Title:Spectrophotometer Aided Kinetic, Mechanistic and Thermodynamic Study of Ruthenium(III) Catalysed Oxidation of Esmolol by Sulphate of Cerium(IV) in Aqueous Sulphuric Acid Medium
VOLUME: 8 ISSUE: 1
Author(s):Amballa Ram Gopal* and Nowduri Annapurna
Affiliation:Departement of Engineering Chemistry, AUCE (A), Andhra University, Visakhapatnam, 530003, Departement of Engineering Chemistry, AUCE (A), Andhra University, Visakhapatnam, 530003
Keywords:Catalyst, kinetics, oxidation, ruthenium, spectrophotometry, zero order.
Abstract:Aim: The kinetics and mechanism of Ruthenium catalysed oxidation of Esmolol by
Cerium(IV) sulphate in aqueous H2SO4 at a constant ionic strength of 0.50 mol dm-3 was studied
spectrophotometrically.
Observation: The reaction showed first order kinetics in both Cerium(IV) and Ruthenium(III)
whereas fractional order in Esmolol. Addition of products showed no effect on the rate of the
reaction. The main product, methyl-3-(4-(2-hydroxy-3-oxopropoxy) phenyl) propanoate, was
identified with the aid of IR and Mass Spectral data. Stoichiometry with respect to the drug
substrate and reagent was established as 2:1. Added H2SO4, SO4
2- and HSO4- showed negligible
influence on the rate of the reaction in the specified concentration limits. HCe(SO4)3-was found to
be the predominant reactive species under the specified experimental conditions.
Conclusion: The rate constants (k), catalytic constant (kc) and equilibrium constant (K6) for the
proposed mechanism were determined. The kinetic and thermodynamic activation parameters were
computed for both the slow rate determining step and complex forming equilibrium step. The
catalyst exerted its influence by forming a complex with the drug substrate through metal-substrate
bonding in the pre-rate determining step.
