|
Abstract
|
Pechmann condensation is a method for synthesis of coumarins which starts from a phenol and a carboxylic acid or ester containing a β-carbonyl group. The condensation is performed under acidic conditions and the mechanism involves an esterification/trans-esterification followed by attack of the activated carbonyl ortho to the oxygen in order to generate the new ring. This reaction is finalized with dehydration. Condensation reaction leading to coumarin and its derivatives was discovered by the German chemist, Hans von Pechmann. In this work the reaction is performed in presence of a novel ionic liquid bearing multi-HSO4 groups at ambient temperature and the corresponding coumarin derivatives with high to excellent yields in shorter reaction times are prepared. In this research the efficiency, generality and applicability of new nanosilica based ionic liquid NaHSO4 as heterogeneous and green catalyst for the synthesis of coumarin derivatives from the reaction of phenols and β-ketoesters and 1,3-diketones in water and ethanol (as co-solvent) with 50% V/V at room temperature are studied.
|