The oxidative decarboxylation of polyaminocarboxylic acidm-VI Reaction of diethylenetriaminepenta-acetic acid with cerium(IV) in sulphuric acid media.

The oxidation of diethylenetrianunepenta-acetic acid (DTPA) by Ce(IV) in sulphuric add was investigated spectrophotometrically by the stopped-flow technique. The rate of reaction is influenced by the acidity, but can be expressed by a simplified rate law At [H(2)SO(4)] below 0.75M the reaction proceeds stepwise as shown by formation of a 1:1 Ce(IV)-DTPA complex with measurable rate of formation and decay. At higher acid strengths, the formation of an intermediate is not evident. The rate is maximal in ~ 0.75M sulphuric add. The overall stoichiometry varies with time.