
%0 Journal Article
%A Kipton, H 
%A Powell, J 
%A Rate, AW 
%T Aluminum-Tannin Equilibria: A Potentiometric Study
%J Australian Journal of Chemistry
%D 1987/12/01
%V 40
%N 12
%P 2015-2022
%K 
%R https://doi.org/10.1071/CH9872015
%U https://www.publish.csiro.au/paper/CH9872015 
%X The equilibrium reactions between aluminium(III) and an epicatechin polymer or tannin (T) have been studied by potentiometric titration at 25ºC, I = 0.001 M. The tannin, which has on average ten 1,2-dihydroxybenzene units per molecule, encapsulates the aluminium ion to form a bis(l,2-diphenolato) complex at pH 5-7. Stability constants are reported for Al(TH-2) (logK11-2, -3.95 ± 0.05), Al(TH-3) (logK11-3, -4.5 ± 0.1) and Al(TH-4) (logKl1-4, -5.7 ± 0.2). A small chelate effect arising from coordination of remote pairs of 1,2-diphenolato groups was observed. 
