bluuebunny/crossref_metadata_2025 huggingface dataset:
The Vibrational Spectrum of Trimethylphosphine Oxide
Authors: Green J. H. S. , Lauwers H. A.
Published: September 2010

The infrared (3650‐50cm−1) and Raman spectra of trimethylphosphine oxide in the solid and solution states are reported and interpreted, and all the active fundamentals, with one exception, are assigned.
The Complexes of Ni(II) and Pd(II) with Monothio‐Oxamide and Some of its Derivatives
Authors: van de Cappelle G. L. , Herman M. A.
Published: September 2010

The Ni(II) and Pd(II) complexes of monothio‐oxamide and four of its derivatives are studied. The composition and structure of these complexes are given for various media. The stability constants of the Ni(II) complexes are determined by potentiometric methods in water and in various mixtures of water and dioxane. Those of the Pd(II) complexes are obtained by spectrophotometric measurements in 2N HClO4 medium. Several methods for the calculation of the stability constants are used and compared. The computed values agree very well.
Thermodynamics of the Proton Ionisation of the p‐Anisidinium Ion in Aqueous Sodium Chloride Solutions: A Mass Transfer Study
Authors: Aboul‐Seoud A. , Mansour I. A. S.
Published: September 2010

The distribution method was modified in several directions: petroleum ether was used as extracting solvent; the ratio of the volumes of the organic and aqueous phases was varied so as to keep the weight of the amine in the aqueous phase approximately equal to that in the organic phase; and the amine in the organic phase was determined by means of ultraviolet spectrophotometry. The distribution of the amine (p‐anisidine) between the 2 phases was studied at different temperatures and different ionic strengths. The salting coefficient was determined at the different temperatures. The thermodynamic proton ionisation constant of the p‐anisidinium ion was found to be 6.10×10−6, 6.70×10−6, 10.00×10−6, and 12.90° 10−6 at 10, 20, 30 and 40°C, respectively. The heat of proton ionisation was found to be 4.45 kcal. ΔG and ΔS were also determined.
The Clausius‐Clapeyron Equation in Monolayers: I. Thermodynamic Treatment
Authors: Joos P.
Published: September 2010

Starting from the Gibbs‐Duhem equations the heats of formation from the collapse and, the equilibrium spreading pressure in monolayers are obtained. Also surface azeotropes are considered. The heat of phase transition of the first order is examined. It results that the Gibbs‐Duhem equation for the monolayer can be written by fixing the dividing surface or relative invariant quantities can be used.
The Clausius‐Clapeyron Equation in Monolayers: II. Some Experimental Evidence
Authors: Joos P.
Published: September 2010

The phase diagrams (transition pressures and collapse pressures as a fraction of temperatures) were obtained for myristic acid, methylpalmitate, ethylpalmitate and methylmyristate. Transitions in the monolayer and in the collapsed phase are indicated by kinks in the collapse pressure/temperature curves. The heats of transition were calculated and also the heats of melting for methylpalmitate and ethylpalmitate. The values obtained in this way are in agreement with those obtained by calorimetry.
Indole Alkaloids XXV: The Oxidation of Voachalotine with Potassium Dichromate
Authors: Braekman J‐C. , Kaisin M. , Pecher J.
Published: September 2010

The study of the chromic oxidation of voachalotine (I) shows that the reaction proceeds in two steps. In the first step, (I) is transformed into dehydrovoachalotine (2), voachalotine oxindole (3) and 6‐oxovoachalotine (5). In the second step which occurs in the presence of acetic acid, (2) is further oxidized to dehydrovoachalotine pseudoindoxyl (7), dehydropolyneuridine pseudoindoxyl (6) and dehydrovoachalotine oxindole (8). The structure of each of these compounds is discussed and a scheme for their formation is proposed.

The oxidation of voachalotine N‐oxide without added acetic acid gives the same reaction mixture containing (2), (3) and (5).

Finally the oxidation of dehydroxymethylvoachalotine (12) in dilute acetic acid gives 6‐oxodehydroxymethylvoachalotine (13). dehydroxymethylpolyneuridine oxindole (14) and dehydroxymethylvoachalotine oxindole (15). No pseudoindoxyl derivatives could be detected in this case.
Étude par Spectrométrie Infrarouge de la Complexation Entre les Phénols Substitués et les Pyridines Substituées
Authors: Clotman D. , Muller J. P. , Zeegers‐Huyskens Th.
Published: September 2010

Complexation constants of hydrogen bonded complexes between substituted phenols and substituted pyridines were determined by infrared spectroscopic measurements in carbon tetrachloride at 25°C.

It was previously shown that for monosubstituted complexes the complexation constant Kab obied the relation log Kab = log Ko + ρσ where σ is the Hammett substitution constant.

When both the proton donor and the proton acceptor are substituted, it is shown in the present work that the logarithm of the complexation constant can be expressed by the equation:

where Koo, refers to the unsubstituted complexe phenol‐pyridine: ρ is the ρa value when σb is zero and ρ0b the ρb value when σa is zero.

The product Bσaσb is an interaction term where B = −0,57. This relation shows that an increasing acidity of phenol enhances the substitution effects on the pyridine. This interaction term is discussed in terms of dipolar and polarisation effects. A similar equation was previously found for the phenol‐aniline disubstituted complexes. In the present case, the ρ and ρ values are greater owing to the stronger basicity of pyridine, and to the smaller O…N distance. The B constant however is greater with the aniline (− 1,70) than with the pyridine complexes. This fact is discussed in terms of the variation of hybridization of the nitrogen atom in the complexes, which in the case of aniline, can be deduced from HNH angle measurements.
Cyclopentanones V. Synthesis of alkylsubstituted 1,3‐cyclopentenediones and 1,3‐cyclopentanediones
Authors: van Wijnsberghe L. , Vandewalle M.
Published: September 2010

A general synthesis of 2, 3‐dialkyl‐1,4‐cyclopentenediones, 2, 3‐dialkyl‐1, 4‐cyclopentanediones and 2‐alkyl‐1, 4‐cyclopentenediones is described. The key intermediates are 2‐alkyl‐3, 5, 5‐trialkoxy‐2‐cyclopentene‐1‐ones, which are easily obtained from 3‐alkyl‐1, 2, 4‐cyclopentanetriones and orthoformic esters.
Acylcyclopentanones: VIII. On the synthesis of calythrone
Authors: Vandewalle M. , van Wijnsberghe L. , Witvrouwen G.
Published: September 2010

A synthesis of calythrone (I) is described starting from 3‐methyl‐1,2,4‐cyclopen‐tanetrione. The total yield is 33%. The key intermediate for the synthesis is 2‐methyl‐3,5,5‐triethoxy‐2‐cyclopentene‐1‐one (V). The method has general applicability for the synthesis of 2‐acyl‐4,5‐dialkyl‐1,3‐cyclopentenediones.
Organometallic Compounds: 27 NMR and mass spectra of hexasubstituted dimetals of group IV B
Authors: Gielen M. , Nasielski J. , Vandendunghen G.
Published: September 2010

The mass spectra of a series of hexaalkyldimetals are described and discussed. The fragmentation rules available in the literature for organometallic compounds of group IV B are also valid here.

The PMR spectra of these derivatives have been recorded and analyzed.
The Influence of Molecular Structure on the Ionization Potential
Authors: van Cauwelaert F. H.
Published: September 2010

Linear relations are reported in the literature between the Taft inductive factors of substituting groups (σ*) and physical constants of molecules like the dipole moment, bond energies etc. A relationship between the ionization potential I(ev) and the Taft factor is also detected when molecules belonging to an homogeneous series of compounds are compared, but the relation is not necessarily linear. In general the ionization potential decreases with increasing negative value of the Taft factors. This is understood in terms of an increased electrondensity on the reaction center. For alkylsubstituents the Taft factors can be corrected (σP) in such a way that a linear relationship between I(ev) and σP is obtained, independent of the nature of the reaction center.
NMR Experiments on Acetals: XXVII. Conformation of Some C–4(6) Alkylsubstituents in 1,3‐Dioxane Derivatives
Authors: Tavernier D. , Anteunis M.
Published: September 2010

NMR shift and coupling parameters were obtained from 4‐alkyl‐1,3‐dioxane derivatives (Et, i.Bu, neoPe, i.Pr in both equatorial and axial positions). 3J coupling constants between the ring hydrogen and the methine or methylene hydrogens of primary alkyl‐groups (“exo coupling constants”) indicate that all these alkyl‐groups prefer a syn clinal (gauche) conformation presumably with respect to the C–O ring bond, and an anti‐periplanar conformation to the C4–C5 ring bond. Semi‐quantitatively, the exo coupling parameters can only be brought into reasonable agreement with expected values, when a low energy difference (∼175 cal) between the gauche and anti conformations in a ROCH2–CH2CH2R unit is accepted.

Attention is further drawn to the overcrowded arrangement of a neoPe group; bond angle deformation and bond opposition strain can be deduced from the experimental data. Substituents, vicinal to an alkyl‐group, influence the conformation of the latter, as shown by a study of isomeric 4‐alkyl‐1,3‐dioxadecalanes (Et, i.Bu, i.Pr).
Distribution des Radicaux dans les Mélanges de Néohexane et de Cyclopentane Irradiés par les Rayons uv et γ à 77°k
Authors: Fauquenoit C. , Claes P.
Published: September 2010

Des mélanges vitreux de cyclopentane et de néohexane ont été irradiés aux rayons γ et UV à 77°K. Les concentrations radicalaires relatives ont été calculées à partir des spectres RPE des radicaux formés. Les distributions radicalaires pour des mélanges de différentes concentrations ont été interprétées. Dans le cas des irradiations UV, la concentration relative en radicaux cyclopentyles évolue linéairement en fonction de la concentration en cyclopentane dans les mélanges; dans le cas des irradiations γ, un écart positif par rapport à la linéarité a été observé, il a été interprété par l'Intervention d'un transfert de l'activation chimique du néohexane vers le cyclopentane.
Séparation des Terres Rares en Dose Macroscopique par Précipitation Sélective de Leurs Complexes Avec L'Acide Hydroxyéthyléthylénediaminetriacetique (HEDTA)
Authors: Merciny E. , Duyckaerts G.
Published: September 2010

Because of the differences in solubility of the simple complexes MeY formed between the lanthanides and HEDTA and because of the differences in the formation constants of the double complexes MeY2Hn(3–n)–, it is possible to separate the rare earths of the ceric group in macroscopic quantities.

From the view point of purity, the best results are obtained for lanthanum (99,5) and neodymium (98,87). Samarium and gadolinium are not separated but are obtained in highly concentrated form. Praseodymium is obtained in impure form containing a considerable amount of neodymium.
Contribution A L'Étude du Spectre D'Absorption Électronique de Complexes Phenols‐Triéthylamine
Authors: Dupont J. P. , D'Hondt J. , Zeegers‐Huyskens Th.
Published: September 2010

The hydrogen‐bond complexes formed by substituted phenols (pKa from 10,25 to 6) and triethylamine are studied in cyclohexane solution at 25°C, by electronic absorption spectrometry. The formation constants of the complexes of 1: 1 stoichiometry are determined by an algebric transposition of the Rose‐Drago method. The constants (K) obey the Hammett relation.

This equation may be compared to the expression found by infrared spectrometry, for the same complexes in carbontetrachloride.

showing that the ρ factor of Hammett is greater in cyclohexane than in carbontetrachloride. The effects of complexation on the electronic transitions are discussed. The extinction coefficients, the oscillator strenghts and the displacements of the 0‐0 transitions are determined for the 1Lb transition and in some case for the 1La and 1B transitions.

The complexation effects on the sub‐vibrational levels are discussed. For all the phenols studied, the complexation causes bathochromic and hyperchromic effects; these effects however are smaller than those produced by the introduction of a substituent into the phenolic ring.

The wave numbers of the maxima of absorption of the phenolate ion in aqueous medium are compared with the wave numbers of the maxima of absorption of the complexes in an aprotic solvent. The values are discussed in terms of formation and dissociation of ionic complexes.
NMR Experiments on Acetals. Part 28. 1,3‐Dioxanes with Non‐Chair Conformations and the 2J(Och2O) Criterium
Authors: Anteunis M. , Swaelens G. , Anteunis‐De Ketelaere F. , Dirinck P.
Published: September 2010

Several 1,3‐dioxanes, not possessing chair conformations (Chart 1), are newly prepared. The PMR data are discussed in terms of possible conformations. Typically 2J(OCH2O) coupling constants are too positive in accordance with disturbed torsional relations between σ(C2–H) bonds and adjacent p(0) lobes. A semiquantitative discussion, relating 2J with presumed torsion ring angles, is given. Thus values for 2J(OCH2O) in carbon disulfide are: — 5.5 cps for a twist conformation, with (idealized) torsion angles of 30° and 60° (form (14)); ‐3.4 cps for a conformation between a chair form a half‐chair form and sofa form (resp. (16) and (17)); and — 4.7 cps for a form close to a classical boat (19) with torsion angles of 0° and 60°.

P.D. and G.S. tank the IWONL for a scholarship.
Nouvelle Voie De Synthèse De Dérivés Substitués En Positions 2 Et 7 Du Pyrène [1]
Authors: Flammang R. , Martin R. H.
Published: September 2010

A new route to 2,7‐disubstituted pyrene derivatives is described. 2,7‐di(ethoxycar‐bonyl) pyrene is synthesized in eight steps from pyrene.
Énergie de Resonance des Chelates et Leur Pouvoir D'Activation de L'Oxygène
Authors: Rouchaud J. , Mawaka J.
Published: September 2010

Several chelates of molybdenum were used as catalysts in the oxidation by oxygen of propylene toward the selective synthesis of epoxypropane. There is a linear relationship between the catalytic activities and the energy of resonance of the catalyst.
La Réduction de L'Oxygène Moléculaire Dans L'époxydation Directe
Authors: Rouchaud J. , Kajangwe V.
Published: September 2010

Several chelates of MoO2+2 catalyze the oxidation by oxygen of propylene dissolved in benzene toward the synthesis of epoxypropane. The catalyst carries and activates oxygen. There are relationships between the catalytic activity, the structure of the chelate distinguished by the Hammett's sigmas relative to the substituents of the benzo‐naphtalenic system of the ligand, and the oxidation level of the heavy element. These relationships specify the catalytic mechanism, the part played by chelation and the energies involved.
Étude en RMN de La Bromo‐2 T‐Butyl Diméthyl‐4,4 Cyclohexanone trans Un Exemple De Couplage 4Jdiaxial
Authors: Richer J. C. , Baskevitch N.
Published: September 2010

La bromo‐2 t‐butyl‐5 diméthyl‐4,4 cyclohexanone trans a été préparée et son spectre de résonance magnétique nucléaire a été examiné. Un couplage à longue distance 4Jdiaxial a été mis en évidence.
Structure Cristalline D'Un Dérivé Du Diphénylcyclopropane
Authors: Meunier‐Piret J. , van Meerssche M.
Published: September 2010

The structure of 1‐[p. Cl‐C6H4], 2‐[p. (CH3)2N–C6H4], l‐CN cyclopropane has been determined by 3D X‐ray analysis. Crystals are monoclinic, P21/c, with unit cell dimensions: a = 9,80 Å, b = 16,67 Å, c = 15,32 Å, β = 138 Z = 4. The structure has been solved by symbolic addition method and refined by least square method. The angles between the 1‐and 2‐phényl groups and the bissector plane of the cyclopropane are respectively 21° and 42°.
Hétérocycles Tellures. I Le Benzo(B)Tellurophène
Authors: Piette J. L. , Renson M.
Published: September 2010

Le benzo(b)tellurophène est obtenu à partir de l'o‐méthyl tellurobenzaldéhyde par la suite de réactions suivantes: quaternisation avec l'acide bromacétique, déquaternisation par chauffage du sel de telluronium, cyclisation en acide benzo(b)tellurophène carboxylique‐2 et enfin décarboxylation.

Les spectres IR, UV, RMN et de masse confirment la structure du benzo(b)tellurophène qui a été également caractérisé par sa T.N.F, son picrate et ses composés d'addition avec les halogènes.
Étude Spectroscopique Des Complexes De Chélation Formes Entre Les Lanthanides Trivalents Et L'Acide Hydroxyéthyléthylénediaminetriacétique
Authors: Merciny E. , Gilbert B. , Duyckaerts G.
Published: September 2010

The study of the 1:1 complexes of HEDTA with different lanthanides is carried out by different spectral methods (RX, infra‐red and Raman spectroscopy) in order to determine their molecular structure.

The behaviour of the alcoholic group of the acid is specially studied; it seemed that, according to the number of coordination sites and the size of the ionic radius of the metal, HEDTA behave like a hexadentate or pentadentate chelating agent. In the last event, the alcoholic group does not take part in the coordination.
Polarography of 3‐Keto‐Sugars
Authors: van Beeumen J. , De Ley J.
Published: September 2010

The polarographic features of several 3‐keto‐sugars were studied. The effects of pH, incubation time, boric acid and concentration were determined. Spectrophotometric measurements were carried out simultaneously.

The structure of 3‐keto‐lactose in aqueous solutions, its chemical conversions at higher pH and the electroreduction mechanism were deduced. There is evidence that the carbonyl function of various 3‐uloses in neutral, slightly acid and basic solutions is hydrated, the degree of hydration varying with the type of the 3‐ulose. As the electroreduction occurs on ly at the free carbonyl function, the limiting current is determined by the dehydration rate. Their polarographic properties indicate that the ketones are readily reducible in a two‐electron process, presumably to the corresponding isomeric sugars. There is strong evidence that reductones are formed in alkaline conditions.
Liquid phase hydrogen abstraction from asymmetrically chlorinated ethanes by chlorine atoms
Authors: Martens G. J. , Godfroid M. , Verbeyst J.
Published: September 2010

The ratios of rates constants of hydrogen atom abstraction by a chlorine atom from both sites of asymmetrical chloroethanes were measured in the liquid phase at −13 to 40 °. The following values were obtained:

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The results are compared with recent gas phase data and discussed.

Experiments in a complexing solvent (CS2) show an increased selectivity compared to the liquid phase due to both enthalpic and entropic effects.
The A2Π ‐ X2Σ+ band system of BeH and BeD in absorption
Authors: Horne R. , Colin R.
Published: September 2010

A description is given of the absorption spectrum in the region between 6000 and 1700 Å of the BeH and BeD molecules obtained in a King furnace. The A2Π ‐ X2Σ+ bands near 5000 Å, observed previously in emission, have been obtained at high resolution in absorption and reanalysed. Improved vibrational and rotational constants are given. Pure electronic energy differences (EΠ ‐ EΣ)BeH = 20 033.19 and (EΠ‐EΣ)BeD = 20 036.11 cm−1 have been derived and show the existence of an electronic isotope shift Δ νe(BeH ‐ BeD) = ‐2.9 ± 1.0 cm−1 which cannot sofar be explained by existing theories. Precise A‐doubling constants of the A2Π sate are also derived.
Theoretical Calculation of the Electronic States of the Molecule LiO
Authors: Liu H. P. D. , Verhaegen G.
Published: September 2010

Ab initio calculations are performed on a serie of valence states of LiO. The calculations are carried out according to the LCAOMOSCF scheme with a basis set sufficiently large so as to furnish energies very close to the corresponding Hartree‐Fock limits. Correlation energies are calculated semi‐empirically using corresponding atomic data. The results are in good agreement with available experimental data concerning the equilibrium internuclear distance and vibration frequency of the ground state. A2 Π ‐ 2Σ+ electronic transition is predicted to lie in the infra‐red region of the spectrum at about 1750 cm−1.
Enthalpies de Formation des Alliages Ternaires Liquides Étain‐gallium‐Indium
Authors: Laffitte Marc , Bros Jean‐Pierre , Bergman Claire
Published: September 2010

Par calorimétrie, nous avons mesuré, à 520 K, les enthalpies de formation des alliages binaires liquides gallium‐indium, gallium‐étain et indium‐étain, ainsi que celles des alliages ternaires gallium‐indium‐étain.

En utilisant la règle empirique de Kohler, nous avons calculé les enthalpies de formation des alliages ternaires à partir des résultats obtenus pour les alliages binaires correspondants; ces valeurs étant en bon accord avec nos résultats expérimentaux, la loi de Kohler est tout‐à‐fait valable dans ce cas et nous en avons déduit les enthalpies molaires partielles des trois constituants du mélange ternaire.
Mesure de Processus À L'Interface Gaz‐Solide par une Technique Thermique Différentielle
Authors: Gosselain P. A. , Jannes G. A. , Simoens G. S. , Slegers J. , Warzée D.
Published: September 2010

On décrit un dispositif permettant la mesure des flux thermiques générés à l'interface solide‐gaz. Un thermocouple enserré entre deux feuilles de mica d'une surface géométrique de l'ordre du cm2 et d'un poids de quelques mg est monté en opposition avec un second thermocouple. Les surfaces de mica du premier thermocouple supportent un film organo‐métallique dont l'interaction avec une phase gazeuse produit l'effet thermique étudié. L'utilisation de ce dispositif a été illustrée par l'étude de la réaction d'hydrogénation de l'éthylène catalysée à l'interface solide‐gaz par un complexe organique du nickel. La relation théorique ΔE = a′v où a′ est une caractéristique du dispositif expérimental et v la vitesse de réaction a été observée de manière satisfaisante pour des vitesses de réaction voisines de 10−8 mole s−1 auxquelles correspondent un signal d'une dizaine de microvolt. Les possibilités et limitations du dispositif sont discutées.
Study of chemi‐ionization in explosions by flash photolysis
Authors: D'Olieslager J. , Lemoine J. , Jaegere S. De
Published: September 2010

A technique is described to investigate the formation of chemi‐ions in flash induced explosions. Data are presented on the ion formation rate and the ion yield in H2/O2/N2/NO2 mixtures at 60 torr, to which traces of C2H6 were added.

The importance of the wavelength of the actinic light for the chemi‐ ionization processes is established by using quartz or pyrex vessels. Using a quartz vessel chemi‐ionization was also observed without any C2H6 present. Most probably this is due to the presence of O(1D).
Étude Théorique des Spectres Électroniques de Dérivés Dithioliques
Authors: Pfister‐Guillouzo G. , Gonbeau D. , Deschamps J.
Published: September 2010

Dans le cadre d'une étude expérimentale et théorique des hétérocycles sulfurés, nous avons abordé l'examen de dérivés du dithiole‐1,3 et du dithiole‐1,2 en utilisant la méthode C. N. D. O. À notre connaissance, aucun de ces composés n'a fait l'objet d'une approche théorique incluant tous les électrons de valence. Les données expérimentales les plus complètes que nous possédions étant les spectres d'absorption de ces composés dans l'ultra‐violet et le visible, nous nous sommes attachés en premier lieu à l'interprétation des spectres électroniques de ces hétérocycles.
Structure Cristalline des Acides O‐Acétylthiophenecarboxyliques
Authors: Griffe M. , Durant F. , Pieret A. F.
Published: September 2010

Crystal structures of the three O‐acetylthiophenecarboxylic acids have been solved from single‐crystal data (recorded on equiinclination Weissenberg films) by a three dimensional X‐ray analysis using heavy atom method and refined by least‐squares procedure to a final R value ≤0.10.

Space groups: carboxy‐2 acetyl‐3 thiophene, P21/m (Z = 2); carboxy‐3 acetyl‐2 thiophene, Pnam (Z = 4); carboxy‐3 acetyl‐4 thiophene, Pbcm (Z = 4).

All the molecules are planar occupying in the cell special positions (m). They are held into molecular planes by C‐H… O and S… O Van der Waals bonds; distances between superposed planes: ± 3.30 Å. Carboxylic and ketonic groups are linked together by intramolecular hydrogen bonds; moreover, the position of the carboxylic hydrogen suggest an important enolic character.
Interpretation of the Spectra of Some Nickel(II)‐Complexes
Authors: Peeters J.
Published: September 2010

The probability of the spin‐forbidden transitions 3B1g→ 1A1g and 3B1g→1B1g has been calculated for the complexes Ni(py)4Br2, Ni(py)4Cl2 and Ni(py)4(ClO4)2. The wavefunctions were derived by means of the crystal field theory (intermediate field scheme) and of the molecular orbital theory. The symmetry of the complexes can be effectively described in the D4h point group.

The evaluation of the L. C. A. O.‐coefficients in the M. O.'s is based on the nefelauxetic effect. Special attention is given to the influence of the halogenide ligands on the intensity of the spin‐forbidden transitions.
A Comparative Cation Exchange Study of the Lanthanide Atrolactate and α‐Hydroxyisobutyrate Complexes
Authors: Thun H. , Verbeek F.
Published: September 2010

In order to compare α‐hydroxyisobutyrate and atrolactate as complexing eluants for the separation of lanthanide ions on cation exchange resins, the distribution constants for a number of their lanthanide complexes were determined simultaneously at 25±0.1 ° and ionic strength 0.2 with ammonium perchlorate in aqueous solution. Column techniques were used to compare the HETP of the Tb‐complex with each ligand. Finally a comparative test separation was carried out on a mixture of lanthanide ions. In view of the results atrolactate should not be considered as a promising alternative for α‐hydroxyisobutyrate as it offers only little improvement.
The System Pb(II)‐Dipicolinic Acid in Aqueous Solution
Authors: Campanella Luigi , Angelis Giorgio De , Napoli Aldo
Published: September 2010

The system Pb(II)‐dipicolinic acid (2,6‐pyridinedicarboxylic acid, H2PC) was studied at 25°C in aqueous 0.5 M sodium perchlorate medium. By the polarographic and spectrophotometric methods the following two equilibria are evidenced:

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The values of the formation constants are:

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for equilibrium (1) and:

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for equilibrium (1).
Un Exemple de L'Utilisation des Complexes Paramagnétiques Dans les Études Conformationnelles
Authors: Grandjean J.
Published: September 2010

We 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

Diglycine 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

In 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

A 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

From 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

The 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

The 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

Procedures 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

N‐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

The 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

This 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

Three 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

Absolute 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

The 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

La 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

The 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

Los 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

Limiting 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

La 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

The 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

The 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

The 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

Sensitization 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

Natural 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

Methyl‐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

Consecutive 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

The 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

The 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

Starting 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

Unsupported 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.