Pulse radiolysis study of the oxidation of the I~- ions with the radical anions Br_2~(·-) in an aqueous solution: formation and properties of the radical anion BrI~(·-)

摘要

The radiation chemical redox transformations in solutions of bromides in the presence of minor additives of iodides were studied by pulse radiolysis. The change in the concentrations of the Br- and I~- ions changes the ratio of the formed short-lived radical anions Br_2~(·-) , BrI~(·-), and I_2~(·-). The spectrum of the mixed radical anion BrI~(·-) contains a broad optical band at 370 nm with ε_(370) = 9650 L mol~(-1) cm~(-1). The reduction potential of the BrI~(·-)/Br~-, I~- pair is 1.25 V. The rate constants for the forward and backward reactions Br_2~(·-) + I~- <->BrI~(·-) + Br~- are k_f = 4.3· 10~9 and k_r= 1.0-10~5 L mol~(-1) s~(-1), respectively; for the reactions BrI~(·-)~ <-> Br~- + I~·, k_f= 5.7·10~8 s~(-1) and k_r = 1.0·10~(10) Lmol~(-1) s~(-1).