Topochemical effect in thermalE–Zisomerization of azodioxides in solid state

Abstract

The thermally inducedE–Zisomerization of the benzeneazodioxide derivatives is studied in the solid polycrystalline state. The reactions are studied from the kinetic and mechanistic aspects. In contrast to the solution, where isomerizations of azodioxides occur through the formation of corresponding nitroso monomers, the topochemical effect in solid state lead to the mechanism that includes formation of the “torsional” transition state, as it is the case in other known cis–trans isomerizations. It is proposed that both the reactions in solid state, the nitroso monomer–dimer equilibrium, and isomerization about the azodioxide NN bond tentatively involve similar transition states. Copyright © 2015 John Wiley & Sons, Ltd.