Solvent effects on molecular reaction media. Nucleophilic ability and acid catalyst behavior of Protic Ionic Liquids

P. M. MANCINI, M. V. BRAVO, AND C.G. ADAM

Dalian, China

Conferencia; 2nd Asia Pacific Conference on Ionic Liquids and Green Processes.; 2010

Molecular solvents are the usual media where physical and chemical processes take place. In the last decade, the researches have been dedicating their work to the use a novel solvent for developing clean technologies. The ionic liquids (ILs) might offer process advantages over molecular solvents; these solvents are denominated “Green” and are used in the development of new synthesis routes. Recently we have demonstrated how the addition of small amounts of a protic ionic liquid (PIL) to a pure molecular solvent modifies the microscopic characteristics of a reaction medium1. In this sense we have confirmed that in the presence of a carbonyl compound, the IL can act as both Brönsted acid and/or nucleophile.The corresponding imine with good yields was observed. Complementarily, in this work we have studied the behaviour of the presence of a PIL in a molecular reaction media of two types of different reactive processes. On one hand the possibility of enamine formation in a reaction media constitute by a molecular solvent and small amounts of PLI was evaluated. We have studied the reaction between a carbonyl compound and the nucleophile generated in the reaction media. For this purpose the reaction media was contituted by a molecular solvent, acetonitrile (AcN) and PILs such as nitrate or acetate pyrrolidonium. The carbonyls compound selected were cyclohexanone, 2-methylcyclohexanone and 2-cyclohexen-1-one. On the other hand the influence of small amount of this IL in the transesterification reaction was discussed. In this direction we selected p-Nitrophenyl Acetate and the same ILs. We are confirming the formation of nitrophenol as a product with a good yield. In both cases we can demonstrate that the presence of PIL acting as a Brönsted acid catalyst or even more, as a potential nucleophile, changes dramatically the reaction way.