Alcohol imination catalyzed by carbon nanostructures synthesized by C(sp2)-C(sp3) free radical coupling

Cheng Wang; Zirui Qiao; Yulan Tian; Haijun Yang; Huaqiang Cao; Anthony K Cheetham

doi:10.1016/j.isci.2023.106659

Alcohol imination catalyzed by carbon nanostructures synthesized by C(sp²)-C(sp³) free radical coupling

iScience. 2023 Apr 10;26(5):106659. doi: 10.1016/j.isci.2023.106659. eCollection 2023 May 19.

Authors

Cheng Wang¹, Zirui Qiao¹, Yulan Tian¹, Haijun Yang¹, Huaqiang Cao¹, Anthony K Cheetham²

Affiliations

¹ Department of Chemistry, Tsinghua University, Beijing 100084, China.
² Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.

Abstract

Imines are important intermediates for synthesizing various fine chemicals, with the disadvantage of requiring the use of expensive metal-containing catalysts. We report that the dehydrogenative cross-coupling of phenylmethanol and benzylamine (or aniline) directly forms the corresponding imine with a yield of up to 98%, and water as the sole by-product, in the presence of a stoichiometric base, using carbon nanostructures as the "green" metal-free carbon catalysts with high spin concentrations, which is synthesized by C(sp²)-C(sp³) free radical coupling reactions. The catalytic mechanism is attributed to the unpaired electrons of carbon catalysts to reduce O₂ to O₂^·-, which triggers the oxidative coupling reaction to form imines, whereas the holes in the carbon catalysts receive electrons from the amine to restore the spin states. This is supported by density functional theory calculations. This work will open up an avenue for synthesizing carbon catalysts and offer great potential for industrial applications.

Keywords: Catalysis; Nanostructure; Organic synthesis.