TY - JOUR
T1 - Origin of Free Energy Barriers of Decarboxylation and the Reverse Process of CO2Capture in Dimethylformamide and in Water
AU - Zhou, Shaoyuan
AU - Nguyen, Bach T.
AU - Richard, John P.
AU - Kluger, Ronald
AU - Gao, Jiali
N1 - Publisher Copyright:
©
PY - 2021/1/13
Y1 - 2021/1/13
N2 - In aqueous solution, biological decarboxylation reactions proceed irreversibly to completion, whereas the reverse carboxylation processes are typically powered by the hydrolysis of ATP. The exchange of the carboxylate of ring-substituted arylacetates with isotope-labeled CO2 in polar aprotic solvents reported recently suggests a dramatic change in the partition of reaction pathways. Yet, there is little experimental data pertinent to the kinetic barriers for protonation and thermodynamic data on CO2 capture by the carbanions of decarboxylation reactions. Employing a combined quantum mechanical and molecular mechanical simulation approach, we investigated the decarboxylation reactions of a series of organic carboxylate compounds in aqueous and in dimethylformamide solutions, revealing that the reverse carboxylation barriers in solution are fully induced by solvent effects. A linear Bell-Evans-Polanyi relationship was found between the rates of decarboxylation and the Gibbs energies of reaction, indicating diminishing recombination barriers in DMF. In contrast, protonation of the carbanions by the DMF solvent has large free energy barriers, rendering the competing exchange of isotope-labeled CO2 reversible in DMF. The finding of an intricate interplay of carbanion stability and solute-solvent interaction in decarboxylation and carboxylation could be useful to designing novel materials for CO2 capture.
AB - In aqueous solution, biological decarboxylation reactions proceed irreversibly to completion, whereas the reverse carboxylation processes are typically powered by the hydrolysis of ATP. The exchange of the carboxylate of ring-substituted arylacetates with isotope-labeled CO2 in polar aprotic solvents reported recently suggests a dramatic change in the partition of reaction pathways. Yet, there is little experimental data pertinent to the kinetic barriers for protonation and thermodynamic data on CO2 capture by the carbanions of decarboxylation reactions. Employing a combined quantum mechanical and molecular mechanical simulation approach, we investigated the decarboxylation reactions of a series of organic carboxylate compounds in aqueous and in dimethylformamide solutions, revealing that the reverse carboxylation barriers in solution are fully induced by solvent effects. A linear Bell-Evans-Polanyi relationship was found between the rates of decarboxylation and the Gibbs energies of reaction, indicating diminishing recombination barriers in DMF. In contrast, protonation of the carbanions by the DMF solvent has large free energy barriers, rendering the competing exchange of isotope-labeled CO2 reversible in DMF. The finding of an intricate interplay of carbanion stability and solute-solvent interaction in decarboxylation and carboxylation could be useful to designing novel materials for CO2 capture.
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U2 - 10.1021/jacs.0c12414
DO - 10.1021/jacs.0c12414
M3 - Article
C2 - 33375792
AN - SCOPUS:85099038868
SN - 0002-7863
VL - 143
SP - 137
EP - 141
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 1
ER -