Nouveaux diphosphenes: Synthese et caracterisation

Two new diphosphenes (RPPR′) are obtained quantitatively in exchange reactions between disilylated phosphines and dichlorophosphines; the products are characterized by their cycloadducts on 2,3-dimethylbutadiene.     

Reactions des n-phtalimidyl et n-succinimidyl iminophosphoranes avec les composes a triple liaison; acetyleniques actives et α-halonitriles

N-Imidyl iminophosphoranes 1 and 2 with electrophilic acetylenic compounds 5 yield phosphoranes that spontaneously gives ring closure with one of the imidyl carbonyl groups. If this imidyl substituent is an unsymmetrically substituted succinimide, the carbonyl group with less steric hindrance undergoes cyclization. Phthalimidyliminophosphoranes react with some α-halonitriles (i) on the positive halogen if the nitrile group is sterically hindered (halonitriles 8a and 8b); (ii) with the nitrile group of 13, which gives an iminophosphorane 14 that has no action on carbonyl groups of imidyl substituent.     

Nouveaux modeles polysilicies a partir d'indoles,du benzothiophene et du benzofuranne

Direct polysilylation of bicyclic heterosubstrates was performed without (in the case of indole or its N-methyl or N-trimethylsilyl derivatives) or with (benzothiophene, benzofuranne) ring-opening. Hexasilylation from benzothiophene occurred with desulfurization.     

Nouveaux polyéthers et polyesters à base d'isosorbide: synthèse et caractérisation

A new family of multifunctional polyethers was synthesized with acceptable yields by condensation of isosorbide with aliphatic and aromatic dihalides in solid-liquid heterogeneous medium (solid KOH in DMSO). Molecular weights evaluated by GPC are rather low (polydispersed oligomers with n = 2–9). On the other hand, polycondensation with aliphatic or aromatic acid dichlorides in mass or in solution allowed the elaboration of polyethers with appreciable weights (4000–8000) in good yields.     

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.     

Aziridines N-non substituées: XI—Inversion de l'azote dans des composes C-substitués symetriquement ou non de part et d'autre du cycle

The occurrence of nitrogen inversion in 2- and/or 3-substituted aziridines has been proved by ¹H n.m.r. Only one invertomer was found when the difference in the bulkiness of the substituents on opposite sides of the ring is very great. From the different chemical shifts and the coupling constants of HC? NH one can show that the preferential invertomer, or the only invertomer, is always the one that has the N? H proton on the least hindered ring side. For the symmetrically substituted aziridines the energy barrier measurements have shown a decrease in the energy of the inversion as the steric hindrance of the molecule increases. A new stabilization factor, due to the preferential conformations of the aromatic ring, was found for the invertomers of phenyl substituted aziridines.     

Synthese de Nouveaux Derives Phosphones a Chaine Perfluoree et Leurs Proprietes Adhesives Sur Acier

Ce mémoire décrit la synthèse de phosphonates comportant une chaîne perfluorée. Ces composés sont obtenus par la télomérisation d'allylphosphonates de dialkyle en présence d'un agent de transfert fluoré de type mercaptan. Ensuite, nous employons deux méthodes de déalkylation menant sélectivement soit au monoacide soit au diacide phosphonique. Tous ces produits comprenant une extrémité de chaîne phosphonée, sous forme acide ou ester, ont été caractérisés et leur adhésion respective sur des plaques d'acier est étudiée. Ces tests montrent que le monoacide phosphonique est un excellent promoteur d'adhésion et qu'il est aussi efficace que le diacide. This article describes the synthesis of phosphonic derivatives bearing a perfluorinated chain. These compounds have been synthetized by telomerization of dialkyl allylphosphonate with a fluorinated transfer agent type mercaptan. Then two methods of dealkylation leading selectively were used to mono or to diacid phosphonic moieties. All the products bearing phosphonic end-groups, more or less acidic, have been characterized and their own adhesion on steel plates is studied. These tests show that phosphonic monoacid is an excellent adhesion promoter on steel, as efficient as the diacid compound.     

Remarques sur le microdosage du bore et du germanium dans les composes organiques et mineraux

A wet destruction in a Kjeldahl flask followed by spectrophotometric measurement with azomethine H as reagent, combustion in oxygen in a Parr bomb, and destruction by heating with sodium peroxide followed by acidimetric titration of the mannitol—boric acid complex have been tested for the microdetermination of boron in organic and inorganic compounds and compared with the Schöniger-flask method, which fails to give good results in the case of inorganic compounds; the wet-combustion method is the most useful. Similar techniques, combined with the acidimetric titration of the mannitol—germanic acid complex, or spectrophotometric measurement using phenylfluorone as a complexing reagent, or gravimetric determination as GeO₂, have been tested for the microdetermination of germanium, but none of them is entirely satisfactory, for reasons of lack of either universality or precision.     

Synthese et reactivite d'organomagnesiens perfluores. V.[1] Synthese et identification de nouveaux composes perfluoroalkyles du mercure a chaine longue.

The reaction of mercuric salts HgY₂ or organic mercuric compounds R_HHgX with long chain perfluorinated Grignard reagents R_FMgBr leads to a series of new perfluoroalkyl mercury derivatives with the general formula R_FHgZ (R_F=C₄F₉, C₆F₁₃, C₈F₁₇ ; Z=R_F,R_H,Y with Y = I,Br,Cl, NO₃,OCOCH₃,OCOCF₃).The synthesis of these organomercuric compounds is described, and their spectroscopic properties are reported.     

Intramolecular photoinduced electron transfer in a ruthenium polypyridyl functionalised β-cyclodextrin capped with a hydroxo bridged Cu(II) dimer

The synthesis of a novel donor–acceptor system comprising a ruthenium polypyridyl unit covalently linked to the secondary face of β-cyclodextrin which has a hydrxy bridged dinuclear copper(II) moiety on its primary face is described and the spectroscopic, electrochemical and photophysical properties of this complex are outlined. Photophysical studies demonstrate evidence for photoinduced electron transfer from the excited ruthenium to the copper centre. The rate of electron transfer, was estimated from luminescence lifetime studies to be 1.86 × 10⁻⁶ s⁻¹. The parent ruthenium polypyridyl functionalized β-cyclodextrin complex binds to both Cu(II) and Zn(II) in alkaline aqueous solution and the affects of these cations on the luminescence intensity of this complex is explored and compared with the photophysics of the isolated supramolecular complex. Whereas Cu(II) statically quenches the ruthenium centre, Zn(II) has little effect. This work suggests luminescent CD complexes, with long-lived luminophores may have value in metal ion sensing.     

Thermodynamique de composes azotes. VII. Etude thermochimique du pyrazole et de l'imidazole

Enthalpies of sublimation for pyrazole and imidazole have been obtained by calorimetry at 298.15K. The ΔH⁰_sub (298.15 K) values for these two compounds are, respectively, 69.16 ± 0.32 and 74.50 ± 0.40 kJ mole^?1. From literature data obtained by combustion calorimetry for ΔH⁰_f (c, 298.15 K), the enthalpies of formation of these compounds in the gaseous state (pyrazole: 185.1 ± 2.3 kJ mole^?, imidazole: 133.0 ± 1.7 kJ mole^?1) have been derived. Several energy values related to the molecular structure of these two compounds (as resonance energy, enthalpy of isomerization, …) have been determined. The study of pyrazole has enabled us to contribute to the evaluation of some characteristics of the NN bond.     

Nouveaux trioxophosphetanes generateurs d'oxygene singulet a basse temperature

We have prepared phosphite ozonides $\text{1b}$–$\text{3b}$ which are efficient and clean singlet oxygene generators at low temperature.     

Dosage de l'oxygene dans l'uranium et ses composes par la methode au monochlorure de soufre

A sulfur monochloride method is proposed for the determination of oxygen in uranium compounds. Sulfur monochloride reacts with oxygenated compounds at temperatures depending upon their nature; the sulfur dioxide produced is titrated by iodometry, after the excess reagent has been eliminated by a selective adsorption-desorption process using activated charcoal. This method has been successfully applied to uranium oxides (UO₂, U₃O₈), to mixtures of uranium dioxide with uranium, uranium nitride, and uranium carbide, and to substituted carbides (UC_1-xO_x). The results are generally satisfactory for oxygen contents higher than 500 p.p.m. However, in the presence of free or combined carbon, this limit is considerably higher. A loss of oxygen as carbon monoxide is also possible, and a simultaneous determination of carbon monoxide must be carried out. The relative error is of the order of a few per cent.     

Hydrogen peroxide photoproduction by the semicarbazide—tris(2,2′-bipyridine)ruthenium(II)—oxygen system

A light-driven system consisting of tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) as the photosensitizer, semicarbazide as the electron donor and molecular oxygen as the electron acceptor has been employed for hydrogen peroxide production. The efficiency of this photosystem markedly depends on pH: while the peroxide yield is almost negligible at acid, neutral or slightly alkaline pH, it reaches significant values at high hydroxide concentrations, the initial rate of H₂O₂ formation drastically increasing from pH 12 to pH 14. In 1 M NaOH solutions containing Ru(bpy)₃²⁺ and semicarbazide at optimum concentrations, the number of catalytic cycles (or turnover number) undergone by the ruthenium complex over the complete course of the photochemical reaction is as high as 1.1 × 10⁴.

Spectrofluorometric and laser flash photolysis techniques were used to study the primary photochemical reactions involving the excited state of the ruthenium complex as well as the photochemically generated species Ru(bpy)₃³⁺ and Ru(bpy)₃⁺. It is proposed that at pH 14 a sequence of reactions leading to O₂ photoreduction by electrons from semicarbazide takes place, with the concomitant formation of H₂O₂; the excited state of Ru(bpy)₃²⁺ appears to react via oxidative quenching by oxygen rather than via reductive quenching by semicarbazide. At neutral pH, in contrast, there is no H₂O₂ formation owing to the fact that semicarbazide is unable to reduce (Ru(bpy)₃³⁺ to Ru(bpy)₃²⁺, although the photoexcited ruthenium complex is quenched equally by oxygen.     

Cinetique et mecanisme de la reaction de prototropie des composes propargyliques alleniques et propynyliques portant un heteroatome (colonne vb et vib)

A detailed kinetic study of the prototropic rearrangement of the system RMCH₂CCH?RMCHCCH₂?RMCCCH₃ where M = NR, O, Se is presented. using deuterated substrates the nature of the reactive intermediates and, in the case of M = S, the activation energy-reaction profile are established.