C8K in benzene byproducts: KBr; under Ar suspn. of C8K in benzene soln. of cyclohexane was heated to reflux, MeBBBr2 was added dropwise in the course of 1 h with stirring; refluxing and stirring for 24 h, then stirring at room temp. for 2 more days; filtration, adding of EtLi in benzene to filtrate for removing of MeBBr2; filtration, evapn., sublimation of residue in vac.;