Debromination of hexabromobenzene by its co-grinding with CaO

Abstract : A hexabromobenzene (HBB, C 6 Br 6) powder was subjected to co-grinding with excess CaO powder in air using a planetary ball mill to investigate mechanochemical debromination of the HBB sample. The reaction proceeds smoothly with an increase in both grinding time and molar ratio of CaO addition. The co-grinding enables us to debrominate HBB, forming CaBr 2 , C and CaCO 3 besides excess CaO in the product. CaBr 2 in the product tends to absorb moisture from the atmosphere to form CaBr 2 Á nH 2 O. The reaction yield is quantitatively evaluated by measuring the amount of water-soluble bromide through water washing and the amount of unreacted HBB through toluene washing. It is found that almost 100% of debromination is achieved by 6 h grinding with the molar ratio kept constant at 2:1. Radicals are detected in the ground products, possibly due to rupture in the covalent bonds of C–C and C–Br in HBB.
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Qiwu Zhang, Hiroki Matsumoto, Fumio Saito, Michel Baron. Debromination of hexabromobenzene by its co-grinding with CaO. Chemosphere, Elsevier, 2002, 48 (8), pp.787 - 793. ⟨10.1016/S0045-6535(02)00138-8⟩. ⟨hal-01788901⟩

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