bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ce(III), Th(IV), U(VI), La(III) and Y(III) chelates with arylidene salicylichydrazide. The micro‐analytical determination of these metals
Authors: Temerk Y. M. , Ahmed Z. A. 
Published: September 2010

AbstractThe complexes formed between arylidene salicylichydrazide and Ce(III), Th(IV), U(VI), La(III) and Y(III) have been investigated using spectrophotometric and conductometric method. The study revealed the formation of complexes having the metal: ligand ratios 1:1 and 1:2. The values of log β for the different complexes are determined. The mode of bonding of the ligands in the solid chelates were studied by IR spectrophotometry which showed that chelate formation takes place through the CO and CH groups. The high stability constants and absorptivity coefficients of metal complexes indicate that micro amounts of the metal ions investigated can be determined spectrophotometrically with fair accuracy.
Facile synthesis of dihydrobenzo[a]xanthone derivatives
Authors: Verhé R. , De Buyck L. , De Kirape N. , De Wispelaere W. , Schamp N. 
Published: September 2010

AbstractA series of dihydrobenzo [a] xanthone derivatives has been prepared by thermal condensation of 2‐ethoxycarbonyl‐3,4‐dihydro‐[1H]‐naphtalene‐1‐one and 1‐ethoxycarbonyl‐3, 4‐dihydro‐[2H]‐naphtalene‐2‐one with phenolic substrates.
Structure de l'acide N‐Acetyl‐L‐Thiazolidinecarboxylique‐4 C6H9NO3S
Authors: Tinant B. , Declercq J. P. 
Published: September 2010

AbstractFran X‐ray analysis, conformation and molecular structure of N‐acetyl‐L‐thiazolidine‐4 ‐carboxylic acid has been determined. The conformation of the thiazolidine ring is that of an envelope β−. Crystal data are as follow: monoclinic, P21; a = 6.402(5), b = 10.382(7), c = 6.234 (5)Å, β = 105.56(7)°, V = 399.2 Å3, Z = 2, Dx = 1.46 Mg m−3.
Hydroxamic Acids in Gravimetric Analysis
Authors: Agrawal Y. K. , Roshania R. D. 
Published: September 2010

AbstractThe analytical potentialities of hydroxamic acids as reagents for gravimetric determination of aluminium, antimony, barium, beryllium, bismuth, cadmium, cerium, cobalt, copper, dysprosium, erbium, gadolinium, gallium, indium, iron, lanthanum, magnesium, mercury, molybdenum, neodymium, nickel, niobium, praseodymium, samarium, scandium, tantalum, thorium, tin, titanium, tungsten, terbium, uranium, vanadium, yttrium, zinc and zirconium are reviewed.
The thermal decomposition of cu(II) complex of 3,5‐dinitrosalicylic acid
Authors: Heda B. D. , Khadikar P. V. 
Published: September 2010

AbstractThe thermal decomposition of Cu(II) complex of 3,5‐dinitrosalicylic acid is studied by the TG, DTG, and DTA. The complex decomposes in the temperature range 100‐560°C with explosion at 280°C giving a low CuO content.
Use Of Calculated Carbon Chemical Shift Tables Of Saturated C‐7 To C‐Ll Sterol Side Chains For Structure Elucidation
Authors: Kelecom A. 
Published: September 2010

AbstractThe 13C NMR chemical shifts of C‐7 to C‐11 saturated sterol side chains have been calculated both by the LINDEMAN & ADAMS and by the GRANT & PAUL equations. The results have been compared with published data. Attributions of the literature have been revised. Calculated data presented allow convenient characterization of C‐7 to C‐ll saturated sterol side chains.
Charge Transfer Complexes of Crown Ethers with 2, 3, 5, 6 ‐ Tetracyano Pyrazine
Authors: Malini R. , Krishnan V. 
Published: September 2010

AbstractThe interaction of five crown ethers, 15‐crown‐5, 18‐crown‐6, benzo‐15‐crown‐5, dibenzo‐l8‐crown‐6, and dibenzo‐24‐crown‐8 with 2, 3, 5, 6 ‐ tetracyano pyrazine has been studied by spectroscopic methods. The association constants and thermodynamic parameters of the 1:1 complexes formed by donor ethers with the acceptor have been evaluated. There is an indication that oxygens of the ethers and aryl part of the ether act cooperatively in binding of the acceptor.
Structure de deux dérivés hydantoïniques de la proline: La l‐proline hydantoïne C6H8N2O2 et la d‐allohydroxyproline hydantoïne C6H8N2O3
Authors: Arte E. , Tinant B. , Decleroq J. P. , Germain G. , van Meerssche M. 
Published: September 2010

AbstractThe structure of L‐proline hydantoin(I) and D‐allohydroxyproline hydantoin(II) have been investigated using X‐ray diffractometer intensities. The conformation of proline ring is β+ for (I) and γ+ for (II). The deviations from planearity in the two hydantoins rings are not negligeable.Crystal data are as follow (I) orthorhombic, P212121; a = 11.379(5), b = 8.009(3), c = 7.131(3) Å; V = 649.9 Å3; Z = 4; Dx = 1.43 Mg m–3.
Enzymatic “In Vitro” Reduction of Ketones VII.(1) Reduction rates and stereochemistry of the HLAD catalyzed reduction of 2‐alkyl cyclohexanones, dimethyl cyclohexanones, cycloalkanones and bicycloalkanones
Authors: van Osselaer T. A. , Lemière G. L. , Lepoivre J. A. , Alderweireldt F. C. 
Published: September 2010

AbstractValues for the rate constants of the catalytic step HLAD‐NADH + ketone → HLAD‐NAD+ alcohol in the HLAD catalyzed reduction of some 2‐alkyl cyclohexanones, geminal dimethyl cyclohexanones, cycloalkanones and bicyclic ketones are presented. Also the thermodynamic parameters of activation are given and they are compared with the activation parameters of the NaBH4 reduction leading to a better understanding of some forces at work in enzymatic catalysis. The results are rationalized in the same way as was previously done for the 3‐alkyl and 4‐alkyl cyclohexanones. A reaction model is obtained in which steric hindrances and hydrophobic zones are responsible for rate decreasing, respectively increasing interactions between enzyme and substrates.
The breaking of molecular point group symmetry
Authors: Bunker P. R. 
Published: September 2010

AbstractIn this review paper the definition of the elements of the molecular point group are carefully considered. It is shown that certain terms in the molecular Hamiltonian are not invariant to these operations and, hence, these terms can break the point group symmetry. The symmetry labelling of the energy levels of H2, H2O and CH4 are studied in detail in order to demonstrate this point. It is shown that the rotational energy levels of molecules can be satisfactorily labelled using the Complete Nuclear Permutation Inversion Group or the Molecular Symmetry Group as appropriate.
Specific interactions between pyridines and tetrachloromethane or benzene
Authors: Huyskens P. , Mahillon PH. 
Published: September 2010

AbstractThe integral enthalpies of solution ΔHsol of pyridines were determined at a mole fraction xB of 0.03 in cyclohexane, tetrachloromethane and benzene. The dipole moments of these bases were also determined. The differences ΔHsol (C6H12) ‐ ΔHsol (CCl4) and ΔHsol (C6H12) ‐ ΔHsol (C6H6) increase with the pKa of the pyridines in water. This is also the case for the difference μB (CCl4) ‐ μB (C6H12). However there is no marked difference between the moments in C6H6 and C6H12. These results confirm the theory of Dumas and Gomel concerning the acceptor character of CCl4. They show further that, near (δ, σ) interactions between the π‐electrons of pyridine and CCl4, interactions of the n‐σ type involving the n‐electrons of the pyridine nitrogen atom play also an important role. However the intervention of n‐electrons in the specific interactions between pyridine and benzene remains negligible, these interactions being chiefly of the π‐π type.
Structure de deux dérivés hydantoïnes: La L‐hydantoïno [c] perhydrothiazine‐1, 4 C6H8N2O2S et la L‐N‐méthylhydantoino [c] perhydrothiazine‐1, 4 C7H10N2O2S
Authors: Tinant Bernard , Declercq Jean‐Paul , Germain Gabriel , Meerssche Maurice Van 
Published: September 2010

AbstractThe structure of L‐hydantoïno [c]‐1, 4‐perhydrothiazine (I) and L‐N‐methyl‐hydantoïno [c]‐1, 4‐perhydrothiazine (II) have been investigated using X‐ray diffractometer intensities.Crystal data are as follow (I) orthorhombic, P212121, a = 6.106 (6), b = 5.217 (4), c = 22.725 (19) Å, V = 723.9 Å3, Z = 4. (II) orthorhombic, P212121, a = 5.616 (2), b = 9.414 (2), c = 16.444 (6) Å, V = 869.4 Å3, Z = 4.
Organometallic chemistry of metal surfaces ‐ ultra high vacuum studies
Authors: Muetterties E. L. , Tsai Min‐Chi 
Published: September 2010

AbstractThe effect of one type of molecule on another for chemisorption states on a platinum (111) surface is described. This effect was assayed from chemical displacement and thermal desorption experiments. Molecules studied in this fashion included CH3CN, CH3NC, C5H5N, P(CH3)3, CO, PF3, C6H6, and C2H4. The chemistry of Pt(111) is generally distinct from that of Ni(111) in both a qualitative and quantitative fashion.
Electron spin resonance and kinetic studies on tin centered radicals r3sn. with bulky substituents
Authors: Lehnig M. , Buschhaus H.‐U. , Neumann W. P. , Apoussidis TH. 
Published: September 2010

AbstractESR data of stannyl radicals R3Sn. with residues R of considerable bulkiness in solution are presented. With R = neophyl (PhMe2C‐CH2), (g = 2.0150) an alternating linewidth effect indicating hindered rotation around the Sn‐C bonds is found. The radical is non‐planar by 14.0° and configurationally stable. The radicals (2, 4, 6‐alkyl3Ph) Sn., alkyl = H, Me, Et, i‐Pr show singlets (g = 2.0023 ‐ 2.0078) broadened by unresolved hyperfine interactions with ring and alkyl protons, aH ≤ 0.05 mT. They are non‐planar by 15.1 – 16.1°, (i‐Pr3Ph)3Sn. being less pyramidal than Ph3Sn because of steric repulsions between the substituents, and are in recombination‐dissociation equilibria with the corresponding distannanes. The Sn‐Sn bond energies drop from 205 kj (alkyl = Me) to 36 kJ (alkyl = i‐Pr). For (Et3Ph)3Sn., the activation energy of recombination is 38 kJ/mol.
Stabilization by hydrogen bonds of ketones in water
Authors: Huyskens P. , Nauwelaerts F. 
Published: September 2010

AbstractThe distribution coefficients PB of 2‐propanone, 2‐butanone, 2‐ and 3‐pentanone and 2‐ and 3‐hexanone, between cyclohexane and water were determined at 298.16 K using U. V.‐spectrometry. These coefficients are related to the molar volume VB of the pure ketones by the relation: log PB = 0.87 + 0.029 VB ‐ b, the last parameter describing the effect of the hydrogen bonds between the dissolved ketones and the water molecules of the aqueous phase. For the ketones studied here b is approximately constant and equals 3.44±0.20. The effect is of the same order of magnitude as that observed for pyridine but is smaller than that given by triethylamine, and markedly larger than that observed for N, N disubstituted anilines. From these results it can be concluded that at room temperature the great majority of the ketone molecules dissolved in water from hydrogen bonds with the surroundings, the fraction of non hydrogen bonded molecules being only 3.6×10−4. The results also suggest that only one electron pair of the carbonyl group forms hydrogen bonds with the surrounding water molecules.
Polarography of aldoximes in buffer solutions
Authors: Damle M. V. , Kaushal R. , Tiwari M. , Malshe P. T. 
Published: September 2010

AbstractThe polarographic reduction of both isomers of benzaldoxime and furfurald‐oxime and the syn‐oximes of vanillin, O‐vanillin, p‐dimethylaminobenzaldehyde and salicylaldehyde have been studied in various buffers. It is observed that wave heights decrease upto pH 8.0, and the half‐wave potential shifts to more negative values. The reduction of the oxime possibly proceeds via the conjugate acid of the oxime(R‐CH: N‐OH) H+ at the electrode interface. The waves dis‐appear at pH>8, owing probably to the decreasing concentrations of H+ ions with increasing pH values. The mechanism of the reduction has been discussed.
An infrared study of the dimerization of trichloro‐ and tribromoacetic acid and their complexes with benzophenone
Authors: Synhaeve K. , Thijs C. , Zeegers‐Huyskens TH. 
Published: September 2010

AbstractThe dimerization of trichloroacetic (TCA) and tribromoacetic (TBA) acids and their interaction with benzophenone (BZ) are studied by infrared spectrometry in the 1800–1600 cm−1 range. In carbontetrachloride, at the temperature of 30°C, the dimerization constants of TCA and TBA are 210 and 295 dm3 mol−1. The equilibrium constants for the reaction TCA + BZ → TCA. BZ and TCA. BZ + TCA → (TCA)2. BZ are 150 and 21 dm3mol−1. For the interaction between TBA and BZ, these equilibrium constants are 123 and 60 dm3 mol−1. The influence of the concentration on the carbonyl bands of the acid and of the base, indicates that in the 1:2 complex, the two acid molecules are probably hydrogen bonded.
Triterpenoides de napoleonaea vogelii
Authors: Kapundu Mpuza , Warin R. , Delaude C. , Huls R. 
Published: September 2010

AbstractPerchloric hydrolysis of the seed saponin of Napoleonaea vogelii allowed the isolation of two prosapogenins. One of these was identified as napoleogenin. The structure of the second component has been established as 21β–|6 deoxy‐3, 4 diangelate‐β‐galactopyranosyl|oxy 3β, 16α, 22α, 24, 28 pentahydroxy‐olean‐12‐ene. The name “Napoleogenin B” is proposed for this new prosapogenin. On further hydrolysis this saponin yields protoaescigenin, isoaescigenin and aescigenin. The structure of napoleogenol previously obtained by hydrolysis of the saponin of Napoleonaea imperialis is revised and shown to be identical to aescigenin.
Polarographic behaviour of aldoximes in tetraalkyl halides
Authors: Damle M. V. , Tiwari M. , Malphe P. T. , Kaushal R. 
Published: September 2010

AbstractThe polarography of a few aromatic aldoximes has been studied in unbuffered 8% ethanolic medium using tetramethyl ammonium halides and tetraethyl ammonium iodide as supporting electrolytes (vs. S. C. E.). Some syn‐forms gave two step waves and the anti‐forms only one wave. On the basis of diffusion controlled waves of the two forms, we have concluded that the diffusion current constant “I” of the syn‐forms is 3 ± 0.3 and that of the anti‐forms 5 ± 0.5. In general if only one form of the oxime is available, one can find out its configuration by calculating the diffusion current constant.
Addition de l'acétone à des alcynes vrais fonctionnels ou non
Authors: Gardrat C. , Montaudon E. , Lalande R. 
Published: September 2010

AbstractAcetonyl radicals created by action of di‐t‐butylperoxide on acetone (molar ratios acetone/acetylenic compound/DTBP = 20/1/0.2; 150°C; 3h) add to acetylenic compounds and lead to the formation of 1/1 adducts in low to moderate yields. 2/1 adducts are not observed in these experimental conditions.
Assignment of 2, 3, 4 Acetylated Glycosides by the Lanthanide Induced “Cross‐Over” Phenomenon‐a Preliminary Investigation
Authors: Poncini L. 
Published: September 2010

AbstractThe “cross‐over” phenomenon induced by lanthanide shift reagents is investigated as a means for accurately assigning the 2, 3 and 4 ring O‐acetyl proton signals in the nuclear magnetic resonance spectrum of acetylated carbohydrates.
Chemical Composition of Airborne Particulate Matter in Belgium as Determined by Instrumental Neutron Activation Analysis
Authors: Demuynck M. , Dams R. 
Published: September 2010

AbstractDuring one year atmospheric aerosols have been collected daily at 14 stations in Belgium. Total suspended particulate levels, determined from all samples, indicated a high particulate pollution level for the major part of the country. Instrumental neutron activation analysis of 280 samples yielded significant concentration data for 29 elements and 10 additional components were determined in a limited number of samples only. Comparison to background levels and to concentrations in other polluted areas showed strong enrichments and an overwhelming anthropogenic contribution for most elements. On the basis of the time‐variability and the geometric distributions of the concentrations some intense sources could be localized and the elements could be divided in 5 groups with different sources, namely sea spray, coal combustion and steel production, liquid fuel combustion, siderurgical plants and non‐ferrous plants.
Secondary Ion Emission by Anionic Surfactants
Authors: Nelen A. , Tavernier S. , Saelens R. , Gijbels R. 
Published: September 2010

AbstractPositive secondary ion emission from anionic surfactant films on a gold substrate was mass spectrometrically studied under O2+bombardment. Signals from organic origin appear to be very sensitive to small variations in experimental parameters. The production of secondary metal ions (Na+, Mg+, K+, Ca+) is, however, quite reproducible. Their relative intensities drop exponentially with the first ionisation potential of the corresponding elements, yielding a so‐called plasma temperature in the range of 6500 to 8000 K. This suggests that the mechanism of secondary ion emission from adsorbed surfactants is essentially the same as for entirely different matrices. SIMS easily allows the detection of 10−14 g of adsorbed anionic surfactant via the metal counter ion.
Voltammetric Behaviour of the Ti(IV)/Ti(III) Couple at Glassy Carbon in H2SO4 Solutions
Authors: Kiekens P. , Vandenbruwaene J. , Temmerman E. 
Published: September 2010

AbstractThe voltammetric behaviour of the Ti(IV)/Ti(III) couple has been investigated at a glassy carbon electrode in sulphuric acid solutions. Only in highly concentrated acid solutions (CH2SO4 > 5 M) a reduction wave can be obtained that is separated from the hydrogen reduction wave. The Ti(III) oxidation produces a well‐defined irreversible wave from which some kinetic parameters were evaluated. However, the logarithmic analysis plot is curved. In all cases the apparent transfer coefficient and rate constant are found to be potential dependent. The oxidation reaction is calculated to be a first‐order one.
The Automatic Kinetic Determination of Iron (III) and Vitamine C
Authors: van Den Winkel P. , Mertens J. 
Published: September 2010

AbstractPrompt mixing of acetate buffered Iron(III) and ascorbic acid solutions results in the formation of a short‐lived colored [Fe3Ac6O] Asc complex showing a maximum absorbance at 550 nm. Mathematical analysis of the kinetics curves allows the elaboration of analytical procedures for the manual and automated determination of Iron(III) and vitamine C in a concentration range 0,1‐100 ppm and 1‐2000 ppm respectively.
Heteroaromatic Photosubstitutions
Authors: Párkányi Cyril 
Published: September 2010

AbstractPhotosubstitution reactions of π‐electron heterocycles are reviewed and discussed. The reactions are divided into four major types: a) free‐radical photosubstitutions, b) electrophilic photosubstitutions, c) nucleophilic photosubstitutions, and d) electron‐transfer assisted photoreductions and photodehalogenations. Examples are given for each of the four types. Photodehalogenations and electron‐transfer assisted photodehalogenations are then treated in detail.
Quantum Mechanical Studies of Atomic, Bond, and Molecular Polarizabilities: Application to Some Metal Hexacarbonyls of Octahedral Symmetry
Authors: Nagarajan G. 
Published: September 2010

AbstractA brief survey on the vibrational and structural studies has been made for the hexacarbonyls of chromium, molybdenum, and tungsten possessing an octahedral symmetry. The delta‐function potential model is developed and shown to be valuable in evaluating important quantities through the use of the vibrational method and the delta‐function electronic wave functions. It is then applied to the calculations of atomic polarizabilities, bond polarizabilities, contribution by the nonbonding electrons, bond perpendicular components of the polarisability, and the average molecular polarisability of both diatomic and polyatomic molecules. The delta‐function strengths, the values of the parameter c, and the atomic polaricabilities of all the atoms in the hexacarbonyls of chromium, molybdenum, and tungsten were calculated. The bond polaricabilities, contribution by the nonbonding electrons, bond perpendicular components, and average molecular polarisabilities were also calculated for these molecules. The results have been briefly discussed.
Search and Complete Listing of the Valence Structures of the Closo Boron Hydrides B9H and B10H
Authors: Gielen Marcel 
Published: September 2010

AbstractA systematic search has allowed to find 196 valence structures (VS) 2‐2‐for B9H and 728 for B10H instead of the 16 and 72 respectively described by Lipscomb(1).With these numbers of valence structures, (NVS), valence structure indexes (VSI) 2‐2‐ equal to 0.1637 and 0.1789 can be calculated for B9H and B10H resp. which are different from those determined by Aihara(4) (0.0860 and 0.1161 respectively).
Alternative Syntheses of 3,3,5‐Trimethyl‐1,2,4‐Cyclopentanetrione
Authors: Buyck Laurent De , Verhé Roland , Kimpe Norbert De , Courtheyn Dirk , Schamp Niceas 
Published: September 2010

AbstractEfficient procedures for the synthesis of 3,3,5‐trimethyl‐1,2,4‐cyclopentanetrione are described starting from the commercially available ketones 2,2,4‐trimethylcyclopentanone, 2,4,4‐trimethylcyclopentanone and 3,3,5‐trimethylcyclohexanone. The methods involve polychlorination and dehydrochlorination in dimethylformamide followed by hydrolysis.
X‐ray diffraction study of (±)‐decahydro‐9‐hydroxy‐9‐methylspiro|azuleno| 4,5‐b|furan‐6(2h),2'‐|1,3|dioxolan|‐2‐one (3aβ, 6aα, 9β, 9aβ, 9bα)
Authors: Declercq J. P. , Germain G. , van MEERSSCHE M. , Devreese A. , De Clerco P. , Vandewalle M. 
Published: September 2010

AbstractC15H22O5, monoclinic, P21/c, a=17.775 (5), b=7.932 (3), c=11.048 (4) Å, β=116.18 (3)º V=1397.9 (8) Å3, Z=4, Dx=1.34 Mg m−3. The structure has been solved by direct methods and refined to a final R value of 0.070 for 2253 observed reflections. The stereochemistry of the title compound is as depicted for one enantiomer in 1; the configuration of the asymmetric carbons can be specified as C(1)R, C(4)S, C(5)R, C(6)R and C(7)R. The cyclopentane and the lactone are envelopes with pseudomirror planes passing through C(5) and C(7), respectively. The seven‐membered ring adopts a conformation intermediate between a twist‐chair (C2 symmetry) and a chair (C8 symmetry) conformation.
Polymères Bioactifs X. Insolubilisation de la β‐Amylase sur des Dérivés de la Cellulose
Authors: Simionescu C. R. , Bouzaher Y. , Dumitriu S. 
Published: September 2010

AbstractInsolubilization of β‐amylase on cellulose carbonate and aminoaromatic derivatives of carboxymethylcellulose (CMC), such as N‐(4‐aminophenyl)‐CMC amide and N‐(4,4'‐diaminodibenzyl)‐CMC amide, is presented. The optimum coupling conditions depend on the nature of the carrier. By comparing the kinetic data for the reactions of insolubilized enzymes some conclusions are drawn regarding the influence of the support And of the binding mode on the activity of the coupled enzyme.
Étude du Comportement Chimique de Pyrano [2, 3‐c] Pyrazole‐3(2h)‐Ones Vis‐à‐Vis des Bases Azotées. II(f1). Réaction Avec Les Amines Aliphatiques
Authors: Maquestiau A. , van Haverbeke Y. , Vanden Eynde J.‐J. 
Published: September 2010

AbstractPyrano [2, 3‐c] pyrazole‐3 (2H)‐ones easily add aliphatic amines on the 6 position: the reaction is reversible. By prolonged heating and with primary amines only, the formation of alkylaminoethylidenepyrazolidin‐3, 5‐diones is observed.