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102. Advantages in supporting chiral organocatalysts

Author

GIACALONE, Francesco, GRUTTADAURIA, Michelangelo, NOTO, Renato, Giacalone, F, Gruttadauria, M, and Noto, R

Subjects
Organocatalysis, asymmetric synthesis, Settore CHIM/06 - Chimica Organica
Abstract

An overview on the advances in supporting organocatalysts for their use and recycle in the asymmetric synthesis is presented, focusing on the main approaches for the immobilization and highlighting those examples in which supported and unsupported version of the catalyst behave similarly and high level of recyclability have been obtained.

Published
2010

103. Recyclable organocatalysts

Author

GRUTTADAURIA, Michelangelo, GIACALONE, Francesco, NOTO, Renato, Gruttadauria, M, Giacalone, F, and Noto, R

Subjects
Organocatalysis, Settore CHIM/06 - Chimica Organica
Published
2010

105. Interazioni non covalenti tra esteri fosforici e nanotubi di carbonio a parete multipla

Author

MASSARO, Marina, CAPONETTI, Eugenio, NOTO, Renato, RIELA, Serena, SALADINO, Maria Luisa, Massaro, M, Caponetti, E, Noto, R, Riela, S, and Saladino, ML

Subjects
esteri fosforici, nanotubi di carbonio, interazioni non covalenti
Abstract

Fin dal 1991, quando Iijima li osservò per la prima volta, i nanotubi di carbonio (CNT) sono diventati oggetto d'interesse scientifico, in virtù delle loro proprietà fisiche, chimiche e meccaniche. Un impiego molto interessante riguarda l'aumento di stabilità di matrici polimeriche. I nanocompositi polimerici, in cui sono presenti percentuali molto basse di CNT (2.5%), presentano enormi miglioramenti nelle caratteristiche termomeccaniche, nella resistenza al calore e nella conduttività elettrica. C'è, però, un impedimento fondamentale a tutte le applicazioni che riguarda l'insolubilità intrinseca dei CNT nei solventi. La funzionalizzazione sia essa covalente che non è un espediente per ovviare a tale problematica. In questa comunicazione presentiamo dati preliminari di funzionalizzazione non covalente, tramite esteri fosforici, di nanotubi di carbonio a parete multipla (MWCNT) con potenziale applicazione nella formazione di nanocompositi polimerici.

Published
2010

108. Geminal Ionic Liquids: A Combined Approach to Investigate their Tridimensional Structure

Author

D'ANNA, Francesca, FERRANTE, Francesco, NOTO, Renato, D'Anna, F, Ferrante, F, and Noto, R

Subjects
ionic liquids, molecular dynamics, nmr spectroscopy, Settore CHIM/06 - Chimica Organica, Settore CHIM/02 - Chimica Fisica
Abstract

Different investigations, such as 1D and 2D NMR spectroscopy, resonance light scattering spectroscopy and molecular dynamics simulations, have been jointly used to achieve a deeper understanding of the degree of structural order in two geminal ionic liquids. In particular, 3,3’-di-n-butyl-1,1’-(1,3- phenylenedimethylene)diimidazolium and 3,3’-di-n-butyl-1,1’-(1,4-phenylenedimethylene) diimidazolium bis- ACHTUNGTRENUNG[bis(trifluoromethanesulfonyl)imide] have been studied. These geminal ionic liquids were chosen because of the presence of both a rigid phenylenedimethylene link between two imidazolium rings, which should give a high degree of order to the solvent system, and the different shapes of the two cations of the isomers, which could induce different properties and packing in the liquid state. Data collected here show that the two geminal ionic liquids are characterised by a different degree of structural order that induces, for example, a different sensitivity of the two solvent systems to temperature changes or to the presence of a co-solvent such as methanol.

Published
2009

109. New proline derivatives as recyclable catalysts for aldol reaction

Author

GRUTTADAURIA, Michelangelo, GIACALONE, Francesco, AGRIGENTO, Paola, SALVO, Anna Maria Pia, LO MEO, Paolo Maria Giuseppe, RIELA, Serena, NOTO, Renato, Gruttadauria, M, Giacalone, F, Agrigento, P, Salvo, AMP, Lo Meo, PMG, Riela, S, and Noto, R

Subjects
Catalysis, Organocatalysis, Aldol Reaction
Published
2009

123. Study of aromatic nucleophilic substitution with amines on nitrothiophenes in RTILs: are the different effects on the behavior of para-like and orto-like isomers on going from conventional solvents to RTILs related to solvation effects?

Author

D'ANNA, Francesca, FRENNA, Vincenzo, NOTO, Renato, PACE, Vitalba, SPINELLI D., D'ANNA F, FRENNA V, NOTO R, PACE V, and SPINELLI D

Subjects
ionic liquids, nucleophilic aromatic substitution, amines, Settore CHIM/06 - Chimica Organica
Abstract

The kinetics of the nucleophilic aromatic substitution of some 2-L-5-nitrothiophenes (para-like isomers) with three different amines (pyrrolidine, piperidine, and morpholine) were studied in three roomtemperature ionic liquids ([bmim][BF4], [bmim][PF6], and [bm2im][BF4], where bmim ) 1-butyl-3- methylimidazolium and bm2im ) 1-butyl-2,3-dimethylimidazolium). To calculate thermodynamic parameters, a useful instrument to gain information concerning reagent-solvent interactions, the reaction was carried out over the temperature range 293-313 K. The reaction occurs faster in ionic liquids than in conventional solvents (methanol, benzene), a dependence of rate constants on amine concentration similar to that observed in methanol, suggesting a parallel behavior. The above reaction also was studied with 2-bromo-3-nitrothiophene, an ortho-like derivative able to give peculiar intramolecular interactions in the transition state, which are strongly affected by the reaction medium.

Published
2006

128. Cyclodextrins: heterocyclic molecules able to perform chiral recognition (Part II)

Author

D'ANNA, Francesca, LO MEO, Paolo Maria Giuseppe, NOTO, Renato, RIELA, Serena, D'ANNA F, LO MEO P, NOTO R, and RIELA S

Subjects
cyclodextrin, pharmaceuticals and natural products, chiral selector
Abstract

The present paper collects the most significant advances appeared since late 1998 up to June 2005 in the field of applications of natural and modified cyclodextrins as chiral selectors, with particular regard for pharmaceuticals and natural products.

Published
2006

136. Spectrophotometric study on the thermodynamics of binding of α- and β-cyclodextrin towards some p-nitrobenzene derivatives

Author

LO MEO, Paolo Maria Giuseppe, D'ANNA, Francesca, RIELA, Serena, GRUTTADAURIA, Michelangelo, NOTO, Renato, Lo Meo, P, D'Anna, F, Riela, S, Gruttadauria, M, and Noto, R

Subjects
cyclodextrin, Settore CHIM/06 - Chimica Organica
Abstract

Binding properties of native alpha- and beta-cyclodextrin towards some nitrobenzene derivatives have been studied by means of UV-vis spectrophotometry. The former host is able to form complexes having 1 : 1 and 1 : 2 stoichiometric ratios with these guests, while only 1 : 1 complexes are detected with the latter host. A careful analysis of the thermodynamic parameters for complexation equilibria, under the perspective of the enthalpy-entropy compensation effect, reveals that binding abilities of the two different hosts are subject to different features.

Published
2004

140. Supported ionic liquid asymmetric cathalysis. A new method for chiral catalyst recycling

Author

GRUTTADAURIA, Michelangelo, RIELA, Serena, LO MEO, Paolo Maria Giuseppe, D'ANNA, Francesca, NOTO, Renato, GRUTTADAURIA, M, RIELA, S, LO MEO, PM, D'ANNA, F, and NOTO, R

Subjects
aldol reaction, Settore CHIM/06 - Chimica Organica, organocatalysi, ionic liquid
Abstract

A new method for chiral catalysts recycling, based on the supported ionic liquid asymmetric catalysis concept, has been developed. This concept involves the treatment of a monolayer of covalently attached ionic liquid on the surface of silica gel with additional ionic liquid. These layers serve as the reaction phase in which the homogeneous chiral catalyst is dissolved. As first application of this concept the L-proline-catalyzed aldol reaction has been carried out. Good yields and ee values, comparable with those obtained under homogeneous conditions have been obtained. Moreover, this material shows high regenerability.

Published
2004

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