Carbonic acid (CA) is formed in any environment which contains water and CO2. It is of fundamental importance for many natural processes studied in chemistry, biology, ecology, geochemistry, and astronomy. CA is known to be an unstable molecule, it experiences fast decomposition into H2O and CO2, a reaction which is catalyzed by water. Despite its fast decomposition, CA should be treated as an important non-vanishing component of the universal H2CO3/HCO–3/CO2 buffer, largely determining the pH of the soils and water reservoirs above and below Earth surface. The stability of intact CA greatly increases with hindered rates of protonation of its conjugate base, the bicarbonate anion. This holds true for many different systems under conditions varying from low temperature environments to aprotic, proton-poor environments. To explore such conditions, we studied the kinetic and thermodynamic properties of CA in methanol-acetonitrile solutions. Stopped-flow mixing experiments to transiently generate CA were performed in wide range of temperatures and methanol-acetonitrile relative compositions. We observe a large increase in the life-time of intact CA at low temperatures and high concentrations of acetonitrile. Currently, we have already found experimental conditions where intact CA lives for about one minute. We verified our observations by FTIR spectroscopy of long-lived CA in methanol-acetonitrile solutions. We plan to extend our measurements and to further increase the life-time of CA in order to depict its decomposition mechanism.

Intact carbonic acid should be considered highly reactive species in the environment

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.