Effects of pressure on organic reactions III : the base-catalyzed reduction of diisobutylketone

Abstract

The rate of the base-catalyzed reduction of diisobutylketone to carbinol in n-butanol solution has been measured in the range 96～112℃ at pressures up to 1, 450 bar. The reaction is kinetically of second order in both ketone and base, and is accelerated by pressure. The energies of activation at 1 bar and 964 bar are 26.4 kcal/mole and 26.6 kcal/mole, respectively, and the volume of activation is about -13cm^3/mole at 99.00～100.27℃. These results show favorably that the slow step is a bimolecular reaction, probably the hydrogen abstraction, between two ketone-alkoxide adducts formed is rapidly established initial equilibrium. In addition, it may be deduced that the acceleration of the reaction under pressure arises predominantly from the enhanced addition of alkoxide anion to ketone.