The working conditions and predefined parameters are tabulated in Table , whereas concentrations are expressed from the most volatile component, cyclohexane. Firstly, the operation is managed under the standard atmospheric pressure (760 mm Hg), to distill cyclohexane (95% left in the accumulator). To reach the satisfactory recovery rate of 98.30%, a step must be repeated. Still, the recovery rate is almost 10% higher than what was reported by Bonny for particular configuration and varying reflux policy. The total duration proposed for the best performance of the first step of the process is tf = 3.2 [h]. The optimal control policies for the zeotropic mixture of cyclohexane-(n-heptane)-toluene is depicted in Figure , whereas the optimal costs and recovery rates are tabulated in Table . For the first step, ie. cyclohexane distilling in a small column, as expected the initial and final arc match with the maximum distillate rate (infinite reflux condition -rectifier). After the initial bang arc, the succession of the first range of chattering arcs is perceived, after which only a singular arc exists between 0.025 and 0.13 [h], it is followed by the second succession of the chattering arcs that are to exist until 0.16 [h]. The optimal control trajectory starts as an innocent-looking problem, with chattering arcs for which the controls switch infinitely often on an arbitrary small interval as the switchings accumulate at the final time. These trajectories are defined as chattering arcs with an infinite number of switchings that accumulate with a geometric progression at the final time tf=0 (Schattler and Ledzevicz ).