Facilitated proton transfer reactions across liquid|liquid interfaces. Computer simulations and experimental data.

F. VEGA MERCADO, J. M. OVEJERO, R. A. FERNÁNDEZ, S. A. DASSIE

Praga

Conferencia; 48th Heyrovský Discussion: Progress in Elecrochemistry at Liquid-Liquid Interfaces and Liquid Membranes; 2015

This work summarizes different features (experiments and models) of facilitated proton transfer or protonated species transfer reactions across liquid|liquid interfaces [1,2]. The equations used to model the processes allow simulating the systems in all the possible conditions, including the explicit consideration of the water autoprotolysis [3,4]. On this regard, two different approaches are presented: buffered solutions and unbuffered solutions considering the water autoprotolysis [5,6]. The model is corroborated by the experimental results for quinidine transfer across the H2O|1,2-dichloroethane interface, and the corresponding transfer mechanism is analysed in terms of the current-potential and concentration profiles obtained from simulations [5,6]. In the second place, this work also presents the derivation of the general equations for the half-wave potential of facilitated proton transfer or protonated species transfer reactions across liquid|liquid interfaces, including ion pairing. The main equation allows simulating different chemical systems: hydrophilic and hydrophobic neutral bases, multiple protonated species, and ion-pair formation in the organic phase [7].Finally, an experimental analysis of the effect of forced hydrodynamic conditions on the current-potential profiles is discussed. This analysis is focused on facilitated proton transfer via water autoprotolysis [3]. This charge transfer process is an interesting example where the charge transfer reaction occurs with the formation of different products in each phase, i.e. protonated weak base in organic phase and the hydroxide ion in aqueous phase. Furthermore, one of the reactants (water) is always in excess of the other one (neutral weak base). These features provide unique characteristics to facilitated proton transfer via water autoprotolysis to be explored by applying forced hydrodynamic conditions.AcknowledgementsF.V.M and J.M.O. thank CONICET for the fellowships granted. Financial support from CONICET, Secretaría de Ciencia y Tecnología de la Universidad Nacional de Córdoba (SECyT-UNC) and Program BID/OC-AR PICT No 2012-1820 are gratefully acknowledged.References [1]J.I. Garcia, R.A. Fernández, A.J. Ruggeri, S.A. Dassie, J. Electroanal. Chem. 594 (2006) 80.[2]R.A. Iglesias, S.A. Dassie, Ion Transfer at Liquid/Liquid Interfaces, Nova Publishers, New York, 2010.[3]S.A. Dassie, J. Electroanal. Chem. 578 (2005) 159.[4]S.A. Dassie, J. Electroanal. Chem. 585 (2005) 256.[5]J.I. Garcia, R.A. Iglesias, S.A. Dassie, J. Electroanal. Chem. 586 (2006) 225.[6]J.I. Garcia, M.B. Oviedo, S.A. Dassie, J. Electroanal. Chem. 645 (2010) 1.[7]S.A. Dassie, J. Electroanal. Chem. 728 (2014) 51.