TY - GEN
T1 - Can carbonic acid protonate biological bases? Support from base protonation in methanol solvent
AU - Aminov, Daniel
AU - Pines, Dina
AU - Philip, M. Kiefer
AU - Daschakraborty, Snehasis
AU - James, T. Hynes
AU - Pines, Ehud
PY - 2019/7/1
Y1 - 2019/7/1
N2 - In separate contributions, we have focussed on demonstrating that
carbonic acid (CA) - historically considered too unstable to be a viable
protonating agent - is able to protonate several types of pH indicators
while behaving as a regular, moderately strong, carboxylic acid.
Together with the experimental support we found for considering CA as a
regular carboxylic acid are theoretical calculations demonstrating CA's
ability to protonate methylamine within 25 fs when forming with it a
contact reactive complex. Here we briefly discuss a further aspect of
this focus, involving the measurement of the lifetime and pKa of CA in
pure methanol. The lifetime in methanol was found to be about 12-fold
longer than in water, showing that the decomposition reaction of CA is
solvent-dependent. The pKa change upon transferring CA from water to
methanol was found to be 4.7 ± 0.1 pKa units, changing from 3.49
± 0.03 to 8.16 ± 0.05: this change is similar to the pKa
change observed for common stable carboxylic acids when these are
transferred from water to methanol. These results add further support of
our earlier proposal that CA can be an important protonating agent of
biological bases in the blood plasma.
AB - In separate contributions, we have focussed on demonstrating that
carbonic acid (CA) - historically considered too unstable to be a viable
protonating agent - is able to protonate several types of pH indicators
while behaving as a regular, moderately strong, carboxylic acid.
Together with the experimental support we found for considering CA as a
regular carboxylic acid are theoretical calculations demonstrating CA's
ability to protonate methylamine within 25 fs when forming with it a
contact reactive complex. Here we briefly discuss a further aspect of
this focus, involving the measurement of the lifetime and pKa of CA in
pure methanol. The lifetime in methanol was found to be about 12-fold
longer than in water, showing that the decomposition reaction of CA is
solvent-dependent. The pKa change upon transferring CA from water to
methanol was found to be 4.7 ± 0.1 pKa units, changing from 3.49
± 0.03 to 8.16 ± 0.05: this change is similar to the pKa
change observed for common stable carboxylic acids when these are
transferred from water to methanol. These results add further support of
our earlier proposal that CA can be an important protonating agent of
biological bases in the blood plasma.
U2 - 10.1051/epjconf/201920509005
DO - 10.1051/epjconf/201920509005
M3 - Conference contribution
VL - 205
SP - 9005
BT - XXI International Conference on Ultrafast Phenomena EPJ Web of Conferences
ER -