bluuebunny/crossref_metadata_2025_split huggingface dataset:
Étude, Par Spectrométrie Raman, De La Complexation Du ZnCl2 En Solution Aqueuse
Authors: Gilbert B. 
Published: September 2010

AbstractWe have examined by Raman spectroscopy the autocomplexation of ZnCl2 solutions. Our experiments are in good agreement with previous results. A detailed investigation of the intensity of the band located at about 284 cm−1 has allowed us to confirm the presence of the species ZnCl4− and ZnCl2 at concentrations respectively above 1 M and 4 M.The dissociation constants of the following reactions have been determined:magnified image
N. M. R. Experiments on Ketals. XI (1): Shifts of acyclic and cyclic ketals
Authors: Anteunis M. , Borremans F. , Gelan J. , Heyndrickx L. , Vandenbroucke W. 
Published: September 2010

AbstractShift values of the methyl and methylene protons of dimethylketals and dioxolanes of cyclic and acyclic carbonyl compounds are affected by substitution, f.i. the ring size in 1, 3 dioxaspiranes. No simple relation could be obtained, and the influence of ring strain (bond hydridization) is not important. The difference in the general trend between dioxolanes and dithiolanes is observed. No simple theory concerning shift dependence on fairly remoted magnetic anisotropy seems possible.
Isolation and Identification of the Amines Resulting From Chemical and Catalytic Reduction of 20‐Hydroxyimino‐Steroids (Restatement)
Authors: Van Woude G. De , van Hove L. 
Published: September 2010

AbstractSodium‐propanol reduction of 3β‐hydroxy‐5‐pregnen‐20‐one oxime affords the two 20‐amino epimers in a ratio 20 α to 20 β equal to 1.3, while hydrogenation with platinum in acetic acid gives a mixture of the two corresponding saturated amines in the ratio of 2:1.Quantitative separation of 20‐amino epimers is conveniently achieved by chromatography on silica gel.Thin layer chromatography, optical rotatory dispersion, infrared absorption, nuclear magnetic resonance data are joined.
The Surface Shear Viscosity of Mixed Monolayers Interaction Between Cholesterol and Digitonin
Authors: Joos P. , Vochten R. , Ruyssen R. 
Published: September 2010

AbstractA theory is developed to calculate the surface shear viscosity of a mixed film if the flow parameters of each single component are given. This theory starts from the model of Eyring, assuming that the free energy of viscous flow for the mixture is proportional to the mole fractions of the component in the surface and to the free energy of viscous flow of the single components. To test this equation the surface viscosity of mixed adsorbed films of two saponins, digitonin and senegin is considered. Large deviation from this behaviour, as in the case of dilute cholesterol monolayers penetrated by digitonin, points to an interaction.
Magneto‐Chemical Studies on Some Aromatic Carbonyl Compounds
Authors: Gupta R. R. , Mital R. L. 
Published: September 2010

AbstractA survey of the literature reveals that the magnetic data on the substituted aromatic aldehydes and ketones is very meagre and no systematic magneto‐chemical investigation appears to have been made on them. Therefore these aromatic carbonyl compounds form an interesting series for magneto‐chemical studies.These studies may throw some light on the effect of delocalisation of the electrons, the mesomerism of the carbonyl group, the positional isomerism and the interactions introduced by the substitution in the benzene ring.In the present studies the diamagnetic susceptibility of a number of the aromatic aldehydes and ketones has been measured with a sensitive Gouy balance. The magnetic susceptibilities of these compounds were calculated with the help of diamagnetic constants of atoms and multiple bonds as given in Ingold's book (1) also. A comparison between the experimentally determined and calculated χM values shows a poor agreement which may be attributed to the effects of the delocalisation of electrons, the mesomerism, the positional isomerism and the interactions of the substituent groups.In these compounds m‐isomer is comparatively more diamagnetic than ortho and para isomers although Bhatnagar and coworkers (2) have considered ortho isomer more diamagnetic than meta and para isomers, but in these aromatic carbonyl compounds m‐isomer may be regarded more diamagnetic on account of the electron with‐drawing‐nature of the carbonyl group. This is an analogous case to aryl β‐chlorovinylketones as studied by us (3).Yang's method (4) has been applied to evaluate the contribution towards molecular diamagnetism of the carbonyl group.
Organometallic compounds. V. Mass spectra of some aryltrimethyltins
Authors: Gielen M. , Nasielski J. 
Published: September 2010

AbstractThe mass spectra of a series of aryltrimethyltins are described and analysed. The main features are: a relatively weak molecular ion, a very important ArSnMe2+ ion (base peak), a low intensity ArSnMe+ fragment and a non negligible ArSn+ peak. These findings may be related to the well known stable valence states of tin (IVSn and IISn) and the unfavourable IIISn and ISn states. Whereas a methyl group is easier to cleave from the ArSnMe3+ ion than the phenyl radical, n‐butyl seems to be more strongly bound to the metal than the aryl moiety in ArSnnBu3+.The spectra of three aryltrimethylsilicons, recorded in the same conditions, show stronger molecular ions and weaker divalent fragments than in the corresponding tin derivatives.An interpretation of these various findings is attempted in terms of bond energies and electron delocalization.
Synthèse de pyrimidines et de thiazolo[5,4‐d]pyrimidines. II. Analogues de la succinoadénine
Authors: Brocas‐Neuwels Mme H. , Promel R. 
Published: September 2010

AbstractTwo new analogs (III and VII) of succinoadenine have been synthesized. Starting from 7‐chlorothiazolo[5,4‐d]pyrimidine (I), the first one has been prepared by reaction with diethyl D,L‐aspartate, followed by alkaline hydrolysis. On the other hand, direct amination of 7‐methylthiothiazolo[5,4‐d]pyrimidine (IV) with D,L‐aspartic acid has given a product formulated as 5‐formamido‐4‐mercapto‐6‐methylthiopyrimidine (V). An authentic specimen has been prepared for comparison by formylation of 5‐amino‐4‐chloro‐6‐methylthiopyrimidine (VIII) and replacement of the chlorine atom with sodium hydrosulfide.The second analog has been obtained either by reaction of 7‐chlorothiazolo[5,4‐d] pyrimidine (I) with D,L‐mercaptosuccinic acid or by alkylation of 7‐mercapto‐thiazolo[5,4‐d]pyrimidine (VI) with D,L‐bromosuccinic acid.
Nmr Experiments on Ketals XIII [1]. Pmr Features and Relative Sign of Coupling Constants of 4‐Phenyl‐6‐Methyl‐1,3‐Dioxane
Authors: Feeney J. , Anteunis M. , Swaelens G. 
Published: September 2010

AbstractIn accordance with expectation, it is found that 2J5 is of opposite sign to the vicinal coupling constants 3J4,5 and 3J6,5 in trans‐4‐phenyl‐6‐methyl‐l,3‐dioxane From the coupling values it is found that the conformational energy term for 4‐phenyl is roughly the same as that for a methyl group. Some previously mentioned [5, 6] long range couplings through four and five bonds are also found in this substance.
Catalyseurs D'Oxydation I. Influence De La Coordinence Sur L'Activité Des Chélates D'Éléments De Transition
Authors: Rouchaud J. 
Published: September 2010

AbstractDifferent chelates of the transition elements, resembling to the metallic enzymes, were investigated for their catalytic activities in the oxidation, by molecular oxygen (1 atm) at 100°C., of liquid cumene. Cumylhydroperoxide is the main product. Catalytic activity was measured from the increase of the rate of reaction, and the decrease of the yield in hydroperoxide (relatively to the amount of cumene transformed) following the use of the catalyst. The ligands of Co (II), Ni (II.), Mn (II,), Cu (II), Fe (II) and Cr (III) were (successively: the ligand, the ratio ligand: cation, and the coordinence of the chelate: 1) salicylaldehyde ethylenediimine, 1:1, 4; 2) diazoic pigments, 2:1, 6; 3) formazylic complexes, 1:1, 4. Comparison has been made between the activities of these chelates, and that of the corresponding naphtenate and stearate. The chelates of the same cation bound to different ligands have equal activities when the coordinence is the same. The relative catalytic activities of the complexes—of the same cation—of coordinence 2, 4, and 6 are respectively about 4, 5, 3, and 1.
Étude Théorique Des Dérivés Azotés Des Hydrocarbures Conjugués Alternants IV. L'évaluation Des Paramètres α Et β De Hückel Dans Les Dérivés Azotés Des Hydrocarbures Conjugués
Authors: Leroy G. , Aussems C. , van Remoortere F. 
Published: September 2010

AbstractThe matrix elements HSCFpq obtained by the method described in the previous papers are analysed and classified in order to establish rules for the determination of the Hückel parameters α et β of any aza‐derivatives of the conjugated hydrocarbons.
Spectrophotometric Determination of the Dissociation Constant of N, N′‐Bis(2‐Sulphoethyl) Monothiooxamide and N, N′ ‐Bis(Parasulphobenzyl) Monothiooxamide
Authors: Goeminne A. M. , Herman M. A. 
Published: September 2010

AbstractThe dissociation constant of N, N′‐bis(2‐sulphoethyl) monothiooxamide and N, N′‐bis (p.sulphobenzyl) monothiooxamide was determined by a spectrophotometric method, using a weighted least squares technique for the calculations. The values of the thermodynamic dissociation constant are respectively pKT = 11.97 and pKT = 11.67.
Catalyseurs D'Oxydation II. Activité Et Configuration Électronique
Authors: Rouchaud J. 
Published: September 2010

AbstractThe catalytic activities of the enzyme‐like chelates of transition elements, towards the oxidation by molecular oxygen of liquid hydrocarbons (cumene, 100 °C, 1 atm) has been related to the electronic configuration of the complexes. The ligands were salicylaldehyde‐ethylenediimine (C), azoïc pigments (A), formazanic compounds (F), and the salts of naphtenic (N) and stearic acids (S). The theory of catalysis developed by Dowden was applied to the oxidations. The catalytic activity, which results from electron transfer from the hydroperoxide or peroxidic radicals to the catalyst, depends on the energy and entropy of the exchange. From the measurement of magnetic susceptibilities, the number of unpaired electrons (n), and the electronic configuration of the complexes were deduced. A and C induce a high ligand field, which is measured by the high splitting energy of the 3d orbitals of the cation. With these ligands, n is minimum (successively: ligand, cation+2 — but Cr+3, n): C Co, 1; A Co, 1; N Co, 3; C Ni, O; S Ni, 2; C Mn, 1; S Mn, 5; C Cu, l; F Cu, 1; A Cr, 3. The intensity (∫ϵdγ) of absorption of light (14 – 29.103 cm−−1) by the ligands is increased through metallization: by a coefficient of 3.4 to 5.2 for C, and 1.7 for A. This is to be ascribed to charge transfer, i.e. electron transfer from the ligand to the central cation. All these properties explain, in accordance with the theory of catalysis in oxidation, the decrease of the catalytic activity of the transition elements through chelation (energy and entropy factors: vacancy of low energy orbitals and number of them). Results suggest however that means of activation (such as actinic light) can confer high activity to these chelates.
The Friedel‐Crafts Acylation Reaction IV. Multiple Substituent Effect in the Friedel‐Crafts Acylation of Toluene With Disubstituted Benzoyl Chlorides
Authors: Slootmaekers P. J. , Verbeerst R. 
Published: September 2010

AbstractNous avons étudié L'effet de substituants dans la réaction d'acylation de Friedel‐Crafts dans le cas du toluène en solution dans L'ortho‐dichlorobenzène. Nous avons utilisé des chlorures de benzoyle substitués en position 3, 4 et 3, 5 ainsi que le chlorure d'aluminium comme catalyseur.La relation de corrélation de Hammett n'est pas vérifiée même pour des termes de la série réactionnelle portant des substituants en position 3, 5. De plus, dans cette série de réactions, L'effet des substituants est caractérisé par une dispersion prononcée méta‐para. Lors de L'étude d'une relation linéaire fonction de L'énergie libre, on observe des écarts importants au principe d'additivité des effets de substituants comparé à L'effet de substituant du chlorure de benzoyle. L'analyse des résultats révèle que aussi bien L'écart par rapport à la relation de Hammett que L'écart par rapport au principe d'additivité sont plus importants pour les termes de la série de réaction où le groupe fonctionnel est le plus déficient en électrons. Ces termes semblent répondre en première approximation à une réaction de second ordre. Tous ces faits peuvent être interprétés en admettant L'existence de plusieurs agents d'acylation effectifs, dont L'un est de structure ionique, par exemple une paire d'ions, et dont L'importance relative dans la réaction globale d'acylation est déterminée par les substituants présents dans le chlorure de benzoyle.
Determination of Diethylamine‐Hci With Hypobromite
Authors: Velghe N. , Claeys A. 
Published: September 2010

AbstractLa détermination de diéthylamine‐HCl par titrage ampérométrique avec de L'hypobromite a été étudiée. L'influence du pH, de la vitesse de titrage et du prétraitement de la micro‐électrode tournante en platine a été contrôlée.La méthode, appliquée pour des concentrations variant de 5.10−−2 à 5.10−−4 M en amine, et contrôlée par deux méthodes classiques, donne des résultats d‚une précision excellente.
Aromatic Electrophilic Substitution VIII [1]. Ortho Effects in the Iododestannylation of Phenyltrialkyltins
Authors: Nasielski J. , Buchman O. , Grosjean M. , Schurter J‐J. , Vandendunghen G. 
Published: September 2010

AbstractIt is shown that one ortho methyl group has a weaker accelerating effect than a para methyl group in the iododestannylation of phenyltrialkyltins, whatever the size of the alkyl chains bound to the tin atom. Two ortho methyl groups lead to a rate which is exactly that calculated assuming additivity of the effects, when the leaving group is Sn(CH3)3. If Sn(nPr)3 is the leaving group, 2, 6‐disubstitution leads to a small but significant increase in rate. The results are interpreted in terms of overcrowding in the reactant, and of relief of strain in the transition state; the observed effects are however smaller here than in the case of similar silicon derivatives, and the difference is attributed to the difference in carbon‐metal bond lengths.
Long Range Phenomena VI [1] CIS‐ and Trans‐Isomers of Ethylheptenoates
Authors: Anteunis M. , De Bruyn A. , De Pooter H. , Verhegge G. 
Published: September 2010

AbstractUse of the NOE (Nuclear Overhauser Effect) made a choice possible between the cis‐trans isomers A and B of the ethylesters of 3‐ethyl‐3‐pentenoic acid.It was found that for both isomers 5Jtransh.all. (homoallylic coupling) is more important than 5Jcish.all. while to the contrary 4Jtransall. (allylic c.) <4Jcisall.. Some other possible criteria for cis‐trans assignations are discussed. The conclusions are corroborated by the spectrum of the isomeric 3‐ethyl‐2‐pentenoate (C).
Burning Velocity in Mixtures of Cyanogen or Hydrogen Cyanide With Oxygen
Authors: Ailliet M. , van Tiggelen A. 
Published: September 2010

AbstractBurning velocity, flame temperature and thickness of the reaction zone have been measured in different cyanogen/oxygen/nitrogen and hydrogen cyanide/oxygen/ nitrogen mixtures.Some measurements have been made also on C2N2/O2/N2 mixtures with addition of hydrogen. Kinetical parameters have been derived: activation energy and reaction order. A kinetical mechanism has been proposed which is based on observations made by others in some studies using the technique of flash photolysis.
Oxydation En Phase Liquide Du 2,3‐Diméthylbutane
Authors: Rouchaud J. , Lutète B. 
Published: September 2010

AbstractHigh yield in acetic acid were obtained in the by oxygen liquid‐phase oxidation of 2,3‐dimethylbutane at 160°C., under 25 atm, and catalyzed by 0.64 wt% manganese. The kinetic behaviour of the products formed clears up the mechanism of oxidation. The high reactivity of the tertiary hydrogen atoms relatively to the primary explains the distribution of products. Acetone is highly reactive toward peroxidic radicals. However, its transformation into acetic acid is easily performed only when its oxidation is coupled with that of an hydrocarbon. The initiating effect is interpreted by the theory of the degenerately banched chain reactions.
The Mixed Complexes of Ni(II) in Aqueous Solutions Containing Ethylenediamine and β‐Alanine
Authors: van Poucke L. C. , Herman M. A. 
Published: September 2010

AbstractThe mixed complexes between Ni(II), ethylenediamine (A) and the β‐alaninate ion (B) are studied in 0.5 M K.NO3 at 25 °C. The existence of NiAB+ and NiA2B+ is proved and the stability constants of these complexes are given. The visible and near‐infrared spectrum of each species is reported and briefly discussed.
Base‐Catalysed Prototropic Isomerization IV. Isomerization of Conjugated Diynes on a Basic Catalyst. The Mechanism of the Base‐Catalysed Isomerization of Triple‐Bonds.
Authors: Hubert A. J. , Anciaux A. J. 
Published: September 2010

AbstractThe base‐catalysed isomerization of substituted 1,8‐diphenylocta‐3,5‐diynes has been studied. The reaction is strongly influenced by steric effects. These results help to understand the mechanism of the base‐catalysed isomerization of acetylenes which is discussed in connection with these novel observations.
Configuration Électronique Du Cation Molybdyle Chélaté Par Des Azoïques
Authors: Rouchaud J. , De Pauw M. 
Published: September 2010

AbstractSeveral chelates of the MoO2++ cation with azoic compounds have been synthesized. The corresponding peroxo compounds were obtained by reaction with H2O2. The visible absorption spectra show that the metalisation of the azoics reduces their molar extinction coefficients but does not alter significantly the wavelengths corresponding to the maximum of the absorption bands. The chelates have magnetic susceptibilities corresponding from 0 to 3 unpaired electrons. The physical properties of the chelates show the strong influence of the ligand field on the electronic configuration of the cation.
Catalyse De L'oxydation Du Propylène En Phase Liquide
Authors: Rouchaud J. , De Pauw M. 
Published: September 2010

AbstractPropylene dissolved in benzene (propylene/benzene = 0.63 g/g) has been oxidised in the liquid phase by molecular oxygen at 150 °C., under a total pressure of 45 atm. Conversion was limited to 7.5%. Several azoic chelates of the MoO2++ cation were used as catalyst. They catalyse the oxidation toward the formation of high yield in epoxypropane. One of them leads to a selectivity of 70% in epoxypropane, when the concentration of molybdenum is 3.10−4 cation g/kg of the mixture benzene‐propylene. There is a nonaccidental relationship between the magnetic susceptibilities of the molybdyl chelates and of their peroxo derivatives, and the selectivities in epoxypropane. That relationship is interpreted by the molecular orbital theory of metal‐ligand bonding.
Un Disaccharide Nouveau Extrait De La Farine De Manioc I. Établissement De La Formule De Structure
Authors: Jadot J. , Maghuin‐Rogister G. 
Published: September 2010

AbstractCe disaccharide nouveau, extrait du résidu de fermentation alcoolique d'un hydrolysat de farine de manioc, est constitue de deux molécules de D‐glucose unies par une liaison 1‐5 α. La structure a été déterminée par oxydation à L'acide periodique et par comparaison des propriétés de ses dérivés avec les propriétés des dérivés correspondants de disaccharides connus.
The Influence of Certain Nuclear p‐Substituents on the Kinetics of N‐Nitrosation and Diazotisation of Aniline
Authors: Aboul‐Seoud A. , Ahmad Moustafa 
Published: September 2010

AbstractThe specific reaction rates for the chloride‐catalysed diazotisation of aniline and p‐toluidine were combined with equilibrium data on the proton ionisation of the anilinium and p‐toluidinium ions, and on the hydrolysis of nitrosyl chloride. The specific reaction rates were calculated for the N‐nitrosation of the free amines, which is the rate‐determining stage in the diazotisation of the amines, under the present conditions. ΔG≠, ΔH≠, ΔS≠, and E were determined for this rate‐determining stage. These values were compared with the corresponding values for p‐chloroaniline. The influence of the substituents on the rates of the N‐nitrosation of these amines was discussed.
Sélectivité Catalytique Dans L'oxydation du P‐xylène
Authors: Rouchaud J. , Sondengam L. 
Published: September 2010

AbstractP‐Xylene (1.9 moles/liter, initially) dissolved in acetic acid has been oxidised by oxygen at 165deg;C (total pressure: 32 atm; partial pressure of oxygen: 25 atm). The oxidation was catalysed by bromine or by the cobalt naphthenate, or by a mixture of the two catalysts. The conversion of p‐xylene was 50%. The distribution of the main products (p‐toluic and terephthalic acids) during oxidation corresponds to the consecutive mechanism: p‐xylene →(1) p‐toluic acid →(2) terephthalic acid. Bromine and cobalt, used separately as catalysts, activate the two steps with the same intensity. The catalytic mixture of bromine with cobalt accelerates the second step much more intensively than the first one.
Physico‐Chemical Properties of Acid Saponins Surface Adsorption of Sapoalbin
Authors: Vochten R. , Joos P. , Ruyssen R. 
Published: September 2010

AbstractHet minimum in de oppervlaktespanningskoncentratiekurve werd met de betrekking van Gibbs kwantitatief geïnterpreteerd. Berekeningen werden uitgevoerd waarbij gepoogd werd de adsorptie in funktie van de pH te beschrijven. Bij de genine vrije sapoalbine ligt de adsorptie ongeveer 40% hoger dan bij de genine bevattende saponine. In funktie van de pH werd eveneens de adsorptie nagegaan enerzijds door toepassing van de betrekking van Gibbs en anderzijds door de rechtstreekse en dynamische methode. De berekende adsorptiewaarden volgens Gibbs stemmen niet volledig overeen met deze van de rechtstreekse metingen. Wegens de grote tijdfunkties blijft het nochtans een open vraag of door extrapolatie van deze rechtstreekse metingen de evenwichtsadsorptie kan gevonden worden. Door de aanwezigheid van zouten in een relatief hoge koncentratie (KNO3 0.1 M) werd een verhoging in de adsorptie waargenomen. Een eventuele verklaring zou men kunnen zoeken in de afschermende werking van de ionen op de elektrostatische repulsie.
Influence de la Température sur l'oxydation du Propylène Liquide
Authors: Rouchaud J. , Karangua A. 
Published: September 2010

AbstractPropylene dissolved in benzene has been oxidised by oxygen under a partial pressure of 12 atm, between 130 and 180 deg;C and with or without catalytic amounts of a soluble salt of MoO2++. The products result from the two competitive oxidation steps: magnified imageThe difference between the energies of activation relative to the addition and substitution, EA–S, is constant for the uncatalysed oxidation and amounts to + 6,3 kcal/mole. There is no constant EA–S for the catalysed oxidation. The results show that, in this case, the products arise from two simultaneous mechanisms: that corresponding to the uncatalysed oxidation and the one issuing from the catalytic cycle in which the peroxidic organic intermediates transform the catalyst in a peroxo compound; the last is a selective epoxidising agent of the olefinic bond.
Indole Alkaloids. XVII. Five Dihydroindole Alkaloids from Aspidosperma Verbascifolium
Authors: Braekman J. C. , Hootele C. , van Moorleghem C. , Kaisin M. , Pecher J. , Antonaccio L. D. , Gilbert B. 
Published: September 2010

AbstractA study of Aspidosperma verbascifolium has led to the isolation of four known dihydroindole alkaloids: kopsanone [I], kopsanol [II], 3'‐epikopsanol [III], 10‐oxo‐3'‐epikopsanol [IV] and a new natural product: Nα‐formylkopsanol [VII].