Thermo-oxidative degradation of styryl derivatives of pyridine-N-oxides

Kinetic parameters of thermo-oxidative degradation of various derivatives of pyridine-N-oxide have been calculated. Thermo-oxidative degradation is a multi-stage process. 4-Substituted pyridine-N-oxides are more thermally stable than the 2-substituted isomers. Stability of 4-substituted pyridine-N-oxides towards thermo-oxidation is enhanced in the presence of electron-donating ability of the substituent. In the case of 4-styrylpyridine-N-oxide, the rate-limiting stage of thermo-oxidation is a chemical reaction; for other studied compounds, the limiting stage is free nucleation and further nuclei growth.