bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Shift Reagent with MTPA Derivatives in 19F NMR Spectroscopy: Determination of Absolute Configuration of Stereomeric 2‐ and 3‐ Substituted Cyclohexanols
Authors: Merckx E. M. , Van De Wal A. J. , Lepoivre J. A. , Alderweireldt F. C. 
Published: September 2010

AbstractThe relative magnitude of the lanthanide induced shift (LIS) by Eu(fod)3 for the 19F NMR spectra of the CF3 group of diastereomeric (R)‐(+)‐α‐methoxy‐α‐trifluoro methylphenylacetate esters [(R)‐(+)‐MTPA esters] of stereomeric 2‐ and 3‐ substituted cyclohexanols have been measured. The [R,R] diastereomeric esters are responsible for the largest downfield LIS value in the presence of Eu(fod)3. With a well defined Eu (fod)3/ester molar ratio, the opitcal purity can also be determined.
Cyclic voltammetric study of the system Sb(III)/Sb(Hg) IN 4 M HCl
Authors: Verplaetse H. , Donche H. , Temmerman E. 
Published: September 2010

AbstractThe system Sb(III)/Sb(0) has been investigated in 4 M HCl by cyclic voltammetry at a sitting mercury drop electrode. It was found that specific adsorption of the reactant Sb(III) occurs. This was confirmed by droptime measurements at a dropping mercury electrode. Other deviating features of the cyclic voltammetric curves can be explained by the convergent nature of the diffusion process within a spherical mercury electrode.
Conductivity and photoconductivity of TCNQ salts of poly (1‐butyl‐2‐vinyl‐pyridinium)/polystyrene copolymer.
Authors: Wollast P. , Noirhomme B. , Vander Donckt E. 
Published: September 2010

AbstractThe dark conductivity of the tetracyanoquinodimethane (TCNQ) salt of poly (1‐butyl‐2‐vinylpyridinium)/polystyrene copolymer in the presence of various amounts of neutral TCNQ has been measured using the four‐point probe technique. The activation energy to electrical conduction is obtained between +2 and +35°C. The quantum yield of carrier collection under irradiation at 360‐370 nm is 10−2. It appears that the samples examined are not suitable for light into electricity conversion: to decrease the resistivity of the films, large quantities of neutral TCNQ have to be added to the polymer which has for effect to decrease the apparent band gap of the material to values much smaller than the ideal value (1,2‐1.5 eV).
Electronic structure of dimethyl disulfide and naphthalene 1,8‐disulfide: Ab initio and E.S.C.A. results
Authors: Riga Joseph , Verbist Jacques J. , Lamotte Christian , Andre Jean‐Marie 
Published: September 2010

AbstractThe electronic structure of dimethyl disulfide and naphthalene 1,8‐disulfide has been investigated by means of ab initio calculations. Theoretical results are compared with high resolution ESCA valence band spectrum of solid dimethyl disulfide. Semiconducting properties are predicted for planar aromatic disulfides.
A Proposal of a mechanism for ring inversion in all‐cis‐transoid‐perhydropolycenes, including cis‐decalin and cis‐transoid‐cis‐perhydroanthracene.
Authors: De Pessemier Fritz , Anteunis Marc , Tavernier Dirk 
Published: September 2010

AbstractA mechanism for ring inversion in the title compounds is discussed. Activation enthalpies are predicted to be 13.4 kcal.mole−1 for the decalin and the perhydroanthracene, and 17.4 kcal.mole−1 for the perhydropolycenes, independent of the number of annelated rings.
Kinetics of the reaction of calcium sulfite with SO2
Authors: van Houte G. , Delmon B. 
Published: September 2010

AbstractThe kinetics of the reaction of CaSO3 with SO2 have been investigated in the temperature range 450–640°C. The reaction corresponds to the model of uniform attack of the reactant surface. Initial rates correspond to a control by interface chemical processes; activation energy is 30 Kcal. mol; the reaction is first order with respect to SO2. Diffusion, presumably solid state diffusion through the covering sulfate layer, progressively becomes strongly rate‐limiting, but the reaction can be conducted to completion.
Electrocatalytic reduction of butanone II. kinetics of the production of butanol 2
Authors: Feyaerts K. , De Hemptinne X. 
Published: September 2010

AbstractBy using a square wave modulation technique, a fast reversible step is isolated ahead of the rate determining process for the reduction of butanone to butanol‐2.By comparison with analogous results obtained previously for the reduction of acetone to propane, it is concluded that this reversible step is situated ahead of the branching between the alcane and alcohol paths.
The structure of trocheliophorol, a cembranoid diterpene from soft corals of the genus SARCOPHYTON(1).
Authors: Groweiss A. , Kashman Y. , Vanderah D. J. , Tursch B. , Cornet P. , Braekman J. C. , Daloze D. 
Published: September 2010

AbstractThe structure determination of trocheliophorol (1), a new cembrans diterpene isolated from two soft corals of the genus Sarcophyton, is described.
Étude Par Spectrométrie de Vibration, de L'Interaction Entre Les Halogénures de Trialkylammonium et Quelques Dérivés Phénoliques. II. Vibration vNH+
Authors: Rulinda J. B. , Zeegers‐Huyskens T. H. 
Published: September 2010

AbstractThe vibrational spectrum of Et3NH+ Cl− and Et3 N H+ Br− has been examined in the v NH+ range. In the solid state, the Raman spectrum shows a well‐defined doublet while the infrared band profile is very large and shows a resonance window fixed at 2510 cm−1. The same effect is observed for both salts dissolved in 1,2 dichloroethane. The formation of hydrogen bonded complexes between the anions Cl− or Br− and some phenol derivatives brings about a frequency shift of the vNH+ band toward higher wavenumbers. This shift depends on the acidity of the phenol derivative and on its concentration. For these complexes, a window also appears at 2510 cm−1; this negative absorption probably arises from a Fermi resonance with the rocking vibration of the methyl group.
Ideal Gas Thermodynamic Functions of Some Mixed Halides of Boron
Authors: Adame I. Ernesto , Vicharelli Pablo A. 
Published: September 2010

AbstractThe moments of inertia of 10 BF2 Br, 11 BF2 Br, 10 BFBr2, 10 BCl2Br, 11 BCl2Br, 10BClBr2, and 11 BClBr2, and 11 BClBr2 have been revised. The present values and the available vibrational data have been utilized to reevaluate the ideal gas chemical thermodynamic functions of these molecules for the temperature range 100 to 2000 K. A rigid rotor and harmonic oscillator model has been used.
Study of the Decomposition Products Formed from Trans Ferulic Acid by Treatment with Boiling Hydrochloric Acid
Authors: van Brussel W. , Tavernier D. , van Sumere C. F. 
Published: September 2010

AbstractPrevious experiments showed the instability of hydroxycinnamic acids (e.g. ferulic acid) in acid media. In order to study this problem, which is of great importance for the analysis of naturally occurring hydroxycinnamic acid derivatives, more thoroughly, ferulic acid was treated on a preparative scale with boiling hydrochloric acid and the decomposition products obtained were separated and identified.
On the Structure of Tricyclodehydroisohumulone
Authors: De Taeye Leo , De Keukeleire Denis , De Bruyn André , Verzele Maurice 
Published: September 2010

AbstractThe structure of tricyclodehydroisohumulone was investigated by 300 MHz 1H‐NMR and other spectroscopic methods. It is either 3‐(3‐methylbutanoyl)‐10‐(1‐methylethenyl)‐4,5‐dihydroxy‐9,9‐dimethyl‐tricyclo [6.3.0.01,5]undec‐3‐ene‐2,6‐dione or 3‐(3‐methylbutanoyl)‐9‐(1‐methylethenyl)‐4,5‐dihydroxy‐11,11‐dimethyl‐tricyclo[6.2.1.01,5]undec‐3‐ene‐2,6‐dione. Other criteria lead to a preference for the first structure.
Chemical Studies of Marine Invertebrates. XXXV(1). Sarcoglaucol, a Novel Cembrane Diterpene from the Soft Coral Sarcophyton Glaucum (Coelenterata, Octocorallia)(2)
Authors: Albericci M. , Braekman J. C. , Daloze D. , Tursch B. , Declercq J. P. , Germain G. , van Meerssche M. 
Published: September 2010

AbstractSarcoglaucol (1), a novel, ichtyotoxic cembrane diterpene has been isolated from the alcyonarian Sarcophyton glaucum. Its structure and relative configuration were determined by X‐ray diffraction analysis.
Determination de la Structure de la N,N‐Diethylbenzamide‐Oxime
Authors: Arte E. , Declerq J. P. , Germain G. , van Meerssche M. 
Published: September 2010

AbstractThe structure of the title compound has been investigated in order to determine the configuration of the oxime group. The molecules appear to be in the E configuration and are H‐bonded to form dimers in the crystal.From partial structural informations, p‐nitrobenzamidoxim seems to adopt the Z configuration.
Steric hindrance in N‐substituted benzyl, N‐T‐butyl nitroxides
Authors: De Pauw E. , Collin J. E. 
Published: September 2010

AbstractThe EPR spectra of N‐substituted benzyl N‐t‐butyl nitroxides show a significant dependence of the β‐CH2 proton hyperfine coupling constants on the position and the number of phenyl substituents. This behaviour may be explained by simple steric considerations.
The reaction of ethyl 4‐bromo‐2‐ethoxycarbonyl‐2 pentenoate with some nucleophiles
Authors: Kristensen J. , Lawesson S. ‐O. 
Published: September 2010

AbstractThe title compound, III, has been reacted with sodium phenylthiolate and morpholine and the substitution products IV and V respectively, have been isolated. No Michael addition was observed. Potassium cyanide and NaBH4 do react with III according to Michael and subsequent ring‐closure reactions lead to the cyclopropanes VI and VII, respectively. Sodium ethoxide and III are also suggested to undergo a Michael addition, followed by a cyclization reaction and finally an opening of the ring by the ethoxide ion to give the acetal VIII.
Preparation and some reactions of N,N‐diacetylamines
Authors: Meyer H. J. , Nolde C. , Thomsen I. , Lawesson S. ‐O. 
Published: September 2010

AbstractA number of N,N‐diacetylamines has been prepared in generally high yields by acetylation of primary amines with acetic anhydride in presence of magnesium and catalytic amounts of Cu(OAc)2. The general physical and also some chemical properties of N,N‐diacetylamines are presented together with pertinent spectroscopic data.
Molecular constants of Trimethyl Antimony (V) Dihalides
Authors: Namasivayam R. , Viswanathan S. 
Published: September 2010

AbstractThe force field study of Me3SbX2 (X=F, Cl, Br, I) molecules of D3h symmetry has been carried out by Redington's approach treating the methyl group as point masses. The force constants, mean amplitudes of vibration, bond charge and path length parameters and rotation distortion constants have also been calculated and compared with the literature values whichever is available.
Distribution of Electrolytes Over Two Liquid Phases
Authors: Joos P. , Verburgh Y. 
Published: September 2010

AbstractThe partition coefficients and the distribution potentials of electrolytes for distribution over two phases (water and nitrobenzene) are examined theoretically. Measurements are presented for a homologous series and compared with theoretical predictions. Also the distribution of an ionic mixture R+, P+ (cations) and X−, Y− (anions) is considered. A relation is found between the distribution potentials of the electrolytes RX and PY at one hand and of the electrolytes RY and PX at the other hand.
Étude de L'Autoassociation de Quelques α‐Hydroxyiminocétones en Solution Par Spectroscopie Infrarouge et Mesures Diĺectriques.
Authors: Bernadou J. , Fayet J. P. , Bonnafous M. , Mauret P. 
Published: September 2010

AbstractFive α‐hydroxyiminocétones R‐CO‐C(NOH)‐R' have been studied in CCl4 dilute solution. Frequency and intensity variation of infrared absorption bands (C0 and 0‐H) and dielectric permittivity variation, at several concentrations, point out formation of intra or intermolecular hydrogen bonds, involving or not the CO group; this show existence of monomer (RR'camphor ring, syn isomer) and three different associations: closed dimer (RR'camphor ring, anti isomer), open polymers (RCH3, R'H) and (RR'CH3) or (RR'C6H5).
Additional Evidence for the Existence of Only One Kind of Transition State in the NABH4 Reduction of Aliphatic Ketones
Authors: Lemière G. L. , van Osselaer T. A. , Alderweireldt F. C. 
Published: September 2010

AbstractOnly one isokinetic relation is found for the NaBH4 reduction of aliphatic ketones. The study includes acyclic and cyclic ketones, hindered and unhindered cyclohexanones, overall reaction rates and reaction rates of axial and equatorial attack on cyclohexanones. This strongly supports the view‐point that all these reactions proceed through only one kind of transition state. For aromatic ketones other correlations are found corresponding with other types of transition state.
Synthesis and conformational features of a series of benzyl 4‐O‐(aldopentopyranosyl)‐2,3‐anhydro‐β‐D‐ribopyranosides.
Authors: De Bruyn AndrÉ , Rijsbergen Ronan Van , Anteunis Marc J. O. , Claeyssens Marc , Deleyn FranÇOis 
Published: September 2010

AbstractA series of benzyl 4‐0‐(aldopentopyranosyl)‐2,3‐anhydro‐β‐D‐ribopyranosides has been synthesized. The 1H‐nmr parameters of these compounds have been obtained at 300 MHz in pyridine‐d5 solution. Chemical shift increments of pyranoid systems in pyridine solution are advanced. The conformation of the 2,3‐anhydro‐β‐D‐ribopyranoside moiety is discussed. It occurs in a nearly equi‐energetic equilibrium of the 0H5 and 5H0 forms.
Raman Intensity Study of the VC=O Band of Cyclohexanone Complexed with Phenol Derivatives
Authors: Thijs C. , Zeegers‐Huyskens T. H. 
Published: September 2010

AbstractThe absolute Raman intensity of the VC=O band of cyclohexanone complexed with phenol derivatives increases by complex formation. The intensification factor varies between 1.16 (3,4‐diCH3 phenol) and 1.78 (3,4,5‐triCl phenol) and is proportional to the enthalpy of complex formation. The intensity enhancement cannot be explained by the variation of bond order or distance of the C=O bond but is discussed in terms of the Orville‐Thomas pulsed cloud model.
Contribution a L'Étude Théorique Des Complexes Par Liaison Hydrogène. VI. Le CH4 Comme Donneur de Proton.
Authors: Ruelle P. , Leroy G. , Louterman‐Leloup G. 
Published: September 2010

AbstractAb initio study of molecular complexes including methane as proton donor has been carried out at the 4‐31G basis set level with the GAUSSIAN‐70 computer program. The geometry optimization as well the energy decomposition analysis and the configuration interaction calculations allow us to show the presence of weak hydrogen bonds in these systems.
Cycloaddition Reactions of Tris (IMINO) Thietanes
Authors: L'abbé Gerrit , Huybrechts Lucas , Toppet Suzanne , Declercq Jean‐Paul , Germain Gabriel , Meerssche Maurice Van 
Published: September 2010

AbstractTris (imino) thietanes undergo ring transformations with electron‐rich unsaturated systems. For instance, 1a,b react with trans‐β‐dimethylamino styrene to yield tetrasubstituted pyrroles 2a,b which can be smoothly thermolyzed into trisubstituted pyrroles 3a,b and tert‐butyl isothiocyanate. With ynamines, exemplified by N‐diethylaminopropyne, 1a‐c are transformed into thiopyrans 4a‐c, and thence into thiophenes 5a‐c by elimination of tert‐butyl isonitrile. The products were identified by spectral (IR, 1H NMR, 13C NMR, mass spectra) and analytical properties as well as by X‐ray analyses.
Pd(II) Complexes with N‐Methyl Thiobenzamide
Authors: Aarts A. J. , Desseyn H. O. , Herman M. A. 
Published: September 2010

AbstractComplexes of Pd(II) with N‐methylthiobenzamide (L) are investigated by infrared spectroscopy. Compounds prepared are cis‐PdL2‐X2. (X=Cl or Br), trans‐PdL2I2. and [PdL4] X2 (X=Cl, Br or ClO4). The ν(PdX) and ν(PdS) frequencies are discussed. The high trans‐effect of L is demonstrated by its influence on the structure and on the spectroscopic properties.
Substitution of Metal Ions in Anionic Surfactants by Ion‐Exchange Reactions in Non‐Aqueous Solvents
Authors: Nelen A. A. M. , Tavernier S. M. F. , Gijbels R. 
Published: September 2010

AbstractThe preparation of anionic surfactants with different metal counter ions has attracted some interest in recent years. Up to now basic neutralisation of the hydrogen form of the surfactant was used. A new method is described, which is based on ion‐exchange reactions accompanied by precipitation in non‐aqueous solvents such as ethanol or diethylether. The purity of the surfactants formed is better than 98% and the yield is higher than 92%.
Stereochemical Aspects of Proton Chemical Shifts. IX. Influence of O‐Alkyl Groups on the Chemical Shift of the Glycosidic Proton in Pyranoid Systems
Authors: Bruyn André de , Hosten Noël , Anteunis Marc J. O. , Claeyssens Marc , De Bruyne Clement K. 
Published: September 2010

AbstractThe 1H NMR parameters of some alkyl β‐D‐xylopyranosides (alkyl = Me, Et, n.Pr, i.Pr and t.Bu) have been measured in D2O and DMSO‐d6 solution at 300 and 360 MHz. A rationale is checked to explain the influence of the 0‐alkyl groups on the chemical shift of the glycosidic proton. It is found, as reported previously for other cases1, 2, that γ‐increments in full carbon‐skeleton are very similar to those in a H‐C‐O‐C‐C skeleton.
Assignment of Fundamental Vibrations of Hydrazo Derivatives. Carbohydrazide and Diprotonated Carbohydrazide
Authors: Sathyanarayana D. N. , Raja S. V. Kasmir , Savariraj G. A. 
Published: September 2010

AbstractThe Infrared spectra of carbohydrazide, diprotonated carbohydrazide and their deuterated compounds have been measured in the solid state. From the results on thio‐ and selenocarbohydrazides and other related molecules and normal coordinate analyses using a Urey‐Bradley force field assignments of the fundamental vibrational frequencies and a description of the normal modes of carbohydrazide, diprotonated carbohydrazide and their deuterated species are given.
Kinetics of the Reaction of CaSO3 and CaCO3 with SO2 in the Presence of CaCl2
Authors: van Houte G. , Delmon B. 
Published: September 2010

AbstractWe report kinetic data on the reaction of CaCO3, and CaSO3 impregnate with 2% mol. CaCl2, at various temperatures between 450 and 640° C. The rate of reaction of CaCO3, with SO2, giving CaSO3, is greatly increased in comparison with pure CaCO3. An important increase of the surface area of the reacting solid is observed in the initial stages of the reaction. The initial rates of reaction correspond to a thermal increment of 37 kcal.mol−1. Order with respect to SO2 is 1. The rate of reaction of treated CaSO3 with SO2 is drastically reduced, in comparison to pure CaSO3, Possible mechanisms of the action of CaCl2 are discussed.
Infrared Study of the Addition Compound Between Benzamide and Tintetrabromide in Solution
Authors: Cauteren‐Thevissen Mady Van , Huyskens‐Zeegers Thérèse 
Published: September 2010

AbstractThe stability constants K1 and K2 of the molecular adduct between benzamide and tintetrabromide in chloroform as solvent can be determined only for very dilute solutions because, as suggested by the study of the ν(C=0) and the ν(NH2) vibrations, the formation of this adduct induces the selfassociation of the amide molecule.
Structures des Phényl‐5 et Éthyl‐5 Diméthyl‐2,2 Dioxanne‐1,3 Dione‐4,6
Authors: van Coppernolle A. , Declercq J. P. , Dereppe J. M. , Germain G. , van Meerssche M. 
Published: September 2010

AbstractThe crystal and molecular structures of two 5‐R derivatives of the 2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione with R = C6H5 or C2H5 were determined by X‐ray diffraction and compared with a previous determination of the 5‐thienyl compound. The crystal data are as follow:R = C6H5: 2,2‐dimethyl‐5‐phenyl‐1,3‐dioxane‐4,6‐dione; C12H12O4, monoclinic, P21/n, a = 5.255(1), b = 13.786(4), c = 15.484(7) Å, β = 94.34(3)°, V = 1118.5(7)å3, Dx = 1.31 g cm−3, Z = 4.R = C2H5: 5‐ethyl‐2,2‐dimethyl‐1, 3‐dioxane‐4,6‐dione; C8H12O4, orthorhombic, P212121, a = 5.196(1), b = 10.908(4), c = 15.925(6)Å, V = 902.7(5)A3 Dx = 1.27 g cm−3, Z = 4.The structures have been solved by direct methods (MULTAN) and refined by least squares. In both compounds, the dioxanedione ring is in a boat conformation and the molecules exhibit non‐crystallographic mirror symmetry.
Intramolecular Exciplex Formation in α‐N‐Dialkylamino‐ω‐Arylalkanes
Authors: Vanderauweraer M. , De Schryver F. C. , Gilbert A. , Wilson S. 
Published: September 2010

AbstractThe temperature and solvent dependence of the photophysical behaviour of 3‐phenyl‐1‐N‐dimethyl‐aminopropane and 4‐phenyl‐1‐N‐dimethylaminobutane are investigated. The formation of a polar excited state complex is shown to be thermodynamically controlled.
Ring‐Opening Reactions of Tris(Imino)Thietanes
Authors: L'abbé Gerrit , Huybrechts Lucas , Toppet Suzanne , Declercq Jean‐Paul , Germain Gabriel , van Meerssche Maurice 
Published: September 2010

AbstractTris(imino)thietanes (1a‐c) manifest a dual reactivity in ring‐opening reactions. Methanol, diethylamine and ethanethiol all attack the thietane ring at the electrophilic C4‐atom to yield open‐chain products of type 2‐4. On the other hand, the reactions of 1a‐c with hydrazoic acid occur with cleavage of the C2‐S bond producing tetrazoles of type 6. Sodium azide and 1a reacted to furnish the unexpected product 9. Product characterization was based on spectral (IR, 1H NMR, 13C NMR, mass spectra) and analytical properties, and also, in the cases of 6b and 9, on an X‐ray diffraction analysis.
Some Aspects of Steroid Research Based on Natural Products from Plant Origin
Authors: Crabbé Pierre 
Published: September 2010

AbstractA short report on the use of diosgenin as a starting material for the preparation of a number of steroids is given. The synthesis of several steroid hormones is briefly described. Historical aspects of the chemical synthesis and clinical studies of steroidal contraceptive agents are also mentioned. Some human facets of research in the steroid field are outlined.
Détermination de la Matrice des Coordonnées de Symétrie Pour un Groupement XYn Matrices U, G, F ET Σ Pour les Molécules XY6 de Symétrie D3h
Authors: Mahmoudi Saâd , Wendling Edgar 
Published: September 2010

AbstractIn order to compute later all the force constants and mean‐square amplitudes of the generalized valence force field, we are proposing a method for the determination of the U‐matrix for XYn groups, and the U‐, G‐, F‐ and Σ matrices (Wilson's Method) for XY6, (D3h ) molecules.
The theoretical study of (2 + 2) cycloadditions ‐ the concerted ethylene dimerizations reaction
Authors: Burke Luke A. , Leroy Georges 
Published: September 2010

AbstractThe (2s + 2a) path for the dimerization of ethylene is found to be high energy valley leading into the (2s+2s) path just after this latter's transition state. A minimal basis set (STO‐3G) ab initio method is employed and supplemented by either a 15 or 55 configuration interaction. The (2s+2a) barrier is found to be 109 (107) kcal/mole with 15 (55) configurations as opposed to 82.5 (82.3) kcal/mole for the (2s+2s) barrier. This is to be compared to the two‐step barrier of 42.4 kcal/mole previously found with STO‐3G and 15 configurations.It is found that four cis‐substituted ethylenes serving as the antarafacial partners reduce the (2s+2a) barrier as the substituents become stronger electron donors or acceptors. Conversely, the (2s+2s) barrier rises with the strength of the substituent.