Nuclear Magnetic Resonance Study of CO Capture by Fluoroalkylamines: Ammonium Ion p Depression via Fluorine Modification and Thermochemistry of Carbamylation.

We are developing energy-efficient and reversible carbon capture and release (CCR) systems that mimic the Lys carbamylation reaction in the active site of ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO). The multiequilibria scenario ammonium ion amine ⇌ carbamic acid ⇌ carbamate requires the presence of both free amine and CO for carbamylation and is affected by the p(). Two fluorination strategies aimed at ammonium ion p depression and low pH carbamylation were analyzed with (2,2,2-trifluoroethyl)butylamine and 2,2-difluoropropylamine and compared to butylamine . The determination of and Δ of the carbamylation reactions requires the solution of multiequilibria systems of equations based on initial conditions, H NMR measurements of carbamylation yields over a wide pH range, and knowledge of - values. and describe carbonic acid acidity, and ammonium ion acidities were measured experimentally. We calibrated carbamic acid acidities based on the measured value of aminocarbamic acid using isodesmic reactions. The proton exchange reactions were evaluated with ab initio computations at the APFD/6-311+G* level in combination with continuum solvation models and explicit solvation. The utilities of - will be discussed as they pertain to the development of fluorine-modified RuBisCO-mimetic reversible CCR systems.