.M.N. de Haute Résolution de l'état Adsorbé. I. Mise en Évidence D'un Système Nucléaire Triphasé
Authors: Derouane Eric G. 
Published: September 2010

AbstractAdsorbed systems were generally considered as composed of 2 distinct phases on the N.M.R. viewpoint. One phase corresponds to the first strongly perturbed monolayers, the other one being the liquid contained in the micro‐ and macropores of the support. We show that such an adsorbed system is in fact to be considered as composed of three N.M.R. phases wich correspond to the classical regions one distinguishes in classical studies of the adsorbed state; the first adsorbed monolayers, the compressed liquid in the micropores, and the unperturbed liquid in the macropores.Linewidths variations as function of the amount adsorbed are explained and transverse relaxation times have been determined for each of these phases. They show an increasing molecular mobility as the number of adsorbed layers is increased.
N.M.R. Spectra of Dihydrostreptomycin and Some of its Degradation Products
Authors: Claes P. , Vanderhaeghe H. , Totté J. , Slinckx G. 
Published: September 2010

AbstractThe N.M.R. spectra of dihydrostreptomycin (I) sulfate, N‐methyldihydrostreptomycin (II) trihydrochloride, α‐ and β‐methyl dihydrostreptobiosaminide (VI and VII), and dideguanyldihydrostreptomycin (VIII) were taken in deuterium oxide. The J12 values of the anomeric protons of the dihydrostreptose and the L‐glucos‐amine fragment were in agreement with the α‐L configuration of the two glycosidic linkages of the streptomycin molecule proposed by McGilveray and Rinehart [2].
Étude par R.M.N. de Haute Résolution de L'état Adsorbé. IV. Influence de la Température Sur L'état de L'adsorbat dans les Micropores non Saturés
Authors: Derouane Eric G. 
Published: September 2010

AbstractWe have shown previously that adsorbed systems were to be considered as composed of three nuclear phases undergoing fast exchange between themselves (1). A careful examination of the linewidth dependence as a function of the amount of adsorbate showed that one was able to determine the molecular orientation in the satured micropores (II). In the present article we deal mainly with a quantitative discussion of the temperature effects on both the adsorbate state and adsorbate N.M.R. linewidth before micropore saturation. The capillary condensation model is used. It enables one to get a theoretical relation which expresses the linewidth corresponding to that sort of adsorbed system. The use of that relation permits the evaluation of incremental energies due to the interactions of the adsorbed molecules with the surface and between themselves. Adsorption energies are derived for the different adsorbates, and are found to be in close agreement with calorimetric values.
Synthesis of Thiosultones
Authors: Goethals E. J. , Huylebroeck J. , Smolders W. 
Published: September 2010

AbstractThiosultones (cyclic thiolsulfonates) have been prepared by two methods: oxidation of cyclic disulfides with hydrogen peroxide in acetic acid and reaction of the corresponding chlorosulfonyl chlorides with sodium sulfide in dry methanol.Butanethiosultone and 4,4‐dimethylpropanethiosultone have been made using both methods, o.xylylenethiosultone using the first and propanethiosultone using the second method. The latter compound was unstable and polymerized upon standing. The other thiosultones were stable crystalline substances.
Theory on the Collapse Pressure of Mixed Insoluble Monolayers with Miscible Components
Authors: Joos P. 
Published: September 2010

AbstractUsing the chemical potential of each component in the surface and the bulk phases an equation was deduced, which allows to predict the collapse pressure of a mixed insoluble monolayer with miscible components, from the collapse pressure of each component separately. It was shown that the collapse of a mixed monolayer, is completely analogue to the distillation or crystallisation from a mixture. The equation deduced previously by Crisp is only of limited value. The present theory allows to investigate interaction at the interface. The theory was illustrated by a few systems cholesterol/cholanic acid, disteraoyllecithin/cholesterol, desoxycholic acid/tripalmitin and soybean lecithin/oleic acid.
Organometallic Compounds. X. P.M.R. Spectra of Tetrasubstituted Methyltin Derivatives: Steric Effects and the J(Sn–C–H) Coupling Constant
Authors: Gielen M. , De Clercq M. , Nasielski J. 
Published: September 2010

AbstractA redistribution of s‐character in the tin orbitals of the Sn–C bonds of methyl‐substituted tetraorganotins R3SnR' are expected to depend on the steric requirements of the R and R' groups and might be held responsible for the differences found for the J(Sn–C–H) coupling constants.
Configuration Électronique des Catalyseurs D'époxydation
Authors: Rouchaud J. , Mingiedi F. 
Published: September 2010

AbstractPropylene dissolved in benzene is oxidised by oxygen in the presence of catalytic amounts of chelates of heavy cations. The selectivity in epoxypropane induced by the catalyst is related to the structure of the ligand. The ratio selectivity in epoxypropane‐electronic structure of the ligand does not vary with the kind of the chelated cation. The peroxydic form of the catalyst being epoxidising, the same electronic configuration of the ligand induces the same capacity toward reversible epoxidation of the chelate.
Organometallic Compounds. XII. Topological Representations of Intramolecular Isomerizations of Five‐Coordinate Structures
Authors: Gielen M. , Nasielski J. 
Published: September 2010

AbstractTopological representations are presented to describe the intramolecular isomerization paths in five‐coordinate trigonal bipyramids. The most general case, involving five different ligands is described by the graph of figure 2. It is shown how variations in the complexity in the ligand system are reflected in the corresponding graphs.
Theoretical Study of Small Ring Compounds. I. Cyclopropene and Cyclobutene
Authors: André J. M. , Cl. André M. , Leroy G. 
Published: September 2010

AbstractIn this work, we report an all‐electron SCF—LCAO—MO computation for the ground‐state wave functions of the cyclopropene and cyclobutene molecules. The study of the ethylenic bond shows some delocalization of π‐like electrons to the methylene groups. Experimental results are discussed.
Alcaloïdes peptidiques. IX[1] la canthiumine alcaloïde ducanthium euryoidesBull. (rubiacées)
Authors: Boulvin G. , Ottinger R. , Païs M. , Chiurdoglu G. 
Published: September 2010

AbstractUn nouvel alcaloïde peptidique, la canthiumine1, a été isolé duCanthium EuryoidesBull. (Rubiacées). La nature des fragments qui le constituent —N,N‐diméthyl‐L‐phénylalanine,p‐hydroxy‐styrylamine, L‐proline et L‐thréo‐β‐phénylsérine — a été déterminée par hydrolyse acide de la dihydrocanthiumine2et par spectrométrie de masse. Le mode d'enchaînement de ces fragments est déduit du spectre de masse de la canthiumine.
NMR Experiments On Acetals. XIX. The NMR Analysis and Structure of 3‐Keto‐Lactose and β‐d‐Galactose
Authors: Anteunis M. , van Beeumen J. , De Bruyn A. , De Ley J. 
Published: September 2010

AbstractThe chemical structure of the glucoside‐ulose O‐β‐D‐xylo‐hexopyranosyl‐3‐ulose‐(1 → 4)‐D‐glucopyranoside (trivial name: 3‐keto‐lactose) is studied by nuclear magnetic resonance in deuterated dimethyl sulfoxide. The technique of multiple irradiation allows the identification of most of the signals in the spectrum (fig. 2). informative data are also obtained from the spectrum of β‐D‐galactopyranose (2) and methyl O‐β‐D‐ribohexopyranoside‐3‐ulose (3) (trivial name: methyl β‐3‐keto‐D‐glucopyranoside).The lack of a free carbonyl function in 3‐keto‐lactose is due to the presence of the hemiacetal which is formed on crystallizing the compound from methanol. The hydroxyl group at the anomeric carbon atom has the β‐configuration (1). It is suggested that this ketosugar prevails dominantly as the hydrate when it is prepared from aqueous solutions.
Comportement Anormal Lors D'Une Réaction de Reformatsky. Obtention de Dérivés du Benzo(b) Thiophène et du Benzo(b) Sélénophène
Authors: Ruwet A. , Renson M. 
Published: September 2010

AbstractExamination of the abnormal Reformatsky reaction on o‐methylthio and o‐methylselenoacetophenones shows the influence of SCH3 and SeCH3. When ethylbromacetate is used, the sulfur or selenium atoms are first attacked but ethyl α‐bromopropionate gives the desired cinnamic acids. Ethyl bromacetate leads to benzo(b)thiophene and benzo(b)selenophene compounds. When we first form the organozincic derivate, cinnamic acids are again obtained.
Formation de Chromones (O,S,Se) et D'Autres Dérivés par Action du Dicétène sur le Phénol, le Thiophénol et le Sélénophenol. Contribution â L'étude des Réactions de Pechmann et Simonis
Authors: Ruwet A. , Janne D. , Renson M. 
Published: September 2010

AbstractThe Pechmann and Simonis reactions are investigated with phenols (O, S, Se). Thio and selenophenols give thio‐1 and seleno‐1 chromones (Simonis reaction). Several cyclizing agents are studied. Ethyl acetylacetate is replaced by diketene. They give the Simonis reaction. From diketene we synthesize phenyl acetylthiol and selenolacetates which possess thiol or selenolester function. The cyclization produces rearrangement and leads to Simonis reaction. These 2 new ways give also chromones from oxygen compounds. We don't isolate thio‐1 and seleno‐1 coumarins. However, we obtain dimethyl‐2,6 phenylselenolcarboxylate‐3 γ‐pyrone which is yet converted to seleno‐1 chromone. We discuss all these results: the Pechmann and Simonis reactions intermediates are to be reconsidered, especially phenyl acetylacetates (O, S, Se).
Étude du Spectre ir des Thio‐1 et Séléno‐1 Coumarines et des Dérivés Thio‐2 Correspondants. Comparaison Avec les Thio‐1 et Séléno‐1 Chromones Isomères
Authors: Ruwet A. , Renson M. 
Published: September 2010

AbstractInfrared spectra of coumarins (O, S, Se) and chromones (O, S, Se) in several solvents and of their complexes with Lewis‐acids are examined. The carbonyl band of thio‐1 and seleno‐1 coumarins is complex, abnormally low and not pure. A methyl group in position 3 gives important lowering of the CO. Infrared spectra of thio‐1 and seleno‐1 coumarins are very similar and constitute a rapid identification of isologous seleno‐1 coumarins. The thio‐1 and seleno‐1 chromones possess very different spectra, except the carbonyl region. There is doubt for the CS vibration because the formation of dithiocoumarins and thio‐2 seleno‐1 coumarins leads to 2 strong bands near 1000‐1150 cm−1. The CC is approached by comparison of coumarins (O, S, Se) with thio‐2 derivates. Interpretation of many results is possible by the hypothesis that a polar form occurs partly in thio‐1 and seleno‐1 coumarins, in dithiocoumarins and thio‐2 seleno‐1 coumarins, in thio‐1 and seleno‐1 chromones.
Synthèses de Telluroéthers Arylaliphatiques Substitués en Ortho par Différents Groupements Fonctionnels Carbonylés Préparation et Étude des Propriétés Chimiques de L'o‐méthyltellurobenzaldéhyde
Authors: Piette J. L. , Renson M. 
Published: September 2010

AbstractLa réaction entre l'o‐diéthoxyméthyl phényllithium et le tellure commercial a été appliquée avec succès à la préparation de l'o‐butyltellurobenzaldéhyde et de l'o‐méthyltellurobenzaldéhyde. À partir de cette dernière substance en particulier nous avons pu mettre au point les conditions de réaction de transformation du groupement aldéhyde de manière à obtenir pour la première fois des telluroéthers du type arylaliphatique substitués dans la position ortho par la plupart des groupements fonctionnels simples de la chimie organique.
Energy Level Diagrams of the “NiAs”‐, “Pyrite”‐ and “Spinel”‐Type Sulfides of Fe, Co and Ni
Authors: Pauwels L. J. 
Published: September 2010

AbstractThe crystallografic, magnetic and electrical data from literature, and results of own electrical resistivity measurements have been used to develop for the sulfides of Fe, Co and Ni, qualitative energy level diagrams, allowing a consistent interpretation of their properties. The development is made in terms of ligand‐field theory as well as band theory. The importance of covalent cation‐anion‐cation ** interaction is emphasized.
Free Energy, Enthalpy and Entropy Changes of the Ag (I) Complexes of Some ω‐Aminocarboxylic Acids
Authors: van Poucke L. C. , Thiers G. F. , Herman M. A. , Eeckhaut Z. 
Published: September 2010

AbstractThe acidity constants of the ω‐aminocarboxylic acids with n = 1,2,3,4,5 and the stability constants of the Ag(I) complexes of the corresponding aminocarboxylates were determined at 0°, 15° and 40°C in o.5 M KNO3. From this and the same data at 25°, reported previously, the free energy, enthalpy and entropy changes involved in complex formation were calculated using the temperature coefficient method. The same thermodynamic functions were also obtained from calorimetric data.
Hydroxy‐4 Thio‐1 et Séléno‐1 Coumarines voie Nouvelle de Synthèse
Authors: Ruwet A. , Draguet C. , Renson M. 
Published: September 2010

AbstractReaction of thio and selenophenols with malonic acids in polyphosphoric acid leads to 4‐hydroxy 1‐thio and 1‐seleno coumarines. This new synthesis is compared with other ways.
Étude par Diffraction‐X de Quelques Composés du Système Nicote Obtenus par Synthèse Thermique
Authors: de Meester de Betzembroeck P. , Naud J. 
Published: September 2010

AbstractWe have studied the compounds with metal/tellurium ratio less or equal to unity in the ternary system NiCoTe.The limits of the homogeneity range of the hexagonal (Ni, Co)1–xTe phase have been fixed for different Ni/Co ratios.The compounds formed in the series (NiλCo1–x)0,75 Te and (NixCo1–x)0,50 Te and their cristallographic parameters have been determined.
Propriétés Magnétiques et Schémas Électroniques des Séléniures et des Tellurures de Co et de Ni
Authors: Vandenbempt E. , Pauwels L. , de Clippeleir K. 
Published: September 2010

AbstractL'étude de la susceptibilité magnétique en fonction de la température indique que les séléniures et tellurures de Co suivent la loi de Curie‐Weiss dans un grand domaine de température, tandis que les composés de Ni possèdent un comportement magnétique totalement différent: leur susceptibilité est quasi indépendante de la température (paramagnétisme de Pauli).Par combinaison de nos résultats avec des données cristallographiques et électriques, nous avons déduit des schémas électroniques possibles pour ces composés.
NMR Experiments On Acetals. Part 30. Cyclopentanones VI≠. The Reaction Of 3‐Methyl‐1,2,4‐Cyclopentatrione With Ethylene Glycol A Case Of An A Typical Long‐Range Coupling
Authors: Anteunis M. , Vandewalle M. , van Wijnsberghe L. 
Published: September 2010

AbstractReaction of ethylene glycol with 1,2,4‐cyclopentatriones (and other pentacyclic α‐diketone systems) results in a mixture of two isomers: a bisdioxolane and the thermodynamically more stable tetraoxadecalane (naphtodioxane). In acidic conditions both systems may be interconverted. Chemical and PMR spectroscopic evidence for the structures is advanced. In one case the hydrolysis of a tetraoxadecalane system leads to a monodioxolane derivative of an α‐dione.An anomalous long‐range PMR effect through four bonds (contraining sp2 hybrirds) is observed in the cyclopentanone moiety of 1,2‐bisethylenedioxy‐3‐methyl‐4‐cyclopentanone.
Study of the Kinetics, Intermediates and Product Distribution in the Synthesis and Decomposition Reactions of Thiourea Derivatives
Authors: Vanassche W. , Hoornaert G. 
Published: September 2010

AbstractThe solvent‐effect together with the influence of substituents in the aryl group on the yield of isothiocyanates in the decomposition of N‐mono aryl thioureas can partly be explained by solvent‐ and substituent‐effects on a consecutive reaction of two decomposition products amine and isothiocyanate. A more detailed investigation of this step, which is representative for the reaction scheme of thioureas, shows that reactions of aromatic amines with aryl isothiocyanates are characterized by an equilibrium limiting the yield of the product NN′ diaryl thiourea. Both amine and product seem to effect about equal catalytic influences on both steps of the equilibrium.From a study of the solvent‐effect on the reaction rate, it can be concluded that besides the unspecific factors, polarity and polarisability, also association‐effects and catalytic activities of the solvent must be taken into account.The considerable influence of the basicity of the amine on the reaction rate together with the pronounced effect of substituents in the phenyl isothiocyanate shows that the nucleophilic attack of the amine on the isothiocyanate must be the rate determining step; this view is in agreement with the low value for the isotope‐effect. The whole of the data can be correlated by assuming a reaction scheme wherein amine attacks the isothiocyanate both as a dimeric form and a monomeric form complexed with reaction product or solvent.
Conductivité électrique Du Picrate De N‐Butylammonium Dans Les Mélanges Eau Ou Alcool‐Dioxanne Et Nitrobenzène‐Benzène
Authors: Macau J. , Lamberts L. 
Published: September 2010

AbstractThe conductance of dilute solutions of n‐butylammonium picrate has been measured in water or ethanol‐dioxane mixtures and in nitrobenzene‐benzene mixtures. The data were analysed by the Fuoss conductance theory. The conductometric behavior of the salt in the different solvent mixtures has been discussed. The comparison suggests that solvation of the ions in hydrogen bonded solvents greatly lowers ion‐pairing. Points of the logarithm of the association constant against reciprocal dielectric constant lie on a straight line for the three solvent mixtures. The contact distance values obtained from the slopes are a σ 6 Å.
Attempted Synthesis of a Phosphaferrocene
Authors: Braye E. H. , Joshi K. K. 
Published: September 2010

AbstractPotassium 2,3,4,5‐tetraphenylphosphol‐l‐ide (I) reacts with cyclopentadienyldicar‐bonyliron iodide yielding cyclopentadienyldicarbonyliron tetraphenylphosphol‐l‐ide (II), which could not be converted into a phosphaferrocene by thermal treatment.
The Influence of Oxygen on the Decomposition of Ammonium Persulfate
Authors: Liegeois J. M. 
Published: September 2010

AbstractThe decomposition of ammonium persulfate has been investigated in buffered solution with either purge of nitrogen, or saturation with oxygen. A decrease of the decomposition rate is observed when oxygen is forced to stay in the solution, the most pronounced in the second stage of the decomposition experiment. In the first stage, a higher rate of decomposition is observed which does not depend on the presence or not of oxygen. This can be due partly to the suppression by oxygen of an induced decomposition mechanism. The other part of the effect is explained by a reversible reaction of decomposition and a decomposition mechanism which involves the intervention of water. A kinetic equation is deduced which explains other results given in the literature.
Alcaloïdes Pipéridiniques II. Structures de la Prosopine et de la Prosopinine, Alcaloïdes du Prosopis Africana (Guill. et Perr.) Taub. [1]
Authors: Khuong‐Huu Qui , Ratle Georges , Monseur Xavier , Goutarel Robert 
Published: September 2010

AbstractIn a preliminary note [1] we established the plane structure of the prosopine 1,2‐hydroxymethyl 3‐hydroxy 6‐dodecyl 11°‐hydroxypiperidine and the prosopinine 8, 2‐hydroxymethyl 3‐hydroxy 6‐dodecyl 10°‐keto piperidine, alkaloids isolated from Prosopis africana (Guill & Perr) Taub.This paper contains the study of the reduction products of the pyrrolidine 18b and the establishment of the relative and absolute configurations of these two alkaloids. The experimental part involves the details for the determination of these structures and also the extraction method of these two alkaloids as well as the new alkaloids: prosophylline, prosafrine and the prosafrinine isolated from leaves of P. africana and isoprosopinines A and B extracted from roots and stem bark of the same plant. The establishment of the structure of the new five alkaloids is the subject of the next paper.
Mechanism of Chlorite Oxidations Part I. Kinetics of the Oxidation of Formaldehyde by Chlorite Ion
Authors: Kudesia V. P. 
Published: September 2010

AbstractThe kinetics of oxidation of formaldehyde by chlorite ion in aqueous solution has been studied. The reaction is found to be of the first order with respect to formaldehyde and first order with respect to chlorite ion. Arrhenius equation is found to be valid for the reaction between 25° and 55°. The values of activation energy, ΔE≠; frequency factor, A; heat of activation, ΔH≠; entropy of activation, – ΔS≠ and free energy of activation, ΔG≠ (at 25°) are found to be 15.86 kcals/mole, 9.42 ± 107 l. mole−1 sec−1, 15.92 kcals/mole, 10.7 e. u. and 12.7 kcals/mole respectively.
La Déshydrohalogénation des Dérivés Halogènes de L'Éthylène. I. Étude Théorique Préliminaire par la Méthode CNDO
Authors: Leloup Geneviève , Leroy Georges 
Published: September 2010

AbstractOn étudie théoriquement les réactions de déshydrohalogénation des dérivés fluorés et chlorés de l'éthyléne par la méthode CNDO/2 de POPLE. Dans cette optique, on calcule les acidités thermodynamiques de ces composés ainsi que les chemins de réaction des éliminations cis et trans. L'analyse des résultats obtenus, grandeurs de structure et propriétés énergétiques, conduit à attribuer la préfférence trans à L'énergie d'activation de l'Elimination de l'halogène.
Formal Properties of Stereoisomerizations of Pentacoordinate Complexes. I. General Ligand Partition
Authors: Brocas J. , Willem R. 
Published: September 2010

AbstractTrigonal bipyramidal complexes may undergo rearrangements without bondbreaking. We propose in this paper a model which describes the kinetic behaviour of the most general ligand partition [where all ligands are different) of the trigonal bipyramid. It unables us to derive the multiplication table of the rearrangement mode operators and to diagonalize them by the same linear transformation. Relaxation times and time evolutions are calculated for the five possible isomerization modes.
Potential Constants of Iodine Heptafluoride
Authors: Srinivasan G. J. 
Published: September 2010

AbstractA most general harmonic potential energy function has been assumed for the pentagonal bipyramidal XY7 type of molecules belonging to the symmetry point group D5h and an attempt has been made to evaluate a complete set of potential constants of Iodine Heptafluoride by Wilson's F‐G matrix method and by making use of redundancy constraints obtained from the redundant symmetry coordinates.
Study of The Decomposition of Cyclobarbital (PhanodormR)
Authors: Willems G. , De Backer D. , Bouché R. , De Ranter C. 
Published: September 2010

AbstractThe cyclobarbital 2 (see formula fig 3) deteriorates when stored, due to a photochemical oxidation process. The components thus formed were separated by column chromatography and for the most important one, a structure determination was carried out. From NMR‐data the formation of 5‐(6‐oxo‐l‐cyclohexen‐1‐yl)‐5‐ethyl‐barbituric acid 1 (see formula fig 2) was concluded.
Oxidation products of hop bitter acids. Part VII. A further five‐membered ring product from the oxidation of colupulone
Authors: van Den Bossche R. , Anteunis M. , Verzele M. 
Published: September 2010

AbstractOxidation of colupulone (I) produces a complex mixture, separation of which by counter current distribution gives the spiro compound IV. Support for this structure comes mainly from 1H‐N. M. R. and mass spectral data.