Kinetics of thermal bromination of trifluoroacetaldehyde and the bond dissociation energy D(CF3CO—H)

Abstract

The kinetics of the thermal bromination of CF₃CHO vapour were studied in the range 198–303°C. Between 240–303°C, the observed rate law is compatible with a chain reaction involving M + Br₂⇌M + 2Br Br + CF₃CHO → HBr + CF₃CO (7) plus other reactions. We obtain log k₇(cm³ mol^–1 s^–1)=(2.80±0.52)× 10¹² exp –(27,600±800 J)/RT from which is derived the bond dissociation energy D(CF₃CO—H)= 381±8 kJ mol^–1 at 298 K. The reactivities of CF₃CHO and CH₃CHO towards free radicals are discussed.