Green, solventless debromination of C₇₀Br₁₀ to C₇₀ with CsI

A smooth, solventless and solid state debromination of C70Br10 can be achieved in a CsI matrix with the restoration of the pristine C70 in quantitative yields. Such debromination reaction was studied with FT-IR spectroscopy and its kinetics was fitted by a pseudofirst order law, with a rate constant in the range of 3.6-5.2 x 10(-5) s(-1). The thermal properties of the compound C(70)Br(10 )were studied with TGA and DSC analysis focusing on the thermal decomposition processes. From the DSC data both the activation energy for the thermal decomposition of C(70)Br(10 )as well as its enthalpy of formation were determined. Some considerations on the relative weakness of C-Br bonds in brominated fullerenes compounds were made. Accordingly, the debromination mechanism is discussed in terms of unimolecular elimination reaction (E1) in a concerted mechanism which leads to the restoration of the pristine C-70 fullerene.