2- and 3-furancarboxylic acids: a comparative study using calorimetry, IR spectroscopy and X-ray crystallography

A thermophysical study by DSC for the 2- and 3-isomers of furancarboxylic acid, in the temperature intervals between T=268 K and their respective melting temperatures has been carried out, and an enhancement in the heat capacity curve of the 3-isomer was observed. The IR spectroscopy did not show significant changes either in the frequency band or in the relative band intensity in the temperature range where the small heat absorption occurs. The X-ray analysis reveals that the main differences in their supramolecular structure consist of the assembly of the carboxylic dimers into sheets.