Heterocyclisation intramoleculaire d'alcools possedant un squelette cedranique. Oxydation par le tetraacetate de plomb et par l'oxyde de mercure et le brome

Oxidation with lead tetra-acetate of neoisocedranol yields the corresponding ether in good yield. Under the same conditions, cedrol remains unchanged; however, when cedrol is reacted with mercuric oxide and bromine, the corresponding ether is obtained as major product. The structure of the substrates is linked with the mechanism of the two reactions and with the nature of the intermediates in the heterocyclisation reaction. The difference in behaviour between the two substrates towards the two oxidising agents is rationalized.     

Etude de l'action des alkylmagnesiens primaires et arylmagnesiens sur les anhydrides tricycliques pontes

The reaction of primary alkyl and aromatic Grignard reagents with bridged tricyclic di-carboxylic anhydrides gives the corresponding dialkylated tricyclic lactones via di-addition process. The lactones were transformed by retro-Diels-Alder reactions into 4,4-dialkylated butenolides.     

Forme des cristallites d'oxyde de cadmium produits par decomposition de l'hydroxyde

The structural transformation that occurs in the cadmium hydroxide decomposition reaction has the morphological and crystallographic character of a martensitic transformation. The authors predict the shape of the oxide crystallites produced during the reaction, viz., small platelets developed parallel to the (111) oxide planes. The difficulty in assessing their shape by analysis of X-ray diffraction line profiles is discussed. Electron microscope and X-ray diffraction results are presented and it is shown that the oxide crystallite shape is dependent on whether the precursor is hydroxide or carbonate.     

Preparation d'esters par deshydrogenation d'alcools primaires en phase liquide catalysee par l'oxyde de cuivre - observations preliminaires

Linear primary alcohols with at least 7 carbon atoms are quite quantitatively transformed in esters, by CuO, at temperatures > 170°, without air in liquid phase. Preponderant influence of carbon in position 2 is evidenced. In the same conditions lactones are obtained from diols, and benzylic alcohols undergoes, by hydride transfer, a disproportionation into toluene, benzaldehyde and water.     

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.     

Reduction asymetrique de cetones par des alcoxyaluminohydrures chiraux prepares a partir de l'ephedrine et divers alcools ou phenols achiraux

The effect of the nature of the achiral component R′OH on the stereoselectivity of the asymmetric reduction of acetophenone by [LiAlH(OR′)₂(N-methylephedrine)] is examined. 3,5-Dimethylphenol as achiral component proved to be very suitable for making optically active secondary alcohols in high optical yield.     

Etude des solutions solides d'oxyde de lithium dans l'oxyde de nickel. II. Influence de la pression d'oxygene et mecanismes d'incorporation

The formation of solid solutions of lithium and nickel oxides, containing more than 2 at Li %, requires the presence of oxygen under a pressure which must exceed 10^?3 torr at 933 K. Solid solutions containing a maximum of 2 at Li % however can be prepared under a reduced pressure of oxygen (< 10^?4 Torr). Mechanisms are proposed to explain, in both cases, the incorporation of lithium ions in the nickel-oxide lattice.     

Oxydation d'alcools ω-vinylalléniques par l'hydroperoxyde de tertiobutyle

The oxidation of α-vinylallenic alcohols 3 with t-butyl hydroperoxide in the presence of catalytic amounts of vanadyl acetylacetonate, yields the epoxides 6 or, mainly, the cyclopentenones 5 depending on the secondary or tertiary class of the alcoholic function. In the same conditions, the vinylallenic alcohols 4 lead only to cyclopentenones 7.     

Catalyse par des complexes du nickel l'electrosynthese de 1,1-diarylethane a partir d'halogenures aromatiques et d'ethylene.

In mixed THF-HMPA, the electrochemical reduction of nickel bromide leads to catalytic nickel very efficient towards the electro-reductive coupling of ethylene with arylhalides yielding 1,1 diarylethane as the main product.     

Action des sulfonyloxaziridines sur une imine. Obtention d'une nitrone par transfert regioselectif de l'oxygene sur l'azote

A pyrrolinic imine has been found to react concurrently with the nitrogen or the oxygen of a $\text{N}$-sulfonyl oxaziridine leading to a N-sulfonyl diaziridine and a nitrone respectively. By contrast an oxaziridine is obtained with a peracid. A possible relation between the regioselectivity of the oxygen transfer and the nature of the reagent is outlined.     

Separation des alcalino-terreux par l'edta sur resine echangeuse d'ions

The quantitative separation of a few mg of strontium and barium from several g of calcium is described. The alkaline earth carbonates are dissolved in 0.1 M EDTA, fixed at pH 4.8 on an ammoniacal Dowex column, and eluted, also with 0.1 M EDTA, calcium at pH 5.25, strontium at pH 6.0, barium at pH 9.0. The end of the calcium elution can be followed accurately by a sudden pH increase in the eluate(from 4.8 upto 5.25).     

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.     

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.     

Etude des solutions solides d'oxyde de lithium dans l'oxyde de nickel. I. proprietes des solutions solides preparees sous pression reduite d'oxygene

Heating mixtures of lithium and nickel oxides at 1073°K under reduced oxygen pressure (<10^?6 Torr) produces the incorporation of lithium ions in the nickel-oxide lattice. The solubility appears to be limited at 1.9 at Li %. From a study of several properties of solid solutions, it is concluded that the incorporation of lithium ions creates and stabilizes anionic vacancies.