bluuebunny/crossref_metadata_2025_split huggingface dataset:
Le Rôle des Complexes A Liaisons Hydrogène “Homéotopiques” Dans Les échanges Rapides Entre Protons
Authors: Huyskens P. , Zeegers‐Huyskens Th. 
Published: September 2010

AbstractIn some hydrogen‐bonded complexes, the bonding proton can occupy two positions, such as the motion from the first to the latter does not modify the general aspect of the complex. To this class belong, for instance, the ammonium‐amine complexes, the four‐centers transition complexes between OH and NH groups discussed by Brodskii, the cyclic dimers of carboxylic acids and so on. Quite generally the presence of such complexes with “homeotopous” bonds leads to a very fast exchange of the protons. The exchange rate is given by νexch=k[complex] wherekis the rate constant for the rupture of the hydrogen bond, with an order of magnitude of 109sec−1and [complex], the equilibrium concentration of the complex obeys, in first approximation to the law of mass‐action. The knowledge of the equilibrium constant can given information about the exchange rate. For the exchange between amines and alcohols, for instance, one can deduct from our experimental complexation constants, caracteristic exchange‐times of 10−8to 10−7sec. Alternatively one can predict the order of magnitude of complexation constants from experimental values of the exchange rate. From the rate constants of proton exchange between methyl ammonium salts and water, determined by Grunwald, Loewenstein, Meiboom and coworkers, one can deduct a order of magnitude of 0,1 to 1 M−1for the complexation constants between ammonium ions and amine. On the other hand, the exchange rates through such complexes appear to be little temperature dependent because the complexation energy acts in opposite sense onkand on the complexation constant. The only term that remains is the activation energy for the formation of the H‐bond, that may be very small. Experimental results of Conner and Loewenstein seem fit with this prediction.
Étude de La Position de la Bande CS des Thione‐Esters en Spectrographie Infra‐Rouge
Authors: Renson M. , Bidaine J. 
Published: September 2010

AbstractNous avons étudié les conditions les meilleures d'obtention des thione‐esters, et nous avons mis au point une méthode modifiée de préparation et de purification de ces substances.Nous avons ensuite étudié leurs spectres infra‐rouges et nous avons tenté d'y localiser la vibration CS. Celle‐ci se trouve avec certitude entre 1200 et 1270 cm−1; toutefois deux alternatives s'offrent à l'intérieur de ce domaine très encombré, et les arguments respectifs en faveur de chacune d'elles sont discutés.La position la plus probable est cependant 1205‐1218 cm−1 pour les thione‐esters aliphatiques, 1227 cm−1 pour les thione‐esters aromatiques.
Dosage Titrimétrique de la Thio‐Acétamide
Authors: Claeys A. , Sion H. , Campe A. , Thun H. 
Published: September 2010

AbstractLes conditions optimales pour la détermination de la thio‐acétamide par l'hypobromite de soude ont été déterminées. En travaillant dans un milieu de faible alcalinité, et en employant la méthode de standardisation en milieu identique, le nombre d'électrons échangés (n = 8) correspond à la réaction stochiométrique.Un contrǒle a démontré que la méthode proposée a une précision moyenne de 0,25%, et permet ainsi des titrages de solutions de thio‐acétamide d'une concentration de 0.01 molaire.
Polymorphism in Monobromoacetic Acid and the Diagram of State of Dichloroacetic Acid at Elevated Pressures
Authors: Glasgow Augustus R. , Timmermans Jean 
Published: September 2010

AbstractPiezometric measurements to 5000 atmospheres have shown that dichloroacetic acid occurs in only one crystalline form; monobromoacetic acid exists in three forms with triple points at about 50.5°C and 120 kg/cm2(liq, C I, C II) and 53°C and 260 kg/cm2(liq, C II, C III). The transitions C I to C II and C II to C III have negative temperature‐pressure coefficients (dT/dP) and occur only at elevated pressures. No example has been previously reported of an organic compound which has two successive solid transitions with negativedT/dP coefficients such as were observed for monobromoacetic acid.Values ofdT/dP, ΔH, and ΔS, calculated from the piezometric data are given for the fusion of dichloroacetic acid and for the two solid transitions and the fusion (C III, liq) of monobromoacetic acid. An evaluation of purity of the acids from time‐pressure data is discussed.
Dosage du Fluor II Composition du Chlorofluorure de Plomb en Fonction du Mode D'Addition du Réactif
Authors: Winkler P. Ed 
Published: September 2010

AbstractA method allowing, with an accuracy of one per thousand, the determination of chlorine and lead in the leadchlorofluoride precipitate, has been worked out. The precipitate, previously collected in filtring crucible and weighed, is then dissolved in an aqueous solution of aluminium nitrate, thus avoiding any deterioration of the glass material.Application of this method to the analysis of precipitates obtained in various conditions has shown the influence of the mode of introduction of the lead nitrate solution, producing the precipitation of the lead chlorofluoride. The modes only, for which the addition is very progressive and extremely slow, can give precipitates corresponding to the formula PbClF. The relative error in the determination of fluorine may thus be reduced to two per thousand for a quantity of fluorine present of about 50 mg. If the reagent is added too quickly, the precipitate has a composition which may be represented, by grouping the ions, in the form of a mixture of PbClF, PbCl2and PbClOH.
Études Conformationnelles VII. Sur L'épimérisation Des 4‐Tertiobutylcyclohexanols et Des 4‐Cyclohexylcyclohexanols Stéréoisomères
Authors: Chiurdoglu G. , Masschelein W. 
Published: September 2010

AbstractThe epimerisation of cis and trans isomers of 4‐tertiobutylcyclohexanol and of 4‐cyclohexylcyclohexanol is studied. The equilibration of these alcohols by catalytic methods may be interpreted by the thermodynamics of the conformational equatorial‐axial equilibrium of the hydroxyl group. This is not the case for the equilibration by the alcoholates of the corresponding alcohols.
Ionization and Dissociation of Molecules by Monoenergetic Electrons V. Acetylene and Ethylene
Authors: Collin Jacques E. 
Published: September 2010

AbstractL'étude détaillée des processus d'ionisation des molécules d'acétylène et d'éthylène a été entreprise au moyen d'un spectromètre de masse équipé d'une source d'électrons monoénergétiques. Certains processus d'apparition d'ions fragmentaires ont été également examinés.La discussion des résultats sur la base des structures électroniques des molécules considérées a permis de déduire un certain nombre de potentiels d'ionisation correspondant à des états excités des ions considérés.
Substitution Électrophile Aliphatique. Mécanisme et Vitesse de la Réaction D'Iododémétallation des Tétraméthyl, Éthyl, nPROPYL, nBUTYL et Allylétains
Authors: Gielen M. , Nasielski J. 
Published: September 2010

AbstractThe reactivity of a series of tetraalkyltins towards iodine has been determinated. The rate equation has been found to be v=k2. SnR4. I2 and the rate constant is not affected by added I‐. The reaction is an electrophilic substitution at a saturated carbon atom. The following rate constants have been observed: R=CH3, k2=6,81.m−1. sec−1; R=C2H5, k2=0,8; R=nC3H7, k2=0,1; R=nC4H9, k2=0,04.The CH3<C2H5<nC3H7<nC4H9 sequence is interpreted as being due to an increasing steric repulsion between the incoming and leaving groups.Tetraallyltin has further been found to react 300 million times faster than tetrapropyltin towards I2. An SE2′ mechanism, free from steric effects, is suggested to explain this very large difference.
Thermodynamic Properties of Some Metal Hexafluorides
Authors: Nagarajan G. 
Published: September 2010

AbstractThe thermodynamic properties such as heat content, free energy, entropy and heat capacity have been calculated for the molecules MoF6, WF6, IrF6, UF6, NpF6 and PuF6 for the ideal gaseous state at one atmospheric pressure up to a rigid rotator, harmonic oscillator approximation. The values have been calculated for the temperature range from 50° to 1600° K by using the observed fundamental frequencies for the above molecules.
Potential Field and Force Constants of Symmetrical Tetrazine
Authors: Nagarajan G. 
Published: September 2010

AbstractAn orthonormalized set of symmetry coordinates satisfying the transformation properties has been constructed for the planar s‐tetrazine molecule having the symmetry point group D2h. The F and G matrices have been deduced for both planar and nonplanar vibrations. With the existing infrared absorption fundamental frequencies the secular equations have been formed and solved to obtain a set of symmetry force constants.
Chaleurs de Combustion de Dérivés Cyclopropaniques et Pouvoir de Conjugaison du Groupe Cyclopropyle
Authors: Fierens P. J. C. , Nasielski J. 
Published: September 2010

AbstractThe heats of combustion of vinyl‐, ethyl‐, phenyl‐ and cyclohexylcyclopropane have been found to be respectively 772,8, 808,8, 1213,3 and 1317,8 Kcal/mole. These results clearly indicate that the ground state of “conjugated” cyclopropane derivatives is not stabilized by resonance; this is supported by HLSP quantum mechanical calculations, which give a resonance energy of 0,6 Kcal/mole in the case of vinylcyclopropane. The synthesis of phenylcyclopropane has been improved; a new compound, cyclohexylcyclopropane, has been prepared.
Phase Relations Involving Brochantite and Antlerite at Pressures to 100 Kilobars
Authors: Pistorius Carl. W. F. T. 
Published: September 2010

AbstractThe phase boundary representing the reaction brochantite ⇋ antlerite + tenorite + water has been followed to a pressure of 100 kilobars in the simple squeezer high‐pressure apparatus. The critical point brochantite (antlerite + tenorite + ice VII) antlerite + tenorite + vapour is situated at 65 ± 5 kilobars, 290 ± 10°C.
Potential Constants and Thermodynamic Functions of Isotopic Oxides of Nitrogen
Authors: Nagarajan G. 
Published: September 2010

AbstractBy using the observed zero‐order frequencies of isotopic oxides of nitrogen, the evaluation of potential constants on the basis of Wilson's group theoretical method and the calculation of molar thermodynamic functions for the temperature range from 200° to 2000°K on the basis of a rigid rotator, harmonic oscillator model have been carried out.
Étude, Par la Théorie du Champ Cristallin, de la Structure des Solutions Aqueuses des Éléments de Transition. I Scission des Termes dn Dans des Champs Faibles
Authors: Michielsen‐Effinger Janine 
Published: September 2010

AbstractA point dipole model is used to calculate the electronic energies of the first transition‐series ions when four, five or six coordinated. The calculation of energy levels is made for the ions of configuration 3dn in weak crystal fields of tetrahedral, square planar, square pyramidal and octahedral symmetries. A first‐order perturbation calculation is carried out on the free ion terms of the highest multiplicity arising from the ground state configuration. Russel‐Saunders zero order n‐electrons wave functions are calculated by the method of the angular momentum operators. The calculation yields energy levels expressed in terms of adjustable parameters depending on the nature of the cation, the nature of the solvent and the symmetry of the point charge distribution around the metal ion. The energy eigenvalues obtained will be used subsequently to determine the structure of the aqueous solutions.
Extraction des Lanthanides et des Actinides au Moyen D'Acide Dibutylphosphorique. II
Authors: Duyckaerts G. , Dreze P. H. 
Published: September 2010

AbstractLe mécanisme de l'extraction par l'acide dibutylphosphorique des lanthanides et des actinides trivalents est établi en tenant compte du partage du complexant et de sa dimérisation dans les diluants organiques. Les constantes de stabilité des dibutylphosphates de lanthanides et de certains actinides trivalents ont été calculées et l'extraction est discutée en fonction du nombre atomique.
Thermodynamic Functions of some Trigonal Bipyramidal Pentahalides
Authors: Nagarajan G. 
Published: September 2010

AbstractThe importance of the spectroscopic method of calculating the thermodynamic functions over that of the calorimetric method and the detailed procedure for the calculation of these functions have been given. By using the observed fundamental frequencies and molecular parameters, the thermodynamic functions have been calculated for the pentafluoride of stibium and the pentachloride of niobium molecules on the assumption of a rigid rotator, harmonic oscillator approximation for the temperature range from 100° to 1700°K.
Mean Amplitudes of Vibration of Some Tetrahedral XY4 Type Molecules‐Part I
Authors: Nagarajan G. 
Published: September 2010

AbstractThe general theory of mean‐square amplitude matrices has been briefly applied to the tetrahedral XY4 type molecule. The expressions for the twelve mean‐square amplitude quantities as linear combinations of the symmetrized mean‐square amplitude matrix elements have been given. The secular equations for the normal frequencies involving symmetry force constants and symmetrized mean‐square amplitude matrix elements have been obtained. The expressions for the generalized mean‐square amplitudes (mean‐square parallel amplitudes, mean‐square perpendicular amplitudes, and mean cross products) in terms of the Σ matrix elements have been given. For the molecules SiF4, OsO4, RuO4, CH4, CD4, CD4 and Cl4, the computed values of (1) mean‐square amplitude quantities, (2) generalized mean‐square amplitudes and (3) mean amplitudes of vibration at the temperatures T=O and T=298°K have been reported.
Préparation D'Isochromannones‐3 A Partir des Chlorures D'(o‐Acétyl‐ Eto‐Benzoyl‐Phényl) α, α Diméthylacétyle
Authors: Renson M. , Christiaens L. 
Published: September 2010

AbstractNous nous sommes efforcés sans succès de préparer les chlorures des acideso‐acétyl eto‐benzoyl‐phénylacétiques, et nous montrons que cet échec est lié à la présence d'hydrogènes mobiles sur le groupement–CH2–.Nous préparons en conséquence les acideso‐acétyl eto‐benzoyl‐phényl α, α diméthylacétiques ainsi que leur chlorure d'acide, afin d'en étudier la structure et les propriétés notamment par comparaison avec les chlorures d'acides homologues inférieurs.Nous montrons par spectrographie infra‐rouge que toutes les substances dérivant de ces chlorures d'acides possèdent la forme cyclique et appartiennent à la classe des isochromannones‐3.
Étude, Par Spectrométrie Infrarouge, de L'Association de L'Acide Mono‐n‐Butylphosphorique
Authors: Winand L. , Drèze Ph. 
Published: September 2010

AbstractInfrared spectroscopy has been used in order to obtain information about the structure of mono‐n‐butylphosphoric acid polymers (H2MBP) which exist in the liquid state.The spectra are compared with those of phosphoric acid, di‐n‐butylphosphoric acid (HDBP) and tri‐n‐butyl phosphate.Discussion of the results give evidence that two molecules of H2MBP associated in a polymeric unit are generally linked together by only a hydrogen bond and that each P=O group is linked by two hydrogen bonds.Tri‐n‐butylphosphine oxide associates with H2MBP and HDBP through its P=O groups. In the case of HDBP, it is easy to show that such interactions induce the breaking of the dimers.
Études Conformationnelles IX. Epimérisation des 4‐tertiobutylcyclohexanols stéréoisomères par le potassium dans du benzène. Analyse par la loi d'action des masses
Authors: Chiurdoglu G. , Gonze Melle H. , Masschelein W. 
Published: September 2010

AbstractThe epimerisation of the cis and trans isomers of 4‐tertiobutylcyclohexanol is studied quantitatively in the case of potassium in benzene as an agent. A general theory is formulated for the epimerisation of conformationally homogeneous cyclohexanols by monovalent agents. It has been shown that, in such conditions there is a linear relationship between the equilibrium titres of the trans derivative and the titre of the cyclohexanolate present. By extrapolation one may obtain experimental values of the conformational equatorial axial equilibrium of both the free alcohol and the corresponding alcoholates.
L'Effet des Radiations Électromagnétiques sur les Protéines I. Hydrolyse enzymatique de sérumalbumine aprés irradiation gamma en solution aqueuse
Authors: Colson C. , Fredericq E. 
Published: September 2010

AbstractBovine serumalbumin has been irradiated in aqueous solutions by gamma rays from a 60Co source, at dose rates varying between 5,000 and 60,000 rad per hour. An increase in absorbancy is brought about in the absorption band of aromatic aminoacids.A moderate increase in asymmetry is evidenced by viscosity measurements at total doses below 100,000 rad. For high doses, asymmetry strongly increases and precipitation takes place.The hydrolysis of irradiated samples by pepsin, trypsin and chymotrypsin has been measured by titration with a pH‐stat or by precipitation with trichloracetic acid. It was found that the rate of hydrolysis by pepsin and chymotrypsin decreased in proportion to the time of irradiation. This was attributed to the modifications produced in aromatic rings by irradiation, since the enzymes used are specific for bonds neighboring such aminoacids. On the contrary, trypsin, which does not have these requirements, is more active on irradiated samples. This could be related, partly at least, to the partial denaturation brought about in serumalbumin by gamma rays.
Synthèse des Sélénosemicarbazides Substituées III. Synthèse des sélénosemicarbazides substituées en 1
Authors: Collard‐Charon C. , Renson M. 
Published: September 2010

AbstractNous étudions la préparation de sélénosemicarbazides uniquement substituées en position 1; ces substances encore inconnues ne peuvent pas être préparées par la méthode générale utilisée dans le travail précédent; nous avons pu obtenir, par des méthodes particulières, des aryl‐1 sélénosemicarbazides.La préparation d'alcoyl‐1 sélénosemicarbazides n'a cependant pas pu être réalisée.
Essais de Synthèse de Substances Non Azotées Renfermant Une Liaison Sélénocarbonyle Localisation de la Vibration C=Se des Sélénone‐Esters en Spectrographie Infra‐Rouge
Authors: Collard‐Charon C. , Renson M. 
Published: September 2010

AbstractParmi les substances non azotées possédant une liaison double C=Se, nous avons réussi à préparer deux sélénone‐esters aromatiques. L'étude de leurs spectres infra‐rouges, comparée à celle des esters et thione‐esters, nous a permis de localiser vraisemblablement la position de leur vibration C=Se.
Potential Constants and Thermodynamic Functions of Iodine Pentafluoride
Authors: Nagarajan G. 
Published: September 2010

AbstractAn orthonormalized set of symmetry coordinates satisfying the transformation properties has been constructed for the iodine pentafluoride molecule having the tetragonal pyramidal structure with the symmetry point group C4v. Utilizing these symmetry coordinates and a potential function consisting of the ordinary valance force terms and central force terms, the elements of potential and kinetic energy matrices have been obtained. From the observed Raman and infrared fundamental frequencies the potential constants and thermodynamic functions such as heat content, free energy, entropy and heat capacity have been calculated for a rigid rotator, harmonic oscillator approximation.
The Complex of Humulone and 1,2‐Diaminobenzene
Authors: Anteunis M. , De Borger L. 
Published: September 2010

AbstractThe crystalline complex between humulone (I; R = CH2CH (CH3)2) and 1, 2‐diaminobenzene is completely dissociated in solution.It is shown that the complexation involves the alcohol group of the asymmetric carbonatom and a neighbouring carbonylfunction.
Équilibre Acide‐Base du Diméthylamino‐4′, α‐Cyanostilbène et de ses Dérivés de Substitution
Authors: Jerumanis S. , Bruylants A. 
Published: September 2010

AbstractLes auteurs ont étudié les variations de basicité du groupe diméthylaminé en fonction des divers substituants X sur un certain nombre de dérivés du N‐diméthylamino‐4′, α‐cyanostilbéne de formule générale:magnified imageEn milieu acide, en effet, les stilbènes colorés (B) fixent un proton et se transforment ainsi en ions aniliniums correspondants (BH+).Les mesures ont été effectuées sur une série de vingt N‐diméthylamino‐4′, α‐cyanostilbénes, comprenant le terme non substitué ainsi que ses dérivés monofluorés (2,3 et 4), monochlorés (2,3 et 4), monobromés (2,3 et 4), monoiodé (4), monométhyléthylés, 2, et 4), difluorés (2, 4 et 2, 6), dichlorés (2, 4 et 2, 6), dibromés (2, 4 et 2, 6) et diméthylé (3, 5).Les résultats montrent que la constante d'acidité varie avec le caractére polaire des substituants. En particulier, pour les dérivés méta et para, la corrélation de Hammett, log KαKαo=ρσ, est vérifiée dans les limites habituelles de précision. (Kαo=1,43. 10–2; ρ=0,515). Les données obtenues permettent en outre de chiffrer l'effet polaire (σ) du groupe cyanostyrilique (σ=0,529).
Studies on the Grignard Reaction IV. The Quantitative Determination of Grignard Reagent Concentration
Authors: D'Hollander R. , Anteunis M. 
Published: September 2010

AbstractIt is shown that the methods used to evaluate Grignard reagent concentration (acidimetry, argentometry, iodometry) give to high results. Two new methods are proposed, one based on the estimation of unreacted excess acetone (with hydroxylamine) and one upon a photometric determination of benzophenone excess. The latter only gives good results with aliphatic non‐tertiary derivatives.The methods can be extended to dialkyl magnesium compounds when enough magnesium bromide is added.
A Practical General Formula for the Calculation of Hydrogen‐ion Concentration of Aqueous Solutions of Acids and Bases
Authors: Claeys A. 
Published: September 2010

AbstractA general formula is proposed for the calculation of the hydrogen‐ion concentration of aqueous solutions of acids. This formula, containing the dissociation constant K and the analytical concentration No, and taking into account the dissociation of the acid (correction factor C) as well as the interaction with the solvent (correction factor X) is useful over the whole range of concentration and strength, and permits a rapid calculation in a simple way.An analogous formula is proposed for the calculation of the hydroxylion concentration of aqueous solutions of bases.
Contribution À La Spectrométrie Raman V. Etude De La Raie Raman Du Carbonyle:LA Mesure Du Coefficient De Diffusion
Authors: Michel Gilbert 
Published: September 2010

AbstractThe Raman bands of a large number of esters, ketones and aldehydes are investigated photoelectrically with a view of studying the intensity‐molecular structure correlation.Particular attention is drawn to the corrections of the observed intensities considered to obtain by the external and the internal standard methods the relative scattering coefficients able for this purpose.The relative scattering coefficient related to the CO, CC and C‐Carom. stretching bands and to the aromatic cycle breathing band are calculated from the maximum intensities.Some preliminar remarks are pointed out about the agreement of our values with those previously published by other authors.The intensity‐molecular structure correlation will be extensively discussed in further papers.
Étude Infra‐Rouge Des Substances Possédant une Liaison C=SE Adjacente à un ou Plusieurs Atomes D'azote
Authors: Sélénourées I. , Collard‐Charon C. , Renson M. 
Published: September 2010

AbstractNous avons étudié les spectres infra‐rouges d'une sélénouréea progressivement substituées, dont certaines ont dû être synthétisées pour la première fois.Nous y avons localisé la bande CSe dans les limites extrêmes 1083–1109 cm−1; nous discutons également les positions et l'identification des autres bandes principales, par comparaison notamment avec les spectres de sélénourées deutérées et d'une isosélénourée.