bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conductance Study of Tetraphenylboride Salts of Alkaline Earth Metals in Tetrahydrofuran
Authors: De Groof B. , De Smedt C. , Vankerckhoven H. , van Beylen M. 
Published: September 2010

AbstractThe conductance behavior of the tetraphenylboride salts of the alkaline earth metals (MB2) has been studied in the temperature range from + 20°C to ‐70°C in tetrahydrofuran (THF). A detailed knowledge of their dissociation into free MB−+ and B− ions is desirable in order to better understand their influence in anionic polymerizations of e.g. styrene with alkaline earth metals as counterions. The thermodynamic parameters as well as the λ+0‐values for the respective salts are taken to indicate a double solvent separated ion pair structure for the calcium and strontium salt represented as B−//M2+//B− and a mixed ion pair structure for BaB2 represented as B−, Ba2+//B−. For MgB2 an ion pair structure B−, Mg2+//B− is proposed at higher temperature changing to B−//Mg2+//B− at lower temperatures.
The Mechanism of Action of Hindered Amine Stabilizers. Production of Nitroxy Radicals and Inhibition of the Photo‐Oxidation in Different Polymers
Authors: Geuskens G. , Kanda M. N. , Nedelkos G. 
Published: September 2010

AbstractOxidation of bis[2,2,6,6‐tetramethyl‐4‐piperidinyl] sebacate (HALS) to itroxy radicals has been monitored by ESR spectroscopy in three polymers: an ethylene‐propylene random copolymer (EPM), a styrene‐butadiene‐styrene block copolymer (SBS) and the same block copolymer previously hydroperoxidized by reaction with singlet oxygen. Nitroxy radicals are produced in all three polymers on irradiation in the presence of oxygen and, in the last one also in the dark, at room temperature. The mechanism of the reaction is discussed: it involves direct interaction of a peroxy radical with the piperidine nitrogen. The role of clustered hydroperoxides as a source of peroxy radicals is emphasized.Inhibition of the photo‐oxidation of all three polymers by HALS has been studied by oxygen absorption measurements and by infra‐red spectroscopy in the carbonyl region. The results indicate that HALS not only inhibits the propagation of the photo‐oxidation but also catalyses a new type of termination that, in some polymers, delays the production of ketones. It is suggested that the practical efficiency of HALS in keeping the mechanical properties of polyolefins exposed to sunlight is mainly due to that last effect.
Radiation Chemistry of N‐Hexane Aqueous Solutions as Studied by Chromatographic Analysis of Final Products
Authors: De Doncker J. , Tilquin B. 
Published: September 2010

AbstractRadiolysis of dilute oxygen‐free hexane aqueous solutions give dodecanes isomers analyzed by capillary gas chromatography. The relative yields for radicals which react by radical‐radical recombination reactions are 39 %, 32 % and 29 % for primary hexyl radical, secondary‐2 hexyl radical and secondary‐3 hexyl radical respectively. This distribution is changed with the N2O saturation before the radiolysis to 22 % 42 % and 37 %. If the first distribution is statistic, the increase of OH available to attack the solute gives the distribution existing in pure alkane radiolysis.
Synthesis and Characterization of Cinnamaldehyde Ferrocene‐Carbonylhydrazone and its Complexes with Lanthanide
Authors: Yong‐xiang Ma , Guo‐sheng Huang , Pei‐song Jin , Xiao‐jun Han 
Published: September 2010

AbstractA new ligand, cinnamaldehyde ferrocenecarbonylhydrazone, FcCONH‐N = CHCH = CHPh (Cafch) (Fc = η5‐C5H5FeC5H4 and its chelates with lanthanide, Ln(Cafch)3Cl3·O‐4H2O(Ln = Y and lanthanide) have been prepared by the reaction of the Cafch with LnCl3 and characterized by elemental analysis, IR,1H n.m.r., electrolytic conductivities, TG and DSC measurements. In these chelates the ligand coordinates to lanthanide ion in the keto form and the coordination numbers of the central metal ions are probably equal to eight.
Isotope Labelling Studies of Some Aromatic N‐Oxides ‐ Part IV. A Full Vibrational Assignment of the Infrared Spectra (4000‐50 CM−1) of Quinoline N‐Oxide Dihydrate and its Fully Deuterated Analogue
Authors: Thornton David A. , Watkins Gareth M. 
Published: September 2010

AbstractFull infrared vibrational assignments (4000 to 50 cm−1) of quinoline N‐oxide and its fully deuterated analogue have been made. Coupling within the molecule is examined employing the νD/νH ratio and by comparison with similar molecules.
Recherches En Série Benzodiazepine‐1,5: Synthèses Des Ditriazolo‐[4,3‐a; 3,4‐d]‐Benzodiazepines‐1,5
Authors: Essassi E. M. , Lamkadem A. , Zniber R. 
Published: September 2010

AbstractThe action of several o‐phenylenediamines on malonic acide was studied. Six, new dítriazolo‐[4,3‐a; 3,4‐d]‐1,5‐ benzodiazepines were prepared from 1,5‐benzodiazepin 2,4‐diones‐Their structures are supported by 1H nmr, ir, mass spectrometry and elemental analysis
Benzylation of 1‐Benzylidene‐3‐Pyrazolidinium Oxides
Authors: Dowling† James E. , Anselme J.‐P. 
Published: September 2010

AbstractThe benzylation of 1‐benzylidene‐5‐phenyl‐3‐pyrazolidinium oxide (2a) gives five products including the “head to head” dimer of 2 (7) and the ring‐opened 1‐benzyl‐1‐cinnamoylbenzalhydrazone (4a). Similar behavior was also observed with ylides bearing various substituents at the 4 and 5 positions.
Reductive Coupling of Benzoic Acid Halides and Esters Using Low‐Valent Titanium
Authors: Dang Y. , Geise H. J. 
Published: September 2010

AbstractThe reductive coupling of (substituted) benzoic acid chlorides and esters is achieved using low‐valent titanium, generated from TiCl3 and LiAlH4. Both acid chlorides and esters seem to follow the same two reaction pathways: one path via tolanes to stilbenes, the other via benzils to complex mixtures of products arising from reduction and further coupling reactions. Although the exact product balance depends upon the reaction conditions the major product is (substituted) cis‐stilbene.
Synthesis and Biological Activities of Bradykinin Analogues with Ψ(E,CH=CH) and Ψ(CH2‐NH) Isosteric Peptide Bond Replacements
Authors: Scarso A. , Degelaen J. , Viville R. , De Cock E. , van Marsenille M. , van Der Auwera L. , Tourwé D. , van Binst G. 
Published: September 2010

AbstractThe synthesis of bradykinin analogues is described in which the Gly4‐Phe5, Phe5‐Ser6 or the Pro7‐Phe8 peptide bond has been replaced by a trans carbon‐carbon double bond or by a “reduced” peptide bond. Some of the analogues display high potency and prolonged activity in the rat blood pressure test, indicating increased metabolic stability. A clear selectivity is obtained towards the myotropic effect in the guinea pig ileum.
Spectres de Masse FAB en Mode Positif de Cations Hétérocycliques Doublement Charges Apparentes au Dibenzo[a,e]Cyclooctane
Authors: Aubagnac Jean‐Louis , Claramunt Rosa‐Maria , Lavandera José‐Luis , Elguero José 
Published: September 2010

AbstractFAB mass spectra in positive mode of doubly charged heterocyclic cations allow identification of such structures. Furthermore, two characteristics of these spectra (low abundance of the doubly charged cations and the reduction phenomenon) are in agreement with previous results.
Synthèse et Identification des 4‐OXO‐1,4‐Dihydropyrimidines en vue des Applications Pharmacologiques
Authors: Védernikova I. V. , Ryabukhin Yu. I. , Haitin M. I. , Simkina Yu. N. 
Published: September 2010

AbstractThere is described synthesis of 2,6‐dimethyl‐5‐phenyl‐4‐oxo‐1,4‐dihydropyrimidines and their perchlorates with phenolic or acetoxyphenolic substituent in the 1st position.All these compounds possess activities as tranquilizers and antidepressive and neuroleptic geants.
Novel Platinum(II)‐Diaminobiotin Complexes. Their Synthesis and Characterisation
Authors: Noels A. F. , Nihant N. , Hubert A. J. 
Published: September 2010

AbstractThe diaminobiotin ligand 1 (cis‐3, 4‐diamino‐2‐tetrahydrothiophene valeric acid) was reacted with potassium chloroplatinate and with diaquodiammine platinum(II) cation 3 to yield new platinum complexes which were coordinated in a bidentate fashion through the diamine function of the ligand and have [PtN2Cl2] and [PtN4] geometries respectively.
Nouveaux Décontaminants. Action des Péracides à Groupe Ester sur Quelques Toxiques Insecticides ou de Guerre
Authors: Lion C. , Hedayatullah M. , Bauer P. , Boukou‐Poba J. P. , Charvy C. , Delmas G. , Magnaud G. , Fosset L. , Despagne B. , Sentenac‐Roumanou H. 
Published: September 2010

AbstractA new peroxyacid‐ester series has been obtained and used in the destruction of toxic agents. These structures oROCOC6H4CO3H and ROCO(CH2)nCO3H are more stable than the unsubstituted compounds. The reaction with paraoxon (0,0‐diethyl 0‐paranitrophenylphosphate) and HD (2,2′‐dichlorodiethylsulfide) goes to completion in a very short time. The influence of the R group and the length of the chain (n = 2……12) has been studied. The addition of some long chain tetraalkyl‐ammonium salts enhances the rate of the reaction by micellar catalysis.
An Analysis of Substituent Effects on the Proton and Carbon‐13 Chemical Shifts of 9‐Chloro and 9‐Amino Acridines
Authors: Faure Robert , Galzy Jean‐Pierre , Barbe Jacques , Boukir Abdel Lhatif , Vincent Emile‐Jean , Boyer Gérard , Elguero José 
Published: September 2010

AbstractThe 1H chemical shifts, 1H‐1H coupling constants, 13C chemical shifts, and some 1H‐13C and 13C‐19F coupling constants have been determined for seven 3‐substituted‐9‐chloroacridines and for the corresponding 3‐substituted‐9‐aminoacridines. The effects produced by the substituent in position 3 on the 1H and 13C chemical shifts are discussed using two empirical models, those of Smith and Proulx (F, R, Q*) and Reynolds (σF, σR0, I, O, M).
Unexpected Internal Peptide Butoxycarbonylation of a Linear N‐Me Amide Peptide Derived from Virginiamycin S and Resulting Failure for a Carboxy‐Terminal Sequencing. Preparation of the Tetrapeptide Synthon Thr‐D‐Abu‐Pro‐MePhe‐OBzl
Authors: Moerman Marc C. , Anteunis Marc J.O. 
Published: September 2010

AbstractNext to the preferential butoxycarbonylation of the picolinic hydroxyl group in Virginiamycin S1 (1a) and of VS‐fragments derived therefrom, a second Boc‐group is invariably and specifically implanted at the proximate amide bond preceding Thr (residue 1 in 1a). This exclusive predisposition for the introduction of a second Boc‐group has prevented the accomplishment of a programmed reaction sequence (SCHEME I) that should have led to the preparation of a VS congener, lacking the N‐methyl at position 1 (des‐4MeVS; 1c). On the other hand this predestined “Boc‐ation” at Thr‐NH can be exploited for the removal of the picolinic residue. This possibility has been tested in the succesful five step preparation of a tetrapeptide ester Thr‐D‐Abu‐Pro‐D, L‐MePhe‐OBzl (SCHEME II) starting from natural VS1.
Synthesis of a New Series of Enkaphalin Related Galactosyl Conjugates
Authors: Vansteenkiste Stefan , Schacht Etienne , Haro Isabel , Reig Francesca , Parente Antonio , Garcia‐Anton Jose Maria 
Published: September 2010

Abstract(D‐Met2,Pro5)‐enkephalin‐N‐(β‐D‐galactopyranosyl)amide, a glycopeptide containing a galactose residue at the C‐terminal position of the μ‐selective enkaphalin analogue (D‐Met2,Pro5)‐enkaphalinamide, has been synthesized by the liquid phase procedure according to different strategies. Such analogue exhibited a great antinociceptive potency after intracerebroventricular injection in the “in vivo” tail immersion test when compared to the parent compound and the corresponding glucose derivative. Therefore, we suggest that the opioid receptors mediating analgesia, interact more efficiently with galactosyl rather than glucosyl residues. To confirm this hypothesis, we have synthesized a series of galactosyl conjugated (D‐Met2,Pro5)‐enkaphalins, containing up to three galactose residues linked to the oligopeptide backbone throughout a hydrophobic carbon c‐6 spacer.
A Scanning Tunneling Microscopial (STM) Study of (NH4)2[Mo3S13] · H2O and its Thermal Decomposition Product MoS2
Authors: Diemann E. , Branding A. , Müller A. 
Published: September 2010

AbstractThe LDOS of films of (NH4)2[Mos3S13] · H2O on carbon supports have been studied with positive and negative bias voltage in the scanning tunneling electron microscope. The obtained pictures can be assigned to LUMO and HOMO states formed by the cluster anions, respectively. An important result is that the Mo3 planes are always found perpendicular to the support. This orientation is essentially retained when the film of the cluster compound is thermally decomposed to MoS2.
Etude Des Reactions De Coupure Des Liaisons O‐Si(CH3)3 Dans Des Polystyrenes Silicies En Presence De Sels De Triphenylsulfonium Avec Ou Sans Perylene Sous Irradiation UV Et Visible Et En Couche Mince
Authors: Madit N. , Giral L. , Montginoul C. , Sagnes R. , Schué F. , Rosilio C. , Guibert J. C. 
Published: September 2010

AbstractThis paper describes a positive resist formulation containing silylated polystyrene polymer, made photosensitive at wavelengths from 220 to 310 nm by means of an onium salt sensitizer ((C6H5)3SMXn) and at wavelengths from 360 to 450 nm by means of an onium salt and a dye photosensitizer (perylene). In the present study, we report the desilylation of acid‐sensitive polymers as poly (4‐trimethylsiloxystyrene) or poly [p‐trimethylsiloxystyrene‐co‐p‐(tert‐butoxycarbonyl) oxystyrene]. The formed Brönsted acid which induces the cleavage of silicon ‐ containing side groups is HMXn. The transformation reaction is followed by IR spectroscopy before and after exposure. This resist system is resistant to etching in an oxygen plasma.
Ring Transformations of Pyrazolones Via Azo‐Olefins
Authors: Schmitz Ernst , Lutze Gerhard , Kirschke Klaus , Hübner Petra 
Published: September 2010

AbstractInstead of substitution, 4‐halo‐pyrazolones undergo ring opening to azo‐olefins (2, 12, 16) on reaction with nucleophiles. Attempted Hofmann degradation of N‐Haloamides 4 has to compete with either ring closure, involving NHCl‐shift to 7, or formation of mesoionic compounds 10, whose pyrazolone ring shows a different pattern of nitrogen insertion. Substitution of cyclic amines for chlorine in azo‐olefin 12 is followed by rearrangement to the bicycle 15. Access to 1,2,3‐thiadiazolium salts (18, 22) is possible by electrophilic attack of sulfur reagents to azo‐olefins.
Susceptibilite Electrique Haute‐Frequence De Jonctions Silicium‐Electrolyte
Authors: Ammari M. , Bohnké C. , Bohnké Mme O. , Gire A. , Lomaglio Mme G. , Théobald J.‐G. 
Published: September 2010

AbstractThe electrical susceptibility of the Silicon‐electrolyte interface has been studied when the electrical irradiation field is parallel to the junction. In the High Frequency (H.F.) range, the absorption exhibits one maximum depending on the voltage applied between the semi‐conductor and the electrolyte. This drastic variation, specially the maximum, is at our opinion, due to the minority carriers. It is modified by irradiation. In the microwave range, the maximum of absorption is rather difficult to observe probably because electrochemical reactions occur. The variation of dispersion is negative, we explain that by considering the high frequency local field.
The Use of Thermal Analysis for the Study of the Calcinationprocess of Oxalateprecursors for the Synthesis of High Tc Superconductors
Authors: Vos A. , Mullens J. , Carleer R. , Yperman J. , Vanhees J. , van Poucke L. C. 
Published: September 2010

AbstractThe decomposition of the oxalateprecursors Y2(C2O4)3.4BaC2O4. (6 + n)CuC2O4. xH2O for the synthesis of high Tc superconductors and the individual Y‐, Ba‐, Cu‐oxalate components is investigated by DTA and by TGA coupled with FTIR.
Novel Syntheses of Heterocycles with N‐(1‐Haloalkyl)Azinium Halides Part 1. Preparation of Imidazolidines
Authors: Vanden Eynde J.‐J. , Mayence A. , Maquestiau A. , Anders E. 
Published: September 2010

AbstractN‐(1‐Chloroalkyl)pyridinium chlorides, prepared from thionyl chloride, pyridine, and an aldehyde, readily react with N,N′‐disubstituted 1,2‐ethanediamine to yield imidazolidines under mild and neutral conditions.
Nouveaux Decontaminants. Destruction De Toxiques Organophosphores Ou Soufres Par Des Peracides Mono‐, Bi‐ Et Tricycliques Satures
Authors: Lion C. , Hedayatullah M. , Bauer P. , Boukou‐Poba J. P. , Charvy C. , Delmas G. , Magnaud G. , Fosset L. , Despagne B. , Desgranges M. , Sentenac‐Roumanou H. 
Published: September 2010

AbstractNew peroxycarboxyclic and peroxyacetic acids have been tested for the destruction of some organophosphorus compounds and mustards. The peroxyacids used have monocyclic, bicyclic or tricyclic structures. These are very reactive against paraoxon or HD and the addition of certain surfactants enhances the reaction rate. Very short half‐live times are obtained with these compounds.
The Oxidative Degradation of Polystyrene Studied by the Coupling of Thermogravimetry with Other Techniques
Authors: Mullens J. , Carleer R. , Reggers G. , Ruysen M. , Yperman J. , van Poucke L. C. 
Published: September 2010

AbstractA description is given for the combination of techniques for the study of the oxidative degradation of polystyrene samples with different additives. Thermogravimetry is used for the determination of the degradation profile (weight loss versus temperature). The evolved gases are investigated on‐line by Fourier transform infra‐red spectroscopy. Simultaneously, evolved gases are also collected by an adsorbent and, after the thermal experiment, desorbed to release the volatile products for identification using gaschromatography‐mass spectrometry. The combination of the three techniques offers the unambiguous identification of the gaseous decomposition products as a function of the temperature. The identified products are CO2, H2O, benzene, toluene, xylene and styrene for a first sample; CO2, H2O, toluene, styrene, benzaldehyde and methylstyrene for a sample of a second polystyrene with other additives.
Complexes of the Type R'OOC‐CHR‐CH2SnCl3.OPPh3 Readily Undergo Transesterifications into R”OOC‐CHR‐CH2SnCl3.OPPh3 When Reacted with R”OH
Authors: Fu Fangxin , Li Zhongfang , Tian Laijin , Pan Huade , Kayser François , Willem Rudolph , Gielen Marcel 
Published: September 2010

AbstractComplexes of 2‐alkoxycarbonylethyltin and 2‐alkoxycarbonyl‐2‐methylethyltin trichlorides, R'O‐CO‐CHR‐CH2SnCl3.OPPh3, readily undergo transesterification reactions into the corresponding alkoxycarbonyl analogs R"OOC‐CHR‐CH2SnCl3.OPPh3 when reacted with R"OH.
High Yield Preparation of 2,3,3‐Trichlorinated Tetrahydropyran with an Excess of Refluxing Sulfuryl Chloride in the Dark
Authors: De Buyck Laurent 
Published: September 2010

AbstractThe chlorination of tetrahydropyran with an excess of refluxing sulfuryl chloride in the dark provided 2,3,3‐trichlorotetrahydropyran in 94% isolated yield, showing evidence for a very selective non‐homolytic mechanism, probably involving hydride abstraction as the first step.
Heteroaromatic Cations as Key Intermediates for the Synthesis of Functionalized Dihydro‐Heteroaromatic Compounds
Authors: Akiba Kin‐Ya 
Published: September 2010

AbstractN‐Ethoxycarbonylpyridinium chlorideAwas generated in solution (CH2Cl2or CH3CN) from pyridine and ethyl chloroformate and reacted to tri‐i‐propyl phosphite, RCu·BF3, and silyl enol ethers at 4‐position exclusively to afford 1,4‐dihydropyridine derivatives containing the corresponding phosphonyl (2), R (6), and 2‐oxoalkyl (11) groups in high yields. These were oxidized to the corresponding 4‐substituted pyridines by oxygen. Methyl nicotinate was also quaternized by ethyl chloroformate to generate the nicotinium saltDin situand silyl enol ethers and RCu·BF3added at 4‐position exclusively to give 1,4‐dihydronicotinic esters12, 13in high yields.N‐Methoxy‐carbonylquinolinium chlorideEwas generatedin situand reacted to silyl enol ethers to give a mixture of 2‐ and 4‐adducts. The major adducts15, 1,2‐dihydroquinolines having 2‐oxoalkyl group at 2‐position, were easily separated by flash column chromatography. Trialkyl phosphite reacted toEat 2‐position exclusively to give the corresponding 1,2‐dihydroquinoline‐2‐phosphonate16, which was alkylated at 4‐position exclusively after deprotonation byn‐butyllithium.N‐Ethoxycarbonyl‐isoquinolinium chlorideGwas also generatedin situand reacted to silyl enol ethers at 1‐position exclusively to afford the corresponding 1,2‐dihydroisoquinolines20. 20was used as a precursor for stereoselective cyclization to benzo[a]qionolizine derivatives.Chromone and coumarin reacted neat witht‐BuMe2SiOTf by heating and 4‐ (I) and 2‐(K)‐siloxybenzopyrylium salts were prepared. Both salts reacted with conjugated 2‐siloxydienes and afforded [4+2] type cycloadducts32and37in one‐pot process. The stereochemistry of annulation was cis for all the cycloadducts and the structure of the cycloadducts is discussed in detail based on1H NMR.
From Phosphaalkynes to Phosphacubanes — Adventures in Organophosphorus Chemistry[1]
Authors: Regitz Manfred 
Published: September 2010

AbstractPhosphaalkynes (4) — readily accessible from carboxylic acid chlorides and tris(trimethylsilyl)phosphane — serve as starting materials for the synthesis of phosphirenes (13, 18, 41, 45). The significance of the 1‐chloro‐2‐phosphirene (18) for the generation of phosphirenylium cations (A⟷B or C) as well as its ring enlargement reaction to 1,2‐dihydro‐1,2‐phosphasilete (28) and its ring cleavage reaction to 1,2,3‐butatrienes (48) and vinylallenes (51) are illustrated. The non‐selective thermal cyclotetramerization of 4 to give, among others, the tetraphosphacubane 56 is compared with a preparative, two‐step procedure starting from the tricyclic zirconium complex 60; the latter process provides higher yields of 56. The phosphorus atoms in the pentacyclic system can be functionalized by a wide range (66–73). In the presence of Lewis acids such as aluminium trichloride, phosphaalkynes (4) undergo spirocyclotrimerization to furnish betaines of the type 77.
Action Des Amines Et Des Hydrazines Sur Les Imidates Issus Du Methyl 3‐Amino‐2‐Thiophene Carboxylate. Nouvelle Voie D'Acces Aux [3,2‐d]4(3H)Thienopyrimidinones
Authors: Hajjem B. , Ben Khoud M. L. , Baccar B. 
Published: September 2010

AbstractMethyl 3‐amino‐2‐thiophene carboxylate reacts with orthoesters to produce N‐(2‐carbomethoxy thienyl) imidates 1. Treatment of these imidates with primary amines, hydrazine, methylhydrazine and phenylhydrazine yields only [3,2‐d]4(3H)thieno‐ pyrimidinones 2 and not isomeric 1,3,4‐thienotriazepin‐5‐ones. The type of products obtained gave information relevant to the elucidation of the mechanism of cyclization and the relative activities of the ester and imidate groups.
Preconcentration and Determination of Traces of Strontium in Natural Waters by Ion‐Exchange and Flame Atomic Absorption Spectrometry
Authors: Yebra‐Biurrun M. C. , Bermejo‐Barrera A. , Bermejo‐Barrera P. 
Published: September 2010

AbstractA flame atomic‐absorption spectrophotometric method for determining strontium in natural waters is described. The use of ethylenediamine tetraacetic acid (EDTA) to suppress interferences was studied, and ion‐exchange with Amberlite IR‐120 (H+) to concentrate the metal was used; strontium being eluted with 3% EDTA.The precision and reproducibility of the method were also investigated, and optimum results were obtained. Strontium concentrations for samples analyzed were between 4 and 147 μg/l. The detection limit was 1.6 μg/l, and the sensitivity was 3.2 μg/l for strontium.