bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution a l'étude de l'action des Bases Sur les Sels d'Ammonium Quaternaires. VI. Réactions de Transposition, D'élimination et de Dimérisation Obtenues A Partir de Sels Quaternaires Dérivés de la 1,2,3,4‐Tétrahydroisoquinoléine
Authors: Wilputte‐Steinert L. , Fery L. P. A. , Nasielski J.
Published: September 2010

Reaction of 2‐methyl‐2‐benzyl‐1,2,3,4‐tetrahydroisoquinolinium iodide with sodium amide in liquid ammonia yields 76% 1‐orthotolyl‐2‐methyl‐1,2,3,4‐tetrahydroisoquinoline resulting from a Sommelet‐Hauser rearrangement. In the same conditions, 2,2‐dimethyl‐1,2,3,4‐tetrahydroisoquinolinium iodide yields 4% N,N‐dimethyl‐2‐vinylbenzylamine resulting from an elimination reaction and 70% 1‐(2‐dimethylaminomethy Iphenyl)‐2‐[2‐(β‐dimethylaminoethylphenyl)]‐cyclo‐propane, probably trans, (IX) resulting from dimerization followed by γ‐elimination.
Ag(I) Complexes of Some ω′‐Aminoalkylpyridinium Compounds
Authors: van Poucke L. C. , De Brabander H. F. , Eeckhaut Z.
Published: September 2010

The stability constants of the Ag(I) complexes of some ω'‐aminoalkylpyridinium compounds are determined by a pH‐metrical method, at 25 deg;C and in 0.5 M KNO3. The results are compared with those obtained in a similar investigation of the Ag(I) complexes of ω‐aminocarboxylic acids. In both cases complexes of the same type are formed and only quantitative differences can be observed.
Shock Tube Study of the Induction Lag in Nitrous Oxide‐Hydrogen System
Authors: Soloukhin R. I. , Tiggelen P. J. Van
Published: September 2010

Induction lags behind incident shock waves have been measured in nitrous oxidehydrogen mixtures diluted with 90 or 95% of argon. The physical magnitudes detected in order to characterize the induction lags are either the OH‐emission at 3075 Å or the interferometric density measurements.

No significant difference appears between both measurements. According to the observations in a low temperature range, the overall activation energy corresponds to 22 Kcal/mole, while at higher temperatures the apparent activation energy is about 60 Kcal/mole.

The results are discussed in terms of a branched mechanism, the chain branching reactions being rate determining below 2500 °K, while the initiation process takes over above this temperature.

The low temperature mechanism confirms the interpretation given to flames burning in the same mixtures.
A New Synthesis of Oxytocin Using S‐Carbobenzoxy‐Cysteines and N‐p‐Methoxybenzyloxycarbonyl‐Amino Acids as Intermediates
Authors: Vandesande F.
Published: September 2010

A new synthesis of oxytocin is described. For the protection of the α‐amino functions the p‐methoxybenzyloxycarbonyl‐group was used. The phenolic hydroxyl of tyrosine was protected by the usual benzyl group. The free thiol functions of the cysteine moieties were protected by the carbobenzoxy group. For building up the peptide chain the step wise p‐nitrophenylester method was used. At the end of the synthesis, a fully protected nonapeptide amide was obtained, namely S–Z–N–pMZ–L–Cys–L–Tyr–L–lle–L–Glu(NH2)–L–Asp(NH2)–S–Z–L–Cys–L–Pro–L–Leu–Gly(NH2).

All the protecting groups from this protected nonapeptide‐amide were removed by a reduction with sodium in liquid ammonia. After oxydation by aeration, oxytocin was obtained in a good yield.
Essais de Chloration Dirigée. XII. Photochloration d'Acétates d'Alkyles Par Agents Chlorants [1]
Authors: Ph. Soumillion J. , Bruylants A.
Published: September 2010

Photochemical chlorination of several alkylacetates. CH3–CO–O–R (with R = n.C3H7, n.C4H9, i.C4H9, n.C5H11), was performed, using trichloromethane‐sulfenyl chloride (TCSE) as chlorinating agent, both with and without benzene as solvent.

As in our previous works, chlorination was limited in order to get a mixture of monochlorinated isomers. Experimental results, expressed in terms of relative reactivity, r.r. (alb), of two hydrogen atoms, were correlated by the equation: magnified image.

The reaction constants ρ*(−1,28) and h (0,112), compared with analogous values obtained in direct chlorination (ρ* = − 084, h = 0,034) show an important increase selectivity.

Reactions were also performed at different temperatures and results are discussed. Some experiments were also made with amyl acetate and trichloromethane‐sulfonyl chloride (TCSO) as chlorinating agent.
NMR‐Experiments on Acetals. XVII. Conformational Equilibria In Trans‐4‐Alkyl‐6‐Methyl‐1,3‐Dithianes
Authors: Gelan J. , Anteunis M.
Published: September 2010

The conformational equilibrium I ⇌ II in the trans‐4‐alkyl‐6‐methyl‐1,3‐dithianes has been computed from the study of the H‐2 proton shifts at different temperatures in pyridine‐chloroform‐carbondisulfide mixed solvent. Thermodynamic data are found in the table. A method to predict shift parameters, above the coalescence temperature, of the individual conformers has been developed and used in the calculations of equilibrium constants.

Furthermore the results show that in general the nature of the alkyl group has only a small influence on the thermodynamic parameters ΔΔH° and ΔΔS°. For R = i.Pr we accept a significant amount of flexible conformation.

Otherwise higher alkyl groups in 4 position prefer the axial position in comparison with methyl.
Nouvelles Voies D'Accès Aux Acides Cinnamiques. Application à la Synthèse des Acides O‐Méthylthio et O‐Méthylsélénocinnamiques Simples et Substitués
Authors: Ruwet A. , Renson M.
Published: September 2010

1‐thio‐ and 1‐seleno‐coumarins are synthesized by cyclization of o‐methylthio and o‐methylselenocinnamic acids. The Reformatsky reaction provides a route to cinnamic acids from o‐methylthio and o‐methylselenobenzaldehydes, acetophenones and benzophenones but ethyl bromacetate behaves abnormally owing to SCH3 or SeCH3; a solution is found by preparing first the organozincic. The Perkin synthesis is also used for benzaldehydes. New methods were investigated from acetophenones and benzophenones: condensation of ethyl cyanacetate and malononitrile with benzylamine as catalyst and condensation with acetonitrile or ethyl acetate and LiNH2. Application is given for several o‐methylthio and o‐methylselenocinnamic acids.
Spiro‐isohumulones: Isohumulones with a 3‐Keto Tetrahydrofurane Moiety
Authors: Maes L. , Anteunis M. , Verzele M.
Published: September 2010

Since 1951 it is known that methanolic alkaline isomerization of humulone produces a mixture of crystalline isomers. This paper shows that the mixture contains the four diastereoisomers with structures 12, 13, 14 and 15 of chart III. It is proposed to name these substances trans‐spiro‐isohumulone I and II and cis‐spiro‐isohumulone I and II respectively.
Une Méthode pour Déterminer la Participation des Chai̊nes Aliphatiques à la Réactivité d'un Centre Fonctionnel
Authors: Vidal B.
Published: September 2010

Nous exposons une méthode qui permet d'étudier, à partir de données cinétiques, l'influence des chaînes aliphatiques sur la réactivité d'un centre fonctionnel qui leur est adjacent.
Electrochemical Growth of NpO2 Single Crystals
Authors: Martinot L. , Machiels A. , Fuger J. , Duyckaerts G.
Published: September 2010

We have prepared NpO2 single crystals by electrochemical reduction of neptunyl chloride in LiCl—KCl between 700 and 870°C, both on pyrolytic graphite and platinum cathodes. The lattice parameter is a = (5.433±0.001) Å.
Synthèses dans la Série du Benzo(b)Sélénophène
Authors: Christiaens L. , Dufour R. , Renson M.
Published: September 2010

Nous étudions la réactivité des méthyl‐2 et méthyl‐3 benzo(b)sélénophènes vis‐à‐vis d'agents électrophiles (réactions de bromuration, de Friedel et Crafts). Nous décrivons également une série de synthèses réalisées sur les positions 2 et 3 de l'hétérocycle de base.
Essais de Chloration Dirigée: XIII. La Photochloration Directe des Hydrocarbures Arylaliphatiques [1]
Authors: Corbiau J. L. , Bruylants A.
Published: September 2010

Photochlorination in liquid phase was performed at various temperatures (from 22 to 98°C) in order to determine the ratio of the various monochlorinated isomers generated during the reaction. The different compounds studied are of general formula C6H5R, where R is equal to: 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: for instance, ethylbenzene gave 90% of the α and 10% of the β‐chloroethylbenzene. Differences between activation energy of the two chlorinations of the same hydrocarbon are relatively high. In the case of C2H5C6H5 the value (Eα ‐ Eβ) amounts 3.130 cal. m−1.
Nouvelle Synthèse de Benzo(b)Furannes, Thiophènes et Sélénophènes Alcoyles ou Aryles en Position 2
Authors: Christiaens L. , Renson M.
Published: September 2010

Nous décrivons une nouvelle synthèse de benzo(b)furannes, thiophènes et sélénophènes substitués en position 2 par un groupement alcoyle ou aryle. Cette voie d'accès originale à de tels hétérocycles est basée sur la cyclisation d'éthers (O, S, Se) portant en position ortho un groupement acétonyle ou phénacyle. Nous examinons également les possibilités de généralisation d'une telle réaction.
Mechanism of Bromine Oxidations: II. Kinetics of Oxidation of Isobutyraldehyde by Bromine in Aqueous Solution
Authors: Kudesia V. P.
Published: September 2010

The Kinetics of Oxidation of Isobutyraldehyde by bromine in Aqueous solution has been studied. The reaction is found to be of the first order with respect to isobutyraldehyde and first order with respect to moleculer bromine. The various activation parameters have been calculated. A hydride abstraction mechanism based on the results of deuterium isotope effect has been suggested.
NMR‐experiments on Acetals: XXII [1]. Conformational Equilibria in Trans‐4,6‐Disubstituted‐1,3‐Thioxanes
Authors: Gelan J. , Anteunis M.
Published: September 2010

With the use of a previously developed method [1] based on (temperature dependent) shift parameters of AB spin systems, the thermodynamic quantities controlling conformational equilibria in trans‐4‐Me‐6‐alkyl‐1,3‐thioxanes have been computed (table 1). The conformations with axial substitution next to the sulphur atom are always in excess. The total energy differences are the result of each time a constant enthalpy, but a variable entropy contribution, the latter in disadvantage of the conformation with the (hindered) axial substituent at the oxygen side. These results are discussed in the light of the previously reported special ring shape of thioxanes [6].
Effet de Solvant sur L'équilibre Prototropique de la 3,4‐Diméthyl‐Isoxazoline‐5‐one
Authors: Maquestiau A. , van Haverbeke Y. , Muller R. N.
Published: September 2010

In the present work, the solvent effect on the equilibrium between the three potential CH, NH and OH forms of the 3,4‐diméthyl‐isoxazolin‐5‐one has been studied quantitatively by N. M. R, I. R. and U. V. spectroscopy. The aromatic OH form being absent, an equilibrium takes place between an associated NH form and free NH and CH forms. The CH structure is the most stable but hydroxylic and basic aprotic solvents favour the NH form.

The dielectric constant of the solvent seems to have but a negligible effect.
Étude par Diffraction de Rayons X de Complexes D'Halogénures Alcalins et de Molécules Organiques: VIII. Structure de Lil.2(NH2)2CO
Authors: Verbist J. , Meulemans R. , Piret P. , van Meerssche M.
Published: September 2010

The structure of Lil.2(NH2)2CO has been determined by three‐dimensional X‐ray analysis. Space group C2/c; a = 11.40, b = 14.38, c = 5.23 Å, β = 101.5° Z = 4.Li+ is surrounded by four O each urea being linked to two Li+. The chains (Li+.2 urea)n so formed are held together by means of N‐H…I− bonds.
NMR Experiments on Acetalsl XXVI. Influence of β‐Substitution on Geminal Coupling Values in 1,3‐Dioxanes
Authors: Swaelens G. , Anteunis M. , Tavernier D.
Published: September 2010

The influences of β‐substituents–either in equatorial or in axial positions–on the numerical value of 2J(H‐2) (the geminal coupling J(OCH2O)) in 1,3‐dioxanes, have been scrutinized. Influences on 2J(H‐2) by the nature and electronegativity of the substituents seem to depend on the orientation of these substituents. Equatorial substituents cause composite influences, alkyl groups leading to an almost independent constant value for 2J(H‐2) = −6.2 cps.

Suitable equatorial ρ‐substituted phenyl derivatives show a numerical decrease with increasing electrodonating capacity (range 6.2‐6.5 cps) however. The same, but more pronounced trend is found for the axial substituents.
Spectroscopie Ultraviolette D'Une Série D'Aldéhydes Dérivés D'Hydrocarbures Polycycliques Aromatiques: I. Étude Théorique de la Fréquence de la Transition 1La et de la Position Des Bandes De Transfert de Charge Avec le Tétracyanoéthylène
Authors: Figeys H. P. , Wilmet‐Devos B.
Published: September 2010

The frequencies of the 1La transitions of polycyclic aromatic aldehydes are related linearly to the energy gap between the highest bonding and the lowest anti‐bonding orbitals in these molecules calculated by an iterative Hückel‐L. C. A. O.‐method. Solutions of the same derivatives and tetracyanoethylene in chloroform show a new absorption band which may be attributed to a charge‐transfer complex. A linear relation is found between the energies of these bands and the highest occupied molecular orbital of the aldehydes.
Nouvelle Voie D'Obtention Rentable du Nitro‐5 Benzo(b)Sélénophène Comparée a D'Autres Méthodes
Authors: Marechal G. , Ruwet A. , Renson M. , Buu‐Hoi N. P.
Published: September 2010

The previously known synthesis of 5‐nitro benzo(b) selenophene is only convenient for the preparation of small quantities. In order to obtain this compound in great quantity for heterocyclic chemistry, new ways have been investigated. They are limited by the present difficulty to reach 2‐methylseleno‐5‐nitro‐benzaldehyde. However the Knoevenagel's reaction applied to 2‐bromoseleno‐5‐nitro‐benzaldehyde itself prepared in two steps from 2‐chloro‐5‐nitrobenzaldehyde is shown to be a new efficient procedure for the synthesis of 5‐nitro‐benzo(b)selenophene. The latter provides 5‐animo‐benzo(b)selenophene and other derivatives.
Organometallic Compounds. XXIV. () Determination of all the possible isomerization reactions of coordination complexes by the use of permutations
Authors: Gielen M. , Vanlautem N.
Published: September 2010

Permutations may be used to describe the transformations of a given complex MLn into one of the n!/hr, possible isomers.

The determination of the n! possible permutations gives all the isomerization paths of this complex occuring by nonbond‐rupture mechanisms.

This is applied to the case of four; five‐ and six‐ coordinate structures and might be applied as well to higher coordination numbers.
Indole Alkaloids: XXIV Unusual behaviour of voachalotine and derivatives in the von braun degradation
Authors: Lampe‐Tirions M. , Kaisin M. , Pecher J.
Published: September 2010

The cyanamides obtained by the von Braun degradation of voachalotine (VIII) and derivatives are all bromine free compounds, formed by a “benzylic” cleavage of the C3N4 bond. The alternatively conceivable allylic cleavage of the C21N4 bond was not observed.

The derivatives I, III and VI (not containing an OH group) yielded cyanamides comprising a Δ 3,14 double bond conjugated to the indole system. This was not observed in the degradation of voachalotine (VIII): the corresponding cyanamide IX contained a cyclic ether, formed by an intramolecular attack of the alcohol group on C3. The cleavage of the C3‐N4 bond can also be assisted by an inter‐molecular process involving alcohols added to the solvent (chloroform). In the latter conditions indeed good yields of the 3‐alkoxycyanamides XII, XIII, XIV and XV were obtained.
Some Constituents of Lycopodium Inundatum L
Authors: Braekman J. C. , Hootele C. , Ayer W. A.
Published: September 2010

Three new alkaloids—inundatine [V], isoinundatine [VI] and dehydrolycopecurine [VII]—have been isolated from Lycopodium inundatum L. together with methyl p‐coumarate [I], α‐onocerine [II], lycopodine [III] and lycodoline [IV].
Group‐Theoretical Analysis of Spin‐Forbidden Transitions
Authors: Peeters J. , Vanquickenborne L.
Published: September 2010

The occurrence of spin‐forbidden transitions in molecular spectra is investigated from a group theoretical point of view. The notion of “useful multiplets” is introduced and its applicability is shown for the case of transition metal complexes. Several detailed tables are given.
Structure Moléculaire et Cristalline du Bromo‐5 Tetraphényl‐1,2,3,4 Cyclopentadiène
Authors: Evrard Guy , Piret Paul , van Meerssche Maurice
Published: September 2010

The structure of bromo‐5 tetraphenyl‐1,2,3,4 cyclopentadiene has been determined by X‐ray analysis. Space group: P212121, Z = 4; a = 8.51, b = 41.99, c = 6.17 Å. The molecule has nearly mirror‐symmetry. The angles between the mean planes of the phenyls and that of the central ring are ϕ(1) = 30.5°, ϕ(2) = 66.5°, ϕ (3) = −69.0° and ϕ (4) = −33.9°.
Regiochemistry in Cycloaddition Reactions of Vinyl Azides with Phenylacetylene[1]
Authors: L'Abbé G. , Hassner A.
Published: September 2010

Vinyl azides and β‐haloalkyl azides combine with phenylacetylene to give a mixture of adducts, whose regiostructure can be resolved by NMR.
A Convenient Synthesis of Chloronitrobenzonitrile Isomers and Homologs
Authors: Grivsky E. M.
Published: September 2010

A new, direct method for the synthesis of 10 position isomers of chloronitro‐benzonitrile and some homologs from the corresponding benzoic acids and methane‐sulfonamide in the presence of phosphorus pentachloride has been developed and exploited. This modification has proved to be more generally applicable than the previously available procedure usingp‐toluenesulfonamide, and the products were obtained in amounts approaching the theoretical yields. A cyclic mechanism for a transformation leading to the formation of these aromatic nitriles is postulated.
Heterogeneous Photosensitization. Part II. Kinetics of the Gas‐Phase cis‐trans isomerization of 1,3‐pentadiene sensitized by 1,3‐cyclohexadiene photopolymer[1]
Authors: de Maré G. R. , Fontaine M‐C. , Goldfinger P. , Huybrechts G. , Sapir M.
Published: September 2010

The gas‐phase cis‐trans isomerization of 1,3‐pentadiene, photosensitized by a thin polymeric film, has been studied at λ ≥ 300 mμ and 50°C in the pressure range 5 to 200 torr. The observed photostationary state and the influence of substrate pressure on the rate of isomerization suggest a reaction mechanism similar to that proposed for triplet photosensitized isomerizations in solutions[2].
Effect of the pH on the Collapse Pressure of Fatty Acid Monolayers Evaluation of the Surface Dissociation Constant
Authors: Joos P.
Published: September 2010

The collapse pressures of stearic and cholanic acid monolayers were measured as a function of pH. The surface phase was treated as a mixture containing acid and soap, and our previously outlined theory concerning the collapse of a mixed monolayer was applied to it. From this results, a surface dissociation constant, different from the bulk value, can be obtained. The experimental data are in good agreement with the outlined theory.
Mesure du Potentiel Standard du couple Pu(III)/Pu(O) Dans L'Eutectique LiCl‐KCl Entre 400 et 600°C
Authors: Not L. Marti , Duyckaerts G.
Published: September 2010

We have measured the standard potential of the system Pu(III)/Pu(0).vs. a Ag/AgCl reference electrode in a LiCl‐KCl eutectic.

The values of the standard potential are reported between 400 and 600°C and compared with the previous determinations carried out with U(III) and Np(III). The Nernst equation is also plotted at several temperatures.
Étude RPE des Radicaux Cyclopentyles Piégés dans un Mélange de Cyclopentane et de Néohexane
Authors: Fauquenoit C. , Dodelet J. P. , Claes P.
Published: September 2010

Nous avons étudié par RPE le radical cyclopentyle formé par irradiation à 77°K de mélanges vitreux de cyclopentane et de néohexane. Le spectre du radical cyclopentyle est mieux résolu que celui provenant de l'Irradiation du cyclopentane pur. Deux configurations différentes du radical cyclopentyle ont été invoquées pour interpréter le spectre RPE observé.
The Thermodynamics of Ionization in Ethanol‐Water Mixtures. II. Ortho Substituted Anilinium Ions
Authors: van De Poel W.
Published: September 2010

Thermodynamic parameters of ionization, δHi0 and δG, i0 were measured at 25°C for a number of ortho substituted anilinium ions in water and in highly aqueous ethanol (X = 0.9).

Larger endothermic maxima were found for δHi0 and δSi0 on going from water to ethanol‐water as solvent than for the corresponding 3‐ and 4‐substituted isomers. The results are treated in terms of the structure influencing effect of ions and neutral molecules in aqueous solutions, and in terms of Heplers “internal”; and “external”; contributions to ionization parameters.

A value of β, the proportionality constant between δHext and δSext, was calculated with the aid of the experimental results. This β value is not significantly different from the one found previously for 3‐ and 4‐substituted anilinium ions.
Kinetics of Bromination of p‐Toluidine
Authors: Kudesia V. P.
Published: September 2010

The kinetics of oxidation of p‐toluidine with aqueous bromine has been investigated at 25°C. Evidences have been provided to establish that the molecular bromine is the principal oxidising agent. There is an isotope effect k2(H2O)/k2(D2O) = 1.36 which is found to be secondary exhibiting that the mechanism does not represent slow proton loss in rate determining step.
The Electrical Resistivity of Rhombohedral NiS
Authors: Pauwels L. J. , Maervoet G.
Published: September 2010

Electrical resistivity measurements are carried out from 4,2 K to 800°K on rhombohedral NiS powder compacts, sintered at different temperatures. The effect of sintering is exposed. NiS γ appears to be a metallic conductor with a room temperature resistivity of 9.2 × 10−5 ωcm and a temperature coefficient of 3.6 × 10−3 deg−1. In the high‐temperature range ρ is proportional to T; in the low‐temperature range (30‐45°K) a T3.84‐law is followed. It is possible to derive a value of about 300°K for the characteristic temperature Θ. At 388°C a discontinuity in the resistivity is found, caused by the γ → β phase transformation.
Les Sulfates Basiques Mixtes de Cobalt et de Zinc
Authors: Lecocq R. , Glibert J. , Breckpot R.
Published: September 2010

The stable basic sulfates of Co and Zn, as obtainable by NaOH at 20°C, are respectively tetra‐ and tribasic.

The mixed basic salts in equilibrium with mixed solutions of the sulfates show a considerable potential retention for Zn corresponding with a depletion of this element in the solution.

Up to 25 at. %, Zn can be held in the hydroxyl sites of the tetrabasic Co structure with a partial bonding energy per atom 1000 times greater than in the pure tribasic salt of Zn.

With larger amounts of Zn, the basicity is lowered and with 40 at. % of Zn the tribasic lattice appears. In this, Co is preferentially held in the sulfate sites.
Calorimetric Determination of ΔH and ΔS Involved in the Complex Formation of Some Metals with 2‐Substituted Pyridine Derivatives
Authors: Goeminne A. M. , Eeckhaut Z.
Published: September 2010

The enthalpy changes involved in the complex formation of Cu(II), Ni(II), Co(II), Zn(II), Cd(II) with several 2‐substituted pyridine derivatives have been determined by direct calorimetric measurements at 25°C, in 0,5 M KNO3 solution. From these and the stability constants of the complexes, δS has been calculated. Changes in δH and δS are discussed in terms of hydrational, inductive and steric effects.
Catalyse Homogène et Hétérogène Comparaison des Deux Processus Lors de L'Hydrogénation de L'éthylène en Présence D'Une Même Espèce Catalytique
Authors: Gosselain P. A. , Hardy J. C. , Simoens G. , Slegers J. , Verbelen R.
Published: September 2010

On a étudié l'hydrogénation de l'éthylène catalysée par un dérivé organométallique du nickel résultant de l'action en phase gazeuse du triéthyl aluminium sur de l'hexanoate de nickel. Ce complexe soluble dans l'hexane est catalytiquement actif en système (gaz/solide) hétérogène et en phase liquide homogène.

Un parallélisme est établi entre ces deux modes de réactions : dans les deux cas, l'équation de vitesse est d'ordre 1 en hydrogène et zéro en éthylène et l'énergie d'activation est voisine de 5 kcal mole−1.
Determination by the mass spectrometric knudsen cell method of the dissociation energies of the group IB chalcogenides
Authors: Smoes S. , Mandy F. , Auwera‐Mahieu A. Vander , Drowart J.
Published: September 2010

The dissociation or atomization energies of the following gaseous group IB chalcogenides were determined to be (in kcal/mole

1 kcal = 4.184 kJ.

):

magnified image

The atomization energies of the remaining subchalcogenides were estimated withDo°,at(M2X)/Do° (MX) = 2.11 ± 0.03, derived from the above results.

In addition, the dissociation energies of the molecules CoAu and NiAu were confirmed.
Reactive intermediates and molecular beam mass spectra of the boranes [1]
Authors: Stafford Fred E.
Published: September 2010

Molecular beam mass spectrometric work on the lower boron hydrides is reported. Borane, BH3, and tetraborane (8), B4H8, were formed by reactions involving loss of BH3, CO, and, in the latter case, H2 from the appropriate molecules. This ensemble of reactions permitted unambiguous identification of each species. A route to B3H7 from B3H7PX3 is proposed. Investigation of the “stable” and “unstable” boranes and isotopically labelled molecules permits correlations of the mass spectra, determination of a structure ((B4H9)2), and identification of fragmentation pathways. Steady state pyrolysis in the ion source is particularly insidious. Because of it, previous appearance potential and theoretical fragmentation studies of e. g., B4H10 are virtually meaningless.
Free Radicals by Mass Spectrometry XLIV. Ionization Potentials and Bond Dissociation Energies for Chloro‐ and Fluoro‐Methyl Radicals
Authors: Lossing F. P.
Published: September 2010

Using monoenergetic electron impact, ionization thresholds have been re‐measured for chloro‐ and fluoro‐methyl radicals produced in a silica furnace. The following ionization potentials have been obtained (in volts): CH2Cl 8.80, CHCl2 8.45, CCl3 8.28, CH2F 8.90. For CHF2 and CF3, only upper limits were measured. Appearance potentials for halomethyl ions from derivatives have also been measured. From a consideration of these and literature values, best values are proposed for the heats of formation of the radicals and their cations.
Photosensitization by Benzaldehyde in the Gas Phase Part II. Cis‐ and trans‐1, 3‐pentadiene
Authors: Maré G. R. De , Fontaine M‐C. , Huybrechts G.
Published: September 2010

The gas‐phase cis‐trans isomerization of 1, 3‐pentadiene photosensitized by benzaldehyde has been studied at λ = 365.5 nm and 60° in the pressure range 50 to 400 torr. From the observed quantum yields and the photostationary state it can be concluded that benzaldehyde transfers its triplet energy at the same rate to both cis‐ and trans‐1, 3‐pentadiene with high efficiency.
Centrifugal Radial Thin‐Layer Chromatography
Authors: Lepoivre A.
Published: September 2010

The general applicability of centrifugal radial TLC is examined. Large plates (40 × 40 cm) are used for analytical and preparative separations. In addition to the very short time of development, some separations are improved compared to the normal radial developments. The possibilities of direct coupling of gaschromatography with radial TLC are also mentioned.
Association de L'Ion Thiocyanate AVEC Différents Cations Étudiée Par Spectrométrie Infrarouge
Authors: Ménard Mll. C. , Wojtkowiak B. , Chabanel M.
Published: September 2010

L'étude infrarouge de solutions de thiocyanates dans des solvants organiques aprotiques a permis d'identifier les paires d'ions de contact LiNCS, NaNCS et MgNCS+. Les déplacements observés sur la bande d'absorption v(C=N) des différentes espèces chimiques sont dus à des effets de constante diélectrique plutǒt qu'à des interactions spécifiques.
Contribution A L'étude des Arséniures de fer, Cobalt et Nickel II. Les Systèmes Ternaires Fe‐Co‐As et Co‐Ni‐As
Authors: Naud J. , Breckpot R.
Published: September 2010

In part I (this Bulletin 80 (1971) 91‐105) the binary systems As‐Fe, As‐Co and As‐Ni were considered. The ternary systems As‐Fe‐Co and As‐Co‐Ni, as obtainable by thermal synthesis at 700° or by precipitation with AsH3, are now studied. The composition range covered is MeAs2‐Me5As2 by thermal synthesis. In this range the Fe‐Co‐As system shows only one cubic variety; this has a Me/As ratio of 1/1,66. By precipitation only nickel can form metal rich derivatives with a ratio Ni/As depending of the pH. In mixed Co+ + +Ni+ + solutions there appears a small selectivity for Ni in the precipitate.

This can be markedly increased by submitting arsenides, thermal or precipitated or natural, to electrochemical reduction in contact with mixed Co+ + + Ni+ + solution. Arsenides with NiAs structure gives rise to Ni11As8 and Ni5As2. MnP and monoclinic type arsenides will only react if they contain a small amount of Ni.

This favours the superficial déposition of amorphous nickel metal, probably anchored on Ni5As2 nuclei formed in a first step.
Sélénazolidines I. Synthèse de la Sélénazolidine, de N‐Alcoylsélénazolidines et de Leurs Dérivés de Substitution en 2
Authors: Draguet C. , Renson M.
Published: September 2010

Nous décrivons un méthode générale de synthèse de la sélénazolidine, ainsi que des sélénazolidines substituées dans les positions 2 et 3.
Transition Metal Complexes Containing Ligands of Pharmacological Interest
Authors: Craciunescu D. , Ben‐Bassat A. H. I.
Published: September 2010

Nicotinamide complexes of the following general composition were prepared: [ML2] [Hgl4], [ML2] [Hg(SCN)4] and ML2(SCN)2, (L = ligand; M  Cu2+, Ni2+, Co2+, Fe2+ and Zn2+). As shown by spectroscopic (IR) results, coordination is achieved by the pyridine nitrogen (C  N), and not by the amidic one (magnified image). The location of the vc‐s and VCN bands supports the existence of a thiocyanatoisothiocyanato isomerism.
Free energy‐, enthalpy‐ and entropy changes of the Ag(I) complexes of ω‐aminosulphonates and ω′‐aminoalkylpyridinium compounds
Authors: Poucke L. C. Van , Thiers G. F. , Eeckhaut Z.
Published: September 2010

The acidity constants of the ω‐aminosulphonates NH2(CH2)SO3− with n = 2, 3,4 and 5 and the stability constants of the Ag(I) complexes of these ligands were determined at 25°, in 0.5 M KNO3. The enthalpy‐ and entropy changes accompanying the formation of the Ag(I) complexes of the same ω‐aminosulphonates and the corresponding ω′‐aminoalkylpyridinium compounds were calculated from calorimetric data. The influence of a negative and of a positive substituent on these thermodynamic functions is briefly discussed.
Radiation Chemistry of 1‐Chloropentane in the Solid Phase II. Influence of Unsaturates
Authors: Ceulemans J. , Claes P.
Published: September 2010

The influence of cyclohexene and 1‐pentene on the yield of the products of the radiolysis of solid 1‐chloropentane has been studied. The observed influence can be explained by an earlier proposed radiolysis mechanism which contains radicalar and ionic reactions.
Configuration et Réactions des Acides 2‐méthyl‐3‐(6‐Méthoxy‐2‐Naphtyl)‐3‐Penténoique et Hexénoïque
Authors: Martin R. H. , Flammang‐Barbieux Monique , Dvolaitzky Maya , Jacques Jean
Published: September 2010

Les acides (esters) mentionnés dans le titre et les dérivés saturés correspondants ont été étudiés par spectrographie de RMN‐1H.
Étude des Métabolites de L'Aspergillus Versicolor (Vuill.) Tiraboschi
Authors: Grandjean J. , Jadot J. , Ramaut J.
Published: September 2010

We have isolated several metabolites by thin layer chromatography. Three structures have been elucidated by nuclear magnetic resonance and mass spectrometry.
Cations Aromatiques Séléniés I. Perchlorates de 1‐Benzothiéno Sélénopyrylium
Authors: Tadino A. , Christiaens L. , Renson M. , Cagniant P.
Published: September 2010

Dans le cadre de l'étude de l'action des réactifs nucléophiles sur les perchlorates de sélénopyrylium, nous décrivons la synthèse des perchlorates de 1‐benzothiéno (3,2‐b) et (2,3‐b) sélénopyrylium. Ces composés relativement stables ont été caractérisés notamment par leurs spectres de RMN et UV. Leur réactivité sera décrite ultérieurement.
A New Synthesis of 1,1‐Dichloromethylketones
Authors: Coppens W. , Schamp N.
Published: September 2010

A new synthesis of 1, 1‐dichloromethylketones is described. Methylketones are converted into cyclohexylketimines, which by N‐chlorosuccinimide are chlorinated specifically to 1,1‐dichloromethylketimines. Hydrolysis yields 1, 1‐dichloromethylketones, containing less than 5% isomers. Overall yields normally are around 50%.
Réduction de L'Acide Sélénique par le Cuivre en Présence D'Ions Cuivriques
Authors: Ladriere J.
Published: September 2010

The reduction of selenic acid by copper is a very slow reaction, strongly depending on temperature and Cu(II) concentration. Selenic acid is reduced into a non‐stoechiometric selenide : Cu2‐X Se (0 <X <0, 2).

The reaction rate is of the first order towards Cu(I) and Se(VI) activities. This is an autocatalytic reaction, one of the products, Cu(II), being able to produce cuprous ions by reaction with metallic copper.
N‐acylamino acids and peptides I. The synthesis of N‐feruloylamino acids
Authors: De Pooter H. , Ali Haider , van Sumere C. F.
Published: September 2010

Procedures for the preparation of N‐feruloylglycine (II), ‐DL‐alanine (XX), ‐DL‐valine (XXII) and ‐L‐leucine (XXIV) by classical methods are proposed and compared. The spectral characteristics and Rf‐values of the substances are included. The compounds were synthesized because N‐feruloylamino acids were required as test substances during an investigation in connection with the expected presence of N‐feruloylproteins in barley [1, 2, 3].
Synthèse de Pyrimidines. Étude de la Condensation de L'éthoxycarbonyl‐Dithioacetate de Méthyle Avec Les Amidines. II
Authors: Snyers M. , Donnez M. , Isbecque D. , Lakhanisky T. , Promel R.
Published: September 2010

4‐Hydroxy‐6‐mercaptopyrimidines substituted in position 2 by amino‐, methyl‐ or phenyl‐groups are obtained in good yields by “the Principal Synthesis”, using a dithioester as the three‐carbon fragment. The reactions are carried out in dioxane. In ethanol containing sodium ethoxide, the 4‐hydroxy‐6‐mercaptopy‐rimidines are produced in low yields along with small amounts of the corresponding 4‐ethoxy‐6‐hydroxypyrimidines. The mass spectra of the pyrimidine derivatives have been recorded. Their major fragmentations are considered.
Synthèse de 4‐Arylsulfonyloxypyrimidines
Authors: Gubin J. , Durant N. , Nasielski‐Hinkens R. , Prorael R.
Published: September 2010

The reaction of p‐toluenesulfonyl chloride with a few alkyl substituted 4‐hydroxypyrimidines (1a through 1d) yields the corresponding 4‐p‐toluenesulfonyloxypyrimidines (2a through 2d). The structure of the products is based on IR and NMR data. In the case of 4‐hydroxy‐6‐methylpyrimidine (1b), a ring‐opened compound was also isolated to which structure 3 was assigned. 3‐Hydroxy‐6‐methylpyridazine (4) undergoes as well O‐sulfonylation.
Les Nitrates Basiques Mixtes et Hydroxydes Mixtes de Nickel et de Cobalt
Authors: Mannoorettonnil M. , Glibert J.
Published: September 2010

The basic nickel and cobalt nitrates, obtained by addition of soda to Ni(NO3)2 or Co(NO3)2 solutions (O, 2 M Me++/1), have respectively the compositions 4 Ni(OH)2.Ni(OH)0, 75(NO3)1, 25 (I) and 4 Co(OH)2.Co1, 25(OH)1.0(NO3)1, 5 (II. They are unstable and tend to transform into hydroxydes by aging or increase of temperature.

In solutions of Ni++ + Co++, at 20°C, precipitation of mixed basic nitrates occurs first and the distribution curve (Ni++/Co prec. as a function of Ni++/Co++ final sol.) shows a change of slope at the transition from basic salt II into I. By prolonging the reaction time, the mixed basic nitrates with predominant presence of cobalt transform into Co1‐xNix (OH)2 while in the nickelrich range, the mixed basic nitrate 5 Ni1‐yCoy(OH)8, 75(BO3)1, 25 (1) is maintened because of the Ni/Co substitution process. A demixing zone separates these two solid solutions.

At 75°C, simply the mixed hydroxydes of nickel and cobalt are formed.
N.M.R. Experiments On Acetals. Part 44. The conformational behaviour of 4‐vinylgroups in 1, 3‐dioxanes. 300 MHz Study of 4‐Vinyl‐5‐Me‐, and 4‐Vinyl‐6‐Me‐substituted 1,3‐Dioxanes
Authors: Anteunis M. , Coryn M.
Published: September 2010

Quantitative conformational data for a 4‐vinyl group in the 1, 3‐dioxane system are obtained trough a study of the conformational behaviour of both trans substituted 4‐vinyl‐6‐methyl‐1, 3‐dioxanes and cis substituted 4‐vinyl‐5‐methyl‐1, 3‐dioxanes. Some appropriate anan co meric model compounds have been prepared. The results were obtained both by a 300 MHz 1H‐NMR spectroscopic study and by epimerisation studies. δG°(4‐vinyl) may be estimated at 2.25 Kcal/mole.
Minimization of a Function to Determine Stability Constants of Complex Species ‐ a Computer Version
Authors: Robbrecht R. , Steyaert H. , Thun H. P.
Published: September 2010

A detailed description is given of a method to minimize a function by computer. This technique was applied to the titration data of bivalent metal‐itaconate complexes, and made it possible to identify the existing complexes, and to calculate their stability constants with their related statistical errors.
Calculation of Detection Limits in Spectrographic Analysis
Authors: Broekaert J. A. C.
Published: September 2010

Methods to calculate detection limits of spectrographic techniques in terms of blank and background are described. Detection limits of “point‐to‐plane” and “plane‐to‐plane” spark excitation for spectrographic determination of Yttrium in solution are compared. The influence of electrode shape and of CsCl‐carrier addition is discussed.
NMR Experiments on Acetals. 40. Long Range Phenomena. 15. Some F, H long‐range phenomena, configurational and conformational aspects from the 300 MHZ NMR spectra of 2‐cf3‐4‐(chloro) methyl‐1, 3‐dioxolanes
Authors: Anteunis M. , van Cauwenberghe R. , Beou Chr.
Published: September 2010

300 MHz spectra are obtained for cis‐, and trans‐2‐trlfluoromethyl‐4‐(chloro) methyl‐1, 3‐dioxolanes. A comparative study with other 2, 4‐disubstituted and 2, 2‐bis trifluoromethyl trisubstituted dioxolanes, allows the assignment of each of the H‐5 atoms. From the extracted spectral parameters typical conformations may be advanced for the CF3‐substituted 1, 3‐dioxolanes.

Some “anomalous”5J (F, H) couplings across oxygen, also observed in 1, 3‐dioxanes, are discussed.
The Leaching of β Cu3, 0As by Oxygen in Concentrated Sulphuric Acid Solutions
Authors: Dewalens J. , Heerman L. , van Simaeys L.
Published: September 2010

The leaching of β Cu3.0 As by oxygen in concentrated sulphuric acid solutions was investigated. Copper is oxidized selectively in solutions containing 1000 g/l H2SO4 at 100 – 140°C with formation of elemental arsenic in the residue.
Highly Specific One‐Step Synthesis of Olefins Deuterium Labelled in Both Allylic Positions, of ENDO, ENDO‐5,6‐Dideuterionorbornene and of 3,5‐Dideuterionortricyclene
Authors: Platbrood G. , Wilputte‐Steinert L.
Published: September 2010

The photoinduced deuteriation of conjugated dienes catalyzed by chromium carbonyl complexes, allows specific labelling in allylic positions.
Spectrométrie de Masse de Pyrazoline‐5‐Ones N1 Substituées. II. 2‐Pyrazoline‐5‐Ones A Structure Fixe et Pyrazoline‐5‐ones Tautomérisables.
Authors: Maquestiau A. , van Haverbeke Y. , Bruyere A.
Published: September 2010

The behaviour under electron impact of fixed 2‐pyrazolin‐5‐ones has been investigated. The main decomposition pathway of these compounds is characteristic of their isomeric structure. The fragmentation pattern of tautomeric N1. substituted pyrazolin‐5‐ones must be interpreted in term of CH form; this suggest that this form prevailes in the gas phase. This result has been verified by I. R. for 1,3‐ and 1,4‐dimethylpyrazolin‐5‐one.
Possible determination of isomerization modes probabilities by A multiple resonance method
Authors: WILLEM R. , Verdin P. , Brocas J.
Published: September 2010

We show that multiple resonance is a possible tool to determine relative probabilities of isomerization modes in the MA4B ligand partition of the trigonal bipyramid. Distinguishability criteria are derived. The scope and limitations of the method are discussed.
Properties of the topological magnetic site exchange matrices
Authors: Brocas J. , Verdin P. , Willem R.
Published: September 2010

The formal properties of magnetic site exchange matrices are derived. The similitude with the algebraic properties of the matrices governing the time evolution of isomer concentration is pointed out. Possible applications are discussed.
Reaction between maleic anhydride and pyrocatechol in the solid‐state
Authors: Singh N. B. , Singh H. N.
Published: September 2010

Kinetics of the reaction between maleic anhydride and pyrocatechol in the solid phase have been studied over a range of temperatures and particle sizes. It is shown that diffusion occurs through surface migration. The nature of interaction has also been investigated using U. V., I. R. and reflectance spectra. It is concluded that charge‐transfer interaction is involved in the formation of the complex. Powder X‐ray diffraction studies show that crystals have tetragonal symmetry.
Brominated phenylalanines
Authors: Anhoury M. L. , Crooy P. , De Neys R. , Eliaers J.
Published: September 2010

(3‐(3‐Bromo‐4‐hydroxy‐S‐methoxy‐phenyl)alanine (Ie) exerts a long‐acting antihypertensive effect in rats and dogs : its synthesis and its optical resolution have already appeared in the literature. 1 Ten new mono‐ and polybrominated phenylalanines with hydroxy‐ and/or methoxy‐groups are here described. These unnatural amino‐acide were synthesized by direct bromination, or via the acetamidomalonic esters (V), or via the azlactones (VI) and the corresponding phenylpyruvic acids (VIII).
NMR experiments on acetals. Part 50 (1). The conformation of cis‐bicyclo[6.4.0]‐10,12‐dioxa‐2‐, and 3‐dodecene
Authors: Anteunis Marc , Coryn M.
Published: September 2010

The preferred conformation of cis‐bicyclo[6.4.0]‐10,12‐dioxa‐2‐dodecene is the one having next to the oxygen of the dioxanic moiety an axial substitution (A, figure 2). This unexpected behaviour stays in contrast to that of the isomeric 3‐dodecene and the corresponding saturated dodecane. These facts are rationalized by the conformational pecularities of the octacyclic moieties, imposing their behaviour on the entire ring system, in despite of a strain of at least 2.25 Kcal/mole in the 2‐dodecene derivative.
Étude de la Stéréoisomérie de Quelques Benzylidenebutenolides, Oxazoline‐ et Imidazoline‐5‐Ones
Authors: Maquestiau A. , van Haverbeke Y. , Muller R. N.
Published: September 2010

Stereoisomerism of some 3‐arylidenebutenolides, 4‐arylideneoxazolin‐ and imidazolin‐5‐ones have been studied by P. M. R. spectroscopy.

Structure in which the aryl nucleus is more remote from the cyclic C=O group is favoured.

The validity of spectroscopic criteria in structural assignment of compounds with two anisotropic groups is discussed.
Configuration interaction study of the lower‐lying excited states of molecular ions.
Authors: Leclerc J. C. , Guissard‐Galloy C.
Published: September 2010

A new computer program, named CIMOL, is proposed for “ab initio” LCAO‐MO‐SCF‐CI calculations on polyatomic molecules. As an example of the program, the study of the lower‐lying excited states of the CH4 ion is presented for three different geometries (C3V, C2V and CS point groups).
Polarity of Hydrogen Bonds on Carbonyl Groups
Authors: Pauwels Herman , Huyskens Pierre
Published: September 2010

From the dipole moments of the complexes and of the separate compounds the di‐pole increments Δμ were computed which result from the complexation of a series of phenols of increasing acidity with several compounds with a carbonyl group: a ketone, an ester, a carbonate, an ureine and two amides. The computations were made for several possible values of the angle between the C = 0 axis and the direction of the hydrogen bond going from 100° to 140°. For a given proton acceptor Δμ increases when the pKa of the proton donor decreases. The derivatives ‐d Δμ/d pKa increase with the basicity of the donor. The dipole increment Δμ also increases with the complexation constant Kab and with the frequency shift ΔνOH. Both derivatives d Δμ/d log Kab, and d Δμ/d ΔνOH increase when the basicity of the proton acceptor becomes higher. From the Badger‐Bauer equation relations between Δμ and the complexation enthalpy ΔHab are obtained. The evolution of Δμ with increasing energy of the hydrogen bond in the whole range of ΔHab cannot be represented by a linear equation but the curves must show an upwards curvature. From ΔνOH the displacement of the proton is deduced and the corresponding contribution ΔμH in the dipole increment is computed. For a given energy of the bond ΔμH is clearly less important for the O‐H … O = C bonds than for the O‐H … N bonds but the dipole increment due to electron displacements is higher. This last increment is mainly due to the rearrangement of the electron clouds in the proton acceptor.
Mesure des Potentiels Standards du Couple Am(III)/Am(O) Dans L'Eutectique LiCl‐KCl Entre 400 ET 600°C
Authors: Martinot L. , Spirlet J. C. , Duyckaerts G. , Muller W.
Published: September 2010

We have measured the standard potentials of the system Am(III)/Am(O) in the molten LiCl‐KCl eutectic within the temperature range 400–600°C. The cell used was the following.

Am/Am(III), LiCl‐KCl/Ag(I), LiCl‐KCl/Ag

A comparison has been made with previous results obtained for actinides and lanthanides.
The Prins‐Formaldehyde Condensation on Myrcene and Simple Derivatives
Authors: De Smet A. , Anteunis M.
Published: September 2010

The Prins reaction on myrcene gives very complex mixtures. Neater reactions are met with partially reduced myrcenes and chelotropic adducts of myrcene with SO, and hexafluoroacetone. Some of these may be done on preparative scale. The reactivity is the highest on the trisubstituted olefinic bond. The nature of the reaction products were assessed by1H‐NMR spectroscopy.
Reactivity of N‐2‐(1,1‐Dichloroalkylidene) Cyclohexylamines. II
Authors: De Kimpe N. , Schamp N.
Published: September 2010

Treatment of N‐2‐(1,1‐dichloroalkylidene) cyclohexylamines with excess sodium methylate in methanol under reflux afforded N‐2‐(1,1‐dimethoxyalkylidene)‐cyclohexylamines, which were hydrolysed to the corresponding 1,1‐dimethoxy‐2‐alkanones. N‐1‐(2,2‐dichloro‐1‐phenylpropylidene) cyclohexylamine on the other hand yielded dehydrochlorination and nucleophilic substitution.
Mass Spectrometry Fragmentation of Phtalides
Authors: van Binst G. , Salsmans R. , Steger Y.
Published: September 2010

The mass spectra of phtalide and some 3‐arylphtalides have been studied. Fragmentation mechanisms are proposed, their elucidation being aided by the study of metastable ion fragmentation and high resolution measurements.
Thioorganic Derivatives of α‐Aminoacids
Authors: Poupaert J. , Bruylants A.
Published: September 2010

A reaction scheme is designed in order to prepare thioorganic functional derivatives of α‐aminoacids: imidothioesters, dithioesters, dithioacids and thioamides. The problem of the N‐protecting group in connection with a critical evaluation of the preparation methods is discussed.
Anisotropy of the Oxygen Kα X‐Ray Emission Band From Mg(OH)2, Single Crystals
Authors: Freund F.
Published: September 2010

The 3σ and 1π molecular orbital contributions to the Oxygen Kα emission band of the hydroxyl ion can be separated by making use of the fact that, in the Mg(OH)2 structure, all OH dipoles are oriented parallel to the c‐axis. The O Kα component due with a 1π → 1s transition at 525.5 eV has its maximum intensity parallel to the crystallographic c‐direction [001], while the 3σ→ 1s component is emitted mainly in the zone (hkO), normal to the c‐direction. The 3σ→ 1s component appears to be split due to electron‐proton interaction, exhibiting two maxima at 524.7 and 526.0 eV.