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.     

Le rearrangement de claisen en series siliciee et germaniee: silaethylene et germaethylene

Thermolysis of silicon and germanium isologues of allyl aryl ethers via transient metal π-bonded intermediates leads to aromatic Claisen-type rearrangement. Para-Claisen type reaction is not observed when the aromatic ring is ortho-disubstituted. In that case the Cope rearrangement is replaced by a radical process. The Claisen rearrangement leads to new oxametallacylohexanes by intramolecular trapping of the metal-carbon double-bond, when the homolytic process gives rise to new oxametallacycloheptanes.     

Action des phenylacetonitriles α-substitues sur les tetrahalomethanes en milieu basique: Mecanismes de l'halogenation et de la duplication

Carbanions of substituted phenylacetonitriles are halogenated by carbon tetrachloride or carbon tetrabromide, and also converted into symmetrically-substituted succinonitriles. The halogenation occurs via an ionic process, and the formation of succinonitriles via a radical process, essentially a no-chain mechanism in the case of diphenylacetonitrile anion, confirmed by the course of the reaction of p-nitrobenzylchloride on the diphenylacetonitrile anion.     

Action de l''hydroxylamine, de l''hydrazine et de ses derives sur les γ-pyrones

The reaction of hydroxylamine and hydrazine on γ pyrones was generally reported to yield various heterocycles in which nitrogen is incorporated. More recently, several authors have reported that γ-pyrones oximes and hydrazone derivatives can be obtained and have settled some controversial previous results. This report presents a review of this question.     

Influence de la temperature sur les associations moleculaires et sur la polymerisation de l'acide acrylique en solution

Infra-red spectra of pure acrylic acid and solutions of monomer in toluene indicate that increasing the temperature from 20 to 60° displaces the equilibrium of H-bonded species from cyclic dimer to open oligomer. Viscosity measurements on the same solutions confirm this conclusion. In methanol solutions. alcohol-alcohol and alcohol-acid associations are found together with the acid-acid associations and the interpretation of the results is extremely difficult. Polymerization kinetics are directly influenced by the shift of association equilibria. In hexane, an increase in temperature results in a sudden increase in reaction rate as the linear oligomeric structures appear in the solution. In methanol increase in temperature reduces the kinetic anomalies observed at 20 and the polymerization no longer exhibits any stereospecificity. At the same time, a chain transfer process sets in. These various results confirm the earlier assumption of an assisted propagation step occurring in auto-associated aggregates of acrylic acid.     

L'extraction des lanthanides et des actinides par les oxydes d'alkylphosphine : L'extraction de L'acide nitrique par les oxydes de tri-n-hexylphosphine,de tri-cyclohexylphosphine et de tri-n-octylphosphine

The distribution of nitric acid between an aqueous phase and a solution of THPO, TcHPO and TOPO in benzene was measured at 25°. The apparent stability constants K₁' were found to be 17.2±1.0 (M)^-2 for THPO.HNO₃, 7.0±0.8 (M)^-2 for TcHPO.HNO₃ and 15.2 ± I.I (M)^-2 for TOPO.HNO3. The stoichionetry of the last complex was confirmed in n-octane solution at constant ionic strength in the aqueous phase.     

Action du fluorure de potassium sur les tosylates α-fluores: Synthese et proprietes de derives 1,2-difluores.

Fluorinated alcohols, synthesised from epoxides by action of trimethylamine fluorhydrate, can be transformed to 1,2-fluorotosylates when they are treated with tosyl chloride in pyridine. The physico-chemical propreties of these fluorotosylates are studied. The action of KF, in diethylen glycol, on these α-fluorinated tosylates gives the corresponding 1,2-difluorinated compounds in good yield. The stereochemical course of the last reaction can be elucidated from an analysis of the ¹⁹F NMR of the 1,2-difluorocyclohexane.     

Action du chlorure d'acetyle et de l'anhydride acetique sur le nitronate de lithium derive du phenyl-2 nitroethane : Reactivite electrophile ou dipolaire,en fonction du milieu,de l'oxyde de nitrile intermediairement forme

The lithium nitronate salt derived from 2-phenyl nitroethane reacts with acetic anhydride and with acetyl chloride to give an intermediate nitrile oxide. Depending on the protonating character of the medium, this latter can react either as a 1,3 dipole to give the furoxan or, in the presence of a dipolarophile, the corresponding adduct ; or as an electrophile leading to the chlorooxime or to derivatives of benzohydroxamic acid. The formation of the nitrile oxide, by loss of acetic acid from a nitronic-acetic mixed anhydride, appears to be the most plausible reaction pathway accounting for the above observations.     

Action des derives du phosphore trivalent sur les composes a halogene positif—X : Action des phosphites d'aryle,phenylphosphonite de diphenyle et diphenyl phosphinite de phenyle sur les α-halo α-cyanosuccinimides et les αα′-dihalo αα′-dicyanoglutarimides

3-Bromo-3-cyanosuccinimides 1 and 3,5-dibromo-3,5-dicyanoglutarimides 17 react with P(OPh)₃, Ph₂POPh and PhP(OPh)₂ to yield quasiphosphonium salts. The glutarimide adducts were transformed rapidly into 2,6-dibromo-3,5-dicyano-1,4-dihydropyridines 22. 3-Bromo-3-cyano-1-methylsuccinimide and P(OPh₃) yields an oxazaphosphorane 6. An equilibrium exists between oxazaphosphoranes and iminophosphoranes for adducts formed from succinimides and PhP(OPh)₂ or Ph₂P(OPh).     

Réactions de germylènes avec divers oxirannes et le thiiranne. Mise en évidence de germanones et germathiones intermédiaires. Communication préliminaire

Complexed dialkylgermylenes R₂GeNR₃ or R₂GePy react with oxiranes or thiirane and lead to dialkylgermanone and germathione via germaoxetanes or germathiacyclobutane. The formation of germadioxolanes or germadithiolane finally observed arises from condensation of dialkylgermanone (or germathione) on oxiranes (or thiirane).     

Additions electrophiles sur les esters acetyleniques et alleniques—IV : Addition des halogenes et des halogenures de sulfenyle sur le butyne-3 oate d'ethyle

Ethyl but-3-ynoate undergoes electrophilic additions of BrCl and of ICl to give CHXCClCH₂COOEt E (X = Br or I). The addition of sulfenyl halides RSY follows the opposite orientation and leads to CHYCSRCH₂COOEt E (Y = Cl or Br, R = Et or Ph). In the case of IBr, both CHICBrCH₂COOEt E and CHBrClCH₂;COOEt E are obtained.A mechanistic interprétation of these results is supported by both the orientation and the kinetic order of the addition: PhSCl reacts by an Ad_E2 process, whereas ICl addition involves a combination of Ad_E3 and Ad_E4 mechanisms.     

Diffusion rayleigh depolarisee en serie organosilicique : I. Anisotropies optiques de liaisons et de groupes organiques et organosiliciques

The authors show that C---H, C=C, C---O, C---N, Z---CMe₃ (Z = C_sp³, C_Ph, N, O), C_Ph---Me, C_Ph---SiMe₃ and N_py---SiMe₃ bond optical anisotropies are positive as for the C---C bond.     

Action du magnesium sur les nitriles ω-halogenes : Synthese de cyclanones

δ- and ?-Iodonitriles react with magnesium in ether at room temperature to give substituted cyclopentanones and cyclohexanones by intramolecular cyclisation.     

Action de O- et N-nucléophiles sur les sels de phényl-3 benzopyrylium-1

3-Phenyl-1-benzopyrylium percholorates 1a, 1i react exculusively at C-2 with ethanol and isopropyl alcohol, affording mixed acetals 2a, 3a, 3i . Aqueous ammonia gives symmetrical secondary amines 4a, 4b or bis(3-phenyl-2H-1-benzopyran-2-yl)amines, while with aqueous aliphatic amines (40%) bis-acetals 5a, 5b or 2,2′-oxy-bis(3-phenyl-2H-1-benzopyrans) are characterized. In some other acidic conditions, 5a and 5b are also obtained.     

Reactivite chimique et photochimique dans les milieux micellaires et les microemulsions—III : Mise en evidence de l'importance des processus interfaciaux sur une reaction de photoisomerisation

The E ? Z photoisomerization of the O-methyl ether of the oxime of 2-acetylnaphthalene has been studied in various microemulsions. The results obtained with variations of surfactant concentrations or with addition of sodium chloride show the importance of interfacial processes in colloïdal systems.