Thermal and oxidative disproportionation in amine degradation—O2 stoichiometry and mechanistic implications

Three modes of amine degradation have been previously identified—direct oxidation by metal ions, thermal disproportionation and autoxidation. Results are presented in which products of disproportionation reactions of quaternary compounds are compared to those seen in the thermal degradation of methyldiethanolamine, MDEA. This strongly suggests a role of a quaternary or a protonated amine intermediate in this reaction. Products of MDEA autoxidation at 140 °C also show characteristics of disproportionation reactions. Potential mechanisms are presented to account for the products seen.