Retro-[3 2]-cycloaddition reactions in the decomposition of five-membered nitrogen-containing heterocycles

Abstract

(Chemical Equation Presented) Nitrogen-containing heterocycles form the basis for a new generation of high-energy density materials, and they serve as model compounds for nitrogen-containing fuels, such as coal and biomass, and they form the backbone of ionic liquids. A novel retro-[3 + 2]-cycloaddition to a three-membered diene and a two-membered dienophile, analogous to a retro-Diels-Alder reaction, may constitute an important initial reaction step in the thermal decomposition of these heterocyclic compounds. We investigate the kinetics and thermodynamics of these reactions for the heterocycles pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, 1,2,5-triazole, 1,3,4,-triazole, 1..