Stereochemistry of LinB-catalyzed biotransformation of δ-HBCD to 1R,2R,5S,6R,9R,10S-pentabromocyclododecanol.

The haloalkane dehalogenase LinB from Sphingobium indicum B90A converts β-hexachlorocyclohexane (β-HCH), the most persistent HCH stereoisomer, to mono- and dihydroxylated metabolites. Recently, we reported that LinB also transforms α-, β- and γ-hexabromocyclododecanes (HBCDs), which are structurally related to HCHs. Here, we show that LinB catalyzes the hydroxylation of δ-HBCD to two pentabromocyclododecanols (PBCDOHs) and two tetrabromocyclododecadiols (TBCDDOHs).

Crystal structure of δ-isobutoxypentabromo-cyclododecanes, kinetics and selectivity of their isomerization during thermal treatment of flame-proofed polystyrenes.

Hexabromocyclododecanes (HBCDs) are persistent organic pollutants now ubiquitous in the environment. Technical HBCD mixtures and with it flame-proofed polystyrenes (FP-PS) also contain isobutoxypentabromocyclododecanes (iBPBCDs) as minor constituents, which are possibly released together with HBCDs. So far, eight diastereomeric pairs of enantiomers named as α-, β-, γ-, δ-, ϵ-, ξ-, η-, and θ-iBPBCDs with proportions of 10%, 5%, 2%, 21%, 11%, 11%, 12% and 28% were found in technical HBCD.

Thermally-induced transformation of hexabromocyclo dodecanes and isobutoxypenta bromocyclododecanes in flame-proofed polystyrene materials.

Polystyrenes (PS) are produced in quantities exceeding 10 Mt y(-1). They are used for insulation and packaging materials, often in flame-proofed forms with hexabromocyclododecanes (HBCDs) added as flame retardants. Polystyrenes are also constituents of plastic debris found in the aquatic environment.

Isobutoxypentabromocyclododecanes (iBPBCDs): a new class of polybrominated compounds.

Isobutoxypentabromocyclododecanes (iBPBCDs) represent a new class of polybrominated compounds found in several flame-proofed polystyrene materials and in a technical mixture of hexabromocyclododecanes (HBCDs). Of the 64 stereoisomers possible, we now have analytical evidence for 16 different stereoisomers. By reversed- and chiral-phase liquid chromatography we distinguished 8 diastereomeric pairs of enantiomers, named alpha-, beta-, gamma-, delta-, epsilon-, xi-, eta-, and theta-iBPBCDs in accordance with their chromatographic retention on a C(18)-RP-column.