Kinetics of the reaction of aquomanganese(III) ions with isopropanol

Abstract

The kinetics and products of the reaction of manganic ions with isopropanol have been investigated in perchlorate media at an ionic strength of 4.0 with [HClO₄]= 0.5–3.7 M. One molecule of acetone is formed for every two magnanic ions which disappear. The reaction is first order in [Mn(III)], first order in [isopropanol], and insensitive to changes in acid concentration at [isopropanol]< 4 M and [Mn(III)] >2 × 10^–4M. This is discussed in terms of the hydrolysis of the manganic ion and the protonation of the isopropanol, and it is suggested that the rate-determining step is the reaction of the hexa-aquomanganic ion with unprotonated isopropanol. The energy of activation and temperature-independent factor are derived for this reaction. The isotope effect suggests that hydrogen atom abstraction occurs from the αC—H bond.