The thermal stability of pseudocyclic and cyclic N-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ3-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. Peak decomposition temperatures (Tpeak) were observed within a wide range between 120 and 270 °C. Decomposition enthalpies (ΔHdec) varied from −29.81 to 141.13 kJ/mol. A direct comparison between pseudocyclic and cyclic NHIs revealed high Tpeak but also higher ΔHdec values for the latter ones. NHIs bearing N-heterocycles with a high N/C-ratio such as triazoles show among the lowest Tpeak and the highest ΔHdec 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.
本文研究了假环和环状N-杂环稳定的(羟基)芳基和二甲基(芳基)-λ3-碘烷(NHIs)的热稳定性,通过热重分析(TGA)和差示扫描量热法(DSC)进行了研究。峰值分解温度(Tpeak)在120℃至270℃之间。分解焓(ΔHdec)变化从-29.81至141.13 kJ/mol。假环和环状NHIs之间的直接比较显示出后者有更高的Tpeak和更高的ΔHdec值。具有高N/C比率的N-杂环的NHIs,如三唑衍生物,显示出最低的Tpeak和最高的ΔHdec值。本文还将NHIs与已知的(伪)环状苯碘氧烷进行了比较,并进一步将它们的热稳定性与模型氧化反应的反应性相关联。