Application de la thermogravimetrie,de l'analyse thermique differentielle et de la spectrographie d'absorption infrarouge a l'etude de la reaction entre l'oxyde de chrome(III) et les nitrates alcalins

Résumé On dose, à l'état solide, des mélanges chromate-bichromate de potassium, à côté d'oxyde de chrome(III), par spectrophotométrie d'absorption infrarouge et par analyse thermique différentielle. Certains aspects de la dissociation du bichromate de potassium ont été mis en évidence.

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Mixtures of chromate and dichromate were determined in the presence of chromium(III) by infrared spectroscopy and differential thermal analysis. Questions connected with the dissociation of potassium dichromate were also treated.

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Zusammenfassung Es wurde über die Bestimmung von Chromat-Bichromat Gemischen in fester Phase durch infrarote Spektroskopie und Differentialthermoanalyse in Gegenwart von Chrom(III) berichtet. Fragen der Dissoziation von Kaliumbichromat wurden ebenfalls erörtert.

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() (III). .

     

Etude de la structure de l'iodatochromate de potassium par spectrographie d'absorption infrarouge entre 3 et 35μ

Résumé Dans le spectre d'absorption infrarouge de l'iodatochromate de potassium K[(CrO₃)(IO₃)], on peut identifier la présence de bandes de vibration de valence de ponts Cr-0-I à 508 et680 cm^–1.

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Summary The infrared absorption spectrum of potassium iodatochromate K(CrO₃)(IO₃) contains vibration bands of the valence bridges Cr-O-I at 508 and 680 cm^–1.

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Zusammenfassung Im Infrarot-Absorptionsspektrum des Kaliumjodatochromats lassen sich Banden der Valenzschwingungen der Atomgruppe Or-O-J bei 508 und 680 cm^–1 nachweisen.

     

Apport de l'analyse thermique differentielle quantitative a l'etude du polymorphisme du nitrate de potassium a la pression atmospherique

Résumé Application de l'ATD quantitative à l'étude des transformations structurales du nitrate de potassium. Les échantillons (1 à 8 mg) sont chauffés et refroidis dans l'azote sec, à la pression atmosphérique. Au refroidissement, on observe toujours les transitions successives I III II. Le pic exothermique correspondant à I III apparaît dans un intervalle de température très reproductible (118 – 120°). Les mesures de surface confirment la parfaite réversibilité de I III déjà signalée par C. Mazières. Les transitions III I et II I ont lieu pratiquement à la même température (127–130°) mais l'aire du pic endothermique correspondant à III I est plus faible et représente 51.5 % de la valeur observée pour II I. En prenantH=13.2 cal/g comme valeur de référence pour la transition II I, on trouveH=6.8± 0.2 cal/g pour III I. La transformation III II suit un processus en deux étapes, fortement influencé par le traitement thermique antérieur de la phase I.

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The changes in the structure of potassium nitrate have been studied by differential thermal analysis. The samples were heated and cooled in a stream of dry nitrogen, at atmospheric pressure. On cooling, the following transformations have been observed: I III II. The exothermic peak corresponding to the I III transformation appeared at 118–120° with good reproducibility. Surface area measurements show the complete reversibility already observed by Mazières for the I III transformation. The III I and the II I processes take place at the same temperature (127–130°), but the peak corresponding to the III I change is of lower intensity, representing only 51.5% of that of the peak belonging to the II I transition. If the enthalpy change belonging to process II I,H=13.2 cal/g, that belonging to transition III I,H=6.8±0.2 cal/g. Transformation III II proceeds in two steps and is greatly influenced by the preceding heat treatment of phase I.

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Zusammenfassung Quantitative Differentialthermoanalyse wurde zur Untersuchung der strukturellen Umwandlungen von Kaliumnitrat herangezogen. Die Proben (1–8 mg) wurden in trockenem Stickstoff bei atmosphärischem Druck erhitzt und abgekühlt. Beim Abkühlen lassen sich immer die sukzessiven Umwandlungen I III II beobachten. Die dem Übergang I III entsprechende exothermische Spitze erscheint sehr reproduzierbar bei 118–120°. Die Oberflächenmessungen bezeugen die vollständige Reversibilität von I III, schon früher angegeben von Mazières. Die Übergänge III I und II I erfolgen praktisch bei gleicher Temperatur (127–130°), doch die endothermische Spitze von III I ist schwächer und entspricht nur 51.5% des für II I beobachteten Wertes.H=13.2 cal/g als Referenzwert für Übergang II I genommen, ergibt sichH=6.8±0.2 cal/g für III I. III II Übergang verläuft in zwei Schritten, die durch das thermische Vorleben der Phase I stark beeinflußt sind.

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. . I III II. , I III, 118–120°. , I III. III I II I (127–130°), , III I 51,5% III. II I H=13,2 /. III I 6,8 ± 0,2 /. III II I.

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Mémoire présenté en l'honneur du 70^e anniversaire du Professeur Clément Duval.     

Etude par thermogravimetrie,analyse thermique differentielle et spectrographie d'absorption infra-rouge de la reaction du peroxyde de sodium sur l'oxyde de Beryllium

Thermogravimetric and differential thermal methods as well as chemical analysis show that sodium peroxide attacks beryllium oxide to form beryllate, apparently in the molecular ratio 1 Na₂O:1 BeO. An unidentified peroxy compound of beryllium is formed at about 165° by the action of the NaO² present in the Na₂O₂ sample; it decomposes between 280 and 310°. IR absorption spectroscopy indicates the presence of Be-O bonds in the sodium beryllate which are different from those in the oxide used.     

Sur les spectres d'absorption infrarouge,entre 2,5 et 16 μ, de semicarbazones

The spectra of 120 semicarbazones in the solide state have been studied between 2.5 and 16 microns in order to correlate absorptions and structures. We have considered most particularly the absorptions v(N-H) and the so-called amid-I and amid-II bands.     

Contribution de l'analyse thermique a l'etude des acides humiques et de leurs sels de sodium

Résumé On a étudié le comportement thermique sous oxygène des acides humiques et de leurs sels de sodium. On prépare les humates de sodium, soit par neutralisation des acides humiques, soit par dialyse de leurs pseudo-solutions dans la soude. L'examen des spectres infrarouges et de diffraction X des prélèvements effectués entre les étapes de dissociation (suivie par ATD-TG -TGD) suggère un double mécanisme. Au-dessous de 500°, il s'est formé du carbonate de sodium et du carbone. Dès 600°, débute la dissociation du carbonate. Le carbone restant s'oxyde brutalement à 770°. L'importance de la réaction varie avec la teneur initiale en sodium.

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The thermal behaviour of humic acids and their sodium salts in oxygen has been studied. The sodium humates were prepared by neutralization of humic acids or by dialysis of their pseudosolutions in sodium hydroxide. Infrared and X-ray diffraction spectra of samples taken between the dissociation steps obtained from the DTA-TG-DTG curves suggest a double mechanism. Below 500°, sodium carbonate and carbon are formed. At 600°, the dissociation of carbonate starts. The residual carbon burns at once at 770°. The extent of reaction changes with the amount of sodium initially present.

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Zusammenfassung Es wird über die Untersuchung der thermischen Eigenschaften von Huminsäuren und ihren Natriumsalzen unter Sauerstoff berichtet Letztere wurden entweder durch Neutralisation der entsprechenden Huminsäuren oder durch Dialyse ihrer Pseudolösungen in Natriumhydroxyd erzeugt. Die infrarotspektroskopische und röntgenanalytische Prüfung von zwischen zwei (durch DTA, TG und DTG verfolgte) Dissoziationen entnommenen Proben zeigt zwei Vorgänge. Unter 500° werden Natriumkarbonat und Kohle gebildet. Bei 600° beginnt die Dissoziation des Karbonats. Die zurückbleibende Kohle wird bei 770° plötzlich oxidiert.

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Na- . . - , ( — ), . 500° . 600° . 770°. .

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En l'honneur du 70^e anniversaire du Professeur Clément Duval. Etude entreprise dans le cadre des travaux de l'Equipe de Recherche Associée du C. N. R. S. n 220 (Pédologie des Pays Atlantiques).     

Contribution a l'etude de la conductivite thermique de liquides et solutions

The study of a new spherically symmetrical apparatus to measure heat conductivity of particular liquids under transient heat transfer conditions is proposed. Three experimental investigations on paraffin oil, cyclohexanon, and macromolecular solution are presented.     

Etude cinetique d'une decomposition thermique par couplage de la calorimetrie et de l'analyse thermique a vitesse de decomposition constante

A method is described where the simultaneous measurement of a thermal flow (by means of Tian-Calvet type calorimetry) and of a gas flow (by means of constant decomposition rate thermal analysis) allows the knowledge at any time of the instantaneous enthalpy of thermal dissociation. The method is used to study the thermal decomposition of an industrial Al(OH)₃ gibbsite sample.     

Le developement de l'etude de la diffusion de la lumiere et des neutrons par les polymeres a strasbourg

In this paper one recalls the history of the development of scattering studies after the first world war in Strasbourg. Tremendous progress has been made and some examples of this progress are discussed     

Quelques aspects de la connaissance par l'analyse thermique,des residus d'evaporation de solutions mixtes d'hydrogenocarbonates de calcium et de magnesium

Journal of Thermal Analysis and Calorimetry - Les difficultés de l'étude des résidus d'évaporation de solutions mixtes de Ca(HCO3)2 et de Mg(HCO3)2, par les...     

Determinations cinetiques par microcalorimetrie differentielle en programmation de temperature. II. Influence de la variation de la sensibilite du calorimetre avec la temperature sur les valeurs trouvees pour les constantes de vitesse et les enthalpies de reaction

The variation with temperature of the sensitivity of a “Thermanalyse” microcalorimeter has been determined using the electrical calibration system of the apparatus. From the results, a method for the correction of the differential scanning microcalorimetric diagrams has been developed. The influence on the determination of the rate constants during kinetic studies of the decompositions of free radical initiators and on enthalpy measurements has been studied.     

Comportement thermique et etude des melanges binaires: ethinyl-estradiol — lynestrenol,ethinyl-estradiol — acetate de chlormadinone par thermomicroscopie,analyse calorimetrique differentielle et mesure de la transparence

Study of the thermal behaviour of the active ingredients and establishment of the conditions for the eventual formation of the most stable polymorphic forms permitted the phase diagrams to be obtained for ethynyl-estradiol — lynestrenol (A) and ethynyl-estradiol — chlormadinone acetate (B) mixtures by means of thermomicroscopy, differential scanning calorimetry and the transparency method. The compositions of the eutectic (for A and B) and peritectic points (B) and that of a defined compound (B) were determined from a further physicochemical study, particularly as regards solubility in relation to bioavailability.

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Zusammenfassung Eine Untersuchung des thermischen Verhaltens der aktiven Ingredienten und die Ermittlung der Bedingungen für die eventuelle Bildung der stabilsten polymorphen Formen ermöglichte, Phasendiagramme für Mischungen von Ethynyl-estradiol-Lynestrenol (A) und Ethynylestradiol-Chlormadinon-acetat (B) mittels Thermomikroskopie, DSC und der Transparenzmethode zu bestimmen. Die Zusammensetzung am eutektischen (für A und B) und peritektischen (für B) Punkt und die einer definierten Verbindung (B) wurden in Hinsicht auf eine physikalisch-chemische Untersuchung bestimmt, die sich im besonderen mit der Beziehung zwischen Löslichkeit und der therapeutischen AktivitÄt des Medikamentes (der BiodisponibilitÄt) befa\t.

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, - () (). . - , () ().

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Nous adressons nos plus vifs remerciements eu Laboratoire Cassenne qui a eu l'amabilité de nous procurer les échantillons d'ethinyl-estradiol (lot n 4 F 0353) et d'acétate de chlormadinone (lot n B 5 F 5002).Nous remercions le Laboratoire Organon qui a eu l'obligeance de nous procurer l'échantillon de lynestr6nol (lot 2/4102) par I'intermédiaire du Docteur Marie Mayer.     

Relations entre la structure electronique des films de passivation formes sur les aciers inoxydables et la susceptibilite de ces derniers a la corrosion par piqures

The passive films formed on 316L stainless steel in various NaCl solutions have been investigated by capacitance measurements (Mott-Schottky study). Pitting parameters have been determined using the galvanokinetic polarisation method. The obtained results reveal the existence of a shallow and a deep donor level localised in the band gap of the semiconducting oxide film. These energy levels are due to iron ions in the tetrahedral and octahedral positions. It also appears that the participation of the deep donor level affects the electric field. The study developed allows us to compare characteristic parameters of the electronic structure of the passive film to those related to pitting susceptibility.     

Reactivite des composes ethyleniques—XL: Bromation—influence de la temperature dans le cas de composes aryles: relations theoriques et experimentales entre les constantes de substituant,la constante polaire de reaction et les parametres d'activation

A critical re-examination of the formal aspect of the temperature effect on a chemical reaction led to a revision of certain usual concepts related to the reaction constant and the isokinetic relationship. The proposal for the possibility that non-linear relations may exist, instead of the mere linear relations usually accepted, between ΔH^≠ (and TΔS^≠) and the substituent constants lies on the hypothesis of common terms between ΔH^≠ and TΔS^≠ that cancel out in ΔG^≠. The resulting free energy relationships remain linear over a certain temperature range whatever the behaviour, isokinetic or not, of the system. These proposals are confirmed by the experimental study of styrene bromination in a methanol-sodium bromide medium at very small reactant concentrations, a reaction which is neither isokinetic nor isoenthalpic nor isoentropic. For a series of parasubstituted derivatives, the relations observed between ΔH^≠ (and TΔS^≠) and σ⁺ are hyperbolic. The results on the temperature effects in the case of styrenes and 1,1-diphenylethylenes not only support the formal study, but also reveal some ambiguities arising from a too direct interpretation of certain kinetic parameters (deuterium secondary isotope effect, ?⁺ or ΔS^≠ values) in elucidating the nature of the activated complex in the electrophilic addition step of bromination.     

Relations entre la structure et les proprietes des membranes de polytetrafluoroethylene greffe—I. Membranes monogreffees carboxyliques ou basiques

We have determined the equilibrium properties (neutralization and swelling and the transport properties: conductivity and dialysis) of hydrophilic membranes obtained by radiation grafting of acrylic acid or 4-vinylpyridine onto thin PTFE films. The presence of strong counter-ion-membrane interaction (PTFE-PAA-K⁺ and PTFE-P4VP-ClO^?₄) has been confirmed in the beginning of neutralization. The grafting ratios of the samples ranged between a few percent and several hundreds percent. The properties have been studied in connection with the average degrees of ionization and the average molalities of the reactive groups throughout the whole thickness of the membrane. The parameters of the synthesis which determine the structure of acid or basic grafted chains also have an influence on the properties of the resulting membranes. For a high dose-rate (> 100 rad min^?1), the properties of carboxylic membranes are related to the degree of cross-linking: for smaller dose rates, the properties are related to the length of the grafted branches and/or to the state of the skeleton of PTFE. For the basic membranes, the properties are controlled by the length of the grafted branches and the importance of the micro-phase-separation between PTFE and the grafted chains; for low dose rates, when the grafted branches are long, separation of hydrophobic and ionizable zones is noticed for grafting ratios higher than 5%. The carboxylic membranes with lower degrees of grafting, prepared with a high dose rate, exhibit very good permselectivity. The pyridinic membranes with a low degree of grafting could be of practical interest, viz. the manufacture of selective electrodes for perchlorate ions.     

Methode d'analyse debitmetrique appliquee a l'etude de reactions de la forme solide 1⇌solide 2+gaz,en fonction de la temperature et de la pression

Résumé Une méthode d'analyse débitmétrique à laquelle peut Être associée ATD est présentée. Elle s'applique à l'étude de réactions de la forme solide 1 solide 2+gaz dans des domaines de températures et de pressions jusqu'à 900 et 150 bar.On décrit le principe de la mesure et les conditions de fonctionnement d'un dispositif expérimental plus particulièrement mis au point pour l'étude de la décomposition thermique de CdCO₃ en atmosphère de CO₂.Cette méthode sensible et précise permet d'obtenir des résultats quantitatifs.

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An experimental device based on the measurement of gas flow rate is described, to which a DTA apparatus can be attached. The method is suited to the investigation of reactions of the type Solid₁Solid₂+gas, in the temperature interval up to 900C and at pressures up to 150 bar. The principle of the measurements is given, as well as the working conditions of an experimental device constructed specially to study the thermal decomposition of CdCO₃ in a CO₂ atmosphere.This sensitive and accurate method enables quantitative results to be obtained.

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Zusammenfassung Es wird eine Methode der Strömungsmessungs-Analyse beschrieben, an die DTA angeschlossen werden kann. Sie eignet sich zum Studium von Reaktionen des Typs: Festkörper 1 Festkörper 2 + Gas im Temperatur- und Druckbereich bis zu 900, bzw. 150 bar.Das Meßprinzip wird beschrieben, sowie die Betriebsbedingungen einer besonders zum Studium der thermischen Zersetzung von CdCO₃ in CO₂-Atmosphäre entwickelten Versuchsvorrichtung.Diese empfindliche und genaue Methode ermöglicht quantitative Ergebnisse.

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, , . = + 900 150 . , CdCO_{3 2}. , , .

     

Effets de substituant,d'hétéroatome et de solvant sur les cinétiques de décoloration thermique et les spectres d'absorption de photomérocyanines en série spiro[indoline-oxazine]

Substituent, Heteroatom, and Solvent Effects on the Thermal-Bleaching Kinetics and Absorption Spectra of Photomerocyanines Issued from Spiro[indoline-oxazines] Quantitative information useful for the development of new photochromic systems is obtained from the study of heteroatom and substituent effects on the thermal-bleaching kinetics and the absorption spectra of the photomerocyanines issued from spiro[indoline-oxazines]. The effect on photochromic properties of the presence of N-atoms either in the dimethine bridge or in the aromatic rings has been investigated through the comparison of spiro[indoline-naphthopyrans] C with spiro[indoline-naphthoxazines] A and with spiro[indoline-quinolinoxazines] B . Besides the occurrence of biexponential thermal-bleaching kinetics in non-polar solvents is observed: a tentative explanation for this observation is given which involves the formation, in either sequential or parallel steps, of energetically distinct stereoisomers of the opened form.     

Determination de la fonction d'excitation de la reaction nucleaire1H(15N, α γ)12C entre 6 et 14 MeV

Thick targets (mica) and thin hydrogen layers obtained by ionic implantation of protons in silica are used to establish the excitation function of the nuclear resonant reaction¹H (¹⁵N, α γ)¹²C. Two main resonances in the energy gap explored were observed. Their FWHM and the cross section at E_R are specified. The experimental conditions required and the performances allowed, using this reaction to determine hydrogen depth profiles in the near surface region of solids, are presented. Examples concerning borosilicates, leached in aqueous medium, are given.      

Complexes optiquement actifs de la serie du titanocene. Premiere filiation absolue entre les derives carbones et les complexes du titane a chiralite centro-metallee

Optically active titanocene complexes are synthesised starting from a fulvene asymmetric reduction. The optical purity is determined by analogy of these compounds with ferrocene derivatives.An absolute configuration is proposed for some titanium chiral complexes by reference to chiral ferrocene compounds.