bluuebunny/crossref_metadata_2025_split huggingface dataset:
Un Exemple de L'Utilisation des Complexes Paramagnétiques Dans les Études Conformationnelles
Authors: Grandjean J. 
Published: September 2010

AbstractWe have deduced the most probable conformation for 4‐cycloheptene carbinol‐8d2 in deuteriochloroform solution from coupling constants and paramagnetic shifts induced by Eu(DPM)3.
Structure Cristalline de Dérivés D'Acides Aminés VI. Le Composé HI.2 Glycine
Authors: Piret P. , Meunier‐Piret J. , Verbist J. , Meerssche M. Van 
Published: September 2010

AbstractDiglycine hydro‐iodide is monoclinic, space group C2 with unit cell parameters a = 18.592, b = 5.160, c = 20.372 Å. β = 110.64°; Z = 8. The crystal structure has been determined using three‐dimensional diffractometer data.The asymmetric part of the unit‐cell contains two independent iodine ions, two glycinium ions NH3 +CH2COOH and two zwitter‐ions NH3 +CH2COO−. The different ions are connected by hydrogen bonds N‐H+… I−, N‐H+… O− and O‐H… O−.
The Force Constants of Phosphorus Compounds I. Discussion of the Computational Method
Authors: van Der Veken B. , Desseyn H. , Herman M. 
Published: September 2010

AbstractIn this first part we tested the convergence of the method of Becher and Mattes on an example in our field of interest, and localised the results in the space of all the real solutions of the inverse vibrational eigenvalue problem. This method was also compared with the classical least squares refinment procedure.
Extension of LCAO Density Matrix Method for Solids and Polymers
Authors: Andre J. M. , Delhalle J. , Leroy G. 
Published: September 2010

AbstractA direct solution of SCF‐LCAO wave functions for solids through an extension of Mc Weeny's steepest descent method is presented. This procedure completely avoids diagonalization of secular systems in many k‐points of the first Brillouin zone and is of practical interest for numerical applications.
Réduction de L'acide Sélénieux par le Cuivre et par Électrolyse en Présence de Cu (II)
Authors: Ladriere J. 
Published: September 2010

AbstractFrom solutions containing CuSO4 and H2SeO3, acidified with H2SO4, several Cu‐selenides are obtained using Pt as a cathode: CuSe, Cu3Se2 and Cu2‐XSe(X=O,2). The Cu‐contents of the deposit increases as a function of the current density. The reduction by metallic copper also produces Cu2‐XSe. For both cases, the reaction rate is controlled by a mass transfer process in liquid phase.
Vibrational Spectra of Some Charge‐Transfer Complexes of Anilines
Authors: Lichtfus G. , Zeegers‐Huyskens Th. 
Published: September 2010

AbstractThe vibrational spectrum of some charge‐transfer complexes of aniline‐iodine and aniline‐1, 3 dinitrobenzene is examined. It is shown that the antisymmetric and symmetric v vibrations are shifted to lower wavenumbers by complexation by 2 iodine and to a lesser extent by dinitrobenzene.The HNH angle, the force constant of the N‐H bond and the percentage of s‐character of the latter decrease with complexation. The variations are however less than for the free anilines; this fact can be explained in terms of a competition between an intermolecular and intramolecular charge transfer.The vibrational spectrum of the aniline‐iodine complex is studied in several solvents in the region 3500 ‐ 600 cm−1. Several vibrational modes are perturbed in intensity. It is shown that the vibrations that are mainly perturbed are those producing a variation of the ionisation energy of the electron donor or a variation of the overlap integral between the donor and the acceptor.
Interaction between Organometallic and Aromatic Molecules in their Electronic Ground State Study of the Singlet to Triplet Absorption Spectrum of 1‐Chloronaphthalene in the Presence of Dimethylmercury
Authors: Donckt E. Vander , Vogels C. 
Published: September 2010

AbstractThe interaction between 1‐chloronaphthalene and dimethylmercury in their electronic ground state has been examined by visible absorption spectroscopy. In the presence of the organometallic molecule, the first singlet to triplet absorption band of 1‐chloronaphthalene is strongly enhanced. The variations of the optical density at 427.5 nm are used to determine the stoichiometry and the concentration of a possible ground state complex between the two species as a function of the mole fraction of dimethylmercury.From the consideration of the experimental thermodynamic parameters for the assumed equilibrium:it appears that there is no strong case for such a complex. These results strengthen our previous interpretation of aromatics' fluorescence quenching by dimethylmercury.
The Determination of Nitrate in Mineral Waters by Potentiometry and U.V. Spectrophotometry
Authors: Mertens J. , Hassart D. L. 
Published: September 2010

AbstractProcedures for the determination of nitrate in mineral water in the 0,5 ‐ 5 p.p.m. concentration range with the nitrate selective electrode and U.V. spectrophotometry are compared with a classical colorimetric procedure.Because the use of a calomel electrode and Hg‐Hg2SO4 electrode as reference electrode caused short‐time fluctuations, the potentiometric determination was carried out using a fluoride selective electrode as reference electrode after addition of a fluoride spike to the solution.The U.V. method proved to be rapid, precise and accurate.The potentiometric method was also very rapid and although it gave acceptable results in five cases out of six it is inferior to the U.V. spectrophotometry in the other aspects.
N‐Acylamino Acids and Peptides II. The Synthesis of N‐Feruloylglycyl‐[l and DL]‐Phenylalanine
Authors: De Pooter H. , Ali Haider , van Sumere C. P. 
Published: September 2010

AbstractN‐Feruloylglycylphenylalanine (IX) was obtained by alkaline hydrolysis of N‐feruloylglycyl‐L‐phenylalanine methyl ester (III) or N‐(O‐methoxycarbonylferuloyl)‐glycyl‐L‐phenylalanine methyl ester (VIII). III was prepared from N‐feruloylglycine (I) and L‐phenylalanine methyl ester (II), while VIII was synthesized from protected ferulic acid (VII) and N‐glycyl‐L‐phenylalanine methyl ester (VI). Dubious optical purity of the final compound (IX) led to the use of N‐glycyl‐L‐phenylalanine t.butyl ester (XII) as starting material for the condensation with O‐methoxycarbonylferulic acid (VII), resulting in the isolation of optically pure N‐feruloylglycyl‐L‐phenylalanine (XIV). The latter procedure, when applied to N‐glycyl‐DL‐phenylalanine t.butyl ester, gave racemic N‐feruloylglycyl‐phenylalanine. The peptide or amide bonds were generally introduced by the mixed anhydride method as proposed by Birr et al [7], i.e. using anisoyl chloride as the anhydride‐forming reagent. XIV proved to be identic with a feruloyl‐containing peptide isolated from barley protein hydrolysate [2].
Organometallic compounds. Part 36. Synthesis and mass spectra of racemic tetraalkyltins
Authors: Gielen M. , De Poorter B. , Sciot M. T. , Topart J. 
Published: September 2010

AbstractThe synthesis of racemic tetraalkyltin compounds is described, starting from tributyltin chloride and using alternating Grignard syntheses and bromodemetallations in alcohols.The mass spectra of the obtained tetra‐ and triorganotin derivatives are given as analytical evidence for their obtainment.
Synthesis and Properties of ω‐Substituted Alkyltin Derivatives and of Copolymerizable ω‐Alkenyltin Compounds
Authors: Gielen M. , De Poorter B. , Liberton R. , Paelinck M. T. 
Published: September 2010

AbstractThis paper describes the synthesis and spectroscopic identification of ω‐undecenyl‐, ω‐butenyl‐ and ω‐pentenyltriphenyltin compounds. Those of ω‐phenyl‐ and ω‐phenoxyalkyltin derivatives are also given.
Alternative Syntheses of 4‐Ethoxycarbonylchroman‐3‐One
Authors: Verhé R. , Schamp N. 
Published: September 2010

AbstractThree syntheses of 4‐ethoxycarbonylchroman‐3‐one, a key intermediate in the synthesis of dehydrorotenoids, were described. The Dieckmann condensation of ethyl (2‐ethoxycarbonylmethoxyphenyl) acetate gave only 4‐ethoxycarbonylchroman‐3‐one in high yield, and not a mixture of the 2‐ and 4‐ethoxycarbonyl derivatives as previously reported.
Theoretical Rate Constants for the Formation and Decomposition of Chlorinated Ethyl Radicals
Authors: Skinner Gordon B. , Rabinovitch B. S. 
Published: September 2010

AbstractAbsolute Rate Theory calculations of the rate constants for addition of Cl atoms to ethylene and to the variously chlorinated ethylenes have been made, together with Marcus‐Rice theory calculations of the decomposition rate constants for loss of CI atoms from the resulting energized chloroethyl radicals. Agreement with literature data is almost within experimental error, except for dissociation of C2Cl5; it is suggested that in this case the reported rate may be low. The calculational models for the radicals were ethane‐like, with hindered rotation about the C‐C bond. Ethylene‐like activated complexes have been assumed; the entering (or leaving) CI atom is very loosely bonded to one of the C atoms of the ethylene; alternatively, a Gorin complex, in which the CI is associated with the entire ethylene molecule which retains its original overall rotations, was also considered.
N. M. R. Experiments on acetals. XXXVIII. The conformational equilibrium in trans‐4, 5, 5‐trimethyl‐6‐alkyl‐1, 3‐dioxanes
Authors: Tavernier D. , Anteunis M. 
Published: September 2010

AbstractThe chair‐chair equilibrium in trans‐4, 5, 5‐triMe‐6‐alkyl‐1, 3‐dioxanes (alkyl = Et, n.Pr, i.Bu, neoPe, i.Pr and Ø) has been studied by the slow exchange NMR shift method. The conformer with equatorial alkylgroup is the more stable one, free energy differences δG°186 (cal/mole) being: 70 (Et), 84 (n.Pr), 10 (i.Bu), 506 (neoPe), 674 (i.Pr) and > 1 000 (ø).
Décomposition thermique des diphényl‐3, 4 carbomethoxy‐3 méthyl‐5 pyrazolines‐1
Authors: Deleux J. P. , Leroy G. , Sana M. , Weiler J. 
Published: September 2010

AbstractLa thermolyse des diphényl‐3/4 carbométhoxy‐3 méthyl‐5 pyrazolines‐1 a été étudiée par volumétrie et par analyse thermique différentielle. Le bilan détaillé de ces réactions confirme l'influence de la configuration des pyrazolines sur la nature des produits de décomposition. Le rôle important joué par les facteurs stériques dans la nature des oléfines formées est également mis en évidence.
The Synthesis Of 3‐Acetyl‐5‐Alkylpyridines
Authors: Esmans E. L. , Alderweireldt F. C. 
Published: September 2010

AbstractThe synthesis of 3‐acetyl‐5‐methyl‐ ; 3‐acetyl‐5‐ethyl‐ ; 3‐acetyl‐5‐propyl‐ and 3‐acetyl‐5‐isopropylpyridine was accomplished by the condensation of the corresponding acroleïne derivatives and 1‐amino‐1‐buten‐3‐one.
Étude Ab Initio Des Dérivés Fluorés De L'éthylène Et De Leurs Anions
Authors: Leloup G. , Leroy G. 
Published: September 2010

AbstractLos dérives mono‐, di‐ et trifluorés de l'éthylène ainsi que les anions correspondants sont étudiés par la methode de ROOTHAAN dans une base de fonctions gaussiennes contractées. Une analyse comparative des propriétés électroniques met en évidence l'influence de la substitution de l'hydrogene par le fluor. Une étude partielle du chemin de réaction de la déshydrofluoration permet de prévoir qualitativement l'acidité et la réactivité de ces composés.
Relative Solvation of Silver and Hydrogen Ions in Water ‐ Tert. Butylalcohol Mixtures: Mobilities and Free Enthalpies of Transfer
Authors: Smits R. , Massart D. L. , Juillard J. , Morel J. P. 
Published: September 2010

AbstractLimiting ionic conductivities of silver, nitrate and hydrogen ions, and transfer free enthalpy changes for Ag+, H+ ion couples in water ‐ tert. butanol mixtures are reported. The curves that represent the ratio of the Walden products (or the limiting ionic conductivities) on the one hand and the difference of the transfer free enthalpies on the other in function of the solvent composition are also given for the Ag+/H+ pair. In both curves, breaks are observed at 0.05 mole fraction of tert. butanol. This phenomenon is discussed in terms of relative solvation and structuration of the solvent. Comparison is made with dioxane ‐ water systems.
Influence de la Température sur la Conductivité Électrique du Thiocyanate de Potassium Fondu
Authors: Dulieu P. , Class P. 
Published: September 2010

AbstractLa conductivité spécifique et la masse volumique du thiocyanate de potassium fondu ont été déterminées dans un domaine de température s'étendant de 448°K à 553°K.La dépendance de la conductance équivalente vis‐a‐vis de la température est décrite de manière satisfaisante par l'expression: 1 = B1 exp[‐K1/ (T–To)] dans laquelle B et K sont des eonstantes. To est une température ds référence qui, dans le cas du système étudié, vaut 203 °K.
Manganese Ions as Paramagnetic Probes in Magnesium Oxide. I. Surface Reactivity
Authors: Derouane E. G. , Indovina V. 
Published: September 2010

AbstractThe reversibility of the Mn2+ → Mn3+ → Mn4+ reaction, in MgO samples containing initially near 1 at.‐ppm of bulk Mn2+ ions is examined as a function of evacuation pretreatments at nearly 1200 K eventually followed by adsorption of H2, D2, or H2O vapor at 298 K. Two bulk e. s. r. signals are observed which correspond respectively to Mn2+ and Mn4+ ions.The Mn lines are strongly affected by adsorption at room temperature or 77 K of various gases and vapors.Mn3+ ions, not detected by e. s. r., must also be present to account for the relative intensity changes of the Mn2+ and Mn4+ species as detected by e. s. r. Electronic conduction paths, must be available between the surface and the bulk.
Manganese Ions as Paramagnetic Probes in Magnesium Oxide. II. Crystal Growth and Ionic Diffusion
Authors: Derouane E. G. , Thelen J. , Indovina V. 
Published: September 2010

AbstractThe Mn2+ e. s. r. signal in MgO samples, containing 1‐2000 at ‐ ppm of manganese, is used as a paramagnetic probe to monitor the behavior of fresh MgO powders following thermal activation at 800 K ‐ 1200 K in vacuum or in air.Two distinct Mn2+ signals are generally observed after evacuation and they correspond respectively to substitutional Mn2+ ions and clusters of Mn2+ ions near the surface.From the spectral intensity and the zero‐field splitting term, D, informations have been obtained on the particle growth in metastable fresh MgO powders thermally treated in the range 800 ‐ 1200 K, and on the progressive diffusion of surface Mn2+ ions into the bulk of MgO. The D‐term decrease with lower manganese content or higher temperature thermal treatment is interpreted as a diffusion of Mn2+ ions towards cationic sites with more accurate cubic symmetry, i.e., more distant from the surface. After activation in air at 1300 K, all the apparent Mn2+ ions are found to be in perfectly octahedral sites in the bulk of MgO. A mechanism by which manganese ions are incorporated at substitutional sites in the lattice is discussed.
Les Nitrates Basiques Mixtes de Zinc et de Cobalt
Authors: Mannoorettonnil M. , Glibert J. 
Published: September 2010

AbstractThe basic zinc and cobalt nitrates, obtained at 20°C by addition of soda to Zn(NO3)2 or Co(N03)2 solutions (0, 2 M M++/1), have the respective compositions Zn5(OH)8(NO3)2.2 H2O and 4 Co(OH)2.Co1, 25 (OH)1.O (NO3)1, 5 H2O. At 75°C, ZnO and β‐Co(OH)2 are formed.In mixed (Zn, Co)‐solutions, at 20°C and for a reaction time of about 1 hour, the solid solution Zn5‐x‐ Co (OH)8 (NO3)2.2 H2O (1) has only a small existence range and transforms progressively into the mixed basic nitrate 4 Zn1‐x Cox (OH)2. Zn1‐y Co (OH)(NO3) (II)(max. 67% at. Co). For higher percentages, the basic cobalt nitrate phase appears. By aging at 20°C, the solid solution (I) is stabilized up to 48% at. Co, whereas at 75°C, there is formation of Zn1‐x CoxO (max.I% at. Co). In both cases, the mixed basic nitrate (II) ranges approximatively from 50 to 75% at. Co. For cobalt‐rich solutions appears a zone of demixtion between β‐Co(OH)2 and a new mixed basic (Co, Zn)‐nitrate (1, 7 < OH− /Me++ < 1, 8).
Quenching of Triplet 1,3‐Pentadienes by Their Ground State
Authors: Bigwood M. , Boué S. 
Published: September 2010

AbstractSensitization of neat cis or trans 1,3‐pentadienes by triplet benzophenone leads only to isomerization and dimerization. The quantum yields measured for these processes as well as the photostationary composition are strikingly different from the figures obtained in dilute solution and indicate that an interaction between the triplet and a ground state molecule can be an efficient path for triplet decay. A kinetic scheme is proposed which accounts for all of the experimental facts and suggests that an excimer is involved.
Chemical Ecology of Arthropods. VIII. Synthesis and Absolute Configuration of Adaline
Authors: Tursch B. , Chome C. , Braemkan J. C. , Daloze D. 
Published: September 2010

AbstractNatural 1‐Adaline is shown by ORD to have the R‐configuration at carbon atom 1. dl‐Adaline has been synthetized in four steps, starting from 1‐octen‐3‐ol.
Effets D'Additifs Sur Les Bendements Des Hydrocahbures legees Dans La Radiolyse Du Méthyl‐3‐Pentane Vitreux A 77°k
Authors: De Hollain G. , Tilquin B. , Claes P. 
Published: September 2010

AbstractMethyl‐3‐pentane was irradiated with 60Co γ rays in the glassy state at 77 K with carbon tetrachloride and pentene‐2 as solutes. The yields of the organic gases have been investigated as a function of the solute concentration (0 to 5 mole %). A pentene‐2 concentration of 0,8 mole % reduces the yields of the organic gases by 40 % while CCl4 at a concentration of 2,5 mole % reduces these yields by 70 %.The diminution of the yields is explained by a scavenging of the positive charge in the case of pentene‐2; carbon tetrachloride exhibits a more complex behaviour; it acts as an electron scavenger by dissociative electron attachment and also probably by absorbing the electronic excitation energy.
Essais de Chloration Dirigée XIX. Photochloration Comparée D'Alkyltrichlorosilanes et de Trichloro‐1,1,1 Alcanes. 2. Photochloration Consécutive de L'Éthyltrichlorosilane et du Trichloro‐1,1,1 Propane
Authors: Burton Th. , Bruylants A. 
Published: September 2010

AbstractConsecutive photochlorination of 1,1,1 trichloropropane and ethyltrichlorosilane was studied along with the classical method in order to isolate relative reactivities and so evaluate the substrate influence on the mesenteric effect of chlorine. It is confirmed that the intensity of the mesomeric effect depends on the electrocaptor power of the other substituents on the considered molecule : “The nearer chlorine to an electrocaptor group, the higher its mesomeric effect”. The study of molecules as XCl3‐CH2‐C3 (X=C or Si) revealed that the α hydrogen reactivities are identical to or lesser than α reactivities in XCl3‐CHCl‐CH3; on the contrary, β hydrogen reactivities in molecules such as XCl3‐CH2‐CH3 are much higher than β reactivities in XCl3‐CH2‐CH2Cl: inductive effect of chlorine can not be excelled by its mesomeric effect; the group opposed toβ chlorine substituent is less electrocaptor (Cl3X‐CH2‐CH2) than in α substitution (Cl3X‐CH‐CH3). All relative reactivities are discussed in that way.
Fragmentation, par Spectrométrie de Masse, D'Alcools β, γ‐Acétyléniques α, β‐Éthyléniques
Authors: Kossanyi J. , Chuche J. , Manisse N. , Vandewalle M. 
Published: September 2010

AbstractThe mass spectra of β, γ‐acetylenic‐α, β‐allylic alcohols are discussed. The main fragmentation is directed by the allylic position of the alcohol function. Deuterium labeling and the presence of a methyl substituent in different positions suggest that some degradations occur through a cyclic structure of the molecular ion. The Cope rearrangement, a normal thermal reaction of the compounds, is not observed under the mass spectrometric conditions used.
Studies in Organic Mass Spectrometry. XIV: Investigation of Electron Impact Induced Isomerisation of 2′‐Hydroxy‐Acrylophenones and Chroman–4–ones
Authors: van De Sande C. , Vandewalle M. 
Published: September 2010

AbstractThe mass spectral behaviour of nine pairs of isomeric 2′‐hydroxy‐acrylophenones and chroman‐4‐ones is outlined. Metastable ion analysis has been applied to investigate isomerisation prior to fragmentation. A comparison is made between behaviour under electron impact and in solution chemistry; aryl substituted isomers behave similarly under both conditions while alkyl substituted homologs show an one‐way isomerisation in opposite directions.
Synthesis of Some New 7‐Mono and 7, 7‐Disubstituted Norbornanes and ‐Norbornenes. H‐NMR Spectrum of 2‐Methyl‐Spiro (1, 3‐Dioxane‐5,7′‐Norborn‐2‐Ene
Authors: Bernaert E. , Anteunis M. , De Waele R. 
Published: September 2010

AbstractStarting from 7‐norbornanone and norborn‐2‐en‐7‐one a reaction sequence for the synthesis of spiro (1, 3‐dioxane‐5, 7′‐norbornane) and 2‐methyl‐spiro (1, 3‐dioxane‐5, 7°‐norborn‐2°‐ene) is described.1H‐NMR pecularities of some Intermediate derivatives are discussed, especially those of the title compound, where a large number of long‐range couplings have been observed. Axial‐axial 4‐6 coupling in the dioxane moiety was found to be unexistent, in contrast to some other cases, but equatorial‐equatorial 4‐6 coupling is one of the largest ever encountered 03.25 Hz).
Preliminary study of the E. S. R signals in unsupported cobalt sulfide‐molybdenum sulfide mixed masses.
Authors: Hagenbach G. , Menguy F. , Delmon B. 
Published: September 2010

AbstractUnsupported cobalt sulfide‐molybdenum sulfide mixed catalysts exhibit two distinct E. S. R. signals. A first signal (g= 2.007, ΔH=90G) is detected at room temperature. It is attributed to Mo5+. The Mo5+ content decreases with increasing Co content, from a value Mo5+/Mo of 0.01% with pure molybdenum sulfide, to negligible values for Co/(Co + No) > 0.5. A second, low temperature, signal gradually appears between 143 and 133°K (g = 2.17, ΔH = 300‐600G). It is apparently related to some cobalt containing species. This signal, practically negligible for each monometallic sulfide, exhibits a sharp maximum for a value Co(Co + Mo) of 0.2, which corresponds to maximal intrinsic (per m2) catalytic activities of the samples in the hydrogenolysis of thiophene, hydrogenation of cyclohexene and isomerization of cyclohexane.
On‐stream determination of ammonia in boiler feed‐water with an ammonium ion selective electrode and an ammonia probe.
Authors: Mertens John , Winkel Pierre Van Den , Massart D. L. 
Published: September 2010

AbstractThe development of methods for on‐stream determination of ammonia in boiler feed‐water by means of an ammonia probe and an ammonium selective membrane electrode is described. A pilot‐plant simulating a boiler feed‐water circuit was used. The two electrode systems were connected in parallel to the circuit so that their behaviour could be checked simultaneously. The accuracy and the reproducibility were very satisfactory. The response of the two electrode systems is fast enough for on‐stream measurement. They are practically free from interferences which could be present in boiler feed‐water, except the probe which is subject to interferences from volatile amines.
Studies in organic mass spectrometry. XVII The fragmentation of methyl enol ethers of 1,3‐cyclohexanediones and 1,3‐cyclopentanediones
Authors: Cant E. , Maenhaut‐Claeys M. , Francque M. , Vandewalle M. 
Published: September 2010

AbstractThe influence of alkyl substituents on the mass spectral behaviour of methyl enol ethers of 1,3‐cyclohexanediones and 1,3‐cyclopentanediones is studied. Six membered ring compounds behave quite straithforwardly and in accordance with the fragmentation suggested for 1,3‐cyclohexanediones in the enol form. Some fragmentations are supported by deuterium labelling.In the case of enol ethers of 1,3‐cyclopentanediones the 4‐ or 5‐substituted isomers display identical spectra. This isomerisation is studied by metastable transitions, low energy spectra and deuterium labelling; a possible mechanism is advanced.