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- Title
Boronic acid-facilitated α-hydroxy-carboxylate anion transfer at liquid/liquid electrode systems: the EIC<sub>rev</sub> mechanism.
- Authors
Najoua Katif; Rachel Harries; Andrew Kelly; John Fossey; Tony James; Frank Marken
- Abstract
Abstract The transfer of the α-hydroxy-carboxylates of glycolic, lactic, mandelic and gluconic acid from the aqueous electrolyte phase into an organic 4-(3-phenylpropyl)-pyridine (PPP) phase is studied at a triple-phase boundary electrode system. The tetraphenylporphyrinato complex MnTPP dissolved in PPP is employed to drive the anion transfer reaction and naphthalene-2-boronic acid (NBA) is employed as a facilitator. In the absence of a facilitator, the ability of α-hydroxy-carboxylates to transfer into the organic phase improves, consistent with hydrophobicity considerations giving relative transfer potentials (for aqueous 0.1 M solution) of gluconate>glycolate>lactate>mandelate. In the presence of NBA, a shift of the reversible transfer potential to more negative values is indicating fast reversible binding (the mechanism for the electrode process is EICrev) and the binding constants are determined as K glycolate = 2 M−1, K mandelate = 60 M−1, K lactate = 130 M−1 and K gluconate = 2,000 M−1. The surprisingly strong interaction for gluconate is rationalised based on secondary interactions between the gluconate anion and NBA.
- Subjects
ELECTROLYTE solutions; ORGANIC acids; ELECTRODES; ION exchange (Chemistry); HYDROPHOBIC surfaces; SURFACE analysis; CHEMICAL reactions; SOLUTION (Chemistry)
- Publication
Journal of Solid State Electrochemistry, 2009, Vol 13, Issue 10, p1475
- ISSN
1432-8488
- Publication type
Article
- DOI
10.1007/s10008-008-0709-x