Micellar Catalytic Reduction of Glycine by 2,7-Dibromo-4-(Hydroxymercuri)-Fluoresceine Disodium Salt: Kinetic and Thermodynamic Aspects

Abstract

The kinetic reduction of glycine (Gly) by 40.0 μM 2,7-dibromo-4-(hydroxymercuri)-fluoresceine disodium salt [DBHFS] in 0.001 M NaOH at 25°C in aqueous and/or in 30 mM and micellar solutions has been studied using optical absorption at 520 nm. The present data show that the reaction is first-order with respect to [Gly] and [DBHFS]. Also, k obs is constant within the 0.1 mM−0.1 M NaOH range. The reduction was fastest in TX-100, slower in SDS and slowest in CTAB system, that is, rateTX-100 > rateH2O > rateSDS > rateCTAB. Effects of salting-in and salting-out agents have been investigated for real-time application in the reduction process. The salting-in agent urea has been found to uniquely enhance the rate of the reduction of Gly by DBHFS in the presence of micelles. Detailed kinetic and thermodynamic aspects have been considered to realize the interaction between Gly and DBHFS ion. Kinetic studies revealed that the reaction follows pseudo first order reaction kinetics.