6 resultados para Mass Media.
em Universidade do Minho
Resumo:
Dissertação de mestrado em Ciências da Comunicação (área de especialização em Informação e Jornalismo)
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Dissertação de mestrado em Administração da Justiça
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Dissertação de mestrado em Ciências da Comunicação (área de especialização em Informação e Jornalismo)
Resumo:
Radical cyclization continues to be a central methodology for the preparation of natural products containing heterocyclic rings. Hence, some electrochemical results obtained by cyclic voltammetry and controlled-potential electrolysis in the study of electroreductive intramolecular cyclization of ethyl (2S, 3R)-2-bromo-3-propargyloxy-3-(2’,3’,4’,6’-tetra-O-acetyl-beta-D-glucopyranosyloxy) propanoate (1a), 2-bromo-3-allyloxy-3-(2’,3’,4’,6’-tetra-O-acetyl-beta-D-glucopyranosyloxy)propanoate (1b), 2-bromo-[1-(prop-2-yn-1-yloxy)propyl]benzene (1c) and [1-bromo-2-methoxy-2-(prop-2’-yn-1-yloxy)ethyl]benzene (1d) promoted by (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)nickel(I), [Ni(tmc)]+, electrogenerated at glassy carbon cathodes in ethanol and ethanol:water mixtures containing tetraalkylammonium salts, are presented. During controlled-potential electrolyses of solutions containing [Ni(tmc)]2+ and bromoalkoxylated compounds (1) catalytic reduction of the latter proceeds via one-electron cleavage of the carbon–bromine bond to form a radical intermediate that undergoes cyclization to afford the substituted tetrahydrofurans.
Resumo:
We investigated the reductive intramolecular cyclization of bromopropargyl ethers derivatives, catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane)nickel(I), [Ni(tmc)]+ as the catalysts in N,N,N-trimethyl-N-(2- hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide,[N1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim][NTf2] by cyclic voltammetry and controlled-potential electrolysis. The results show that the reaction leads to the formation of the expected cyclic compounds, which are important intermediates in the synthesis of natural products with possible biological activities.
Resumo:
Cidadania digital. Ativismo na net. Redes de cidadãos: Projeto 1: Interesses dos cidadãos e redes sociais. Movimentos sociais: Projeto 2: Movimentos sociais na rede; Mobilizaçao online: Manuel Castells. Ação política online. Media táticos (tactical media); Reflexão sobre os media táticos: Geert Lovink. Táticas dos media táticos. Ação direta virtual de massa (Mass Virtual Direct Action – MVDA). Desobediência civil eletrónica (Electronic Civil Desobedience - ECD). Guerras da (des)informação (Infowar).