TY - JOUR
T1 - Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution I
T2 - Acid and Base Coordinate and Charge Dynamics
AU - Daschakraborty, Snehasis
AU - Kiefer, Philip M.
AU - Miller, Yifat
AU - Motro, Yair
AU - Pines, Dina
AU - Pines, Ehud
AU - Hynes, James T.
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/3/17
Y1 - 2016/3/17
N2 - Protonation by carbonic acid H2CO3 of the strong base methylamine CH3NH2 in a neutral contact pair in aqueous solution is followed via Car-Parrinello molecular dynamics simulations. Proton transfer (PT) occurs to form an aqueous solvent-stabilized contact ion pair within 100 fs, a fast time scale associated with the compression of the acid-base hydrogen-bond (H-bond), a key reaction coordinate. This rapid barrierless PT is consistent with the carbonic acid-protonated base pKa difference that considerably favors the PT, and supports the view of intact carbonic acid as potentially important proton donor in assorted biological and environmental contexts. The charge redistribution within the H-bonded complex during PT supports a Mulliken picture of charge transfer from the nitrogen base to carbonic acid without altering the transferring hydrogen's charge from approximately midway between that of a hydrogen atom and that of a proton.
AB - Protonation by carbonic acid H2CO3 of the strong base methylamine CH3NH2 in a neutral contact pair in aqueous solution is followed via Car-Parrinello molecular dynamics simulations. Proton transfer (PT) occurs to form an aqueous solvent-stabilized contact ion pair within 100 fs, a fast time scale associated with the compression of the acid-base hydrogen-bond (H-bond), a key reaction coordinate. This rapid barrierless PT is consistent with the carbonic acid-protonated base pKa difference that considerably favors the PT, and supports the view of intact carbonic acid as potentially important proton donor in assorted biological and environmental contexts. The charge redistribution within the H-bonded complex during PT supports a Mulliken picture of charge transfer from the nitrogen base to carbonic acid without altering the transferring hydrogen's charge from approximately midway between that of a hydrogen atom and that of a proton.
UR - http://www.scopus.com/inward/record.url?scp=84962566933&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.5b12742
DO - 10.1021/acs.jpcb.5b12742
M3 - Article
C2 - 26879554
AN - SCOPUS:84962566933
SN - 1520-6106
VL - 120
SP - 2271
EP - 2280
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 9
ER -