THERMAL-DECOMPOSITION OF ALPHA-TETRALYL HYDROPEROXIDE IN THE PRESENCEOF THE PHENYLPROPIONIC ACIDS

The thermal decomposition of cinnamic, p-coumaric, ferulic and sinapic acids has been investigated by employing TG/DTG/DTA methods in the te mperature range at ambient to 500 degrees C in a self-generated atmosp here, It established high thermal stability of the investigated acids. The presence of two methoxy groups in the structure increases the the rmal stability of sinapic acid. The thermal decomposition of alpha-tet ralyl hydroperoxide (THPO) in the presence of phenylpropionic acids ha s been investigated under nonisothermal conditions. p-Coumaric acid in hibited THPO thermal decomposition in the system containing 0.006, 0.0 18 mM acid and 0.427 mM THPO. The increased content of p-coumaric acid (0.049 and 0.06 mM) in the reaction system leads to rapid reaction wi th tetralylperoxy radicals and the formation of THPO. Cinnamic acid in teracts with THPO radicals and suppresses hydroperoxide free-radical-i nduced decomposition. Participation of cinnamic acid is not registered in the chain-transfer reaction leading to THPO formation (investigate d systems -0.427 mM THPO and 0.006-0.06 mM cinnamic acid), Ferulic aci d inhibits THPO thermal decomposition in all the mol proportions studi ed (THPO: ferulic acid 1, 0.012 to 0.180). Ferulic acid is regenerated as a result of the interaction between ferulic radicals and THPO. Low concentrations of sinapic acid inhibit THPO decomposition. (C) 1998 E lsevier Science B.V.