Search results for "Ash"
showing 10 items of 1718 documents
DEEP EUTECTIC SOLVENTS E LIQUIDI IONICI: SOLVENTI PER LO SVILUPPO DI PROCESSI ECO-COMPATIBILI
2020
L’obiettivo di questi tre anni di Dottorato è stato lo studio e l’utilizzo nuovi solventi di reazione in grado di sostituire i solventi organici classici. In particolare sono stati studiati i Deep Eutectic Solvent (DES) e le miscele di Liquidi Ionici (IL). I DES sono stati utilizzati come solventi per lo studio di reazioni organiche, usate per la formazione di nuovi legami C-C. Nello specifico sono state studiate la reazione di Diels-Alder, e diverse reazioni di coupling C-C catalizzate da Pd. In seguito, i DES sono stati utilizzati per la formazione di nuovi gel supramolecolari, chiamati eutectogel. Questi gel sono stati formati usando come gelator amminoacidi naturali, consentendo quindi …
Sustainable Approach to Waste-Minimized Sonogashira Cross-Coupling Reaction Based on Recoverable/Reusable Heterogeneous Catalytic/Base System and Ace…
2016
In this contribution, we present a chemically efficient and sustainable protocol for the palladium-catalyzed copper-free Sonogashira cross-coupling reaction, based on the use of a heterogeneous catalytic system. This consists in the combination of a palladium catalyst on highly cross-linked thiazolidine network on silica and a polystyrene-supported base. The solid catalyst/base system acts as a palladium scavenger avoiding leaching of the metal and consequent product contamination. The reaction can be conducted in safe and easily recoverable acetonitrile/water azeotrope as reaction medium. This proved to be an efficient greener alternative to the classic toxic aprotic media commonly used in…
ChemInform Abstract: Recyclable Heterogeneous Palladium Catalysts in Pure Water: Sustainable Developments in Suzuki, Heck, Sonogashira and Tsuji-Tros…
2010
This review summarizes the progress made essentially these last ten years on heterogeneous palladium catalysis in pure water. The work covers four important palladium-catalyzed transformations for carbon-carbon bond formation: Suzuki, Heck, Sonogashira and Tsuji-Trost reactions. The discussion focuses on the efficiency and reusability of the heterogeneous catalysts as well as on the experimental conditions from a sustainable chemistry point of view. The review is introduced by a discussion on mechanistic aspects inherent to heterogeneous catalysis.
Ultra-Low Catalyst Loading as a Concept in Economical and Sustainable Modern Chemistry: The Contribution of Ferrocenylpolyphosphane Ligands
2007
The challenge of sustainability in modern chemistry will be met with new technologies and processes provided significant progress is made in several key research areas, such as the expansion of chemistry from renewable feedstock, the design of environmentally benign chemicals and solvents, the minimization of depletive resources, and the development of high-performance catalysis. In this prospect, ligand chemistry is a pivotal science that links modern-organic,-inorganic, -organometallic, and -coordination chemistry through a vast number of valuable applications, precisely associated to catalysis. We review in this article our recent work on catalysis promoted by original ferrocenyl tetra-,…
Uncommon perspectives in palladium- and copper-catalysed arylation and heteroarylation of terminal alkynes following Heck or Sonogashira protocols: I…
2013
Abstract Conjugated alkynes are recurring building blocks in natural products and in a wide range of important compounds, such as pharmaceuticals, agrochemicals, or molecular materials. The palladium-catalysed cross-coupling reaction between the sp 2 -hybridized carbon atoms of aryl, heteroaryl, and vinyl halides with the sp -hybridized carbon atoms of terminal alkynes is one of the most important developments in the field of alkyne chemistry over the past 50 years. Room for improvement still exists in these important reactions of direct arylation of terminal alkynes. In this prospect, the present authors have developed several strategies aiming at improving the reactivity, the selectivity,…
Recyclable heterogeneous palladium catalysts in pure water: sustainable developments in Suzuki, Heck, Sonogashira and Tsuji-Trost reactions
2010
This review summarizes the progress made essentially these last ten years on heterogeneous palladium catalysis in pure water. The work covers four important palladium-catalyzed transformations for carbon-carbon bond formation: Suzuki, Heck, Sonogashira and Tsuji-Trost reactions. The discussion focuses on the efficiency and reusability of the heterogeneous catalysts as well as on the experimental conditions from a sustainable chemistry point of view. The review is introduced by a discussion on mechanistic aspects inherent to heterogeneous catalysis.
Trasparenza del mercato, tutela del consumatore e green washing
2022
Il saggio propone una riflessione sulla politiche di trasparenza del mercato strumentali all’ obiettivo della sostenibilità ambientale. Nella prospettiva del mercato unico sostenibile un ruolo fondamentale viene attribuito ai c.d green claims, laddove alto è il rischio che la sostenibilità divenga per le aziende una semplice strategia di marketing. Il fenomeno, noto come green washing, si pone in una prospettiva peculiare rispetto alla pubblicità ingannevole, pone domande diverse e reclama risposte diverse. Duplice la linea di intervento seguita dal legislatore euro unitario, da una parte la tutela dalle pratiche commerciali scorrette, dall’altra, quella dell’obbligo di conformità al contra…
La situation de l’artisanat verrier à Augustodunum dans le contexte des découvertes effectuées en Gaule
2007
Il est rappelé d’abord que les cartes de répartition des ateliers de verriers en Gaule, aux premiers siècles de notre ère, écartent de nombreux sites de transformation de verre brut importé du Proche-Orient, au motif qu’on n’y a pas retrouvé de déchets exploitables d’un point de vue typologique. Mais les traces d’activités verrières de cette époque semblent bien plus nombreuses que ne le montrent ces cartes, à l’instar de ce qu’on observe à Autun.Malgré le caractère bien incomplet de nos connaissances sur la répartition des ateliers de verriers anciens de Gaule romaine, cette répartition constitue dès à présent un solide argument en faveur de la prépondérance pour le verre d’un commerce de …
Creating Value – From Corporate Governance to Total Shareholders Return. An Overview
2016
Abstract The term “value” can be interpreted in a subjective way, depending about what we refer at. Usually the firm's value is related to the financial performance: profitability, cash flow, liquidity, solvability, etc. A corporation can create and in some cases reduce value for its stakeholders. Also, a corporation can create value for the stakeholders by simply creating jobs, paying taxes and help the population to improve their financial situation. The aim of the paper is to describe the process of value creation starting with corporate governance, continuing with stakeholders’ expectations and finishing with shareholders requests.
European leaders unmasked: Covid-19 communication strategy through Twitter
2020
[EN] The coronavirus disease Covid-19 (SARS-CoV-2) pandemic is exacting a huge toll on individuals, families, communities, and societies across the world. The study of public communication is a key aspect for slowing the spread of the virus and therefore reducing the death rate. This article analyses political leaders' crisis communication during the Covid-19 pandemic of the most affected European countries, Boris Johnson (United Kingdom), Emmanuel Macron (France), Pedro Sanchez (Spain) and Giuseppe Conte (Italy), in addition to Tedros Adhanom as a representative of the World Health Organisation (WHO) and Ursula Von der Leyen President of the European Union (EU). The study focuses on the vi…