Kinetics and mechanism of the reaction of lysine with permanganate ion at different ionic strengths and temperatures

Document Type : Research Paper




The kinetics of Mn(VII) oxidation of lysine in moderately sulfuric acid solutions was studied
spectrophotometrically in the presence and absence of Mn(II) as catalyst. The reaction was arranged
to be under pseudo first-order condition with respect to Mn(VII). The results showed that the pseudo
first-order rate constant increases with increasing [H2SO4], [(Mn)II], and [lysine]. The dependence of
the reaction rate on temperature (20 to 40 °C) and on ionic strength (0 to 0.12 mol dm-3 NaCl) was
also studied. The obtained results showed that the activation energy and H# decrease but S#
increases by increasing the ionic strength. Finally, an equation was derived to calculate the activation
energy dependence on ionic strength based on a Debye-Huckel type equation and a mechanism was
proposed consistent with the observed results.