Ultrasound-assisted Bromination. Part 2. Bromination of Fullerene Black: A Comparison with Carbon Black and Graphite

Fullerene black (FB) is the raw carbon soot produced during fullerene synthesis by arcing graphite electrodes under helium. When FB is extracted with toluene to remove C-60 and C-70 fullerenes (but not higher fullerenes), the extracted fullerene black (EFB) is produced. FB and EFB were brominated with liquid bromine and sonication in mild conditions. For comparison, graphite and N220 grade furnace carbon black were brominated in an ultrasonic field. The resulting brominated carbons were studied by thermogravimetric analysis, derivative thermogravimetry, differential thermal analysis and FT-IR spectroscopy. Under the conditions adopted, graphite was found completely unreactive with bromine while N220 carbon black yielded a brominated derivative with the composition C65Br. FB and EFB produced brominated derivatives with the composition C16Br. With the thermal analysis it was possible to distinguish between bromine adsorbed on fullerenic sites and bromine residual compound so that the brominated derivatives of FB and EFB can be described as [(C-16 (Br-0.7)(fullerenic)(Br-0.3)(residual)] and [C-16(Br-0.5)(fullerenic)(Br-0.5)(residual)], respectively. The incredible chemical adsorption power (chemisorption) of FB and EFB against N220 carbon black is disclosed.