Kf-Al₂O₃ Catalysed Synthesis of 3-Phenyl-2-Propenoic Acids in Dry Media Under Microwave Irradiation

Abstract

Malonic acid was condensed with several aryl – substituted aldehydes to the corresponding 3-phenyl-2-propenoic acids under microwave irradiation in solvent-free conditions on potassium fluoride impregnated alumina. Yields were dramatically improved in comparison with classical heating under the same conditions.

Microwave-Assisted Knoevenagel-Doebner Reaction: An Efficient Method for Naturally Occurring Phenolic Acids Synthesis

“…In order to develop an efficient and reproducible method for the synthesis of natural occurring PAs, microwave- assisted reactions have been preferred. This methodology has been largely described in the literature, however, when it comes to Knoevenagel-Doebner condensation involving phenolic aldehydes and malonic acid, the described processes use either domestic microwave oven (Sampath Kumar et al, 1998 , 2000 ; Mitra et al, 1999 ; Karchgaudhuri et al, 2002 ; Perez et al, 2003 ; Mogilaiah and Randheer Reddy, 2004 ; Gupta and Wakhloo, 2007 ; Rodrigues-Santos and Echevarria, 2007 ; Mobinikhaledi et al, 2008 ; Dhruva Kumar and Sandhu, 2010 ; Goel, 2012 ) or combined apparatus for ultrasound-microwave reactions (Peng and Song, 2003 ). Although this literature reports good conversions/yields, these procedures are hardly reproducible because of the use of relatively complicated and not readily accessible instrument, or of non-scientific ovens (i.e., household microwave oven) that are difficult to rely on.…”