MnII catalyzed oxidation of hexane-1,6-diamine by diperiodatocuprate(III) in aqueous alkaline medium – A kinetic and mechanistic approach

Chemistry Department, B. V. Bhoomaraddi College of Engineering and Technology,

Hubballi-580 031, Karnataka, India

Chemistry Department, KLE Technological University, Hubballi-580 031, Karnataka, India

Chemistry Department, Kittle Science College, Dharwad, Karnataka, India

Government Pre University College, Karajagi, JH-174 Haveri, Karnataka, India

E-mail : hgs.chem@gmail.com Fax : 91-836-2374985

Manuscript received 15 September 2017, accepted 11 October 2017

The kinetics of Mn^II catalyzed oxidation of hexane-1,6-diamine (HDA) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium was monitored spectrophotometrically (^\(\lambda\)max = 415 nm) at constant ionic strength of 0.1 mol dm^–3 and 301 K. The reaction shows 1 : 4 stoichiometry between HDA and DPC. The reaction is of first order in [DPC] and [Mn^II] and less than unit order in [HDA] and [alkali], periodate has retarding effect on reaction rate. The ionic strength and dielectric constant of the medium has no significant effect on the rate of the reaction. The added Cu^II product also has no effect on the rate of reaction. The main product caprolactam was identified by FTIR, GCMS, NMR, DSC and TGA. The active forms oxidant was detected [Cu(H₂ IO₆ )(H₂O)₂ ]. The rate law and reaction mechanism involving three different complexes was proposed. The equilibrium constants and rate constant were calculated. The activation parameters were deliberated for catalyzed and uncatalyzed reactions at different temperatures.