bluuebunny/crossref_metadata_2025_split huggingface dataset:
Essais de Chloration Dirigée. XX: Etude des Réactivités Relatives Dans la Photochloration de Chloroalcanes
Authors: Gouverneur Par P. , Bruylants A. 
Published: September 2010

AbstractThe propyl, isopropyl, butyl, isobutyl, amyl, isoamyl and hexyl‐chlorides were submitted to photochlorination in the liquid phase at ordinary temperature in pure phase as wel in solvents. The relative reactivities (r. r.) observed in the presence of CS2 clearly shown that the influence of this solvent increases when the inductive effects on the reaction centers decrease. Furthermore, these r. r. permit to estimate how far in the aliphatic chain the influence of the chlorine substituent is extended. Finally, these r. r. are quantitatively analysed by means of the relationship:

.This latter takes into account the inductive, hyper conjugative and mesomeric effects.The results obtained at higher temperatures on the propyl, butyl, butylidène, amyl, isoamyl and hexylchlorides confirm that the bêtachloroalkyl radicals decompose by “vicinal effect” and that differences of activation energies between different positions are not important. Finally, the structure‐reactivity correlation obtained at 40° C is compared with the results observed at room temperature.
Tautomérie dans la Série des Pyrazolinones II. Influence Du Milieu Sur L'équilibre Prototropique Des Pyrazoline‐5‐Ones N1 Substituées
Authors: Maquestiau A. , van Haverbeke Y. , Jacquerye R. 
Published: September 2010

AbstractThe influence of solvent on the tautomerism on N1 substituted pyrazolin‐5‐ones has been investigated.As a general rule, the percentage of CH form is always bigger in apolar solvents and decreases in aprotic solvents with increasing basicity, probably in favour of the OH form.In protic solvents, the concentration of NH form is related with hydroxylic solvents acidity.
Cyclopentanones. VII on the synthesis of the rethrolones
Authors: Madeleyn E. , Vandewalle M. 
Published: September 2010

AbstractIn a previous paper a new synthesis of (±) allethrolone was described starting from 2‐methyl‐3,5,5‐triethoxy‐2‐cyclopentene‐l‐one. The applicability of this method for the synthesis of the natural rethrolones has now been investigated. The method is only suitable for the synthesis of (±) jasmololone.
Synthesis of α, β‐Unsaturated Ortho‐Hydroxy Aromatic Ketones by Fries Rearrangement of α, β‐Unsaturated Para‐Cresylesters
Authors: van De Sande C. , Vandewalle M. 
Published: September 2010

AbstractThe Fries rearrangement of α, β‐unsaturated para‐cresyl esters is reinvestigated. Spectroscopic data are included.
Les Complexes Par Transfert De Charge En Chimie Organique. VIII. Etude Thermodynamique Et Spectroscopique Des Complexes De L'anhydride Tetrachlorophtalique
Authors: Nagy J. B. , Nagy O. B. , Bruylants A. 
Published: September 2010

AbstractThe thermodynamic and spectroscopic properties of the charge‐transfer complexes formed by tetrachlorophtalic anhydride with various π electron donors were examined in 1, 2‐dichloroethane. In all cases only one complex of composition 1: 1 was detected. Several theoretical predictions were verified and it was shown that the entropy factor is neither constant nor proportionnaly varying with the enthalpy factor.The reliability of recently determined ionisation potential values for a large number of donors was also established.The charge‐transfer transition energies were found to satisfy the LCDA MO theory.
Potentiometric And Polarographic Determination Of The Stability Constants Of Bivalent Metal‐Itaconate Complexes
Authors: Robbrecht R. , Thun H. , Verbeek F. 
Published: September 2010

AbstractThe complexation between bivalent metal ions and itaconate was investigated potentiometrically at unit ionic strength in NaClO4 at 25.00±0.01°C in the pH region 2‐4.5. The complexes ML, ML2, MHL, MHL2 and MH2L2 can be identified and their stability constants calculated by both a graphical and a computer method. The results are in a good agreement with those obtained from polarographic measurements.
Preparative separation and isolation of three. Epimeric 2‐methylcycloalkanols by counter current distribution
Authors: Lemière G. L. , Dierckens J. J. , Alderweireldt F. C. 
Published: September 2010

AbstractDiastereoisomeric mixtures of 2‐methylcyclopentanol (I), 2‐methylcyclohexanol (II) and 2‐methylcycloheptanol (III) can be separated in very good yields into the cis and trans isomers by counter current distribution. A suitable method for isolation is also given.
Perturbation Theory and Stereoisomerization Modes
Authors: Brocas J. , Willem R. 
Published: September 2010

AbstractIt has been shown previously that the ratio of relaxation times is a characteristic of the modes of stereoisomerization for trigonal bipyramidal complexes. This result has been obtained under the assumption that all the rate constants for a given mode are the same. This equality is no longer true when the differences in chemical nature of the ligands are taken into account.In this paper, we describe a method, based on perturbation theory, in which this situation is studied. We show that, in the case where there are two ligands of type 1 and three of type 2, the situation where ligand 1 is more electronegative than 2 preserves the possibility of distinguishing the modes, by comparing the relaxation times.
Kinetics of Sulphonic Acid Catalyzed Acylations with Carboxylic Acid Anhydrides: Mixed Anhydrides as Intermediates
Authors: Joly L. , Hoornaert G. 
Published: September 2010

AbstractFrom a comparison of the kinetic behaviour in the sulphonic acid catalyzed acylation of anisole with carboxylic anhydrides and synthesized mixed anhydrides of them and the catalyst, the intervention of a mixed anhydride in the acylation with anhydrides has been proved.From a proposed reaction scheme a rate expression has been derived which is in agreement with all observations especially the pecularities observed for the kinetic behaviour of the anhydride and anisole.
Les Chlorures Basiques Mixtes de Zinc et de Cobalt
Authors: Mannoorettonijil M. , Glibert J. 
Published: September 2010

AbstractBy the addition of soda to a solution of ZnCl2 or CoCl2, the following compounds are precipitated: 4 Zn(OH)2. ZnCl2. I H2O (20 and 75°C), 4 Co(OH)2. Co(OH)0,6(Cl)I,4.4 H2O (20°C) and Co2(OH)3, 2(Cl)O,8.O,7 H2O (75°C). At 20°C, the two salts are isomorphous.In the mixed solution ZnCl2‐CoCl2, at 20°C, a continuous solid solution is formed characterized by a progressive variation of the basicity index between 33 and 63% Co. at. The distribution factor shows an important retention of zinc in the cobalt salt. At 75°C, the solubility of cobalt in the zinc tetrabasic chloride rises to 67% Co. at. A zone of demixtion separates the latter from the compound of cobalt which contains a maximum of 6,5% Zn. at.
Spectrométrie de Masse de Pyrazoline‐5‐Ones N1 Substituées. 1. 5‐AlkoXypyrazoles et 3‐Pyrazoline‐5‐Ones A Structures Fixes
Authors: Maquestiau A. , van Haverbeke Y. , Bruyere A. 
Published: September 2010

AbstractThe mass spectra of fixed pyrazolin‐5‐ones (5‐alkoxypyrazoles and 3‐pyrazolin‐5‐ones) are reported and discussed. Mass spectrometry allows characterization of these two isomeric structures.
Charge‐transfer complexes in organic chemistry. X. Solvent effects on spectroscopic and thermo‐dynamic properties of the complex acenaphtene‐tetrachlorophthalic anhydride
Authors: Nagy O. B. , Nagy J. B. , Bruylants A. 
Published: September 2010

AbstractThermodynamic and spectroscopic properties of the charge‐transfer complex acenaphtene‐tetrachlorophtalic anhydride were studied in different solvents. The corresponding thermodynamic and spectroscopic parameters were corrected for solvent competition. Only in this case were correlations obtained in agreement with theory. The solvents were divided into several classes such as aromatic, aromatic with one functional group, halogen containing and n‐donor solvents. The role of general and specific solvent effects is emphasized.
Nouvelles Données Structurales et Spectre Vibrationnel de Composés AB(XO4)2 Dérivant du Type Scheelite
Authors: Paques‐Ledent Marie‐Thérèse 
Published: September 2010

AbstractUne série de tungstates et molybdates doubles de formule AIBIII(XO4)2 appartiennent au type de la scheelite CaWO4.De nouvelles données obtenues parallèlement par diffraction X et par spectrométrie vibrationnelle pour un grand nombre de ces composés, indiquent que la symétrie des groupes tétraédriques XO4 est plus basse dans ces composés doubles que dans les scheelites simples. D'autre part, le spectre vibrationnel dans le domaine des vibrations relatives aux groupes XO4, ne peut être interprété sur base d'une maille élémentaire de symétrie C4h.
Complexes par Transfert de Charge en Chimie Organique. XIV. La quaternation des Amines Tertiaires par les Anhydrides Phtaliques
Authors: Mukana D. , Nagy J. B. , Nagy O. B. , Bruylants A. 
Published: September 2010

AbstractThe quaternisation of tertiary amines (triethylamine, pyridine and 1, 4‐diaza‐[2, 2, 2] bicyclooctane) by cyclic anhydrides (phthalic, 4‐nitro, 3‐nitro‐, 3, 5‐dinitro, 3, 6‐dichloro‐and tetrachlorophthalic, naphthalic anhydride) is studied in aprotic media. It appears that the reaction is strongly dependent on substituent and solvent effects. In every case a charge‐transfer complex is formed between the two reactants. This complex is a real intermediate on the reaction path. The activation parameters favour the resulting complex mechanism.
Quantitative investigation of the acid‐catalysed hydrolysis of glyceryl nitrates
Authors: Rosseel M. T. , Bogaert M. G. , De Keukeleire D. 
Published: September 2010

AbstractThe hydrolysis of glyceryl trinitrate, glyceryl‐1,3‐dinitrate, glyceryl‐1,2‐dinitrate and glyceryl‐1‐mononitrate was studied in HCl 4 N, 3 N, 2 N and 1 N, at 37°C. Densitometry was used for the quantitative determination of the four nitrate esters on thin‐layer chromatograms. The data obtained indicate that glyceryl‐1,2‐dinitrate and glyceryl‐1‐mononitrate hydrolyse at the same rate, while the hydrolysis rate is much enhanced for glyceryl trinitrate and somewhat diminished for glyceryl‐1,3‐dinitrate. In each case there is a linear relationship between log k1 and ‐Ho.
A statistical dipolar method for the determination of the structure of complexes in solution
Authors: Huyskens Pierre L. 
Published: September 2010

AbstractWhen several structures are possible for an ab complex in solution, the most probable of them can be found using a statistical dipolar method. For a given structure it is possible to calculate from the experimental values of the dipole moment of the complex μab and of the separate molecules μa and μb a value of the dipole increment Δμ resulting from the formation of the complex. The most probable structure is that one where in a given family of complexes, whose structure must be similar, one obtains the most coherent evolution of the calculated dipole increment with characteristics of the complexes, like the complexation enthalpy, or of the partners, like their pKa. In this work the theory is derived on the basis of the Fröhlich equation. It is applied to the case of the complexes between phenols and pyridines.
Oxidation products of hop bitter acids. Part IX. Six‐membered ring products from the oxidation of colupulone
Authors: van Den Bossche R. , Anteunis M. , Verzele M. 
Published: September 2010

AbstractAir oxidation of colupulone in iso‐octane solution produces a comples mixture, separation of which by Counter‐Current‐Distribution with the two phase system iso‐octane/buffer pH : 7.00 gives four 1,2‐dioxolane peroxides (III, IV, V and VI of figure 1).
Trans‐2‐isopropyl‐1,3‐dithiane‐l‐oxide; a conformationally fixed isopropylgroup
Authors: Anteunis M. , van Acker L. , Danneels D. 
Published: September 2010

AbstractIt is found by 1H n. m. r. spectroscopy that in trans‐2‐isopropyl‐1,3‐dithiane‐1‐oxide an S‐O : C‐Me synaxial type of interaction is relatively disfavoured, having its impact in the rotameric behaviour of the isopropylgroup.
Three new classes of configurationally stable organotin compounds
Authors: Gielen M. , Simon S. , Tondeur Y. , van De Steen M. , Hoogzand C. 
Published: September 2010

AbstractMethylneophylphenyltin hydride (I), (methylneophylphenylstannyl) cyclopentadienyl molybdenum tricarbonyl(II) and dimethylphenylstannylmethyl‐α‐naphthyl‐phenylgermanium (III) are configurationally stable within the NMR time scale, even in the presence of strong nucleophiles.
An intrinsic non‐equivalence in organotin chemistry
Authors: Gielen M. , Close V. , De Poorter B. 
Published: September 2010

Abstractα‐Methoxybenzyltribenzyltin shows anisochronous diastereotopic methylene protons. This intrinsic chemical shift nonequivalence is equal to 0.066 ppm.α‐Methoxybenzyldimethylphenyltin does not show anisochronous methyl protons even at 270 MHz.
Studies in organic mass spectrometry. XIX The fragmentation of the trimethylsilyl derivatives of some 2,3‐dialkyl‐1,4‐cyclopentanediols
Authors: Maenhaut‐Claeys M. , Vandewalle M. 
Published: September 2010

AbstractThe mass spectra of the TMS‐ethers of the isomeric 2,3‐dialkyl‐1,4‐cyclopentanediols are discussed. These compounds exhibit fragmentations, characteristic for the TMS‐1,3‐cyclopentanediol‐system. The dimethyl substituted compounds display differences in the ion abundances for a number of ions, depending upon the stereochemistry of the trimethylsiloxy groups, while for longer alkyl groups only differences in the intensity of a rearrangement ion at m/e 147 are found. A considerable change in the mass spectral behaviour is found for the compounds with an 1′, 2′‐unsaturated alkyl substituent.
NMR experiments on acetals. part 54. Rotameric behaviour of geminal 4‐, and 5‐phenylgroups in 1,3‐dioxanes
Authors: Bernaert E. , Anteunis M. , Tavernier D. 
Published: September 2010

AbstractThe 1H‐NMR spectra were studied of a series of 2‐Me‐5‐R‐5‐ø1,3‐dioxanes (5) (R = H, Me, Et, i.Pr; ø of 2‐Me‐spiro(1,3‐dioxane‐5,9′‐fluorene) (14), of 5‐R‐4,4‐diø‐1,3‐dioxanes (14) (R = Me, Et, n.Pr, i.Pr and i.Bu) and of 5‐R‐spiro(1,3‐dioxane‐4,2′‐adamantane) (7) (R = Me, Et, n.Pr, i.Pr, ø). From a comparative shift study, the preferential orientation of the phenylgroups in the ø‐substituted 1,3‐dioxanes were ascertained. In (10) and (10) the 5‐ø‐axial groups are bisectional (14). The 5‐ø‐equatorial groups are bisectional in the 5‐R‐5‐ø‐derivatives with R = H and Me, but flatsided with the larger substituents R = Et, i.Pr, ø. (See Chart I). For the 4,4‐diø‐derivatives, both aromatic rings are flatsided (10). In order to reach this conclusion comparison between (10) and (14), where the 5‐R‐groups occupy the axial positions, was essential. A rational explanation for the behaviour of the non‐spherical phenyl groups is offered.
Comparative Study of Various Equations for the Determination of Dipole Moments of Complexes
Authors: Pauwels Herman , Huyskens Pierre 
Published: September 2010

AbstractThree equations are considered for the determination of the dipole moment μ of complexes, derived respectively from the theory of Onsager and from that of Fröhlich and differing with respect to the role of the internal refractive indexes. In each case either no correction is made for the atomic polarization or this is put equal to 15% of the molar refraction corresponding to the Na D line. The equations are tested for some sixty complexes between compounds with a carbonyl group and phenols. Systematic differences appear between the values of μ computed by means of the three equations which are of the order of 2 a 3 Z. Taking into account the atomic polarization lowers the values of μ of some 5%. Differences in the shape of complexes belonging to the same family seem not to affect the computed values of μab, to a greater extent than the systematic errors.
Influence D'Une Faible Déformation sur le Spectre Vibrationnel de “Perovskites” Complexes A2IIBIIBVIO6
Authors: Liegeois‐Duyckaerts M. 
Published: September 2010

AbstractComplex ordered perovskites A2BIIBVIO6 are ideally cubic, but the structure may be more or less distorted by the presence of large BII cations. A comparison between the vibrational spectra of cubic and slightly distorted perovskites show that the IR spectrum remains insensitive to small deformations of the structure. However, such deformations have a non‐negligible influence on the Raman spectrum, the most evident feature being a broadening or a splitting of the band corresponding to the T2g bending mode of the BVIO6 octahedron.
NMR Experiments on Acetals. Part 55. Conformational Equilibria in 5‐Ethenyl‐, 5‐Ethynyl‐ and 5‐Cyclopropyl‐ 1,3‐Dioxane
Authors: Anteunis M. , Camerlynck R. , De Waele R. 
Published: September 2010

AbstractQuantitative conformational data are reported for the title compounds (Table I), as obtained from an extensive 1H‐NMR study at several temperatures. Identification of the Me‐5 signals (axial or equatorial) at T < TC could be achieved by spectral comparison with the corresponding anancomerized 2‐Me‐derivatives. The latter were finally related by chemical means to either r‐2‐Me‐cis‐5‐Me‐5‐Et‐1,3‐dioxane or r‐2‐Me‐trans‐5‐Me‐5‐Et‐1,3‐dioxane. The configurations of the latter two compounds were ascertained by specific long range study, established by nmdr.The conformational results show that in typical apolar solvents the unsaturated substituents slightly prefer the equatorial position with respect to Me, but the axial position in freon‐21. This may be the result of counteracting electrostatic (or dipolar) and steric contributions, but special solvent effects of undisclosed nature govern the conformational picture.
NMR Experiments on Acetals. Part 53. On the Origin of the Low Barrier to Ring Topomerization in DI i. Propyl‐1,3‐Dioxane
Authors: Tavernier D. , Anteunis M. , Bernaert E. 
Published: September 2010

AbstractThe free energy barrier to ring reversal in 5,5‐dii. Pr‐, and 5,5‐dic. Pe‐1,3‐dioxane is measured to be 7.3 (153 K) and 6.6 (137 K) kcal/mole, respectively. An explanation for this exceptionally low barrier is offered; it invokes the existence of rotamers having a carbon atom situated above the 1,3‐dioxane ring and situated along the most favoured reaction path for ring reversal. The explanation is consistent with and predicts the “normal” barriers on the contrary found for 5,5‐dic. Pr‐,4,4‐dii. Pr‐, and 5,5‐diMe‐2,2‐dii. Pr‐1,3‐dioxane. Experimental barriers to ring reversal of some model spiro compounds and of 4,4‐, and 5,5‐diø‐1,3‐dioxanes (9.5 and 10.7 kcal/mole at 172 and 221 K respectively) are reported.
Organometallic Compounds. 42. Organotin Chelates, Synthesis, Spectroscopic Properties and Stereochemical Won Rigidity
Authors: Gielen M. , Topart J. 
Published: September 2010

AbstractDi‐and triorganotin acetylacetonates and dipivaloylraethanates, and the adducts of some diorganotindihalides with bipyridyl and ortho‐phenanthroline have been synthesized. Their spectroscopic properties (MS, IR, NMR, Mössbauer) are described and discussed. In the light of NMR and literature results, one may conclude that organotin‐β‐diketonates are stereochemically non rigid.
German I ‐ Étude De La Décomposition En Phase Liquide De L'hydroperoxy‐2 Méthyl‐2 Proprionate De T. Butyle
Authors: Rafii Par E. , Lena L. , Metzger J. 
Published: September 2010

AbstractL'étude de la décomposition thermique de l'hydroperoxy‐2 méthyl‐2 propionate de t.butyle 1 (0,1 à 0,5 mole.1−1), à différentes températures dans cinq solvants, a été envisagée. La faible énergie d'activation de la réaction de décomposition de l'hydroperoxyde 1 dans les solvants polaires (22 à 24 kcal. mole−1 respectivement dans le nitrométhane et le t.butanol) permet d'envisager que, dans ces solvants, la décomposition est induite par les radicaux dérives de l'hydroperoxyde.Par contre, l'hydroperoxyde‐1 est très stable dans le benzène à une température inférieure à 100° C. Ce qui nous a permis d'envisager l'étude de sa décomposition radicalairement induite par les initiateurs dans ce solvant, Les résultats obtenus montrent que la rupture de la liaison (ROO‐H) par attaque d'un radical alkyle ou aleoxy est négligeagle vis‐à‐vis de la rupture de la liaison (RO‐OH).
Some Carbene Reactions on Myrcene
Authors: De Smet A. , Anteunis M. , Tavernier D. 
Published: September 2010

AbstractWe have ascertained the structure of the adducts of myrcene and the following carbenes: (i) dichlorocarbene (ii) carbethoxycarbene and (iii) methylene (Simmons‐Smith procedure). With dichlorocarbene, the diadduct (2', 2'‐dichloro‐3 ', 3'‐dimethyl)‐(1”‐ethenyl‐2”,2”‐dichloro)‐1, 2‐dicyclopropylethane is obtained in 42% yield. With carbethoxycarbene a mixture of two monoadducts is isolated: l‐ethenyl‐2‐(3'‐isohexenyl)‐carbethoxycyclopropane and 2‐(1'‐methylideen‐4'‐isoheptenyl)‐carbethoxycyclopropane. Both the cis‐and the trans‐isomers of these products are formed. Their configurational assignment was established by 1H‐NMR spectroscopy. By the Simmons‐Smith reaction a complex mixture of myrcene‐related compounds is obtained, containing one, two or three cyclopropane rings.
The Anodic Behaviour of Lead in Acid Sulphate Solutions. Influence of Manganese Ions and Electrochemical Oxidation of Manganese Ions at Lead Anodes
Authors: Ravindran Kanechamkandy , Heerman L. , van Simaeys L. 
Published: September 2010

AbstractResults concerning the influence of manganous ions, either singly or in combination with cobalt ions, on the anodic corrosion of lead in acid sulphate solutions are reported. The corrosion of lead is much less when it is compared to media containing only copper and cobalt ions. This fact has been corroborated by results obtained by the potentiokinetic method. Some results on the electrochemical oxidation of manganous ions at lead anodes in presence of cobalt ions are also described.
Ion‐Association Extraction Combined With Low Temperature Ashing for the Determination of Cadmium in Foodstuffs
Authors: Dewit A. , Duwijn R. , Smeyers‐Verbeke J. , Massart D. L. 
Published: September 2010

AbstractA method for the determination of Cd by AAS in foodstuffs is presented. The determination is carried out after low temperature ashing and extraction with a high molecular weight amine.Of the several extractions investigated, Aliquat 336 3% and Alamine 336 3% in Methylisobutylketone allowed the best results. The former was chosen. The analysis of international standards shows that the method yields accurate results.
General Theoretical Study of the Stepwise Coupling Methods
Authors: Alix Alain J. P. , van Der Veken Benjamin J. 
Published: September 2010

AbstractIn this second part, the authors study the convergence of the iterative procedures based on the stepwise coupling methods in the second order case: especially the Eigenvector Method of H. J. BECHER and R. MATTES and the Matrix Polynomial Expansion Method of A. ALIX. It is shown that under some simple conditions on the number m0 of iterative cycles and on the function which defines the stepwise introduction of the kinematic coupling, that the limit obtained is unique. The expression of that limit and its properties are discussed in detail.
A Self‐Consistent Field Molecular Orbital Theory With “Intermediate Neglect of Differential Overlap”, Based on the Atomic Valence State Concept
Authors: Figeys H. P. , Geerlings P. , van Alsenoy C. 
Published: September 2010

AbstractSummary. A new INDO method is developped, in which the semi‐empirical evaluation of one‐center integrals is based upon the energy expression of an atom in a valence state, according to Slater, Mulliken, Hinze and Jaffé. The values of these integrals for the first and second row elements are reported. The diatomic bonding parameters were calibrated against experimental molecular valence electronic energies (VEE). The computed VEE‐values for a series of various aliphatic and unsaturated molecules are in fair agreement with experiment.