Issue 3, 2020

CO2 activation through C–N, C–O and C–C bond formation

Abstract

A comparative model for the chemisorption of CO2 was explored via three representative reaction pathways: carboxylation of cyclohexanone, carbonation of cyclohexanol, and carbamation of cyclohexylamine. The model substrates were activated using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, an amidine superbase). For each of these reactions, the formation of the corresponding CO2 adducts was confirmed by 13C nuclear magnetic resonance and Fourier-transform infrared spectroscopy measurements. It was demonstrated that CO2 fixation occurred through either an enol-CO2 adduct (i.e. carboxylation), proton shuttling process (i.e. carbonation), or self-activation mechanism (i.e. carbamation). Volumetric adsorption measurements indicated that cyclohexanol was superior in its uptake capacity (11.7 mmol CO2 g−1 sorbent) in comparison to cyclohexylamine (9.3 mmol CO2 g−1 sorbent) or cyclohexanone (8.5 mmol CO2 g−1 sorbent). As supported by density functional theory calculations, this trend was expected given the fact that the carbonation reaction proceeded through a more thermodynamically favorable reaction process.

Graphical abstract: CO2 activation through C–N, C–O and C–C bond formation

Supplementary files

Article information

Article type
Paper
Submitted
02 Nov 2019
Accepted
07 Dec 2019
First published
09 Dec 2019

Phys. Chem. Chem. Phys., 2020,22, 1306-1312

CO2 activation through C–N, C–O and C–C bond formation

A. F. Eftaiha, A. K. Qaroush, I. K. Okashah, F. Alsoubani, J. Futter, C. Troll, B. Rieger and K. I. Assaf, Phys. Chem. Chem. Phys., 2020, 22, 1306 DOI: 10.1039/C9CP05961J

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