Friday, November 27, 2015

Chemistry from the Deep: Geomimicry

Hydrothermal vent
Lots of fascinating chemistry occurs in places humans can't routinely visit. Deep-sea hydrothermal vents, super-hot fissures formed from volcanic activity below the ocean floor, produce plumes of minerals and organic compounds. Through "geomimicry," researchers hope to harness similar conditions for use in labs here on dry land.

A team from Arizona State University - a geochemist, a biogeochemist, and a physical chemist  - report in JOC ASAP some interesting oxidation conditions using only copper salts and hot, pressurized water. With cupric chloride as an additive, benzyl alcohol and phenylacetic acid are oxidized to the corresponding benzaldehyde and benzoic acid in water at 250 Celsius and 40 bar (580 psi). The researchers speculate that the copper ions form different chloride species at high T and P, capable of promoting a series of single-electron transfers out of the organic substrates.

The article closes on an intriguing, somewhat humbling note:

"The vast majority of the organic material on Earth does not participate in the familiar, conventional surface carbon cycle because it is located deep within the crust and therefore undergoes chemical reactions under hydrothermal conditions. In contrast to the majority of reactions close to ambient [temperature and pressure], which tend to be controlled by enthalpic and kinetic factors, reactions...under geochemically relevant conditions tend to be controlled by entropic and thermodynamic forces...this suggests that much new useful organic chemistry may be geology."

In other words, the reactions and catalysis we tend to study in labs "above ground" are just the tip of the organic chemistry iceberg....err, volcano?

1 comment:

  1. I am not too impressed, CuBr2 has been used as a mild radical brominating agent for more than a century. It would be more promising if they could use overheated/supercritical water for methane selective oxidative transformation; it is one of the unsolved industry problems, the current steam reforming syngas-based process is really wasteful