Thermal Stability and Decomposition Products of Hexabromocyclododecane

Abstract

The thermal stability and decomposition products of hexabromocyclododecane (HBCD), a widely used aliphatic brominated flame retardant, were investigated. HBCD thermal degradation was carried out in nitrogen and in air at moderate heating rates (10 °C/min) using thermogravimetric analyzers and a laboratory-scale fixed-bed reactor. The identification of decomposition products was based mainly on FTIR and gas-chromatographic/mass-spectrometric techniques. Quantitative data on hydrogen bromide formation and on the bromine distribution among the different product fractions were obtained. For the experimental conditions used in this study, about 75 wt % of the bromine is released as HBr, and 25 wt % is involved in the formation of high-molecular-weight bromo-organic compounds. The main pathways of HBCD thermal degradation were assessed, and a global mechanism for HBCD decomposition was proposed.

Levels, isomer profiles and chiral signatures of particle-bound hexabromocyclododecanes in ambient air around Shanghai, China

“…This indicates that stereoselective processes or isomer inter-conversion must occur at some point (Heeb et al, 2008b). As thermally labile compounds, HBCDs are subject to thermal rearrangement at temperatures above 160 C, resulting in the conversion of g-to a-HBCD, and thermal decomposition at temperatures above 240 C (Barontini et al, 2001). Inter-conversion was also proposed occurring at increased temperatures during the production or processing of HBCDcontaining materials (e.g., extruded polystyrene) (Heeb et al, 2008b;Köppen et al, 2008), which resulted in deviations from the relative abundance of HBCD diastereomers observed in the technical mixtures (e.g.…”

Simultaneous determination of hexabromocyclododecanes and tris (2,3-dibromopropyl) isocyanurate using LC–APCI-MS/MS

“…There are large differences in regards to the bioaccumulation potential among the individual diastereoisomers [2,10]. Previous studies found that ␥-HBCD can be transformed to ␣-HBCD at temperatures above 160 • C [11], and thus HBCD diastereoisomers cannot be separated by GC-MS and only total HBCD concentrations can be obtained by this method [12]. Liquid chromatography-mass spectrometry (LC/MS) and tandem mass spectrometry (LC/MS/MS) are found to easily separate HBCD diastereoisomers using reversed-phase columns [13][14][15][16][17].…”

Chemical Composition of Nanoparticles Released from Thermal Cutting of Polystyrene Foams and the Associated Isomerization of Hexabromocyclododecane (HBCD) Diastereomers

“…2(b)). Once the XPS board was heat-cut by a hot wire, HBCD diastereomers changed a little to 78%, 13%, and 9% for α-, β-, and γ-HBCD, respectively, which is close to thermal equilibrium (Peled et al, 1995;Barontini et al, 2001). Overall, compared to EPS, thermal cutting of XPS did not cause significant HBCD diastereoisomer conversion.…”