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

Abstract

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 ? 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 (?S) and enthalpy (?H) changes of the pyrolysis are discussed.