Kinetics of aqueous media reactions via ab initio enhanced molecular dynamics: the case of urea decomposition

TL;DR

This study uses enhanced ab initio molecular dynamics to investigate how water molecules influence urea decomposition, revealing the solvent's active role in reaction mechanisms and kinetics.

Contribution

It provides a detailed mechanistic understanding of urea decomposition in aqueous media using advanced simulation techniques, emphasizing solvent effects.

Findings

Water hydrogen-bond network affects reaction dynamics

Reaction free energy calculated with solvent effects

Solvent molecules actively participate in the reaction mechanism

Abstract

Aqueous solutions provide a medium for many important reactions in chemical synthesis, industrial processes, environmental chemistry, and biological functions. It is an accepted fact that aqueous solvents can be direct participants to the reaction process and not act only as simple passive dielectrics. Assisting water molecules and proton wires are thus essential for the efficiency of many reactions. Here we study the decomposition of urea into ammonia and isocyanic acid by means of enhanced ab initio molecular dynamics simulations. We highlight the role of the solvent molecules and their interactions with the reactants providing a proper description of the reaction mechanism and how the water hydrogen-bond network affects the reaction dynamics. Reaction free energy and rates have been calculated taking into account this important effect.