title: Crystal structure analysis of enantiomerically pure (+) and (-) beta-hexabromocyclododecanes.
abstract: The molecular structures of individual HBCD stereoisomers are not elucidated yet. Recently, we isolated 8 of the 16 possible stereoisomers from a technical HBCD mixture and tentatively assigned their relative configurations. Herein we report on the isolation of enantiomerically pure (+) and (-) beta-HBCDs, both obtained from preparative chiral-phase liquid chromatography, and we present their absolute configurations determined from X-ray diffraction analysis. The absolute configuration of (+) beta-HBCD was found to be (1S,2S,5S,6R,9S,10R), while the one of (-) beta-HBCD was assigned to (1R,2R,5R,6S,9R,10S). The given structural information allows, for the first time, the unambiguous identification of these two important HBCD stereoisomers, which are typically found in technical products at proportions of about 3-5% for each enantiomer.
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory of Solid State Chemistry and Catalysis, Uberlandstrasse 129, CH-8600 Dübendorf, Switzerland. norbert.heeb@empa.ch
authors.forename: Norbert V
authors.initials: NV
authors.lastname: Heeb
authors.forename: W Bernd
authors.initials: WB
authors.lastname: Schweizer
authors.forename: Peter
authors.initials: P
authors.lastname: Mattrel
authors.forename: Regula
authors.initials: R
authors.lastname: Haag
authors.forename: Martin
authors.initials: M
authors.lastname: Kohler
mesh_terms: D002853:Chromatography, Liquid; D018360:Crystallography, X-Ray / Q000379:methods; D006842:Hydrocarbons, Brominated / Q000737:chemistry* / Q000302:isolation & purification; D013058:Mass Spectrometry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D006842:Hydrocarbons, Brominated; C089796:hexabromocyclododecane