Étude de la phényl-2 oxine et de ses chélates: Constantes de dissociation de la phényl-2 oxine

The authors determined, by spcctrophotometric and potentiometric methods, the ionization constants of 2-phenyl-8-quinolinol in hydroalcoholic solutions.     

Étude de la phényl-2 oxine et de ses chélates: Préparation et propr1étés de la phényl-2 oxine

The authors prepared phenyloxin by three different methods. They obtained a product whose melting point was 59° C and then another form melting at 72° C. Ultraviolet absorption spectra were determined in cyclohexan and in alcohol-watermixtures; from these determiaations, the solubilities of phenyloxin in water and in alcohol-water mixtures of different concentrations were obtained. If ultraviolet absorption spectra are plotted for different pH values (from 1.1 to 13.7) several isobestic points are noted.     

Nitration et dosage de la phénylalanine

This paper comprises a study of the conditions for nitrating phenylalanine and an investigation of the compounds obtained, polarographic and chromatographic methods being employed. At the same time some nitrobenzoic acids that are found among the nitration products of nitrophenylalanine were examined by both these methods.A method has been proposed for the polarographic determination of phenylalanine, by means of which as little as 30γ of this substance can be detected in 10 ml solution. With concentrations between 2.4.10^-4M and 6.10^-3Mt, the error is less than 2.5%, with those of the order of 2.10^-5M it approaches 12%.     

Synthèse de composés macrocycliques comportant deux fragments coordinants séparés et différents,de type bipyrldyl-2,2' et diphényl-2,9 phénanthroline-1,10.

Macrocyclic compounds containing a 2,9-diphenyl -1,10-phenanthroline subunit and a peripheral 2,2'-bipyridine chelate have been synthesized. In compound 4, the links between both coordinating fragments are flexible enough to allow complete folding of the molecule during complexation whereas in 5, the complexing moieties are rigidly held apart and cannot bind to the same metallic center.     

Sur les propriétés électroniques de la phénothiazine et de son radical

Résumé La phénothiazine et son radical sont probablement pliées le long de l'axe passant par les deux hétéroatomes centraux. Des calculs sont effectués par la méthode des orbitales moléculaires sur la modification des caractéristiques électroniques de la phénothiazine en fonction du pliage. On montre, que les densités de spin calculées pour les différentes configurations spatiales possibles du radical phénothiazinique permettent, par comparaison avec les densités expérimentales, de choisir la configuration la plus probable. C'est la configuration pliée dans laquelle le proton attaché à l'azote se trouve placé entre les deux cycles latéraux. L'étude des potentiels d'oxydation polarographique montre qu'au contraire dans les dérivés 10-substitués de la phénothiazine, le substituant aliphatique trop volumineux est placé hors des cycles latéraux.

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Phenothiazine and its free radical are probably folded along the axis passing through the two central heteroatoms. Calculations are carried out by the molecular orbital method on the modification of the electronic characteristics of the phenothiazine ring as a result of folding. It is shown, in particular, that the spin densities calculated for the different possible geometrical configurations of the phenothiazine free radical permit, by comparison with experimental spin densities, to deduce which configuration is the most probable. In the present case, this is the folded configuration in which the proton attached to the nitrogen atom is placed between the two lateral rings. The energy of the highest filled molecular orbital is also a sensitive function of the geometrical configuration of the molecule. The study of the polarographic oxidation potential of substituted phenothiazines shows that, in contrast to the parent molecule, in the N-alkyl substituted derivatives the voluminous alkyl substituent is probably pushed out to an external position with respect to the lateral rings.

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Zusammenfassung Phenothiazin und sein Radikal sind wahrscheinlich längs der N-S-Verbindungslinie geknickt. Wir berechneten nach der MO-Methode die Änderungen der elektronischen Eigenschaften des Moleküls mit dem Knickwinkel. Der Vergleich der für die verschiedenen denkbaren Konfigurationen des Radikals berechneten Spindichten mit Meßwerten erlaubt, eine von ihnen als am wahrscheinlichsten auszuwählen. Es ist die geknickte Form, in der das H-Atom am Stickstoff zwischen den aromatischen Ringen liegt. Die Untersuchung der polarographischen Oxydationspotentiale zeigt dagegen, daß in den N-alkyl-substituierten Phenothiazinderivaten die aliphatische Gruppe von den Seiten-Ringen wegsteht.

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Ce travail a bénéficié de la subvention CY-3073 du Public Health Service des Etats-Unis (National Cancer Institute).     

Structure électronique du phénol,de l'ion phénate et du phénol perturbé par l'établissement d'une liaison hydrogène

The improved LCAO method is used to study the electronic structure of phenol, phenoxide ion, and phenol perturbed by a hydrogen bond. The calculated transition energies are in good agreement with experiment. A new method is proposed to determine the differences of reactivity between the different atoms of the aromatic ring. The results are satisfactory.     

Applications analytiques de la phénothiazine

Spot tests carried out with the help of phenothiazine as reagent permit the detection of silver on a drop plate or on paper. D = 10^-5 or even 6.7.IO^-6 with a little less certainty. The reactions obtained are described in detail in the case of palladium, gold and platinum. Use of the reagent allows the detection of iron in presence of uranium (0.15γ iron in 0.053 ml in the presence of 107 times its weight of uranium). It also enables mercury to be detected in the presence of silver, even in the case of silver which is practically free from mercury. Finally, by the combined use of phenothiazine and diphcnylcarbazide it is possible to detect 0.54γ of silver in the presence of 100 times its weight of mercury.     

Synthese et caractérisation de catalyseurs a base de cuivre: application a la réaction d'oxydation du phénol

Synthesis and characterization of copper catalysts: application to the oxidation of phenol. The catalytic oxidatin of organic pollution has already been treated several publications reporting the use of ozone, air or hydrogen peroxide as oxidants. These systems require very severe conditions of temperature and pressure. It was thus useful to develop active, stable and inexpensive oxidizing systems. For this purpose we prepared catalysts by impregnation of copper on a natural clay; these catalysts were characterized, then used in the reaction of oxidation of phenol in the presence of hydrogen peroxide, at atmospheric temperature and pressure. The results showed a very significant activation of hydrogen peroxide by the catalyst, the phenol depletion percentage reaching 65 % after 4 h, and very significant stability of the catalyst.     

Dosage polarographique de la tyrosine,du tryptophane et de la phénylalanine en présence les uns des autres

A polarographic method is described for the determination of tyrosine, tryptophan and phenylalanine in mixtures, in which the animo acids are first converted to their nitro derivatives. Under suitable conditions each of these animo acids can be determined in the presence of the others.     

Traitement électrochimique d' eaux usées chargées de phénol : étude comparative sur des électrodes de dioxyde de plomb et de platine

Electrochemical treatment of waste water containing phenol: a comparative study on lead dioxide and platinum electrodes. The objective of this work was to study the efficiency of the Pb/PbO₂ electrode for decomposing the molecule of phenol, then to compare it to a platinum model electrode. Preliminary investigations by cyclic voltammetry showed that the Pb/PbO₂ anode presents a good chemical and electrochemical stability and possesses a high oxygen overvoltage. The study also showed that the electrochemical oxidation of phenol on Pt and PbO₂ in acidic media is a complex process. Long-time electrolysis was carried out using a three potential-plateau program with different values of the oxidation potentials and different concentrations of phenol. The obtained results showed that the transformation of phenol is total on the Pb/PbO₂ anode and that it is partial on Pt. On the other hand an increase in the phenol concentration decreases the rate of its conversion on the electrodes.     

Application de la chrono-ampérométrie par redissolution anodique au dosage de traces d'acétate de triphényl-étain

Using a hanging dropping mercury electrode (according to Vogel) the autliors find a better sensitivity of measurements in the determination of triphenyl tin acetate as fungicide residues on vegetable inatter.     

Configuration et conformation des produits issus de la réaction d'un thioacétate d'alkyle sur une diphényl-1,3-propène-2-one-1 substituée en 2

The reaction of methyl or ethyl thioacetate with a 2-substituted 1,3-diphenyl-2-propen-1-one proceeds stereospecifically giving in each case a single product although eight diastereoisomers are possible, The i.r. and PMR spectroscopic properties of each product have been studied. For each case, the data enable a determination of the stereochemistry of the product. The configuration and conformations are specified.     

Propriétés magnétiques de phosphates et silicophosphates de titane

The magnetic properties of titanium phosphates ATiP₂O₇ (A=Na,K,Rb), A₂Ti₂(PO₄)₃ (A=K,Rb), BaTi₂(PO₄)₃ M g₃Ti₄P₆O₂₄ and titanium silicophosphates ATi₃P₆Si₂O₂₅ (A=K,Cs) have been investigated by magnetic susceptibility and electron spin resonance measurements. All the compounds are paramagnetic and the thermal variation of the susceptibility can be described with a Curie-Weiss law χ_m=χ₀+ C_m/T−θ_p. The values of μ_eff per Ti⁺³ and the spectroscopic data obtained from the 77K E.P.R. spectra are discussed as a function of the structural data.     

Synthèse et réactivité des dérivés de la 2,3-dihydro-3-hydroxy-2-phényl-1,5-benzothiazépin-4(5H)-one

New 1,5-benzothiazepinone derivatives have been synthesized. The cycloaddition of benzylazide with 5-propargyl-1,5-benzothiazepinone 7 gave compounds 9 and 10. The 1,5-benzothiazepinone 8 reacts with hydrazine to give 1,5-benzothiazepinone 11, which gave in hot acetic acid compound 12. The reaction of 3-chloro-1,5-benzothiazepinones 13, 14 or 15 with nucleophiles in DMF afforded the 2-benzylidenebenzothiazin-3-ones 16 and 17. The tosylate 18 gave the 1,5-benzothiazepinone 19 by reaction with N₃TMS in the presence of CsF in DMF.     

Approche du phénomène de galop par un modèle d'effort retardé et validation expérimentale

We consider the case of elongated cylinders submitted to a cross-flow. We propose a time delayed force model for the galloping oscillations for which the linear study allows to calculate the critical velocity with quasi-steady coefficients. The phase delay between force and position is based on the Strouhal number of the cylinder measured in static conditions. The experimental validation is presented on square and rectangular sections cylinders.     

Microdosage colorimétrique de la cystéïne et de la cystine

Thiofluorescein is bleached in alkaline medium by light but reforms its colour on reaction with —SH groups. This can be used for the colorimetric determination of cystine and cysteine in the micromolar range.     

Etude du phénomène de dépiégeage des ondes de densité de charge dans les systèmes de basse dimensionnalité

Numerical results of the behaviour of a low dimensional system show that the electric resistivity depends on the friction coefficient generated by the defects. We also show that the electric field dependence of the response time at different friction coefficients follows a power law. The divergence of the charge density wave response time near the threshold field indicates that depinning may be viewed as a dynamical critical phenomenon.     

Polymérisation et post-polymérisation de l'acrylate de méthyle en milieu précipitant

The radiation initiated polymerization of methyl acrylate was investigated under precipitating conditions in n-hexane In 10 and 25% monomer solutions, the conversion curves are auto-accelerated and post-polymerization is observed in the dark. The initial rate of this post-polymerization steadily increases with the degree of conversion reached during irradiation, suggesting that trapped growing chains are responsible for the effect. The post-polymerization was followed at 23, 40 and 60°. From the results, it is concluded that chain termination is negligible under such conditions. The addition of methanol to the monomer solutions results in decreased rates and in a reduction of the extent of auto-acceleration. No influence of any “matrix effect” could be detected in these systems.