Chimie organometallique : XII. Homologation du methanol par des catalyseurs homogenes derives du rhodium

Reaction of methanol, carbon monoxide and hydrogen in the presence of a rhodium catalyst gives the homologization product, ethanol, with a selectivity of up to 50%, for a H₂/CO ratio equal to 40. A mechanism for the reaction is suggested.     

Reactivite des perfluorohalogenoalcanes en presence de couples metalliques. Reactivite de perfluoroiodoalcanes sur des derives halogenes dans des solvants aprotiques dissociants (DMSO,DMF)

Perfluoroalkyl iodides (R_FI) react with organic halide in dissociants solvents (DMF,DMSO) in the presence of zinc-copper couple through an organometallic route; in this way C₆F₁₃Cl, C₆F₁₃CH₂CH₂I, (C₆F₁₃)₂Zn have been prepared.     

Homologation directe du cycle des porphyrines par les diazoalcanes

We describe the direct homologation of a zinc-porphyrin into homoporphyrins on reaction with disubstituted diazoalcanes. The reaction may involve a zinc-carbenoid. At lower temperature competition with N-substitution was observed. We also describe a new series of homoporphyrins in which the supplementary carbon is inserted into a pyrrolic αβ bond.     

Recherches sur la polymerisation des derives acetyleniques

The thermal stabilities of certain unsaturated polymers of the polyacetylene group, such as polyphenylacetylene, poly-p-chlorphenylacetylene and poly-p-methyl-phenylacetylene were investigated by the methods of thermal analysis. The kinetic parameters of the thermal decomposition reactions, e.g. the activation energy and order of reaction, were determined by the method of Freeman and Carroll. The polymers were synthesized by the photochemical polymerisation procedure, by ion coordination and polycondensation. Both the soluble and the insoluble fractions were studied.     

Les complexes halogenes d'iridium

The thermal analysis of sodium hexachloroiridate(III) obtained by the method indicated by us showed that the complex crystallizes with 10 water molecules which are lost in two steps: 8 and 2 water molecules, respectively. The final product of the thermal decomposition of the complex in an oxygen atmosphere is iridium(IV) oxide, while under inert gases metallic iridium is formed. Na₃(IrCl₆) · 10H₂O crystallises in the rhombohedral system witha=16.677 Å andα=100°01′, space group R 3 m, d=2.29 and Z=9. A monoclinic pseudolattice was observed witha=8.338 Å,b=10.15 Å,c=12.52 Å andβ=107°06′ andZ=2.     

Derives halogenes d'etain chiraux avec des groupes diastereotopes anisochrones en RMN

New chiral halotin derivatives with a diastereotopic anisochronous group bonded to the tin atom have been prepared. The rate of halogenhalogen intermolecular exchange is very low compared to the values found uptill now.     

Etude des derives du benzene chrometricarbonyle par spectroscopie photoelectronique

The effect of substitution on the aromatic ring in arenetricarbonylchromium complexes was studied by ESCA. The chemical shifts of the core ionisation energies (C 1s, O 1s, Cr 3s) of these derivatives have been measured and information on the bonding in these complexes have been obtained.     

Etude sur le comportement thermique de quelques polymeres ignifugeants contenant du phosphore et des halogenes

The thermal behaviour a series of polyphosphonates was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The obtained data permitted the calculation of activation energies and reaction orders on decomposition zones by the Coats — Redfern method.     

Action des derives du phosphore tricoordonne sur les germanones et germathiones: Oxydation des phosphines

Desulfuration reactions of germadithiolanes by trialkylphosphines lead to germathiones via intermediate germathietanes. The formation of germylenes finally observed arises from reduction of germathiones by trialkylphosphines. Analogous reduction reactions of germanones by three coordinated linear and cyclic phosphorus compounds are also described.     

Corrosion par piqures du titane en milieux aqueux halogenes. Cinetique de croissance et morphologie des piqures

Pitting corrosion of titanium, studied under potentiostatic conditions, is only occurring at high potentials in halide aqueous solutions; valence of dissolution of titanium in pits is about 4. Pits growth kinetic can be described by i = ktⁿ laws (n = 1,5 for the main stage of growth). Metallographic examination of pits associated with these results leads to propose a geometrical model of pits growth. Pits with hemispherical cap shape are growing under a passive film the nature of which, probably saline, should ascertain the polygonal edges of some pits by anisotropic dissolution of the film. On non anodically passivated titanium, interstitial or crevice type pitting corrosion observed on passivated surfaces, is occurring with increased sharpness.     

Sels de cobalticinium: I. Synthese des derives homo- et hetero-disubstitues

Unlike ferrocene, cobalticinium cation is chemically inactive towards electrophilic substitutions and for this reason the number of derivatives in this series is limited. Substituted cobalticinium salts are usually prepared indirectly from substituted cyclopentadienyl derivatives. These intermediates can be obtained by treating substituted cyclopentadienes with strong bases or by reducing fulvenes. Various homo- and hereto-substituted cobalticinium salts have been prepared using this type of reaction. Due to the remarkable stability of the metallocenic skeleton of cobalticinium ion, we have succeeded in obtaining new derivatives transforming ring-substituted cobalticinium salts by known reactions.     

Conversion des furfurylalkyl et arylcetones en derives de l'isocoumarine et de l'isoquinoleine

Cycoladducts of furfurylakyl and arylketones with methyl acetylendicarboxylate undergo acid-catalysed rearrangement in high yield to 6-hydroxyphthalates bearing an acetonly or a phenacyl group in the 3-positionl. These phthalic compounds are useful intermediates for the synthesis of polyfunctional derivatives in the isocoumarin and the isoquinoline series.     

Stereochimie de l'addition des derives zinciques des ethers propargyliques sur les composes carbonyles

The stereochemistry of the addition of the zinc derivative of ether PhCCCH₂OMe, to aldehydes and ketones has been studied. In the case of saturated carbonyl compounds, the results can be explained by a mechanism which takes into account the steric effects of the substituents. However, with those which contain phenyl, vinyl or alkynyl groups in the α position, conformational and electronic factors must be considered.     

Alcoolyse et glycolyse de derives organozinciques et organocadmiens par des composes chiraux

The reaction between organozinc or organocadmium derivatives and different chiral hydroxy compounds leads to the corresponding alcoholates and glycolates which can be used as initiators in polymerizations.The composition of such initiators is defined by the ratio i_S = R-M-O/O-M-O of the number of alkylalkoxy groups to the number of dialkoxy groups. This ratio depends on the nature of the organometallic and hydroxy compound and on the conditions of reaction used to prepare them.Toward a given hydroxy compound, the reactivity of the organometallic derivatives follows the order: ZnEt₂ > CdEt₂ > CdMe₂.Primary alcohols and 1,2-diols are more reactive than secondary alcohols in the case of organozinc compounds, while in the case of organocadmium compounds the secondary alcohols are more reactive than primary alcohols, but less reactive than 1,2-diols. The kinetics of the reaction can be followed by monitoring the variation of optical activity of the solution.Several compounds having definite stoichiometry have been isolated and identified by their NMR spectra.     

Reactivite multiple des amines stannique: cas de certains derives carbonyles conjugues

en]Organotin amines react with α-enones to give various products depending on the nature of the initial carbonyl derivatives. 1,2 or 1,4-addition or, abstraction of an hydrogen from the α position were observed; each kinetic product being able to form a more stable species.     

Analyse conformationnelle de derives du thiophane,des sulfoxydes et sulfones correspondants

The conformations of biotin 1, cis 3,4-isopropylidenedioxythiophane 2, its 2,5-methylated homologs, 3, 4 and 5 and those of the corresponding sulfoxides and sulfones have been studied by NMR. Coupling constants, temperature and solvent effects show that all these compounds exist in a highly preferred conformation, the thiophane being in the envelope form with the sulphur atom out of the plane. In series 1, 2, 3 and 5 the arrangement is of the “boat-chair” type, in series 4 of the “crown” type, the sulphur being respectively cis and trans with respect to the other ring.     

Addition des ylures de carbonyle derives de gem-dicyanoepoxydes sur les benzylidene anilines substituees

The reaction of substituted benzylidene anilines with 1,1-dicyano or 1-cyano 1-ethoxycarbonyl epoxides gives oxazolidines, the structures of which is established by NMR spectroscopy. The formation of oxazolidines proceeds via regiospecific addition of epoxide derived ylid to imine. The influence of ylid substituants and imine substituants on the reaction may be interpreted by interactions of the frontier orbitals.