bluuebunny/crossref_metadata_2025_split huggingface dataset:
N.M.R. Experiments on Ketals IV. P.M.R. Spectra and Conformations of the Dioxolanes of 2,3‐Butanediol and Acetophenone
Authors: Anteunis M. , Alderweireldt F. 
Published: September 2010

AbstractThe dioxolanes of acetophenone and 2,3‐butanediol were prepared and the three possible isomers were separated by GLC. Structural assignment was based on physical and spectral behaviour. The magnetic anisotropy effect between cis‐1,2‐ and 1,3‐located methylgroups and/or protons is found to be in accordance with previously found values (1,6). The cis‐β‐phenyl interaction seems to cause a ca 0.20 ppm downfield shift of the ring proton, while this effect is about 0.06‐0.10 ppm downfield for a methyl group. A cis‐1,2‐dimethyl interaction on the contrary causes an upfield shift of about 0.12 ppm. The entire X3AA'X'3 patterns were solved using literature data (2,3). In the erythro compound no AX' coupling was found, while the previously proposed 2 correlation between JAA' and JAX' seems not to be fulfilled.
Étude du Comportement D'Isomères Géométriques Sous L'Impact Électronique V. Comparaison des données obtenues, par différentes méthodes, pour les 1,2‐diméthylcyclohexanes cis et trans
Authors: Natalis P. 
Published: September 2010

AbstractIonization potentials of cis and trans 1,2‐dimethylcyclohexanes have been determined by electron impact as well as appearance potentials of fragment ions first produced by breakdown of these molecules. Ionization efficiency curves treated by Warren's extrapolated difference method yield values in good agreement with those obtained by Lossing's semilogarithmic method.Identical ionization potentials and different appearance potentials of main fragment ions measured for both isomers can be related to the extra energy stored in the cis compound because of its steric conformation.Comparison is attempted between present electron impact data and photoionization data for the compounds investigated and qualitative agreement is found.
Étude Spectroscopique de Molécules Halogénées. III. Analyse conformationnelle en série cycloheptanique
Authors: Reisse J. , Ottinger R. , Chiurdoglu G. 
Published: September 2010

AbstractThe conformational analysis of halogenocycloheptanes was approached by infra‐red measurements in the ν (C‐Hal) region. For each derivative, the ν (C‐Hal) bands are attributed by solvent effect. It seems possible to describe halogenocycloheptanes as a mixture of three conformers in thermodynamic equilibrium.
The distribution ofm‐chloroaniline and the dissociation ofm‐chloroaniline hydrochloride
Authors: Aboul‐Seoud A. , Abou‐Egla B. , Bezirdjian K. 
Published: September 2010

AbstractFor the interpretation of kinetic measurements involvingm‐chloroaniline hydrochloride, the dissociation constant of the latter was determined at 5, 15, 25 and 35 °C, in sodium chloride solutions of 0 to 3 mole/1, using a modified distribution method (1). The distribution ofm‐chloroaniline between petroleum ether and aqueous sodium chloride solutions, was studied under the same conditions. The activity coefficients of the amine in aqueous solution, were determined at these conditions. The thermodynamic dissociation constant of the amine hydrochloride, at zero molality, was estimated at the different temperatures. ΔH, ΔF and ΔS were calculated.
Kinetics of laminar premixed methane — oxygen — nitrogen flames
Authors: Burke R. , van Tiggelen A. 
Published: September 2010

AbstractLa vitesse de propagation de la flamme, la température des gaz de combustion, et l'épaisseur de la zone de réaction ont été mesurées dans plus de trois cent mélanges de composition différente de méthane‐oxygéne‐azote.Cette étude expérimentale confirme le résultat d'investigations, faites par d'autres auteurs, sur la structure de la zone de réaction de la flamme se propageant dans quelques mélanges particuliers. On peut en dériver une énergie d'activation apparente ainsi que des ordres partiels par rapport au combustible et à l'oxygène.
N. M. R. Experiments on ketals. V1 the conformation of 2‐substituted 1,3‐dioxolanes
Authors: Weireldt F. Alder , Anteunis M. 
Published: September 2010

AbstractThe A2B2 system of the ring methylene protons in seventeen 2‐mono‐ and di‐substituted 1,3‐dioxolanes is analysed. The gem, cis and trans spin coupling constants and the shift values are reported. The results confirm the existence of a pseudo‐rotation (I to X) with favoured (pseudo) equatorial substitution.
An IR study of the 2‐(=NCOX)‐thiazoline group
Authors: Seth Paul Willem A. 
Published: September 2010

AbstractInfrared examination of compounds containing a 2‐(=NCOX)‐thiazoline group has revealed that the imino‐N atom bears proton accepting properties. The spectra of the bases exhibit bands at 1570 and 1477 cm−1. The first band is probably derived from the CO group while the low frequency band finds its origin most likely in the C…N group. The spectra of the corresponding hydrochloride salts show the CO band around 1740 cm−1 which represents a shift of 140 cm−1 to shorter wavelengths as compared with the corresponding bases. Furthermore, these spectra show a close resemblance in the 1750‐1500 cm−1 region to the spectrum of 2‐(acetylamino)‐4‐methyl‐thiazole‐HCl. We are therefore of the opinion that protonation has occurred at the imino‐N atom.
Synthèses et Propriétés des Bases de Schiff. II. — Propriétés acidobasiques et vitesses d'hydrolyse acide des α(p, N‐diméthyl‐aminophényl) iminobenzoylacétanilides (PIBA)
Authors: De Hoffmann E. , Bruylants A. 
Published: September 2010

AbstractCe travail est consacré à l'étude cinétique de l'hydrolyse de l'α(p,N‐diméthyl‐amino‐phényl) iminobenzoylacétanilide (PIBA), en milieu acide, ainsi qu'à celle des dérivés de substitution PIBAX et PIBAY; X est le substituant du noyau benzoyle et Y celui du groupe anilide: magnified image.Les constantes d'acidité de l'ion anilinium conjugué ont été déterminées par spectrophotométrie; les résultats suivants sont obtenus: log KaxKao = pxσ et log Kay/Kao = pvσ Kao = 2,206, px = 0,288 et py = 0,137 (25,5°C).Les constantes de vitesse ont été mesurées à diverses concentrations en acide, révélant un ordre unitaire par rapport à l'azométhine neutre et fractionnaire vis‐à‐vis de l'acide.Il n'a pas été possible de lier les constantes d'acidité et les constantes de vitesse d'hydrolyse par une relation simple.
L'Étude des Décompositions Thermiques par Spectrométrie de Masse. III. Acétaldéhyde
Authors: Collin J. E. , Delplace A. 
Published: September 2010

AbstractThe thermal behavior of acetaldehyde, at pressures of the order of 100 microns, has been investigated, up to 750°C, in a quartz reactor connected to a TOF Bendix mass spectrometer. In those conditions, no methane formation has been observed. Two important processes are the formation of acetylene and water, possibly by unimolecular decomposition of acetaldehyde, and the formation of ethylene and water, probably by decomposition of ethanol, a secundary product. The primary step of acetaldehyde decomposition is discussed, as well as the overall order of the reaction. At the low pressures used in this work, data are consistent with a first order reaction, rather than 3/2 or 2, and an activation energy of 57 kcal/m is proposed.
Chaleurs D'Interaction de Complexes par Liaison Hydrogène. 1. — Complexes Alcool ou Phénol — Pyridine
Authors: Neerinck D. , Lamberts L. 
Published: September 2010

AbstractHeats of formation of Hydrogen bond complexes between pyridine and alcohols or substituted phenols are measured in carbon tetrachloride solution by calorimetry. The obtained energies are compared with the acid ionization constants in water and the a values of the phenol substituents. Steric hindrance lowers the bond energy. However the heats of complex formation are linearly related to the frequency shift of the hydroxyl absorption brought about by the Hydrogen bond interaction.
Contribution A L'Étude des Composés Sesquiterpéniques. VII. Guaioxyde et bulnesoxyde. Détermination de leur structure
Authors: Ledoux P. , Vaterlaus B. P. , Chiurdoglu G. 
Published: September 2010

AbstractGuaioxide (III) and bulnesoxide (IV) were obtained from guaiol (I) and bulnesol (II), and their structures have been determined.
Acetylation of anthracene by the Friedel‐crafts reaction using nitrobenzene as the solvent
Authors: Bassilios H. F. , Salem A. Y. , Anous M. T. 
Published: September 2010

AbstractThe acetylation of anthracene by the Friedel‐Crafts reaction using nitrobenzene as the solvent leads, under certain conditions to pronounced 2‐substitution. It is liable to the effect of different factors. No diacetylation occurs. 2‐Acetylanthracene is also formed by the isomerisation of 9‐acetylanthracene. The effect of the solvent and the different factors are discussed. The preparation of 2‐acetylanthracene, 2‐acetylanthraquinone and anthraquinone‐2‐carboxylic acid are described.
Oxydation Entraînée des Hydrocarbures. II. Influence des sels de Cobalt
Authors: Rouchaud J. 
Published: September 2010

AbstractIn the autoinitiated oxidation of pure cyclohexane in the liquid phase at 150°C and under an initial partial pressure of oxygen ot 11kg/cm2, the salt of cobalt reduces the time of induction, but does not increase the rate of transformation. On the other hand, in the oxidation of the mixture cyclohexanecumene, the rate of transformation of cyclohexane is increased, and this increase is more pronounced by the addition of cobalt naphtenate. The induction period decreases with higher cumene or cobalt concentration. The differences between the observed and calculated effects, on the base of deduced kinetical relations, are interpreted as an increase in the chain branching degree when cumene is present. The stability of the cumylperoxydic radicals is related to the effect.
Détermination De La Structure Du 3‐OXO‐3,3a‐Dihydroguaiazulène, Produit De La Réaction De Dakin Sur Le 3‐Formylguaiazulène. Un Exemple Inhabituel De Tautomérie Cétoénolique
Authors: Fuks R. , Chiurdoglu G. 
Published: September 2010

AbstractThe Dakin reaction on 3‐formylguaiazulene (I) did not lead to the expected 3‐hydroxyguaiazulene (II). The structural study of the pale‐yellow crystalline compound, isolated in 60% yield, proves it to be 3‐oxo‐3,3a‐dihydroguaiazulene (IIIa), the ketonic tautomer of 3‐hydroxyguaiazulene. Chemical (reduction, Grignard reaction and hydrogenation) and spectroscopic investigations (IR, UV and NMR) are confirmatory to this conclusion. The NMR spectra have shown two structures to be present in solution. These are probably the two ketonic tautomers (IIIa and IIIb) possible for 3‐hydroxyguaiazulene. Preponderance of a ketonic non azulenic structure over its hydroxyazulenic tautomer is the first example of such a tautomery.
Excess Free Energies and Volumes of two Simple Binary Liquid Mixtures: Methane‐Krypton and Nitrogen‐Methane
Authors: Fuks S. , Bellemans A. 
Published: September 2010

AbstractThe excess free energies and volumes of the liquid systems: Methane‐Krypton and Nitrogen‐Methane, are obtained from total vapor pressure and density measurements respectively. The experimental results are compared to those available from other authors and briefly discussed in relation to the Average Potential Model of Solutions developed by Prigogine and coworkers.
Triterpènes X (): Spectroscopie de résonance magnétique nucléaire de composés triterpéniques. Influence de la substitution sur les fréquences de résonance des groupes méthyles en série Δ12‐oléanénique
Authors: Savoir R. , Ottinger R. , Tursch B. , Chiurdoglu G. 
Published: September 2010

AbstractA complete assignment of the NMR methyl frequencies of Δ12‐oleanene triterpenes has been achieved. A list of additive chemical shifts permitting a priori calculation of the methyl frequencies for various substituents has been established. The synthesis of some new oleanenic derivatives is described.
Cyclopentanones II. The Synthesis of 4‐alkyl‐5‐hydroxy‐1, 3‐cyclopentanediones
Authors: Compernolle F. , Vandewalle M. 
Published: September 2010

AbstractSpecific reduction methods for the 2‐carbonyl function of 3‐alkyl‐1, 2, 4‐cyclopentanetriones are described. On reduction with zinc‐hydrogen chloride in acetic acid the enol acetates of these triones yield a mixture of cis and trans isomers of 4‐alkyl‐5‐hydroxy‐1, 3‐cyclopentanediones. Sodium borohydride reduction of 3‐alkyl‐3, 5‐dibromo‐1, 2, 4‐cyclopentanetriones leads exclusively to the trans isomers. The obtained 4‐alkyl‐5‐hydroxy‐1, 3‐cyclopentanediones can be acylated at the 2‐position, as demonstrated by the synthesis of dihydrohumulinic acid A.
N. M. R. Experiments on Ketals. X: Temperature‐Dependent Chemical Shifts of Methoxyprotons in Alkyl‐Cem‐Dimethoxycyclohexanes
Authors: Tavernier D. , Anteunis M. 
Published: September 2010

AbstractThe chemical shift difference Δν of methoxyprotons of alkyl‐gem‐di‐methoxycyclohexanes is dependent on temperature. This dependence cannot be solely explained in terms of a chair‐chair equilibrium. Other effects must play a role. An earlier proposition for a half‐chair form in 4‐t. Bu‐1, 1‐dimethoxy‐cyclohexane (1) is retracted.
Long Range Phenomena I Long Range Coupling in Cyclopentane Compounds Through Chains Containing sp2 Carbon Atoms
Authors: Anteunis M. , Compernolle F. 
Published: September 2010

AbstractApart from the more frequently occurring long range coupling in homoallylic and allylic systems (i.e. H‐C‐C‐C=C‐H systems), an analogous but much smaller effect can be found when the double bond is partial. The magnitude in “pseudo‐homoallylic” systems
equation image
however can be as high as 1 cps, especially with substituents on the olefinic bond, containing p‐orbitals.The newly discussed long range mechanisms are illustrated by several examples (table).
Catalyse Homogène De L'Oxydation Des Hydrocarbures Liquides
Authors: Rouchaud J. , Mulkay P. 
Published: September 2010

AbstractLiquid cyclohexane has been oxidized by molecular oxygen under a partial pressure of 15–18 atm., between 140 and 160°C. Cyclic products are formed: cyclohexanone, cyclohexanol and dicyclohexyladipate. The non‐cyclic products are: adipic, glutaric and monocarboxylic acids. Higher yield in non cyclic products is obtained when soluble cobalt catalyzes the reaction (10−4 ion g Co, as naphtenate/1 cyclohexane). When supported Co2O3 is used as catalyst, 102 times higher concentration in cobalt is necessary to obtain the same results as with the soluble salt. This difference of activity is interpreted as the result of steric and electronic‐magnetic effects. With cobalt naphtenate, about 85% of the initial cobalt is precipitated before 10% of the cyclohexane has been oxidized. Results indicate that only the remaining dissolved catalyst influences the reaction. The comparison of the rates of oxidation to the yield in non cyclic products shows that the compounds of transition elements catalyze the isomerization of the peroxidic radicals. This mechanism applies as well to the homogeneous as to the heterogeneous catalysis.
L'Étude Théorique Des Propriétés Conductrices Des Semi‐Conducteurs Organiques
Authors: André J. M. , Gouverneur L. , Leroy G. 
Published: September 2010

AbstractThe LCAO method is used to calculate the electrical conductivity in a series of conjugated systems. The results, though qualitative, lead to an understanding of several factors responsible for the presence of an energy gap in the band structure.
Étude Théorique Des Dérivés Azotés Des Hydrocarbures Conjugués Alternants II. Les Dérivés Monoazotés Des Hydrocarbures Alternants
Authors: Leroy G. , Aussems C. , van Remoortere F. 
Published: September 2010

AbstractUsing parameters fitted to the pyridine spectrum, SCF calculations have been carried through for seven monoaza cyclic compounds. The results obtained are discussed in the light of available experimental data and attention is particularly drawn to the electronic spectra and the ionization potentials.
Étude De La Chloration De La 2‐Méthylcyclohexanone
Authors: Peters P. A. , Ottinger R. , Reisse J. , Chiurdoglu G. 
Published: September 2010

AbstractSynthesys of 2‐chloro‐2‐methylcyclohexanone, cis‐ et trans‐2‐chloro‐6‐methyl‐cyclohexanone, trans‐2,6‐dichloro‐2‐methylcyclohexanone, 2,6,6‐trichloro‐2‐methylcyclohexanone, and related deuterated compounds, are reported. Structural and stereochemical determinations are established on the basis of IR, UV. and NMR spectra.
Triterpénes XV [1]. Réductions De Diène‐Diones Oléanèniques Par L‚Hydrure De Lithium‐Aluminium
Authors: Tursch B. , Bartholomé C. , Daloze D. , Chiurdoglu G. 
Published: September 2010

AbstractLithium‐aluminium hydride reduction of diacetoxy‐12,19‐dioxo‐Δ9 (11),13 (18)‐21‐epi‐methylmachaerinate yields 3β, 19ξ, 21α‐trihydroxy‐28‐noroleana‐9(11),12,17‐triene. LAH reduction of acetoxy‐H.‐dioxo‐Δ9(11), 13(18)‐methyloleanolate affords a 3:1 mixture of 3β, 28‐dihydroxy‐12,19‐oxido‐Δ9(11), 13(18) ‐oleananeand 3β,19ξ‐dihydroxy‐28‐noroleana‐9(ll),12,17‐triene.
Calorimetric Determination of the Enthalpy of Formation of the 1:1 Chelates of the Tripositive Lanthanide Ions With N‐Hydroxyethylethylenediaminetriacetic Acid
Authors: Fuger J. , Merciny E. , Duyckaerts G. 
Published: September 2010

AbstractEnthalpy changes associated with the formation of the 1:1 chelates of the lanthanide ions with N‐hydroxyethylethylenediaminetriacetic acid have been determined by a calorimetric method at 25°C and μ = 0.1 (K.Cl). The various thermodynamic functions corresponding to the formation of the chelates are discussed in terms of the structure of these species and compared with literature data on the corresponding chelates of ethylenediaminetetraacetic acid.
Preparation of the Enantiomers of 2‐Carbobenzyloxyaminoadipic Acid and Their 1‐Benzylesters
Authors: Claesen M. , Vlietinck A. , Vanderhaeghe H. 
Published: September 2010

AbstractDifferent methods of synthesis of 2‐aminoadipic acid were examined. The enantiomers of this acid, obtained by enzymatic resolution of the chloroacetylderivative, were transformed into L‐ and D‐2‐carbobenzyloxyaminoadipic acids. The two isomers were also prepared by fractional crystallization of the D‐ and L‐threo‐1‐p‐nitrophenyI‐2‐amino‐1,3‐propanediol salts.The 1‐monobenzylesters of L‐, D‐, and DL‐2‐carbobenzyloxyaminoadipic acid were prepared by esterification with phenyldiazomethane. The corresponding ester could also be obtained by reaction of the triethylammonium salt of the acid with benzylbromide in dimethylformamide solution. The structure of the mono‐benzylester was proved by transformation into the 1‐benzyl‐6‐ethylester, from which 2‐aminoadipic 6‐ethylester was obtained by hydrogenolysis.
N‐Methyldihydrostreptomycin Synthesis, Structure, and Antibacterial Activity
Authors: Vanderhaeghe H. , Totté J. , Claes P. 
Published: September 2010

AbstractReductive methylation of dihydrostreptomycin yielded a new derivative, N‐methyl‐dihydrostreptomycin. By this reaction the N‐methyl‐L‐glucosamine fragment of dihydrostreptomycin is converted into N‐dimethyl‐L‐glucosamine. The structure of this derivative is confirmed by degradation and NMR spectroscopy. Methylation of the monomethylamino function of dihydrostreptomycin resulted in a complete loss of antibacterial activity.
Étude par R.M.N. De Haute Résolution de L'état Adsorbé. III. Mise en Évidence de Points de Congélation et Interprétation
Authors: Derouane Eric G. 
Published: September 2010

AbstractIn a former study (I), we have shown that an adsorbed system was to be considered as composed of three distinct phases on the N.M.R. viewpoint. In the present paper we discuss the problem of the freezing point of the adsorbate contained in the micro‐ and macropores. It is found that freezing points are considerably lowered as a result of interactions between molecules themselves, and between the molecules and the surface. The adsorbate, contained in the macropores, is found to be unperturbed and has a freezing point similar to that of the pure liquid. In the micropores, the lowering of the freezing point is of about 10 to 20 deg;C depending on the natures of both the adsorbate and the support. The phenomenon is found to be completely reversible, and a possible explanation is proposed in term of a lowering of the adsorbate activity in the micropores as a result of the interactions with the surface.It seems well established that N.M.R. provides a very easy tool for the determination of freezing points in the adsorbed state. An extension is also possible for the study of polymer swelling.
Complexes du Fer‐Carbonyle Avec L'acétylène et ses Dérivés. V. Structure de Fe2(CO)6 · (CH3C2CH3)2CO
Authors: Piron J. , Piret P. , Meunier‐Piret J. , van Meerssche M. 
Published: September 2010

AbstractThe structure of one of the products of the reaction between Fe2(CO)9 and CH3C  CCH3 has been determined by X‐ray diffraction. The monoclinic crystals belong to the space group P21/c. The dimensions of the unit‐cell are a = 8.34, b = 26.16, c = 8.31 Å,β = 112.4°, Z = 4. The complex can be formulated as: magnified image.
Synthesis of 5‐Isovaleryl‐3,3‐Dimethyl‐1,2,4‐Cyclopentanetrione, A Homologue of Tetrahydrohulupone
Authors: Verzele M. , De Pooter H. , Schamp N. 
Published: September 2010

Abstract3,3‐Dimethyl‐1,2,4‐cyclopentanetrione is prepared in high yield by hydrolysis and debromination of the easily accessible 2,3,5,5‐tetrabromo‐4,4‐dimethyl‐2‐cyclopentenone. Acylation with isovaleric anhydride affords the title compound.
Preparation of Octa‐n‐Methyl‐ and Tetra‐n‐Methylkanamycin
Authors: Claes P. , Vanderhaeghe H. 
Published: September 2010

AbstractTwo N‐methylated derivatives of kanamycin A were synthesized. The first compound, octa‐N‐methylkanamycin, was prepared by reductive methylation of kanamycin A. The second, tetra‐N‐methylkanamycin, was obtained by catalytic debenzylation of tetra‐N‐benzyl‐tetra‐N‐methylkanamycin. Both derivatives were devoid of antibacterial activity.
La Cryométrie de Quelques Systèmes Binaires: Coefficients D'Activité Thermodynamique Dans le Système Ternaire Nitrate de Lithium+Nitrate de Sodium+Eau et Dans les Système Binaires Associés
Authors: Vîlcu R. , Irinei F. 
Published: September 2010

AbstractThe present work studies the characteristics of the ternary LiNO3 + NaNO3 + H2O system and of the associated binary solutions LiNO3 + H2O and NaNO3 + H2O, in the concentration range 1, 5‐3 molal.The change of ion‐ion and ion‐solvant type interactions in ternary systems as regard to the binary systems, are evidenced by the δ and δo deviation functions.To calculate these functions use is made of the deviations from additivity of Gibbs thermodynamic potential in the ternary system. In the same time a method is presented for calculating Harned's coefficients and activity coefficients of individual electrolytes by means of deviation functions, δ.
L'Étude Théorique des Systèmes Periodiques: IV. Formulation Matricielle de la Méthode LCAO‐SCF‐CO
Authors: André J. M. , Delhalle J. , Leroy G. 
Published: September 2010

AbstractOn déduit une formulation matricielle générale de la méthode des orbitales cristallines autocohérentes (LCAO‐SCF‐CO). L'organisation du programme de calcul correspondant (POLYCOD) est décrite dans la dernière partie de ce travail.