Investigation of thermal-induced decomposition of iodoform

Abstract

This paper presents the results obtained after the investigation of thermal-induced decomposition of tri-iodo-substituted methane (iodoform), under non-isothermal conditions in dynamic oxidative atmosphere (air flow). Iodoform was obtained in our laboratory through haloform reaction, namely the halogenation of dimethyl ketone in the presence of a base, and later purified according to literature. The kinetic study for the thermodegradation was carried out by processing the data by Friedman, Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose and modified nonparametric kinetic (NPK) methods. All the results obtained by the employment of isoconversional methods are in good agreement; the mean apparent activation energy was around 330 kJ mol−1, by all three methods. However, since variation larger than 10 % of E a versus α was noticed, the NPK method was employed, and the separation of physical versus chemical transformations of the sample was possible. NPK method suggested that the degradation of iodoform occur in two parallel processes, the main step being a chemical degradation (n = 1/3), while the parallel process is a physical–chemical one (n = 3/5; m = 1/3).