Reversible hydration of α-dicarbonyl compounds from ab initio metadynamics simulations: comparison between pyruvic and glyoxylic acids in aqueous solution

Rodolphe Pollet (1) , Wutharath Chin (2)

1 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)
2 ISMO - Institut des Sciences Moléculaires d'Orsay

Glyoxylic and pyruvic oxoacids are widely available in the atmosphere as gas phase clusters, particles or in wet aerosols. In aqueous conditions, they undergo interconversion between the unhydrated oxo and the gem-diol forms, where two hydroxyl groups replace the carbonyl group. We here examine the hydration equilibrium of glyoxylic and pyruvic acids with first-principle simulations in water at ambient conditions, using ab initio metadynamics to reconstruct the corresponding free-energy landscapes. The main results are as follows: (i) our simulations reveal the high conformational diversity of these species in aqueous solution. (ii) We show that the gem-diol is strongly favored in water compared to its oxo counterpart by 29 kJ/mol and 16 kJ/mol for glyoxylic and pyruvic acids, respectively. (iii) From our atomic scale simulations, we present new insights for the reaction mechanisms with a special focus on hydrogen-bonds arrangements and the electronic structure of the transition state.

Domaines: Chimie théorique et/ou physique

Rodolphe Pollet, Wutharath Chin. Reversible hydration of α-dicarbonyl compounds from ab initio metadynamics simulations: comparison between pyruvic and glyoxylic acids in aqueous solution. Journal of Physical Chemistry B, In press, 125 (11), pp.2942-2951. ⟨10.1021/acs.jpcb.0c09748⟩. ⟨cea-03171716⟩