Mechanism of thermal decomposition of tetrabromobisphenol a (TBBA)

This study presents a detailed investigation into the gas-phase thermal decomposition of tetrabromobisphenol A (TBBA), that is, the most widely used brominated flame retardant (BFR). Elimination of one of the methyl groups characterizes the sole dominant channel in the self-decomposition of the TBBA molecule at all temperatures. A high-pressure rate constant for this reaction is fitted to k(T) = 2.09 × 10¹⁰T^1.93 exp( -37000/T) s^-1. The high A factor and low activation energy for this reaction arise from the formation of a delocalized radical upon the loss of a methyl group. We calculate rate constants for the bimolecular reactions of TBBA with H, Br, and CH₃ radicals. Kinetic and mechanistic data provided herein should be instrumental to gain further understanding of the fate of TBBA during thermal degradation of materials laden with this BFR.