bluuebunny/crossref_metadata_2025 huggingface dataset:
Solubility of Alcohols, Phenols and Anilines in Water
Authors: Huyskens Pierre , Mullens Jules , Gomez Alfredo , Tack Joris
Published: September 2010

An equation is deduced relating the solubility s of organic substances in water to their distribution coefficient P1 at infinite dilution between cyclohexane and water, to their association constant kM in cyclohexane and to their concentration Cαin their own phase. When the phase in equilibrium with water is crystalline, the entropy of melting ΔSmelting also intervenes as well as the difference between the melting point and the room temperature.

For the alcohols it appears that both P1and kM depend on the number n of carbon atoms in the molecule. In this case the equation becomes: log s = A ‐ 0.597 n + log f, where the constant A is respectively 2.40, 2.69 and 3.05 for the primary, secondary and tertiary alcohols, f is a correction factor which depends on Cαand on kM.

For solubilities lower than 1.5 mol 1−1 the mean deviation between the computed values and the literature data is 10 % in a range of solubilities from 0.0002 to 1 mol l−1.

For the phenols and the anilines P1 depends on the molar volume φ and on the pKa, whereas kM is more or less influenced by the last factor. Or the basis of previously established correlations between these quantities, the solubility of various alkyl and halogenated derivatives of phenol and of aniline are computed and compared with the experimental values. The mean deviation is 25 7 for solubilities going from 0.007 to 0.9 mol 1−1.

The most important factor determining the solubility of the phenols appears to be their molar volume. The role of the pKaof the phenols and of the ortho‐substituents is rather small as a consequence of the cancellation of effects of these factors on P1 and on kM. However, in the case of the anilines the effect of the pKa on their solubility remains important.
Synthesis Op Ketonic Indoles by Friedel‐Crafts Reaction
Authors: Rosseels G. , Peihen M. , Matteazzi J. , Wouters G. , Prost M.
Published: September 2010

The authors report Friedel‐Crafts acylation of 2‐substituted indoles; they prepared 3‐(2‐isopropyl)‐indolyl‐3‐and‐4‐pyridyl ketones.
The Effect of Interbond Angles at Tin Upon 119Sn Chemical Shifts in Organotin Alkane‐α, ω‐Dithiolates and Some Related Compounds
Authors: Kennedy John D. , McFarlane W. , Pyne G. S.
Published: September 2010

1H‐(119Sn) double resonance experiments show that tin shielding in cyclic organotin‐alkane‐α, ω‐dithiolates and in 1,1‐diorganostannacycloalkanes is sensitive to ring size. A shift to low field arises when the interbond angles at tin are abnormally small, and there are accompanying changes in the Lewis acid strength of the tin atom.
Synthesis of a Homologous Series of Protected Oligopeptides Derived from L‐Norvaline
Authors: Bonora G. M. , Maglione A. , Pontana A. , Toniolo C.
Published: September 2010

A series of protected L‐norvaline homo‐oligomers from dimer to heptamer was prepared by the dicyclohexylcarbodiimide and acid azide coupling methods. In the course of our synthetic approach t‐butyloxycarbonyl as the N‐protecting and methyl ester as the C‐protecting end groups were used. The oligomers prepared in this manner were characterized and found to be chemically and optically pure. In the accompanying paper an analysis of the conformational preferences in solution of these low molecular weight protected homo‐L‐norvalines in comparison with isomeric L‐valines will be reported.
Etude Spectroscopique De Quelques β‐Cyano‐Enamines Et Enamines N‐Substituees
Authors: Deswarte S. , Bellec C. , Souchay † P.
Published: September 2010

Les composés cyano‐β carbonylés sont susceptibles ďexister sous les formes cétonique et énolique, Les amines primaires engendrent avec ces composés un produit pour lequel seule la forme énamine R1(CN)C = C R2(NHR3) est décelée à température ordinaire, quelle que soit la méthode d'analyse (UV, IR, RMN).

Lorsque deux isomères géométriques coexistent, ľeffet nucléaire Overhauser permet l'attribution des configurations; l'action d'un chélate d'ytterbium met en évidence la complexation prépondérante de la fonction nitrile.
Structural Form and Nonrigidity in 6, 7, 8, and 9‐Atom Polyhedral Boranes ‐ Molecular Orbital Calculations
Authors: Muetterties E. L. , Beier B. F.
Published: September 2010

Extended Huckel molecular orbital calculations and the Jahn‐Teller theorem provide a reasonable rationale for the solution‐state structures and the stereochemical nonrigidity of some closo borane anions. In the eight‐atom borane, B8H82−, there is a very small energy gap between the highest occupied and lowest unoccupied molecular orbitals for D2d, D4d, and C2v forms, all of which are observed either for the solid or the solution states. In contrast, these gaps are large in Oh‐B6H62−, D5h‐B7H72−, and D3h‐B9H92− and smaller in plausible alternative polyhedral forms of these last three ions which are much more stereochemically rigid than B8H82− and do not show structural ambivalence in solution. Approximate second‐order Jahn‐Teller considerations applied to these various ions, B6 through B9, identify the B8H82− ion as the least rigid in this set of closo‐polyhedral borane ions. Relatively large energy barriers to rearrangements are expected for D3h‐B5H52− and D3h‐B9H92− on the basis of degeneracies in the presumed most favorable transition states or reaction intermediates, C4v‐B5H52− and C4v‐B9H92−, respectively, in the idealized rearrangement paths for these two borane clusters. Since there is a degeneracy in C5v‐B11H112, the Cs form is a far more reasonable transition state or intermediate for rearrangements of the highly fluxional C2v‐B11H112− ion.
Restricted Rotation in 4‐Formyl Pyrazole
Authors: Elguero J. , Marzin C. , Peek M. E.
Published: September 2010

N‐unsubstituted pyrazoles with identical substituents at position 3 and 5 behave, in NMR spectroscopy, as if they had a C2v symmetry; this symmetry became Cs in the case of pyrazole below 178 K.
Effect of Hydrogen Bonding on Acid‐Base Equilibria and Titrations in Organic Aprotic Solvents
Authors: Kolthoff I. M.
Published: September 2010

For convenience a distinction is made in the literature between amphiprotic and aprotic solvents. It would be fair to consider a solvent amphiprotic when it yields a stable lyate ion. Our work has been confined mainly to two solvents, acetonitrile, AN (ϵ = 36), and dimethylsulfoxide, DMSO (ϵ = 46). In the literature DMSO is usually considered as an aprotic solvent; however, it yields a stable lyate ion, called dimsyl1. The analytical uses of sodium and K dimsyl are discussed later on. We have selected AN and DMSO as solvents, as their dielectric constant E is of the order of 40 and tetraalkyl salts in dilute solutions can be considered to be completely dissociated. AN is a very much weaker base than water, and has been classified as a protophobic aprotic solvent, while DMSO is a stronger base than water and is classified as protophilic. As will be seen, AN is a very poor H bond acceptor, being much weaker than water, while DMSO is a stronger H bond acceptor than water. The effects of H bonding on monoprotic acid‐base equilibria in these two solvents has been reviewed in a recent paper2. To avoid repetition, only the main effects will be summarized.
Critical Evaluation of an Automatic Photoplate Processing System for Spark Source Mass Spectra
Authors: van Hoye E. , Adams F. , Gijbels R.
Published: September 2010

A system for reading and interpreting photographically recorded spark source mass spectra using a computer coupled microdensitometer is discussed. Its essential features are: (1) correction for line width, (2) correction for background, (3) possibility of converting the measured transmissions into optical densities, Seidel values or transmission factors, (4) possibility of choosing two calculation methods (the least‐squares method and the “averaging slope” method), (5) improvement of the precision of the measurements by simultaneous processing of the data relative to all the available isotopes of a single element, and (6) a continuous interaction between operator and computer allowing erroneous data to be eliminated at various stages of the processing.

A description of the commercially available program is given. The precision of the system is evaluated by repeated analyses of the same photoplate, which was obtained by the measurement of a very homogeneous standard reference sample (NBS ‐ low alloy steel). Its internal reproducibility is assessed using the known isotopic ratios of multi‐isotopic elements.
Sodium Borohydride Reduction of 1,2,4‐Trisubstituted‐1, 2‐Dihydropyridines
Authors: Thiessen L. M. , Lepoivre J. A. , Alderweireldt F. C.
Published: September 2010

The sodium borohydride reduction of 1,2,4‐trisubstituted 1,2‐dihydropyridines yields Δ3‐ and Δ4‐tetrahydroderivatives. The predominant derivative in most of the cases is the Δ3‐derivative although starting from the corresponding pyridinium ions only the Δ4‐tetrahydrocompound is obtained. The 1H‐NMR spectra of the trisubstituted dihydro‐ and tetrahydropyridines are given and discussed.
Studies in Organic Mass Spectrometry. XXI: Cyclic bromonium ions from ω‐phenoxy alkylbromides
Authors: van De Sande C. C.
Published: September 2010

ω‐Phenoxy alkylbromides are used as model compounds in the determination of factors governing the abundances of cyclic bromonium ions in the gas phase.
Cyclopentanones XIV. The synthesis of a prostanoid synthon starting from 3‐alkyl‐1,2,4‐cyclopentanetriones
Authors: van Brussel W. , van Hooland J. , De Clercq P. , Vandewalle M.
Published: September 2010

3‐Alkyl‐1,2,4‐cyclopentanetriones can readily be converted to all trans 2,3‐dialkyl‐1,4‐cyclopentanediols. The latter compounds are intermediates for the synthesis of a prostanoid synthon, known as Corey's lactone, when the alkyl substituents contain appropriate functional groups. The conversion of two different sets of side‐chains to readily distinguishable two‐carbon and one‐carbon aldehyde units is described. Extensive 1H‐NMR data are included.
Synthesis, Spectroscopic Properties and Configurational Stability of Organometallic Compounds with a Tin‐Iron Bond
Authors: Gielen Marcel , Hoogzand Cornells , van Den Eynde Ivan
Published: September 2010

Organotin compounds with a tin‐iron bond are configurationally stable within the NMR time scale, even in the presence of nucleophiles.

The spectroscopic properties of (CH3)[C6H5C(CH3)2CH2](C6H5)Sn‐Fe(CO)2(n‐C5H5), I, (CH3)2(C6H5)Sn‐Fe(CO)(n‐C5H5)[(C6H5)3P], II, and of a series of compounds (C6H5)n (CH3)3‐nSn‐Fe(CO)2(n‐C5H5), III (n=0,1,2,3) are described and discussed.
Helicenes. Chemically Induced Asymmetric Photosyntheses of a Helicene Skeleton: 2‐ and 3‐Menthyloxycarbonyl [6] Helicene
Authors: Cochez Y. , Jespers J. , Libert V. , Mislow K. , Martin R. H.
Published: September 2010

Two asymmetric photosyntheses of a [6] helicene skeleton, induced by (‐) menthyl esters, have been studied (Ia–IIa and Ib–IIb). The optical yield of the two reactions is of the same magnitude (5‐6%), but the substituted helicenes produced in excess have opposite configurations.
Vibrational Analysis of Some Simple Esters Part I. CH3HNCOCOOCH3
Authors: Desseyn H. O. , van Der Veken B. J. , Herman M. A.
Published: September 2010

The infrared and Raman spectra of CH3HNCOCOOCH3, and the nitrogen‐deuterated derivative have been recorded; the fundamentals have been assigned and a valence force field has been calculated.
Conformational Effects on the Valence Electronic Structure of Polyethylene
Authors: Delhalle S. , Delhalle J. , Demanet Ch. , Andre J. M.
Published: September 2010

Band structure for the T, TG, G and TGTG' conformations of polyethylene are computed in the framework of the extended Hückel method. Significant changes of the CC bands are observed in the density of states and could in principle be detected by an XPS experiment.
Density and Vapour Pressure of the Propylene Glycol‐Water System from 15 to 50°C
Authors: Verlinde J. R. , Verbeeck R. M. H. , Thun H. P.
Published: September 2010

Densities and vapour pressures of the propylene glycol‐water system were determined from respectively 20 to 45°C and 15 to 50°C at 5°C intervals. The dependence on concentration and temperature of excess and partial volumes revealed volumetric anomalies similar to monohydric alcohol‐water systems. The dependence on concentration and temperature of the vapour pressure apparently obeyed Raoult's law though this would not be expected from the volumetric behaviour.
Fragmentation D'Hétérocycles Sous L'Impact Electronique. Détermination de schémas de fragmentation par la technique C.I.D./M.I.K.E
Authors: Maquestiau A. , van Haverbeke Y. , Flammang R. , Huisgen R. , Chae Y. B.
Published: September 2010

Air introduction in the second field‐free region of a reversed geometry mass spectrometer induces an important number of fragment ions which are recorded by scanning the ESA voltage. These C.I.D./M.I.K.E. spectra [collision induced dissociations/mass‐analysed ion Kinetic energy spectral are very characteristic of the structure of the stable ions obtained in a normal magnet current scanning and can be used to derive very quickly fragmentation schemes. Application of this technique in the field of heterocyclic compounds (dihydrotetrazines) is discussed.
1H NMR Study of 2‐Deoxy‐D‐Arabino‐Hexopyranose (2‐Deoxy Glucopyranose), 2‐Deoxy‐D‐Lyxo‐Hexopyranose (2‐Deoxy Galactopyranose) and 2′‐Deoxy Lactose. Shift Increment Studies in 2‐Deoxy Carbohydrates
Authors: De Bruyn A. , Anteunis M.
Published: September 2010

Complete analyses of the 1H n.m.r. spectra at 300 MHz of D20 solutions of 2‐deoxy‐D‐arabino‐hexopyranose, 2‐deoxy‐D‐lyxo‐hexopyranose and 2′‐deoxy lactose. Chemical shifts in the deoxy monosaccharides and in 2′‐deoxy lactose are compared with those previously obtained in the parent aldohexopyranoses, glucobioses and D‐galactopyranosyl‐D‐glucoses. Increment values are suggested in order to predict chemical shifts in 2‐deoxy derivatives from the well known rules for aldohexopyranoses.
Chemical studies of marine invertebrates. XVIII. Four novel polyhydroxylated steroids from Sinularia dissecta (Coelenterata, Octocorallia, Alcyonacea)
Authors: Bortolotto M. , Braekman J. C. , Daloze D. , Tursch B.
Published: September 2010

Four novel polyhydroxylated steroids have been isolated from Sinularia dissecta: 24ζ‐methylcholestane‐3β,5α,6B‐triol (I), 24ζ‐methylcholestane‐3β,5α,6β‐triol 6‐monoacetate (II) and the corresponding 24‐methylene derivatives III and IV.
Vibrational analysis of some esters, characteristic pattern for the ester function. Part II: (CH3)2N Co COOCH3 and KOOC COOCH3
Authors: Desseyn H. O. , van Der Veken B. J. , Herman M. A.
Published: September 2010

The infrared and Raman spectra of (CH3)2NCOCOOCH3 and KOOC COOCH3 have been recorded, the fundamentals have been assigned, and a valence force field has been calculated.
Étude par spectromètrie raman de l'association ionique du bisulfate de tetrabutylammonium
Authors: Lambeau Y. , Maes G. , Zeegers‐Huyskens Th.
Published: September 2010

Raman spectra of Bu4NHSO4 dissolved in acetonitrile have been obtained at 25°C for concentrations ranging from 1 to 12×10−2 mol. dm−3. From intensity measurements of the νS‐O (A1) stretching vibrations at 1050 cm−1 (free HSO4−) and 1010 cm−1 (bonded HSO4−), the ionic dissociation coefficient is evaluated. The association constant is 42.6 mol.dm−3. At the studied concentrations no multiple ion aggregates can be detected in the solution.
Isolement et structure de la deoxyaverufinone et de la dehydroaverufine: Deux metabolites de l'aspergillus versicolor (vuillemin) tiraboschi
Authors: Berger Yves , Jadot Joseph , Ramaut Jean
Published: September 2010

We have isolated two new metabolites from a culture of Aspergillus versicolor by thin layer chromatography. The structures of these metabolites, named deoxyaverufinon and dehydroaverufin, have been elucidated by nuclear magnetic resonance and mass spectrometry.
On the sign of the anisochrony of diastereotopic groups
Authors: Devriese G. , Ottinger R. , Zimmermann D. , Reisse J. , Mislow And K.
Published: September 2010

The NMR anisochrony which characterizes the diastereotopism of the CH3 groups in an isopropyl group attached to a chiral residue is defined not only in magnitude but also in sign. The absolute signs of the anisochronies were determined for two series of derivatives of the type XYZC‐CH(CH3)2. Sign inversions were observed for a number of compounds belonging to the same homologous series when compared by 1H or 13C NMR spectroscopy.
The infrared spectrum of 2‐chloro‐1‐(4‐fluorophenyl)‐1‐ethanone
Authors: Seth‐Paul W. A.
Published: September 2010

The i.r. spectrum of 2‐chloro‐1‐(4‐fluorophenyl)‐1‐ethanone has been recorded in the solid state (KBr and nujol) and in solution (CCl4 and CS2). The fundamentals have been assigned in terms of C1 symmetry.
Kinetics of intermediate states in the electrocatalytic reduction of acetone
Authors: Florequin P. , Feyaerts K. , Juliam B. , De Hemptinne X.
Published: September 2010

Electrocatalytic reduction of acetone to propane on a platinum catalyst in acid electrolyte is studied. By applying square wave modulation to the electrode potential, it is possible to determine the kinetics of the formation of adsorbed intermediates. Voltage and H+ ‐ion concentration effects on the observed relaxation times give arguments for a discussion of the detailed mechanism of the process.
Analysing iron ores with Mossbauer spectroscopy
Authors: Govaert A. , Dauwe C. , Plinke P. , De Sitter J. , De Grave E. , Robbrecht G.
Published: September 2010

In previous papers (1, 2) the authors have pointed out the influence of the grain size on the shape of the Mössbauer spectra of goethite (α‐FeOOH). In this paper the correlation between the particle size and the relative Mössbauer constant of goethite is investigated. It is found that only those goethite samples which have in their Mössbauer spectra a “superparamagnetic” fraction at room temperature show a variation of the relative Mössbauer constant with respect to well crystallized materials so that for such samples correction has to be made in Mössbauer quantitative analyses. Further the relative Mössbauer constants for all the iron compounds appearing in iron ores have been determined, taking into account the eventual excess of water. The knowledge of these data enabled us to determine the composition of several iron ores.
Emission spectrographic determination of all rare earths in solutions by hollow cathode excitation
Authors: Broekaert J. A. C.
Published: September 2010

The applicability of a hot hollow cathode discharge lamp for the simultaneous determination of all rare earths (R.E.) in aqueous solutions is investigated. The construction of the lamp,the vacuum system and the power circuit is described. The influence of discharge parameters and the presence of third elements on the obtained detection limits is discussed.
Resin analysis in dissolving pulps
Authors: Cornille G. M. , Schepens Z. , Platteau F.
Published: September 2010

A method based on gas and liquid chromatography was developed for analysis of wood pulp resins. Results obtained with sulphite and sulphate dissolving pulp resins are given and discussed.
Preparation of (substituted) 3,3‐dimethyl‐3‐sila‐1‐heterocyclohexanes
Authors: Dedeyne Raymond , Anteunis Marc J. O.
Published: September 2010

The preparation of four series of 3,3‐diMe‐3‐sila‐1‐X‐cyclohexanes (with X=O, S, NMe, Se, Te) is reported. These series are: the parent compounds, the 2‐phenyl derivatives, the 5‐tert. Bu derivatives and the 6‐Me derivatives.

Attempts to prepare 4‐substituted derivatives along analoguous synthetic routes were unsuccessful.
Préparations de Phenoxyalkylamines Substituées
Authors: Waefelaer Ad. , Pecher J. , Dubois A. , Semet J. , Poultier P.
Published: September 2010

Several new phenoxyalkylamines (8 to 17) were obtained either by reductive ammonolysis of phenoxyalkanones (2), by reduction of phenoxycyanoalkanes (4), by reduction of oximes (3) or by the application of the Gabriel reaction of phenoxyhalogenoethanes (5), depending upon the nature of the aliphatic chain or upon the substituents on the aromatic ring.
Refractive index of the propyleneglycol ‐ water system from 15 to 50 °C
Authors: Verbeeck R. M. H. , Thun H. P. , Verbeek F.
Published: September 2010

Refractive indices of the propyleneglycol‐water system are determined from 15 to 50°C at 5°C intervals using the sodium D‐line. An equation relating the refractive index to weight percent propyleneglycol and temperature is proposed. The change of the refractive index of the system deviates markedly from a linear function of the composition. The molar refraction for the mixtures is found to be nearly additive and temperature independent.
Étude des Produits Secondaires Formés Lors de la Synthèse de 1,4‐Diméthyl‐2‐Alkyl (Aryl) Imidazoline‐5‐Ones
Authors: Maquestiau A. , van Haverbeke Y. , Flammang‐Barbieux M. , Beaufays‐Bar F. , Dereppe J. M. , Touillaux R.
Published: September 2010

During the synthesis of 1,2,4‐trimethylimidazolin‐5‐one, three other compounds were isolated, the structure of which can be ascribed as α‐acetylamino‐N‐methylpropionamide, meso and dl dimers. NMR (1H and 13C), U.V., I.R. and mass spectral data are described. The configurational attributions of the dimers are based on RX measurements, Some results obtained for 2‐ethyl‐and 2‐phenylimidazolinones are also discussed.
L'Utilisation D'Orbitales Localisées Dans L'Étude Theorique des Molécules IV. Le Polyéthylène Dans Sa Conformation T
Authors: Leroy G. , Peeters D. , Rosoux‐Clarisse F.
Published: September 2010

Nous avons calculé la structure de bandes du polyéthylène dans sa conformation T par notre procédé quantique paramétrique basé sur l'emploi d'orbitales localisées. Cette méthode très simple fournit des résultats comparables à ceux des procédés ab initio. Dans sa version semi‐empirique elle conduit à une structure de bandes très voisine de celle obtenue par ESCA. On retiendra particulièrement l'excellent accord entre les largeurs totales de bandes de valence semi‐empirique et expérimentale.
Synthesis of 3‐0‐o.coumaryl‐, 4‐0‐o.coumaryl‐and 3‐0‐ferulyl‐d‐(‐)‐quinic acid. Improved synthesis of 3‐0‐sinapyl‐d‐(‐)‐quinic acid
Authors: De Pooter H. , De Brucker J. , van Sumere C. F.
Published: September 2010

The title compounds were obtained by a reaction sequence starting from diphenylmethyl 4,5‐0‐isopropylidenequinate. Suitably protected cinnamyl chlorides were condensed with this compound, followed by reaction of the intermediate esters with hydrazine hydrate, and then with acetic acid‐formic acid‐water. The total yields of 3‐0‐o.coumaryl‐ and 3‐0‐ferulyl‐D‐(‐)‐quinic acid were respectively 11% and 20%, while the yield of 3‐0‐sinapyl‐D‐(‐)‐ quinic acid was increased to 15%, comparing favourably with the published yield of 7%. From a test reaction, where the intermediate 3‐0‐(O‐methoxycarbonyl‐o.coumaryl)‐ester was first treated with acid and then briefly with alkali, a minor amount of contaminated 4‐0‐o.coumaryl‐D‐(‐)‐quinic acid was obtained as the only reaction product.
The crystal structure of zinc malate trihydrate
Authors: Lenstra A. T. H. , van De Mieroop W.
Published: September 2010

Zinc Malate Trihydrate crystallyses in the monoclinic space‐group P21 with a=5.791 Å; b=8.468Å; c=9.079Å, γ=105,66° and Z=2.

The structure was solved by automated Patterson techniques and refined by block‐diagonal least‐squares to a final R‐value of 0.026.

A network of hydrogen atoms was found. Not all non‐aliphatic hydrogen atoms are involved in hydrogen bonding.
Reactivity of N‐1‐(2,2‐dichloroalkylidene) amides
Authors: Kimpe Norbert De , Verhé Roland , Buyck Laurent De , Dejonghe Walter , Schamp Niceas
Published: September 2010

A general synthetic route to N‐1‐(2,2‐dichloroalkylidene) amides is described, starting from aliphatic 2,2‐dichloroaldehydes and an appropriate N‐unsubstituted amide. The adducts thus formed were converted into N‐(1,2,2‐trichloroalkyl) amides with thionylchloride and subsequently dehydrohalogenated with triethylamine. These N‐acyl α,α‐dichloroaldimines were found to be very apt to nucleophilic addition at the activated carbon‐nitrogen double bond, producing stable adducts. The configuration of the adducts in solution was determined by NMR‐spectroscopy. Treatment of the title compounds with lithium aluminium hydride in diethylether afforded 1,2‐dialkylaziridines. The reactivity of these N‐acyl α,α‐dichloroaldimines was compared with the reactivity of the N‐alkyl analogues and the corresponding oxygen analogues, i.e. α,α‐dihalogenated aldehydes.
Synthèse de dérivés de benzoxazepines. I. 5‐aryl‐2,3‐dihydrobenzo [f] 1,4‐oxazepines
Authors: Waefelaer A. D. , Pecher J. , Dubois A. , Poultier P.
Published: September 2010

Several new 5‐aryl‐2,3‐dihydrobenzo [f] 1,4‐oxazepine derivatives (10) to 25) were obtained in high yields by cyclodehydration of N‐phenoxyalkylbenzamides derivatives (26 to 41).
Systèmes aromatiques à 10 électrons π dérivés de l'aza‐1 pentalene. III. Recherches dans la série du pyrazolo [3,4‐c] pyrazole
Authors: Gonzalez E. , Sarlin R. , Elguero J.
Published: September 2010

The annular tautomerism of 3,4‐dimethyl‐6‐phenyl‐pyrazolo [3,4‐c]pyrazole is discussed on the basis of its 13C NMR spectrum and the spectra of two of its methylated and acetylated derivatives.
Isotope selective chemical activation of ethylene by high power I.R. laser pulses
Authors: Bastiaens J. , De Keuster D. , De Hemptinne X.
Published: September 2010

Chemical processes in C2H4 irradiated with CO2‐laser pulses are investigated. In the higher pressure domain (>5 torr) a focused laser beam initiates a plasma, while C2H4 dehydrogenises to C2H2. If the beam is not focused, there is no dehydrogenation but C2H4 is capable to react with HCl. In the very low pressure domain a new chemical reaction is observed which is interpreted as being a consequence of multiple photon absorption. Isotope selectivity is investigated.
1H‐NMR spectral parameters of some 1,4‐dihydroxy‐2,3‐dialkylcyclopentanes: The configurational dependent magnitude of some 1H‐NMR spectral parameters
Authors: De Clercq P. , Samson M.
Published: September 2010

The configuration of some 1,4‐dihydroxy‐2,3‐dialkylcyclopentanes is assigned on the base of their 1H‐NMR spectral parameters. The interaction of the hydroxyl group with some side chains is discussed. It is shown that the magnitude of the 1H‐NMR spectral parameters of specific hydrogen atoms in some side chains is dependent on the configuration.
Cationic polar cycloaddition with ynamines, formation of a ten‐membered nitrogen ring by twofold ynamine insertion into a 3,4‐dihydroisoquinolinium salt: A dihydrobenzo(d)azecine derivative and its rearrangement to a substituted tetrahydrobenzo(g)quinoline via 1,7‐sigmatropic hydrogen shift
Authors: Fuks R. , Merenyi R. , Viehe H. G.
Published: September 2010

The reaction of 3,4‐dihydroisoquinolinium salt 11 with phenyl‐N,N‐dimethylaminoacetylene 12 affords the (1:2)‐adduct, the dihydrobenzo(d)azecinium salt derivative 13. The structure assignment is based on a preliminary X‐ray analysis as well as on analytical and spectral data. It is assumed that 11 forms with the ynamine a 1,4‐cationic polar system 14 which reacts with a second mole of ynamine 12 (now as polarophile) in a 42 cycloaddition to give compound 16. which rearranges to 13. Heating 13 in vacuo at 230‐265° leads to a dealkylation product having the tetrahydrobenzo(g)quinoline structure 19. Its formation can be explained by a 1,7‐hydrogen shift followed by an electrocyclisation of 17.
Contribution des Calculs Quantiques à L'Elucidation de la Structure en Solution de L'Acide Ribonucléique de Transfert par les Techniques de La RMN
Authors: Pullman B.
Published: September 2010

Les spectres RMN de haute résolution des acides ribonucléiques de transfert (tARN) présentent dans l'eau une série de résonances comprises entre −11 et −15 p.p.m. qui sont attribués aux protons U‐N3H et G‐N1H impliqués dans les liaisons hydrogéne entre les paires de bases. Les positions des résonances sont les résultantes des valeurs “intrinsèques” caractéristiques des paires A‐U et G‐C isolées et de leur perturbation sous l'effet d'empilement due essentiellement aux courants π de bases. Les calculs quantiques de ces effets ont permis l'assignation des résonances observées aux paires de bases spécifiques et ont ainsi contribué d'une façon décisive à l'élucidation de la structure secondaire et tertiaire des tARN en solution.
Problèmes méthodologiques en chimie quantique
Authors: Berthier G.
Published: September 2010

L'analyse des diverses difficultés qui se présentent lors de l'application des méthodes issues de la mécanique ondulatoire (comme la méthode des orbitales moléculaires) à l'étude des structures atomiques et moléculaires fait apparaître les points suivants: les problémes liés à l'évaluation des intégrales atomiques de base et à la détermination de fonctions d'onde monoélectroniques à partir de celles‐ci peuvent être considérées actuellement comme résolus, mais la détermination de fonctions d'onde totales précises reste encore délicate. Sur l'exemple de la barrière de rotation de l'éthane, on montre l'influence de tels calculs en physico‐chimie.
Some calculations on the absorption and emission spectra of benzoic acid
Authors: Catalán J. , Macías A.
Published: September 2010

This paper presents some calculations on the monomer and dimer of benzoic acid using optimized molecular geometries. The calculated levels and transition moments are in good agreement with experimental results and they give a good account of some particular features of the absorption and emission spectra of benzoic acid.
Les fonctions de Hartree‐Fock‐Slater Comme Base Pour des Calculs de Perturbation À un Électron Pour Molécules. II. L'Advantage de la Formulation Dipôle Vitesse‐Dipôle Longeur Pour la Polarisabilité de L'état Fondamental
Authors: Trsic M. , Laidlaw W. G. , Ziegler T.
Published: September 2010

On montre que pour le calcul par perturbation de la polarisabilité dipolaire électrique avec une base de fonctions Hartree‐Fock‐Slater, il est particulièrement avantageux de utiliser la formulation mixte dipǒle vitesse‐dipôle longeur. A l'origine de ce résultat est le fait que la formule mixte est moins sensible aux erreurs par manque de corrélation que les formules dipole longueur ou dipǒle vitesse pures.
Les Sulfates Basiques Mixtes de Cuivre et de Zinc
Authors: Glibert J.
Published: September 2010

The pure basic sulphates of copper and zinc obtained at 20°C by addition of soda to CuSO4and ZnSO4. solutions have the respective compositions Cu4(OH)6SO4(monoclinic symmetry) and 3 Zn(OH)2·ZnSO4·4 H2O (hexagonal symmetry with double layers). In mixed solutions (10 g Me++/l), the solid solution Cu4‐xZnx(OH)6SO4precipitates at the low zinc concentrations. The distribution curve shows a change of slope at 25% Zn at. (x = I). A transition zone caracterized by a continue modification of the structure and the hydration of the precipitate separates this compound from the tribasic sulphate of zinc saturated by copper (33% Cu at.). For this solid solution the substitution occurs in the hydroxide layers only. The distribution factor indicates a continue selectivity for copper in the different phases.
Chemical Studies of Marine Invertebrates. XXII. (1) Two Novel Sesquiterpenes from Soft Corals of the Genera Lemnalia and Paralemnalia (Coelenterata, Octocorallia, Alcyonacea)
Authors: Daloze D. , Braekman J. C. , Georget P. , Tursch B.
Published: September 2010

The structure and absolute configuration of 2‐desoxylemnacarnol (IV) and 2‐desoxy‐12‐oxolemnacarnol (V), two novel sesquiterpenes isolated from soft corals of the genera Lemnalia and Paralemnalia were established by chemical correlation with lemnacarnol [II].
Analyse Conformationnelle des Dérivés Arylacétiques et Propioniques à Activité Antiinflammatoire
Authors: Dive G. , Lapière C. L. , Leroy G.
Published: September 2010

By conformational analysis using the CNDO method we have attempted to outline the common molecular fragments for different arylacetic acids with anti inflammatory activity. The calculated energies for the different conformations give evidence for a conformation common to all these products.
Enethiols IX Alkylation of 2‐Mercapto‐Cinnamic Acids by Ion Pair Extraction Technique
Authors: Jensen L. , Thomsen I. , Lawesson S.‐O.
Published: September 2010

On Alkylation of tetrabutylammonium salts of 2‐mercapto‐cinnamic acids the corresponding S‐alkylated acids are produced. Subsequent alkylation then gives the corresponding esters.
Solution Conformation of the Antibiotic 3823A (Monensin A)‐Sodium Salt
Authors: Anteunis Marc J. O.
Published: September 2010

Extensive double irradiation experiments allowed the almost complete unraveling and extraction of the parameters in the 1H‐nmr spectrum of Na+‐Monensin (1). From this it is concluded that the solution conformation is in its details highly similar to the crystal state of the Ag+ salt. Thus rings A and E are in a somewhat distorted chair, both rings B and D are in an envelope (with the flap at respectively C‐10 and C‐18) while ring C is in a 1514T(wist). An unusual high screening and consequently low rate of proton exchange was observed for some hydroxyl protons, especially in C6D6. The small couplings observed where OH‐protons are involved allow a further deeper insight in their spatial arrangement and in their participation as ligand and hydrogen bonding. Some differences with the solid state are noted here.
The Synthesis of L‐γ‐Glutamyl 2‐Aminohexan 3‐One Isolated From Russula Ochroleuca
Authors: Welter André
Published: September 2010

The assignment of structure I to a new L‐γ‐glutamyl amine produced by Russula Ochroleuca has been confirmed by synthesis.
Pulse Polarographic Determination of Ytterbium in Minerals
Authors: Steeman E. , Temmerman E. , Verbeek F.
Published: September 2010

Differential pulse polarography was used for the quantitative determination of ytterbium(III) in minerals and oxides of other lanthanides. As the reduction occurs at fairly negative potentials and the reduction of hydrogen ions interferes at low pH the number of suitable supporting electrolytes is limited. At pH > 6 hydrolysis effects cause the reduction peak current to decrease as a function of time. Down to 5.10−‐8 M ytterbium(III) can be determined in the supporting electrolyte LiCl (0.1 – 1 M) at pH 5. The analysis of ytterbium(III) in commercial samples showed average relative standard deviations which do not exceed 7%.
Potentiometric Determination of the Thermodynamic Solubility Product of Calcium Fluoride
Authors: Verbeeck Ronald M. H. , Khan Rizwan A. , Thun Harry P.
Published: September 2010

The ion activity product of calcium fluoride is determined with calcium‐and fluoride selective electrodes using the cell F‐ISE/Ca2+, F−,H2O/Ca‐ISE

A reproducibility of 0.01 pI units is obtained.

From these measurements a thermodynamic solubility product of 10−10.45 mol3 1−3 is obtained.
Molecular Constants of Some XY4 Tetrahedral Ions
Authors: Mohan S.
Published: September 2010

The kinetic constants method developed in relation to tetrahedral XY4 molecules(1, 2) resulted in fresh results with respect to force constants and mean amplitudes of vibration of some molecules. Extending this procedure to eighteen ions in this paper, it is found that the kinetic constants method leads to interesting results in these oases as well. The generalized mean square amplitudes and the Bastiansen‐Morino shrinkage effects are also reported in the present investigation.
Molecular Force Field Study of Some XY5Z Type Molecules by Kinetic Constants Method
Authors: Mohan S.
Published: September 2010

All the quadratic potential energy constants of five XY5Z type molecules have been evaluated using Wilson's F–G matrix method, on the basis of a revised set of symmetry coordinates. The kinetic constants, the redundancy constraints and certain simplifying considerations are employed in solving the problem. The values of molecular potential constants, obtained on the basis of kinetic constants are found to be reasonable.
Solution Conformations of Dianemycin, its Sodium Salt and of Lenoremycin‐Na+ (Ro 21‐6150 or A‐130‐A)
Authors: Anteunis Marc J. O. , Rodios Nestor A. , Verhegge Georges
Published: September 2010

Extensive nmdr experiments in the 300 MHz 1H‐nmr spectra of the title compounds in different solvents allows the conformational description of these pseudocyclic ionophores. There is a striking similarity between the present results and the solid state data for the salts. The free acid form of dianemycin possesses in solution the cyclic form wherein the cation is ultimately held in the salt. Stereoscopic views are presented (Figures 9 ‐ 11). The possible role of the sugar‐like moieties is discussed and a mechanism for trapping is tentatively proposed. Both membrane‐active complexones seem rather primitive representatives of the nigericin family, but lenoremycin offers a more sophisticated topography, the extra side‐ring possessing probably a multiple function.
Die Bildung Von 2,2,4‐Tribenzoyl‐5‐Phenyl‐ 1,3‐Oxathiol Aus Dibenzoylmethan Und Thionylchlorid
Authors: Senning Alexander
Published: September 2010

The reaction of dibenzoylmethane with thionyl chloride yields 2,2,4‐tribenzoyl‐5‐phenyl‐1,3‐oxathiole 3 the structure of which was rigorously proven by means of 13C NMR.
Studies on Organophosphorus Compounds XVIII. Oxidation of Tertiary Alicyclic Amines With Elemental Sulfur in Hexamethylphosphoric Triamide (HMPA). Oxidative Rearrangements of Hexahydroazepines and Octahydroazocines to Bis(3‐Pyrrolyl)Polysulfides
Authors: Perregaard J. , Scheibye S. , Meyer H. J. , Thomsen I. , Lawesson S.‐O.
Published: September 2010

By heating (100‐160 °C) N‐alkylsubstituted alicyclic amines, R‐N(CH2) (n = 4, 5, 6), with elemental sulfur in HMPA, oxidation of the amine ring afforded the corresponding thiolactams, 2. Thus N‐benzylthiopyrrolidone, 2a (67%), N‐(2‐phenylethyl)‐2‐thiopyrrolidone, 2b (71%), N‐benzyl‐2‐thiopiperidone, 2c (27%), N‐(2‐phenylethyl)‐2‐thiopiperidone, 2d (63%), N‐methyl‐e‐thiocaprolactame, 2e (45%), and N‐(2‐phenylethyl)‐e‐thiocaprolactame, 2f (10%) were prepared. From oxidation of N‐alkylhexahydroazepines and N‐alkyloctahydroazocines were produced as the main products bis (1‐alkyl‐2‐ethyl‐3‐pyrrolyl) polysulfides, 3, and bis (1‐alkyl‐2‐(n‐propyl)‐3‐pyrrolyl) polysulfides, 4, respectively. Reduction of these with Zn, HCl or LiAlH4 followed by methylation (MeI) gave the corresponding 3‐(methylthio)‐pyrroles, 8 in 20‐49% overall yields. 1‐(2‐Phenylethyl)‐2‐ethyl‐3‐mercaptopyrrole, 7, was isolated in 48% yield from reduction (Zn, HCl) of the corresponding dipyrrolyl polysulfide. 3, 4‐Dithiolated pyrroles were recognized in most reactions and isolated in some cases. The structures of the pyrroles were established by 1H NMR, 13C NMR, and MS.
Symétrie Moléculaire Dans La Série Des Dibenzyles
Authors: Arte E. , Feneau‐Dupont J. , van Meerssche M. , Gouverneur P. , Mulangala J. Mukinayi
Published: September 2010

Space group and unit cell parameters determinations on seven examples have proved that the crystalline compounds obtained in the formation of C6H5‐CRR'‐CRR'‐C6H5 derivatives from C6H5‐CHRR', are the “meso” centro‐symmetric isomers.
Redétermination De La Structure Du Diphényl‐2, 3 Butane, Forme Meso
Authors: Arte E. , Feneau‐Dupont J. , Declercq J. P. , Germain G. , van Meerssche M.
Published: September 2010

The interpretation of tridimensional diffraction data shows definitely that the investigated structure belongs to the meso form. The molecular centrosymmetry predicted by space group determination is not a statistical effect despite of the orientational disorder observed in the crystal.
Sur La Localisation Des Orbitales Moléculaires En Couches Ouvertes
Authors: Peeters D. , Leroy G.
Published: September 2010

The use of localized molecular orbitals for open shell systems is examined. Preliminary computations on carbon, nitrogen oxygen and fluorine atoms, and on the molecules of CH, NO and O2 are performed. The results obtained are described in terms of hybrids for atoms and lone pairs and bonds for molecules.
Mossbauer Spectroscopy as a Tool for the Investigation of Industrial Iron Ore Sinters
Authors: De Sitter J. , Govaert A. , De Grave E. , Chambaere D.
Published: September 2010

Mössbauer spectroscopy has been used to study the mineralogical composition of an industrial iron ore sinter. Besides a structural study of the different phases, quantitative information on the distribution of iron among the different phases is obtained.
Reactions of N‐l‐(2, 2, 2‐Trichloroethylidene)t. Butylamine With Nucleophilic Reagents
Authors: Verhé R. , De Kimpe N. , De Buyck L. , Tilley M. , Schamp N.
Published: September 2010

Reaction of N‐l‐(2, 2, 2‐trichloroethylidene) t. butylamine with sodium alkoxides and phenoxide in methanol mainly gave the corresponding dichloroimidates, while reaction with potassium cyanide afforded a dichlorocyanoenamine. The reaction mechanisms are discussed.
Determination of Rotational Temperatures in a Transitional Type Hollow Cathode Glow Discharge
Authors: Broekaert J. A. C.
Published: September 2010

Rotational temperatures were measured in a transitional type hollow cathode, operating at 60 ‐ 150 mA discharge current under 260 ‐ 1060 Pa helium or argon pressure. A method using rotational lines in the 2Σ ‐ 2Σ (0, 0) CN 3883 Å band and the 2Σ ‐ 2Σ (0, 0) N+2 3914 Å band, is described. The dependence of measured rotational temperatures (800 ‐ 1700°K) on gas pressure, discharge current and cathode temperature is discussed.
Tautomérie D'Imidazoline‐5‐Thiones
Authors: Maquestiau A. , van Haverbeke Y. , Vanovervelt J.‐C. , Lambert M. , Ravach A.
Published: September 2010

The tautomeric behaviour of various imidazolin‐5‐thiones is examined. In the 2,2,4‐trisubstituted series, the thiocarbonyl NH form constitutes the lone tautomer observed in all types of solvents.

For the 2,4,4‐trisubstituted compounds, the predominant isomer exists in the 1‐NH form and is accompagnied in most cases by a minor percentage of the 3‐NH protomer.

It seems that the composition of the prototropic equilibrium CS ⇋C‐SH in five membered heterocycles depends highly on the nature of neighbouring atoms or groups.
Le désétamage du fer‐blanc par les halogénures organiques
Authors: Mahieu B. , Delplanque P. , Apers D.
Published: September 2010

A new route has been investigated to convert used tinplate into valuable derivatives. Detinning of tin cans by organic halides may provide attractive organometallic compounds in addition to high grade steel scrap. In this work, benzyl chloride is used as reagent in a variety of solvents.
Ring Conformational Aspects of Proline and Hydroxyproline. High Conformational Purity of Pro in DKP's and Hydantoïns.
Authors: Anteunis Marc J.O. , Callens Roland , Asher Vikram , Sleeckx Jozef
Published: September 2010

1H‐nmr literature data for Pro and trans‐Hyp peptides (acyclic and cyclic) are reviewed and complemented with data including some new compounds (diketopiperazines and hydantoins). In both acyclic and cyclic derivatives, the hydroxy proline ring possesses a unique and highly homogenous conformation λ−or λEform) which is gradually changed into a‐form when ø‐values become for L‐residues more negative than ‐40°. Correspondingly, the Pro ring possesses more flexibility especially in the acyclic derivatives where an admixture of different forms is present. The situation becomes biased in cyclic derivatives, although the intrinsically higher mobility of the ring prevails somewhat when compared to Hyp. Also the nature of the major populations in the pseudorotational path of the five‐membered ring is somewhat more sensitive in Pro towards changes in ø. Thus, for ø ∼O° mainly a libration in theßE‐γEregion is present, while theγE form becomes the major one when ø ∼ −40° (L‐residues). For still lower values of ø the pseudorotational phase angle is displaced resulting in aαE form for ø ∼ −100° as the extreme limit. Relative shifts in the1H nmr spectra for the methylene ring protons may serve as a qualitative estimation of the buckle of DKP‐rings and therefore also for cis‐trans assignments. The shift anisotropy caused by the unique orientation of the aromatic side chain in c/D‐Phe‐L‐Pro/ corroborates the findings for the ring conformations of both the flattened DKP‐boat and of the γ−‐form of Pro.
Molecular vibrational analysis of tetramethyl compounds of fourth group elements
Authors: Kalia (Miss) Rama , Dixit Lalji , Gupta P. L.
Published: September 2010

The nature of molecular vibrations has been analysed for (CH3)4 M compounds, MC, Si, Ge, Sn and Pb, using recent Raman/IR data and group theoretical approach. The forms of F2‐vibrations have been discussed using the properties of L− matrices and experimental Coriolis coupling constant data. The overall force field available so far, has been critically analysed following Isotoni's criterion. The results have also been discussed in the light of kinematic coupling (T = G3 4/√det/G/), vibrational constants of tetrahedral molecules, (M‐C) bonding and compliance constants. It has been observed that for tetramethyl compounds with lighter central mass (M), any approximation method would give less satisfactory results due to excessive kinematic coupling and hence for neo‐pentane the “point‐mass model” is less valid.
1H‐NMR of pimaricin at 300 MHZ.
Authors: De Bruyn André , Anteunis Marc J. O. , Verhegge Georges
Published: September 2010

The1H‐nmr spectrum of pimaricin has been obtained in trideuterotrifluoroethanol at 300 MHz. Moderate resolution did not allow to extract all of the spin coupling values however. The glycoside mycosamine occurs in a4C1conformation. The oxirane moiety at C‐4′/C‐5′ is trans substituted.
1H‐NMR spectral study of chlorinated derivatives of the norbornane system. Rotameric Preference of an Endo CH2X Group.
Authors: van Bree Jan , Anteunis Marc J.O.
Published: September 2010

The 1H‐NMR spectra of a series of chlorinated norbornene and derived norbornanone and norbornane systems have been recorded and analysed. Several characteristics of the observed spectral parameters can be explained by considering the rotameric behaviour of the endo‐CH2X group that shows a preference for a conformation with the C‐X bond synclinal to the methine proton of the carbon it is attached to.
Rearrangement of chlorinated β‐diketone monomethyl enol ethers with sodium methoxide
Authors: Verhé Roland , De Buyck Laurent , De Kimpe Norbert , De Rooze Antoine , Schamp Niceas
Published: September 2010

Reaction of the monomethyl enol ethers of 3‐chloro‐2,4‐pentanedione and 2‐chloro‐1‐phenyl‐1,3‐butanedione with sodium methoxide in methanol gave hydroxy enol ethers, respectively 3‐hydroxy‐2,4,4‐trimethoxy‐1‐pentene and 3‐hydroxy‐2,4,4‐trimethoxy‐4‐phenyl‐1‐butene. The reaction mechanism involving the formation and opening of an oxirane predominates the Favorskii‐rearrangement.
Calcul théorique des constantes diélectriques de benzoates de 1H, 1H, perfluoroalkyle
Authors: Leroy G. , Mengoni H. , Raviart A. , Wilante C.
Published: September 2010

In this work, we have calculated dipole moments of a series of fluoroesters by means of the CNDO method.

Onsager's relation allowed us to evaluate the corresponding dielectric constants. The correlation between experimental and theoretical results is rather good.
Conformational study on 2‐oxa‐bicyclo[3.3.0]octan‐3‐ones. configurational assignments in carbocyclic five‐membered rings by1H‐NMR.
Authors: De Bruyn André , van Audenhove Martine , Anteunis Marc J.O.
Published: September 2010

It has been possible to extract at 300 MHz all the1H‐nmr parameters of a series of 2‐oxabicyclo[3.3.0]octan‐3‐ones. Consideration of all the vicinal coupling constants allows to assess their conformation and shows the utility of annelation for five‐membered rings to affect the spectral pecularities in a way to give access to configurational and conformational details.