Steric and Electronic Effects on Thermal Stability of Nitrile N-Oxide: a Case Study of Naphthalen-2-ol Derived Substrates

This paper describes the syntheses of four types of nitrile N-oxides (NOs) and studies on the thermal isomerization of NOs to isocyanates (Isocs). It is found that a bulky electronwithdrawing substituent at the ortho position of NO tends to suppress the thermal degradation of NO. The reaction rates for the thermal reactions appear to be dependent on the initial concentration. The reaction orders are analyzed in order to understand the reaction mechanism for the isomerization. It is indicated that the isomerization of NO could proceed via a reversible formation of polymeric intermediate.