Kinetics of the Highly Selective Liquid-Phase Oxidation of Side Chain Alkyl Groups in 2-Methylpyrazine and Picolines by Selenium Dioxide

Kinetics of the liquid-phase oxidation of alkyl groups in 2-methylpyrazine and picolines with selenium dioxide at moderate conditions were studied. Thus, 2-methylpyrazine was oxidized to pyrazinoic acid with selenium dioxide in pyridine at 115 °C with 99% selectivity at a 2-methylpyrazine conversion of 100% in 8 h. It was deduced that the reaction follows second-order kinetics and the activation energy was found to be 35 kcal/mol. The same reaction-scheme was found to hold for picolines oxidation to obtain picolinic acids. The byproduct selenium, formed in the reaction, was converted back to selenium dioxide by nitric acid oxidation with 100% selectivity.