| Abstract: | The H/D exchange reaction and the rotational dynamics of heavy water (D2O) are studied at 50 degrees C in the ionic liquid, 1-butyl-3-methylimidazolium chloride (bmim]Cl]), in the D2O] range of 3-55 M. The initial H/D exchange rates are observed as 1.0 x 10(-7), 4.5 x 10(-6), 1.0 x 10(-5), 4.1 x 10(-5), 1.1 x 10(-4), and 3.7 x 10(-4) s(-1), respectively, at D2O] of 2.8, 7.1, 8.1, 11, 15, and 25 M. The rate is very slow and less than 10(-5) s(-1) at D2O] below approximately 7 M. It steeply increases to the order of 10(-4)s(-1) for 7 M < D2O] < 10 M, and linearly increases with D2O] in the more water-rich region. The intercept of the linear region at D2O] = approximately 9 M is interpreted by considering that each chloride anion deactivates 1.6 equiv water molecules due to the strong solvation. Correspondingly, the rotational correlation time of D2O at D2O] < 7 M is 1 order of magnitude larger than that in water-rich conditions. |
