bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of P:V Ratio on the Reducibility and Oxidizability of Vanadium Phosphorus Oxide Catalysts
Authors: Hodnett B. K. , Delmon B. 
Published: September 2010

AbstractPreliminary results on reducibility and oxidizability of vanadium phosphorus oxide catalysts with differing P:V ratios are reported. Small amounts of phosphorus in excess of the stoichiometric amount strongly inhibit oxidation of the catalyst during calcination. No clear correlation seems to exist between the kinetics of reoxidation and the initial reactivity of the catalysts towards hydrogen.
Synthesis of alkylindoles in gas phase on an aluminium orthophosphate
Authors: Esteban S. , Marinas J. M. , Martinez‐Alcazar M. P. , Martinez M. , Agarrabeitia A. R. 
Published: September 2010

AbstractThe synthesis of alkylindoles in the gas phase over an aluminium orthophosphate Kearby type catalyst has been studied. As reactants different carbonyl compounds and phenylhydrazine or aniline have been employed. The conditions of temperature and molar ratio of carbonyl compound/nitrogenous compound have been changed. The best results were reached in the reactions between the lower aldehydes and aniline. Thus, 75% alkylindoles were obtained from propanaldehyde and 62% from butyraldehyde. Also remarkable is the reaction between cyclopentanone and phenylhydrazine because 45% 2,3‐trimethyleneindole was obtained.
Mass spectrometric study of (CH3)4‐nSi(SCH3)n (n=1‐4) and (CH3)2Si(‐SCH2‐)2
Authors: Naessens L. A. , Claeys E. G. , Hoste S. , van Der Kelen G. P. 
Published: September 2010

AbstractThe mass spectra of the series (CH3)4‐nSi(SCH3)n (n=1‐4) and of (CH3)2Si(‐SCH2‐)2 were studied and the fragmentation processes under electron impact are discussed. The main features of the mass spectra are: (i) the high abundance of the molecular ions, (ii) the competitive loss of methyl and thiomethyl radicals from the molecular ions with formation of the base peak ions, (iii) the elimination of a number of neutral fragments as the most likely fragmentation process of the base peak ions.
Approaches Towards the Synthesis of Allenyl Azides
Authors: L'abbé Gerrit , Mahy Michel , Bollyn Marcus , Germain Gabriel , Scheefer Guy 
Published: September 2010

AbstractMethods which are known to produce allenes under mild conditions have failed to synthesize the yet unknown title compounds. These are (i) azide substitution of propargyl sulfonates, (ii) reactions of α‐azido acid chlorides with ynamines, and (iii) Wittig condensation of α‐azido acid chlorides with phosphorus ylides. The reaction products obtained are respectively azidoalkyl‐1, 2, 3‐triazoles (4), pyrrolinones (6) or pyridines (8), and a disubstituted ylide (11) or the fused triazole 12.
Synthèse, Par la Méthode de Hewett, Des Benzo [a]Naphto[2,1‐j]Anthracéne, Naphto[2,1‐c]Chrysene, Benzo[a]Picéne et 8,16‐Diméthoxycarbonylbenzo[c] Naphto [2,1‐1] Chrysene
Authors: Brison Jean , Martin Richard H. 
Published: September 2010

AbstractSynthesis, by Hewett's method, of benzo[a] naphtho [2,1‐j]anthracene, naphtho[2,1‐c]chrysene, benzo[a]picene and 8,16‐dimethoxycarbonylbenzo[c] naphtho[2,1‐1]chrysene. The title compounds 8b, 9b and 10b were obtained by potash fusion of α‐(1‐bromo‐2‐naphthyl)‐β‐(2‐phenanthryl) acrylic acid (7) followed by decarboxylation. The dicarboxylic ester 13 was prepared a. by potash fusion of 12a and 12b followed by esterification b. by the double photocyclisation of the dimethyl esters 12b and 12c.
Synthèse Photochimique D'Hydrocarbures Polycycliques Aromatiques et Étude en RMN‐1H Des Protons de Baie. Effets de Solvant Specifiques et Effets Nucleaires Overhauser
Authors: Brison Jean , De Bakker Claude , Defay Nicole , Geerts‐Evrard France , Marchant Marie‐Jeanne , Martin Richard H. 
Published: September 2010

Abstract“Photochemical synthesis of polycyclic aromatic hydrocarbons and NMR‐1H study of bay protons. Specific solvent effects and nuclear Overhauser effects”. Dinaphtho[1,2‐a 2′,1′‐j]anthracene (4a), 9‐bromo‐dinaphto [1,2‐a; 2′,1′‐j]anthracene (4b), 9‐methyldinaphtho[1,2‐a; 2′,1′‐j]anthracene (4c), benzo [c]naphtho [2,1‐1]chrysene (7), benzo [a]naphtho [2,1‐j]anthracene (3), naphtho [2,1‐c]chrysene (9) and dibenzo [c,1] chrysene (12) have been synthesized by the photocyclodehydrogenation of 1,2‐diarylethylenes (5,8) and bis (arylvinyl)arenes (6, 10). The NMR study has been mainly focused on the bay protons involved in specific solvent effects (Table 4) and nuclear Overhauser effects (Table 5).
Carbon‐13 Chemical Shifts of Three Oxo‐, Six Monohydroxy‐, and Four Dihydroxycyclohexyl Derivatives of Trihexyphenidyl
Authors: Paeme G. , Grimée R. , Vercruysse A. 
Published: September 2010

AbstractA number of oxo‐, monohydroxy‐ and dihydroxycyclohexyl derivatives of trihexyphenidyl were synthetised as potential metabolites of this drug in the rat. They were identified by 13C‐NMR spectroscopy.
Preparative Investigations of Bromoarsenate (III) Complexes
Authors: Rizvi S. S. A. 
Published: September 2010

AbstractThe reaction of AsBr3 with different amine hydrobromides were studied in aqueous hydrobromic acid (48 %) medium. A few of these compounds were prepared by Popov (1) in chloroform medium. Two types of complexes like 1:1 and 2:3 were prepared. Arsenic, nitrogen, bromine, carbon and hydrogen have been estimated and chemical nomenclature suggested.
EnzymaticIn VitroReduction of Ketones. Part 111. The Unexpected Steric Course of the HLAD Catalyzed Reduction of 3‐Cyanocyclohexanone
Authors: Willaert Jan J. , Lemière Guy L. , Dommisse Roger A. , Lepoivre Joseph A. , Alderweireldt Frank C. 
Published: September 2010

Abstract3‐Cyanocyclohexanone is a suitable substrate for preparative HLAD reduction, delivering enantiomerically pure (1S, 3S)‐transand (1R, 3S)‐cis‐alcohols. Details are given on the kinetics of the reduction and the absolute configuration of the products.In contrast to recently developed reaction models an important amount of (1R,3S)‐cis‐alcohol is formed.Some side reactions of the substrate with the TRIS‐buffered medium are described.
Une Nouvelle Methode De Bromation: Le Tribromure De Tetrabutylammonium
Authors: Fournier M. , Fournier F. , Berthelot J. 
Published: September 2010

AbstractTetrabutylammonium tribromide (TBA Br3) is used under mild conditions as bromating agent for the addition on double bonds of alkenes and for selective α‐substitution of acetals in high yields.
NMR Studies on Imidines. IV.H and 13C Nuclear Magnetic Resonance Study of Tautomerism in 2‐Aminopyrrolin‐5‐One
Authors: Spiessens Luc I. , Anteunis Marc J. O. 
Published: September 2010

Abstract2‐Aminopyrrolin‐5‐one (2) is shown to be present in solution as the amino tautomer 2a by 13C NMR chemical shift comparison with model compounds: 2‐(dimethylamino) pyrrolin‐5‐one (5), 2,3,4‐trihydropyrrolidino [1,2‐a] pyrimidin‐6‐one (6) and (E)‐1‐methyl‐5‐methylimino‐2‐pyrrolidinone (7). Their syntheses are described and extensive 1H and 13C NMR data are given. The monomethyl derivative of 2, 2‐(methylamino) pyrrolidin‐5‐one (8), is similarly shown to be an amino tautomer and is present in solution as a mixture of Z and E isomers with respect to the hindered rotation around the exocyclic C‐N bond. It is suggested that succinimidine is best represented by the 2‐amino‐5‐iminopyrroline structure (1a).
NMR Studies on Imidines. V. 1H and 13C Nuclear Magnetic Resonance Study of the Tautomerism and Geometrical Isomerism of 1,3‐Bis(Arylimino)Isoindolines
Authors: Spiessens Luc I. , Anteunis Marc J. O. 
Published: September 2010

AbstractDetailed 1H and 13C NMR data are given for a series of 1,3‐bis(arylimino) isoindolines [aryl = phenyl (2), p‐tolyl (3), p‐methoxyphenyl (4) and 2‐pyridyl (5)] and for two N‐methyl derivatives: 1,3‐bis(phenylimino)‐2‐methylisoindoline (6) and 3‐N,N‐methyl, p‐tolyamino‐1‐(p‐tolylimino)‐1H‐isoindole (7). The diimino form is shown to be the predominant tautomer in compounds 2 – 5 by 13C chemical shift comparison with model compounds 6 and 7. Geometrical isomerism about the exocyclic C=N (C‐N) bonds is discussed. The imino model 6 adopts the EE configuration exclusively. The amino model 7 is present in a 90:10 ZE:EE ratio with respect to the p‐tolylimino substituent at C‐1. Compounds 2 – 4 show a mixture of ZZ and ZE isomers in a ratio of about 70:30. The bis‐pyridyl derivative 5 is present exclusively as the ZZ geometrical isomer due to an intramolecular hydrogen bond bridging mechanism.
New Trinervitane Diterpenes from NEO ‐ GuineanNasutitermessp.(1)
Authors: Braekman J. C. , Daloze D. , Dupont A. , Pasteels J. M. , Ottinger R. 
Published: September 2010

AbstractFour new 1 (15),8 (19)‐trinervitadiene derivatives have been isolated from nasute termite soldiers from Papua‐New Guinea and their structures determined on the basis of their spectral properties. They have been identified as 9β‐acetoxy‐2β,3α‐dihydroxy‐1 (15),8 (19)‐trinervitadiene (1), 2β,3α,9α, 13β‐tetraacetoxy‐1 (15),8 (19)‐trinervitadiene (2) and 2β,3α,9α,13β‐tetraacetoxy‐1 (15),8 (19)‐trinervitadienes (3 and 4). These last two derivatives are epimeric at C‐11. The configurations at C‐9 and C‐13 of 8, a previously isolated tetraacetate, are also assigned.
Structure du chlorotris (1,4,7‐trimethylindenyl) uranium
Authors: Meunier‐Piret J. , van Meerssche M. 
Published: September 2010

AbstractThe crystal structure of Chlorotris (1,4,7‐trimethylindenyl) uranium was determined from three‐dimensional X‐ray data. [U(C12H13)3Cl] crystallizes in space groupP21/c witha= 9.763(4),b= 16.480(11), c = 18.763(10)Å, β = 101.07(4)° andDx= 1.670 Mg cm−1forZ= 4. The structure was solved by the heavy‐atom method. The U‐atom is π‐bonded to C5‐ring of the indenyl ligand and has a distorted tetrahedral environment. The structures of [U(C12H13)3Cl] and [Th(C12H13)3Cl] are isomorphous.
Novel Synthetic Approaches to Monocyclic β‐Lactam Antibiotics
Authors: Hanessian Stephen , Sahoo Soumya P. , Couture Claude , Wyss Heinz 
Published: September 2010

AbstractAccess to optically active 3‐ and 3,4‐substituted azetidinones and to β‐substituted amino acids is reported with applications in the area of monobactam antibiotics.
Catalytic Functionalities of Supported Sulfides III. Correlation of activities at Elevated Pressure with Oxygen Chemisorption
Authors: Liu Y. , Massoth F. E. , Shabtai Joseph 
Published: September 2010

AbstractA number of different supported CoMo catalysts, that had been characterized by O2chemisorption measurements, were evaluated for hydrodesulfurization of dibenzothiophene, hydrogenation of naphthalene, and C‐N‐bond hydrogenolysis of indole at elevated pressure. Only rough correlations between the different catalyst functionalities, and between the functionalities and O2chemisorption, were obtained. It is concluded that different active sites are involved for the different reactions, and that O2chemisorption is generally related to the dispersion of the active MoS2phase rather than to any specific reaction site.
Fast and Slow Steps of Hydrodesulfurization
Authors: Schulz Hans , Do Dac‐Vong 
Published: September 2010

AbstractTwo model mixtures (2‐methylthiophene, phenol, o‐toluidine, ethylbenzene and benzothiophene, o‐cresol, aniline, o‐xylene) were used to characterize activity and selectivity of different sulfur resistant catalysts for simultaneous HDS, HDO, HDN and hydrogenation of aromatics. 2‐methyltetrahydrothiophene and dihydrobenzothiophene were found as intermediates. A mechanism for the HDS‐reaction is discussed and compared to the HDN mechanism of quinoline.
Carbon‐Supported Iron Sulfide Catalysts
Authors: Groot C. K. , van Der Kraan A. M. , De Beer V. H. J. , Prins R. 
Published: September 2010

AbstractCarbon‐supported iron sulfide catalysts were characterized by means of thiophene hydrodesulfurization and butene hydrogenation activity measurements in a flow micro reactor, operating at atmospheric pressure. The iron content was varied from 0.03–1.9 Fe atoms per nm2 support surface area (0.3–17.7 wt% Fe). Oxidic catalyst precursor systems were dried either at 293K, or at 293K and subsequently at 383K.Dispersion of the oxidic iron phase present in the dried catalyst precursors and in the reoxidized sulfided catalysts was determined by Mössbauer spectroscopy, while X‐ray photoelectron spectroscopy was used for characterization of oxidic and sulfided catalysts.Carbon‐supported iron sulfide catalysts had a much higher HDS activity than alumina‐supported ones. They were also more active and less sensitive to deactivation than carbon‐supported molybdenum sulfide catalysts, which were the better hydrogenation catalysts.Drying of oxidic iron catalyst precursors at 383K caused a significant sintering and a lower catalytic activity. Sintering was also observed to occur during catalyst presulfiding. The extent of sintering appeared to increase with surface loading. The oxidic iron phase of the freshly prepared catalyst precursors dried at 293K consisted mainly of small iron(III) oxide particles (<40 A), which were, at least at low surface loadings, inhomogeneously distributed over the support surface.Iron(II) sulfide was found to be the main active phase. It was also noticed that considerable amounts of elemental sulfur are formed during sulfiding.
Characterization of Sulfided Ni‐Mo/γ‐Al2O3 Catalysts by O2 and NO Chemisorption. Influence of the Method of Preparation
Authors: Agudo A. LÓPez , Gil Llambías F. J. , Tascón J. M. D. , Fierro J. L. G. 
Published: September 2010

AbstractTwo Ni‐Mo/γ‐Al2O3 catalyst series prepared by sequential or simultaneous impregnation with a Mo content of ca. 8 wt% MoO3 and NiO content ranging between 0 and 8.9 wt% were studied in their sulfided state. Quantitative determination of irreversible chemisorption of NO at room temperature and of O2 at ‐78°C indicated that NO uptake was much higher than that of O2 for both catalyst series. Besides, NO uptake increased with promoter content until Ni/Mo ca. 0.8 and then leveled off, whereas O2 uptake steadily increased with increasing Ni/Mo ratios. Absorbance of IR band of NO chemisorbed on Ni atoms at 1840–1845 cm−1 were always higher for the sequentially impregnated catalysts. The absorbance of NO in both series vs. Ni/Mo ratio followed volcano‐type curves, such as those found for hydrodesulfurization (HDS) activity. A possible correlation between HDS activity and both, NO‐ and O2‐ uptake and NO absorbance on Ni atoms is attempted.
A Geometrical Model of Hydrotreating Catalysts ‐ Prediction of Catalytic Activity Variations with Composition
Authors: Kasztelan S. , Toulhoat H. , Grimblot J. , Bonnelle J. P. 
Published: September 2010

AbstractA geometrical model of the active phase of hydrotreating catalysts is proposed. The existence of MoS2 patches on a carrier and the reactivity of the edge sites of these patches are the two experimental observations used for the development of this model. The promotor effect is taken into account by an edge decoration of the patches. A partial loss of promotor ions into the Al2O3 carrier and formation of a promotor bulk sulphide are also considered. The specific activity for a given reaction, the amount of chemisorbed oxygen and promotor effect are predicted and can be compared to experimental results previously published in the literature by different authors. The good fitting obtained put in evidence that both HDS, hydrogenation and O2 chemisorption Involve the edge sites (unpromoted or promoted) of the patches. The model has a general character and may apply to MoS2 or WS2, promoted or unpromoted, supported and unsupported hydrotreating catalysts.
Carbon ‐ Supported Transition Metal Sulfides
Authors: Vissers J. P. R. , Groot C. K. , van Oers E. M. , Beer De , Prins R. 
Published: September 2010

AbstractFirst, second and third row transition metal sulfides ranging from group VI to group VIII c, supported on activated carbon were evaluated for their ability to catalyze the hydrodesulfurization of thiophene at atmospheric pressure. X‐ray photoelectron spectroscopy was used to measure the chemical state and to obtain an indication of the dispersion of the supported sulfide particles. Second and third row elements display volcano curves with catalytic activity varying over more than an order of magnitude and maxima occuring at Rh in the second and Ir in the third row. First row elements show a twin‐shaped pattern with maximum activity located at Cr and Co. The resemblance of these experimental activity trends with those previously reported for unsupported transition metal sulfides demonstrate the advantage of carbon supports in studies on the intrinsic catalytic properties of small sulfide particles. A correlation between the catalytic activity of second and third row elements and the shift in XPS binding energies between metal and metal sulfide phases was found. Superior catalysts have low binding energy shifts and preserve a high degree of metal character under sulfiding conditions.
Quantum Chemical Studies of the Adsorption of Thiophene on MOS2 Hydroprocessing Sites
Authors: Joffre J. , Lerner D. A. , Geneste P. 
Published: September 2010

AbstractThe modelisation of an HDS site from the MoS2 structure is undertaken in order to understand the desulfurisation of thiophene. Depending on the number of coordinative unsaturation degrees (one, two and three anionic vacancies) and on their stoechiometry (Mo3S13H12”, MOS5H5”, MOS5H4”, MOS4H4 and MOS3H3+) these models may represent sites on basal planes, edges, or corners of the MOS2 crystal.Different types of adsorption (vertical, horizontal, on S, on the hetero‐cycle and on one pi bond) of the thiophene molecule on the different model sites are computed using the EHT quantum chemical method. The comparison of the adsorption energy curves obtained by approaching thiophene near the site shows that the vertical one point adsorption of the S atom of thiophene is prefered over any. This adsorption step can be readily followed by a desulfurization process supposing C4H4 radical is an intermediate. These theoretical predictions agree with different conclusions of the literature. The MOS4H4 model seems to be the best choice for the site.
Practical Synthesis of 2,2,5,5‐Tetrachloro‐1,6‐Hexanedioic Acid, from Trans‐1,2‐Cyclohexanediol or Cyclohexanone, Involving Oxidation of 3,3,6,6‐Tetrachloro‐1,2‐Cyclohexanedione
Authors: Buyck Laurent De , Vanslembrouck Jan , Kimpe Norbert De , Verhé Roland , Schamp Niceas 
Published: September 2010

AbstractTrans‐1,2‐cyclohexanediol was quantitatively converted into 3,3,6,6‐tetrachloro‐1,2‐cyclohexanedione (2) by treatment with chlorine in dimethylformamide. The hydrate of the dione was oxidized by aqueous potassium permanganate to afford the title acid 1 in 91% overall yield. An alternative low cost preparation was elaborated, providing 2 in 61–74% yield starting from cyclohexanone in a three step procedure without isolation of intermediates. The reaction sequence involves substitution of α‐dichloro‐ and trichlorocyclohexanones by sodium acetate in acetic acid and chlorination of the resulting 2‐hydroxy‐ and 2‐acetoxy‐2‐cyclohexenones in dimethylformamide.
Conformational Analysis of Trans and CIS Isomers of N‐Trifluoroacetyl‐2‐Methoxy‐4‐t. Butylpiperidine and N‐Trifluoroacetyl‐2‐Methoxy‐4‐Methyl Piperidine
Authors: Duquet Dirk , Callens Roland E. A. , Anteunis Marc J. O. , Borremans Frans A. M. 
Published: September 2010

AbstractThe solution conformation of both Z and E rotamers of trans and cis isomers of N‐trifluoroacetyl‐2‐methoxy‐4‐t.butylpiperidine and N‐trifluoroacetyl‐2‐methoxy‐4‐methylpiperidine is determined from a complete analysis and assignment of proton and carbon nuclear magnetic resonance data. The trans isomers have chair conformations and a Z/E amide bond rotation barrier of ca. 76 kJ.mol−1. The cis 4‐t.butyl analogue is a flexible D2 twist with the two‐fold symmetry axis through Cα,Cδ for the Z rotamer, but rather through Cβ,Cε for the E rotamer, with a lowered interconversion barrier of ca. 63 kJ.mol−1. The cis 4‐methyl compound is a greatly distorted chair with a Z/E activation barrier of ca. 65 kJ.mol−1. These results are relevant in relation to the potential importance of twist‐boat cyclic imino acids as β‐bend inducing entities in synthetic peptides.
Transition‐Metal‐Catalysed Reactions of Diazoesters. Insertion into C‐H Bonds of Paraffins Catalysed by Bulky Rhodium(II) Carboxylates: Enhanced Attack on Primary C‐H Bonds
Authors: Demonceau A. , Noels A. F. , Hubert A. J. , Teyssié P. 
Published: September 2010

AbstractRhodium(II) carboxylates associated with bulky ligands catalyse the insertion of carbalkoxycarbenes (generated from diszoesters) into C‐H bonds of normal and branched alkanes with selectivities differing substantially from those associated with non‐bulky carboxylates.
Effets de la Substitution Captodative XXX1. Addition Des Radicaux Dérivés de Cétones, D'Aldéhydes et de Formiates À L'α‐Tert‐Butylthioacrylonitrile2
Authors: Mignani S. , Merényi R. , Janousek Z. , Viehe H. G. 
Published: September 2010

AbstractOxydation of ketones, aldehydes and formiates in the presence of radicophilic olefin α‐tert‐butylthioacrylonitrile 3 with captodative (cd) substitution does not give the usual radical decay products: The radical adducts dimerize, thus building a four carbon‐bridge between the original radicals R°.
Iminoalkylation Des Ènamines Avec Des Nitriles Via Le Sel De Nitrilium: Une Nouvelle Méthode De Synthèse D'Ènaminocétones Et De β‐Dicétones.
Authors: Baudoux Dominique , Fuks Robert 
Published: September 2010

AbstractThe reaction of nitrilium salts with enamines leads to a mixture of enaminimines 4 and enaminoketones 5 by an iminoalkylation reaction. Partial hydrolysis of 4 with diluted acetic acid leads to the isolation of these new enaminoketones 5 in high yields. Refluxing them in HCl 6 N give β‐diketones, well described and usually obtained by acylation of enamines with acid chlorides. The nitrilium salt being easily prepared “in situ” from the corresponding nitrile this reaction constitutes a novel way to enaminoketones 5 and β‐diketones 6. A nitrilium salt being a much stronger electrophile than an acid chloride, the experimental conditions are milder and do not need the presence of triethylamine. The scope and limits of this novel reaction in relation to the nature of the starting nitrile are discussed.
Synthesis, Characterisation and Anti‐Tumour Activity of Bis(Polyfluoroalkyl)Tin Dihalides
Authors: Clercq Ludo De , Willem Rudolph , Gielen Marcel , Atassi Ghanem 
Published: September 2010

AbstractThe synthesis and characterisation of fifteen new organotin compounds containing at least two CF3(CF2)5CH2‐CH2 groups bound to tin are described. The activity of six of these compounds towards the murine P388 lymphocytic leukaemia tumour is given.
Redox Polymerization. Kinetics of the Reaction Initiated by Dimethyl Sulphoxide Ce(IV) System In HClO4 Medium
Authors: Nageswar Rao K. , Sethuram B. , Navaneeth Rao T. 
Published: September 2010

AbstractThe kinetics of polymerization of acrylonitrile (AN) initiated by ceric perchlorate‐dimethyl sulphoxide (DMSO) redox system has been found to be proportional to (a) square of [AN], (b) the [DMSO] and (c) independent of [Ce(IV)]. The rate of ceric disappearance is found to be proportional to the [Ce(IV)], fractional power of [DMSO]. A kinetic scheme has been proposed whereby both the ceric ion and the radicals produced from the oxidation of DMSO by ceric ion have been shown to initiate the polymerization while the termination occurs exclusively by the interaction of chain radicals with ceric ions.