Influence de la Structure de Diverses Fonctions sur l'Evaluation de l'Energie de Correlation

The influence of various correlation functions, multiplying the monoelectronic space function, is studied and applied to the Helium atom and its isoelectronic series. We used Slater-type basis orbitals and the ground and first excited states have been studied, taking into account the virial and cusp conditions. In the ground state, a very good value for the correlation energy is obtained, using a function of the type For the excited states, this type of function overestimates the assumed value of the correlation energy.     

Étude thermodynamique de la complexation de `l'argent par la pipérazine et quelques-uns de ses dérivés en milieu aqueux

The stability constants of the complexes formed by Ag⁺ ion with piperazine and its 2-methyl-, N-methyl-, and N-phenyl-derivatives were determined in aqueous 0.1 M KNO₃ solution at 25°C, by means of the corresponding metal—complex electrodes.The direct calorimetric study of these reactions in the same conditions of temperature and medium made it possible to calculate the standard enthalpies and standard entropies of formation of the complexes.On the basis of a comparison of all the thermodynamic functions of these systems, the ability of each ligand to coordinate is discussed.     

Halogénures Alcalins: Un Modèle Incluant une Délocalisation à Courte Distance Application à la Stabilité Relative des Divers Arrangements Cristallins

The introduction of symmetry-adapted hybrid atomic orbitals on the metallic atoms allows us to divide the crystal into elementary cells which contain 8 valence electrons each. These cells are described by linear combinations of the halogen valence shell s and p orbitals and the hybrid orbitals of the nearest metallic atoms which point to the halogen. The electronic delocalization of the halogen ions is very weak (?0.02) for: LiF, NaF, KF, LiCl, NaCI, and KCI. The cell energy in the crystal is obtained by using a first-order perturbative treatment. In agreement with experiment, the f.c.c. type is found more stable than the b.c.c. or the blende type.     

β-Dicéto énamines hétérocycliques: 2. (Pyridyl-4)-2 indanediones-1,3 C-et N-substituées

The authors have studies the regulation of the position of substitution in 2-(4-pyridy)-1-,3-indandiones and the precise methods for introducing functionalised substitutents on teh dihydropyridine nitrogen. These N-substituted compounds can also be synthetised by (a) condensation of momo- or polymethlated pyridines on dialkyl and monoalkyl phthalates and (b) by the oxidative condensation of Nalkylpyridinium btomides on 1,3-indandione. The negative solvatochromy observed in the electronic spectra of the N-substituted 2-(1,4-dihydrp-4-pyridylidèene)-1,3-indandiones leads us to propose a betaïne structure for these compounds.     

Le chlorure de polyvinyle: Un detecteur de traces interessant

Abstract

It is shown that polyvinyl chloride is a polymer of sensitivity comparable to that of cellulose nitrate. In this polymer the time when tracks appear depends critically upon ion energy and permits good discrimination.     

Induction asymétrique et réaction des α-hydroxy-oximes avec le bromure de phenylmagnésium. Synthéses stéreoselectives d'alcools aziridiniques et d'aza-bicyclo[3.1.0]oxo-2 oxaisothiazolidines-1,2,3

A facile synthesis of aziridine is describe. It is the reaction between Grignard regents and α-hydroxoximes in toluene. The aziridine alchohols are cyclised into 2-oxo-oxathiazolidines. The use of the nuclear Overhauser effect allows the assignment of the relative configurations of these latter compounds and also the configuration of the aziridine alcohols. A proof of the Grignard reagent complex with the alcoolate id given by action of methylmagensium bromide with 2-phenyl 3-methanol azirine. The asymetrie insuction observed is discussed with a transition state involving this complex.     

β-Dicéto énamines hététrocycliques: 1. Indanediones-1,3 substituées en 2 par un hétérocycle azoté

The condensation of methylated N-heterocycles and espically monomethyl- and polymethylpyridinets on phthalic enhydrides leads to 2-ary1-1,3-indanediones. The 3alklidenylphthalides formed in an intermediary state have been isloated. The influence of solvents and temperature on the velocity and yeild of formation of 2-(2- and 4-pyridyl)-1,3-indandiobnes has been studies. The ir and nmr spectra confirm taht these compunds exist under a β-diketoenamine form resonating witj a betaine form.     

Farbenreaktionen des Pilokarpins

Ohne Zusammenfassung     

Aziridines. V. Etude par rmn de l'inversion de l'azote dans les aziridines symétriques à fonetion amine secondaire

This article describes the nitrogen inversion in two symétrie secondary aziridines. It was possible, by nmr, in avoiding the exchange of NH proton with water, to record spectra at different temperatures and to determine the temperature of coalescence. Persistance of coupling H? C? N? H after coalescence demonstrates the attribution of signals multiplicity to both invertomers.     

Controle de l'enrichissement de l'uranium metallique a l'aide du nitrate de cellulose

Abstract

Le nitrate de cellulose permet d'enregistrer le passage de particules α done de mesurer l'activité spécifique d'une source radioactive épaisse. Nous utilisons cette propriété pour mesurer le taux d'eorichissement en uranium 235 d'un éhantillon d'uranium métallique. Afin de faciliter la mesure et de s'affranchir de la lecture du nombre de traces au microscope optique, les échantillons sont révélés dans un bain spécial et le nombre de traces α par unité de surface est évalué en fonction du pouvoir réflecteur de l'échantillon.

Les moyens et le temps nécessaires pour une mesure sont, ainsi que le prix de revient, très réduits.

Cellulose nitrate can be used for the registration of α-tracks and therefore for the measurement of the specific activity of thick radioactive sources. This characteristic is applied to the determination of ²³⁵U enrichment rate of metallic uranium samples. For the measurement of track density a method is developed which replaces the counting procedure under a microscope. The samples are etched in special solutions and track density is evaluated from the diffuse reflecting power of the samples.

The main advantages of this method are its rapidity, easiness and low cost.