Growing concern about global climate change is driving the demand for efficient, cost-effective, and durable processes to separate CO₂ from the flue gas of coal-fired power plants. The most common approach to CO₂ separation is chemical absorption using aqueous ethanolamine. In this reaction, two amine molecules combine with one CO₂ to make a carbamate anion and ammonium cation. In this work, we use first principles simulations to examine the dependence of the thermodynamics of the carbamate reaction on the amine. We calculate gas-phase and solution-phase energetics over the full molecular conformational space, analyze the contributions of carbamate and ammonium formation to overall reaction energies, and discuss the potential to tune reactivity by modification of functional groups. We further consider the implications of these results for the selection of amine functional groups for reactive ionic liquids (or so-called “task specific” ionic liquids) under study as alternatives to the ethanolamine system. Ionic liquids present a unique reaction environment for formation of carbamate, and we consider the consequences of cation vs. anion tethering of amines.