Thermochemistry of pyrolyzed rutin and its esters prepared from facile biocatalytic route

Pyrolysis of quercetin-3-O-rutinoside or rutin and its esters were investigated. Purified ester samples were prepared from lipase-catalyzed esterification of the parent flavonoid, i.e., rutin using acyl donors with different carbon chain length. X-ray diffraction revealed the presence of crystalline peaks in the rutin esters. The degradation activation energies (Ea) as a function of conversion degree alpha were determined using Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods, with corroborative results. Disparity in Ea implies distinct thermal degradation routes. For all studied compounds, degradation is a non-spontaneous process. The presence of acyl moieties and their corresponding carbon chain length in relation to thermodegradation profiles, Ea, entropy (Delta S) and enthalpy (Delta H) changes of the pyrolysis are discussed.