bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intensity Study of the νOH Stretching Vibration in Some Complexes of Phenols With N, N‐Dimethyl‐2‐Amino‐3‐Dimethyl‐1‐Azirine
Authors: Vaes J. , Zeegers‐Huyskens Th. 
Published: September 2010

AbstractThe intensity of the νOH stretching vibration has been measured for hydrogen bonded complexes formed by phenol derivatives and N, N‐dimethyl‐2‐amino‐3‐dimethyl‐1‐azirine. In these closely related complexes, the square root of the intensity increment is linearly related with the pKa of the substituted phenol and with the complexation enthalpy.
Chemical Shifts of Aldohexopyranoses Revisited and Application to Gulosylglucose
Authors: De Bruyn André , Anteunis Marc , van Beeumen Jozef 
Published: September 2010

AbstractThe 1H‐nmr data of D‐gulopyranose and D‐altropyranose allowed to suggest new increment rules that can be used to predict the chemical shifts of D‐aldohexapyranoses within a range of ±0.09 ppm. The 1H‐nmr parameters of gulosylglucose are also determined. They suggest the structure of this disaccharide to be β‐D‐gulopyranosyl(1→4)‐D‐glucopyranose.
A Resonance‐Window Effect in the γOH Vibration of Some Hydrogen‐Bonded Complexes
Authors: Zeegers‐Huyskens Th. 
Published: September 2010

AbstractThe broad γOH bands of some substituted phenols (4‐CH3, 4‐F, 4‐Br, 4‐1) complexed with tetramethylurea are characterized by a transmission window at about 690 cm−1. This window is produced by a resonance interaction of the γOH and the ν4 vibrational levels of the same symmetry species.
Solution Conformation of the Ionophore A204A Na+‐Salt
Authors: Anteunis Marc J. O. , Verhegge Georges 
Published: September 2010

AbstractMost of the parameters of the Na+‐salt of A204A could be extracted from its 300 MHz H‐nmr spectrum in CDCl3, by consecutive double irradiation and INDOR experiments. A comparison of the so‐obtained solution conformation (Figure 4) with that reported2 for the solid state disclose their striking analogy. The backbone forms a pseudocyclic structure, closed by head‐to‐tail hydrogen bond between OH‐15 and COOθ (1). The cation is fixed in the center by at least six ligands, forming an irregular octahedron. Rather OH‐3 or 0‐4 (instead of the second oxygen atom of the carboxylic function as proposed2 for the crystaline state) seems to be involved as one of the ligands. Also, the rotameric states of some side chains (methoxy groupings and ring G) behave presumably different in solution. The outside periphery of the pseudo cycle is not entirely hydrophobic and four methoxy groups, OH‐15 and at least three ether/acetal oxygen atoms point away from the central cavity into the surroundings. Most of these ambident functions are concentrate around one region, e. g. the dangling sugar‐like ring G. This is a chemically mobile entity and attached via an acetal function to the remaining architecture, the latter thus being the sole skeleton responsible for chelation.
Chemical Applications of Arc Plasma Techniques. The Thermal Decomposition of Molybdenite
Authors: De Vynck I. A. 
Published: September 2010

AbstractTwo different arc plasma techniques are used for the thermal dissociation at high temperatures of molybdenumdisulfide into metallic molybdenum and elemental sulfur. One plasma technique allows the generation of a plasma flame characterised by a large section, a small directed velocity and a less steep radial temperature profile as compared to a plasma jet generated by a classical plasmatorch. The other plasma technique make use of the so called transferred arc procedure.Both methods allow the production of a high purity grade molybdenum metal but as far as the energy is concerned a combination of the two techniques in a two step procedure seems to be preferable.
Benzo‐ and Indoloquinolizines XIV The Conformational Equilibrium in the Rel‐(4bα, 8aα, 15bα)‐ 4b, 5, 6, 7, 8, 8a, 10, 11‐Octahydro‐15bH‐Isoquino [2, 1‐f] Phenanthridine Isomer
Authors: Tourwé D. , Vandersteen L. , van Binst G. 
Published: September 2010

AbstractThe observation of all the signals of the two conformers in the low temperature 13C NMR spectrum of the rel‐(4bα, 8aα, 15bα)‐ 4b, 5, 6, 7, 8, 8a, 10, 11‐octahydro‐15bH‐isoquino [2, 1‐f] phenanthridine isomer, allowed a reassignment of the conformational equilibrium. The two conformers have either a boat conformation of the B ring, or of the C ring.
Enethiols X. About 2‐Mercapto‐Cinnamic Acids
Authors: Jensen L. , Thomsen I. , Lawesson S.‐O. 
Published: September 2010

AbstractReaction of 5‐arylidene‐3‐methyl‐rhodanine and 4‐benzylidene‐1, 3‐oxathiolan‐ 5‐on with alcoholates yields esters of 2‐mercapto‐cinnamic acids. Reaction of 4‐benzylidene‐1, 3‐oxathiolan‐5‐on with primary amines gives 5‐benzylidene‐3‐alkyl‐4‐thiazolones except for methylamine which yields N‐methyl 2‐mercapto‐cinnamamide. Some derivatives (amides, ester, thioester) of 2‐methylthiocinnamic acid have been prepared.
Étude De La Structure Moléculaire De L'oxacilline Et De L‚Acide Penicilloique Correspondant
Authors: Blanpain P. , Laurent G. , Durant F. 
Published: September 2010

AbstractThe crystal structures of (5‐methyl‐3‐phenyl‐4‐isoxazolyl) penicillin monohydrate (I) and of the methyl diester of the corresponding penicilloic acid (II) were solved from X‐Ray diffraction by direct methods and refined to R = 0.043 and 0.087 respectively. Bond distances and angles of I agree with those of other penicillin derivatives. The side‐chains of molecules I and II have the same conformation.
Tri‐ and Tetrasubstituted Alkenes: Synthesis and Assignment of 3,4‐Diethylhexene‐2
Authors: De Valck Anny , Geise H. J. , Dommisse R. A. , Luyten Y. 
Published: September 2010

AbstractDehydration of 3, 4‐diethylhexanol‐3 by means of oxalic acid yields mainly a mixture of Z and E‐isomers of 3, 4‐diethylhexene‐2. After separation by preparative GLC the identification and configurational assignment was made by 13C and 1H n.m.r.
Correlation Between the Vibrational Properties and the Energy of the Hydrogen Bonds ‐ OH…N and OH…O=C Systems
Authors: Zeegers‐Huyskens Th. 
Published: September 2010

AbstractThe frequency shift and the intensity enhancement of the νOH stretching vibration have been compared for OH…N and for OH…O=C hydrogen bonded systems. It is suggested that the contribution of the charge transfer to the total intensity is higher for OH…N bonds but that the contribution of the induced moment to the intensity is higher for OH…O=C bonds.
New Derivatives of the Alloisohumulones
Authors: De Taeye Leo , De Keukeleire Denis , Verzele Maurice 
Published: September 2010

AbstractFour new compounds, derivatives of the alloisohumulones, have been isolated and identified as: cis‐ and trans‐2‐(3‐methylbutanoyl)‐5‐(3‐methyl‐2‐butenyl)‐3, 4‐dihydroxy‐4‐(Δ2, 3‐epoxy‐4‐hydroxy‐4‐methylpentanoyl)‐2‐cyclopentenone (5 and 6, respectively); 2‐(3‐methylbutanoyl)‐5‐(3‐methyl‐2‐butenyl)‐3, 4‐dihydroxy‐4‐(3‐hydroxy‐4‐methyl‐2‐pentenoyl)‐2‐cyclopentenone (7) and 3′‐(3‐methylbutanoyl)‐5′‐(3‐methyl‐2‐butenyl)‐2′‐hydroxy‐3, 3‐dimethyl‐spiro [5.4]‐2‐oxa‐deca‐2′, 4‐diene‐4′, 5‐dione (8).
Synthesis of Benzoxazepine Derivatives III. Isoindolinones
Authors: Pecher Jacques , Waefelaer Adolphe , Poultier Paul 
Published: September 2010

AbstractThe condensation of 2‐aryloxyalkylamines (1) with 2‐formylbenzoic acid gives substituted aminophthalides (8) which can be isolated in some cases and which cyclize to benzo [a] 1,4‐oxazepino [5,4‐a]isoindoles (11) 2‐(3, 4‐Dimethoxyphenoxy) alkylamines and 2‐formylbenzoic acid give further a second type of cyclization.
Acetoxyéthylation Aromatique Homolytique
Authors: El Zein M. , Gardrat C. , Maillard B. 
Published: September 2010

AbstractAcetoxyethyl radicals, generated by decomposition of di‐t‐butyl peroxide in the presence of 2‐methyl‐1,3‐dioxolane, react with aromatic compounds to give substitution products. From the orientation and relative reactivity data resulting from attack of acetoxyethyl radicals on several monosubstituted benzenes, it is concluded that the radical has a nucleophilic character. Partial rate factors for meta and para positions have been correlated with HAMMETT parameters to give a ρ value of + 0.24.
Regiospecificity in the diels‐alder reaction of 1,2,4‐trichloro‐3,5,5‐trimethoxycyclopentadiene.
Authors: van Bree Jan , Anteunis Marc J.O. 
Published: September 2010

AbstractSome Diels‐Alder adducts of 1,2,4‐trichloro‐3,5,5‐trimethoxycyclopentadiene were prepared and their structure elaborated by chemical transformations. By this it was established that a preferred formation of the 5‐endo‐substituted adducts is found for allyl bromide and allyl acetate, while acrolein yields an excess of the 6‐endo‐isomer.
Synthese de 1‐methyl‐3‐hydroxypyrazolo [3,4‐b] pyridines.
Authors: van Haverbeke Y. , Maquestiau A. , Vanden Eynde J.‐J. 
Published: September 2010

AbstractA number of 1‐R‐3‐hydroxypyrazolo [3,4‐b] pyridines are obtained by cyclocondensation of a 1‐R‐5‐aminopyrazolin‐3‐one with β‐dicarbonyl compounds.The first step of this synthesis involves the most reactive carbonyl group exclusively and, competitively, the 4‐position and the amino function of the pyrazolone.The orientation of the reaction is dependent on the nature of the β‐dicarbonyl precursor.
Les Nitrates Basiques Mixtes de Cuivre et de Cobalt
Authors: Glibert J. , Claes P. 
Published: September 2010

AbstractThe precipitate‐solution equilibrium obtained by the addition soda to 8 mixed solution of Cu(NO3)2Co(NO3)2 ( 0.165 M/1 ) leads by aging 20 or 75°C to the formation of the same solid solutions Cu4−xCOx(OH)6(NO3)2(monoclinic) (xmax.=2) for the high [Cu2+]/[Cu2+] ratios and CoI‐YCUy(OH)2 (hexagonal) (ymax.=O,2) for the low values. A zone of demixtion separates these two compounds. The distribution factor indicates a continuous preferential precipitation of copper but that one is strongly reinforced in the hydroxide phase.
Induction Asymétrique Dans L'Addition Conjuguée D'Organocuprates de Lithium a la Cyclohexenone (1)
Authors: Ghozland Freddy , Luche Jean‐Louis , Crabbé Pierre 
Published: September 2010

AbstractA series of heterocuprates CH3 (RY)CuLi, prepared from mono‐ or bi‐functional chiral inductors, were reacted with cyclohexen‐2 one. Whereas no asymmetric induction was observed in the presence of chiral alcohols, enantiomeric excesses varying from −6 to +15.5% result from the use of amines or aminoalcohols.
Urey‐Bradley Force Field of CF3O−
Authors: So S. P. 
Published: September 2010

AbstractThe normal coordinate analysis of the trifluoromethoxide anion CF3O− in the Urey‐Bradley force field was performed using published vibrational frequencies. The analysis was carried out within Wilson's FG formalism and the force constants were evaluated by a computer program based on the least‐squares fit method. Results show that the bonding of CF3O− is similar to that of NF3O.
High‐Resolution 1H‐NMR Study of Carriomycin Free‐Acid and Its Sodium Salt
Authors: Rodios Nestor A. , Anteunis Marc J. O. 
Published: September 2010

AbstractThe spectroscopic data extracted from the 300 MHz 1H‐nmr of carriomycin (1) and its sodium salt (1) show that in solution both the free acid and Na+‐complex possess solute‐conformations that must be almost identical to the spatial structure previously found in the solid state of the thallium salt1. The backbone in both states, free and salt, forms a pseudocyclic structure closed by hydrogen bonding between the carboxylate fragment and OH‐13. The extra sugar‐like ring G does not participate in the ion trapping. No water molecule participates in the cyclization of carriomycin free acid nor in its salt.The present member of the polyether antibiotics therefore is highly similar to others having a dangling sugar moiety (e.g. A204A4 and septamycin13), in contrast with lenoremycin10 where this sugar fragment does participate in complexation.
Use of shift reagent with mtpa derivatives in 19F NMR spectroscopy: III. Determination of absolute configuration and enantiomeric purity of secondary alcohols
Authors: Van Wal A. J. De , Merckx E. M. , Lemière G. L. , van Osselaer T. A. , Lepoivre J. A. , Alderweireldt F. C. 
Published: September 2010

AbstractThe LIS values produced by Eu(fod)3 for the CF3‐19F NMR signals of the MTPA esters of different stereoisomeric secondary alcohols have been measured. The applicability of these values for assigning the absolute configuration of the alcohols has been studied. The advantages of this method over the corresponding 1H NMR method of Yamaguchi and the limits of both have been investigated. A new model of the Eu(fod)3/MTPA ester complex is given.
Pseudoguaianolides. The total synthesis of (±)‐neoambrosin (±)‐parthenin and (±)‐hymenin
Authors: Kok Pierre , De Clercq Pierre , Vandewalle Maurits 
Published: September 2010

AbstractStarting from an easily obtainable and already described intermediate 2, the total synthesis of three pseudoguaianolides is described. The transformation involves functionalization of the cyclopentane ring.
Synthesis of benzoxazepine derivatives. IV. Anthracenooxazepines
Authors: Pecher Jacques , Waefelaer Adolphe 
Published: September 2010

AbstractThe 3‐(3,4‐dimethoxyphenoxyalkylamino) phthalides (4) cyclize in PPA solution to demethylated and demethoxylated 2,3‐dihydro‐8‐oxo‐anthraceno [9, 9a, 1‐ef] 1,4‐oxazepines (7) as well as to 6,7,9,13b‐tetrahydro‐9‐oxo‐benzo [a] 1,4‐oxazepino [5,4‐a] isoindoles (6).
Nitration de la Vincamine et de la Vincamone ‐ Hemisynthèse de la Vincinone
Authors: Sarlet P. , Hannart J. 
Published: September 2010

AbstractNitration of vincamine (1) and vincamone (9) in acetic acid introduced only one NO2 group at the C(11) (major compound) vs C(9) (minor compound) position of the eburnane skeleton.Starting from 11‐nitro vincamone (12), vincinone (17) was obtained by suitable transformations of the NO2 group, thus affording a chemical proof of the structure of the 11‐nitro derivatives.
Recherche Documentaires Automatiques Dans le Domaine des Prostaglandines à L'Aide du Système DARC
Authors: Berte M. , De Laet F. 
Published: September 2010

AbstractThe DARC system, created by professor E. DUBOIS, permits the representation of chemical structures by means of linear and biunivocal topologic descriptors (DEL). The system combines the advantages of a topologic code and those of a fragmentory one. The codification and retrieval is made directly on the basis of the structure and requires no knowledge of the system.A pilot project has been started for novelty and inventivity search purposes; to this end a data bank of approximately 15.000 very similar structures has been utilised.
A General Method for the Interpretation of Second Order Properties in Terms of Localised Orbitals
Authors: Alsenoy Christian Van , Geerlings Paul , Figeys Hubert P. 
Published: September 2010

AbstractA general method is presented for the interpretation of second order properties in terms of localised orbitals. The method leads to a set of linear equations which is to be solved but whose dimension rapidly becomes a prohibitive factor for routine work. Three approximation schemes are proposed. The first one uses the maximalisation of intraorbital electronic repulsion integrals, which is the basic idea in localisation procedures; the cither two are based on the well known NDO‐principle.
Structure de la Dichloro‐4,6 Cyano‐5 N‐Méthyl N‐β‐Chloroéthyl Amino‐2 Pyrimidine
Authors: Tinant B. , Germain G. , Declercq J. P. , van Meerssche M. 
Published: September 2010

AbstractThe structure of the title compound has been investigated using X‐ray diffractometer intensities. Crystal data are as follow: triclinic, P1; a = 12.019(4), b = 9.353(4), c = 5.062(1)Å, α = 94.31(2), β = 87.92(2), γ = 99.64(3)°; Z = 2; Dx = 1.57 Mg m−3.
Heterocycles from Acyl Isothiocyanates and Alkyl Azides
Authors: L'abbé Gerrit , Komatsu Mitsuo , Martens Catherina , Toppet Suzanne , Declercq Jean‐Paul , Germain Gabriel , Meerssche Maurice Van 
Published: September 2010

AbstractAlkyl azides react with aroyl isothiocyanates at ca 50° to yield 1,2,4‐dithiazolidines (2) and 1,2,4‐thiadiazoles (4). The latter were isolated as the major products in all cases except that of p‐nitrobenzoyl isothiocyanate. Their structure attribution was based on elemental and spectral analyses, and, in the case of 4d, on an X‐ray diffraction study. Compound 4d exhibits a nearly linear NS…O arrangement with a S…O distance of 2.52 Å, indicating no‐bond resonance.
Synthèse de Thienylthieno [2,3‐b] Thiophènes, Bithieno [2,3‐b] Thiophènes et des Sulfures Correspondants
Authors: Meunier P. 
Published: September 2010

AbstractMost of the compounds containing a thieno[2, 3‐b] thiophen ring connected directly or through a sulfur atom to a thiophen ring, or even to a second thieno [2, 3‐b] thiophen ring, are accessible from a thieno [2, 3‐b] thienyllithium. Derivatives which carry a halogen atom on each cycle in the “ortho” position to the junction can be prepared from a halogenothieno [2, 3‐b] thienyllithium, or by halogenation of the heterocycles. The structure of the compounds was established by NMR analysis.
A New Synthesis of (S) ‐ ( + ) ‐1,5‐Cyclotrimethylene‐3‐Phenyl‐2‐Thiohydantoin
Authors: Poupaert Jacques H. , Lhoëst Georges 
Published: September 2010

Abstract(S)‐(‐)‐1,5‐Cyclotrimethylene‐3‐phenyl‐2‐thiohydantoin is synthesized by thermal cyclodehydration of corresponding phenylthiohydantoic acid. This method yields nearly quantitatively a product of molecular rotation higher than that obtained by acid catalysed cyclisation of the phenylthiohydantoic acid. Spectral data (mainly MS and IR) supporting the structure assignment are presented and the synthetic scope of the method is discussed.
Influence of the dispersion of platinum and effect of poisons on its activity and selectivity for various test reactions
Authors: Barbier J. , Morales A. , Marecot P. , Maurel R. 
Published: September 2010

AbstractA series of Pt/Al2O3, catalysts was prepared, the metal dispersion ranging from 5 to 80% as the metal loading varies. Their activities in respect to the hydrogenation of benzene (I) epimerisation of cis 1‐2 dimethyl cyclohexane (II), hydrogenolysis of cyclopentane (III), exchange of benzene (IV), monoexchange of cyclopentane (V) and multiple exchange of cyclopentane yielding d product (VI) were measured.It is shown that reactions (I) and (II) are structure insensitive. On the other hand, reactions (III), (IV), (V) and (VI) are structure sensitive but reactions (III) and (VI) point out the same sensitivity to the structure when the sensitivities of reactions (IV) and (V) are exactly the same.The effect of adsorption of different compounds has been studied. It was found that many of those poisons are “non selective” i.e. they affect all reactions in the same ratios. In the other hand “selective” poisons display different toxicities for reactions which point out different structure sensitivity.Some possible explanations are discussed but finally the surface presumably displays a variety of catalytic sites and the selective poisoning may be a consequence of non uniform adsorption of the poisons.
Force field study op some hexahalide ions
Authors: Namasivayam R. , Kannan K. 
Published: September 2010

AbstractThe force field study of some hexahalide ions (Mm6−n) is attempted by the method of Redington and Aljibury. The angle parameter has been fixed for all the ions to obtain the symmetrised force constants. Mean amplitudes of vibration and Coriolis coupling constants have also been evaluated. The results are discussed in detail.
Complexes of lanthanide nitrates with 2‐n‐acetylaminopyrimidine
Authors: Rajasekar N. , Soundararajan S. 
Published: September 2010

AbstractNew complexes of lanthanide nitrates with 2‐N‐acetylaminopyrimidine (ApymH) of the composition Ln(ApymH)2 (NO3)3 where Ln = La‐Yb and Y have been synthesised and characterised by conductance, infrared, 13C and 1H NMR (for La3+ and Y3+ complexes only) and electronic spectra. The molar conductance and infrared spectral data show that all nitrate groups are coordinated to the metals. IR and NMR evidence point to the bidentate chelation of the ligand through the pyrimidine nitrogen and oxygen of the acetylamino group. A probable coordination number of ten has been assigned for all the complexes.
The conformation of 1‐formyl‐ and 1‐acetylhexahelicene
Authors: Lindner Hans Jörg , Kitschke Brigitte 
Published: September 2010

AbstractThe structures of 1‐formylhexahelicene (1) and 1‐acetylhexahelicene (2) were determined by X‐ray structure analyses. In the crystalline state, both compounds have conformations with the smaller group of the substituents (H in 1, 0 in 2) directed to the centre of the helicene system. πhyphen;SCF‐ force field calculations predict that these conformations are the most stable ones of the isolated molecule as well.
Propellanes. LIV. Reactions of [4.4.1], [4.3.1] and [4.2.1] Propella‐2,4‐Dienes with 4‐Substituted‐1,2,4‐Triazoline‐3, 5‐Diones
Authors: Ashkenazi P. , Kaftory M. , Ginsburg D. , Grimme W. , Heger K. , Vogel E. 
Published: September 2010

AbstractAs expected, the title dienophile always undergoes Diels‐Alder reactions with the title dienes by attacking anti‐ to the cyclopropane ring.
The polarized luminescence and vibrational optical activity of calycanthine
Authors: Barnett Christopher J. , Drake Alexander F. , Mason Stephen F. 
Published: September 2010

AbstractMeasurements of the circular intensity differential in the fluorescence of calycanthine, and of the linearly‐polarized excitation and emission spectrum, are found to support the exciton analysis of the electronic CD spectrum, upon which the determination of the absolute stereochemical configuration of the molecule is based. The observed vibrational IRCD of the N‐H stretching mode of calycanthine is shown to originate principally from chromophore‐substituent coupling, and not from the degenerate interchromophore coupling particular to chiral dimers. The general chromophore‐substituent coupling mechanism provides a procedure for the determination of absolute configuration from the IRCD associated with a localised characteristic vibrational mode.
Addition of dihalocarbenes to quadricyclane
Authors: Jefford Charles W. , Gehret Jean‐Claude E. , de los Heros Viktor 
Published: September 2010

AbstractQuadricyclane (1) was allowed to react with dichloro and difluorocarbene. Cheletropic reaction occurred in both cases affording cyclopropane and cyclobutane adducts. Dichlorocarbene, being more electrophilic, underwent predominantly 1,2 cheletropic reaction with 1 yielding the cyclobutane adduct. Difluorocarbene gave mostly the exo cyclopropane adduct via 1,4 cheletropic reaction. The results are discussed in terms of the frontier orbitals and compared to the results obtained with norbornadiene.
Cristallisation Hydrothermale de Gels Alumino‐Silicates et Magnesio‐Silicates en Présence D'Hydroxyde De Calcium
Authors: De Vynck Ivan A. 
Published: September 2010

AbstractThe hydrothermal transformations of different compositions belonging to the systems CaO‐Al2O3‐SiO2, X2O‐CaO‐AL2O3‐SiO2 (X = alcali), CaO‐MgO‐SiO2 and CaO‐MgO‐Al2O3‐SiO2 are studied in the temperature range 300 to 650°C.The treatment of some mixtures containing CaO, Al2O3 and SiO2 some times gives pure phases such as margarite, hibschite and anorthite. More currently a mixture of different compounds is obtained, especially at the lower temperatures examinated. Although calcium hydroxide enhances the reactivity of the silicate phase, this action is not as pronounced as for alcali metal hydroxides. In order to obtain well crystallized products the temperature of the treatment must exceed 450 °C.Calcium hydroxide also exhibits a positive action on the crystallization of chrysotile and talc from MgO‐SiO2 mixtures. Diopsite can be obtained as a pure and well crystallized phase at temperatures equal or exceeding 500°C.