The Thermal Gas-phase Decomposition of Methyl Iodide

The thermal gas-phase decomposition of methyl iodide diluted in Ar has been studied behind shock waves over the temperature range between 1050 and 1500 K and the total density range of 3.5×10−6–3.9×10−5 mol cm−3. The decomposition was monitored by means of the UV absorption of CH3I at 259 or 275 nm. The initiation reaction was found to be the C–I bond fission, and the process proceeded in the low-pressure region under the present experimental conditions. The low-pressure limit rate constant was obtained as: k_2nd=10^15.40±0.26exp{-(42.56±1.50 kcal mol^-1)/RT}cm^3 mol^-1s^-1. Applying the RRKM strong collision theory, the collision efficiency factor was estimated to be 0.018 at 1300 K.