Synthesis and characterization of 32 polybrominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs) are widely used as additive flame re tardants in, for example, textiles, computers, television sets, and other e lectrical appliances. PBDEs are ubiquitous environmental contaminants, pres ent also in humans. The environmental levels of the PBDEs are, however, sti ll in general lower than those of polychlorinated biphenyls (PCBs). However , while the levels of PCBs generally are decreasing, those of the PBDEs are increasing in, for example, human milk. In the present study 32 individual PBDE congeners were synthesized and characterized. Physicochemical paramet ers including melting points and UV, H-1 NMR, and mess spectra are reported . Twenty-nine monobrominated to heptabrominated diphenyl ethers were synthe sized by the coupling between four diphenyliodonium salts and nine phenolat es. One tetrabromodiphenyl ether and two hexabromodiphenyl ethers were synt hesized by bromination of two different PBDEs. Twenty-one of the PBDEs and two of the iodonium salts, 2,2',4,4'-tetrabramodiphenyliodonium chloride an d 3,3',4,4'-tetrabromodiphenyliodonium chloride, are to the authors' knowle dge described for the first time. These synthesized reference compounds wil l aid in the identification and quantification of PBDEs present in environm ental samples and will allow further assessment of PBDE toxicity.