bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solubility of Alcohols, Phenols and Anilines in Water
Authors: Huyskens Pierre , Mullens Jules , Gomez Alfredo , Tack Joris 
Published: September 2010

AbstractAn 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

AbstractThe 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

Abstract1H‐(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

AbstractA 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

AbstractLes 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

AbstractExtended 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

AbstractN‐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

AbstractFor 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

AbstractA 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

AbstractThe 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.
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

Abstract3‐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

AbstractOrganotin 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

AbstractTwo 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

AbstractThe 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

AbstractBand 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

AbstractDensities 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

AbstractAir 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

AbstractComplete 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

AbstractFour 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

AbstractThe 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

AbstractRaman 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractElectrocatalytic 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

AbstractIn 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

AbstractThe 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.
Preparation of (substituted) 3,3‐dimethyl‐3‐sila‐1‐heterocyclohexanes
Authors: Dedeyne Raymond , Anteunis Marc J. O. 
Published: September 2010

AbstractThe 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

AbstractSeveral 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

AbstractRefractive 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

AbstractDuring 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

AbstractNous 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

AbstractThe 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

AbstractZinc 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.