Analyse des composes fluores corrosifs par chromatographie gazeuse : Controle du fluor libre

A purely chromatographie and sufficiently general method is described for the analysis of molecular fluorine in permanent inert gases or in other corrosive fluorine compounds (UF₆, HF). The method is also applied to the analysis of permanent inert gases (even in trace quantities) in the same fluorine compounds. In this method, one or several chemical “precolumns” are placed in series with a gas-liquid chromatography column. The “precolumn” system retains or destroys the corrosive compounds (UF₆, HF, F₂) and the chromatography column separates the components formed.     

Utilisation de l'ultracentrifugeuse pour la mesure des masses et pour l'etude de la polydispersite des polymeres de synthese

After a review of the two techniques based on sedimentation rate and equilibrium in binary medium, more recent methods involving the presence of a second non-macromolecular solute are described. Application of these methods to synthetic polymers is still rare but of increasing interest. The use of computers simplifies the exploitation of the measurements.     

Halogenures de zinc,cadmium et mercure (II) solvates par des amines aliphatiques. Conclusions sur la stabilite thermique et l'etude thermochimique des ces composes

The addition compounds of anhydrous zinc, cadmium and mercury (II) halides with propylamine, isopropylamine, butylamine and isobutylamine have been studied.The enthalpy variation based on the evolution of the amine molecules and the standard enthalpies of formation have been determined. An estimation method is proposed for the latter.     

Stereochimie de l'addition des derives zinciques des ethers propargyliques sur les composes carbonyles

The stereochemistry of the addition of the zinc derivative of ether PhCCCH₂OMe, to aldehydes and ketones has been studied. In the case of saturated carbonyl compounds, the results can be explained by a mechanism which takes into account the steric effects of the substituents. However, with those which contain phenyl, vinyl or alkynyl groups in the α position, conformational and electronic factors must be considered.     

Synthese et etude de l'agregation moleculaire d'amines derivees de l'adamantane

Adamantanealkanamines were prepared by a new method: the wittig reaction of aminophosphonium ylides with 2-adamantanone. Conductance measurements have been employed to examine and compare the aggregation behaviour of these compounds.     

Sur les composes chlorofluores de l'antimoine III : etude structurale de CsSbClF3

CsSbClF₃ was prepared in aqueous solution with CsCl and SbF₃. The structure was solved by means of a three dimensional Patterson synthesis. Antimony shows an unpublished coordination 8 : 5 fluorine atoms, 2 chlorine atoms and the lone pair of electrons E situated on the corners of a hendecaedron     

Influence du silicium et du germanium sur l'ene-reaction-comportement inattendu des allenylsilanes

The determining role of silicon and germanium for ene syntheses was confirmed in the reactions between 1-sila and 1-germacyclopent-3 enes or allenylsilanes and PhSO₂NSO, a highly reactive new enophile. In the case of the cyclic enes the reaction led to new α,β-unsaturated β-functional cyclic derivatives which can be easily reduced into the corresponding thiols. With allenylsilanes, the adducts resulting from the ene-reaction with PhSO₂NSO or 4-phenyl 1,2,4-triazoline 3,5-dione have an acetylene structure whereas the substituted allenes usually give conjugated diene derivatives.     

Impregnation du polyterephtalate d'ethylene glycol par des composes terephtaliques-methode statique-methode dynamique

A study was made of the sorption of various terephthalic compounds in samples of ethylene glycol polyterephthalate with various morphologies. A static and a dynamic method of impregnation were employed and compared. The dynamic method can be applied to a study of every system of two phases animated by a uniform relative movement of translation, whereas the static method is more rigorous. Only the amorphous polymer treated with solvent (dioxane) absorbs relatively large quantities of terphthalic compounds at temperatures below the vitreous transition point of the polymer. The absorbed product becomes distributed near the surface of the material, and can be fixed there by thermal treatment subsequent to impregnation. This thermo fixing causes the collapse of the swollen macromolecular structure engendered by the solvent treatment. It is thus possible to modify the surface properties of the polymer.     

Thermodynamique de composes azotes. VII. Etude thermochimique du pyrazole et de l'imidazole

Enthalpies of sublimation for pyrazole and imidazole have been obtained by calorimetry at 298.15K. The ΔH⁰_sub (298.15 K) values for these two compounds are, respectively, 69.16 ± 0.32 and 74.50 ± 0.40 kJ mole^?1. From literature data obtained by combustion calorimetry for ΔH⁰_f (c, 298.15 K), the enthalpies of formation of these compounds in the gaseous state (pyrazole: 185.1 ± 2.3 kJ mole^?, imidazole: 133.0 ± 1.7 kJ mole^?1) have been derived. Several energy values related to the molecular structure of these two compounds (as resonance energy, enthalpy of isomerization, …) have been determined. The study of pyrazole has enabled us to contribute to the evaluation of some characteristics of the NN bond.     

Activation a l'aide de polyamines tertiaires de la polymerisation anionique du styrene amorcee par les composes organolithiens

A study of the influence of tertiary polyamines on the reactivity of polystyryllithium ion-pairs in hydrocarbon solvents has been performed. The stability of active centres has been studied and allows the processing of kinetic data as for living systems. Rate constants of propagation have been measured in terms of the structure of the polyamine, its relative concentration, the concentration in organometallic species, the temperature and the nature of solvent; in all cases, they are absolute rate constants. The values show the important effect of the number of nitrogen atoms in the additive and especially the strong influence of its geometry: the cyclic polyamine studied leads to an activation of the reaction much greater than that of the corresponding linear substance. These results may be interpreted in terms of different solvation states for the polystyryllithium ion-pairs.     

Influence des substituants sur l'activite catalytique des composes arene-chrome tricarbonyle,mise en evidence de l'imfortance d'un α-heteroatome (O,N)

Substituents bearing a heteroatom in α position to an Cr(CO)₃-complexed arene group induce a strong perturbation in the six-electron ligand—metal bond allowing an increased catalytic effiency of these derivatives under mild conditions.     

Effets de complexation de l'ester lors de la catalyse par l'eau ou les sels de l'hydrolyse alcaline des esters maloniques: etude cinetique,spectroscop

When water or salts are added, catalytic effects on alkaline hydrolysis of malonic esters in methanol are observed; they are definitely greater than those observed with monoesters. Kinetic data in the presence of salts suggest that ester-M⁺ complexation phenomena is predominant and prevails over HO^-, M⁺ ionic association. Infrared and Raman spectra of esters in water-alcohol mixtures, with or without added salts, indicate the formation of 1:1 and 1:2 complexes with each carbonyl of the diester and one proton donor molecule as well as with Li⁺.Ab initio calculations of these diesters and of their complexes allow the estimation of the positive charge density at the carbonyl group carbon as well as the LUMO energy levels; they lead to an interpretation of these entities reactivities according to perturbation theory. Only orbital control of alkaline hydrolysis of esters gives an account of the relative reactivities of mono- and diesters with or without added salts. The only consideration of charges at the carbonyl carbon is, on the other hand, inadequate for justifying all the observed phenomena.     

Calcul a priori des deplacements chimiques en RMN du 19F. 1. Modele previsionnel adapte aux composes aliphatiques fluores lineaires

A new empirical model for the a priori calculation of the chemical shifts in ¹⁹F NMR spectroscopy for fluorinated linear aliphatic compounds is described. In contrast to previous models, it takes into account the influence of distant atoms (up to 5 bonds). Comparison between measured and calculated chemical shifts in linear saturated molecules containing hydrogen and halogen atoms shows a significantly increased accuracy for the present model with regard to that described previously. Perfluorinated linear saturated carboxylic acids are also studied using the model described.