Síntesis de catalizadores metal-carbenos N-heterocíclicos (NHC) y evaluación de su actividad catalítica en condiciones ambientalmente sostenibles

Abstract

The optimization of chemical reactions using catalysts allows to reduce reaction times and increase reaction yields. Homogeneous mesoionic NHC metal-carbene catalysts usually show high selectivity, improved activity and better stability compared to more classical analogous systems using organophosphine ligands. The main negative impact in the synthesis of catalysts is the use of organic solvents, so the use of deep eutectic solvents (DESs) has been proposed, which usually consist of two or three compounds; a quaternary ammonium salt complexed with a hydrogen donor compound or a metal salt. In this work, the synthesis of a mesoionic NHC metal-carbene catalyst by a series of "click chemistry" reactions, methylation, and complexation reactions with a transition metal by traditional and DES routes were proposed. The obtained compounds were characterized by infrared, magnetic resonance and melting points. And the catalytic activity of the metal-carbene-NHC obtained in Biginelli reactions was evaluated. These processes were compared in terms of reaction yields. The complexation of the catalyst was favored using DES, although in click chemistry and methylation the yield was lower than by the traditional route. To evaluate its catalytic activity, it is necessary to continue testing with different reactions.