title: Debromination of hexabromobenzene by its co-grinding with CaO.
abstract: A hexabromobenzene (HBB, C6Br6) 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 CaBr2, C and CaCO3 besides excess CaO in the product. CaBr2 in the product tends to absorb moisture from the atmosphere to form CaBr2 x nH2O. 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.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan. zhangqw@tagen.tohoku.ac.jp
authors.forename: Qiwu
authors.initials: Q
authors.lastname: Zhang
authors.forename: Hiroki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Fumio
authors.initials: F
authors.lastname: Saito
authors.forename: Michel
authors.initials: M
authors.lastname: Baron
mesh_terms: D001966:Bromine / Q000737:chemistry*; D001969:Bromobenzenes / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry; D004785:Environmental Pollutants; D005411:Flame Retardants; D010087:Oxides / Q000737:chemistry; D014050:Toluene / Q000737:chemistry
chemical_list: D001969:Bromobenzenes; D017610:Calcium Compounds; D004785:Environmental Pollutants; D005411:Flame Retardants; D010087:Oxides; D014050:Toluene; C016538:lime; D001966:Bromine; C017363:hexabromobenzene