Journal Article
Proceedings of the National Academy of Sciences, vol. 109, iss. 39, pp. 15634-15639, 2012
Authors
Douglas H. Pool, Michael P. Stewart, Molly O’Hagan, Wendy J. Shaw, John A. S. Roberts, R. Morris Bullock, Daniel L. DuBois
Abstract
The electrocatalytic reduction of protons to H
2
by
(where
in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water. A turnover frequency of 43,000–53,000 s
-1
has been measured for hydrogen production at 25 °C when the mole fraction of water (
χ
H
2
O
) is 0.72. The same catalyst in acetonitrile with added dimethylformamidium trifluoromethanesulfonate and water has a turnover frequency of 720 s
-1
. Thus, the use of an ionic liquid/aqueous solution enhances the observed catalytic rate by more than a factor of 50, compared to a similar acid in a traditional organic solvent. Complexes
(X = H, OMe,CH
2
P(O)(OEt)
2
, Br) are also catalysts in the ionic liquid/water mixture, and the observed catalytic rates correlate with the hydrophobicity of
X
.
