The thermal decomposition of trifluoromethyl iodide

Abstract

The pyrolysis of trifluoromethyl lodide has been investigated under two entirely different sets of conditions (i) in a low pressure flow system (ii) in sealed tubes at higher pressure in the flow system, nickel and pyrox reaction vessels were used. The nickel vessel was used when no material was added to react with OF5 radicals which it was feared would attack pyrex glass. During the course of the Investigations, it was deoided to add toluene, hydrogen iodine as additional reagents. The conditions in the flow system were varied within the following Limits:- Temperature 698°K to 797°K Contact Time. 526 to 2.52 secs. CF3I Pressure 0.016 mms to 0.58 mms. Toluene Pressure 0 to 3.76 mms. Hydrogen Iodide Pressure 0 to 4.08 mms. N2 carrier gas Pressure 1.50 to 14.5 mms. A carrier gas Pressure 1.59 to 12.4 mms. C6H5OF5 Pressure 0 to 2.65 mms. Pressure of added iodine (as atoms) 0 to. 0176 mms. Surface to Volume Retio 1.95 to 6.15 cms⁻¹ only pyrex reaction vessels were used in the sealed tube reactions. OF5 I was never heated alone but always in the presence of HI. In these reactions, conditions were varied within the Limits:- Temperature 440°K to 522°K Reaction Time 10,800 secs. To 259,200 secs. CF5I Pressure 4.0 mms to 57 mms. Hydrogen Iodide Pressure 5.7 mms to 565 mms. Pressure of added iodine (as molecules) 0 to 5.0 mms. An attempt was made to find the stoichiometry of the reaction under all conditions. In order to do this, titration, Low temperature distillation, U.V. and I.R. absorption spectrophotometry and mass spectrometry were used. A reaction scheme has been proposed which agrees with the major experimental findings.