Unveiling Solvent Effects on β-Scissions through Metadynamics and Mean Force Integration.

Area of Science:

• Computational Chemistry
• Chemical Kinetics
• Molecular Dynamics

Background:

• Understanding solvent effects is crucial for accurate chemical kinetics.
• Previous gas-phase calculations often fail to match experimental liquid-phase reaction rates.

Purpose of the Study:

• To develop and validate a methodology for investigating solvent effects on chemical reaction kinetics.
• To apply the new method to the β-scission of butyl acrylate (BA) dimer in different solvents.

Main Methods:

• Combining accelerated molecular dynamics and mean force integration.
• Utilizing a hybrid quantum mechanics/molecular mechanics (QM/MM) approach with explicit solvent modeling.

Main Results:

• Solvation in polar (water) and nonpolar (xylene, BA monomer) solvents reduces the activation free energy barrier by ~4 kcal/mol.
• The pre-exponential factor was decreased two-fold in the studied solvents.
• Computed kinetic rate constants closely match experimental measurements, outperforming gas-phase calculations.

Conclusions:

• The developed methodology accurately predicts liquid-phase kinetic rate constants.
• This approach shows significant potential for studying polymerization and depolymerization processes.