Nonlinear Oxidation of Thiourea in an Unbuffered Medium

The reaction between periodate and thiourea has been studied in an unbuffered medium. A variety of interesting dynamical behavior including variable stoichiometries, characteristic "clock reaction" and oligooscillations or single peak oscillations in pH, the concentrations of both iodide and iodine were found in a closed reactor. When studied in an open reactor, the above reaction system displays fascinating damped oscillations and bistability in an unbuffered aqueous solution. A 12-step simplified mechanism has also been proposed here. Our investigation illustrates that it is critical to include a rapid H+-mediated preequilibrium step in the suggested mechanism. The modified mechanism gives a better agreement between the calculated results and experimental observations.