Access to original spirocyclic derivatives via inter- or intramolecular reaction mediated by manganese(III) acetate

An easily reproducible protocol allowing inter- or intramolecular spirocyclization on β-dicarbonyl structures is described. This methodology could afford a wide variety of spirocyclic pharmacophores. As examples, highly substituted spirobenzophenanthridin-6(5H)-ones and spirolactones were synthesized. These scaffolds could be used for the design of many compounds exhibiting biological activities.     

Préparation,caractérisation et réactivité de l’acide 1-vanado-11-molybdo-phosphorique supporté sur des matériaux silicatés mésoporeux dans l’oxydation du propène

The H₄PMo₁₁VO₄₀ heteropolyacid (HPA) was supported at 30 wt.% by the dry impregnation method on HMS, CMI-1 and SBA-15 mesoporous materials. The state of the HPA and those of the supports were examined by nitrogen physisorption, X-ray diffraction, (DR) FT–IR and X-ray photoelectron spectroscopies, thermal analysis (TG–ATD) and scanning electron microscopy (SEM). The effect of support on the catalytic behavior of H₄PMo₁₁VO₄₀ was studied in the propene oxidation at 350 °C. It was shown that the presence of H₄PMo₁1VO₄₀, modifies the textural properties of mesoporous materials (decrease of surface area) without destroying their structure. The interaction support–heteropolyacid leads to the formation of (SiOH²⁺)(H₃PMo₁₁VO₄₀^?) surface species more stable than H₄PMo₁₁VO₄₀ species and that appear to be the active sites in the propene oxidation.     

Bis(crown ether) and Azobenzocrown Derivatives of Calix[4]arene. A Review of Structural Information from Crystallographic and Modelling Studies

The association within one molecule ofcalix[4]arene and crown ether moieties leads toligands with new complexing properties. In particular,calix[4]arene bis(crown-6) and some of itsderivatives have been shown to be highly selectiveextractants for caesium ions. This review presents thebackground of the study and the results of crystalstructure determinations and molecular modellingcalculations performed during the investigation of twomolecular families, the bis(crown ether) and theazobenzocrown derivatives of calix[4]arene.     

Viscoelastic properties and interfacial tension of polystyrene–polyethylene blends

The linear viscoelastic properties of polystyrene polyethylene (PS/PE) blends have been investigated in the molten state. For concentrations of the dispersed phase equal to 30 vol %, the blends exhibited a droplet‐matrix morphology with a volume‐average diameter of 5.5 μm for a 70/30 PS/PE blend at 200 °C and 14.7 μm for a 30/70 PS/PE blend at 230 °C. Enhanced elasticity (G′) for both blends, in the terminal zone, compared to the modulus of the matrix (PS and PE, respectively) was observed. This is related to the deformation of the droplets in the matrix phase and hence to the interfacial forces between the blend components. The results for these uncompatibilized blends are shown to be in agreement with the predictions of the emulsion model of Palierne. These predictions were used to obtain the interfacial tension between PS and PE, which was found to be between 2 and 5 mN/m at 200 °C and 4 ± 1 mN/m at 230 °C. Independent interfacial tension measurements using the breaking‐thread method resulted in a value of 4.7 mN/m and 4.1 mN/m at 200 °C and 230 °C for the respective blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1359–1368, 2000     

Synthesis and characterization of new highly permeable polyamideimides from dianhydride monomers containing amide functions: An application to the purification of a fuel octane enhancer (ETBE) by pervaporation

Six polyamideimides (PAI) were synthesized from six dianhydride monomers containing amide functions. The dianhydride monomers were obtained from the reaction of trimellitic anhydride chloride with six aromatic diamines—1,4‐phenylenediamine, 2,2‐bis(4‐aminophenyl) propane, 4,4′‐oxydianiline, 4,4′‐methylenedianiline, 1,1‐bis(4‐aminophenyl)cyclohexane, and bis(4‐aminophenyl)sulfone—by a low‐temperature condensation with yields ranging from 35 to 98% depending on the monomer solubility in organic media. The monomers were characterized by Fourier transform infrared (FTIR) and ¹H NMR. In accordance with a synthesis scheme implying the reaction of a macrodiisocyanate with dianhydride monomers containing amide functions, six PAIs with a highly flexible soft block (polytetramethylene glycol PTMG 650) were synthesized with inherent viscosities ranging from 0.38 to 1.3 dL/g. Their characterization by FTIR and ¹H NMR fully confirmed their chemical structure. The strong physical crosslinking provided by polar hard blocks containing up to eight aromatic rings enabled the casting of PAI films that were very tough in the dry state and could withstand exposure to rather strong solvating media (e.g., ethers, alcohols, and chlorinated solvents). First experiments showed these materials could be good candidates for membrane‐separation applications. They revealed interesting features for the separation of organic aprotic–protic mixtures as shown by the first results obtained for the purification of a fuel octane enhancer (ethyl‐tert‐butyl ether) used in the European Community. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 614–630, 2000     

PM3 semi-empirical study of stereoelectronic effects in the Baeyer-Villiger reaction

The Baeyer-Villiger reaction of polymethoxybenzaldehydes with peroxysuccinic acid (PSA) is studied theoretically. The semi-empirical SCF-MO/PM3 method has been used to study the reaction and to calculate the energy profiles. In addition, heat of formation computations and bond order analyses of the transition species along the reaction coordinates have been performed and are interpreted qualitatively in terms of electron flow through the system during aryl migration. Our results support the hypothesis that the second step is a concerted reaction. Our data support a definite effect of the substituent on the aryl migration. The theoretical predictions are in good agreement with experimental results.