Astatination homogeneous

Nucleophilic astatination of halobenzenes CgHjX (X = Cl, Br, I) in homogeneous mixtures with -C4H9NH2, (C2H5)2NH, and (C2Hj>3N at 210° C has led to the formation of astatobenzene with radiochemical yields of 75-90% 143, 144). A two-step process has been postulated [Eqs. (10) and (11)], with the latter reaction [Eq. (11)] as the ratedetermining step ... 

Astatination of aromatic compounds has been achieved in homogeneous solutions or in heterogeneous systems by melting the reacting components. In that latter case, catalysts may be applied that promote the exchange reaction. 

TABLE 2. Activation energy for homogeneous halogen exchange by astatine in halobenzenes. Reproduced with permission from Reference 24... 

TABLE 3. Yields and reaction times for homogeneous halogen exchange by astatine from halobenzenes (t = 200 °C)25... 

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