Kinetics and Mechanism of the Br2-HCN Reaction

Article abstract of DOI:10.1021/j100132a023

The reaction between bromine and cyanide in aqueous acid solution (HClO4) has been studied at 25 deg C using a conventional spectrophotometric method.Under conditions of an excess of CN(1-), H(1+), and Br(1-) ions the experimental kinetic law has the form -d/dt = (a + b + c)/(1 + d, where a = 7.5 +/- 1 s^-1, b = 45 +/- 10 M^-1 s^-1, c = 48 +/- 4 M^-1 s^-1, and d = 12 +/- 4 M^-1.The results are consistent with a mechanism involving steps Br2 + CN(1-) -> BrCN + Br(1-) with rate constant k1 = (6.7 +/- 0.9) x 10⁹ M^-1 s^-1, Br3(1-) + CN(1-) -> BrCN + 2Br(1-) with k2 = (2.4 +/- 0.6) x 10⁹ M^-1 s^-1, and Br2 + HCN -> BrCN + Br(1-) + H(1+) with k3 = 48 +/- 4 M^-1 s^-1.A nonlinear regression method was successfully used in analysis of the experimental data.