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Aqueous bromine atoms were produced by laser flash photolysis of 1,2-dibromoethane at 248 nm in solutions containing bromide ions. Forward and reverse rate constants of the title reaction were determined as functions of temperature. An analysis of potential sources of systematic errors shows that the measured forward and reverse rate constants have relative uncertainties (±σk/k) of ~10 and ~25%, respectively, over the temperature range from 10.5 to 50 °C. The Arrhenius parameters are (kf ± 10%) = 5.1 × 10¹² exp (−1812/T) M^-1 s^-1 and (kr ± 25%) = 2.5 × 10¹⁰exp (−4068/T) s^-1. The equilibrium constant is found from the ratio of kf/kr:  (Keq ± 30%) = 2.0 × 10² exp (2256/T) M^-1 or (3.9 ± 1.2) × 10⁵ M^-1 at 298 K. The reaction entropy and enthalpy are ΔSR° = 44 ± 6 J mol^-1 K^-1 and ΔHR° = −19 ± 2 kJ mol^-1, respectively. The corresponding reaction reduction potential is ΔE° = 0.33 ± 0.01 V, in very good agreement with that calculated from half-cell potentials. In addition, preliminary rate constants for Br2^-• + Br2^-• → Br3^- + Br^- and the hydrogen abstraction reaction (Br^• + BrCH2CH2Br → ^•CBrH−CH2−Br + H⁺ + Br^-) are reported.

We report a family with Machado-Joseph disease (MJD) that was previously diagnosed with dentatorubral-pallidoluysian atrophy (DRPLA), on the basis of the neuropathologic findings. Because the clinical and pathologic reevaluation strongly suggested a diagnosis of MJD, we conducted a genetic study in the family. Two patients, aged 38 and 40, revealed CAG repeat lengths of the MJD1 gene of 80, 28 and 75, 14, confirming a final diagnosis of MJD.