An alkylzinc bromide and a lithium alkyldibromozincate containing tris(organosilyl)methyl groups

The lithium reagent (3) reacts with a molar equivalent of anhydrous zinc bromide to give the dimeric compound (2a), in which zinc is four-coordinate. The product from a similar reaction with Li{C(SiMe₃)₂(SiMe₂NPhMe)} is the lithium zincate [Li(THF)₂(μ-Br)₂Zn{C(SiMe₃)₂(SiMe₂NPhMe)}] (4), in which the zinc is only three-coordinate. The crystal structures of 2a and 4 have been determined.     

Silica/Polyamide Nanocomposite Synthesis via an Original Double Emulsification Process in Miniemulsion

Summary: A new method for the encapsulation of inorganic charges by an organic polymer by a reactive double emulsification process is proposed. This work is especially novel since it is highly unusual to encounter polymerization reactions in such a double emulsification process. Silica was first synthesized in cyclohexane using a sol–gel process in an inverse microemulsion in the presence of a non‐ionic surfactant (nonylphenyl ether polyoxyethylene), tetraethoxysilane, and concentrated ammonia. The coupling agent, 3‐aminopropyl triethoxysilane, was then grafted onto the surface of the silica nanoparticles. In a third step, direct miniemulsions were prepared from the microemulsion containing the functionalized silica nanoparticles. The miniemulsions were prepared using sodium dodecylsulfate as the surfactant and cetyl alcohol as the costabilizer. Finally, an interfacial polycondensation occurred between a diamine added to the external phase and sebacoyl chloride in solution in the dispersed phase. The formation of polyamide latexes was proven using infrared spectroscopy, and observation of the nanocomposites by transmission electron microscopy showed mean diameters of 100 nm.

TEM micrograph of silica/polyamide nanocomposite particles     

Quantitative on-line preconcentration-liquid chromatography coupled with tandem mass spectrometry method for the determination of pharmaceutical compounds in water

One of the current environmental issues concerns the presence and fate of pharmaceuticals in water bodies as these compounds may represent a potential environmental problem. The characterization of pharmaceutical contamination requires powerful analytical method able to quantify these pollutants at very low concentration (few ng L⁻¹).     

Copolymerization of novel reactive fluorinated acrylic monomers with styrene: reactivity ratio determination

The radical copolymerization of three polymerizable surfactants with styrene was investigated by NMR spectroscopy to assess their compositions. The reactivity ratios of these monomers were calculated according to the methods of Fineman–Ross and Kelen–Tüdos. Consequently, Q and e values were deduced by the Alfrey and Price method. The results indicated the positive effect of the fluorine chain on the reactivity of monomers bearing a long spacer between the ammonium head and the acrylic function. These monomers exhibit high e values which are in favor of an intramolecular conformation of the surfactant where the ester carbonyl function of the polymerizable group interacts with the onium nitrogen atom via a compact six-sided structure.     

Synthesis and characterization of highly ordered mesoporous nanomaterials Al-MCM-41 and Al-SBA-15 from bentonite as efficient catalysts for the production of biodiesel MELA and EELA

Research on Chemical Intermediates - Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents...     

Comparative morphology of early stages of two Mediterranean Sarcophaga Meigen, 1826 (Diptera; Sarcophagidae) and a review of the feeding habits of Palaearctic species

The third instar larva of Sarcophaga hirticrus Pandellé, 1896 and Sarcophaga javita (Peris, González-Mora and Mingo, 1998) are described and figured for the first. The use of scanning electron microscopy (SEM) has been demonstrated as an effective tool for determining differences at the specific level, and is here applied. The two species are distinguished from other Sarcophaga spp. and the principal diagnostic character states are illustrated and discussed. Comparative information on immature stages morphology of the described Palaearctic Sarcophaga species and its feeding habits are compiled and provided in a tabulated form.