Synthesis and properties of 5-phenoxyfurancarboxylic acids

Abstract

Furancarboxylic acids were prepared by oxidation with Ag2O of the corresponding 5-(X-phenoxy)-2-furaldehydes (X = 4-OCH3, 4-SCH3, 3-NHCOCH3, 4-Cl, 4-Br, 4-COOC2H5, 3-NO2, and 4-NO2. The appearing pKa values of the synthesized acids were determined by potentiometric titration. The transfer effect of the substituents through the oxygen bridge is discussed and the transfer coefficient is compared with π' values of other linking groups in the furan series.