Search results for "CATA"

Structural Motifs of Alkali Metal Superbases in Non‐coordinating Solvents

2020

Abstract Lochmann–Schlosser superbases (LSB) are a standard reagent in synthetic chemistry to achieve an exchange of a proton on an organic framework with an alkali metal cation, which in turn can be replaced by a wide range of electrophilic groups. In standard examples, the deprotonating reagent consists of an equimolar mixture of n‐butyllithium and potassium t‐butoxide. However, the nature of the reactive species could not be pinned down either for this composition or for similar mixtures with comparable high reactivity. Despite the poor solubility and the fierce reactivity, some insights into this mixture were achieved by some indirect results, comparison with chemically related systems,…

Polystyrene-supported organocatalysts for alfa-selenenylation and Michael reactions. A common post-modification approach for catalytic differentiation

2011

Three different resin-supported catalysts have been prepared by using the well established post-modification approach by means of thiol-ene coupling reaction. Two catalysts were tested for the first time in the asymmetric α-selenenylation of propanal, while the third catalyst was used in the Michael addition reaction. While the preliminary results are not encouraging in the case of supported Jørgensen’ catalyst, interesting data have been collected with both for the supported MacMillan and prolyl-prolinol catalysts. In fact, these catalysts displayed good activity and selectivity. A reversed enantioselectivity in the α-selenenylation was observed by changing the polarity of the solvent. Fin…

From covalently linked catalysts to "release and catch" catalytic systems

2014

Catalytic applications of TiO2

2021

Abstract The use of TiO2 as heterogeneous catalyst and/or active support for metals or other oxides is here reported. Many reactions of industrial relevance involve, in fact, titania-based catalysts, among them, NOx abatement, Fischer–Tropsch and water–gas shift, Deacon and Claus processes, hydrodesulfurizations and hydrogenations, selective reductions and selective oxidations. This chapter aims to discuss the main applications of TiO2, in its different forms, as effective support or catalyst for thermocatalytic and photo-thermocatalytic reactions, focusing on the role of its structural and physicochemical properties on the catalytic performance (activity, selectivity, stability).

Silica powder obtained by sol-gel method as a support of organometallic vanadium catalyst for ethylene polymerization

2004

Sol-gel technique was employed to obtain the silica-type powder, which after modification procedure was applied as asupport of organometallic catalytic system for ethylene polymerization. The powder product was synthesized using hydrolysis and condensation of TEOS, catalyzed by ammonia. Obtained material and a reference support (commercial silica Davisil) were characterized to determine their particle size distributions, BET surface area, pore volume and diameter. Gas-phase adsorption of vanadium catalyst on analyzed support materials as well as adsorption from the solution in hexane were carried out. Both carrier materials were thermally pretreated prior catalytic systems syntheses and the…

The Hexameric Resorcinarene Capsule as a Brønsted Acid Catalyst for the Synthesis of Bis(heteroaryl)methanes in a Nanoconfined Space

2019

Herein, we show that the hexameric resorcinarene capsule C is able to catalyze the formation of bis(heteroaryl)methanes by reaction between pyrroles or indoles and carbonyl compounds (α-ketoesters or aldehydes) in excellent yields and selectivity. Our results suggest that the capsule can play a double catalytic role as a H-bond catalyst, for the initial activation of the carbonyl substrate, and as a Bronsted acid catalyst, for the dehydration of the intermediate alcohol.

Supramolecular Organocatalysis in Water Mediated by Macrocyclic Compounds

2018

In the last decades many efforts have been devoted to design supramolecular organocatalysts able to work in water as the reaction medium. The use of water as solvent provides promising benefits with respect to environmental impact. In this context, macrocyclic compounds played a role of primary importance thanks to their ease of synthesis and their molecular recognition abilities toward the reactants. The aim of this review is to give an overview of the recent advances in the field of supramolecular organocatalysis in water, focusing the attention on calixarene and cyclodextrins derivatives. Calixarenes and cyclodextrins, thanks to their hydrophobic cavities, are able to host selectively th…

The Supranational Dimension in Max Weber’s Vision of Politics

2019

Max Weber analyzed politics from the perspective of Chancen for actors, and he never separated world politics from domestic politics. The “Westphalian balance” between great European powers shaped Weber’s views on international polity. However, he also regarded Western individualism, human rights, and parliamentary democracy as necessary qualities to possess in order to be recognized as a great power. This vision provided the basis for his wartime critique of the expansionist tendencies in German foreign policy and for his demand for the parliamentarization of German politics. After the end of World War I, Weber used Woodrow Wilson’s idea of the League of Nations as the basis for a proposal…

The commitment of the GISIO-SItI to contrast Healthcare- Associated Infections and the experience of the prevalence studies in Sicily

2018

Surveillance of Healthcare-Associated Infections (HAIs) is essential to improve the quality of health services. The aim of this paper is to report the commitment of the Italian Study Group of Hospital Hygiene (GISIO) of the Italian Society of Hygiene, Preventive Medicine and Public Health (SItI) describing some experiences to contrast HAIs and antimicrobial resistance. Particularly, the commitment to contrast HAIs in intensive care with the SPIN-UTI project - Italian Nosocomial Infections Surveillance in ICUs, and in surgery with the ISCHIA project - Infections of Surgical Site in Arthroplasty Interventions - were described. Furthermore, some activities conducted in Sicily using repeated pr…

Monitoraggio e percezione delle esperienze formative internazionali tra gli specializzandi italiani in igiene e medicina preventiva. Indagine condott…

2013

Introduzione Molti studi hanno dimostrato che le esperienze formative internazionali (International Health Electives - IHE) contribuiscono all'acquisizione di conoscenze e competenze fondamentali per i futuri professionisti in Sanità proprio attraverso l'opportunità di confronto fra sistemi sanitari e contesti socio-culturali differenti. Sebbene le IHE siano in crescita, non ci sono dati che riguardino quelle svolte dagli specializzandi italiani in Igiene. L'obiettivo dello studio è di raccogliere informazioni sulle loro pregresse esperienze formative internazionali e di comprendere motivazioni ed eventuali criticità relative alla decisione di effettuare una IHE. Materiali e metodi Gli spec…