Study of the carbon dioxide chemical fixation—activation by guanidines

Abstract

Fixation of CO 2 is one of the most important priorities of the scientific community dedicated to reduce global warming. In this work, we propose new methods for the fixation of CO 2 using the guanidine bases tetramethylguanidine (TMG) and 1,3,4,6,7,8-hexahydro-2 H-pyrimido[1,2- a]-pyrimidine (TBD). In order to understand the reactions occurring during the CO 2 fixation and release processes, we employed several experimental methods, including solution and solid-state NMR, FTIR, and coupled TGA–FTIR. Quantum mechanical NMR calculations were also carried out. Based on the results obtained, we concluded that CO 2 fixation with both TMG and TBD guanidines is a kinetically reversible process, and the corresponding fixation products have proved to be useful as transcarboxylating compounds. Afterward, CO 2 thermal releasing from this fixation product with TBD was found to be an interesting process for CO 2 capture and isolation purposes.