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

FRANCO V. MERCADO; JUAN OVEJERO; RICARDO FERNÁNDEZ; SERGIO DASSIE

Praga

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

This work summarizes different features (experiments and models) of facilitatedproton transfer or protonated species transfer reactions across liquid|liquid interfaces[1,2]. The equations used to model the processes allow simulating the systems in allthe possible conditions, including the explicit consideration of the waterautoprotolysis [3,4]. On this regard, two different approaches are presented: bufferedsolutions and unbuffered solutions considering the water autoprotolysis [5,6]. Themodel is corroborated by the experimental results for quinidine transfer across theH2O|1,2-dichloroethane interface, and the corresponding transfer mechanism isanalysed in terms of the current-potential and concentration profiles obtained fromsimulations [5,6].In the second place, this work also presents the derivation of the generalequations for the half-wave potential of facilitated proton transfer or protonatedspecies transfer reactions across liquid|liquid interfaces, including ion pairing. Themain equation allows simulating different chemical systems: hydrophilic andhydrophobic neutral bases, multiple protonated species, and ion-pair formation in theorganic phase [7].Finally, an experimental analysis of the effect of forced hydrodynamic conditionson the current-potential profiles is discussed. This analysis is focused on facilitatedproton transfer via water autoprotolysis [3]. This charge transfer process is aninteresting example where the charge transfer reaction occurs with the formation ofdifferent products in each phase, i.e. protonated weak base in organic phase and thehydroxide ion in aqueous phase. Furthermore, one of the reactants (water) is alwaysin excess of the other one (neutral weak base). These features provide uniquecharacteristics to facilitated proton transfer via water autoprotolysis to be explored byapplying 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) andProgram 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.