Estudos visando à preparação e utilização de líquidos iônicos, derivados do glicerol e de aminoácidos, como amino catalisadores

Abstract

In this work, we describe the synthesis of ionic liquids composed of quaternary ammonium salts derived from glycerol as a cation and amino acids as anions. Three different types of cations were synthetized: The cation type one the 3-(triethylammonium)propan-1.2-diol, the cation type two N-((1.3-dioxolan-4-yl) methyl)N,N,N-tri-ethylammonium and the cation type three 1,3-bis (tri-ethylammonium)propan2-ol. Ten compounds with characteristics of ionic liquid have been synthetized, five of them using the cation of type one and the others five using cation of type two. As anions have been used carboxylates of the respective amino acids: L-Valine, L-Leucine, LProline, L-tyrosine and L-cysteine. The three type of cation was prepared their respective ionic liquids do not however. The ionic liquids prepared were characterized by unusual structural determination methods (1H-NMR, 13C-NMR and IR) and the physicochemical characterizations like water contends, density, solution conductivity, melting point, glass transition, decomposition temperatures and qualitative solubility have been investigated. The ionic liquid [3-(tri-ethylammonium)propan-1,2-diol] [(S)-2-pyrrolidinecarboxylic acid salt] was used as amino catalyst on the Michael addition reaction between cyclohexanone and the trans β-nitrostyrene in acetonitrile. The Michael adduct was obtained in 49% yield with high stereoselectivity 10:1 ratio syn: anti. The enantioselectivity of the adducts formed approached a racemic mixture, which suggests the dissociation of ionic liquid in the solvent used.