Zur Kinetik der Reaktion von Aluminium(III) mit Chromotropsäure in wäßrigem Chloressigsäure-Medium

摘要

The kinetics of the reaction of aluminium(III) with chromotropic acid (H4L) by formation of the complex AlL−was studied in the range ofpH=(2.34...3.23) and by variation of the buffer addition to the Al(III) solution. The results leads to a reaction scheme with the species AlOH2+, Al(OH)2+and H2L2−in Al(III) solutions “not prebuffered”, in Al(III) solutions “prebuffered” additionally the species AlClac2−. The difference in the course of the functionskexp=fc0(Al);c(H+) in the Al(III) solutions not prebuffered respective prebuffered was explained: Chromotrophic acid as de facto neutral ligand does not react — contrary to the anionic ligands — with the dimeric Al(III) species present in the Al(III) solutions prebuffered. Water exchange rate constants for the contributing species according to the Eigen-Tamm-model were evaluated and correspond very well with th