bluuebunny/crossref_metadata_2025_split huggingface dataset:
Addition of chlorine atom on vinyl chloride
Authors: Olbregts J. 
Published: September 2010

AbstractThe competitive photochlorination of vinyl chloride and ethane has been studied at 322°K and permits one to measure k2 = 1010 mole −11 sec −1 for the rate constant of the addition of a Cl atom on vinyl chloride. This value is compared with those obtained for other chlorinated ethylenes and is discussed with respect to recent theoretical calculations.
Cyclopentanones. X A novel synthesis of (dl)‐prostaglandin F1α
Authors: De Clercq P. , Vandewalle M. 
Published: September 2010

AbstractA novel total synthesis of (dl)‐prostaglandin F1α methyl ester is described. The 2,3‐dialkyl‐1,4‐cyclopentanediol system is obtained by the reduction of an appropriate 2,3‐dialkyl‐4‐hydroxy‐2‐cyclopentenone. The facile conversion of the most abundant isomeric cyclopentanediol, with the all trans relation of the four substituents to a δ‐lactone enables the creation of the required prostaglandin configuration and the construction of the C‐12 side chain. Extensive spectroscopic data are included.
Radiation Chemistry of Polycrystalline 1‐Chloropropane at 77 °K
Authors: De Jouge D. , Ceulemans J. 
Published: September 2010

AbstractThe radiation chemistry of polycrystalline 1‐chloropropane at 77°K has been studied, with special emphasis on the influence of the irradiation time. The most important dose effect is a very marked decrease of the yield of hexane as a function of the dose. The concentration of this product even passes through a maximum at high doses. A comparison is made with dose effects in glassy 1‐chloropentane; the most important differences are additional positive dose effects on certain dichloropentanes and dichlorodecanes in 1‐chloropentane. Two distinct processes appear to be responsible for dose effects in irradiated chloroalkanes at 77°K. The first is the reaction of mobile hydrogen atoms with neutral radicals, causing a decrease of the yield of these radicals in function of the dose. The second is charge transfer to radicals and olefins, which were formed in an earlier stage of the radiolysis. Both effects are present in glassy 1‐chloropentane but only the first does manifest itself in polycrystalline 1‐chloropropane. This may be due to a greater range of the secondary electrons or to better migration possibilities of chloride ions in glassy 1‐chloropentane than in polycrystalline 1‐chloropropane. In view of other experimental results, the last explanation seems to be the most plausible.
Determination of the Ash Content of Coal on the Basis of its Chemical Composition
Authors: Block C. , Dams R. 
Published: September 2010

AbstractAn attempt was made to calculate the ash content of Belgian coals, from the analytically determined concentrations of silicon and aluminium. Simultaneously the total oxygen content of the coals was determined. Silicon and oxygen were determined by 44 MeV neutron activation analysis; aluminium was determined by reactor neutron activation.The precision of the ash content calculated on the basis of the silicon and aluminium concentration is generally better than respectively 8% and 12%. A precise estimation is not possible from the oxygen concentration. The validity of the method has been investigated for samples of different origin. The variations of the oxygen content are not correlated with the variations of the ash content. This is expected from the important contribution of organically bound oxygen.
Nuclear Magnetic Resonance Experiments on Multisulfur Heterocycles: 5‐Methyl‐1,2,3‐Trithiane
Authors: Anteunis M. , Goor G. 
Published: September 2010

AbstractThe aliphatic region in 5‐Me‐1,2,3‐trithiane takes, at least, an ideal chair and the ΔG‐value, found by low temperature 1H n. m. r., is 1.0 Kcal/mole
Comparative Carbon‐13 Nuclear Magnetic Resonance Study at 67.9 MHz on Lysozyme (Human and Egg‐White) and α‐Lactalbumin (Human and Bovine) in Their Native and Denatured State
Authors: Binst Georges Van , Biesemans Monique , Barel A. O. 
Published: September 2010

AbstractA first detailed comparison of the 13C spectra at high field of two lysozymes (human and egg‐white) and two α‐lactalbumins (human and bovine milk) is presented. Assignments were made on most of the resonance peaks in the aliphatic and aromatic regions of the denatured proteins. The relative peak intensities clearly demonstrate the differences in the amino acid composition of the related proteins. The broadening and the complexity of the spectra of the native proteins reflect the non equivalence of the chemical groups in the folded conformation. The usefulness of 13C nmr spectroscopy in the study of the interaction between small molecules and proteins was tested on N‐acetylglucosamine in the presence of lysozyme.
Fragmentation D'Azoles Sous L'Impact Électronique. VIII. Isomérisation du benzoxazole et du 1, 2‐benzisoxazole avant dégradation
Authors: Maquestiau A. , van Haverbeke Y. , Flammang R. , Pierard J. 
Published: September 2010

AbstractBenzoxazole and 1, 2‐benzisoxazole are isomerized in an o‐cyanophénol structure before degradation (losses of CO and HCN) as evidenced by analysis of metastable ions abundances and shapes.
Fragmentation D'Azoles Sous L'Impact Electronique. IX. Isomérisation du benzothiazole avant dégradation
Authors: Maquestiau A. , van Haverbeke Y. , Flammang R. , Pierard J. 
Published: September 2010

AbstractThe M‐HCN+. ion observed in the mass spectrum of benzothiazole is the result of two degradation processes:i) specific fragmentation of the heterocyclic part of the molecule and ii) isomerisation into an o‐mercaptobenzonitrile structure which eliminates HCN and CS. This latter process predominates for low‐energy molecular ions.
Effet De La Temperature Sur Les Rendements Des Produits Lourds Dans La Radiolyse Be L'hexane Normal Par Des Electrons Acceleres
Authors: Fontaine R. , Tilquin E. , Claes P. 
Published: September 2010

AbstractLiquid hexane was irradiated by electrons at temperatures ranging from −60° to + 60°C. The influence of the irradiation temperature on the yields of octane, nonane, decane and dodecane was investigated. Relative yields of addition products containing secondary radical increase with temperature. This should be due to secondary hydrogen abstraction from the solvent by primary hexyl and fragment radicals at high temperature.
Solvent Extraction from Molten Salts. XII. Extraction OP Lutetium by Dialkylammonium Thiocyanates
Authors: David‐Auslaender J. , Zangen M. , Kertes A. S. 
Published: September 2010

AbstractThe partition of lutetium(III) between molten sodium‐potassium thiocyanate and chloronaphthalene solutions of dioctyl‐ and didodecylammonium thiocyanate has been determined radiometrically at 150°, 170° and 190°C. The log‐log plots of the distribution ratios versus the concentration of the alkylammonium salt extractants were found to deviate from linearity. The slopes vary between 1 and 2, being steeper for the extractant with the shorter hydrocarbon chain.The data are interpreted in terms of anion exchange equilibria between the monomeric and the aggregated extractant and the anion Lu(SCN)−4
An Investigation of the Submicroanalysis of Metal Surfaces by Electrography and Carbon Filament Atomic Absorption Spectrometry
Authors: Shresta I. L. , West T. S. 
Published: September 2010

AbstractA technique of ultramicro‐atomic absorption spectrometry on a carbon filament following electrographic sampling of the specimen is examined for the analysis of steel surfaces containing Cr, Cu, Mn and Ni in the range down to 0.2%. The matrix effect of the accompanying iron on the anodically dissolved minor elements is studied and simple separation techniques are devised on rapid precipitation of the bulk of the iron or solvent extraction of HFeCl4 to provide extra sensitivity for Cu, Mn or Ni where necessary. Sampling requires only 10 seconds and the entire analysis ± 6 minutes (16 if a separation is necessary). The precision is usually better than 10% but due to variations in sampling or inhomogeneity of the surface a few results may only be within 20% of the expected value. The procedure is recommended as a semi‐quantitative one.
Notiz über Diaddukte aus dem Benzylmercaptan und der Acetylendicarbonsäure Oder Ihrem Dimethylester
Authors: Larsson Erik 
Published: September 2010

AbstractEs wird gezeigt, dass Benzylmercaptan in alkalischem Medium an Acetylendicarbonsäure und ihren Dimethylester unter Bildung von 2,3‐Di (benzylmercapto)‐bernsteinsäuren (oder Methylestern) angelagert wird.
Spectre de Vibration de Complexes a Transfert de Charge de ICN IV.—Perturbation du Spectre du Donneur d'Electrons
Authors: Leeuw J. Ve. , Zeegers‐Huyskens Th. 
Published: September 2010

AbstractThe infrared spectrum and in some cases, the Raman spectrum of some pyridine derivatives complexed with ICN are studied in solvents of low dielectric constants.A number of vibrational frequencies and intensities of some pyridine derivatives (H, 4‐CH3, 2‐CH3, 3, 5‐diCH3, 2, 4, 6‐triCH3) is changed when the molecules are complexed with I‐CN. The a1, (or a) vibrations show the greatest perturbations. The modifications are discussed in terms of the charge transfer model proposed by Mulliken and Ferguson.
Molecular Force Field ‐ Some Octahedral XY6 Type Molecules and Ions
Authors: Thirugnanasambandam P. , Mohan S. 
Published: September 2010

AbstractAll the general quadratic valence force field force constants relating to Some octahedral XY6 type molecules and ions have been evaluated afresh using the Raman and infrared spectral frequencies and certain simplifying considerations from the study of kinetic constants and redundancy constraints by Wilson's F‐G matrix method.
Mobilité du Cation Sodium dans Une Série de Solvants Oxygènes
Authors: Detellier Christian , Laszlo Pierre 
Published: September 2010

AbstractLe temps de corrélation caractéristique de la relaxation quadripolaire du sodium‐23 est obtenu à partir de la largeur de raie. II satisfait à la relation de Debye‐Stokes‐Einstein. Moyennant certaines hypothéses, on peut en déduire un rayon de Stokes de 3, 7 Å pour le cation sodium dans ces solvants.
Isomerization Modes and Longuet‐Higgins Groups
Authors: Fastenakel D. , Brocas J. 
Published: September 2010

AbstractWe analyze the relationship between two fundamental aspects of the study of molecular non‐rigidity: isomerization modes and Longuet‐Higgins groups. We introduce a new formulation of isomerization modes including permutationsinversion. We show how to use this new representation of isomerization modes for constructing Longuet‐Higgins groups, and we illustrate it on an example.
Adsorption of Hydrogen on Supported Metal Catalysts. Microgravimetric Measurements on Supported Rhodium, Platinum and Nickel
Authors: De Vijlder M. , Vanden Kerchove F. 
Published: September 2010

AbstractA micro‐balance was used to compare the adsorption of hydrogen and deuterium on supported metal catalysts, which contained 50% weight percent of Rh, Pt or Ni. Reversible and irreversible adsorption are discerned.The reversible adsorption is the same for hydrogen and deuterium and does not differ much for the three metals. Rhodium adsorbs somewhat more than nickel and platinum.The irreversible adsorption is detected by exchanging the total amount of adsorbed gas by its isotope. For nickel and platinum the irreversible adsorption equals almost the reversible one but for rhodium the irreversible adsorption is by a factor 4 greater.71% of all Rh atoms have bound a hydrogen atom; the percentage is 21% for Pt and 6% for Ni.The dispersion of Rh must be very high, which gives a very high specific surface area of about 300 m2/g rhodium; for the two other metals this area is about 50 m2/g.
The Crystal and Molecular Structure of N,N‐Dimethyl‐Dithiooxamide
Authors: Christensen A. , Geise H. J. , van Der Veken B. J. 
Published: September 2010

AbstractN,N‐dimethyl‐dithiooxamide (DMTO), (CH3)2NCS‐CSNH2 crystallizes in the monoclinic space group P. Cell dimensions at ca. ‐150°C are: a = 9.21 Å, b = 6.76 Å, c = 11.73 Å, β = 104.64 Å. The structure was solved using MULTAN and refined to R = 0.045. The two thiooxamide moieties are in two planes, the dihedral angle between them being 93.1°. The crystal structure confirms predictions of the molecular geometry based on UV, LR, Raman spectra and dipole moment measurements.
Modification d'un spectromètre de masse à géométrie inversée et applications à l'étude de processus collisionnels
Authors: Maquestiau A. , van Haverbeke Y. , De Meyer C. , Flammang R. , Perlaux J. 
Published: September 2010

AbstractThe design of a collision chamber located between the magnetic and electric sectors of a reversed geometry mass spectrometer is described. The analytical and theoretical interests of this arrangement are discussed.
Evidence for the acyclic structure of the stable ϵ‐Fission product ions from α, β‐unsaturated aldehydes, ketones and methylesters
Authors: van De Sande C. C. , De Meyer C. , Maquestiau A. 
Published: September 2010

AbstractCollision Induced Dissociation (CID) spectra indicate that the stable ϵ‐fission product ions (lifetimes > 10−5 sec) produced from α, β‐unsaturated aldehydes and methylketones do not have the widely accepted dihydropyrillium ion structure proposed by McLafferty, but are acyclic as predicted by Meyerson. For the corresponding ions in the mass spectra of α, β‐unsaturated methylesters, the actual structure could not be determined (lack of suitable precursors), although it is shown that they certainly do not have dihydropyrillium ion structure. The stable (M‐H)+ ions from dihydropyrane are acyclic.
Mechanisms of substitution reactions of pentacyanoaquocobaltate (III)
Authors: Viaene L. , D'Olieslager J. , De Jaegere S. 
Published: September 2010

AbstractThe thermal and the photochemical reactions of Co(CN)5H2O2‐ with azide, iodide, hydroazoic acid and hydrocyanic acid are investigated. Data on the photochemical aquation of Co(CN)3−6 as a function of the chemical properties of the medium are also reported. On the basis of these kinetic data a reaction mechanism is proposed which takes into account the important role of the solvent cage surrounding the reacting complex.
Contribution à l'étude theorique de la liaison hydrogène I. Les dimères de l'eau
Authors: Leroy G. , Louterman‐Leloup G. , Ruelle P. 
Published: September 2010

AbstractDans ce travail, nous tentons d'expliquer l'existence et la nature des complexes intermoléculaires par liaison hydrogéne grâce au programme ab initio GAUSSIAN‐70 utilisé avec la base STO‐3G. Nous avons calculé les propriétés du dimère de l'eau. Lea résultats obtenus pour les trois structures possibles de ce système confirment que la plus stable correspond à l'enchaînement linéaire O…H‐0, où la distance intermoléculaire O…H est la plus courte (1.75 Å); l'approche des deux molécules s'effectue selon l'axe passant par l'un des centroïdes de charge de l'oxygène accepteur d'hydrogène avec un transfert de charge vers le système donneur de proton.
Structure de l'ester méthylique de l'acide 2,3‐diméthyl‐2‐phényl‐4 tosyloxybutyrique
Authors: Declercq J. P. , Germain G. , van Meerssche M. , Debaerdemaeker T. 
Published: September 2010

AbstractThe structure of the title compound has been determined in order to observe the relative configuration around the two asymmetric carbon atoms. Crystal data are a=19.148, b=8.446, c=6.180 Å; α=95.39, β=97.49, γ=100.56°; triclinic Pl Z=2[C20H24O5S]. The structure has been solved by Multan and refined by least squares to R=5,2%. Bond lengths and angles are normal.
Properties and reactions of 1,3‐oxathiolans — V. Conformational energy of an axial 2‐t‐butyl group. An attempt to determine epimer equilibria by microcalorimetry
Authors: Pihlaja K. , Keskinen R. , Nikkilä A. 
Published: September 2010

AbstractChemical equilibration of epimeric 2‐t‐butyl‐5‐methyl‐1, 3‐oxathiolans led to ‐ΔHo=4.60±0.05 kJ mol−1 and ‐ΔSo=2.9±0.16 J mol−1K−1 for the trans cis equilibrium. From them and the values of 1H vicinal coupling constants the conformational energy of a ψ‐axial 2‐t‐butyl group was estimated at 8.6±1.3 kJ mol−1. A microcalorimetric determination of the enthalpy difference for the epimer equilibrium resulted in a less accurate value of 4.5±1.0 kJ mol−1 and pointed out some disadvantages connected with the latter method.
Production de Molécules Excitées par Oxydation de Metaux Refractaires
Authors: Forier R. P. , Hiernaut J. P. , van Cakenberghe J. 
Published: September 2010

AbstractLa réaction d'oxydation de métaux réfractaires à haute température (1000‐2500° C) et basse pression (10−2‐ 10 torr) produit des oxydes volatils. Ceux‐ci peuvent se condenser sur une cible qui est la cathode d'une lentille électrostatique suivie d'un multiplicateur d'électrons secondaires. Durant la condensation, il apparait une émission électronique. L'intensité de cette émission est une fonction de la température du filament et de la pression d'oxygène dans le réacteur.
1H‐NMR study of 2,3,4,6,3′,4′‐hexa‐o‐acetyl‐1′,6′‐diacetamido‐1′,6′‐dideoxy sucrose at 300 MHZ
Authors: De Bruyn André , Anteunis Marc , Suami Tetsuo 
Published: September 2010

AbstractThe1H‐NMR parameters of the title compound (1) have been obtained for D2O and benzene/acetone solutions. The conformations of the rings and around the C(5′)‐C(6′) fragment of the β‐D‐fructofuranosyl part are discussed. The furanose moiety behaves differently from that in sucrose octaacetate itself.
Cyclopentanones. XVII: Prostaglandin synthesis involving the lithium‐liquid ammonia reduction of 3‐alkyl‐4‐hydroxy‐2‐(1′‐octynyl)‐2‐cyclopentenones
Authors: De Clercq P. , De Smet M. , Legein K. , Vanhulle F. , Vandewalle M. 
Published: September 2010

AbstractThe present paper describes the lithium‐liquid ammonia reduction of 3‐alkyl‐4‐hydroxy‐2‐(1′‐octynyl)‐2‐cyclopentenones; depending on the nature of the 3‐alkyl side chain prostaglandins of the F1‐series or primary prostaglandins of the 2‐series are synthesised.
Interaction of 1‐anilinonaphthalene‐8‐sulphonate (ANS) with egg‐white lysozyme and bovine α‐lactalbumin. Fluorescence study
Authors: Versee V. , Barel A. O. 
Published: September 2010

AbstractFluorescence titrations indicate that both proteins bind approximately one mol of ANS per mol of protein. The dissociation constant of the protein‐dye complex was 0.3 mM for lysozyme and 0.2 mM for α‐lactalbumin, indicating a moderate binding of the dye to either protein.The results support the view that the enhancement of fluorescence of this dye in presence of both proteins is primarly caused by an environment of decreased polarity.The fluorescence of the lysozyme‐ANS and α‐lactalbumin‐ANS complexes was not diminished by the presence of salts (KCl and K2SO4). From these last results it is suggested that ionic interactions do not play a significant role in binding.Considering the fluorescence properties of the α‐lactalbumin‐dye complex, it was found that the binding site on α‐lactalbumin was more hydrophobic than that on lysozyme.
N‐Acylamino acids and peptides V Improved synthesis of N‐Ferulylglycyl‐L‐Phenylalanine
Authors: van Rompaey L. , De Pooter H. , van Sumere C. F. 
Published: September 2010

AbstractAs a result of difficulties with the synthesis of pure O‐(m)ethoxycarbonylferulyl chloride, N‐ferulylglycyl‐L‐phenylalanine (XVI) was previously prepared by a mixed anhydride method. However, due to the fact that analogous N‐acyl‐dipeptides were easily obtained by the acid chloride method, the synthesis of XVI was reinvestigated.After abortive tries to use the condensation of O‐p. bromophenacyl‐ferulyl chloride with N‐glycyl‐L‐phenylalanine t‐butyl ester, a method for the reproducible synthesis of pure 0‐ethoxycarbonylferulyl chloride was developed. Reaction of the latter substance with N‐glycyl‐L‐phenylalanine t‐butyl ester, followed by removal of the protecting groups from the condensation products, afforded N‐ferulylglycyl‐L‐phenylalanine in 51% yield. This last recovery compares favourably with the earlier published yield of 30%.
Studies of rhodium‐103 nuclear shielding by heteronuclear magnetic double resonance
Authors: McFarlane H. C. E. , McFarlane W. , Wood R. J. 
Published: September 2010

AbstractRhodium‐103 chemical shifts have been measured by 1H‐{103Rh} heteronuclear double resonance in a series of octahedral rhodium (III) complexes with phosphine/chalcogen ligands, including some mixed species. The shifts are significantly temperature dependent, and are also sensitive to fine details of molecular conformation and configuration.
Optically active transition metal complexes, XLIV. The nature of the chiral intermediates involved in the racemization and ligand exchange reactions of optically active manganese compounds
Authors: Brunner H. , Steger W. 
Published: September 2010

AbstractThe syntheses and spectra of new compounds of the type (RC5H4)Mn(NO)(COR')‐P(C6H5)3, (RC5H4)Mn(NO)(COR')CO, and (RC5H4)Mn(NO)(CO)R' with R=H, CH3; R=C6H5, CH3 are described.The reaction of P(C6H5)3 with the σ‐methyl and σ‐phenyl complexes (RC5H4)‐Mn(NO)(CO)R' with formation of (RC5H4)Mn(NO)(COR')P(C6H5)3 is so slow that σ‐alkyl and σ‐aryl compounds cannot be the chiral intermediates involved in the racemization and ligand exchange reactions of (+)‐ and (‐)‐(RC5H4)‐Mn(NO)(COR')P(C6H5)3.
Calculs Extended Hückel sur Molécules et Réactions Organiques
Authors: Simonetta M. , Gavezzotti A. 
Published: September 2010

AbstractDans cette mémoire, les caractéristiques principales de la méthode Extended Hückel sont brièvement exposées. Des exemples d'application de cette méthode à l'étude de problèmes de structure et réactivité sont examinés et discutés.
Mass Spectrometry of o‐Ethyl‐o‐Aryl‐Phenylphosphonothioates
Authors: Steurbaut W. , Dejonckheere W. , De Kimpe N. , Schreyen L. 
Published: September 2010

AbstractThe mass spectra of O‐ethyl‐O‐aryl‐phenylphosphonothioates are investigated and discussed. Besides direct classical fragmentation (α‐fissions), migration of both an aryl group and a double bond occurs between sulphur and oxygen prior to fragmentation, resulting in some unexpected m/e valvues. The most abundant ion was m/e 157, which could be reasonably explained in terms of loss of a phenoxy moiety followed by ethylene expulsion.
The Dielectric Behaviour of the Propyleneglycol‐Water System from 15 to50°C
Authors: Verbeeck R. M. H. , Thun H. P. , Verbeek F. 
Published: September 2010

AbstractDielectric constants at 1.8 MHz of the propyleneglycol‐water system are determined from 15 to 50°C at 5° intervals. The dielectric behaviour of the system is discussed in terms of a deviation from a linear function of the volume fraction of the components. Comparison with the monohydric alcohols and ethyleneglycol reveals the importance of the apolar/polar group ratio in the intermolecular interactions.
Hétérocycles Organiques De L'Arsenic; VI Synthèse, Structure Et Stéréochimie D'Arsatranes Hexacoordinés
Authors: Maroni P. , Holeman M. , Wolf J. G. 
Published: September 2010

AbstractFrom tetracoordinated “arsatranes” and orthochinons new arsenic derivatives were synthesised according a “Kukhtin‐Ramirez” reaction. PMR and X‐ray studies showed in these compounds the same N → As bond as in the starting products, thus revealing the existance of a new series of hexacoordinated “arsatranes”.
Une Synthèse Aisée De Diméthyl‐6",6" Pyrannoisoflavones Angulaires
Authors: Vilain C. , Jadot J. 
Published: September 2010

Abstract3‐hydroxyisovaleraldehyde dimethyl acetal(I) is condensed in the presence of pyridine with 2,4‐dihydroxy phenyl benzyl ketones (IIa, b, c, d) to give 2,2‐dimethyl‐6‐phenylacetyl‐5‐hydroxychromenes (IIIa, b, c, d); these intermediates are directly converted into the corresponding angular 6", 6"‐dimethylpyranoisoflavones (IVa, b, c, d) by condensation with ethylorthoformate in the presence of pyridine and piperidine. Compounds IV b and IV d are respectively identical with the natural products Calopogonium Isoflavone A and B wich we have described earlier.