bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Transitions in Monolayers. Effect of a Second Component on the Transition Pressures
Authors: Joos P. 
Published: September 2010

AbstractPhase transitions in monolayers are divided into two groups regarding if a flat part in the π‐A curve occurs or only a knikpoint. This distinction is related to the miscibility or immiscibility of the two modifications in the monolayer. Phase transition were compared with monolayer collapse. Upon compression the molecular area decreases till the molecules are highest packed, but instead of collapse by further compression, the molecules undergo a reorientation to a smaller limiting molecular area.The effect of a second component on the transition pressure was examined theoretically and the corresponding equations derived, starting from the chemical potential in the monolayer as elaborated by Defay et al. The transition pressure depends on the amount of the second component added to the system and is in disagreement with the Goodrich method. The effect of cholesterol on the phase transition in a stearic and myristic acid and ethylpalmitate monolayer was examined. When the two modifications are immiscible (myristic acid and ethylpalmitate) by addition of cholesterol the phase transition disappears and causes a condension of the expanded monolayer. In the case of stearic acid (miscible modifications) addition of cholesterol yields no appreciable difference in the surface pressure at the transition point. For this system the collapse pressure shows anomalities.
NMR‐Experiments on Acetals: XXIII The Ring Shape of m‐Dioxanes, m‐Dithianes and m‐Thioxanes
Authors: Gelan J. , Swaelens G. , Anteunis M. 
Published: September 2010

AbstractIt is shown that the criterion of Lambert (allowing the description of ring shape) and the recent extension by Buys (allowing the calculation of torsion angles of parts of the ring) can be applied to unequal‐populated conformational pairs and to anancomeric systems. The results so obtained for m‐dioxanes, m‐dithianes, and m‐thioxanes are discussed in the light of the pecularities of these ring systems.
Étude des Réctions de Substitution Dans la Série des Thiénopyridines
Authors: Eloy F. , Deryckere A. 
Published: September 2010

AbstractA partir de la thiéno[3,2‐clpyridone et de son isomère [2,3‐c], on a synthétisé des thiénopyridines contenant des substituants fixés sur les noyaux de la pyridine et du thiophène. La position des substituants a été vérifiée par l'étude des spectres RMN.
Synthèse des Acides O.Acétyl et O. Benzoylthiophènecarboxyliques et de Leurs Chlorures D'Acide et Esters
Authors: Pirson P. , Schonne A. , Christiaens L. 
Published: September 2010

AbstractThe unambiguous synthesis of five new o. benzoyl and o.acetylthiophenecarboxylic acids and simple derivatives (acid chlorides and esters) is reported (I‐II: table II). These o. ketoacids might present the ring‐chain tautomerism like o. formylacids. I. R.‐N. M. R. spectroscopy and X. ray diffraction have been used to determine the positions of the substituent groups and the structure of these compounds. The physical results will be subsequently published.
Étude de Complexes Moléculaires: II. La Conductivité Électrique du Complexe de la Phénothiazine Avec le p‐chloranile
Authors: Barigand[1] M. , Tondeur J. J. , Országh J. 
Published: September 2010

AbstractThe d. c. conductance of the solid complex obtained by melting stoechiometric amounts of phenothiazine and p‐chloranil is measured. The order of magnitude and the dependence of the conductivity from the temperature show that this complex behaves like a semiconductor. The study of the influence of the granulometry, the nature and the pressure of the atmosphere surrounding the sample permits to conclude that the conduction occurs mainly by a superficial mechanism.
Contribution á L'Étude des Arséniures de Fer, Cobalt et Nickel
Authors: Naud J. , Breckpot R. 
Published: September 2010

AbstractThe stable phases in the systems FeAs, CoAs and NiAs obtainable by thermal synthesis and by precipitation with arsine have been examined by X‐ray diffraction and their electrochemical and thermodynamic behaviour compared.Precipitation of the compounds with Me/As ratio near to one is accompanied by hydrogen evolution whilst the metal rich derivatives obtainable only with nickel (Ni11As8, Ni5x As2) are the result of an oxydo‐reduction reaction function of solution pH with as second member of the couple AsO.Cathodic polarisation leads to metal rich compounds in the case of iron (Fe2As) and nickel (Ni11, As8 and Ni5As2). In all cases excess metal is bound to the substrate in an amorphous non ferromagnetic form.
Évaluation des Potentiels D'Ionisation et des Électroaffinités des Hydrocarbures Saturés et Insaturés et de Quelques Radicaux au Moyen du Modèle de L'Électron libre (F.E.M.)
Authors: Jannes G. , Puttemans J. P. 
Published: September 2010

AbstractThis study is based on the existing linear relationship between the energy of the highest occupied orbital and the experimental ionization potential as well as on the linear relationship between the energy of the lowest free orbital and the electro‐affinity. The energies of these levels are deduced from F.E.M. calculations.This method yields results in the different series favourably comparable with those obtained by more sophisticated techniques. Thanks to existing experimental values, it was possible in the aromatics to evaluate unknown electroaffinities, reduction potentials as well as half‐wave potentials.
Kinetics of Oxidation of trans‐2‐Chlorocyclohexanol with Bromine
Authors: Kudesia V. P. 
Published: September 2010

AbstractThe kinetics of oxidation of ttans‐2‐chlorocyclohexanol with bromine has been studied at 40°C. The reaction has been found to obey second order kinetics, with first order dependence on each reactant. The thermodynamic activation parameters are reported. A cyclic mechanism is suggested.
Theoretical Study of Small Ring Compounds. II. Cyclopropane, Methylcyclopropane and Dimethylcyclopropanes
Authors: André Jean‐Marie , André Marie‐Claude , Leroy Georges 
Published: September 2010

AbstractOn décrit des calculs «ab initio» de la fonction d'onde de l'état fondamental du cyclopropane et de ses dérivés méthylé et diméthylés. On discute les relations entre la structure électronique et les propriétés statiques et dynamiques de ces molécules.
Differences in Solvent‐Effects on the Association of Primary, Secondary, and Tertiary Alcohols
Authors: Mullens J. , Hanssens I. , Huyskens P. 
Published: September 2010

AbstractDifferent association‐parameters of primary, secondary, and tertiary alcohols dissolved in CCl4 and C6H6 were compared with their values in cyclohexane. The parameters are the monomer‐fraction α1, the fraction of the open entities relatively to the formal number of molecules σαn, o, the average degree of association of one molecule σnw, the fraction of the number of all the real entities relatively to the formal number of molecules σαn and the mean association‐constants kM of a monomer to a given entity (monomer, dimer…).The experimental methods were the determination of the partition‐coefficients of the alcohols between the organic solvent and water and the infra‐red spectrometry. This study shows that the concurrence the solvents CCl4 and C6H5 oppose to the auto‐association of the alcohols is not the same for all the alcohols. These differences in solvent‐effects lead in some cases to an inversion in the sequence of the alcohols ordered after their association‐parameters in benzene and in CCl4 relatively to this sequence in C6H12.
Ring Contraction In 1,3‐Dioxanes
Authors: Borremans F. , Anteunis M. 
Published: September 2010

AbstractRing contraction is observed during nucleophilic displacement reactions of 5‐hydroxy‐2‐methyl‐1,3‐dioxanes.Evidence is put forward that the mechanism of this contraction is not similar to that of the concerted ring contractions known for analogous pyrane‐ and/or 1,3‐dithiane systems.A reaction path concordant with experimental facts is advanced.
Preparation of 4,6‐Methyl, Alkyl‐1,3‐Diselenanes; 4,6‐Methyl, Alkyl‐1,3‐Thiaselenanes and 4,6‐Methyl, Alkyl‐Oxaselenanes
Authors: Geens A. , Anteunis M. 
Published: September 2010

AbstractA general method for the preparation of 4,6‐disubstituted 1,3‐diselenanes and corresponding thiaselenanes and oxaselenanes is reported starting from appropriate (secondary) β‐diols. The corresponding mono‐ or di‐mesylates (alt. β‐dibromides) are treated with sodium selenocyanate and/or sodium sulfocyanate in HMPT below 80°C. The resulting alkyl β‐(di)seleno(sulfo) cyanates are subsequently reduced with sodium in liquid ammonia, followed by formalation in strong acidic medium. The resulting different positional and geometric isomers could not be completely separated by GC. Small amounts of accompanying 1,2‐diselenolanes may disturb class‐separation, but they can be removed after LAH treatment of the reaction mixture.
Hétérocycles Tellures. II. La Telluroflavanone
Authors: Piette J.‐L. , Renson M. 
Published: September 2010

AbstractL'o‐méthyltelluroacétophénone est préparée par réaction du lithium sur l'(o‐iodo phényl)‐2 méthyl‐2 dioxolane‐1,3, suivie successivement de la condensation avec le tellure et l'Iodure de méthyle.La condensation de cette substance avec le benzaldéhyde conduit au (cinnamoyl‐2 phényl) méthyltellurure qui peut être cyclisé en telluroflavanone. Le produit principal de la réaction est cependant le (cinnamoyl‐2 phényl) bromure de tellurényle.
The Isomerization Mechanism of Humulone
Authors: Verzele M. , van Boven M. 
Published: September 2010

AbstractThe first step in the isomerization of humulone in mildly acid or alkaline media is the formation of a mono anion. This is followed by stereospecific ketonization and only then by the ring contraction, producing trans and cis isohumulone, in a 32/68 ratio. In strong alkaline medium the reaction proceeds over a dianion form and the isomer ratio is then 50/50.
Oxygen‐inhibited photochlorination of 1,2‐dichloroethane
Authors: Bertrand L. , Bizongwako J. , Huybrechts G. , Olbregts J. 
Published: September 2010

AbstractThe oxygen‐inhibited photochlorination of 1,2‐dichloroethane has been studied in the gas‐phase between 321 and 489,5°K. The following rate constants have been estimated:magnified imageThese results are compared to those observed for the reactions of C2H6, C2HCl5, C2HCl3 and C2Cl4.
Sélénazolidines IV. Sélénazolidines Dérivées de la Séléno Cystéine et de la Sélénopenicillamine
Authors: Draguet C. , Renson M. 
Published: September 2010

AbstractNous décrivons la synthèse de quelques carboxy‐4 sélénazolidines, issues de la sélénocystéine et de la sélénopénicillamine.
Mechanism of the Iodide‐Ion Induced Dehalogenation of Substituted Stilbene Dibromides
Authors: Nasielski J. , Guiette‐Limbourg V. 
Published: September 2010

AbstractSymmetrically ring‐substituted stilbene meso dibromides are dehalogenated by iodide ions in acetone with rates depending on the substituent. The HAMMETT pσ correlation for this E2 concerted elimination is however a curve showing a well‐defined minimum (fig. 1) rather than a straight line. This behaviour is ascribed to the very high polarizability of the transition state.
Radiation chemistry of 1‐chloropentane in the solid phase I. Influence of the dose
Authors: Ceulemans J. , Claes P. 
Published: September 2010

AbstractThe influence of the dose on the yields of the radiolysis products of 1‐chloropentane, irradiated in the solid phase by gamma rays of a 60Co source, has been investigated. We observed a decrease of the yield of hydrogen, hydrogen chloride, the pentenes, the decanes and of certain chlorodecanes and an increase of the yield of pentane and of certain dichloropentanes and dichlorodecanes in function of the dose. Some of these dose effects cannot be explained by a purely radicalar mechanism, but they may be explained by a mechanism, which includes radicalar and ionic reactions. It must therefore be concluded that ionic species play an important role in the radiolysis of solid 1‐chloropentane. The effects, invoked to explain the influence of the dose on the G yields, are reactions of active species with unsaturates formed during the radiolysis or with trapped radicals.
Alcaloïdes Pipéridiniques III. Nouveaux Alcaloïdes du Prosopis Africana (Guill. et Perr.) Taub.: Isoprosopinines A et B, Prosophylline, Prosafrine Et Prosafrinine [1]
Authors: Khuong‐Huu Qui , Ratle Georges , Monseur Xavier , Goutarel Robert 
Published: September 2010

AbstractThe structures of five new alkaloids have been established: the isoprosopinines A and B, 1 and 2 are homogeneous mixture: isoprosopinine A is (2R, 3S, 6R) 2‐hydroxymethyl 3‐hydroxy 6‐dodecyl 7°‐keto piperidine and isoprosopinine B is (2R, 3S, 6R) 2‐hydroxymethyl 3‐hydroxy 6‐dodecyl 8°‐keto piperidine.Prosophylline 4 is d 2‐hydroxymethyl 3‐hydroxyl 6‐dodecyl 10°‐keto piperidine, prosafrine 9 is (2R, 3R, 6S) 2‐methyl 3‐hydroxy 6‐dodecyl 10°‐hydroxy piperidine and prosafrinine 11, is (2R, 3R, 6S) 2‐methyl 3‐hydroxy 6‐dodecyl 10°‐keto piperidine.
Étude de Complexes Accepteur‐Donneur par Spectrométrie Infrarouge III. Influence de la Nature du Solvant sur les Complexes Formés Entre L'Acétophénone ET SbCl3 (suite)
Authors: Ère‐Zur Nedden G. Lecl 
Published: September 2010

AbstractInfrared intensity measurements of the free C = 0 band have been used to investigate the complex formation between antimony trichloride and acetophenone in carbon disulfide, benzene and trichlorethylene. The dissociation constants of the acceptor‐donor complexes with a 1:1 stoichiometry are compared with different parameters of the solvents.
Constituents of Peppers II. Piperinic Acid and its Isomers
Authors: Cleyn R. De , Verzele A. 
Published: September 2010

AbstractThe four isomers piperinic, chavicinic, isopiperinic and isochavicinic acid are obtained by irradiation at λ = 350 nm of a methanolic solution of piperinic acid. They are separated by counter current distribution. Their spectral characteristics are discussed.
Structure Cristalline de la 4‐Nitro‐4′‐Méthoxy‐N‐Benzylidène‐Aniline
Authors: Meunier‐Piret J. , Piret P. , Germain G. , Meerssche M. Van 
Published: September 2010

AbstractThe crystal structure of 4‐nitro‐4′‐methoxy‐benzalaniline has been determined by X‐ray diffraction. Space group P21/c, a =12.888, b = 7.098, c= 14.066 Å, β = 102.820°; Z = 4. Distance N = C: 1.235 Å, angles NCC and CNC: 124° and 117°. Angle between the mean planes of the phenyl groups: 52.5°
Isomérie Anneau‐Chaïne Ouverte. Obtention de la Diphényl‐2,2 Benzoxathianne‐1,3 One‐4
Authors: Renson M. 
Published: September 2010

AbstractL'action du diphénylcadmium sur le chlorure de benzoylthiosalicyloyle donne la diphényl‐2,2 benzoxathianne‐1,3 one‐4. Nous avons préparé cette substance par une seconde méthode non ambiguë. Elle est identique à celle obtenue récemment par Dittmer et Whitman suivant une méthode totalement différente.
Essais de Chloration Dirigée XVII. Photochlorations D'Acétates et de Chlorures D'alkyles en Compétition Avec le Toluène[1]
Authors: Soumillion J. Ph. , Bruylants A. , De Wolf B. , Cuvelier B. 
Published: September 2010

AbstractPhotochlorinations of alkyl acetates (R‐OCOCH3 with R = n‐propyl, n‐butyl, n‐amyl, i‐butyle) and chloroalcanes (R‐Cl with R = n‐amyl, n‐hexyl) were performed in competition with toluene.With the aid of properly modified TAFT's equation, the relative reactivities of hydrogen atoms were correlated with substituent effects (inductive and mesomeric effects, hyperconjugation).The authors observed an inversion in the order of reactivities on the terminal positions of 1‐chlorohexane. They attributed this phenomenon to the aliphatic chain's crumpling of the molecule, They also discuss the problem of the transmission of inductive effects across the aliphatic chain of the molecules.
Amino Steroids ‐ Conanine and Heteroconanine Derivatives
Authors: van De Woude G. , van Hove L. 
Published: September 2010

AbstractConanine (IIh) and heteroconanine (IIIh) were obtained as the ultimate products of two reaction sequences starting from 3β‐hydroxy‐Sα.‐pregnan‐20‐one oxime and involving the preparation of epimeric 20‐amino steroids.Comparison of physical properties of these epimer pairs shows that at least qualitative effects can be correlated with the configuration at C‐20 of epimer 20‐amino steroids.
Tautomérie Dans la Série des Pyrazolinones. III. Influence de la Position et de la Nature des Substituants sur L'Équilibre Prototropique des Pyrazoline‐5‐ones N1 Substituées
Authors: Maquestiau A. , van Haverbeke Y. , Jacquerye R. 
Published: September 2010

AbstractThe influence of substituents on N1 substituted pyrazolin‐5‐ones on tautomeric equilibrium has been carried out.In position 4, the isomer CH is strongly displaced towards NH and equilibrium is shifted by electrowithdrawing substituents to the pyrazol‐5‐ol form.An explanation for concentration effect observed in a series of pyrazolinone molecules is proposed.
Mesure Du Potentiel Standard Du Couple Pu(IV)/Pu(III) Dans L'eutectique LiCl‐KCl Entre 400 Et 500°C
Authors: Martinot L. 
Published: September 2010

AbstractWe have measured the standard potential of the system Pu(IV)/Pu(III) in a LiCl‐KCl molten eutectic.The cell used was the following one: magnified image A comparison with previous standard potential determinations of uranium and neptunium in the same eutectic is reported.
N‐alkylation of 1, 4‐dihydropyridine derivatives
Authors: Dommisse R. A. , Alderweireldt F. C. 
Published: September 2010

AbstractA series of 1‐alkyl‐2, 6‐dimethyl‐3, 5‐diethoxycarbonyl‐4‐aryl‐1, 4‐dihydropyridines have been synthesised by the reaction of the corresponding 1, 4‐dihydro‐pyridines with consecutively sodium hydride and alkyl halides.
Formal Properties of Stereoisomerizations of Pentacoordinate Complexes. II. Particular Ligand Partitions
Authors: Brocas J. , Willem R. 
Published: September 2010

AbstractIn this paper, we present the solution of the rate equation of all the possible isomerization modes of a trigonal bipyramidal pentacoordinate complex in which less than five ligands are different. The possible applications of this model are discussed.
The Role of Charge‐Transfer Complexes in the Reaction of Tertiary Amines with Tetrachlorophthalic Anhydride
Authors: Nagy J. B. , Nagy O. B. , Bruylants A. 
Published: September 2010

AbstractTetrachlorophthalic anhydride reacts readily with tertiary amines in non‐hydroxylic organic media to give a highly hygroscopic betaïne‐like product formed by the opening of the anhydride ring. The structure of this product is proven by U. V., I. R. and N. M. R. data. The n‐π charge‐transfer complexes formed between the anhydride and the amines are detected.The solvent effect study suggests that these charge‐transfer complexes might be real intermediates on the reaction path.In the light of the results obtained a general scheme is proposed for nucleophilic reactions of the carbonyl, group. A solvent parameter is also proposed to represent the π‐donor ability of aromatic molecules.
Acrylamidines and Polyacrylamidines. Part 2. A New Synthesis of N‐Substituted Acrylamidines
Authors: Fuks R. 
Published: September 2010

AbstractN‐substituted acrylamidines, a new class of acrylic monomers have been obtained recently(1) from acrylonitrile, an alkyl halide, a Lewis acid and an amine.I would like to report on a new synthesis starting from β‐chloropropionitrile 1 following the general method previously published(2).The N‐alkylation of 1 with isopropyl chloride in the presence of ferric chloride gives N‐isopropyl‐β‐chloropropionitrilium tetrachloroferrat 2. Its aminolysis with aniline provides the amidinium salt 3 whose neutralization furnishes the N‐isopropyl‐N′‐phenyl‐β‐chloropropionamidine 4. This rearranges on standing at room temperature within an hour or two into the hydrochloride of N‐isopropyl‐N′‐phenylacrylamidine 5 identical with the compound prepared from acrylonitrile (1).
Conformational Aspects of Some Methoxysubstituted Hexacarbocyclic Derivatives
Authors: Anteunis M. , Geens A. , van Cauwenberghe And R. 
Published: September 2010

AbstractThe quantitative conformational behaviour of a methoxy group is studied in a series of hexacarbocyclic compounds I, II, III and VII depicted in SCHEME 1. It is found (Table I) that the equatorial preference of that group is accentuated in polar solvents such as freon 21, propably for entropy reasons. The conformational behaviour is normal for the spiro derivative II, but in the 2‐methoxy cis‐decalane a complex situation arises from additional no‐bond interactions in the decalane skeleton itself. Some derivatives in which the conformational behaviour of a hydroxy group could be weighted against that of a methoxy group were also investigated, and show results in accordance with expectations.Finally the barrier for ring reversal between equienergetic conformer possessing various types of methoxy substitutions were studied by different methods (Table III). The unreliability in the calculation of ΔH∦ and ΔS∦ was noted.
Statistical Evaluation of Two Air Samplers and of The activation Analysis of Aerosols
Authors: Heindryckx R. , Dams R. 
Published: September 2010

AbstractUsing two types of high volume air sampling systems the reproducibility of the sampling procedure, the homogeneity of the collected aerosols over the filter and the standard deviation of the analyses are evaluated. Aerosols are collected simultaneously with 4 identical samplers on one location. The 4 filters are quartered and the concentrations of 11 elements are determined in triplicate on all 16 quarters by instrumental neutron activation analysis. A variance and a propagation of errors analysis are performed.
Étude R. P. E. De La Recombinaison Des Radicaux Pièges Dans Quelques Solides Organiques Polymorphes Irradies A 77°k
Authors: Mauer D. , Tilquin B. , Claes P. 
Published: September 2010

AbstractThe recombination temperature (TR) of radicals trapped in σ‐irradiated organic solids showing phase transitions has been determined. A comparison is made between TR and the entropy of transition. It is concluded that radical diffusion is due to molecular reorganization during phase transition.
On The Occurrence of Fries Type Reactions in Polyphosphoric Acid. Synthesis of 2‐alkyl Substituted 4‐Chromanones from Phenols and α, β‐Unsaturated Carboxylic Acids
Authors: van De Sande C. , Vandewalle M. 
Published: September 2010

AbstractThe condensation of phenols and α, β‐unsaturated carboxylic acids in polyphosphoric acid is investigated. Spectroscopic data are included.
Les Nitrates Basiques Mixtes de Zinc et de Nickel
Authors: Mannoorettonnil M. , Glibert J. 
Published: September 2010

AbstractThe basic nitrates of zinc and nickel precipitated at 20°C have the compositions Zn5(OH)8(NO3)2·2 H2O and 4 Ni(OH)2·Ni(OH)0,75 (NO3)I, 25·n H2O· Obtention of this monoclinic zinc salt is preceeded by the formation of a double layered hexagonal compound. At 75°C, ZnO and Ni(OH)2 are formed.In mixed (Zn, Ni)‐solutions, at 20°C and for a reaction time of about I hour, the solid solution Zn5‐xNix (OH)8(NO3)2·2 H2 2O (I) is obtained in the zinc rich region. The passage to the monoclinic system is inhibited with the increase in the percentage of nickel, resulting in the precipitation of the double layered basic nitrate 4 ZnI‐x Nix (OH)2· Ni(NO3)2·n H2O (II) from 20 to 50 at. · Ni.A transition zone separates this salt from the basic nitrate of nickel in which the maximum solubility of zinc is about 10% at.At 75°C, ZnI‐xNixO (xmax· = 0, 4 at. %Ni) and NiI‐yZny(OH)2 (ymax · = 26 at. %Zn) are respectively formed. A demixtion zone separates the oxide from the double layered basic nitrate (II).
The photoproduction of dihydroxotetracyano‐cobaltate(III)
Authors: Viaene L. , D'Olieslager J. , De Jaegere S. 
Published: September 2010

AbstractThe photochemical substitution of CN− by OH− in Co(CN)5OH3‐ yields either cis‐ or trans‐ Co(CN)4 (OH)3‐2 depending on the temperature. At 25°C a quantum yield of 0.093 was calculated. The thermal anation of cis‐Co (CN)4 (OH)3‐2 with CN− was found to follow second order kinetics with a rate constant k2 = 1.2.10−2 l. mole−1 sec−1 at 25°C.