Molecular Dynamics of Dimethyldioxirane C-H Oxidation

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Reaction Dynamics

Background:

• Dimethyldioxirane (DMDO) is a potent oxidizing agent.
• Understanding DMDO reaction mechanisms is crucial for synthetic chemistry.
• Hydrogen atom abstraction is a key step in DMDO reactions.

Purpose of the Study:

• To investigate the reaction pathways of DMDO with isobutane using molecular dynamics.
• To elucidate the role of solvent effects on DMDO reaction outcomes.
• To characterize the transition states and intermediate species involved.

Main Methods:

• Performing molecular dynamics simulations.
• Utilizing an implicit acetone solvent model (SMD).
• Analyzing reaction trajectories to determine product distributions and intermediate lifetimes.

Main Results:

• In the gas phase, only 10% of reactive trajectories followed the oxygen rebound pathway.
• In implicit acetone solvent, the oxygen rebound pathway increased to 90% efficiency.
• The oxygen rebound pathway becomes barrierless in acetone solution.
• Short-lived diradical intermediates were observed, with C-H bond breaking to C-O bond formation occurring within 30-150 fs.

Conclusions:

• Solvent effects significantly influence the reaction outcome of DMDO with isobutane.
• Acetone solvent dramatically enhances the efficiency of the oxygen rebound pathway.
• The observed timescales of C-O bond formation are consistent with experimental data for similar radical pair lifetimes.