Palladium(0) allylic alkylation in a two-phase system or with a supported aqueous phase catalyst

The reaction of allylic carbonates with various acyclic and cyclic carbonucleophiles is catalyzed by the system Pd(OAc)₂ and P(C₆H₄-m-SO₃Na)₃ (or tppts) in a two-phase liquid medium H₂O-nitrile, the activity of the catalyst depending mainly on the nature of the nitrile, the temperature of the reaction and the ratio palladium/tppts. The same system Pd(OAc)₂ and P(C₆H₄-m-SO₃Na)₃ supported on silica catalyzes also this reaction. The formation of the active palladium species in the two cases is followed by

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NMR spectroscopy and discussed.     

Oxidative polymerization and partial dechlorination of 2,4,6‐trichlorophenol by a mixture of peroxidase isozymes from Vaccinium myrtillus

Plant peroxidases (EC 1.11.1.7) catalyze the oxidation of phenolic pollutants in the presence of hydrogen peroxide. In the present study, extracellular peroxidases from Vaccinium myrtillus cell suspension cultures (VMP) were evaluated for their ability to polymerize 2,4,6‐trichlorophenol (TCP), a ubiquitous environmental contaminant. The effect of pH, temperature, reaction time, enzyme amount and initial pollutant concentration on the treatment efficiency was investigated in order to optimize the reaction conditions for TCP removal. An appreciable removal efficiency and a partial dehalogenation of TCP was observed over a wide range of initial pollutant concentrations (0.1–20 mmol dm^?3) and reaction conditions suggesting that VMP could be useful for potential decontamination applications. The use of polyethylene glycol in the reaction mixture allowed a reduction of the catalyst requirements needed to obtain well defined extents of TCP removal. © 2001 Society of Chemical Industry     

Physico-Chemical Features and Catalytic Activity of Sulfated Zirconia Prepared by Sol–Gel Method. The Role of the Solvent Evaporation Step

ZrO₂–SO₄ powders have been prepared by following a single-step sol–gel preparative route using zirconium propoxide as the starting compound. Sulfuric acid was employed both as the sulfating agent and as the catalyst of the polycondensation reaction in the gel formation. Two different series of dried precursors were obtained by either evaporating the solvent in an oven at 100°C (xerogels) or in supercritical conditions (aerogels). All the samples were calcined at three temperatures (470, 550, and 630°C) for the same time length (5 h). The powders were characterized for phase composition–crystallinity, surface area–porosity, sulfur content and surface state (XPS). The catalytic activity of the calcined samples was tested in the isomerization of n-butane in a continuous system at 150°C in absence of H₂ and 250°C in presence of H₂. The role played by the conditions of the solvent elimination, at the end of the sol–gel reaction, in affecting the physico-chemical and catalytic properties of the powders is discussed.     

Linguistic intergroup bias: Differential expectancies or in-group protection?

The linguistic intergroup bias describes the tendency to communicate positive in-group and negative out-group behaviors more abstractly than negative in-group and positive out-group behaviors. This article investigated whether this bias is driven by differential expectancies or by in-group protective motives. In Exp 1, northern and southern Italian participants (N?=?151) described positive and negative behaviors of northern or southern protagonists that were either congruent or incongruent with stereotypic expectancies. Regardless of valence, expectancy-congruent behaviors were described more abstractly than incongruent ones. Exp 2 (N?=?40) showed that language is used in an equally biased fashion for individuals as previously demonstrated for groups. Exp 3 (N?=?192) induced expectancies experimentally and found greater abstraction for expectancy-congruent behaviors regardless of valence. All experiments confirmed the differential expectancy approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical Properties of Highly Porous Super Liquid‐Repellent Surfaces

Surfaces with self‐cleaning properties are desirable for many applications. Conceptually, super liquid‐repellent surfaces are required to be highly porous on the nano‐ or micrometer scale, which inherently makes them mechanically weak. Optimizing the balance of mechanical strength and liquid repellency is a core aspect toward applications. However, quantitative mechanical testing of porous, super liquid‐repellent surfaces is challenging due to their high surface roughness at different length scales and low stress tolerance. For this reason, mechanical testing is often performed qualitatively. Here, the mechanical responses of soot‐templated super liquid‐repellent surfaces are studied qualitatively by pencil and finger scratching and quantitatively by atomic force microscopy, colloidal probe force measurements, and nanoindentation. In particular, colloidal probe force measurements cover the relevant force and length scales. The effective elastic modulus, the plastic work W_plastic and the effective adhesive work W_adhesive are quantified. By combining quantitative information from force measurements with measurements of surface wetting properties, it is shown that mechanical strength can be balanced against low wettability by tuning the reaction parameters.