bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxydation Entraînée des Hydrocarbures. I. Influence de la Stabilité des Radicaux Péroxydiques
Authors: Rouchaud J.
Published: September 2010

The reactivity of cyclohexane in the catalyzed autoinitiated oxidation by cobalt naphtenate under an initial partial pressure of oxygene of 11 kg/cm2, in the presence of cumene was studied. The addition of about 5% in volume by cumene in the total volume of the mixture resulted in an increase in the rate of oxidation. In the oxidation of cyclohexane with cumene, the rate was doubled, while in the presence of cumene and a salt of cobalt, the rate of oxydation was 5 times as great. This increase in the rate of oxidation of cyclohexane by the presence of cumene corresponds to the increase in the rate at which this oxidation was initiated. This increase in the rate of initiation results from the increase in concentration of peroxydic radicals which corresponds to the disparition constant of cumyl peroxydic radicals which is about 600 times below the disparition constant of the cyclohexyl peroxydic radicals. The apparent energy of activation in the mixture is 28,5 kcal mol−1 in the temperature range of 130‐60°C.
Oxydation Entraînée des Hydrocarbures. III. Influence des Alcools
Authors: Rouchaud J.
Published: September 2010

In the oxidation of cyclohexane in the liquid phase by molecular oxygen, under the pressure of 11 kg. cm−2, at about a temperature of 150°C and in the presence of 50 ppm by weight in cobalt, the influence of the products of reaction on the rate of oxydation of cyclohexane was studied at different concentrations. The cyclohexanol and cyclohexanone have an accelerating effect while on the other hand, adipic acid reduces the rate of transformation.

In using certain aliphatic alcohols such as ethanol, n‐ propanol and the isomers of butyl alcohol under different initial concentrations, an accelerating effect was observed, and more particularly with the t‐butanol.

In their presence, the rate of reaction is ten times increased for concentrations of alcohol being less than 0.4 mol. l−1. From the schematized, in the liquid phase, competitive oxidation reactions of two substances, by autoinitiated catalysis, an expression of the rate of oxidation of cyclohexane in the mixture was derived. The rate of oxidation of cyclohexane observed when additives are present, is in general twice as higher, than the calculated maximum rate. This divergence is interpreted as an increase in the degree of branching of chains of reactions, following the addition of the additive.
Essais de Chloration Dirigée. VIII. Photochloration des Composés Aliphatiques en Présence D'Additifs
Authors: Rouchaud J. , Bruylants A.
Published: September 2010

Les auteurs ont étudié la photochloration, en phase liquide, de l'isovaléronitrile en présence d'additifs, principalement des amines aliphatiques, aromatiques et hétérocycliques. Ils ont observé des effets de sélectivité. Ainsi la triéhylamine à la concentration 0,5 ml.l−1 conduit à 76% de β‐chloro‐isovaléronitrile et la pyridine à 2 m.l−1 en donne 77%, résultat pratiquement identique à celui obtenu en présence de benzène à 8 m.l−1, c'est‐à‐dire jouant le rôle de solvant.
Étude par Diffraction de Rayons X de Complexes D'Halogénures Alcalins et de Molécules Organiques. VII. Structure de LiCl.C5H5N
Authors: Durant F. , Verbist J. , van Meerssche M.
Published: September 2010

LiCl.C5H5N crystallizes in the orthorhombic system, space group P212121; a = 8.61, b = 17.92, c = 4.02 Å, Z = 4.

The structure has been determined by heavy atom method using 579 reflections of the (hk0), (hk1) and (hk1) planes, refined by Fourier synthesis and least squares method to an R index of 0.161. Each lithium ion is tetraedrically surrounded by three chloride ions and one nitrogen atom. The structure consists of molecular chains (Li+.Cl−.C5H5N)n, parallel to the [001] axis and held together by means of C–H … Cl− bonds.

Distances LiCl: 2.38, 2.39 and 2.38 Å. LiN: 2.01 Å. Mean distances in pyridine: NC: 1.36, CC: 1.39, CC′: 1.40Å. Distance between C5H5N superposed cycles: 3.54Å.
Étude par Spectrométrie Infrarouge de la Complexation de Phénols Substitués par la Triéthylamine
Authors: Lutgen P. , van Damme M. P. , Zeegers‐Huyskens Th.
Published: September 2010

By infrared spectrometric measurements, we have determined the complexation constants (K12) of several complexes formed by substituted phenols with triethylamine in carbontetrachloride solution, at 27°C.

Plot of log K12 in function of the a substitution constant of Hammett show two straigth lines with different slopes. The first line, containing the substituents of group I (3–4 di‐CH3, p.CH3, p.I, p.Br, p.F), obeys the relation magnified image.

The second line, containing the substituents of group II (3–5 di‐Cl, p.CN, p.NO2) follows the relation magnified image.

For the complexes of group I, one may admit the predominance of normal hydrogen bonded complexes of the type magnified image.

Compared with the values of ρ obtained previously for complexes formed by phenols with aniline or pyridine, the value of ρ found in this work is greater owing to the greater enthalpy of complexation.

For the complexes of type II; our results suggest the predominance of an ion‐pair complexe of the type magnified image.

This view is supported by experimental facts such as the variation of colour of the solutions, the diminution of solubility of the complexes and the apparition, in the infrared spectra, of a large band lying between 2900 and 2200 cm−1. This result agrees also with our earlier infrared spectrometric determinations.
Cyclopentanones I. The Synthesis of 2‐Alkyl‐4‐hydroxy‐1‐Cyclopentanones and Derivatives
Authors: Vandewalle M. , Compernolle F.
Published: September 2010

The metal‐ammonia reduction of 2‐alkyl‐4‐hydroxy‐3‐methoxy‐2‐cyclo‐pentene‐1‐ones, (III) gives 2‐alkyl‐4‐hydroxy‐1‐cyclopentanones (IV) and 4‐alkyl‐1, 3‐cyclopentanediols (V).

The former products can easily be dehydrated to 5‐alkyl‐2‐cyclopenten‐1‐ones (VI).
I. Oxydation Du Cumène I. Activité catalytique des composés du cobalt
Authors: Rouchaud J.
Published: September 2010

The oxydation of cumene in liquid phase, at a temperature of about 100°C, by oxygen under a pressure of 730 mm Hg, gives principally the corresponding hydroperoxyde. The oxydation was carried out in the presence of various cobaltic compounds which are completely soluble in cumene at the used concentrations. The chelate of cobalt (II)‐ bis (2,2' hydroxybenzylidene) ethylene diamine, C. Co, catalyses vigorously this oxydation. The rate of reaction is initially high (16 mol.% of cumene transformed an hour for [C.Co] = 10−4 ion g l−1, and falls to 20% of the original value after an hour's reaction, showing thus the intervention of inhibition. The maximum rate of reaction varied following 0.5 power of the concentration in C.Co. The yield in hydroperoxyde as compared to the transformed cumene is above 90% for [C.Co] = 10−4 ion g l−1. The same yield falls to 20% for a metal concentration 50 times greater. For [C.Co] = 1,05. 10−4 ion g l−1, the apparent energy of activation in this oxydation is about 12 kcal mol−1 between 80 and 120°C. The optimum conditions—the best compromise between the rate of reaction and the yield of hydroperoxyde—is using C. Co as compared to the cobalt naphtenate, N.Co, corresponds at 100°C, to a concentration of 2, 1. 10−4 ion g l−4 of cobalt, for which the yields in hydroperoxyde are the same (85%), and the rate of oxydation of cumene 1, 6 times faster in presence of C.Co. The different catalysts used fall under the following sequence in activity: C.Co.>N.Co>Acetate (II) 4 aq.>Sulfate (II) 7 aq. The differences in activity are interpreted by electronic effects and by the solvatation of the catalysts.
II. Oxydation Du Cumène II. Action catalytique des métaux lourds chelatés par une Même base de Schiff
Authors: Rouchaud J.
Published: September 2010

The oxidation of cumene in liquid phase by molecular oxygen at 100°C and under a pressure of 730 mm Hg was carried out in the presence of the chelates of bis (2,2' hydroxybenzylidene) ethylenediamine with cobalt (C.Co), nickel (C.Ni), manganese (C.Mn), iron (C.Fe), copper (C.Cu), and zinc (C.Zn). The hydroperoxide of cumene was formed with a yield on the cumene transformed, decreasing as the concentration of the catalyst increased. With C.Co and C.Mn, the initial rate of reaction corresponds to the maximum rate observed. With the other chelates, a period of induction followed by a period of autoacceleration and slowing down was noted. For every catalyst, the maximum rate of oxidation is of 0.5 order in respect to the catalyst concentration, except for C.Mn for which the order is 0.27. At concentrations greater than those which correspond to the limits of solubility of C.Cu or C.Zn in the cumene, these two last chelates inhibit the oxidation. The results are significant of the intervention of inhibition, which agrees with V = k(a — x)X(1+by)−1 and Vi = ki x, where V and Vi are respectively the rate of formation of the hydroperoxide and of the inhibitor y. a is the initial concentration of hydrocarbon. The rate of oxidation becomes V = k(a — x)1+K−1 × a−K−1 with K = kki−1b−1. The results show (Catalyst, [M]. 105 ion g l−1, K. 102, k.104(mol l−1)−1sec−1, kib. 103 (mol l−1)−1 sec−1, kd.102(mol l−1)−1, 5sec−1): C.Co, 21/5.25/6.3/12. 0/27.4; C.Ni, 21/6.6/2.0/3.01/2.75; C.Mn, 21/2.86/17.3/61.0/207.0; C.Cu, 13.2/14.2/0.357/0.25/0.11; C.Fe, 22/2.86/2.92/10.2/5.75. The kinetic constants indicate that the value of the rate of oxidation depends on the inhibition and on the activity of the catalysts in the decomposition of the hydroperoxide. These kinetic constants explain this observed sequence: Vmax C.Co>C.Mn>C.Ni>C.Cu>C.Fe and for the yield of hydroperoxide: C.Co<C.Mn<C.Cu, C.Ni, C.Fe.
Dielectric Constant of Carbon Tetrachloride and 1,1,1‐Trichloro‐Ethane Mixtures
Authors: van Loon R. , Fuks S. , Bellemans A.
Published: September 2010

The static dielectric constant of CCl4, CH3CCl3 and their mixtures has been measured in the liquid region between −20 and +20°C. Applying the Onsager‐Kirkwood theory and extrapolating to infinite dilution we found 1.73 ± 0.03 debye for the permanent dipole moment of the CH3CCl3 molecule. A weak tendency for parallel alignment of the dipolar molecules was observed for concentrated mixtures in CH3CCl3.
Contribution to the Knowledge of the Electrochemistry of Uranium in Molten LiCl‐KCl Eutectic (): IV. The potential of the couple U(III)/U(0)
Authors: Caligara F. , Martinot L. , Duyckaerts G.
Published: September 2010

We have measured the standard potentials of the system U(III)/U(0), in the molten LiCl‐KCl eutectic, within the temperature range from 400 to 550°C. The cell used has been the following:

magnified image

The work has been carried out in glove‐boxes, under inert atmosphere, and special care has been taken in preventing even the slightest oxidation of U(III).

A comparison has been made with previous results, obtained by different Authors.
L'étude Des Décompositions Thermiques Par Spectrométrie De Masse
Authors: L'Acétone IV. , Collin Jacques E.
Published: September 2010

A mass spectrometric investigation of the thermal decomposition of acetone in a quartz reactor has been undertaken, in the 40–200 microns pressure range, in the absence of a carrier gas. The analysis of the results shows that below 400°C acetone undergoes a dehydration by loss of a water molecule and formation of an allene molecule, in a heterogeneous reaction. The activation energy is found to be of the order of 15 kcal/m. Above 400 °C, the reaction becomes more and more homogeneous and may be explained by a free radical mechanism, although no free radicals could be detected directly. The overall activation energy is of the order of 60 to 70 kcal/m. No secondary reaction leading to methane formation is found to occur in significant amounts.
Extension of the Average Potential Model of Solutions to Systems Submitted to a Moderate Pressure
Authors: Vilcu R. , Bellemans A.
Published: September 2010

Formulas required for using the Average Potential Model of Solutions at finite pressures are deduced from the experimental molar volumes of compressed liquid argon and methane, by applying the theorem of corresponding states. As an illustration the theoretical excess volumes of the simple mixtures argon‐methane and carbon monoxide‐methane are discussed.
PMR Shift Values in β‐Diketone Enol Ethers
Authors: Anteunis M. , Schamp N.
Published: September 2010

PMR spectral shift data make it possible to distinguish the two possible mono enol ethers of β‐diketones i.e.

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Protons located in α position of the “ene” side resonate at lower field than the same protons in the other isomer where they are in α of the “ one” side.
Structure Du Difer‐Sulfonyle‐Octacarbonyle Fe2(CO)8SO2
Authors: Meunier‐Piret J. , Piret P. , van Meerssche M.
Published: September 2010

The crystal structure of Fe2(CO)8SO2 has been determined from three dimensional X‐ray data. The complex crystallizes in space group P21/c of the monoclinic system, with four formula weights in a cell of dimensions a = 8,75, b = 13,19, c = 12,74 Å, β = 113,4°. The SO2 ligand bridges the two groups Fe(CO)4. The iron‐iron distance is 2,717 Å. The average bond lengths are Fe‐C 1,80, C‐O 1,15, Fe‐S 2,22 and S‐O 1,45 Å. The O‐S‐O angle is 114°. The complex possesses approximately the ponctual symmetry 2 mm.
Molecular Orbital Study of Hydrated Titatium Ion
Authors: De Brouckere Guy
Published: September 2010

The electronic structure of the ion Ti(H2O)6+++ has been studied by a self‐consistent Wolfsberg‐Helmholz method. The effect of the Coulomb repulsion between net charges of each atom has been included in the effective hamiltonian. The formal positive charge +3 is shared between the central atom and the ligands in such a way that the charge of Ti becomes of the order of one. The unpaired electron is in a molecular orbital Tg, whose main components are the 3d orbitals of Ti; in agreement with the crystal field theory.
Enolization and Hydrogen Bridge Formation in Cyclopentane β‐Tricarbonyl Systems
Authors: Anteunis M. , Dewaele S. , De Pooter H. , Compernolle F.
Published: September 2010

Protons situated next to the “ene”‐side of enolized β‐diketone systems are less deshielded than when they are situated next to the “one” side in the isomeric enol system. As published before (1) the ethers and esters of the same system show the opposite behaviour. This allows discussion regarding the structure of several cyclopentane β‐tricarbonyl derivatives, in which the different enol forms can be differentiated by I.R. and P.M.R. spectroscopy.
The Thermodynamics of p‐Toluidine and of the p‐Toluidinium Ion: A Mass Transfer Study
Authors: Aboul‐Seoud A.
Published: September 2010

The activity coefficients of p‐toluidine were determined using a modified distribution method. The results were found to conform with the Setchenow relationship, and with the Debye theory of salt effects.

The dissociation constant of the p‐toluidinium ion was determined under different conditions of temperature and salt concentration. The thermodynamic dissociation constant was obtained by extrapolation. The activity coefficient quotient fH+/fp‐toluidinium, (Kb)o and (Kb)m were calculated, and the results were discussed. ΔH, ΔG and ΔS, for the dissociation of the p‐toluidinium ion, were determined.
Studies in Organic Mass Spectrometry. V (1): Keto‐enol tautomerism in mass spectrometry
Authors: Schamp N. , Vandewalle M. , Francque M.
Published: September 2010

Examination of isomeric 3‐propyl‐ and 3‐butyl‐2, 4‐pentanediones demonstrates that the electron impact induced degradation of a β‐diketone molecule is different when it is enolised or not.
Composés Organométalliques IV. Spectres de résonance magnétique nucléaire protonique de dérivés organostanniques (CH3)3SnR′ ()
Authors: Boué S. , Gielen M. , Nasielski J.
Published: September 2010

The P.M.R. spectra of 29 compounds containing a Sn(CH3)3 group have been recorded. The chemical shifts and the coupling constants are related to Tafťs and Hammetťs σ sequences. For polycyclic aromatic tin derivatives, the shift is influenced by the ring current.
Thermodynamics of Mixed Monolayers
Authors: Joos P.
Published: September 2010

From the identity of the chemical potential of each component, including the solvent, in the bulk and the surface phase, the Gibbs equation is deduced. Relations are obtained between surface pressure, adsorptions and molar fractions in the bulk phase. The equations hold both for adsorbed and for spread films. A penetrated film is also considered. The relation between molar fraction and surface pressure was tested for the system Na‐laurate and sapoalbin, having very different saturation adsorption values. Agreement between theory and experiment is satisfactory.
L'Étude Théorique Des Systèmes Périodiques III. L'orthonormalisation des orbitales atomiques
Authors: André J. M.
Published: September 2010

The independence of the core terms on the dimensions of the periodic system is proved in a basis of orthonormalized orbitals, and it is shown that the infinite system can be caracterized by these integrals. The formalism for the orthogonalization of the orbitals and for the calculation of the different integrals in the new basis is described.
Studies in organic mass spectrometry. VI [1]. Influence of alkylsubstituents on the fragmentation of 1,3‐dioxane
Authors: Vandewalle M. , Schamp N. , van Cauwenberghe K.
Published: September 2010

The mass spectra of 1,3‐dioxane and its 2,4,5‐ and 6‐alkyl substituted derivatives are discussed. Two main degradation patterns result respectively from initial elimination of a 2‐hydrogen atom or alkyl substituent and from the expulsion of a formaldehyde molecule. Subsequent fragmentations are highly influenced by the presence of substituents.

4,6‐Disubstituted 1,3‐dioxanes exhibit a distinct and typical fragmentation, starting with the expulsion of a substituent.

Some of the mechanisms proposed are sustained by deuterium labeling.
Organometallic compounds. VI . Electron impact fragmentation of some mixed and symmetrical tetraalkyltins
Authors: Boué S. , Gielen M. , Nasielski J.
Published: September 2010

The mass spectra of mixed tetraalkyltins are described and analysed. The fragmentation pattern is in agreement with the hypothesis of prefered Sn(IV) and Sn(II) valence states in the tin‐containing fragments. These states are reached by losing an alkyl radical from the next higher unfavourable valence state, or by losing an alkene or alkane molecule from a favourable valence state. The ease of cleavage of a carbon‐tin bond in the molecular ion parallels the stabilization of the leaving alkyl radical by hyperconjugation. The findings are tentatively extrapolated to the general behaviour of tetraalkyl derivatives of group IV organometallics.
Enthalpy and entropy changes associated with the ionization of hydroxyethylenediaminetriacetic acid
Authors: Fuger J. , Merciny E.
Published: September 2010

Enthalpy changes associated with the three ionizations of hydroxyethylenediaminetriacetic acid have been measured calorimetrically. The values reported for 25°C and μ = 0.1 (KCl) are ΔH1 = −1.12±0.12, ΔH2 = + 3.09±0.05 and ΔH3 = + 6.65±0.08 kcal.mole−1, respectively. From these data and from the acid dissociation constants, entropy changes are calculated.

The results are compared with literature data obtained by the determination as a function of temperature of the acid dissociation constants.
Mesure du potentiel standard du couple Np(IV)/Np(III) dans l'eutectique LiCl‐KCl entre 400 et 550°C
Authors: Martinot L. , Duyckaerts G. , Caligara F.
Published: September 2010

We have measured the standard potential of the couple Np(IV)/Np(III) in the molten LiCl‐KCl eutectic, within the temperature range from 400 to 55O°C.

The cell used has been the following

magnified image

The work has been carried out in glove‐boxes under inert atmosphere and special care has been taken in preventing even the slightest oxidation of Np(III).
Mechanisms for the cleavage of carbon‐tin bonds. IV [1]. Electrophilic substitution at an olefinic carbon atom
Authors: Baekelmans P. , Gielen M. , Malfroid P. , Nasielski J.
Published: September 2010

The stereochemistry and the rate of the reaction of nine vinylic organotin compounds with iodine has been studied. A highly polar transition state A is suggested in order to interpret the reactivity sequences (1) and (2), the observed salt effect and the retention of configuration of the vinyl group.

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Dosage de traces de plomb par «cocristallisation» avec NaCl et spectrophotométrie
Authors: Gillet A. C.
Published: September 2010

The procedure consists, briefly, in crystallizing a small amount of NaCl out a saturated brine containing the test sample. Lead in solution cocrystallizes quantitatively. After filtration, it is determined by spectrophotometry with 4 (2 pyridylazo) resorcinol.

Among heavy metals, only cadmium interferes. The total sensitivity can reach a few parts per billion.

The results obtained are in good accordance with those given by polarographic and atomic absorption spectrophotometric methods.

The procedure has the advantage of selectivity without needing cyanide. It can be substituted to the classical dithizone method in most cases.
Catalyse Des Oxydations A Chaînes Ramifiées
Authors: Rouchaud J. , Mpiana C.
Published: September 2010

Isobutane (RH) dissolved in acetic acid (RH/AcOH = 0.3 g/g) has been oxidized by molecular oxygen (Po2∼20 atm; Ptotal∼45–55 atm) at 135 and 155°C. Acetone, t‐butylalcohol (t‐BuOH) and methylacetate are the main products. Their distribution does not vary strongly (less than 10%) when the percentage of RH oxidized is between 8 and 25%. In the oxidation initiated by the t‐butyl‐hydro‐peroxide, the ratio R = t‐BuOH/acetone, mol.mol−−1, is about 2.45 at 135°C., and 1.28 at 155°C. The comparison with the results obtained in the thermal decomposition of t‐butylperoxide shows that R measures the relative reactivities of the t‐butylperoxidic radicals towards the abstraction of an hydrogen atom, or towards their own isomerization. The variation of R with temperature measures thus the difference (ΔE = Ea isom ‐ Ea abst) between the energies of activation relative to these two processes, i.e. 11 kcal. mol−−1. The soluble acetates of transition elements (VO+2, Cr+3, Co+2, Ni+2, Ag+1, Cu+2, Mn+2; 4.10−−3 cation g/1 (AcOH, 25°C)) accelerate the oxidation and result in low values for R (the lowest being about the third as that for the initiated oxidation). However, there are two exceptions: copper (II) acetate has no depressive effect on R but accelerates the reaction; manganese(II) acetate leads to the formation of AcOH. Catalysis of the isomerization of the t‐butylperoxidic and t‐butyloxidic radicals, by the salts of transition elements, explains the results. A relationship is observed between the decrease of R and E, through the use of the catalysts, and the paramagnetic properties of these last. That relationship is interpreted by the theory of the catalysis developed by D. A. Dowden.
Une Synthèse Nouvelle De Dérivés Du Benzo[b]Sélénophène
Authors: Christjaens L. , Renson M.
Published: September 2010

Après avoir passé en revue les différents modes d'obtention connus du benzo[b] sélénophène, nous décrivons une méthode nouvelle et générale de synthèse de dérivés de cet hétérocycle. Cette méthode est basée sur la quaternisation de séléno‐éthers substitués en ortho par un carbonyle, au moyen de dérivés de l'acide chloracétique. La formation de l'hétérocycle par déshydratation se produit en même temps que la déquaternisation.
Étude Viscosimétrique De Solutions Électrolytiques a Base De Sulfate De Cuivre
Authors: Claessens P. , Feneau CI. , Breckpot R.
Published: September 2010

It is shown that the viscosity can be correlated with the ional concentration, Γ = ΣMizi2, of concentrated electrolyte solutions such as used in electroreflning and electrowinning of copper provided the molarities and respective valencies be taken for the metal and sulfate ions whilst all excess H2SO4 be accounted for as H+ and HSO4−. The coefficients in the equation η8 = A"Γ½+B"Γ+E"Γ2 are practically independent, at a given temperature, of the uni‐, bi‐, and trivalent ions which have been considered, so that the viscosity can be estimated on basis of the sole composition up to values of Γ as high as 17.

The continuous variation of the free enthalpy of activation ΔG* with the total ional concentration shows also that the viscosity does not depend on the individuality of the cations but only on steric hindrance effects.

Combining the viscosities with diffusion coefficients of copper determined chronopotentiometrically shows that the Stokes‐Einstein law may be used with a good approximation in such concentrated solutions.
The Friedel‐Crafts Acylation Reaction V. Polar and Steric Substituent Effects in the Reaction of Disubstituted Benzoyl Chlorides Carrying a Constant Ortho‐Substituent
Authors: Verbeerst R. , Slootmaekers P. J.
Published: September 2010

Dans le cadre de L'étude de la corrélation structure‐réactivité dans la réaction d'acylation du toluène par les chlorures d'acide, catalysée par le chlorure d'aluminium, nous nous sommes intéressés à L'effet stérique dans cette même réaction. En introduisant un substituant en position ortho dans une série de réactions composée de chlorures de benzoyle substitués en méta et para, nous avons constaté que la constante de réaction subit une diminution. Ce résultat indique que L'état transitoire de la réaction est sensible à L'effet d'encombrement stérique.

Le même effet étudié dans des composés portant des substituants X et Y en positions 2 et 3 est beaucoup plus prononcé dans le cas où un groupement méthyle est placé en position 2 plutǒt qu'un chlore.

L'ensemble des résultats est en accord avec les données antérieures qui indiquent que la réaction de Friedel et Crafts en milieu apolaire est caractérisée par L'intervention de plusieurs intermédiaires réactionnels.
The Friedel‐Crafts Acylation Reaction VI. Kinetic Evidence for the Failure of the Hammett Relationship in the Acylation Reaction With Substituted Benzoyl Chlorides
Authors: Hoornaert G. , Slootmaekers P. J.
Published: September 2010

Ce travail traite de L'effet de substituant dans la benzoylation du toluène par des chlorures de benzoyle substitués en méta ou en para avec le chlorure d'aluminium comme catalyseur. On a essayé d'étendre la série de réactions en y insérant les chlorures de benzoyle avec des substituants caractérisés par un effet mésomère prononcé.

Il est constaté que les réactivités, comparées au chlorure de benzoyle non substitué, n'obéissent pas à L'équation de Hammett bien que la distribution des isomères dans le produit de réaction de chaque membre de la série soit pratiquement constante. Quelques essais cinétiques préliminaires montrent que la benzoylation du toluène à L'aide du chlorure d'aluminium est plus complexe qu'elle n'est souvent proposée. L'ordre par rapport au complexe réactionnel n'est pas unitaire pour tous les chlorures de benzoyle substitués; il semble que même L'ordre par rapport au toluène n'est pas rigoureusement unitaire.

Deux voies réactionnelles sont proposées: la première consisterait en une attaque du complexe chlorure de benzoyle‐chlorure d'aluminium sur le toluène; la deuxième serait caractérisée par la réaction d'un complexe, produit d'une interaction du toluène avec le chlorure d'aluminium complexé à son tour avec le chlorure de benzoyle, sur une autre molécule du complexe de chlorure de benzoyle. Ainsi les constantes de vitesse de deuxième ordre ne représentent pas des valeurs intrinsèques mais sont plutôt des combinaisons de constantes de vitesse et de constantes d'équilibre. Étant donné que les réactivités relatives ont été déterminées sur la base de valeurs de ces constantes de second ordre, il n'est done pas étonnant qu'elles ne s'accordent pas avec la relation de Hammett.
Long Range Phenomena VII [1] Atypical Long Range Paths in 1,3‐Thioxanes and 1,3‐Dithianes
Authors: Gelan J. , Anteunis M.
Published: September 2010

Analogous long range phenomena as observed in 1,3‐dioxanes [2–4] are found in 1,3‐thioxanes and 1,3‐dithianes. Coupling through oxygen is much less than through sulphur in 1,3‐thioxanes. This is of great help in structure elucidation of 1,3‐thioxane derivatives. The special conformation of this ring can be at the basis of this observation. The easy distortion of the ring of the sulphur analogs of 1,3‐dioxanes is illustrated by the fact that the occurrence of these long range phenomena depends strongly of the degree and nature of substitution.
Arseno‐And Sulphocyanines New Classes of Polymethine Dyes [1, 2]
Authors: Depoorter H. , Libeer J. , van Mierlo G.
Published: September 2010

On décrit la synthèse de nouvelles classes de colorants polyméthiniques renfermant dans leur molécule, en tant qu'auxochrome, un groupement

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La structure électronique de ces édifices est commentée, ainsi que leurs propriétés spectrales.
Mécanisme De La Catalyse Dans L'Oxydation Du Propylène En Phase Liquide
Authors: Rouchaud J. , Nsumba P.
Published: September 2010

Several peroxo derivatives of azo chelates of MoO2++ were used as catalysts for the liquid phase oxidation of propylene in benzene (propylene/benzene = 0.63 g/g) at 150°C., under a total pressure of 45 atm and limited to a conversion of 7.5%. High selectivities in epoxypropane are obtained, but are generally similar to that issued from the oxidations catalysed by the corresponding nonperoxo chelates. This suggests a cyclic catalytic mechanism in which, in a first step, the MoO2++ cation is peroxidised by the peroxidic radicals and, in a second step, the olefin is epoxidised by the peroxo chelate. The results obtained in the vapor and liquid phase epoxidations of olefins suggest that in the liquid phase, the high density in peroxidic radicals gives immediately to the catalyst a high efficiency toward epoxidation.
Preparation of the Enantiomers of 2‐Azidoadipic Acid and Their 1‐Monobenzylesters
Authors: Claesen M. , Laridon G. , Vanderhaeghe H.
Published: September 2010

A synthesis of 2‐azidoadipic acid from diethyl 2‐bromoadipate is described. The two enantiomers of 2‐azidoadipic acid were separated by fractional crystallization of the ephedrine and the dehydroabiethylamine salt. The 1‐monobenzylester of this acid was prepared by esterification with phenyldiazomethane and separation of the mixture of esters obtained in this reaction.
Physico‐Chemical Properties of Acid Saponins Surface Dissociation and Surface Potential of Sapoalbin Solutions
Authors: Vochten R. , Joos P. , Ruyssen R.
Published: September 2010

De oppervlaktedissociatiegraad van waterige sapoalbineoplossingen werd langs thermodynamische weg berekend. De metingen werden uitgevoerd in een KNO3 bevattend midden bij pH = 5. Een toename van de oppervlaktedissociatiegraad met de ionensterkte werd aangetoond. Uit de betrekking van Gouy en de oppervlaktedissociatiegraad werd de oppervlaktepotentiaal berekend. Tussen deze laatste en de stabiliteit van de gas‐vloeistof dispersies bestaat er een duidelijk verband. We moeten hier echter opmerken dat de formule van Gouy niet vrij is van alle kritiek. Aangezien de ionen die zich in het krachtveld bevinden zelf het krachtveld helpen opbouwen is de rechtstreekse toepassing van de verdelingswet bij de afleiding van de betrekking van Gouy een betwistbaar punt. De verdelingswet zou slechts toepasselijk zijn wanneer de potentialen kleiner zijn dan 25 mV. De exacte uitwerking wordt echter bemoelijkt door onoverkomenlijke wiskundige moeilijkheden [3].
Synthèse et Propriétés D'oxadiazoles‐1,2,4 Halogénés
Authors: Eloy F. , Deryckere A. , van Overstraeten A.
Published: September 2010

Des halogéno‐3 oxadiazoles‐1,2,4 ont été obtenus en traitant les dérivés aminés correspondants par l'acide nitreux en présence d'acide chlorhydrique ou d'acide bromhydrique.

Leurs propriétés ne correspondant pas à celles décrites dans la littérature pour les mêmes composés, leur structure a été prouvée et celle des produits précédemment décrits a été réfutée.
Étude par R.M.N de haute Résolution de l'État Adsorbé. II. Orientation Moléculaire Dans Les Micropores Saturés
Authors: Derouane Eric G.
Published: September 2010

Adsorbed systems have been shown to be composed of three distinct N.M.R. phases (I). An increase in linewidth has been observed for well defined amounts of adsorbates (10‐θ–15). These effects can be intimately correlated to the micropores structure of the adsorbent. This increase in linewidth corresponds to an increase of the spin‐spin interaction between neighbouring nuclei and is assigned to a diminution of the molecular mobility as the micropores approach their saturation point. This effect can be used to determine molecular orientations in the saturated micropores.

An evaluation is obtained of the thickness of the benzene ring along its sixfold axis. Alcohol molecules are shown to be parallel to the surface to which they are bound through their ‐OH groups. The 2,2‐di‐methyl‐butane is shown to be in the micropores in the form of a steric dimer.
Organometallic Compounds. XI. Synthesis and Properties of a Series of Racemic Tetraalkyltins
Authors: Boué S. , Gielen M. , Nasielski J. , Lieutenant J‐P. , Spielmann R.
Published: September 2010

Nine new racemic organotin derivatives: MePriPrSnR (R = Br, Et, Bu, iBu, sBu, tBu) and MeiPrcycloHexSnR′ (R′ = Br, Et, anisyl) have been synthesized in high yields. Their mass spectra and those of some intermediates are given and discussed on the basis of previous results.
Physico‐Chemical Properties of Acid Saponins. Relation Between the Gibbs Elasticity and the Stability of the Gas‐Liquid Dispersions
Authors: Vochten R. , Ruyssen R.
Published: September 2010

Op grond van theoretische afleidingen werd aangetoond dat de vergelijkingen van Langmuir, Von Szyszkowski en Frumkin kunnen toegepast worden op geadsorbeerde films zowel gedissocieerde als niet gedissocieerde. De Gibbs elasticiteit kan worden uitgedrukt als een funktie van de verhouding C/a die rechtstreeks volgt uit de toepassing van de vergelijking van Von Szyszkowski (C = koncentratie; a = adsorptiecoefficient). De elasticiteit werd nagegaan en betrokken op de schuimstabiliteit in funktie van pH, koncentratie aan sapoalbine en koncentratie aan KNO3.

Een kwalitatief verband tussen de Gibbs elasticiteit en de schuimstabiliteit werd aangetoond in funktie van de pH met een scherp maximum bij pH 3.5. In aanwezigheid van minerale zouten treden afwijkingen van het parallel verloop op. Eveneens werd de minimale elasticiteit afgeleid die vereist is ter vorming van een stabiele gasdispersie.
The Friedel Crafts Acylation Reaction. VIII. Elucidation of Reaction Intermediates by a Kinetic Study of the Behaviour of the Aromatic Reacting Hydrocarbon and an Analysis of Solvent Effects
Authors: Hoornaert G. , Slootmaekers P. J.
Published: September 2010

Dans ce travail des expériences cinétiques sont décrites qui ont pour but d'élucider si le complexe du chlorure de benzoyle avec le chlorure d'aluminium s'associe réellement avec certains corps présents dans le milieu réactionnel.

Les résultats concernant l'ordre cinétique de l'hydrocarbure réactif aussi bien que les influences de quelques solvants aromatiques sur la vitesse de réaction, peuvent être interprétés par une telle association. Toutefois les effets ne sont pas prononcés et l'on ne peut pas nier d'autres interactions physiques et chimiques des solvants.

D'après des expériences spectroscopiques et cryoscopiques de solutions de chlorure de benzoyle et de chlorure d'aluminium dans le nitrobenzène, le catalyseur serait préférentiellement complexé avec le solvant sous forme monomère. Les résultats concernant l'ordre de l'hydrocarbure et les effets de solvants en présence de nitrobenzène sont comparables avec ceux des milieux moins polaires. Même dans un milieu très polaire l'intervention cinétique de formes ioniques libres a probablement peu d'importance.
Alcaloïdes Indoliques. XIX. Un Nouvel Exemple D'empêchement a la Libre Rotation Dans des Dérivés Dihydroindoliques N‐Formylés
Authors: Hootele C. , Braekman J. C.
Published: September 2010

The proton magnetic resonance spectra of some N‐formyl dihydroindole derivatives have been investigated. The data are best rationalized on the basis of a hindered rotation about the N–CHO bond.

The attribution of the signals to each conformation is obtained from the chemical shifts in the low field region and from the pattern of the aromatic protons.
Physico‐Chemical Properties of Acid Saponins. The Surface Shear Viscosity of Adsorbed Films Of Sapoalbin at the Air‐Solution Interface
Authors: Vochten R. , Ruyssen R.
Published: September 2010

Daar de oppervlaktedilatatieviscositeit functioneel verbonden is met de Gibbselasticiteit, werd onrechtstreeks aangetoond dat de oppervlaktedilatatieviscositeit een belangrijke bijdrage levert tot de schuimstabiliteit. Deze zienswijze wordt versterkt door het feit dat er tussen de gemeten oppervlakteafschuifviscositeit en de schuimstabiliteit geen enkel verband kon worden aangetoond.

Dit verband werd onderzocht in functie van de pH en de concentratie van sapoalbine en KNO3.

Eveneens wordt er gewezen op een mogelijke overgangstoestand in de geadsorbeerde films bij relatief lage pH waarden.
Organometallic Compounds. XIV. Representations of Intramolecular Rearrangements of Octahedral Complexes Via Digonal Twists
Authors: Gielen M.
Published: September 2010

Representations are given for the intramolecular isomerizations of six‐coordinate structures (123,456) via digonal twists. For simpler systems, topological descriptions may be used: this is illustrated by one example (113,356).
Synthèses et Propriétés d'Acides Ortho‐Cétoniques et de Leurs Dérivés
Authors: Christiaens L. , Renson M.
Published: September 2010

Nous avons synthétisé un certain nombre d'acides cétoniques ainsi que certains de leurs dérivés (chlorures, esters normaux et cycliques). Grâce au comportement chimique de ces acides, nous dégageons une structure probable pour ces substances tautomères. Cette structure sera établie avec certitude dans un travail ultérieur par des mesures physico‐chimiques réalisées sur tous les dérivés synthétisés ci‐dessous.
Étude Théorique des Systèmes Hétéroatomiques Conjugués. I. L'évaluation Semi‐Empirique des Paramètres
Authors: Aussems C. , Jaspers S. , Leroy G. , Remoortere F. Van
Published: September 2010

The classical parameters of the nitrogen and oxygen atoms in their characteristic valence states are evaluated semi‐empirically in the formalism of the LCAO — SCF — MO method using a few molecular empirical data.
Essais de Chloration Dirigée. XI. Photochloration d'Acétates d'Alkyles En Milieu Complexant [1]
Authors: Ph. Soumillion J. , Bruylants A.
Published: September 2010

Selectivity of chlorination of aliphatic chains varies within large limits if reactivity of the hydrogen abstractor radical is modified in the rate determining step:
equation image
The reactivity can be caused to change by performing chlorinations in aromatic solvents which are able to complex with atomic chlorine.

First isobutyl acetate [(CH3)2CHCH2OCOCH3] was chlorinated photochemically in various benzene derivatives at various concentrations. Experimental results, expressed in terms of relative reactivity of tertiary hydrogen versus primary [r.r.(t/p)], could be rationalized as follows:
equation image
Secondly a series of alkyl acetates was allowed to react in the same manner but in benzene alone at fixed concentration.

Results obtained in this way were correlated using the equation:
equation image
with p* = −1,39 and h = +0,106.
Oxydation sélective de thio‐1 et séléno‐1 chromènes. obtention de thio‐1 et séléno‐1 coumarines, de formyl‐2 benzo(b) thiophènes, de formyl‐2 benzo(b) sélénophènes et d'autres isomères
Authors: Ruwet A. , Meessen J. , Renson M.
Published: September 2010

The thio‐1 and seleno‐1 coumarins are now obtained by cyclization of the appropriated cinnamic acids [1]. We find a second general method by the selective oxidation of thio‐1 and seleno‐1 chromens [2]. This reaction leads to several products but we find how to favour the formation of the wished compounds by the choice of the oxidant, of the solvent and of the temperature. We describe the ways giving good yields of thio‐1 coumarins, seleno‐1 coumarins, formyl‐2 benzo(b) thiophenes, formyl‐2 benzo(b) selenophenes and other substances.
2,4‐Dioxabicyclo‐[3.3.1]‐Nonane. A Distorted Chair form Having a Non‐Classical Long Range Coupling VII. Long Range Phenomena [1]
Authors: Swaelens G. , Anteunis M.
Published: September 2010

The P. M.R. spectrum of the title compound (I) could be unraveled by multiple irradiation. The protons i, e (I) are involved in a long range coupling (4J(e, i) = 2.2 c.p.s.), which does not follow a planar zigzag path, even in the distorted chair. Arguments are advanced, proving that the two cycles exist in flattened chair conformations.
Étude théorique des systèmes hétéroatomiques conjugués. II. quelques composes contenant des atomes d'azote et d'oxygène
Authors: Aussems C. , Jaspers S. , Leroy G. , van Remoortere F.
Published: September 2010

The semi‐empirical LCAO—SCF—MO method described in the first paper of this series is applied to the molecules of indole, imidazole, indolizine, carbazole, benzfuran and dibenzfuran.
The Electrochemical and Thermodynamic Behaviour of Transition Metal Sulfides
Authors: De Ranter C. , Breckpot R.
Published: September 2010

The sulfides of Fe, Co and Ni, as obtained by precipitation in aqueous solution at low acidity, are X‐ray amorphous. Their Me/S ratio may be altered within very large limits by electrochemical polarization of the suspended sulfide. An apparent equilibrium potential versus the metal or sulfide ions is set up, function of the Me/S ratio. On the sulfur rich side metal depletion is limited by the segregation of rhombic sulfur; on the metal rich side the normal Me/Me+ +potential is reached at compositions Fe.1.04S, Co9S8, Ni3S2 above these amorphous superactive metal is deposited.

The ΔG and ΔH data, obtained from half‐cell voltage measurements and enthalpometric titrations, correspond with the literature values for the crystalline compounds indicating that the short‐range order is similar in both. Attention is drawn to the interesting difference between the bonding of the metal partner in Co—S and Ni—S in connection with hydrometallurgical developments.
Benzotriazole n‐Oxides
Authors: Hubert A. J. , Anthoine G.
Published: September 2010

The oxidation of 1‐(pyrid‐2‐yl)benzotriazole gives an N‐oxide in which the oxygen atom is probably in position 3 of the benzotriazolyl group (II). The photoisomerization of this compound gives another N‐oxide: it is probable that the oxygen atom migrates from position 3 to position 2 of the benzotriazolyl group. Another isomeric N‐oxide (I) is obtained by condensation of 2‐chloropyridine N‐oxide with benzotriazole.
Obtention de cétones et aldéhydes aromatiques substitués possédant en ortho une fonction thioéther ou sélénoéther en vue de la synthèse d'hétérocycles sulfurés et séléniés
Authors: Ruwet A. , Renson M.
Published: September 2010

The synthesis in great quantity of o‐methylthio and o‐methylselenobenzoic acids, substituted in position 3,4, 5 or 6, is investigated from the corresponding anthranilic acids. The ways giving good yields of derived benzaldehydes, benzophenones and acetophenones are described. Through these substances, the thio‐1 and seleno‐1 coumarins and different heterocyclic compounds are now easily obtainable. O‐ benzylthio and o‐benzylselenobenzaldehydes and other interesting starting substances are also prepared.
La cinétique de précipitation des sulfures de cobalt et de nickel par l'hydrogène sulfuré
Authors: Joris Serge
Published: September 2010

La précipitation par l'acide sulfhydrique des sulfures de cobalt et de nickel, en milieu faiblement acide, est caractérisée par l'existence de longues périodes d'induction. Des études structurales et cinétiques permettent d'affirmer que ce lent processus de nucléation est causé par la formation initiale d'une faible quantité de Co(SH)2 et Ni(SH)2.

Les sulfhydrates se transforment ensuite en CoS et NiS amorphes qui servent de support à la précipitation des sulfures cristallins respectifs. Pour chacun de ces composes, la réaction est d'abord autocatalysée par la surface et ensuite inhibée par l'acidification croissante de la solution. L'ion HS− constitue l'espèce sulfurée réagissante.
Comportement de l'aluminium dans l'eau oxygénée concentrée
Authors: Clerbois L. , Clerbois L.
Published: September 2010

The electrochemical behaviour of aluminium in concentrated hydrogen peroxide has been studied by measuring the electrode potentials and the “corrodance”, i.e. the inverse of polarization resistance.

Electrode potentials are very affected by the presence of chloride and nitrate whereas “corrodance” determination is a convenient method for the rapid measurement of the very low corrosion rate of aluminium in hydrogen peroxide.
NMR Experiments on Acetals: XVIII [I]. Cis‐Trans Equilibria in Some 2,4‐Disubstituted 1,3‐Dioxolanes
Authors: Rommelaere Y. , Anteunis M.
Published: September 2010

Thermodynamic parameters for the cis‐trans equilibrium of 2, 4‐disubstituted 1, 3‐dioxolanes were evaluated using gaschromatographic data. The equilibrium is always close to 60:40 (cis:trans), and only very slightly dependent on the nature of the substituents. The t. butyl group substituted in dioxolanes has no anancomeric (biasing) effect.
Les Variables D'État en Thermodynamique
Authors: Steinchen A.
Published: September 2010

In the present paper, we discuss the fundamental problem of the choice of the thermodynamic variables.

In the systems consisting in uniform phases, the Gibbs‐phase rule permits one to define the number of variables at equilibrium.

In non uniform systems, the problem is more complicated. A multilayer model allows to describe the orientation effects in systems by means of new variables as the dipole moments.

The charged and polarized double layers may be usefully treated by the local thermodynamics method. The balance equations show that an electric variable as the polarization is to be taken into account. In the layers where there is specific adsorption, the usual local variables are unnable to describe the local state of the matter. The thermodynamic quantities of each volume element of the layer are functionals of the concentrations.
Temperature Dependence of The Solubility and Complex Formation of Silver Chloride in Dimethyl Sulfoxide
Authors: Rumbaut N. A. , Peeters H. L.
Published: September 2010

The temperature dependence of the solubility product of AgCl in pure dimethyl sulfoxide in the range 25 to 70°C has been investigated. Thermodynamic values at zero ionic strength are estimated. Formation constants for the AgCl2− complex, existing in excess chloride are also tabulated as a function of temperature. The entropy and enthalpy data thus obtained are discussed in terms of ionic solvation.
Synthèse de Sélénoéthers Orthocarbonyles et de Benzo(b)Sélénophènes Dérivés
Authors: Christiaens L. , Renson M.
Published: September 2010

Nous décrivons une nouvelle voie d'accès au cycle benzo(b)sélénophène. Cette méthode est basée sur la réaction d'acétals halogénés avec le sélénium via les organo‐métalliques.

Nous examinons ensuite diverses voies de synthèse qui ne donnent pas de résultats satisfaisants.

Enfin, nous généralisons d'avantage la méthode de quaternisation décrite précédemment.
Spectrophotometric Study of N,N′‐bis(m‐Sulphobenzyl) Dithio‐Oxamide as a Reagent for Cobalt (II)
Authors: Janssens A. A. , Herman M. A.
Published: September 2010

The complex formed between N, N′‐bis(m‐sulphobenzyl)dithio‐oxamide and cobalt (II) can be used for the spectrophotometric determination of traces of this metal in aqueous solution.

The absorbance measurements are carried out at 400 mμ in a buffered solution of pH 10. Beer's law is obeyed over the range 0,3 to 5 μg of Co per ml and the sensitivity is 0,0042 μg of Co per sq. cm., Cd2+, Cr3+, Cu2+, Hg2+, Mn2+, Ni2+, Pb2+, Pd2+, Rh3+, and Zn2+ interfere strongly.