bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescence studies of the kinetics of processes in polyelectrolyte and ionomer solutions
Authors: Morawetz Herbert 
Published: September 2010

Abstract(1) A stopped‐flow apparatus with fluorescence detection was employed to follow the expansion of poly(methacrylic acid) (PMA) after a pH‐jump using either a dansyl‐labeled polymer (where emission is quenched by contact of the label with water) or doubly labeled PMA, where the efficiency of nonradiative energy transfer from the donor to the acceptor label decreases with chain expansion. The final approach to conformational equilibrium was found to be unexpectedly slow. (2) The kinetics of the enhancement of the fluorescence of Auramine 0 when it was mixed with the contracted form of PMA was insensitive to the polymer concentration, suggesting that it is due to a conformational transition of the polymer following the adsorption of the dye. (3) Partially ionized polycarboxylic chains carrying a β‐naphthol moiety were used to study the proton transfer from the excited naphthol to ionized carboxyls. The data suggested that the local chain flexibility is independent of the degree of ionization. (4) Solutions of slightly sulfonated polystyrene neutralized with aminomethyl naphthalene and aminomethyl anthracene, respectively, were mixed in the stopped‐flow apparatus and the kinetics of counterion interchange was deduced from the increasing efficiency of nonradiative energy transfer from the naphthalene to the anthracene label. (5) On mixing solutions of methyl methacrylate copolymers with small fractions of 4‐aminostyrene hydrochloride and N,N‐dimethylaminoethyl methacrylate, respectively, the HCl transfer from the aromatic to the aliphatic amine was followed by the increase of fluorescence. Using this model system, it was shown that the rate constant decreases with the length of the chains to which the interacting moieties are attached.
Hétérocyclisations a partir des dérivés des thioamides trifluoropyruviques
Authors: Maliverney C. , Merényi R. , Viehe H. G. 
Published: September 2010

Abstract2‐Aminothioamides as derivatives of trifluoroalanine, and also 2‐tertiary hydroxythioamides as derivatives of trifluorolactic acid have recently been prepared. They have made now the synthesis of new five‐membered heterocycles possible by reaction with phosgeniminium chloride, with phosgene or with methanesulfonyl chloride: thus trifluoromethyl thiazole, ‐thiazolone, ‐benzothiazole and ‐sultones have been obtained.
What Rules the Melting Point of Semi‐Crystalline Polymers?
Authors: Huyskens P. , Groeninckx G. , Vandevyvere P. 
Published: September 2010

AbstractThe melting point Tm of semi‐crystalline polyethylene terephthalate is correlated with the thickness lc/nm of the crystalline lamellae by the unique relation 1/Tm = 1/594.5 + 0.001759/lc. This correlation is independent of the temperature of crystallization, the molecular weight or the annealing. This demonstrates that the melting point is ruled only by the characteristics of the crystalline parts. The molar heat of fusion is 18.4 kJmol−1 per crystallized segment and the corresponding entropy change 30.5 JKmol−1. Both are independent of lc. In the amorphous parts the two segments adjacent to the crystalline lamella have their entropy reduced by 15 J/Kmol as a consequence of the limitations in their possibilities of orientation. However this is a constant effect, independent of the thickness of the amorphous zones, possible entanglements or other characteristics of the amorphous parts.
In‐Situ Composites Based on Thermoplastic and Thermotropic Liquid Crystalline Polymers
Authors: Crevecoeur G. , Groeninckx G. 
Published: September 2010

AbstractThermotropic liquid crystalline polymers (TLCPs) can be used to reinforce thermoplastic polymers in so‐called in‐situ composites. A brief introduction on contemporary TLCPs is given, followed by the basic ideas and principles behind in‐situ composites. The state‐of‐the‐art of in‐situ composites is presented in terms of morphology and mechanical properties. Composite models that describe the mechanical properties of in‐situ composites are discussed. Finally, some rheological parameters determining the processing and morphologies of in‐situ composites are emphasized. At the end of the paper an outlook on possible topics of future interest is given.
Synthesis and Stability of Functionalized Epoxides Topologically Related to β‐Lactam Antibiotics
Authors: Marchand‐Brynaert Jacqueline , Ferroud Didier , Serckx‐Poncin Béatrice , Ghosez Léon 
Published: September 2010

AbstractEpoxides 3‐4 topologically related to penicillins and oxamazins have been designed as potential alkylating inhibitors of bacterial D, D‐peptidases. A series of N‐acylated olefins 17‐19 and 22 have been prepared. It was found that the corresponding epoxides bearing a free carboxyl group were unstable. Neither the olefinic precursors nor the lactones 23 resulting from ring opening of the epoxides 4 exhibited any antibacterial activity.
Dimérisation De Dienes Conjugués A L'Aide De Complexes Du Nickel En Présence De Ligands De Type Aminophosphinite Étude D'Optimisation
Authors: Masotti Henrietta , Peiffer Gilbert , Siv Chhan , Courbis Pierre , Sergent Michelle , Phan Tan Luu Roger 
Published: September 2010

AbstractNew chiral aminophosphinite ligands are readily prepared and their behaviour as homogeneous catalysts was investigated in the linear dimerization of butadiene and isoprene. This latter reaction has been optimised using experimental research methodology, leading to a conversion rate above 50%.
First Derivative of the Ratio Spectra Method for Resolving 3‐Hydroxybenzaldehyde and 4‐Hydroxybenzaldehyde in Binary Mixtures
Authors: Berzas Nevado J. J. , Guiberteau Cabanillas C. , Salinas López F. 
Published: September 2010

AbstractA method for the simultaneous determination of the isomers 3‐hydroxybenzaldehyde and 4‐hydroxybenzaldehyde in binary mixtures is proposed. The method is based on the use of the first derivative of the ratio spectra obtained by dividing the amplitudes, at appropriate wavelengths, of the absorption spectra of the mixtures by a standard of 4‐hydroxybenzaldehyde for determining 3‐hydroxybenzaldehyde and by a standard of 3‐hydroxybenzaldehyde for determining 4‐hydroxybenzaldehyde. The method compares favourably with other spectrophotometric methods.
The Preparation of α‐Hydro‐ω‐Hydroxypoly(Oxyethane‐1,2‐Diyl) Ditosylate (Peg(OTs)2) Revisited
Authors: van Den Berge L. , van Damme S. , Anteunis M. J. O. , Tavernier D. 
Published: September 2010

AbstractAn improved protocol for the preparation of the title compound [PEG(OTs)2] from polyethylene glycol, tosyl chloride, 4‐dimethylaminopyridine (DMAP) and triethylamine is described. PEG(OTs)2 reacts slowly with DMAP to yield, by a nucleophilic displacement of ‐OTs, PEG(DMAP)2+ (OTs−)2 (DMAP+ = 4‐dimethylamino‐pyridinium‐1‐yl). PEG(OTs)2, heated in N,N‐dimethylformamide, is extensively transformed into ‐PEG‐OC(=O2)H.
Une Nouvelle Récyclisation De Cations 1,3‐Hétérocycliques En Cations Benzimidazolium Et Perimidinium
Authors: Védernikova I. V. , Konstantinchenko A. A. , Ryabukhin Yu. I. 
Published: September 2010

AbstractIn this work we have examined the new recyclisation of 1,3‐heterocyclic cations activated towards 1,4‐binucleophyles: o‐phenylenediamines and 1,8‐naphthalenediamines. This reaction leads to the formation of benzimidazolium and perimidinium cations.
One‐Pot Synthesis of 2,2,4‐Trichlorobutanal from Tetrahydrofuran
Authors: De Buyck Laurent , Menke Niclas , Louagie Jan 
Published: September 2010

AbstractTetrahydrofuran was converted to 2,2,4‐trichlorobutanal (1) in 60‐73% overall yield by isomerisation of intermediate 2,3,3‐trichlorotetrahydrofuran (2) in the presence of 4‐6% (w:w) of aluminum trichloride at 100‐140°C for 40‐60 rain. Zinc chloride and titanium tetrachloride were less effective as catalysts, while hydrogen chloride and paratoluenesulfonic acid were ineffective.
Spectroscopic Electronegativities of Halogens are Transferable and Additive Parameters. Examples of Correlations with Thermochemical and Nuclear Magnetic Resonance Spectroscopic Data
Authors: Screttas Constantinos G. , Micha‐Screttas Maria 
Published: September 2010

AbstractSets of enthalpies of formation of a) halogens and interhalogens b) tetrahalomethanes c) haloethenes and d) hexahaloethanes are correlated with the corresponding sums of the spectroscopic electronegativity parameters. Similarly, carbon‐13 NMR shifts of tetrahalomethanes are linearly related to the respective sums of the above electronegativities. The latter correlation allowed the prediction of the C‐13 chemical shifts of 28 tetrahalomethanes, several of which are well outside the range of a low power NMR instrument.
New Cs2CO3 Catalyst for the Wittig‐Horner Synthesis of Acrylates in Interfacial Solid Liquid Conditions
Authors: Sinisterra J. V. , Barrios J. , Mouloungui Z. , Delmas M. , Gaset A. 
Published: September 2010

AbstractCesium carbonate is described as an efficient catalyst for the Wittig‐Horner reaction in interfacial solid‐liquid conditions. This solid is more effective catalyst than potassium carbonate or activated barium hydroxide catalyst (C‐200), under the same experimental conditions. Phenolic aldehydes or aldehydes with N‐H group can only carry to acrylate in the presence of cesium carbonate. These aldehydes are not reactive when potassium carbonate or C‐200 are used as catalysts. The synthetic method is described and the influence of the cesium carbonate structure on the yield is discussed. The mechanism of the reaction is qualitatively described in terms of the nature of adsorbed species and the influence of the solid cell lattice on the yield. The difference in the catalytic activity observed in the solid bases tested is discussed on the bases of an interfacial solid‐liquid mechanism.
Photochromisme des Spiropyranes. Étude de la Colorabilité et de la Photodégradation de Dérivés Non‐Azahétérocycliques
Authors: Gaude Didier , Gautron René , Guglielmetti R. 
Published: September 2010

AbstractStudy of the photodegradation and the “colorability” of non‐azaheterocyclic spiropyrans by repeated flashes showed the influence of different effects involving the heteroatom, the substituent and the concentration. Substituents in 3′, 6′ and 8′ positions of the benzopyran part are very important for stabilization of the colored open form (thermal bleaching kinetic constant), for “colorability” and photodegradation. The primary photochemical process is essentially localized in the benzopyran part but in the photomerocyanine isomer there is interaction between the two moieties. The “colorability” and the photodegradation vary inversely with concentration. All compounds present generally a bad “colorability” but also a sufficient light‐stability at high concentrations. A general scheme for the photocoloration and photodegradation of spiropyrans is also proposed.
Étude par Photolyse à Éclairs Répétés de la Photodégradation et de la Colorabilité de Quelques Spiro[Indoline‐Oxazines]
Authors: Gautron René , Eloy Dominique , Escaffre Pascale , Guglielmetti Robert , Pottier Eliane , Tardieu Pascale 
Published: September 2010

AbstractThe “colorability” and the photodegradation by repeated flashes have been studied for 3 series of photochromic spiro[indoline‐oxazines], A comparison has been established, in the same conditions, with indoline derivatives in benzopyran and naphthopyran reference series. The oxazine compounds present generally a better behaviour to the light but the low photodegradation depends also on the UV region of irradiation, the pane glass (λ > 335 nm) being an interesting filter. The spiro [indoline‐oxazines] have a good balance between photocoloration and photodegradation.
Identification D'isomères du Dodécane Mesures des Indices de Rétention a Plusieurs Températures
Authors: De Laet M. , Tilquin B. 
Published: September 2010

AbstractPure 3‐methylpentane was irradiated in its solid vitreous state at 77 K. The qualitative analysis of the dimeric products was made by mean of capillary chromatography coupled with mass spectrometry. The identification of the dimers, highly branched dodecanes, required the synthesis of compounds whose structure was defined by NMR 13C DEPT; they were characterised by their retention index measured at several temperatures on the capillary SE30 column.
Reductive Cleavage of Cyclic Ketals with ZrCl4‐LiAlH4
Authors: Shaozu Wu , Tianhui Ren , Yulan Zhang 
Published: September 2010

AbstractBoth aliphatic and aromatic cyclic ketals were selectively reduced to the corresponding glycol monoethers in high yield with ZrCl4‐LiAlH4 at 30°C in Et2O for 12 hr.
Synthesis and Crystal Structure Determination of 3,4‐Dimethoxybenzyl 2,3,4‐Trimethoxyphenyl Ketone
Authors: Arriortua M. I. , Via J. , Urtiaga M. K. , Domínguez E. , Igartua A. , Sotomayor N. 
Published: September 2010

AbstractX‐Ray crystallographic investigation of the product obtained by acylation of 1,2,3‐trimethoxybenzene with 3,4‐dimethoxyphenylacetyl chloride is reported. The IR and NMR spectral studies in solution are in agreement with the crystal structure. The structure confirms the distorted tetrahedral arrangements around the methylene group as observed for other deoxybenzoins.
Novel 4,5‐Dihydropyrazolo[3,4‐d]Pyrimidin‐4‐Ones and 3,4‐Dihydropyrazolo[3,4‐d]‐1,2,3‐Triazin‐4‐Ones
Authors: Maquestiau A. , Banneux F. , Vanden Eynde J.‐J. 
Published: September 2010

Abstractβ‐benzylidene 3− and 5‐amino‐1‐methyl‐1H‐pyrazole‐4‐carboxhydrazides 3 and 4 readily react with orthoesters to yield the 4,5‐dihydropyrazolo [3,4‐d] pyrimidin‐4‐ones 5‐8.Syntheses of 3,4‐dihydropyrazolo [3,4‐d]‐1,2,3‐triazin‐4‐ones 9, 10, 13 and 14 were achieved by nitrosation of various 3− and 5‐amino‐1‐methyl‐1H‐pyrazole‐4‐carboxhydrazides.
Reaction of Carbon Monoxide with Iron(II) Thiolates. Preparation and Structure of fac‐[Na(15‐Crown‐5)][Fe(CO)3(SPh)3] and fac‐[K(18‐Crown‐6)][Fe(CO)3(SPh)3]
Authors: Nagy‐Magos Zsuzsa , Markó László , Szakács‐Schmidt Anikó , Gervasio Giuliana , Belluso Elena , Kettle Sidney F. 
Published: September 2010

AbstractSolutions of Fe(II) and thiolates (RS‐: Fe2+ > 2; R = alkyl, phenyl) absorb carbon monoxide and ‐ depending on the reaction conditions ‐ several different anionic iron carbonyl derivatives are formed. Two of these complexes, fac‐[Na(15‐crown‐5)][Fe(CO)3(SPh)3] (1) and fac‐[K(18‐crown‐6)][Fe(CO)3(SPh)3] (2) were isolated and their crystal structures determined. (1) Crystallizes in the triclinic space group P1 with a = 11.915(3)Å, b = 12.391(3)Å, c = 14.337(3)Å, α = 65.77(5), β = 116.28(5)°, γ = 105.87(5)°, V = 1720(1)Å3, Z = 2, dcalcd = 1.30 gcm−3; (2) crystallizes in the cubic space group Pa3, with a = 19.609(4)Å, V = 7540(3)Å3, Z = 8, dcalcd = 1.4 gcm−3. Final agreement factors were R = 0.092, Rw = 0.102 (3919 reflections with F>7σ(F)) for (1); and R = 0.069, Rw = 0.050 (1125 reflections with F>4σ(F)) for (2). Both [Fe(CO)3(SPh)3]− anions of 1 and 2 have the same octahedral ligand arrangement with the carbonyl ligands cis to each other and trans with respect to the thiolato ligands. In complex 2 the K+ lies on the crystallographic threefold axis and is therefore exactly equidistant (3.475(2)Å) from the three sulphur atoms; on the contrary in complex 1 in the Na+ is nearer to two of the three sulphur atoms (3.083(6)Å and 3.334(6)Å for the two different Na…S distances). The infrared spectra of the compounds were recorded in a variety of solvents and in the solid state. The Raman of crystalline 2 was also recorded. The failure of the vibrational spectra of crystalline 2 to follow either molecular point group or factor group predictions is explained in terms of an effective vibrational unit ‐ and so, effective factor group ‐ similar to that implicit in a factor group analysis of 1.
Synthesis and Flash‐pyrolysis of Organotin ‐Substituted Carbamates and Oxalates
Authors: Ratier Max , Khatmi Djamel , Duboudin Jean‐Georges 
Published: September 2010

AbstractOrganotin ‐substituted alcohols react readily with aryl(alkyl) isocyanates and oxalyl chloride to give the corresponding organotin ‐ substituted carbamates and oxalates. Under flash pyrolytic conditions, these esters decompose into vinyltin derivatives.
C‐Versus N‐Substitution at 1,5‐Diarylformazans with Cyclopropenylium Electrophiles
Authors: Weiss Robert , Lowack Rainer H. 
Published: September 2010

AbstractSynthesis and properties of the first formazan substituted with a cyclopropenylio group in the 5− or 3‐position are described. The latter isomer can adopt syn,s‐cis or anti,s‐trans configurations and can be oxidized to the corresponding cyclopropenyliotetrazolium salt.
Influence of the Hydroxyl Groups on the Basicity of Alkanolamines in Water and in Ethanol‐Water Mixtures
Authors: Stevens G. , Chen S. , Huyskens P. , De Jaegere S. 
Published: September 2010

AbstractThe presence of the OH groups in alkanolamines weakens the basicity of the lone pair of electrons as expressed by the pKaof the compounds in water or in water‐ethanol mixtures. This can be ascribed to a residual electronic delocalization from the N atom to the O atom crossing the CH2groups. The effect that is of the order of −1 pKaunit for two intermediary CH2groups, gradually decreases when this number increases and becomes completely negligible beyond four groups. When two or three OH groups are present in the amino compound the effects are additive as long as the groups are located at different sides of the nitrogen atom (di‐ or trialkanolamines). When two OH groups are situated at the same side of the N atom as in 1‐amino‐2, 3‐diols, the contribution of the end group in the delocalization becomes negligible. The effects remain quantitatively the same in the less polar ethanol‐water mixture.
Synthesis of Methyl 3‐(N‐Bromoacetylamino)‐2‐Naphthoate
Authors: Párkányi Cyril , Sappok‐Stang Annette 
Published: September 2010

AbstractMethyl 3‐(N‐bromoacetylamino)‐2‐naphthoate (3) was obtained from 3‐amino‐2‐naphthoic acid (1) as the starting material, with methyl 3‐amino‐2‐naphthoate (2) as the intermediate.
Synthesis and Evaluation of the Hydrolytical Stability of Ethyl 2‐(α‐Amino acid)Glycolates and Ethyl 2‐(α‐Amino Acid)Lactates
Authors: Crommen Jan H. L. , Schacht Etienne H. 
Published: September 2010

AbstractFour depsipeptides, ethyl 2‐(O‐glycyl)glycolate (1), ethyl 2‐(O‐glycyl)lactate (2), ethyl 2‐(O‐alanyl)glycolate (3) and ethyl 2‐(O‐alanyl)lactate (4) have been synthesized under mild reaction conditions and in relatively high yield. The hydrolytic stability of these esters in methanol, in presence of water and an organic base has been studied by means of proton NMR‐spectroscopy. It was found that, under these conditions, these compounds hydrolyse slowly under and that no intermolecular condensation reactions occur. It was further demonstrated that the glycolate or lactate ester bond in these compounds hydrolyses much faster when compared to the ethyl ester. The potential use of these derivatives in synthesis and application of biodegradable polymers is discussed.
Accuracy in Single‐Crystal X‐Ray Diffractometry: Influence of Atmospheric Pressure, Scan Mode and Crystal Settlement on Intensity Profiles
Authors: Lenstra A. T. H. , Verbruggen M. , Bracke B. , van Dijk B. , Vanhulle C. , Vanhouteghem F. 
Published: September 2010

AbstractSimple statistical analysis of time series of intensity control reflections leads to: (i) quantitative description of the influence of atmospheric pressure on X‐ray intensity measurements, which supplies arguments not to optimize an experimental instability factor p in the least‐squares analysis, as is sometimes practised. (ii) the detection of scan mode ω vs ω/2θ) as a factor in the reproducibility of reflection profiles. The distribution of profile gravity centers revealed a random alignment error due to tolerance in diffractometer gear‐wheels and a systematic one due to friction in the same parts during movements, (iii) a sensitive test to detect small movements (settlements) of the crystal during the data collection. It allows to omit dedicated orientation control measurements, using instead the profiles of intensity control reflections to trigger a re‐orientation procedure, (iv) the recognition of severe limitations to fit observed profiles onto “learned” ones and of limitations in the precision of cell dimension determinations.
NO3−‐ CO32‐Anion Exchange During Washing of Ni‐Al Hydroxycompounds
Authors: Evana Eugenia , Marchidan Rodica , Mănăila Rodica 
Published: September 2010

AbstractAn anion exchange of NO3−with CO32−anions was evidenced by X‐ray diffraction, chemical analysis and IR spectroscopy, during washing of Ni‐Al hydroxycompounds (HCPs) precipitated at pH values less than 7. The anionic composition of the resulting HCP is determined by the pH value of the washing water. In the ‘increasing pH’ method of HCP preparation, the precipitation process is shown to be accompanied by a process of anion exchange. The degree of disorder of the interlayer and in the brucite‐like layer stacking is discussed in terms of the IR spectroscopy data and XRD line broadening.
Modulation De La Regiochimie De La Reaction Du Fluoroborate De 2‐Benzoyl‐1,2‐Dihydroisoquinaldonitrile Sur L'Indene
Authors: Monnier Karin , Schmitt Gérard , Mercier Marie‐France , Rodier Noël , Theobald François 
Published: September 2010

AbstractThe reaction of the 2‐benzoyl‐1,2‐dihydroisoquinaldonitrile fluoroborate salt with indene leads to a single indeno[1,2‐c]pyrrole derivative. But nmr data did not prove the regiochemistry of the reaction and a chemical demonstration has been carried out. It allows to obtain the regioisomeric indeno[1,2‐c]pyrrole derivative. Moreover the last structure was also established by a radiocristallographic study.
Non‐Invasive in Vivo Determination of the Absolute ATP Concentration in the Rat Liver by 31P NMR Spectroscopy
Authors: Miot Françoise , van Cauteren Marc , Rooze A. Katelijne , Geerts Albert , Osteaux Michel , Willem Rudolph 
Published: September 2010

AbstractThe concentration of ATP in the rat liver was determined in vivo by means of surface coil 31P NMR spectroscopy. The double standard method was used in order to achieve absolute quantification of ATP through its 31P β‐resonance. Contamination of the 31P NMR liver spectra by contributions from abdominal muscle tissue was minimized by applying the FROGS presaturation sequence. Difficulties inherent to the B1 inhomogeneity of surface coils were overcome by the use of adiabatic half passage sech/tanh RF pulses. While in the normal rat liver the mean ATP concentration was 3.39 ± 0.31 mM, fibrotic rat livers exhibited a significantly lower average ATP concentration of 2.29 ± 0.31 mM.
Syntheses De Carbonates Et Carbamates Benzyliques Et Allyliques
Authors: Kryczka Boguslaw 
Published: September 2010

AbstractDifferent methods for the preparation of carbonates and carbamates derived from 1‐phenylethyl, 2‐cyclohexenyl and 1‐methyl‐2‐propenyl are described. These compounds have been synthesized by the reactions of alcohols, phenols or amines with chloroformiates, imidazolocarbonates or corresponding mixed p‐nitrophenylcarbonates.It is shown that these reactions can also be used for the introduction of 1‐phenylethyloxycarbonyl ‐ (I), 2‐cyclohexenyloxycarbonyl ‐ (II) and 1‐methyl‐2‐propenyloxycarbonyl ‐ (III) groups into alcohols, phenols and amines for the protection of hydroxyls and amino‐groups.