by Michael Padilla
Insights from experiments at Sandia designed to push chemical systems far from equilibrium allowed an international group of researchers to discover a new major source of formic acid over the Pacific and Indian oceans.
The discovery was published in the July 3 issue of Nature Communications and featured on the editor’s highlights webpage. The project was a collaboration among Sandia, the University of New South Wales, the University of Leeds, the University of the Pacific and the University of Minnesota.
In addition to being the smallest organic acid and an important chemical for communication among ants, formic acid plays an important role in atmospheric chemistry, affecting rainwater acidity. However, global atmospheric models significantly underpredict the amount of formic acid present in the troposphere compared to direct measurements.
Inspired by earlier work led by Sandia researcher Craig Taatjes of combustion chemistry, Sandia physical chemist David Osborn and his colleagues hypothesized that vinyl alcohol could be a chemical precursor to the missing formic acid.
However, there was a hitch: vinyl alcohol is a metastable form, or isomer, of the common molecule acetaldehyde. At equilibrium and room temperature, there is only one vinyl alcohol molecule for every 3.3 million acetaldehyde molecules. Something would need to push this mixture far from its natural composition for there to be enough vinyl alcohol molecules to potentially impact formic acid concentrations.
The answer to this puzzle came through David’s explorations of a foundational scientific Grand Challenge from the DOE’s Office of Basic Energy Sciences, which funded the work: to harness systems far from equilibrium. Forcing a chemical system far from equilibrium could allow chemists to explore unusual molecular configurations that may have valuable properties for energy capture and energy storage.