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Hexabromocyclododecane has 16 possible stereo-isomers. So far so good.
I found that:
134237-50-6 is the CAS of alpha-Hexabromocyclododecan
134237-51-7 is the CAS of beta-Hexabromocyclododecan
134237-52-8 is the CAS of gamma-Hexabromocyclododecan
3194-55-6 is the CAS of a mixture of different ...