Reactions of trifluoromethyl radicals with bromine, chlorine and hydrogen chloride

Abstract

Hexafluoroacetone has been photolyzed with HCl and with mixtures of HCl+Cl₂, HCl+Br₂, Br₂+Cl₂, and Cl₂+HBr. Absolute Arrhenius parameters have been obtained for the reaction, CF₃+HCl→CF₃H+Cl (4) using the combination of CF₃ radicals as a reference reaction. The values of A₄ and E₄ have been combined with the results obtained from competitive experiments on the above pairs of reactants and from previous work to give other Arrhenius parameters as follows: CF₃+HCl→CF₃H+Cl k= 1.7 × 10¹¹ exp (–5100/RT) CF₃+HBr→CF₃H+Br k= 6.0 × 10¹¹ exp (–2900/RT) CF₃+Cl₂→CF₃Cl+Cl k= 7.7 × 10¹² exp (–3600/RT) CF₃+Br₂→CF₃Br+Br k= 2.3 × 10¹² exp (–700/RT) CF₃+I₂→CF₃I+I k= 2.6 × 10¹² exp (0/RT) units; cm³mole^–1sec^–1