Decabromobiphenyl

First, thermal behaviour of decabromobiphenyl ether 1 will be described. The thermal reactivity of this compound depends on the applied conditions the pure compound reacts completely different in comparison to its reaction in polymeric matrices. Thermolysis of the pure compound gives a good yield (60 %) of hexabromobenzene. The main products obtained by incineration in th DIN oven at three temperatures for pure 1 and of 1 within a polypropylene matrix are shown in Table 1. 

Table 1. Main Products obtained by Incineration of Decabromobiphenyl ether 1 at three Different Temperatures Yields are in Percent by Weight (ref. 12)...

For the thermochemistry of pure decabromobiphenyl ether, the following mechanistic scheme has been suggested (Scheme 2) (ref. 11). 

Scheme 2. Proposed Mechanism for Thermolysis of Pure Decabromobiphenyl Ether (1)...

Thermochemistry in the polymeric matrix follows a different pattern. Decabromobiphenyl ether 1 does cyclize according to the following reaction yielding brominated dibenzofurans (PBDF). The optimal yield for PBDF depends on the applied burning temperature (refs. 14,15) this itself depends on the kind of polymeric matrix, which is shown below for incineration at the DIN-oven (Fig. 5). 

Fig. 5. Yields of Brominated Dibenzofurans from Decabromobiphenyl Ether as Dependent on Temperature and Amount of Sb203 (Synergist) in the Polymeric Matrix (Polybutylene-terephtalate).

Fig. 7. Influence of Various Metal Species on PBDD/F Concentrations during Incineration of Decabromobiphenyl ether in Polybutyleneterephtalate at 500°C (BIS-Furnace).

The difference in reactivity is not as much as is generally observed in nucleophilic aromatic substitution in solution by an addition-elimination mechanism (ref. 25). Substituents with electron withdrawing capabilities enhance the rate of the reaction therefore decabromobiphenyl ether reacts nearly 2 times faster than 1,2,3,4-tetrabromodibenzodioxin. 

Similarly, toluene suspensions of the polystyrene housing of TV sets were examined by means of TPPy-FTMS (300-1200 K) [224], Diphenylether (DPE) was evidenced by peaks at m/z 141, 142 and 170 and decabromobiphenyl (DBBP) by m/z 943 and 864. Decabromodiphenyl ether (DBDPE) was recognised by thermal degradation products around m/z 800... 

Common Name Decabromobiphenyl Synonym PBB-209 Chemical Name ... 

Decaborane(14), 4 185-186, 189 physical properties of, 4 184t Decabromobiphenyl, physical properties of, 4 355t... 

Ambient air sampling on plant property of industrial bromine extraction and bromo-organics synthesis facilities revealed the presence of tetrabromobisphenol A (N.D. —28 ng/m ), decabromobiphenyl ether (N.D. —72 ng/m3), tris(2,3-dibromopro-pyljphosphate (N.D. —60 ng/m3) and l,2-bis(tribromophenoxy)ethane (N.D. —183 ng/m3). 

Hexabromobiphenyl is the most abundant congener in the mixtures (53.9-68.0%), followed by 7.0-27.3% of 2.2. 3.4.4. 5.5 -hcptabromobiphcn l. Commercial octabromobiphenyl mixtures contained a large proportion (47.4-60.0%) of nonabromobiphenyl congeners, whereas commercial decabromobiphenyls contain predominately (96.8%) decabromobiphenyl congener. 

Limited data are available on health effects of commercial decabromobiphenyl and octabromobiphenyl mixtures, although the hexabromobiphenyl mixtures FireMaster BP-6 and FireMaster FF-1 have been extensively tested. Most of the information on human health effects of PBBs comes from studies of Michigan residents who accidentally ingested milk, meat, and eggs that came from farms that used animal feed contaminated with FireMaster FF-1. In 1973, livestock on certain farms in Michigan were exposed to... 

Other effects of oral PBB exposure include decreased thyroid function, body weight loss, and liver cancer. Adverse hepatic as well as dermal and ocular effects have been observed in a limited number of dermal studies in animals. No significant adverse effects were observed in animal inhalation studies of PBBs, but only two studies have been conducted (one with octabromobiphenyl and one w ith decabromobiphenyl). 

Unspecified signs of ocular irritation were observed in rats intermittently exposed to a high (5,000 mg/m ) dust concentration of decabromobiphenyl mixture for 4 weeks, but severity was not reported, and recovery was not assessed. Octabromobiphenyl and decabromobiphenyl mixtures caused mild eye irritation in rabbits when applied as a dry solid. Histopathological changes have not been observed in the eyes of rats or mice exposed orally to FireMaster FF-1 or FireMaster BP-6 in studies of acute, intermediate, or chronic duration. Xerophthalmia (extreme dryness of the conjunctiva) was reported in rats fed FireMaster BP-6 in an intermediate-duration study. Based on effects in animals, direct exposure to PBBs is likely to be irritating to human eyes. 

No deaths occurred in groups of five male and five female rats that were exposed to a decabromobiphenyl dust mixture at concentrations ranging from 5 to 5,000 mg/m concurrently with starch dust (6 mg/m ) for 6 hours/day, 5 days/week for 4 weeks (Millischer et al. 1980). Information on lethality of inhaled hexabromobiphenyl PBB mixtures was not located. 

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