Search results for "Concert"
showing 10 items of 67 documents
Diels-Alder Reactions of 2-Azabutadienes with Aldehydes: Ab Initio and Density Functional Theoretical Study of the Reaction Mechanism, Regioselectivi…
1997
The Diels−Alder reaction of 2-azabutadiene with aldehydes has been studied using high level ab initio molecular orbital and density functional methods. Multiconfigurational calculations were carried out on the concerted and stepwise mechanisms. At the CASPT2F/6-31G*//CASSCF/6-31G* level of theory, the [π4s + π2s]-cycloaddition of 2-azabutadiene with formaldehyde is predicted to be a concerted reaction, in good agreement with the experimental evidence. The regio- and stereoselectivity of the reaction was studied at the HF/6-31G*, MP2/6-31G*, and Becke3LYP/6-31G* levels of theory. The density functional calculations appears to give a good description of the basic features of the reaction. The…
A DFT Study of the Molecular Mechanisms of the Diels−Alder Reaction between Cyclopentadiene and 3-Phenyl-1-(2-pyridyl)-2-propen-1-one − Role of the Z…
2002
The molecular mechanism of the Diels−Alder reaction between cyclopentadiene (1) and 3-phenyl-1-(2-pyridyl)-2-propen-1-one (2) in the absence and in the presence of a Zn2+ Lewis acid catalyst has been studied by quantum mechanical calculations at the B3LYP/6-31G* level of theory. A continuum model was selected to represent the effects of the water as solvent. For the uncatalyzed process, two channels, endo and exo, were characterized, and the mechanism corresponded to an asynchronous concerted reaction associated with a [4+2] process. The presence of a Lewis acid catalyst changed the mechanism drastically, the reaction taking place by a polar stepwise mechanism. In the first step, a C−C sigm…
Understanding the Nature of the Molecular Mechanisms Associated with the Competitive Lewis Acid Catalyzed[4+2] and[4+3] Cycloadditions between Arylid…
2004
The molecular mechanisms of the reactions between aryliden-5(4H)-oxazolone 1, and cyclopentadiene (Cp), in presence of Lewis acid (LA) catalyst to obtain the corresponding [4+2] and [4+3] cycloadducts are examined through density functional theory (DFT) calculations at the B3LYP/6-31G* level. The activation effect of LA catalyst can be reached by two ways, that is, interaction of LA either with carbonyl or carboxyl oxygen atoms of 1 to render [4+2] or [4+3] cycloadducts. The endo and exo [4+2] cycloadducts are formed through a highly asynchronous concerted mechanism associated to a Michael-type addition of Cp to the beta-conjugated position of alpha,beta-unsaturated carbonyl framework of 1.…
Z dziejów muzyki w kościele pielgrzymkowym pw. św. Katarzyny Aleksandryjskiej w Starym Wielisławiu
2018
The biginnings of musical culture in Stary Wielisław are connected to the parish church of St. Catherine of Alexandria. For centures pilgrims made their wayto the place singing German language hymns. Liturgical customs in Stary Wielisław had a specific character (sung rosary) and certain patterns that had evolved over time (processions). A brass band that accompanied the pilgrims played an important role in them. The traditions of church music were cultivated thanks to the efforts of the local organists as wel as the vocal and instrumental group that was under their direction and whose beginnings reach back to the 17th century. It was one of greatest and best ensembles in the Kłodzko region…
Évaluation, concertation, décision : quelle régulation pour le système éducatif ? Le cas de l'enseignement primaire genevois
2011
Cet article tente de tisser quelques liens entre les notions de science, d'expertise et de décision démocratique en s'inscrivant ainsi dans la problématique développée par Weber (2003) lorsqu'il pose la question du sens de la science dans sa leçon " La profession et la vocation de savant ". Il y adopte la réponse donnée par Tolstoï : " Elle n'a pas de sens parce qu'elle ne peut répondre à la seule question qui importe pour nous, laquelle est de savoir ce que nous devons faire et comment nous devons vivre " (page 90). Sans avoir la prétention d'apporter la contradiction à la réponse de Tolstoï, notre ambition consiste à montrer qu'il a été possible, dans le cadre de l'évaluation de l'enseign…
DALLA CONCERTAZIONE ALL'EDUCAZIONE AMBIENTALE. RIFLESSIONI A MARGINE DELLE 4° JOURNEES REGIONALES DE LA PEDAGOGIE DE L'EAU
2010
Theoretical study of 1,3-dipolar cycloaddition reactions with inverse electron demand - A DFT study of the lewis acid catalyst and solvent effects in…
2000
The molecular mechanism for the inverse electron demand 1,3-dipolar cycloaddition of nitrones with vinyl ethers has been characterized using density functional theory methods with the B3LYP functional and the 6−31G* basis set. Relative rates, regioselectivity, endo/exo stereoselectivity, Lewis acid catalyst and solvent effects are analyzed and discussed. Four reactive channels associated with the formation of two pairs of diasteromeric regioisomers have been characterized. Analysis of the geometries of the corresponding transition structures shows that the reaction in the gas phase takes place by an asynchronous concerted mechanism. These 1,3-dipolar cycloadditions present a large ortho reg…
Vienna Parigi Berlino, tre luoghi dell'anima: recensione del libro "I papillons di Brahms" di Piero Violante, Palermo, Sellerio 2009.
2009
Il libro "I papillons di Brahms" di Piero Violante, Palermo, Sellerio 2009, raccoglie i saggi che il suddetto ha scritto, su invito di Paolo Emilio Carapezza, presidente degli Amici del Teatro Massimo, per presentare gli spettacoli in detto teatro rappresentati tra il 1998 e il 2008, nonché alcuni altri saggi dello stesso autore, professore di Sociologia della musica nell'Università di Palermo.
Bach fra le stelle
2014
Il testo costituisce la postfazione del volume di Ramin Bahrami "Il suono dell'Occidente. Le opere musicali che hanno fatto la nostra civiltà" (Mondadori 2014) e prende le mosse dal concetto di "Enciclopedia" per tracciare una riflessione storico-musicologica sulle 14 composizioni che Ramin Bahrami ssume quali imprescindibili punti di riferimento per una visione d'insieme della cultura musicale occidentale: da Monteverdi fino a Schoenberg, passando per Vivaldi, Bach, Wagner, Verdi, Mahler, Rakhmaninov e Stravnsky.
Le concerto pour orchestre de Béla Bartok : analyse des 2e et 3e mouvements
2007
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