Thermal decomposition of tetraalkylammonium iodides

A number of tetramethylammonium (TMA) iodides, including mono-, tri-, and pentaiodide, were synthesized. Thermal decomposition of samples was investigated by simultaneous TG–DSC analysis accompanied by gaseous IR- and mass-spectrometry analyses. Two different reaction pathways have been observed for TMA pentaiodide at different heating rates. At low heating rates (1–5 K min^?1), a gradual mass loss takes place and a stability plateau due to monoiodide formation exists on TG curve. At high heating rates (10, 15 and 7 K min^?1 as the in-between stage), there are only two peaks on DTG curve (instead of three for lower heating rates) and no monoiodide formation is observed as the sample decomposes completely before 350 °C.