Thermal Characterization and Heat Capacities of Seven Polyphenols

Area of Science:

• Analytical Chemistry
• Materials Science
• Physical Chemistry

Background:

• Polyphenolic compounds are vital in pharmaceuticals, cosmetics, and food industries.
• Accurate physicochemical characterization of polyphenols is essential for their applications.

Purpose of the Study:

• To investigate the thermal behavior of seven key polyphenols.
• To determine melting temperatures, enthalpies of fusion, decomposition temperatures, and heat capacities.
• To compare experimental data with existing literature and evaluate predictive methods.

Main Methods:

• Differential Scanning Calorimetry (DSC) for thermal transitions and heat capacity.
• Thermogravimetric Analysis (TGA) for decomposition temperatures.
• Group contribution method (Marrero and Gani) for property estimation.

Main Results:

• All seven polyphenols (trans-resveratrol, trans-polydatin, kaempferol, quercetin, myricetin, hesperidin, (-)-epicatechin) were thermally stable until melting, followed by rapid decomposition.
• Myricetin exhibited polymorphic behavior with two phase transitions before melting.
• Heat capacities showed minimal temperature dependence within the 283.15 K to 363.15 K range.
• The Marrero and Gani group contribution method accurately predicted melting temperatures.

Conclusions:

• Experimental thermal data were obtained for seven important polyphenols.
• The study confirms the thermal stability profile and highlights the unique polymorphic behavior of myricetin.
• Validated predictive methods can reliably estimate thermal properties, aiding in the characterization of polyphenols.