bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescence Solvent Shifts and Singlet Excited State pK's of Indole Derivatives
Authors: Donckt E. Vander 
Published: September 2010

AbstractFluorescence shifts of indole derivatives in aprotic solvents can be understood on the basis of a general dielectric effect. In protic media as water and ethanol, hydrogen bonds are formed between indole acting as a base and the solvent as an acid. It is shown that the basicity increase in the S1 state of indole derivatives is consistent with this view.
Communication to the Editor. A New Synthetic Route to Vic‐Triazoles
Authors: L'Abbé G. , Ykman P. , Smets G. 
Published: September 2010

AbstractWe wish to report our discovery and mechanistic characterization of a reaction in which an ester phoshorus ylid I is transformed by acyl azides II into 1‐acyl‐vic‐triazoles IV.
Essais de Chloration Dirigée. X. Photochloration Directe D'acétates D'Alcoyles [1]
Authors: Ph. Soumillion J. , Bruylants A. 
Published: September 2010

AbstractA series of alkylacetates, R–COOCH3, with R‐ = n‐propyl, isopropyl, n‐butyl, isobutyl and amyl, was chlorinated photochemically in order to obtain mono‐substituted products. Analysis of reaction samples was made by gas‐liquid chromatography and identification of monochlorinated derivatives was performed by reference synthesis and N.M.R. spectroscopy.Experimental results showed an important activation for positions of the molecules substituted by electrodonor groups like methyl. On the contrary, positions substituted by electron withdrawing functions, like the acetoxy group, were desactivated. These results were correlated by a reactivity‐structure relationship, showing the separation between inductive and resonance effects. The equation used was: magnified image with p* = ‐0.843 and h = +0.034.In view of the fact that the polar effect constants (σ*) for acetoxy and acetoxy‐methylene groups were not known, these constants were determined: magnified image.The acetoxy sigma constant was considered as the sum of two terms: inductive (σ*−1) and mesomeric (σ*+M).
Organophosphorus Chemistry. Part I. On The Synthesis of Arylphosphines and Arylphosphine Halides
Authors: De Ketelaere R. , Muylle E. , Vanermen W. , Claeys E. , Van Kelen G. P. Der 
Published: September 2010

AbstractDetailed and improved procedures for the preparation of (4‐FC6H4)nPCl3‐n and (3‐FC6H4)nPCl3‐n are presented. The identity and the purity of the substances were checked by I.R., n.m.r. (1H, 19F, and 31P) and mass spectrometry.
Solvent Shift Criteria in NMR. The Assignment of Cis‐Trans Isomers of Glycidic Esters
Authors: Vandenbroucke W. , Anteunis M. , De Bruyn A. 
Published: September 2010

AbstractSolvent shift criteria can be used for the cis‐trans structural assignment in glycidic esters. Protons of substituents which are trans to the alkoxycarbonylgroup are shifted towards higher field in benzene than in carbon tetrachloride. Definitive proof of the structures were obtained by Nuclear Overhauser Effect experiments.
The Friedel‐Crafts Acylation Reaction. VII. Kinetic Analysis of the Aluminum Chloride Catalysed Reaction of Various Substituted Benzoyl Chlorides with Some Benzene Derivatives the Behaviour of the Benzoylating Complex
Authors: Hoornaert G. , Slootmaekers P. J. 
Published: September 2010

AbstractCe travail traite de l'acylation de quelques hydrocarbures aromatiques, présents en excès, par des chlorures de benzoyle substitués. Surtout le comportement du complexe benzoylant en ce qui concerne son ordre courant et initial est étudié.II est vérifié que l'augmentation de k1 app. en fonction de la concentration initiale du complexe est due à l'action compétitive d'une, sinon deux, réactions d'ordre formel égal à deux par rapport au complexe réactionnel. En nous basant sur les valeurs du poids moléculaire de tels complexes dans plusieurs solvants, nous avons proposé l'intervention partielle d'une forme dimère du complexe. Une voie de réaction, par laquelle un intermédiaire, constitué d'une molécule de l'hydro‐carbure actif et d'une molécule du complexe benzoylant, réagit avec une deuxième molécule du complexe benzoylant dans l'étape limitative, peut également être admise.
Synthèse et Étude de la Structure Moléculaire de la 2‐(3'‐Pyridyl)‐Pyrido[2,3d]Pyrimidine
Authors: Osselaere J. P. , Dejardin J. V. , Dejardin‐Duchêne M. 
Published: September 2010

AbstractNicotinamide was treated by ammonium sulphamate, and 2‐(3'‐pyridyl)‐pyrido‐[2,3d]pyrimidine was isolated as unexpected product with a good yield. The molecular structure of this compound was investigated by means of Infrared, NMR and Mass spectrometry. The results obtained from this study allowed to establish the given formula.
Établissement de la Formule de Structure d'un Nouvel Acide Aminé Soufré de Xerocomus Subtomentosus
Authors: Jadot J. , Casimir J. , Warin R. 
Published: September 2010

AbstractLe nouvel acide aminé soufré isolé du champignon Xerocomus Subtomentosus est caractérisé par la formule brute C8H10N2O4S. Des études analytiques et des réactions de dégradations ont montré qu'il s'agissait d'un acide α‐aminé bibasique dérivant du thiazole. II s'agit de l'acide α‐amino γ‐(carboxy‐4 thiazolyl‐2) butyrique. La synthèse de cette, substance corrobore la structure chimique proposée du composé naturel.
NMR‐Experiments on Acetals. XVI. Low Temperature Experiments and Conformational Data on 4‐Substituted CIS‐1,3‐Dioxadecalanes
Authors: Swaelens G. , Anteunis M. 
Published: September 2010

AbstractIn contrast to 4,6‐disubstituted‐1,3‐dioxanes it is possible to obtain at low temperature for 4‐Ra ⇌ e‐cis‐1,3‐dioxadecalanes(†) (I ⇌ I0) the NMR spectra of the individual conformers. Direct integration of suitable regions in the spectrum gave the composition of conformers. An attempt was made to estimate the ΔH° values of R‐groups in 1,3‐dioxanes by means of à priori calculations, based on assumed interactions. The ΔH° between O‐inside and O‐outside‐1,3‐dioxadecalane (I ⇌ I0 R = H) is evaluated to be 2.62 kcal/mole.
Méthode générale de synthèse de thio‐1 et séléno‐1 coumarines par cyclisation d'acides O‐méthylthio et O‐méthylsélénocinnamiques
Authors: Ruwet A. , Renson M. 
Published: September 2010

AbstractWe synthetize for the first time the seleno‐1 coumarin, a new heterocyclic compound [1]. The chemistry of the thiocoumarins is not very satisfactory. It is possible now to accede easily to thio‐1 coumarins as well as seleno‐1 coumarins by a general method giving good yields: the cyclization of o‐methylthio and o‐methylseleno‐cinnamic acids. About fifty examples are given. The coumarins are also available from o‐methoxycinnamic acids in similar conditions. We show how we arrive to this way and we discuss the mechanism of the cyclization.
Propriétés physico‐chimiques de composés caractère aromatique. potentiels de demi‐onde de réduction polarographique d'aldéhydes polycycliques aromatiques
Authors: Anthoine G. , Nasielski J. , Wilmet‐Devos B. 
Published: September 2010

AbstractA series of ten aromatic aldehydes have been reduced at the dropping mercury electrode in dry D.M.F. Oscillopolarography has shown (table III) that the first wave is reversible at 20 Hz. The half‐wave potentials correlate reasonably well (table IV) with the energy of the lowest vacant M.O.
Étude théorique des systèmes hétéroatomiques conjugués. III. les composés carbonylés
Authors: Aussems C. , Jaspers S. , Leroy G. , van Remoortere F. 
Published: September 2010

AbstractThe semi‐empirical LCAO—SCF—MO method described in previous papers is further applied to some conjugated compounds containing the carbonyl group.The theoretical results are discussed in the light of available experimental data, especially the electronic spectra and the ionization potentials.The overall agreement between calculated values and measurements is satisfactory.
Mesure du potentiel standard du couple Np(III)/Np(o) dans l'eutectique LiCl‐KCl entre 400 et 550°c
Authors: Martjnot L. , Duyckaerts G. 
Published: September 2010

AbstractWe have measured the standard potential of the system Np(III)/Np(o) in the molten LiCl—KCl eutectic.The cell used has been the following:magnified imageThe work was carried out in glove‐boxes under a pure argon atmosphere.A comparison has been made with previous standard potentials determinations of uranium and neptunium in the same eutectic.
Indole Alkaloids. XX. Isolation and Structural Elucidation of Four Minor Alkaloids from Voacanga Chalotiana Pierre Ex Stapf
Authors: Braekman J‐C. , Tirions‐Lampe M. , Pecher J. 
Published: September 2010

AbstractA further study of Voacanga chalotiana Pierre ex Stapf has led to the isolation of two known indole alkaloids: polyneuridine [2] and akuammidine [3], and of two new oxygenated derivatives of voachalotine [1]: voachalotine oxindole [4] and 21(?)‐hydroxyvoachalotine [5].
Microbiologie analytique. étude du dosage de la thymine à l'aide de streptococcus faecalis()
Authors: Rappe André 
Published: September 2010

AbstractDans le cadre de l'étude que nous avons entreprise sur le dosage microbiologique des bases puriques et pyrimidiques, nous présentons dans ce travail l'adaptation au milieu liquide du dosage de la thymine dont la réalisation en milieu solide a été précédemment décrite [4].Nous examinerons successivement la technique de l'essai, l'étude du dosage de la thymine et dérives et l'étude de la spécificité.
Détermination empirique de l'effet d'anisotropie diamagnétique exercé sur les protons aliphatiques en résonance magnétique nucléaire
Authors: Nagy O. B. , Ph. Soumillion J. , Bruylants A. 
Published: September 2010

AbstractAn empirical correlation method relating proton chemical shift to Taft σ* parameters is extended to a series of halogenated compounds. The results obtained make it possible to determine new diamagnetic anisotropy corrections for various substituents. The scope and limitation of the method are discussed.
N.M.R. Experiments on Acetals: XX [I]. Conformational Equilibrium in 5,5‐Disubstituted 1,3‐Dioxanes
Authors: Coene E. , Anteunis M. 
Published: September 2010

AbstractA number of 5, 5‐disubstituted 1,3‐dioxanes (mostly methyl, alkyl) were prepared and their PMR spectra studied at various temperatures. Conformational equilibria and thermodynamic parameters were obtained (table I), using correct [7] shift data. The results obtained with data for H‐2 hydrogens are more accurate then those for H‐4,6 hydrogens. Some ambiguity however exists concerning equilibria for 5‐Me‐5‐nalkyl‐mdioxanes and different sets of values remain possible (table III). In general however it seems that the method of calculation as previously introduced [7] gives more then satisfactory results. Accuracy seems to be very high and without correction of the shift parameters for their temperature dependance, the linearity of the total free energy differences with temperature is often very bad. Even after correction it remains bad however for 5‐Me‐5‐rBu‐1, 3‐dioxane. Some spectral features of the latter compound are discussed and it is shown that H‐4a (H‐6a) resonates at lower field then H‐4e (H‐6e).
N.M.R. Experiments on Acetals: XXI [1]. Barriers for Ring inversion in Some Geminal Substituted 1,3‐Dioxanes
Authors: Coene E. , Anteunis M. 
Published: September 2010

AbstractBarriers for ring inversion in some 5,5‐gem. substituted m. dioxanes (dialkyl‐ and spiro derivatives) were measured and compared with some 2,2‐gem. substituted derivatives. The results are compatible with a lowering of ΔG≠ when steric compression is higher in the ground state (table I). An exceptional low value is found in 5,5‐di isopropyl‐m‐dioxane (ca. 8 kcal/mole), whereas normally the geminal 5‐substitution raises the inversion barrier. Some spectral features of 5,5‐pentamethylene‐ and 5,5‐dimethyl‐2,2‐pentamethylene‐m‐dioxane are commented.
A Kinetic Study of the Diazotisation and N‐Nitrosation of The Toluidines
Authors: Aboul‐Seoud A. , Ahmad Moustafa 
Published: September 2010

AbstractThe kinetics of the chloride‐catalysed diazotisation of the toluidines were investigated. For the rate‐determining stage, which is, under the present conditions, the N‐nitrosation of the unprotonated amine by NOCl, the values of the specific reaction rate, the free energy of activation, ΔG≠, the enthalpy of activation, ΔH≠, the entropy of activation, ΔS≠, and the energy of activation, E, were determined and compared. The influence of the nuclear methyl substituent, in the different positions of the benzene ring in the aniline molecule, was interpreted in terms of electrical effects.
Spectrophotometric Study of N,N′‐bis(m‐Sulphobenzyl) Dithio‐Oxamide as a Reagent for Palladium (II)
Authors: Janssens A. A. , Herman M. A. 
Published: September 2010

AbstractThe complex formed between N, N′‐bis(m‐sulphobenzyl)dithio‐oxamide and palladium (II) can be used for the spectrophotometric determination of this metal in aqueous solution.In 6 M hydrochloric acid solution, the absorbance measurements are carried out at 432 mμ. Beer's law is obeyed over the range 0,4 to 12 μg Pd per ml and the sensitivity is 0,0076 μg per sq. cm.In buffered weak acid solution (pH 6,8) the absorbance measurements are made at 390 mμ. Beer's law is obeyed ove. the range 0,4 to 12 μg Pd per ml and the sensitivity is 0,0090 μg per sq. cm. Foreign ions interfere less in 6 M hydrochloric acid than in buffered weak acid solution.
Étude de Complexes Moléculaires I. Cinétique et Équilibre de la Réaction de la Phénothiazine Avec le p‐Chloranile dans L'acétonitrile
Authors: Barigand M. , Orszagh J. , Tondeur J. J. 
Published: September 2010

AbstractThe kinetics of the reaction phenothiazine + ρ‐chloranil is followed by spectrophotometry, in the solvent acetonitrile. The molar absorption coefficient of the green product of this reaction is calculated.As shown by the experimental results, this second order reaction leads very slowly to an equilibrium.The values of kinetic constants, equilibrium constant, activation energy and enthalpy of reaction are given.
Étude des Spectres de masse D'Une Série de Méthylalkyl Mercure
Authors: Spielmann R. , Delaunois C. 
Published: September 2010

AbstractWe have realized the synthesis of a serie of dialkylmercury compounds, where a group alkyl is always the same. The mass spectra are described and analysed. The main fragmentation observed is the lost of an alkylradical.However, we have also observed secondaries fragmentations coming from intramolecular mecanism. We have mentioned the differents states of oxydations and the probable rupture's sequences of the differents substituants fixed on the mercury. We do not observe metastable ion for this series of derivatives.
The Oxidation of N‐Substituted V‐triazole: (A Meisenheimer‐Rearrangement)
Authors: Hubert A. J. 
Published: September 2010

AbstractThe oxidation of I‐substituted v‐triazoles R‐CH2‐(N3C2HR') gives oxy derivatives R‐CH2‐O‐(N3C2HR'). They are probably formed by a Meisenheimer‐rearrangement of an N‐oxide which cannot be isolated under the conditions used for the reaction.
Essais de Chloration Dirigée: XIV. Effets de Solvant sur la Photochloration D'Hydrocarbures Arylaliphatiques(1)
Authors: Corbiau J. L. , Bruylants A. 
Published: September 2010

AbstractIn the photochlorination of arylaliphatic hydrocarbons (C6H5R; R = C2H5; n. C3H7; i. C3H7; n. C4H9; sec. C4H9; n. C5H11) substitution only takes place in the side chain, and preferentially in the α position, as was showed in the previous paper. Now, in order to make clear which effect is operative‐ either the polar effect of the substituent or a complexation effect of the aromatic nucleus of the reagent, photochlorination of the title compounds was examinated in various solvents (CCl4, aromatics and CS2). Firstly, diluting by CCl4, it was observed that relative reactivity, r. r. (a/b), of an hydrogen a versus another b, varies with the concentration and can be expressed as a linear function:

Including complexation constant K1, specific rate ka1 and relative reactivity kao/kbo at infinite dilution (whose numerical values can be calculated by means of the former formula), if R is C2H5; n. C3H7; i. C3H7; sec. C4H9, and with a more sophisticated one:

for the other terms, R = n. C4H9, n. C5H11. With benzene, selectivity is enhanced but with chlorobenzene it is depressed. Finally, the best results concerning the selectivity are obtained by photochlorination in the presence of CS2. We mention here the most interesting result of cumene (R = i. C3H7), giving up to 98% of α‐chloroisomer in the presence instead of 86% of the same in the absence of CS2.
The Thermodynamics of Ionization of Anilinium Ions in Ethanol‐Water Mixtures
Authors: van de Poel W. , Slootmaekers P. J. 
Published: September 2010

AbstractThermodynamic parameters of ionization of a number of substituted anilinium ions were measured in water and in ethanol–water mixtures at 25°C. Both the enthalpy and entropy of ionization show extreme values in a solvent mixture containing 0,90 mole fraction of water. Free energy values decrease smoothly and monotonically with increasing ethanol content of the solvent.It is shown that the solvent effect is dependent on the nature of the substituent on the anilinium ion.The results are treated in terms of the structural theory of water and of ethanol–water mixtures. Furthermore, an attempt is made to determine the value of β, the proportionality constant between ΔHext and ΔSext, which was introduced by Hepler.
L'Étude Théorique des Systèmes Périodiques: V. Les Expressions Analytiques des Intégrales Électroniques et des Bandes D'Énergie
Authors: André J. M. , Delhalle J. , Leroy G. 
Published: September 2010

AbstractOn déduit la forme explicite des intégrales électroniques dans les systèmes périodiques tridimensionnels. Dans la dernière partie, on décrit un procédé général pour obtenir une expression analytique simple des bandes d'énergie dans les cristaux.
Couches de Diffusion D'Aluminium Formées par Électrolyse sur le Nickel dans les Chlorures Fondus
Authors: de Haan A. , Vander Poorten H. , Legrelle A. 
Published: September 2010

AbstractThe formation of aluminium diffusion coatings on nickel is considered in molten chloride bath.The coatings obtained by immersion of nickel samples in molten chloride baths containing a pyrosol or a sub‐compound of aluminium are not adherent.By electrolysis of NaCl‐KCl eutectic (+ 10% weight AlCl3) at 750°C and under a current density of 50 mA/cm2, homogeneous layers of Al3Ni2 are coated on nickel.A process of depolarisation appears in the mecanism of electrodeposition of aluminium on nickel.The layers of about 150 μ are adherent, well crystallised and present a very high hardness of about 800 kg/cm2.The resistance to the corrosion in atmospheric air at high temperature is enhanced.
Sodium‐Ammonia Reductions in N‐Heteroaromatic Chemistry. Protodehalogenation and Protodealkylation of Sulphur Containing Pyrimidines, Pyridazines and S‐Triazines
Authors: de Lannoy J. , Gysen A. , Nasielski‐Hinkens R. 
Published: September 2010

AbstractThe Birch reduction of chloro‐pyrimidine, ‐pyridazine and ‐s‐triazine derivatives bearing a prototropic substituent gives the corresponding dehalogenated compounds in good yields. Methylthio‐ and ethylthio‐substituents undergo a reductive cleavage: 4‐amino‐6‐methylthiopyrimidine (II) and 2,4‐bis‐diethylamino‐6‐ethylthio‐s‐triazine (III) are converted to the corresponding mercapto compounds. Moreover, the sodium‐ammonia reagent is able to remove a chlorine atom from a molecule containing a mercapto or alkylthio substituent; the efficiency of this reaction is shown by the one step reduction of 4‐amino‐6‐chloro‐2‐methylthiopyrimidine (VI) and 3‐chloro‐6‐mercaptopyridazine (VII) to the corresponding dehalogenated mercaptans in 66 and 58% yield, respectively.
Note on “the Stereochemical Requirements for Long Range Coupling in α‐Halogenocyclohexanones”
Authors: Anteunis M. , Schamp N. 
Published: September 2010

AbstractIn reply to the paper of Jefford and Waegell [1] it is shown that non‐classical long‐range coupling does exist in 3,3,5,5‐tetrasubstituted‐2‐halo‐cyclohexanones. Following the reasoning of those authors, an even larger abnormal coupling than originally proposed by us [2] would exist. It is illustrated however that in our original assignation of peaks to axial resp. equatorial H‐4 and H‐6 hydrogens, we have not used false premises. Therefore our original statements [2] are maintained.
Essais de Chloration Dirigée: XV. Corrélation Structure‐Réactivité Dans la Photochloration des Alkylbenzènes [1,2]
Authors: Corbiau J. L. , Soumillion J. Ph. , Bruylants A. 
Published: September 2010

AbstractA quantitative discussion of the experimental results previously obtained in the photochlorination of the alkylbenzenes (C6H5‐R: R = C2H5‐,n.C3H7‐,i.C3H7‐,n.C4H9‐,n.C5H11) is presented.The correlation used is as following: logr.r.(a/b) = ρ*(Σσa*– Σσb*) + Ψa– Ψband accounts for the inductive (σ*) and mesomeric effects (Ψ) of the substituents upon the relative reactivity [r.r. (a/b)] of the ≥ C‐H bond; the last one is only acting upon the α position. The absolute value of both parameters (ρ and Ψ) increases with the concentration of the aromatic substrate. The relative magnitude of their actions is commented.
Étude de Complexes Accepteur‐Donneur par Spectrométrie Infrarouge: I. Influence de la Nature du Donneur Carbonylé
Authors: Lecl Nedden G. Ère‐Zur , Duyckaerts G. 
Published: September 2010

AbstractInfrared intensity measurements of the free C = O band have been used to investigate the complex formation between ketones or other carbonylated donorsand antimony trichloride in CCl4solutions using Job's continuous variation method. The dissociation constants of the acceptor‐donor complexes with a 1:1 and 1:2 stoichiometry have been calculated. The sequence of donor basicity based on the 1:1 equilibrium constant is discussed in terms of electronic effects of the substituents R and R.
The Complexes of Ni(II) and Pd(II) with Monothio‐Oxamide and Some of its Derivatives
Authors: van de Cappelle G. L. , Herman M. A. 
Published: September 2010

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

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

AbstractStarting from the Gibbs‐Duhem equations the heats of formation from the collapse and, the equilibrium spreading pressure in monolayers are obtained. Also surface azeotropes are considered. The heat of phase transition of the first order is examined. It results that the Gibbs‐Duhem equation for the monolayer can be written by fixing the dividing surface or relative invariant quantities can be used.