Thermal stability of N -heterocycle-stabilized iodanes – a systematic investigation

The thermal stability of pseudocyclic and cyclic N -heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ 3 -iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. Peak decomposition temperatures ( T peak ) were observed within a wide range between 120 and 270 °C. Decomposition enthalpies (Δ H dec ) varied from −29.81 to 141.13 kJ/mol. A direct comparison between pseudocyclic and cyclic NHIs revealed high T peak but also higher Δ H dec values for the latter ones. NHIs bearing N -heterocycles with a high N/C-ratio such as triazoles show among the lowest T peak and the highest Δ H dec values. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation.