The role of water and acid catalysis in the reaction of acetone with hydrogen peroxide: A DFT study

Abstract

The proposed first step in the synthesis of peroxide explosives such as triacetone triperoxide (TATP) is investigated computationally at the M06-2X/6-311+G(2d,p) level in SMD water. The reaction between acetone and hydrogen peroxide is thought to produce 2-hydroperoxy-2-isopropanol (HPP) as the first intermediate. The conformers of HPP are optimized and described structurally and thermodynamically. A nucleophilic mechanism for the formation of HPP, with and without a strong Bronsted acid catalyst, is considered. The thermodynamic properties associated with each step of the mechanism, and for the overall reaction, are determined; overall, ΔG* = +6.3 kJ/mol. Without an acid catalyst, the transition state free energy ranges from 167 kJ/mol without any assisting water molecules, to 84 kJ/mol with the assistance of catalytic water. With an acid catalyst, the free energy reaction barrier drops to 22 kJ/mol. This pathway consists of a network of three water molecules facilitating proton transfer from H2O2 to acetone.