Etude de la copolymerisation radicalaire entre l'anhydride maleique et le trans stilbene et des copolymeres resultants

Maleic anhydride with trans stilbene forms a charge transfer complex (CTC). In their copolymerization, the reaction proceeds to a maximum yield dependent upon the experimental parameters. The activation volume found from a pressure study indicates a compact transition state, in agreement with the possible existence of a penultimate effect which appears mainly for feed compositions rich in anhydride. The thermal stability and the hydrolysis of the copolymers were also briefly investigated.     

Alcoylation par l'iodure de butyle,de l'enolate de tetrabutylammonium de l'acetylacetone; nature de l'entite reagissante

The alkylation of tetrabutylammonium acetylacetonate with butyl iodide was studied in order to specify the nature of the reactive anionic species during the nucleophilic reaction of an ambident anion, under similar conditions to those of phase transfer catalysis. The C/O alkylation ratio changes with neither the solvents nor the enolate concentration; however k_obs, varies with the solvent but does not depend on the énolate concentration. The results and spectrophotometric UV data show that only one reactive species, the ion-pair, is involved.     

Dosage de l'hydrogene,de l'azote et de l'oxygene dans le monocarbure d'uranium

A method is described for the determination of hydrogen, oxygen and nitrogen in uranium monocarbide. Hydrogen and oxygen are determined by the classical or modified “Platinum flux” method at 2000° with a coefficient of variation of 10%. Nitrogen is determined at 2000° by the modification of the “Platinum flux” technique. The results obtained are in agreement with those found by Kjeldahl analysis. The coefficient of variation is about 10%. A procedure for the simultaneous determination of the 3 gases is given.     

Insertion de l'anhydride sulfureux dans la liaison carbone—cuivre

Alkylcopper reagents add sulfur dioxide at ?40°C and high yields of sulfinic are obtained. Copper sulfinates are easily oxidized by bromine to the corresponding sulfonyl bromides.     

Etude theorique de la cycloaddition de l'ozone sur l'ethylene

A theoretical study of the cycloaddition of ozone on ethylene has been carried out by the LCAO-SCF-MO method. The potential energy hypersurface for the reaction has been investigated and the electronic and energetic properties of the transition state have been determined.     

Etude de l'action de l'ion fluor sur la laquethorium-spadns

The reaction of fluoride with thorium—SPADNS lake was studied in detail with particular reference to the effects of pH and media. Two methods for the determination of microgram amounts of fluoride based on the reaction are described. The spectrophotometric method developed is more suitable for routine use, but the colorimetric titration method is less sensitive to the effect of large amounts of electrolyte.     

Sinthese de copolymeres sequences de l'acetate de vinyle et de l'acrylate d'ethyle par telomerisation

A new two-step procedure for the synthesis of ethyl acrylate - vinyl acetate block copolymers is described : the first stage is the telomerisation of ethyl acrylate with carbon tetrachloride by redox catalysis, the second being another telomerisation of vinyl acetate, using the trichloromethyl end group of the first block as the telogen agent, with peroxydic initiation.     

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.     

Oxydation chromique de l'adamantanone : preparation de l'acetoxy-5 adamantanone-2

chromic oxidation of adamantanone gives adamantane-2,6-dione (20%), 5-hydroxy adamantan-2-one (6%) and 5-acetoxy adamantan-2-one (36%).     

Etude de l'equilibre entre l'oxyde de nickel et l'oxygene. Essai d'interpretation des lois de variation de la conductivite electrique en fonction de la temperature

In a previous paper we have shown that at 740°C and under an oxygen pressure less than 1,3 torr the electrical conductance G of a NiO powder reaches rapidly an apparently stabilized signal G_i which sharply decreases after a sufficiently long time to a G₀ value independent of P_O2.From this observation we have studied the influence of the temperature successively on the electrical conductance G_i and G₀. The Arrhenius law is only verified for the G₀ = f(T) curve. G₀ appears as the representative value of the gas-solid equilibrium.     

Cyclisation radicalaire de la desoxy-2′-adenosine en solution aqueuse,sous l'effet du rayonnement gamma

5′,8-Cyclo-2′-deoxy-adenosine 2 has been identified as one of the principal products of gamma radiolysis of 2′-deoxyadenosine (G = 0.03 in the presence of oxygen; G = 0.05 in the absence of oxygen). This compound is likely to play a role in the phenomena of radio-induced mutation. ¹H-NMR studies at 250 MHz have shown the remarkable geometry of the compound since three coupling constants of the vicinal protons of the sugar fragment have not been detected. The study of the model has in fact shown that the corresponding protons form an angle close to 90°. The formation of 2 shows that the C8-N7 double bond is attacked by the radical on the carbon 5′ of 1, produced by the action of OH· radicals formed by the radiolysis of water.