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Kinetic and mechanistic study of Ru(III) catalysed oxidation of anti-cholinergic drug hyoscinebutylbromide by diperiodatocuprate(III) in aqueous alkaline medium
Author : Govindrajnaj T. Nayak a,b, Vidyadhar C. Havanur a,b and Abdulazizkhan L. Harihar *c
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ABSTRACT
Hyoscine butyl bromide (HBB) is an anti-cholinergic and anti-muscarinic drug used to treat pain and discomfort caused by abdominal cramps etc. It is semi-synthetic derivative alkaloid hyoscyamine having a broad spectrum of activity. Hence the Ru(III) catalyzed the oxidation of hyoscine butyl bromide drug by diperiodatocuprate(III) (DPC) in aqueous alkaline medium was investigated and monitored spectrophotometrically (max = 415 nm) at a constant ionic strength of 0.1 mol dm–3 and 301K. The reaction shows 1:2 stoichiometry between HBB and DPC. The reaction is of the first order in [DPC] and [Ru(III)] and less than unit order in [HBB] and [alkali], periodate has a retarding effect on the reaction rate. The ionic strength, dielectric constant of the medium and added products has no significant effect on the rate of the reaction but Ru(III) increases the reaction rate. The main oxidation products of HBB were identified by spectral studies. The active forms of catalyst and oxidant were detected as Ru(III), [Cu(H2IO6)(H2O)2] respectively. The rate law and reaction mechanism was proposed. The equilibrium constants and rate constants were calculated. The activation parameters were deliberated for catalyzed and uncatalyzed reactions.
KEYWORD
Hyoscine butyl bromide, DPC(III), Ru(III), oxidation, kinetics, mechanism