Interaction of procainamide hydrochloride (PAH) with human serum albumin (HSA) is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp–214 was estimated employing the Förster's theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA (Sudlow's site I). The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra (SFS), 3D fluorescence spectra and circular dichroism (CD) results indicated the conformational changes in the structure of HSA.

Oxidation of thiamine hydrochloride (vitamin B 1 ) by cerium(IV) mediated by micro amounts (10 -6 mol dm -3 ) of ruthenium(III) in aqueous perchloric acid medium has been studied spectrophotometrically at 25°C and I = 1.10 mol dm -3 . The reaction is first order in both cerium(IV) and ruthenium(III) concentrations. The order with respect to vitamin B 1 concentration varies from first order to zero order as the vitamin B 1 concentration increases. An increase in perchloric acid concentratrion decreases the reaction rate. The active species of oxidant and catalyst are [Ce(OH) 3? ] and [Ru(H 2 O) 6 ] 3? . A possible mechanism is proposed and reaction constants involved have been determined. The activation parameters for the slow step of the mechanism are determined.

Chloramphenicol is considered a prototypical broad band spectrum antibiotic, alongside the tetracyclines, and finds extensive applications in pharmaceuticals. Hence, its oxidation kinetic study is of much significance in understanding the mechanistic profile in biological systems. In this regard, a systematic study of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in the presence of micro amounts (10 −8 mol/dm 3 ) of Pd(II) and Os(VIII) catalysts has been investigated spectrophotometrically in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm −3 . The reaction between CHP and DPC in alkaline medium exhibits 1:2 stoichiometry in both catalyzed reactions (CHP:DPC). The oxidation products in both reactions were found to be the same and were identified and confirmed by IR, GC-MS, and 1 H NMR. The order with respect to DPC concentration was unity, while the order with respect to CHP concentration varied from first order to zero order as the concentration of CHP increased. The rates increased with increase in [OH − ] and decreased with increase in [IO 4 − ]. The order with respect to [Pd(II)] and [Os(VIII)] was unity. It is observed that the catalytic efficiency for the title reaction is in the order of Pd(II) > Os(VIII). The catalytic constant was also determined at different temperatures for both reactions. The proposed mechanisms and the derived rate laws are in concurrence with the observed kinetics. The activation parameters with respect to the limiting step of the mechanism were calculated, and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(H 2 IO 6 )(H 2 O) 2 ], [Pd(OH) 2 Cl 2 ] 2− , and [OsO 4 (OH) 2 ] 2− are the reactive oxidizing species of Cu(III), Pd(II), and Os(VIII).

The kinetics of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1:2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR and GCMS spectral studies. The reaction is of first order in DPC and CHP concentrations. As the alkali concentration increases the rate of reaction increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined.

The kinetics of ruthenium(III) catalyzed oxidation of chloramphenicol (CHP) by diperiodatocu prate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.1 mol l -1 was studied spectro photometrically. The reaction between DPC and CHP in alkaline medium exhibits 1 : 2 stoichiometry (CHP : DPC). The main oxidation products were identified by spot test, IR, NMR, and GC MS spectral studies. The reaction is first order with respect to ruthenium(III) and DPC concentrations. The order with respect to chloramphenicol concentration varies from first order to zero order as the chloramphenicol con centration increases. As the alkali concentration increases the reaction rate increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A mechanism adequately describing the observed regularities is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to limiting step of the mech anism are computed and discussed. Thermodynamic quantities are determined.