Preparation et proprietes physico-chimiques de l'hydrure d'aluminium AlH3γ

Résumé AlH₃ a été synthétisé. La décomposition thermique de cet hydrure ainsi que la désolvatation de Al(AlH₄)₃, (C₂H₅)₂O ont été étudiés par analyse thermogravimétrique. L'analyse thermique différentielle effectuée sur AlH₃ montre un effet exothermique dû au passage à la forme AlH₃ puis endothermique correspondant à la décomposition de la phase formée. Une structure type alanate est proposée pour AlH₃ .

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Aluminium hydride has been synthetised. Thermogravimetry has been used to investigate the thermal decomposition of this phase and the desolvation of A1(AlH₄)₃· (C₂H₅)₂O. Differential thermal analysis of-AlH₃ shows an exothermic effect due to transformation to -A1H₃, followed by the endotherm of -AlH₃ decomposition. A structure of alanate type is proposed for -AlH₃.

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Zusammenfassung -AlH₃ wurde synthetisiert. Die thermische Zersetzung dieses Hydrids sowie die Desolvatation von Al(AlH₄)₃·(C₂H₅)₂O wurden mittels Thermogravimetrie untersucht. Die Differentialthermoanalyse von-AlH₃ zeigt einen dem Übergang in die AlH₃ -Form entsprechenden exothermen und mit nachfolgenden endothermen Effekt, welcher der Zersetzung der gebildeten Phase entspricht. Eine Struktur von solvatfreien Alanat-Typ wird für-AlH₃ vorgeschlagen.

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- . l(l₄)₃. (C₂H₅)₂O . l₃ , l₃. lH₃ .

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Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le Laboratoire de Chimie Minérale avec la Direction des Recherches et Moyen d'Essai. Nous remercions bien vivement cet organisme ainsi que le Centre de Recherches ELF ERAP de Solaize de l'aide qu'ils nous ont apportée.     

Preparation-Proprietes physico-chimiques enthalpie de formation de l'hydrure d'aluminium AlH3α′

Résumé L'hydrure d'aluminium AlH₃- a été obtenu par action de LiAlH₄ sur AlCl₃ ou ZnCl₂ dans l'éther éthylique. La décomposition thermique a été étudiée par thermogravimé trie sous pression réduite (10^–2 torr). La capacité calorifique molaire à 298 K, l'enthalpie de décomposition, ainsi que l'enthalpie de formation ont été déterminées avec un microcalorimètre Calvet.

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Aluminium hydride,-AlH₃, was prepared by reaction of LiAlH₄ on A1C1₃ or ZnCl₂ in diethyl ether. Thermogravimetry was used to investigate its thermal decomposition under low pressure (10^–2 torr). The molar heat capacity at 298 K, the heat of decomposition, and the heat of formation, were measured with a Calvet microcalorimeter.

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Zusammenfassung Aluminiumhydrid AlH₃- wurde durch Einwirkung von LiAlH₄ auf AlCl₃ oder ZnCl₂ in DiÄthylether hergestellt. Die Thermo gravimetrie wurde zur Untersuchung der thermischen Zersetzung bei niedrigem Druck (10^–2 torr) herangezogen. Die molare WÄrmekapazitÄt bei 298 K, die Zersetzungsenthalpie sowie die Bildungsenthalpie wurden mit einem Calvet-Mikrokalorimeter bestimmt.

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— - l₃ LiAlH₄ ll₃ ZnCl₂ . (10^–2 ) . 298 , .

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Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le laboratoire de Thermochimie Minérale avec la Direction des Recherches et Moyen d'Essai. Nous remercions bien vivement cet organisme de l'aide qu'il nous a apportée.     

Preparation et proprietes physico-chimiques de l'alanate de magnesium Mg(AlH4)2

Résumé L'alanate de magnésium Mg(AlH₄)₂ désolvaté a été obtenu avec une pureté satisfaisante. La décomposition thermique a été étudiée par thermogravimétrie sous pression réduite (10^–3 torr). La capacité calorifique molaire à 298 K ainsi que l'enthalpie de formation ont été déterminées avec un microcalorimètre Calvet.C _p Mg(AlH₄)₂=32.5 cal·mol^–1·K^–1;H _fMg(AlH₄)₂=–19.2 kcal· mol^–1

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Solvent-free Mg(AlH₄)₂ has been prepared with good purity. Thermogravimetry has been used to investigate the thermal decomposition of Mg(AlH₄)₂ under low pressure (10^–3 torr). The molar heat capacity at 298 K and the heat of formation have been measured with a CALVET microcalorimeter.C _p Mg(AlH₄)₂=32.5 cal·mol^–1·K^–1 H _fMg(AlH₄)₂=–19.2 kcal·mol^–1

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Zusammenfassung Lösungsmittelfreies Mg(AlH₄)₂ wurde mit befriedigender Reinheit hergestellt. Scine thermische Zersetzung wurde durch Thermogravimetrie bei niedrigem Druck (10^–3 torr) untersucht. Die molare Wärmekapazität bei 298 K und die Bildungswärme wurden mit einem Calvet Mikrokalorimeter gemessen.C _p Mg(AlH₄)₂=32.5 cal·mol^–1·K^–1;H _f Mg(AlH₄)₂=–19.2 kcal· mol^–1

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Mg(AlH₄)₂, . Mg(AlH₄)₂ (10^–3 ) . 298 . C_pMg(AlH₄)₂=32.5 ^–1. ^–1 H _fMg(AlH₄)₂=–19.2 ^–1.

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Ce travail a été effectué dans le cadre d'un contrat de recherches passé par le Laboratoire de Chimie Minérale avec la Direction des Recherches et Moyens d'Essai. Nous remercions bien vivement cet organisme de l'aide qu'il a nous apportée.     

Polythioamides aliphatiques—III. Etude de quelques proprietes physicochimiques

Aliphatic polythioamides are highly crystalline condensation polymers. Determinations of their solubility parameters and of the cohesive energy of the thioamide group demonstrate dipole-dipole interactions between functional groups. We have also determined molecular weights by end-group measurements using u.v.-visible spectrometry, thus allowing calculation of the coefficients of the Mark-Houwink and Stockmayer-Fixman equations.     

Etude dilatometrique de l'anisotropie d'une tole a base d'aluminium obtenue par solidification rapide

Dilatometric study of the anisotropy of an aluminium alloy sheet obtained by rapid solidification. An Al-1.99%Mn-0.80%Mg-0.60%Cr-0.40%Zr-0.13%Fe-0.05%Ti alloy produced by the twin roller melt spinning technique was characterized in terms of thermal stability at low temperature in the range 80–300K. Differences in thermal expansion coefficients in the three directions were evidenced, and revealed the presence of an anisotropy. The differences are mainly due to the nature of the intermetallic phases present in the aluminium matrix. It is important to note the low thermal expansion coefficient obtained along the direction normal to the rolling plane, as compared to those of aluminium alloys prepared by conventional methods.     

Etude des spectres vibrationnels et des proprietes physico-chimiques du cyclotriphosphate mixte de nickel et de sodium hexahydrate,NiNa4(P3O9)2.6H2O

A study of the vibrational spectra and physico-chemical properties of nickel and sodium cyclotriphosphate hexahydrate, NiNa₄(P₃O₉)₂.6H₂O. We have studied the dehydration and the calcination under atmospheric pressure of cyclotriphosphate hexahydrate of nickel and sodium, NiNa₄(P₃O₉)₂.6H₂O, between 25 and 700°C by infrared spectrometry, X-ray diffraction, TGA and DTA thermal analyses. This study allows the identification and the crystallographic characterization of a new phase, NiNa₄(PO₃)₆, obtained between 350 and 450°C. NiNa₄(PO₃)₆ crystallizes in the triclinic system, P₋₁, with the following unit cell parameters a = 6.157(3)Å, b = 6.820(6)Å, c = 10.918(6)Å, α = 80.21(5)°, β= 97.80(9)°, γ = 113.49(3)°, V = 409.8 ų, Z = 1, M(19) = 25 and F(19) = 48 (0.0095; 42). The calcination of NiNa₄(PO₃)₆, between 500 and 600°C, leads to a mixture of long-chain polyphosphates NiNa(PO₃)₃ and NaPO₃. The kinetic characteristics of the dehydration of NiNa₄(P₃O₉)₂.6H₂O were determined and discussed. The vibrational spectrum of the title compound, NiNa₄(P₃O₉)₂.6H₂O, was interpreted in the domain of the stretching vibrations of the P₃O₉ rings, on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P₃O₉ ring with D_3h symmetry.     

Etude theorique des proprietes thermodynamiques du radical CN et de ses dimeres

Using the ab initio LCAO—SCF—MO method and the 6–31G extended basis set, the CN radical and its possible dimers (NCCN, CNNC or CNCN) have been studied in terms of nuclear equilibrium geometries, normal modes of vibration, IR spectrum and thermodynamic properties. The results show that quantum chemical calculations enable these parameters to be obtained with adequate accuracy. Working properly, one can build a local potential energy surface on which to perform a harmonic vibrational analysis. Hence all the required information to apply the principles of statistical thermodynamical analysis is available.     

Etude de l'influence de la bentonite et de l'eau sur les proprietes thermophysiques et le pouvoir gazeifiant d'un moule a vert

Investigation of the effects of bentonite and water on the thermophysical properties and gasifying power of a moist mould. The quality of moulded products is related to that of the mould because the latter is the source of many defects such as porosity, blowholes, etc.… The formation of gaseous defects in the moulded products is generated by gas penetration into the parts and this happens during the formation of the first crust of solidified metal. Thus, the problem of defects due to gas penetration must be addressed in order to suppress the responsible factors. Our investigation aimed at determining the influence of bentonite and water on the thermophysical properties (such as thermal conductivity, effusivity, specific heat and diffusivity) and the gasifying power of a green moulding sand in order to obtain a good moulded product. The consequence of our results is to propose a new mixture.     

Spectres RMN de 27Al d'hydrures d'aluminium

The ²⁷Al n.m.r. spectra of LiAlH₄, AlH₃ and LiAlH(YR)₃ (Y = O or S and R = Me or t-Bu) were recorded. The parameters obtained (δAl, J(Al? H), linewidths at half-height) are discussed.     

Etude de l'acylation de l'acétyl-3 acétoxy-8 indolizine par action de chlorures d'acide en présence de chlorure d'aluminium

Study of acylation of 3-acetyl-8-acetoxyindolizine by miscellaneous acid chlorides in the presence of aluminium chloride shows that this reaction is either limited to a transesterification (in the case of benzoyl chloride) or leads to introduction of an acyl group in position 1 with simultaneous liberation of the phenol function in position 8. When acylation takes place, acetyl chloride resulting from the cleavage of the acetoxy group competes with the acid chloride used in the reaction. Predominant acylation by the latter is observed when the reaction is performed with ethoxalyl chloride or with non branched aliphatic acid chlorides; by contrast solely acetylation takes place when pivaloyl or phenylacetyl chloride is used. These results are tentatively explained by a process related to the Fries rearrangement. The hypothesis of intramolecular transfer of an acyl group from the ester function in position 8 can be discarded by the observed results.     

Etude par desorption thermique programmee des proprietes des argiles modifiees

The present work tries to emphasize the effect of acid/basis properties of montmorillonite type clays by ion exchange with cations of different natures. The acidity and basicity measuring was made by thermo programated desorption (TPD)1,2, using ammonia like basis agent and carbon dioxide like acid agent. With TPD method we can determine acid/basis proprietes by measuring of the quantity of the ammonia and carbon dioxide termodesorbed. Clays are crystalline aluminosilicates, similar with the zeolyts, who presents the property of ion exchanging. That propriety can be applicated for pollutants cations from aquatic solutions. Ion exchanging propriety depends of a lot of factors: the cation nature, the valence and the ionic ray of the cation present in the impregnated solution. That's an advantage for depollution process of heavy metals by fixing of these metals by montmorillonite structure. By using TPD metod we can obtaine a caracteristic diagram. This revised version was published online in July 2006 with corrections to the Cover Date.     

Etude par effusiometrie de torsion des proprietes thermodynamiques en phase solide des laitons binaries (Cu,Zn)

The Gibbs thermodynamic variables which we have determined for thirteen brass alloys (Cu, Zn) are in good accord with the literature. The experimental conditions were as close as possible to those of sublimation in static vacuum. The application of the test of the third law in β-brass shows that our free enthalphy measurements are in agreement with the measurements of specific heat by Moser. The primary solid solution α copper of the binary brasses shows quasi-regular behaviour over the whole composition range. Our measurements seem to indicate the existence of a β′/(α + γ) eutectoïd at a temperature less than 100°C. The high degree of order of the γ phase is seen in the large negative values of excess entropy.     

Preparation et proprietes de quelques sulfures de phospholes fonctionnels

^tBuLi with 1-phenyl 3,4-dimethyl phosphole sulfide 1 in THF, gives a mesomeric anion 4. With aldehydes and ketones, this anion leads to methyl-substituted phospholes (6 and 9), 2-substituted phospholes (8) or 2-substituted 3-methylene phosphol 4-enes (5 and 7). With CO₂ and CH₃COOEt a 2-phosphole carboxylic acid 11 and a 2-acetyl phosphole 10 are obtained, respectively. The spectra of the 2-substituted phospholes are studied in some detail. Some of their chemical properties (dimerization, dissociation and tert-butylation) are also described.     

Etude de la corrosion du nickel et du cuivre par le dioxyde de soufre pur ou en presence d'oxygene au moyen des proprietes electriques

Electrical measurements of corrosion scales growing on copper and nickel in SO₂O₂ atmospheres show a different behaviour for both metals. For copper, the electrical conductivity indicates that Cu₂S is formed in pure SO₂ and Cu₂O in SO₂O₂ mixtures (ratio P_SO2/P_O2 = 10⁵). In the case of nickel, the high conductivity of product scales in atmospheres containing pure SO₂ or SO₂O₂ is consistent with an interconnected Ni₃S₂ phase in NiO. In all cases the corrosion scales have a positive Seebeck coefficient.     

Reticulation et proprietes mecaniques de polyesteramides insatures

A two-step process during the cross-linking of unsaturated polyesteramides is revealed by differential thermal analysis. The first step involves copolymerization of fumaric double bonds with styrene; the second is homopolymerization of part of the residual fumaric double bonds. Study of the mechanical properties of cross-linked polyesteramides shows that the properties of a cross-linked polyester are improved by the addition of a long chain aliphatic amino-acid.     

Synthese et proprietes ionophores de macrocycles tetrapyrazoliques

The synthesis of a tetraaza-porphyrinogen tetra-substituted by dimelhylamino groups (electrodonor groups) has shown the influence of those substitutions above the ionophoretic properties of this macrocycle. The complexation of alkali, ammonium and calcium cations by these compounds has been studied by the extraction method. In all cases, the complexing ability of the substituted compound is higher than its unsubstituted homologue. This effect is less pronounced for the transport of the same cations across a liquid membrane.     

Etude structurale de l'heptafluorouranate de nitrosyle

A structural study of NOUF₇ complex is presented. An interpretation of X-ray and neutron diffraction data has been drawn from comparison with those obtained for NOUF₆ complex. An NMR study on fluorine has shown different atomic motions in the complex fluoride.     

Dosage de traces de zirconium dans les materiaux a la base d'aluminium par spectrographie

Sans résumé

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Determination of Traces of Zirconium in Aluminium Based Material Bestimmung von Zirkoniumspuren in Al-haltigen Materialien

     

Etude Structurale de Cations-Radicaux

Mass analysed ion kinetic energy spectrometry has been used to study the structure of radical cations from 26 precursor molecules. Metastable ion characteristics, viz. kinetic energy releases, abundance ratios, and isotope distribution in labelled compounds, show that all the metastable ions are isomerized into a common structure or similar mixture of structures before fragmentation. Collision induced dissociations and collisional ionization to doubly charged ions have been used to study stable ions whose lifetimes are greater than the time-of-flight from the source to the collector, and the results are interpreted on the basis of the occurrence of mixtures of initial and isomerized species.