Debromination of hexabromobenzene by its co-grinding with CaO

• Published in: Chemosphere (Oxford) 2002-09, Vol.48 (8), p.787-793
• Main Authors: Zhang, Qiwu, Matsumoto, Hiroki, Saito, Fumio, Baron, Michel
• Format: Article
• Language: English
• Subjects: Applied sciences; Bromide; Bromine - chemistry; Bromobenzenes - chemistry; Calcium Compounds - chemistry; Chemical and Process Engineering; Chemical engineering; Chemical Sciences; Engineering Sciences; Environmental Pollutants; Exact sciences and technology; Fire retardant; Flame Retardants; HBB; Mechanochemistry; Medicinal Chemistry; or physical chemistry; Organic chemistry; Other wastes and particular components of wastes; Oxides - chemistry; Pollution; Radical; Theoretical and; Toluene - chemistry; Wastes
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(02)00138-8

A hexabromobenzene (HBB, C 6Br 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· nH 2O. 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.