Journal article

Authors list: Schreiner, PR; Reisenauer, HP; Ley, D; Gerbig, D; Wu, CH; Allen, WD

Publication year: 2011

Pages: 1300-1303

Journal: Science

Volume number: 332

Issue number: 6035

DOI Link: https://doi.org/10.1126/science.1203761

Publisher: American Association for the Advancement of Science

Abstract: 

Chemical reactivity is conventionally understood in broad terms of
kinetic versus thermodynamic control, wherein the decisive factor is the
lowest activation barrier among the various reaction paths or the
lowest free energy of the final products, respectively. We demonstrate
that quantum-mechanical tunneling can supersede traditional kinetic
control and direct a reaction exclusively to a product whose reaction
path has a higher barrier. Specifically, we prepared
methylhydroxycarbene (H₃C–C–OH) via vacuum pyrolysis of
pyruvic acid at about 1200 kelvin (K), followed by argon matrix trapping
at 11 K. The previously elusive carbene, characterized by ultraviolet
and infrared spectroscopy as well as exacting quantum-mechanical
computations, undergoes a facile [1,2]hydrogen shift to acetaldehyde via
tunneling under a barrier of 28.0 kilocalories per mole (kcal mol^–1),
with a half-life of around 1 hour. The analogous isomerization to vinyl
alcohol has a substantially lower barrier of 22.6 kcal mol^–1 but is precluded at low temperature by the greater width of the potential energy profile for tunneling.

Harvard Citation style: Schreiner, P., Reisenauer, H., Ley, D., Gerbig, D., Wu, C. and Allen, W. (2011) Methylhydroxycarbene: Tunneling Control of a Chemical Reaction, Science, 332(6035), pp. 1300-1303. https://doi.org/10.1126/science.1203761

APA Citation style: Schreiner, P., Reisenauer, H., Ley, D., Gerbig, D., Wu, C., & Allen, W. (2011). Methylhydroxycarbene: Tunneling Control of a Chemical Reaction. Science. 332(6035), 1300-1303. https://doi.org/10.1126/science.1203761