A series of silylated amines have been synthesized for use as reversible ionic liquids in the application of post‐combustion carbon capture. We describe a molecular design process aimed at influencing industrially relevant carbon capture properties, such as viscosity, temperature of reversal, and enthalpy of regeneration, while maximizing the overall CO2‐capture capacity. A strong structure–property relationship among the silylamines is demonstrated in which minor structural modifications lead to significant changes in the bulk properties of the reversible ionic liquid formed from reaction with CO2.

Abstract:The introduction and removal of protecting groups is ubiquitous in multi-step synthetic schemes. From a green chemistry standpoint, however, alternative strategies that employ in situ and reversible protection and deprotection sequences would be attractive. The reversible reactions of CO2 with amines could provide a possible vehicle for realizing this strategy. Herein, we present (1) the products of reaction of benzylamines with CO2 in a variety of solvents with and without the presence of basic additives; (2) 498(4-aminomethyl)phenyl) methanol with isopropenyl acetate in acetonitrile containing DBU in the absence and presence of CO2.

The Suzuki coupling reaction of basic nitrogen containing substrates (2-bromo- and 2-chloro-4-aminopyridine, and 2-bromo and 2-chloropyridine) with phenylboronic acid using Pd(TPP)2Cl2/K3PO4 in acetonitrile-water biphasic solvent systems under a CO2 or a N2 atmosphere is discussed. It was observed that 2-halo-4-aminopyridine produced quantitative yields of coupled products under a CO2 atmosphere while the yields for the 2-halopyridines were poor. In contrast, the yields of coupled products for the 2-halopyridines substrates were quantitative under a N2 atmosphere while only poor yields were realized for the 2-halo-4-aminopyridines under the same conditions. Evidence is presented which suggests that the presence of CO2 alters the pH of the aqueous phase of the reaction system and the accompanying efficiency of the coupling process. Using a series of buffers to adjust the pH of the aqueous phase, the pH dependence associated with the efficiency of the coupling process is illustrated.

No abstract

No abstract